Evaluation of retinal nerve fiber layer thickness parameters in myopic population using scanning laser polarimetry (GDxVCC).

PubMed

Dada, Tanuj; Aggarwal, A; Bali, S J; Sharma, A; Shah, B M; Angmo, D; Panda, A

2013-01-01

Myopia presents a significant challenge to the ophthalmologist as myopic discs are often large, tilted, with deep cups and have a thinner neuroretinal rim all of which may mimic glaucomatous optic nerve head changes causing an error in diagnosis. To evaluate the retinal fiber layer (RNFL) thickness in low, moderate and high myopia using scanning laser polarimetry with variable corneal compensation (GDxVCC). One hundred eyes of 100 emmetropes, 30 eyes of low myopes (0 to - 4 D spherical equivalent(SE), 45 eyes with moderate myopia (- 4 to - 8D SE), and 30 eyes with high myopia (- 8 to - 15D SE) were subjected to retinal nerve fiber layer assessment using the scanning laser polarimetry (GDxVCC) in all subjects using the standard protocol. Subjects with IOP > 21 mm Hg, optic nerve head or visual field changes suggestive of glaucoma were excluded from the study. The major outcome parameters were temporal-superior-nasal-inferiortemporal (TSNIT) average, the superior and inferior average and the nerve fibre indicator (NFI). The TSNIT average (p = 0.009), superior (p = 0.001) and inferior average (p = 0.008) were significantly lower; the NFI was higher (P less than 0.001) in moderate myopes as compared to that in emmetropes. In high myopia the RNFL showed supranormal values; the TSNIT average, superior and inferior average was significantly higher(p less than 0.001) as compared to that in emmetropes. The RNFL measurements on scanning laser polarimetry are affected by the myopic refractive error. Moderate myopes show a significant thinning of the RNFL. In high myopia due to peripapillary chorioretinal atrophy and contribution of scleral birefringence, the RNFL values are abnormally high. These findings need to be taken into account while assessing and monitoring glaucoma damage in moderate to high myopes on GDxVCC. © NEPjOPH.

Intraocular Pressure and Retinal Nerve Fibre Layer Thickness Changes After Carotid Artery Stenting.

PubMed

Biberoğlu, Esra; Eraslan, Muhsin; Baltacıoğlu, Feyyaz; Midi, İpek

2017-08-01

The aim of this study was to evaluate intraocular pressure (IOP) and retinal nerve fiber layer (RNFL) changes in patients with carotid artery stenosis (CAS) after carotid artery stenting. This study was conducted as a cross-sectional, non-randomised clinical case series. Fifteen male patients (mean age: 63.6±9.1) with CAS and more than 70% carotid artery narrowing were included. All of the patients were followed in the department of neurology and were operated in the interventional radiology division. Eighteen healthy male subjects (mean age: 63.7±5.3) were included in the control group. All of the healthy subjects had a detailed ophthalmological examination and subjects with any chronic eye disease were excluded from the study. All of the participants had a detailed ophthalmological examination including tonometry using Goldmann applanation tonometry and RNFL analysis using optical coherence tomography (RTVue-100 5.1). There were no ocular ischemic symptoms in any of the participants. The mean IOP value was 15.1±2.1 mmHg in the control group and 16.6±2.4 mmHg before stent implantation, 16.4±2.2 mmHg at 1 week after implantation, 16.6±2.5 mmHg at 1 month after implantation, and 16.7±2.9 mmHg at 3 months after implantation in the CAS group. Mean RNFL thickness was 105±6 µm in the control group; in the CAS group, mean RNFL thickness values were 98±27 µm before stent implantation and 103±11 µm, 101±10 µm, and 101±11 µm at 1 week, 1 month, and 3 months after stenting. There were no significant differences between the CAS group and control group regarding IOP and RNFL thickness values (p>0.05). IOP and RNFL thickness also did not show any statistically significant changes from preoperative measurements in 3 months postoperative follow-up in the CAS group (p>0.05). IOP and RNFL thickness remained unchanged after carotid stent implantation in carotid artery stenosis patients with no signs of ocular ischemic syndrome.

Intraocular Pressure and Retinal Nerve Fibre Layer Thickness Changes After Carotid Artery Stenting

PubMed Central

Biberoğlu, Esra; Eraslan, Muhsin; Baltacıoğlu, Feyyaz; Midi, İpek

2017-01-01

Objectives: The aim of this study was to evaluate intraocular pressure (IOP) and retinal nerve fiber layer (RNFL) changes in patients with carotid artery stenosis (CAS) after carotid artery stenting. Materials and Methods: This study was conducted as a cross-sectional, non-randomised clinical case series. Fifteen male patients (mean age: 63.6±9.1) with CAS and more than 70% carotid artery narrowing were included. All of the patients were followed in the department of neurology and were operated in the interventional radiology division. Eighteen healthy male subjects (mean age: 63.7±5.3) were included in the control group. All of the healthy subjects had a detailed ophthalmological examination and subjects with any chronic eye disease were excluded from the study. All of the participants had a detailed ophthalmological examination including tonometry using Goldmann applanation tonometry and RNFL analysis using optical coherence tomography (RTVue-100 5.1). Results: There were no ocular ischemic symptoms in any of the participants. The mean IOP value was 15.1±2.1 mmHg in the control group and 16.6±2.4 mmHg before stent implantation, 16.4±2.2 mmHg at 1 week after implantation, 16.6±2.5 mmHg at 1 month after implantation, and 16.7±2.9 mmHg at 3 months after implantation in the CAS group. Mean RNFL thickness was 105±6 µm in the control group; in the CAS group, mean RNFL thickness values were 98±27 µm before stent implantation and 103±11 µm, 101±10 µm, and 101±11 µm at 1 week, 1 month, and 3 months after stenting. There were no significant differences between the CAS group and control group regarding IOP and RNFL thickness values (p>0.05). IOP and RNFL thickness also did not show any statistically significant changes from preoperative measurements in 3 months postoperative follow-up in the CAS group (p>0.05). Conclusion: IOP and RNFL thickness remained unchanged after carotid stent implantation in carotid artery stenosis patients with no signs of ocular ischemic syndrome. PMID:28845322

Optical Coherence Tomographic Comparison of Cuban Epidemic and Leber’s Hereditary Optic Neuropathy

PubMed Central

Santiesteban-Freixas, Rosaralis; Pola-Alvarado, Lester; Columbie-Garbey, Yannara; Gonzalez-Quevedo, Alina; Juvier-Riesgo, Tamara; Hernandez-Echevarria, Odelaisys; Hedges, Thomas R.; Mendoza-Santiesteban, Carlos

2015-01-01

Abstract Following the epidemic of optic and peripheral neuropathy, which occurred in Cuba between 1991 and 1993, a number of patients have been re-evaluated, including testing with optical coherence tomography (OCT) and electrophysiology. At the same time, a number of patients with Leber’s hereditary optic neuropathy have also been evaluated. The purpose of this study was to detect residual loss of retinal nerve fibre layer (RNFL) in patients who suffered Cuban epidemic optic neuropathy (CEON), and to compare these findings with those in patients with Leber’s hereditary optic neuropathy (LHON). Optical coherence tomography as well as clinical examinations were performed on 11 patients diagnosed with CEON 15 years following the epidemic and 14 patients with LHON. OCT in CEON patients showed thinning of the RNFL in the temporal sector and normal thickness in other quadrants. However, patients with chronic LHON had more diffuse RNFL loss throughout the retina. OCT findings corresponded with clinical findings in CEON and LHON. There was drop out of the papillomacular bundle in both diseases. Two patients in the acute stages of LHON and three LHON carriers showed thinning of the temporal RNFL only. This is the first report of OCT in CEON that shows residual damage in the papillomacular bundle compared with chronic LHON where there is more diffuse and progressive loss of the RNFL. The importance of OCT for the diagnosis and evaluation of similar optic neuropathies is emphasised. PMID:27928368

Retinal nerve fibre thickness measured with optical coherence tomography accurately detects confirmed glaucomatous damage.

PubMed

Hood, D C; Harizman, N; Kanadani, F N; Grippo, T M; Baharestani, S; Greenstein, V C; Liebmann, J M; Ritch, R

2007-07-01

To assess the accuracy of optical coherence tomography (OCT) in detecting damage to a hemifield, patients with hemifield defects confirmed on both static automated perimetry (SAP) and multifocal visual evoked potentials (mfVEP) were studied. Eyes of 40 patients with concomitant SAP and mfVEP glaucomatous loss and 25 controls underwent OCT retinal nerve fibre layer (RNFL), mfVEP and 24-2 SAP tests. For the mfVEP and 24-2 SAP, a hemifield was defined as abnormal based upon cluster criteria. On OCT, a hemifield was considered abnormal if one of the five clock hour sectors (3 and 9 o'clock excluded) was at <1% (red) or two were at <5% (yellow). Seventy seven (43%) of the hemifields were abnormal on both mfVEP and SAP tests. The OCT was abnormal for 73 (95%) of these. Only 1 (1%) of the 100 hemifields of the controls was abnormal on OCT. Sensitivity/specificity (one eye per person) was 95/98%. The OCT RNFL test accurately detects abnormal hemifields confirmed on both subjective and objective functional tests. Identifying abnormal hemifields with a criterion of 1 red (1%) or 2 yellow (5%) clock hours may prove useful in clinical practice.

Effect of pupillary dilatation on glaucoma assessments using optical coherence tomography

PubMed Central

Smith, Michael; Frost, Andrew; Graham, Christopher Mark; Shaw, Steven

2007-01-01

Aims To examine the effect of pupillary dilatation on the reliability of retinal nerve fibre layer (RNFL) and optic nerve head (ONH) assessments using Stratus OCT in a glaucoma clinic. Methods Observational study of 38 patients attending a glaucoma clinic. The “fast optic disc” and “fast RNFL thickness” programs on Stratus OCT were used to measure the RNFL thickness and ONH cup to disc ratio (CDR). Two scans were done before dilatation and two after dilatation with tropicamide 1% drops. The mean values and reproducibility before and after dilatation were compared, along with the quality of scans as indicated by the “signal strength” score. Results In nine patients (23.7%) no images were obtained undilated but after dilatation examination was possible in all patients. Inability to obtain an undilated scan was associated with smaller pupil size and increasing cataract. The scan quality, as judged by the signal strength score, was higher dilated than undilated for both RNFL thickness (p = 0.011) and ONH CDR (p = 0.007). Reproducibility was higher with dilated scans for RNFL thickness but not for ONH CDR. There were significant differences between the dilated and undilated examinations for three of the five RNFL thickness variables and two of the three ONH CDR categories. Conclusions Acquisition of high quality OCT images was not possible without pupillary dilatation in about 25% of the patients. The dilated scans were more reproducible and of higher quality than the undilated scans. The two methods of examination do not appear to be interchangeable, suggesting that in follow up examinations the pupil should be in the same condition as at baseline. Pupillary dilatation is recommended before glaucoma assessments using Stratus OCT. PMID:17556429

Peripapillary retinal nerve fiber layer thickness in a population of 6-year-old children: findings by optical coherence tomography.

PubMed

Huynh, Son C; Wang, Xiu Ying; Rochtchina, Elena; Mitchell, Paul

2006-09-01

To study the distribution of retinal nerve fiber layer (RNFL) thickness by ocular and demographic variables in a population-based study of young children. Population-based cross-sectional study. One thousand seven hundred sixty-five of 2238 (78.9%) eligible 6-year-old children participated in the Sydney Childhood Eye Study between 2003 and 2004. Mean age was 6.7 years (50.9% boys). Detailed examination included cycloplegic autorefraction and measurement of axial length. Retinal nerve fiber layer scans using an optical coherence tomographer were performed with a circular scan pattern of 3.4-mm diameter. Multivariate analyses were performed to examine the distribution of RNFL parameters with gender, ethnicity, axial length, and refraction. Peripapillary RNFL thickness and RNFL(estimated integral) (RNFL(EI)), which measures the total cross-sectional area of ganglion cell axons converging onto the optic nerve head. Peripapillary RNFL thickness and RNFL(EI) were normally distributed. The mean+/-standard deviation RNFL average thickness was 103.7+/-11.4 microm and RNFL(EI) was 1.05+/-0.12 mm2. Retinal nerve fiber layer thickness was least for the temporal quadrant (75.7+/-14.7 microm), followed by the nasal (81.7+/-19.6 microm), inferior (127.8+/-20.5 microm), and superior (129.5+/-20.6 microm) quadrants. Multivariate adjusted RNFL average thickness was marginally greater in boys than in girls (104.7 microm vs. 103.2 microm; P = 0.007) and in East Asian than in white children (107.7 microm vs. 102.7 microm; P<0.0001). The RNFL was thinner with greater axial length (P(trend)<0.0001) and less positive spherical equivalent refractions (P(trend) = 0.004). Retinal nerve fiber layer average thickness and RNFL(EI) followed a normal distribution. Retinal nerve fiber layer thickness varied marginally with gender, but differences were more marked between white and East Asian children. Retinal nerve fiber layer thinning was associated with increasing axial length and less positive refractions.

Effect of optic neuritis on progressive axonal damage in multiple sclerosis patients.

PubMed

Garcia-Martin, E; Pueyo, V; Ara, J R; Almarcegui, C; Martin, J; Pablo, L; Dolz, I; Sancho, E; Fernandez, F J

2011-07-01

The objective of this research was to study the effect of optic neuritis (ON) on axonal damage in multiple sclerosis (MS) patients. Specifically, we compared changes over 2 years in the retinal nerve fibre layer (RNFL) between affected and contralateral eyes in MS patients with a prior history of ON. Thirty-four patients with one unilateral definitive episode of ON were included and underwent a complete ophthalmic examination, optical coherence tomography (OCT), scanning laser polarimetry, visual evoked potentials (VEP) and pattern electroretinogram (pERG). All patients were re-evaluated at 12 and 24 months. Parameters were compared between ON-affected and contralateral eyes in an initial exploration and over the course of the follow-up. Correlations between parameter changes were analysed. RNFL thickness and functional parameters showed more affection in ON eyes (p ≤ 0.05), but changes in measurements during the study were similar between both groups of eyes. Progressive axonal loss can be detected in the optic nerve, but ON is not a risk factor for increased chronic damage in MS patients without ophthalmic relapses. Loss of the RNFL is caused by progressive degeneration associated with the disease.

Diagnostic Accuracy of Spectralis SD OCT Automated Macular Layers Segmentation to Discriminate Normal from Early Glaucomatous Eyes.

PubMed

Pazos, Marta; Dyrda, Agnieszka Anna; Biarnés, Marc; Gómez, Alicia; Martín, Carlos; Mora, Clara; Fatti, Gianluca; Antón, Alfonso

2017-08-01

To evaluate the accuracy of the macular retinal layer segmentation software of the Spectralis spectral-domain (SD) optical coherence tomography (OCT) device (Heidelberg Engineering, Inc., Heidelberg, Germany) to discriminate between healthy and early glaucoma (EG) eyes. Prospective, cross-sectional study. Forty EG eyes and 40 healthy controls were included. All participants were examined using the standard posterior pole and the peripapillary retinal nerve fiber layer (pRNFL) protocols of the Spectralis OCT device. Using an Early Treatment Diagnostic Retinopathy Study circle at the macular level, the automated retinal segmentation software was applied to determine thicknesses of the following parameters: total retinal thickness, inner retinal layer (IRL), macular retinal nerve fiber layer (mRNFL), macular ganglion cell layer (mGCL), macular inner plexiform layer (mIPL), macular inner nuclear layer (mINL), macular outer plexiform layer (mOPL), macular outer nuclear layer (mONL), photoreceptors (PR), and retinal pigmentary epithelium (RPE). The ganglion cell complex (GCC) was determined by adding the mRNFL, mGCL, and mIPL parameters and the ganglion cell layer-inner plexiform layer (mGCL-IPL) was determined by combining the mGCL and mIPL parameters. Thickness of each layer was compared between the groups, and the layer and sector with the best area under the receiver operating characteristic curve (AUC) were identified. Comparison of pRNFL, IRL, mRNFL, mGCL, mIPL, mGCC, mGCL-IPL, mINL, mOPL, mONL, PR, and RPE parameters and total retinal thicknesses between groups for the different areas and their corresponding AUCs. Peripapillary RNFL was significantly thinner in the EG group globally and in all 6 sectors assessed (P < 0.0005). For the macular variables, retinal thickness was significantly reduced in the EG group for total retinal thickness, mIRL, mRNFL, mGCL, and mIPL. The 2 best isolated parameters to discriminate between the 2 groups were pRNFL (AUC, 0.956) and mRNFL (AUC, 0.906). When mRNFL, mGCL, and mIPL measurements were combined (mGCC and mGCL plus mIPL), then its diagnostic performance improved (AUC, 0.940 and 0.952, respectively). Macular RNFL, mGCL-IPL, and mGCC measurements showed a high diagnostic capability to discriminate between healthy and EG participants. However, macular intraretinal measurements still have not overcome standard pRNFL parameters. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Retinal nerve fibre thickness measured with optical coherence tomography accurately detects confirmed glaucomatous damage

PubMed Central

Hood, D C; Harizman, N; Kanadani, F N; Grippo, T M; Baharestani, S; Greenstein, V C; Liebmann, J M; Ritch, R

2007-01-01

Aim To assess the accuracy of optical coherence tomography (OCT) in detecting damage to a hemifield, patients with hemifield defects confirmed on both static automated perimetry (SAP) and multifocal visual evoked potentials (mfVEP) were studied. Methods Eyes of 40 patients with concomitant SAP and mfVEP glaucomatous loss and 25 controls underwent OCT retinal nerve fibre layer (RNFL), mfVEP and 24‐2 SAP tests. For the mfVEP and 24‐2 SAP, a hemifield was defined as abnormal based upon cluster criteria. On OCT, a hemifield was considered abnormal if one of the five clock hour sectors (3 and 9 o'clock excluded) was at <1% (red) or two were at <5% (yellow). Results Seventy seven (43%) of the hemifields were abnormal on both mfVEP and SAP tests. The OCT was abnormal for 73 (95%) of these. Only 1 (1%) of the 100 hemifields of the controls was abnormal on OCT. Sensitivity/specificity (one eye per person) was 95/98%. Conclusions The OCT RNFL test accurately detects abnormal hemifields confirmed on both subjective and objective functional tests. Identifying abnormal hemifields with a criterion of 1 red (1%) or 2 yellow (5%) clock hours may prove useful in clinical practice. PMID:17301118

New Normative Database of Inner Macular Layer Thickness Measured by Spectralis OCT Used as Reference Standard for Glaucoma Detection.

PubMed

Nieves-Moreno, María; Martínez-de-la-Casa, José M; Bambo, María P; Morales-Fernández, Laura; Van Keer, Karel; Vandewalle, Evelien; Stalmans, Ingeborg; García-Feijoó, Julián

2018-02-01

This study examines the capacity to detect glaucoma of inner macular layer thickness measured by spectral-domain optical coherence tomography (SD-OCT) using a new normative database as the reference standard. Participants ( N = 148) were recruited from Leuven (Belgium) and Zaragoza (Spain): 74 patients with early/moderate glaucoma and 74 age-matched healthy controls. One eye was randomly selected for a macular scan using the Spectralis SD-OCT. The variables measured with the instrument's segmentation software were: macular nerve fiber layer (mRNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) volume and thickness along with circumpapillary RNFL thickness (cpRNFL). The new normative database of macular variables was used to define the cutoff of normality as the fifth percentile by age group. Sensitivity, specificity, and area under the receiver operating characteristic curve (AUROC) of each macular measurement and of cpRNFL were used to distinguish between patients and controls. Overall sensitivity and specificity to detect early-moderate glaucoma were 42.2% and 88.9% for mRNFL, 42.4% and 95.6% for GCL, 42.2% and 94.5% for IPL, and 53% and 94.6% for RNFL, respectively. The best macular variable to discriminate between the two groups of subjects was outer temporal GCL thickness as indicated by an AUROC of 0.903. This variable performed similarly to mean cpRNFL thickness (AUROC = 0.845; P = 0.29). Using our normative database as reference, the diagnostic power of inner macular layer thickness proved comparable to that of peripapillary RNFL thickness. Spectralis SD-OCT, cpRNFL thickness, and individual macular inner layer thicknesses show comparable diagnostic capacity for glaucoma and RNFL, GCL, and IPL thickness may be useful as an alternative diagnostic test when the measure of cpRNFL shows artifacts.

Diagnostic ability of peripapillary vessel density measurements of optical coherence tomography angiography in primary open-angle and angle-closure glaucoma.

PubMed

Rao, Harsha L; Kadambi, Sujatha V; Weinreb, Robert N; Puttaiah, Narendra K; Pradhan, Zia S; Rao, Dhanaraj A S; Kumar, Rajesh S; Webers, Carroll A B; Shetty, Rohit

2017-08-01

To evaluate the diagnostic ability of peripapillary vessel density measurements on optical coherence tomography angiography (OCTA) in primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG), and to compare these with peripapillary retinal nerve fibre layer (RNFL) thickness measurements. In a cross-sectional study, 48 eyes of 33 healthy control subjects, 63 eyes of 39 patients with POAG and 49 eyes of 32 patients with PACG underwent OCTA (RTVue-XR, Optovue, Fremont, California, USA) and RNFL imaging with spectral domain OCT. Diagnostic abilities of vessel density and RNFL parameters were evaluated using area under receiver operating characteristic curves (AUC) and sensitivities at fixed specificities. AUCs of peripapillary vessel density ranged between 0.48 for the temporal sector and 0.88 for the inferotemporal sector in POAG. The same in PACG ranged between 0.57 and 0.86. Sensitivities at 95% specificity ranged from 13% to 70% in POAG, and from 10% to 67% in PACG. AUCs of peripapillary RNFL thickness ranged between 0.51 for the temporal sector and 0.91 for the inferonasal sector in POAG. The same in PACG ranged between 0.61 and 0.87. Sensitivities at 95% specificity ranged from 8% to 68% in POAG, and from 2% to 67% in PACG. AUCs of all peripapillary vessel density measurements were comparable (p>0.05) to the corresponding RNFL thickness measurements in both POAG and PACG. Diagnostic ability of peripapillary vessel density parameters of OCTA, especially the inferotemporal sector measurement, was good in POAG and PACG. Diagnostic abilities of vessel density measurements were comparable to RNFL measurements in both POAG and PACG. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Association of ocular, cardiovascular, morphometric and lifestyle parameters with retinal nerve fibre layer thickness.

PubMed

Lamparter, Julia; Schmidtmann, Irene; Schuster, Alexander K; Siouli, Angeliki; Wasielica-Poslednik, Joanna; Mirshahi, Alireza; Höhn, René; Unterrainer, Josef; Wild, Philipp S; Binder, Harald; Lackner, Karl; Beutel, Manfred E; Münzel, Thomas; Pfeiffer, Norbert; Hoffmann, Esther M

2018-01-01

Glaucoma is a neurodegenerative disease, leading to thinning of the retinal nerve fibre layer (RNFL). The exact influence of ocular, cardiovascular, morphometric, lifestyle and cognitive factors on RNFL thickness (RNFLT) is unknown and was analysed in a subgroup of the Gutenberg Health Study (GHS). Global peripapillary RNFLT was measured in 3224 eyes of 1973 subjects (49% female) using spectral-domain optical coherence tomography (SD-OCT). The association of age, sex, ocular, cardiovascular, morphometric, lifestyle and cognitive factors on RNFLT was analysed using Pearson correlation coefficient and fitting a linear mixed model. In the univariable analysis highest correlations were found for axial length (r = -0.27), spherical equivalent (r = 0.24), and glaucoma (r = -0.15) (p<0.0001, respectively). Other significant correlations with RNFLT were found for age, sex, intraocular pressure, systemic hypertension and systolic blood pressure, previous eye surgery, cholesterol, homocysteine, history of coronary artery disease, history of myocardial infarction, apnoea, diabetes and alcohol intake, p<0.05, respectively. Body length, body weight, BMI, diastolic blood pressure, blood glucose, HbA1c, history of apoplexy, cognitive function, peripheral artery disease, tinnitus, migraine, nicotine intake, central corneal thickness, and pseudophakia were not significantly correlated with RNFLT. The regression model revealed a significant relationship between RNFLT and age in decades (p<0.02), spherical equivalent (p<0.0001), axial length (p<0.0001), glaucoma (p<0.0001), tinnitus (p = 0.04), apnoea (p = 0.047), homocysteine (p = 0.05) and alcohol intake >10g/d for women and >20g/d for men (p = 0.02). Glaucoma, apnoea, higher homocysteine, higher alcohol intake and higher axial length as well as age were related to decreased RNFLT while higher spherical equivalent or history for tinnitus were related to thicker RNFL. RNFLT is related to age, ocular parameters and lifestyle factors. Considering these parameters in normative databases could improve the evaluation of peripapillary RNFLT. It is necessary to evaluate if a reduction of alcohol intake as well as the therapy of apnea or high homocysteine levels could positively influence RNFLT.

A basis for customising perimetric locations within the macula in glaucoma.

PubMed

Alluwimi, Muhammed S; Swanson, William H; Malinovsky, Victor E; King, Brett J

2018-03-01

It has been recognised that the 24-2 grid used for perimetry may poorly sample the macula, which has been recently identified as a critical region for diagnosing and managing patients with glaucoma. We compared data derived from patients and controls to investigate the efficacy of a basis for customising perimetric locations within the macula, guided by en face images of retinal nerve fibre layer (RNFL) bundles. We used SD-OCT en face montages (www.heidelbergengineering.com) of the RNFL in 10 patients with glaucoma (ages 56-80 years, median 67.5 years) and 30 age-similar controls (ages 47-77, median 58). These patients were selected because of either the absence of perimetric defect while glaucomatous damage to the RNFL bundles was observed, or because of perimetric defect that did not reflect the extent and locations of the glaucomatous damage that appeared in the RNFL images. We used a customised blob stimulus for perimetric testing (a Gaussian blob with 0.25° standard deviation) at 10-2 grid locations, to assess the correspondence between perimetric defects and damaged RNFL bundles observed on en face images and perimetric defects. Data from the age-similar controls were used to compute total deviation (TD) and pattern deviation (PD) values at each location; a perimetric defect for a location was defined as a TD or PD value of -0.5 log unit or deeper. A McNemar's test was used to compare the proportions of locations with perimetric defects that fell outside the damaged RNFL bundles, with and without accounting for displacement of ganglion cell bodies. All patients but one had perimetric defects that were consistent with the patterns of damaged RNFL bundles observed on the en face images. We found six abnormal perimetric locations of 2040 tested in controls and 132 abnormal perimetric locations of 680 tested in patients. The proportions of abnormal locations that fell outside the damaged RNFL bundles, with and without accounting for displacement of the ganglion cell bodies were 0.08 and 0.07, respectively. The difference between the two proportions did not reach statistical significance (p = 0.5 for a one-tailed test). We demonstrated that it is effective to customise perimetric locations within the macula, guided by en face images of the RNFL bundles. The perimetric losses found with a 10-2 grid demonstrated similar patterns as the damaged RNFL bundles observed on the en face images. © 2018 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.

Retinal single-layer analysis with optical coherence tomography shows inner retinal layer thinning in Huntington's disease as a potential biomarker.

PubMed

Gulmez Sevim, Duygu; Unlu, Metin; Gultekin, Murat; Karaca, Cagatay

2018-02-12

There have been ongoing clinical trials of therapeutic agents in Huntington's disease (HD) which requires development of reliable biomarkers of disease progression. There have been studies in the literature with conflicting results on the involvement of retina in HD, and up to date there is not a study evaluating the single retinal layers in HD. We aimed to evaluate the specific retinal changes in HD and their usability as potential disease progression markers. This cross-sectional study used spectral-domain optical coherence tomography with automatic segmentation to measure peripapillary retinal nerve fiber layer (pRNFL) thickness and the thickness and volume of retinal layers in foveal scans of 15 patients with HD and 15 age- and sex-matched controls. Genetic testing results, disease duration, HD disease burden scores and Unified HD Rating Scales motor scores were acquired for the patients. Temporal pRNFL, macular RNFL (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer and outer plexiform layer thicknesses and IPL, retinal pigment epithelium and outer macular volume were found lower in HD compared to controls, while outer nuclear layer and outer retinal layer thickness were increased (p < 0.05). We found significant correlations between inner retinal layer thicknesses, most significantly with mRNFL and GCL and disease progression markers. The outcomes of this study points out that retinal layers, most significantly mRNFL and GCL, are strongly correlated with the disease progression in HD and could serve as useful biomarkers for disease progression.

Validity of the temporal-to-nasal macular ganglion cell-inner plexiform layer thickness ratio as a diagnostic parameter in early glaucoma.

PubMed

Park, Jung-Won; Jung, Hyun-Ho; Heo, Hwan; Park, Sang-Woo

2015-08-01

To evaluate the diagnostic validity of temporal-to-nasal macular ganglion cell-inner plexiform layer thickness (TNM) ratio using Cirrus high definition-optical coherence tomography (HD-OCT) in patients with early glaucomatous damage. Enrolled participants included 130 normal controls, 50 patients with preperimetric glaucoma and 106 patients with early glaucoma. The patients with early glaucoma were classified into two subgroups according to the pattern of the visual field (VF) defects: the paracentral scotoma (PCS, n = 54) and the peripheral scotoma (PPS, n = 52). The thickness of the macular ganglion cell-inner plexiform layer (mGCIPL) and circumpapillary retinal nerve fibre layer (cpRNFL) was measured by Cirrus HD-OCT, and the average, superior and inferior TNM ratio was calculated. The average TNM ratio is a sum of superotemporal and inferotemporal mGCIPL thicknesses divided by the sum of superonasal and inferonasal mGCIPL thicknesses. Area under the receiver operating characteristic curve (AROC) of each parameter was compared between the groups. The parameter with the best AROC was the average TNM ratio and inferotemporal mGCIPL thickness in the PCS group and average cpRNFL thickness in the PPS group. The AROCs of the average, superior and inferior TNM ratio (p < 0.001, p = 0.007 and p < 0.001, respectively), minimum, average, inferotemporal and inferior mGCIPL thickness (p = 0.004, p = 0.003, p = 0.002 and p = 0.001, respectively) of the PCS were significantly higher than those of the PPS. However, the AROCs of the all cpRNFL thickness parameters did not show statistically significant differences between two subgroups. Asymmetry of temporal-to-nasal mGCIPL thickness could be an important parameter in the diagnosis of early glaucoma with paracentral VF defects. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Evaluation of Interocular Retinal Nerve Fiber Layer Thickness Symmetry as a Diagnostic Modality for Glaucoma.

PubMed

Hong, Seung Woo; Lee, Seung Bum; Jee, Dong-Hyun; Ahn, Myung Douk

2016-09-01

The purpose of study was to measure the diagnostic utility of interocular retinal nerve fiber layer (RNFL) symmetry and interocular RNFL thickness comparison. Both eyes of 103 normal subjects and 106 glaucoma patients (31 patients with early glaucoma and 75 patients with moderate to severe glaucoma) received comprehensive ophthalmologic evaluation including visual field testing and optic disc scanning using optical coherence tomography. RNFL thickness values for 256 measurement points were rearranged according to a new reference line connecting the optic disc center and the foveola. The interocular RNFL thickness symmetry value and absolute and fractional interocular difference in RNFL thickness were calculated and compared between groups. Area under the receiver operating characteristic curves (AUROCs) were calculated and compared. Among the parameters reflecting whole RNFL status, the corrected interocular RNFL thickness symmetry exhibited the largest AUROCs at all glaucoma stages. RNFL thickness and absolute and fractional interocular difference in RNFL thickness exhibited largest AUROC in the inferotemporal area, regardless of glaucoma stage. In the early glaucoma group, absolute and fractional interocular RNFL thickness differences in the temporal and superotemporal areas exhibited equal to or larger AUROCs than RNFL thickness. The AUROCs for RNFL thickness were greater than those for absolute and fractional interocular RNFL thickness differences in the moderate to severe glaucoma group except in the nasal and temporal area. The corrected interocular RNFL thickness symmetry value is an effective diagnostic tool for glaucoma. Interocular comparison of RNFL thickness has good diagnostic performance and gives information about the RNFL beyond just the RNFL thickness itself.

Prevalence of Split Nerve Fiber Layer Bundles in Healthy People Imaged with Spectral Domain Optical Coherence Tomography.

PubMed

Gür Güngör, Sirel; Akman, Ahmet; Sarıgül Sezenöz, Almila; Tanrıaşıkı, Gülşah

2016-12-01

The presence of retinal nerve fiber layer (RNFL) split bundles was recently described in normal eyes scanned using scanning laser polarimetry and by histologic studies. Split bundles may resemble RNFL loss in healthy eyes. The aim of our study was to determine the prevalence of nerve fiber layer split bundles in healthy people. We imaged 718 eyes of 359 healthy persons with the spectral domain optical coherence tomography in this cross-sectional study. All eyes had intraocular pressure of 21 mmHg or less, normal appearance of the optic nerve head, and normal visual fields (Humphrey Field Analyzer 24-2 full threshold program). In our study, a bundle was defined as 'split' when there is localized defect not resembling a wedge defect in the RNFL deviation map with a symmetrically divided RNFL appearance on the RNFL thickness map. The classification was performed by two independent observers who used an identical set of reference examples to standardize the classification. Inter-observer consensus was reached in all cases. Bilateral superior split bundles were seen in 19 cases (5.29%) and unilateral superior split was observed in 15 cases (4.16%). In 325 cases (90.52%) there was no split bundle. Split nerve fiber layer bundles, in contrast to single nerve fiber layer bundles, are not common findings in healthy eyes. In eyes with normal optic disc appearance, especially when a superior RNFL defect is observed in RNFL deviation map, the RNLF thickness map and graphs should also be examined for split nerve fiber layer bundles.

Mesenchymal stromal cell-mediated neuroprotection and functional preservation of retinal ganglion cells in a rodent model of glaucoma.

PubMed

Mead, Ben; Hill, Lisa J; Blanch, Richard J; Ward, Kelly; Logan, Ann; Berry, Martin; Leadbeater, Wendy; Scheven, Ben A

2016-04-01

Glaucoma is a leading cause of irreversible blindness involving loss of retinal ganglion cells (RGC). Mesenchymal stromal cells (MSC) have shown promise as a paracrine-mediated therapy for compromised neurons. It is, however, unknown whether dental pulp stem cells (DPSC) are effective as a cellular therapy in glaucoma and how their hypothesized influence compares with other more widely researched MSC sources. The present study aimed to compare the efficacy of adipose-derived stem cells, bone marrow-derived MSC (BMSC) and DPSC in preventing the loss of RGC and visual function when transplanted into the vitreous of glaucomatous rodent eyes. Thirty-five days after raised intraocular pressure (IOP) and intravitreal stem cell transplantation, Brn3a(+) RGC numbers, retinal nerve fibre layer thickness (RNFL) and RGC function were evaluated by immunohistochemistry, optical coherence tomography and electroretinography, respectively. Control glaucomatous eyes that were sham-treated with heat-killed DPSC had a significant loss of RGC numbers, RNFL thickness and function compared with intact eyes. BMSC and, to a greater extent, DPSC provided significant protection from RGC loss and RNFL thinning and preserved RGC function. The study supports the use of DPSC as a neuroprotective cellular therapy in retinal degenerative disease such as glaucoma. Copyright © 2016 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Diagnostic Ability of Wide-field Retinal Nerve Fiber Layer Maps Using Swept-Source Optical Coherence Tomography for Detection of Preperimetric and Early Perimetric Glaucoma.

PubMed

Lee, Won June; Na, Kyeong Ik; Kim, Young Kook; Jeoung, Jin Wook; Park, Ki Ho

2017-06-01

To evaluate the diagnostic ability of wide-field retinal nerve fiber layer (RNFL) maps with swept-source optical coherence tomography (SS-OCT) for detection of preperimetric (PPG) and early perimetric glaucoma (EG). One hundred eighty-four eyes, including 67 healthy eyes, 43 eyes with PPG, and 74 eyes with EG, were analyzed. Patients underwent a comprehensive ocular examination including red-free RNFL photography, visual field testing and wide-field SS-OCT scanning (DRI-OCT-1 Atlantis; Topcon, Tokyo, Japan). SS-OCT provides a wide-field RNFL thickness map and a SuperPixel map, which are composed of the RNFL deviation map of the peripapillary area and the deviation map of the composition of the ganglion cell layer with the inner plexiform layer and RNFL (GC-IPL+RNFL) in the macular area. The ability to discriminate PPG and EG from healthy eyes was assessed using sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) for all parameters and criteria provided by the wide-field SS-OCT scan. The wide-field RNFL thickness map using SS-OCT showed the highest sensitivity of PPG-diagnostic and EG-diagnostic performance compared with the other SS-OCT criteria based on the internal normative base (93.0 and 97.3%, respectively). Among the SS-OCT continuous parameters, the RFNL thickness of the 7 clock-hour, inferior and inferotemporal macular ganglion cell analyses showed the largest AUC of PPG-diagnostic and EG-diagnostic performance (AUC=0.809 to 0.865). The wide-field RNFL thickness map using SS-OCT performed well in distinguishing eyes with PPG and EG from healthy eyes. In the clinical setting, wide-field RNFL maps of SS-OCT can be useful tools for detection of early-stage glaucoma.

Automated Segmentation Errors When Using Optical Coherence Tomography to Measure Retinal Nerve Fiber Layer Thickness in Glaucoma.

PubMed

Mansberger, Steven L; Menda, Shivali A; Fortune, Brad A; Gardiner, Stuart K; Demirel, Shaban

2017-02-01

To characterize the error of optical coherence tomography (OCT) measurements of retinal nerve fiber layer (RNFL) thickness when using automated retinal layer segmentation algorithms without manual refinement. Cross-sectional study. This study was set in a glaucoma clinical practice, and the dataset included 3490 scans from 412 eyes of 213 individuals with a diagnosis of glaucoma or glaucoma suspect. We used spectral domain OCT (Spectralis) to measure RNFL thickness in a 6-degree peripapillary circle, and exported the native "automated segmentation only" results. In addition, we exported the results after "manual refinement" to correct errors in the automated segmentation of the anterior (internal limiting membrane) and the posterior boundary of the RNFL. Our outcome measures included differences in RNFL thickness and glaucoma classification (i.e., normal, borderline, or outside normal limits) between scans with automated segmentation only and scans using manual refinement. Automated segmentation only resulted in a thinner global RNFL thickness (1.6 μm thinner, P < .001) when compared to manual refinement. When adjusted by operator, a multivariate model showed increased differences with decreasing RNFL thickness (P < .001), decreasing scan quality (P < .001), and increasing age (P < .03). Manual refinement changed 298 of 3486 (8.5%) of scans to a different global glaucoma classification, wherein 146 of 617 (23.7%) of borderline classifications became normal. Superior and inferior temporal clock hours had the largest differences. Automated segmentation without manual refinement resulted in reduced global RNFL thickness and overestimated the classification of glaucoma. Differences increased in eyes with a thinner RNFL thickness, older age, and decreased scan quality. Operators should inspect and manually refine OCT retinal layer segmentation when assessing RNFL thickness in the management of patients with glaucoma. Copyright © 2016 Elsevier Inc. All rights reserved.

Frequency doubling technique perimetry and spectral domain optical coherence tomography in patients with early glaucoma.

PubMed

Horn, F K; Mardin, C Y; Bendschneider, D; Jünemann, A G; Adler, W; Tornow, R P

2011-01-01

To assess the combined diagnostic power of frequency-doubling technique (FDT)-perimetry and retinal nerve fibre layer (RNFL) thickness measurements with spectral domain optical coherence tomography (SDOCT). The study included 330 experienced participants in five age-related groups: 77 'preperimetric' open-angle glaucoma (OAG) patients, 52 'early' OAG, 50 'moderate' OAG, 54 ocular hypertensive patients, and 97 healthy subjects. For glaucoma assessment in all subjects conventional perimetry, evaluation of fundus photographs, FDT-perimetry and RNFL thickness measurement with SDOCT was done. Glaucomatous visual field defects were classified using the Glaucoma Staging System. FDT evaluation used a published method with casewise calculation of an 'FDT-score', including all missed localized probability levels. SDOCT evaluation used mean RNFL thickness and a new individual SDOCT-score considering normal confidence limits in 32 sectors of a peripapillary circular scan. To examine the joined value of both methods a combined score was introduced. Significance of the difference between Receiver-operating-characteristic (ROC) curves was calculated for a specificity of 96%. Sensitivity in the preperimetric glaucoma group was 44% for SDOCT-score, 25% for FDT-score, and 44% for combined score, in the early glaucoma group 83, 81, and 89%, respectively, and in the moderate glaucoma group 94, 94, and 98%, respectively, all at a specificity of 96%. ROC performance of the newly developed combined score is significantly above single ROC curves of FDT-score in preperimetric and early OAG and above RNFL thickness in moderate OAG. Combination of function and morphology by using the FDT-score and the SDOCT-score performs equal or even better than each single method alone.

Frequency doubling technique perimetry and spectral domain optical coherence tomography in patients with early glaucoma

PubMed Central

Horn, F K; Mardin, C Y; Bendschneider, D; Jünemann, A G; Adler, W; Tornow, R P

2011-01-01

Purpose To assess the combined diagnostic power of frequency-doubling technique (FDT)-perimetry and retinal nerve fibre layer (RNFL) thickness measurements with spectral domain optical coherence tomography (SDOCT). Methods The study included 330 experienced participants in five age-related groups: 77 ‘preperimetric' open-angle glaucoma (OAG) patients, 52 ‘early' OAG, 50 ‘moderate' OAG, 54 ocular hypertensivepatients, and 97 healthy subjects. For glaucoma assessment in all subjects conventional perimetry, evaluation of fundus photographs, FDT-perimetry and RNFL thickness measurement with SDOCT was done. Glaucomatous visual field defects were classified using the Glaucoma Staging System. FDT evaluation used a published method with casewise calculation of an ‘FDT-score', including all missed localized probability levels. SDOCT evaluation used mean RNFL thickness and a new individual SDOCT-score considering normal confidence limits in 32 sectors of a peripapillary circular scan. To examine the joined value of both methods a combined score was introduced. Significance of the difference between Receiver-operating-characteristic (ROC) curves was calculated for a specificity of 96%. Results Sensitivity in the preperimetric glaucoma group was 44% for SDOCT-score, 25% for FDT-score, and 44% for combined score, in the early glaucoma group 83, 81, and 89%, respectively, and in the moderate glaucoma group 94, 94, and 98%, respectively, all at a specificity of 96%. ROC performance of the newly developed combined score is significantly above single ROC curves of FDT-score in preperimetric and early OAG and above RNFL thickness in moderate OAG. Conclusion Combination of function and morphology by using the FDT-score and the SDOCT-score performs equal or even better than each single method alone. PMID:21102494

Optical coherence tomography detects characteristic retinal nerve fiber layer thickness corresponding to band atrophy of the optic discs.

PubMed

Kanamori, Akiyasu; Nakamura, Makoto; Matsui, Noriko; Nagai, Azusa; Nakanishi, Yoriko; Kusuhara, Sentaro; Yamada, Yuko; Negi, Akira

2004-12-01

To analyze retinal nerve fiber layer (RNFL) thickness in eyes with band atrophy by use of optical coherence tomography (OCT) and to evaluate the ability of OCT to detect this characteristic pattern of RNFL loss. Cross-sectional, retrospective study. Thirty-four eyes of 18 patients with bitemporal hemianopia caused by optic chiasm compression by chiasmal tumors were studied. All eyes were divided into 3 groups according to visual field loss grading after Goldmann perimetry. Retinal nerve fiber layer thickness measurements with OCT. Retinal nerve fiber layer thickness around the optic disc was measured by OCT (3.4-mm diameter circle). Calculation of the changes in OCT parameters, including the horizontal (nasal + temporal quadrant RNFL thickness) and vertical values (superior + inferior quadrant RNFL thickness) was based on data from 160 normal eyes. Comparison between the 3 visual field grading groups was done with the analysis of variance test. The receiver operating characteristic (ROC) curve for the horizontal and vertical value were calculated, and the areas under the curve (AUC) were compared. Retinal nerve fiber layer thickness in eyes with band atrophy decreased in all OCT parameters. The reduction rate in average and temporal RNFL thickness and horizontal value was correlated with visual field grading. The AUC of horizontal value was 0.970+/-0.011, which was significantly different from AUC of vertical value (0.903+/-0.022). The degree of RNFL thickness reduction correlated with that of visual field defects. Optical coherence tomography was able to identify the characteristic pattern of RNFL loss in these eyes.

Ganglion cell loss in relation to visual disability in multiple sclerosis.

PubMed

Walter, Scott D; Ishikawa, Hiroshi; Galetta, Kristin M; Sakai, Reiko E; Feller, Daniel J; Henderson, Sam B; Wilson, James A; Maguire, Maureen G; Galetta, Steven L; Frohman, Elliot; Calabresi, Peter A; Schuman, Joel S; Balcer, Laura J

2012-06-01

We used high-resolution spectral-domain optical coherence tomography (SD-OCT) with retinal segmentation to determine how ganglion cell loss relates to history of acute optic neuritis (ON), retinal nerve fiber layer (RNFL) thinning, visual function, and vision-related quality of life (QOL) in multiple sclerosis (MS). Cross-sectional study. A convenience sample of patients with MS (n = 122; 239 eyes) and disease-free controls (n = 31; 61 eyes). Among MS eyes, 87 had a history of ON before enrollment. The SD-OCT images were captured using Macular Cube (200×200 or 512×128) and ONH Cube 200×200 protocols. Retinal layer segmentation was performed using algorithms established for glaucoma studies. Thicknesses of the ganglion cell layer/inner plexiform layer (GCL+IPL), RNFL, outer plexiform/inner nuclear layers (OPL+INL), and outer nuclear/photoreceptor layers (ONL+PRL) were measured and compared in MS versus control eyes and MS ON versus non-ON eyes. The relation between changes in macular thickness and visual disability was also examined. The OCT measurements of GCL+IPL and RNFL thickness; high contrast visual acuity (VA); low-contrast letter acuity (LCLA) at 2.5% and 1.25% contrast; on the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) and 10-Item Neuro-Ophthalmic Supplement composite score. Macular RNFL and GCL+IPL were significantly decreased in MS versus control eyes (P<0.001 and P = 0.001) and in MS ON versus non-ON eyes (P<0.001 for both measures). Peripapillary RNFL, macular RNFL, GCL+IPL, and the combination of macular RNFL+GCL+IPL were significantly correlated with VA (P≤0.001), 2.5% LCLA (P<0.001), and 1.25% LCLA (P≤0.001). Among OCT measurements, reductions in GCL+IPL (P<0.001), macular RNFL (P = 0.006), and the combination (macular RNFL+GCL+IPL; P<0.001) were most strongly associated with lower (worse) NEI-VFQ-25 and 10-Item Supplement QOL scores; GCL+IPL thinning was significant even accounting for macular RNFL thickness (P = 0.03 for GCL+IPL, P = 0.39 for macular RNFL). We demonstrated that GCL+IPL thinning is most significantly correlated with both visual function and vision-specific QOL in MS, and may serve as a useful structural marker of disease. Our findings parallel those of magnetic resonance imaging studies that show gray matter disease is a marker of neurologic disability in MS. Proprietary or commercial disclosure may be found after the references. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Retinal nerve fiber layer measurements by scanning laser polarimetry with enhanced corneal compensation in healthy subjects.

PubMed

Rao, Harsha L; Venkatesh, Chirravuri R; Vidyasagar, Kelli; Yadav, Ravi K; Addepalli, Uday K; Jude, Aarthi; Senthil, Sirisha; Garudadri, Chandra S

2014-12-01

To evaluate the (i) effects of biological (age and axial length) and instrument-related [typical scan score (TSS) and corneal birefringence] parameters on the retinal nerve fiber layer (RNFL) measurements and (ii) repeatability of RNFL measurements with the enhanced corneal compensation (ECC) protocol of scanning laser polarimetry (SLP) in healthy subjects. In a cross-sectional study, 140 eyes of 73 healthy subjects underwent RNFL imaging with the ECC protocol of SLP. Linear mixed modeling methods were used to evaluate the effects of age, axial length, TSS, and corneal birefringence on RNFL measurements. One randomly selected eye of 48 subjects from the cohort underwent 3 serial scans during the same session to determine the repeatability. Age significantly influenced all RNFL measurements. RNFL measurements decreased by 1 µm for every decade increase in age. TSS affected the overall average RNFL measurement (β=-0.62, P=0.003), whereas residual anterior segment retardance affected the superior quadrant measurement (β=1.14, P=0.01). Axial length and corneal birefringence measurements did not influence RNFL measurements. Repeatability, as assessed by the coefficient of variation, ranged between 1.7% for the overall average RNFL measurement and 11.4% for th nerve fiber indicator. Age significantly affected all RNFL measurements with the ECC protocol of SLP, whereas TSS and residual anterior segment retardance affected the overall average and the superior average RNFL measurements, respectively. Axial length and corneal birefringence measurements did not influence any RNFL measurements. RNFL measurements had good intrasession repeatability. These results are important while evaluating the change in structural measurements over time in glaucoma patients.

Retinal nerve fiber layer thickness in normals measured by spectral domain OCT.

PubMed

Bendschneider, Delia; Tornow, Ralf P; Horn, Folkert K; Laemmer, Robert; Roessler, Christopher W; Juenemann, Anselm G; Kruse, Friedrich E; Mardin, Christian Y

2010-09-01

To determine normal values for peripapillary retinal nerve fiber layer thickness (RNFL) measured by spectral domain Optical Coherence Tomography (SOCT) in healthy white adults and to examine the relationship of RNFL with age, gender, and clinical variables. The peripapillary RNFL of 170 healthy patients (96 males and 74 females, age 20 to 78 y) was imaged with a high-resolution SOCT (Spectralis HRA+OCT, Heidelberg Engineering) in an observational cross-sectional study. RNFL thickness was measured around the optic nerve head using 16 automatically averaged, consecutive circular B-scans with 3.4-mm diameter. The automatically segmented RNFL thickness was divided into 32 segments (11.25 degrees each). One randomly selected eye per subject entered the study. Mean RNFL thickness in the study population was 97.2 ± 9.7 μm. Mean RNFL thickness was significantly negatively correlated with age (r = -0.214, P = 0.005), mean RNFL decrease per decade was 1.90 μm. As age dependency was different in different segments, age-correction of RNFL values was made for all segments separately. Age-adjusted RNFL thickness showed a significant correlation with axial length (r = -0.391, P = 0.001) and with refractive error (r = 0.396, P<0.001), but not with disc size (r = 0.124). Normal RNFL results with SOCT are comparable to those reported with time-domain OCT. In accordance with the literature on other devices, RNFL thickness measured with SOCT was significantly correlated with age and axial length. For creating a normative database of SOCT RNFL values have to be age adjusted.

Evaluation of a New Scoring System for Retinal Nerve Fiber Layer Photography Using HRA1 in 964 Eyes

PubMed Central

Hong, Samin; Moon, Jong Wook; Ha, Seung Joo; Kim, Chan Yun; Seong, Gong Je

2007-01-01

Purpose To evaluate retinal nerve fiber layer (RNFL) defect by a new scoring system for RNFL photography using the Heidelberg Retina Angiograph 1 (HRA1). Methods This retrospective study included 128 healthy eyes and 836 primary open-angle glaucoma eyes. The RNFL photography using HRA1 was interpreted using a new scoring system, and correlated with visual field indices of standard automated perimetry (SAP). Using the presence of RNFL defect, darkness, width, and location, we established the new scoring system of RNFL photos. Results The mean RNFL defect score I in the early, moderate, severe, and control groups were 7.3, 9.2, 10.4, and 3.6, respectively. The mean RNFL defect score II in the early, moderate, severe, and control groups were 14.5, 28.5, 43.4, and 3.4, respectively. Correlations between the RNFL defect score II and the mean deviation of SAP was the strongest of the various combinations (r=-0.675, P<.001). Conclusions Using a new scoring system, we propose a method for semi-quantitative interpretation of RNFL photographs. This scoring system may be helpful to distinguish between normal and glaucomatous eyes, and the score is associated with the severity of visual field loss. PMID:18063886

Diagnostic performance of optical coherence tomography ganglion cell--inner plexiform layer thickness measurements in early glaucoma.

PubMed

Mwanza, Jean-Claude; Budenz, Donald L; Godfrey, David G; Neelakantan, Arvind; Sayyad, Fouad E; Chang, Robert T; Lee, Richard K

2014-04-01

To evaluate the glaucoma diagnostic performance of ganglion cell inner-plexiform layer (GCIPL) parameters used individually and in combination with retinal nerve fiber layer (RNFL) or optic nerve head (ONH) parameters measured with Cirrus HD-OCT (Carl Zeiss Meditec, Inc, Dublin, CA). Prospective cross-sectional study. Fifty patients with early perimetric glaucoma and 49 age-matched healthy subjects. Three peripapillary RNFL and 3 macular GCIPL scans were obtained in 1 eye of each participant. A patient was considered glaucomatous if at least 2 of the 3 RNFL or GCIPL scans had the average or at least 1 sector measurement flagged at 1% to 5% or less than 1%. The diagnostic performance was determined for each GCIPL, RNFL, and ONH parameter as well as for binary or-logic and and-logic combinations of GCIPL with RNFL or ONH parameters. Sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR). Among GCIPL parameters, the minimum had the best diagnostic performance (sensitivity, 82.0%; specificity, 87.8%; PLR, 6.69; and NLR, 0.21). Inferior quadrant was the best RNFL parameter (sensitivity, 74%; specificity, 95.9%; PLR, 18.13; and NLR, 0.27), as was rim area (sensitivity, 68%; specificity, 98%; PLR, 33.3; and NLR, 0.33) among ONH parameters. The or-logic combination of minimum GCIPL and average RNFL provided the overall best diagnostic performance (sensitivity, 94%; specificity, 85.7%; PRL, 6.58; and NLR, 0.07) as compared with the best RNFL, best ONH, and best and-logic combination (minimum GCIPL and inferior quadrant RNFL; sensitivity, 64%; specificity, 100%; PLR, infinity; and NPR, 0.36). The binary or-logic combination of minimum GCIPL and average RNFL or rim area provides better diagnostic performances than those of and-logic combinations or best single GCIPL, RNFL, or ONH parameters. This finding may be clinically valuable for the diagnosis of early glaucoma. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Comparing the Rates of Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Loss in Healthy Eyes and in Glaucoma Eyes.

PubMed

Hammel, Naama; Belghith, Akram; Weinreb, Robert N; Medeiros, Felipe A; Mendoza, Nadia; Zangwill, Linda M

2017-06-01

To compare the rates of circumpapillary retinal nerve fiber layer (RNFL) and macular retinal ganglion cell-inner plexiform layer (GCIPL) change over time in healthy and glaucoma eyes. Cohort study. The rates of circumpapillary RNFL and macular GCIPL loss in 28 healthy subjects and 97 glaucoma subjects from the Diagnostic Innovations in Glaucoma Study (DIGS) were compared using mixed-effects models. The median follow-up time and number of visits were 1.7 years and 6 visits and 3.2 years and 7 visits for healthy and glaucoma eyes, respectively. Significant rates of loss of both global circumpapillary RNFL and average macular GCIPL thickness were detectable in early and moderate glaucoma eyes; in severe glaucoma eyes, rates of average macular GCIPL loss were significant, but rates of global circumpapillary RNFL loss were not. In glaucoma eyes, mean rates of global circumpapillary RNFL thickness change (-0.98 μm/year [95% confidence interval (CI), -1.20 to -0.76]) and normalized global circumpapillary RNFL change (-1.7%/year [95% CI, -2.1 to -1.3]) were significantly faster than average macular GCIPL change (-0.57 μm/year [(95% CI, -0.73 to -0.41]) and normalized macular GCIPL change (-1.3%/year [95% CI, -1.7 to -0.9]). The rates of global and inferior RNFL change were weakly correlated with global and inferior macular GCIPL change (r ranges from 0.16 to 0.23, all P < .05). In this cohort, the rate of circumpapillary RNFL thickness change was faster than macular GCIPL change for glaucoma eyes. Global circumpapillary RNFL thickness loss was detectable in early and moderate glaucoma, and average macular GCIPL thickness loss was detectable in early, moderate, and severe glaucoma, suggesting that structural changes can be detected in severe glaucoma. Copyright © 2017 Elsevier Inc. All rights reserved.

High resolution retinal scanning reveals regional structural differences between MS and NMOSD optic neuritis regardless of antibody status.

PubMed

Bertsch-Gout, Marcel; Loeb, Richard; Finch, Ashley K; Javed, Adil; Bernard, Jacqueline

2018-01-15

There is a need for biomarkers that can classify optic neuritis (ON) attacks as belonging to either neuromyelitis optica spectrum disorder with optic neuritis (NMOSD-ON) or relapsing remitting multiple sclerosis with optic neuritis (MS-ON). This study uses spectral domain optical coherence tomography (SD-OCT) data to perform a preliminary contrast between NMOSD-ON and MS-ON by analyzing peripapillary retinal nerve fiber layer and intra-macular layer patterns of injury. In this cross-sectional study, we used SD-OCT to obtain peripapillary retinal nerve fiber layer and intra-macular layer data for 26 NMOSD-ON, 25 MS-ON, and 26 healthy control (HC) age-matched eyes. Additionally, sub-comparisons compared 11 NMOSD-ON eyes that were seronegative for IgG antibodies against aquaporin 4 (NMOSD-ON (-)) and 16 NMOSD-ON eyes that were seropositive (NMOSD-ON (+)) to age-matched MS-ON eyes. Layer thicknesses were assessed using an automated algorithm and were then statistically compared using generalized estimating equations to account for inter-eye correlations. Selective thinning was found in the pRNFL, mRNFL, and GCL in NMOSD-ON compared to MS-ON. Thinning in the pRNFL nasal sector was found to persist in both NMOSD-ON (-) (P=0.017) and NMOSD-ON (+) (P=0.021) compared to MS-ON. Thinning in the mRNFL temporal sector was found to persist in NMOSD-ON (+) compared to MS-ON. Diffuse thinning was found in the pRNFL, mRNFL, GCL and IPL in NMOSD-ON compared to HC, and while diffuse thinning was also found in the GCL and IPL in MS-ON compared to HC, selective thinning was found in the pRNFL and mRNFL. The nasal region of the pRNFL may be capable of distinguishing between NMOSD-ON and MS-ON regardless of antibody status. Additionally, NMOSD-ON may cause more profound nasal axonal and inferior arcuate neuronal degeneration compared to MS-ON. Copyright © 2017 Elsevier B.V. All rights reserved.

Cone dysfunctions in retinitis pigmentosa with retinal nerve fiber layer thickening

PubMed Central

Sobacı, Güngör; Özge, Gökhan; Gündoğan, Fatih Ç

2012-01-01

Purpose To investigate whether or not thicker retinal nerve fiber layer (RNFL) in retinitis pigmentosa (RP) patients relates to functional abnormalities of the photoreceptors. Methods Optical coherence tomography-based RNFL thickness was measured by Stratus-3™ (Zeiss, Basel, Switzerland) optical coherence tomography and electroretinogram (ERG) recordings made using the RETI-port® system (Roland, Wiesbaden, Germany) in 27 patients with retinitis pigmentosa and in 30 healthy subjects. Results Photopic ERG b-wave amplitude, cone ERG b-wave latency, 30 Hz flicker amplitude, and 30 Hz flicker latency had significant correlations to the RNFL-temporal (r = −0.55, P = 0.004, r = 0.68, P = 0.001, r = −0.65, P = 0.001, and r = −0.52, P = 0.007, respectively). Eyes with thicker RNFL (ten eyes) differed significantly from those with thinner RNFL (eight eyes) regarding cone ERG b-wave latency values only (P = 0.001). Conclusion Thicker RNFL in patients with retinitis pigmentosa may be associated with functional abnormality of the cone system. PMID:22536039

Cone dysfunctions in retinitis pigmentosa with retinal nerve fiber layer thickening.

PubMed

Sobacı, Güngör; Ozge, Gökhan; Gündoğan, Fatih Ç

2012-01-01

To investigate whether or not thicker retinal nerve fiber layer (RNFL) in retinitis pigmentosa (RP) patients relates to functional abnormalities of the photoreceptors. Optical coherence tomography-based RNFL thickness was measured by Stratus-3™ (Zeiss, Basel, Switzerland) optical coherence tomography and electroretinogram (ERG) recordings made using the RETI-port(®) system (Roland, Wiesbaden, Germany) in 27 patients with retinitis pigmentosa and in 30 healthy subjects. Photopic ERG b-wave amplitude, cone ERG b-wave latency, 30 Hz flicker amplitude, and 30 Hz flicker latency had significant correlations to the RNFL-temporal (r = -0.55, P = 0.004, r = 0.68, P = 0.001, r = -0.65, P = 0.001, and r = -0.52, P = 0.007, respectively). Eyes with thicker RNFL (ten eyes) differed significantly from those with thinner RNFL (eight eyes) regarding cone ERG b-wave latency values only (P = 0.001). Thicker RNFL in patients with retinitis pigmentosa may be associated with functional abnormality of the cone system.

Comparison of RNFL thickness and RPE-normalized RNFL attenuation coefficient for glaucoma diagnosis

NASA Astrophysics Data System (ADS)

Vermeer, K. A.; van der Schoot, J.; Lemij, H. G.; de Boer, J. F.

2013-03-01

Recently, a method to determine the retinal nerve fiber layer (RNFL) attenuation coefficient, based on normalization on the retinal pigment epithelium, was introduced. In contrast to conventional RNFL thickness measures, this novel measure represents a scattering property of the RNFL tissue. In this paper, we compare the RNFL thickness and the RNFL attenuation coefficient on 10 normal and 8 glaucomatous eyes by analyzing the correlation coefficient and the receiver operator curves (ROCs). The thickness and attenuation coefficient showed moderate correlation (r=0.82). Smaller correlation coefficients were found within normal (r=0.55) and glaucomatous (r=0.48) eyes. The full separation between normal and glaucomatous eyes based on the RNFL attenuation coefficient yielded an area under the ROC (AROC) of 1.0. The AROC for the RNFL thickness was 0.9875. No statistically significant difference between the two measures was found by comparing the AROC. RNFL attenuation coefficients may thus replace current RNFL thickness measurements or be combined with it to improve glaucoma diagnosis.

Relationship Between Optic Nerve Appearance and Retinal Nerve Fiber Layer Thickness as Explored with Spectral Domain Optical Coherence Tomography

PubMed Central

Aleman, Tomas S.; Huang, Jiayan; Garrity, Sean T.; Carter, Stuart B.; Aleman, Wendy D.; Ying, Gui-shuang; Tamhankar, Madhura A.

2014-01-01

Purpose To study the relationship between the appearance of the optic nerve and the retinal nerve fiber layer (RNFL) thickness determined by spectral domain optical coherence tomography (OCT). Methods Records from patients with spectral domain-OCT imaging in a neuro-ophthalmology practice were reviewed. Eyes with glaucoma/glaucoma suspicion, macular/optic nerve edema, pseudophakia, and with refractive errors > 6D were excluded. Optic nerve appearance by slit lamp biomicroscopy was related to the RNFL thickness by spectral domain-OCT and to visual field results. Results Ninety-one patients (176 eyes; mean age: 49 ± 15 years) were included. Eighty-three eyes (47%) showed optic nerve pallor; 89 eyes (50.6%) showed RNFL thinning (sectoral or average peripapillary). Average peripapillary RNFL thickness in eyes with pallor (mean ± SD = 76 ± 17 μm) was thinner compared to eyes without pallor (91 ± 14 μm, P < 0.001). Optic nerve pallor predicted RNFL thinning with a sensitivity of 69% and a specificity of 75%. Optic nerve appearance predicted RNFL thinning (with a sensitivity and specificity of 81%) when RNFL had thinned by ∼ 40%. Most patients with pallor had RNFL thinning with (66%) or without (25%) visual field loss; the remainder had normal RNFL and fields (5%) or with visual field abnormalities (4%). Conclusions Optic nerve pallor as a predictor of RNFL thinning showed fair sensitivity and specificity, although it is optimally sensitive/specific only when substantial RNFL loss has occurred. Translational Relevance Finding an acceptable relationship between the optic nerve appearance by ophthalmoscopy and spectral domain-OCT RNFL measures will help the clinician's interpretation of the information provided by this technology, which is gaining momentum in neuro-ophthalmic research. PMID:25374773

Bilateral Neuroretinitis in Cat Scratch Disease with Exudative, Obliterative Vasculitis in the Optic Disc.

PubMed

Tagawa, Yoshiaki; Suzuki, Yasuo; Sakaguchi, Takatoshi; Endoh, Hiroki; Yokoi, Masahiko; Kase, Manabu

2014-01-01

A 29-year-old fisherman exhibited optic disc oedema and peripapillary retinal detachment in the right eye, whereas in the left eye, optic atrophy and intraretinal exudates were already observed on first examination. About 6 months earlier, he noticed blurred vision of the left eye but took no medication. Visual acuity was 0.4 OD and 0.01 OS. Perimetry showed a large lower-half field defect with sparing 10° central field in the right eye and a large central scotoma in the left eye. Fluorescein angiography showed existence of arteriole or capillary nonperfusion and hyperpermeability of surrounding capillaries. Since serological examinations showed positive Bartonella immunoglobulin G (IgG) and other causes of neuroretinitis (NR) were excluded, NR in the present case was caused by cat scratch disease (CSD). Optic atrophy appeared 2 weeks after onset. Optical coherence tomography 13 weeks after onset revealed severe loss of retinal nerve fibre layer (RNFL) superior and nasal to the optic disc in both eyes and temporal in the left eye. Visual acuity of the right eye improved to 1.2 by the treatment, whereas visual field defects were persistent. CSD-NR in the present case developed abrupt appearance of optic atrophy with severe RNFL loss in the right eye, which was elicited by exudative, obliterative vasculitis in the superficial layer of the optic disc.

Changes in Macular Retinal Layers and Peripapillary Nerve Fiber Layer Thickness after 577-nm Pattern Scanning Laser in Patients with Diabetic Retinopathy

PubMed Central

Shin, Ji Soo

2017-01-01

Purpose The aim of this study was to evaluate the changes in thickness of each macular retinal layer, the peripapillary retinal nerve fiber layer (RNFL), and central macular thickness (CMT) after 577-nm pattern scanning laser (PASCAL) photocoagulation in patients with diabetic retinopathy. Methods This retrospective study included 33 eyes with diabetic retinopathy that underwent 577-nm PASCAL photocoagulation. Each retinal layer thickness, peripapillary RNFL thickness, and CMT were measured by spectral-domain optical coherence tomography before 577-nm PASCAL photocoagulation, as well as at 1, 6, and 12 months after 577-nm PASCAL photocoagulation. Computerized intraretinal segmentation of optical coherence tomography was performed to identify the thickness of each retinal layer. Results The average thickness of the RNFL, ganglion cell layer, inner plexiform layer, inner nuclear layer, inner retinal layer, and CMT at each follow-up increased significantly from baseline (p < 0.001), whereas that of the retinal pigment epithelium at each follow-up decreased significantly from baseline (p < 0.001). The average thickness of the peripapillary RNFL increased significantly at one month (p < 0.001). This thickness subsequently recovered to 7.48 µm, and there were no significant changes at six or 12 months compared to baseline (p > 0.05). Conclusions Each macular retinal layer and CMT had a tendency to increase for one year after 577-nm PASCAL photocoagulation, whereas the average thickness of retinal pigment epithelium decreased at one-year follow-up compared to the baseline. Although an increase in peripapillary RNFL thickness was observed one month after 577-nm PASCAL photocoagulation, there were no significant changes at the one-year follow-up compared to the baseline. PMID:29022292

Changes in Macular Retinal Layers and Peripapillary Nerve Fiber Layer Thickness after 577-nm Pattern Scanning Laser in Patients with Diabetic Retinopathy.

PubMed

Shin, Ji Soo; Lee, Young Hoon

2017-12-01

The aim of this study was to evaluate the changes in thickness of each macular retinal layer, the peripapillary retinal nerve fiber layer (RNFL), and central macular thickness (CMT) after 577-nm pattern scanning laser (PASCAL) photocoagulation in patients with diabetic retinopathy. This retrospective study included 33 eyes with diabetic retinopathy that underwent 577-nm PASCAL photocoagulation. Each retinal layer thickness, peripapillary RNFL thickness, and CMT were measured by spectral-domain optical coherence tomography before 577-nm PASCAL photocoagulation, as well as at 1, 6, and 12 months after 577-nm PASCAL photocoagulation. Computerized intraretinal segmentation of optical coherence tomography was performed to identify the thickness of each retinal layer. The average thickness of the RNFL, ganglion cell layer, inner plexiform layer, inner nuclear layer, inner retinal layer, and CMT at each follow-up increased significantly from baseline (p < 0.001), whereas that of the retinal pigment epithelium at each follow-up decreased significantly from baseline (p < 0.001). The average thickness of the peripapillary RNFL increased significantly at one month (p < 0.001). This thickness subsequently recovered to 7.48 μm, and there were no significant changes at six or 12 months compared to baseline (p > 0.05). Each macular retinal layer and CMT had a tendency to increase for one year after 577-nm PASCAL photocoagulation, whereas the average thickness of retinal pigment epithelium decreased at one-year follow-up compared to the baseline. Although an increase in peripapillary RNFL thickness was observed one month after 577-nm PASCAL photocoagulation, there were no significant changes at the one-year follow-up compared to the baseline. © 2017 The Korean Ophthalmological Society

Effect of improper scan alignment on retinal nerve fiber layer thickness measurements using Stratus optical coherence tomograph.

PubMed

Vizzeri, Gianmarco; Bowd, Christopher; Medeiros, Felipe A; Weinreb, Robert N; Zangwill, Linda M

2008-08-01

Misalignment of the Stratus optical coherence tomograph scan circle placed by the operator around the optic nerve head (ONH) during each retinal nerve fiber layer (RNFL) examination can affect the instrument reproducibility and its theoretical ability to detect true structural changes in the RNFL thickness over time. We evaluated the effect of scan circle placement on RNFL measurements. Observational clinical study. Sixteen eyes of 8 normal participants were examined using the Stratus optical coherence tomograph Fast RNFL thickness acquisition protocol (software version 4.0.7; Carl Zeiss Meditec, Dublin, CA). Four consecutive images were taken by the same operator with the circular scan centered on the optic nerve head. Four images each with the scan displaced superiorly, inferiorly, temporally, and nasally were also acquired. Differences in average and sectoral RNFL thicknesses were determined. For the centered scans, the coefficients of variation (CV) and the intraclass correlation coefficient for the average RNFL thickness measured were calculated. When the average RNFL thickness of the centered scans was compared with the average RNFL thickness of the displaced scans individually using analysis of variance with post-hoc analysis, no difference was found between the average RNFL thickness of the nasally (105.2 microm), superiorly (106.2 microm), or inferiorly (104.1 microm) displaced scans and the centered scans (106.4 microm). However, a significant difference (analysis of variance with Dunnett's test: F=8.82, P<0.0001) was found between temporally displaced scans (115.8 microm) and centered scans. Significant differences in sectoral RNFL thickness measurements were found between centered and each displaced scan. The coefficient of variation for average RNFL thickness was 1.75% and intraclass correlation coefficient was 0.95. In normal eyes, average RNFL thickness measurements are robust and similar with significant superior, inferior, and nasal scan displacement, but average RNFL thickness is greater when scans are displaced temporally. Parapapillary scan misalignment produces significant changes in RNFL assessment characterized by an increase in measured RNFL thickness in the quadrant in which the scan is closer to the disc, and a significant decrease in RNFL thickness in the quadrant in which the scan is displaced further from the optic disc.

Diagnostic Value of Ganglion Cell-Inner Plexiform Layer Thickness in Glaucoma With Superior or Inferior Visual Hemifield Defects.

PubMed

Kim, Ho Soong; Yang, Heon; Lee, Tae Heon; Lee, Kyung Heon

2016-06-01

To determine the diagnostic value of the ganglion cell-inner plexiform layer (GCIPL) thickness in glaucomatous eyes with superior or inferior visual hemifield defects. Eighty-five patients with glaucoma (42 isolated superior hemifield defects and 43 isolated inferior hemifield defects) and 46 normal subjects were enrolled. All patients underwent Cirrus high-definition optical coherence tomography and standard automated perimetry. The area under the receiver operating characteristic curve (AUC) was calculated to determine the diagnostic ability of the GCIPL and peripapillary retinal nerve fiber layer (pRNFL). In the superior hemifield defect glaucoma group, the best parameters for discriminating normal eyes from glaucomatous eyes were the inferotemporal GCIPL thickness (0.942), inferior quadrant RNFL thickness (0.974), and 7 o'clock sector RNFL thickness (0.999). For diagnosing inferior hemifield defect glaucoma, the AUCs of all GCIPL parameters (0.331 to 0.702) were significantly lower than that of the superior quadrant RNFL thickness (0.866, P<0.05). The diagnostic ability of GCIPL parameters was similar to that of the pRNFL parameters in superior hemifield defect glaucoma. However, the diagnostic performance of the GCIPL parameters was significantly inferior to those of the pRNFL parameters in eyes with inferior hemifield defect glaucoma.

Retinal Layers Measurements following Silicone Oil Tamponade for Retinal Detachment Surgery.

PubMed

Jurišić, Darija; Geber, Mia Zorić; Ćavar, Ivan; Utrobičić, Dobrila Karlica

2017-12-19

This study aimed to investigate the influence of silicone oil on the retinal nerve fiber layer (RNFL) thickness in patients with primary rhegmatogenous retinal detachment who underwent vitreoretinal surgery. The study included 47 patients (eyes), who underwent a pars plana vitrectomy with the silicone oil tamponade. The control group included unoperated eye of all participants. Spectral-domain optical coherence tomography (SD-OCT) was used for the measurements of peripapilar and macular RNFL thickness. The average peripapillary RNFL thickness was significantly higher in the silicone oil filled eyes during endotamponade and after its removal. The eyes with elevated IOP had less thickening of the RNFL in comparison to the eyes with normal IOP. Central macular thickness and macular volume were decreased in the silicone oil filled eyes in comparison to the control eyes. In conclusion, silicone oil caused peripapilar RNFL thickening in the vitrectomized eyes during endotamponade and after silicone oil removal.

Normative Database and Color-code Agreement of Peripapillary Retinal Nerve Fiber Layer and Macular Ganglion Cell-inner Plexiform Layer Thickness in a Vietnamese Population.

PubMed

Perez, Claudio I; Chansangpetch, Sunee; Thai, Andy; Nguyen, Anh-Hien; Nguyen, Anwell; Mora, Marta; Nguyen, Ngoc; Lin, Shan C

2018-06-05

Evaluate the distribution and the color probability codes of the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) thickness in a healthy Vietnamese population and compare them with the original color-codes provided by the Cirrus spectral domain OCT. Cross-sectional study. We recruited non-glaucomatous Vietnamese subjects and constructed a normative database for peripapillary RNFL and macular GCIPL thickness. The probability color-codes for each decade of age were calculated. We evaluated the agreement with Kappa coefficient (κ) between OCT color probability codes with Cirrus built-in original normative database and the Vietnamese normative database. 149 eyes of 149 subjects were included. The mean age of enrollees was 60.77 (±11.09) years, with a mean spherical equivalent of +0.65 (±1.58) D and mean axial length of 23.4 (±0.87) mm. Average RNFL thickness was 97.86 (±9.19) microns and average macular GCIPL was 82.49 (±6.09) microns. Agreement between original and adjusted normative database for RNFL was fair for average and inferior quadrant (κ=0.25 and 0.2, respectively); and good for other quadrants (range: κ=0.63-0.73). For macular GCIPL κ agreement ranged between 0.39 and 0.69. After adjusting with the normative Vietnamese database, the percent of yellow and red color-codes increased significantly for peripapillary RNFL thickness. Vietnamese population has a thicker RNFL in comparison with Cirrus normative database. This leads to a poor color-code agreement in average and inferior quadrant between the original and adjusted database. These findings should encourage to create a peripapillary RNFL normative database for each ethnicity.

Scanning laser polarimetry retinal nerve fiber layer thickness measurements after LASIK.

PubMed

Zangwill, Linda M; Abunto, Teresa; Bowd, Christopher; Angeles, Raymund; Schanzlin, David J; Weinreb, Robert N

2005-02-01

To compare retinal nerve fiber layer (RNFL) thickness measurements before and after LASIK. Cohort study. Twenty participants undergoing LASIK and 14 normal controls. Retinal nerve fiber layer thickness was measured before LASIK and approximately 3 months after surgery in one eye each of 20 patients using a scanning laser polarimeter (GDx Nerve Fiber Analyzer) with fixed corneal compensation (FCC), one with variable corneal compensation (GDx VCC), and optical coherence tomography (OCT). Fourteen normal controls also were tested at baseline and approximately 3 months later. Retinal nerve fiber layer thicknesses measured with the GDx FCC, GDx VCC, and OCT. At baseline, mean (95% confidence interval [CI]) RNFL thicknesses for the GDx FCC, GDx VCC, and OCT were 78.1 microm (72.2-83.9), 54.3 microm (52.7-56.0), and 96.8 microm (93.2-100.5), respectively. In both LASIK and control groups, there were no significant changes between baseline and follow-up examinations in GDx VCC and OCT RNFL thickness measurements globally or in the superior and inferior quadrants (mean change, <5 microm for each instrument). In the control group, there also was no significant change in GDx FCC measurements between baseline and follow-up. In LASIK patients, significant reductions were observed in GDx FCC RNFL measurements. Average absolute values of the mean (95% CI) change in thickness were 12.4 microm (7.7-17.2), 15.3 microm (9.6-20.9), and 12.9 microm (7.6-18.1) for GDx FCC RNFL measurements superiorly, inferiorly, and globally, respectively (all Ps < or = 0.001). LASIK does not seem to change RNFL thickness. Reduction in GDx FCC RNFL thickness measurements after LASIK is a measurement artifact and is most likely due to erroneous compensation for corneal birefringence. With scanning laser polarimetry, it is mandatory to compensate individually for change in corneal birefringence after LASIK to ensure accurate RNFL assessment.

Diagnostic Capability of Peripapillary Three-dimensional Retinal Nerve Fiber Layer Volume for Glaucoma Using Optical Coherence Tomography Volume Scans.

PubMed

Khoueir, Ziad; Jassim, Firas; Poon, Linda Yi-Chieh; Tsikata, Edem; Ben-David, Geulah S; Liu, Yingna; Shieh, Eric; Lee, Ramon; Guo, Rong; Papadogeorgou, Georgia; Braaf, Boy; Simavli, Huseyin; Que, Christian; Vakoc, Benjamin J; Bouma, Brett E; de Boer, Johannes F; Chen, Teresa C

2017-10-01

To determine the diagnostic capability of peripapillary 3-dimensional (3D) retinal nerve fiber layer (RNFL) volume measurements from spectral-domain optical coherence tomography (OCT) volume scans for open-angle glaucoma (OAG). Assessment of diagnostic accuracy. Setting: Academic clinical setting. Total of 180 patients (113 OAG and 67 normal subjects). One eye per subject was included. Peripapillary 3D RNFL volumes were calculated for global, quadrant, and sector regions, using 4 different-size annuli. Peripapillary 2D RNFL thickness circle scans were also obtained. Area under the receiver operating characteristic curve (AUROC) values, sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios. Among all 2D and 3D RNFL parameters, best diagnostic capability was associated with inferior quadrant 3D RNFL volume of the smallest annulus (AUROC value 0.977). Otherwise, global 3D RNFL volume AUROC values were comparable to global 2D RNFL thickness AUROC values for all 4 annulus sizes (P values: .0593 to .6866). When comparing the 4 annulus sizes for global RNFL volume, the smallest annulus had the best AUROC values (P values: .0317 to .0380). The smallest-size annulus may have the best diagnostic potential, partly owing to having no areas excluded for being larger than the 6 × 6 mm 2 scanned region. Peripapillary 3D RNFL volume showed excellent diagnostic performance for detecting glaucoma. Peripapillary 3D RNFL volume parameters have the same or better diagnostic capability compared to peripapillary 2D RNFL thickness measurements, although differences were not statistically significant. Copyright © 2017 Elsevier Inc. All rights reserved.

Presence of Peripheral Neuropathy Is Associated With Progressive Thinning of Retinal Nerve Fiber Layer in Type 1 Diabetes.

PubMed

Dehghani, Cirous; Srinivasan, Sangeetha; Edwards, Katie; Pritchard, Nicola; Russell, Anthony W; Malik, Rayaz A; Efron, Nathan

2017-05-01

Reduced retinal nerve fiber layer (RNFL) thickness has been demonstrated in patients with diabetic peripheral neuropathy (DPN) in cross-sectional studies. This prospective study defines longitudinal alterations to the RNFL thickness in individuals with type 1 diabetes without (DPN-ve) and with (DPN+ve) DPN and in relation to risk factors for nerve damage. A cohort of 105 individuals with type 1 diabetes (20% DPN+ve) with predominantly mild or no retinopathy and no previous retinal photocoagulation underwent spectral-domain optical coherence tomography (SD-OCT) at baseline, 2 years, and 4 years. SD-OCT scans were acquired at 3.45-mm diameter around the optic nerve head and the overall RNFL and RNFL in the nasal, superior, temporal, and inferior quadrants were quantified. By including serial quantified RNFL parameters, linear mixed models were applied to assess the change in RNFL thickness over time and to explore the associations with other clinical variables. There was a significant decline in the overall RNFL thickness (-0.7 μm/y, P = 0.02) and RNFL in the superior quadrant (-1.9 μm/y, P < 0.01) in the DPN+ve group compared with DPN-ve group. The overall RNFL thickness and RNFL in the superior and nasal quadrants were inversely associated with age (β = -0.29, -0.41, and -0.29, respectively; P ≤ 0.02). Sex, retinopathy, diabetes duration, hemoglobin A1c, lipid profile, blood pressure, cigarette use, alcohol consumption, and body mass index did not show any significant effects (P > 0.05). Individuals with DPN showed a progressive RNFL thinning overall and in the superior quadrant, which was more pronounced in older individuals. There may be common pathways for retinal and peripheral neurodegeneration that are independent of conventional DPN risk factors.

Ganglion cell-inner plexiform layer and retinal nerve fiber layer thickness according to myopia and optic disc area: a quantitative and three-dimensional analysis.

PubMed

Seo, Sam; Lee, Chong Eun; Jeong, Jae Hoon; Park, Ki Ho; Kim, Dong Myung; Jeoung, Jin Wook

2017-03-11

To determine the influences of myopia and optic disc size on ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (RNFL) thickness profiles obtained by spectral domain optical coherence tomography (OCT). One hundred and sixty-eight eyes of 168 young myopic subjects were recruited and assigned to one of three groups according to their spherical equivalent (SE) values and optic disc area. All underwent Cirrus HD-OCT imaging. The influences of myopia and optic disc size on the GCIPL and RNFL thickness profiles were evaluated by multiple comparisons and linear regression analysis. Three-dimensional surface plots of GCIPL and RNFL thickness corresponding to different combinations of myopia and optic disc size were constructed. Each of the quadrant RNFL thicknesses and their overall average were significantly thinner in high myopia compared to low myopia, except for the temporal quadrant (all Ps ≤0.003). The average and all-sectors GCIPL were significantly thinner in high myopia than in moderate- and/or low-myopia (all Ps ≤0.002). The average OCT RNFL thickness was correlated significantly with SE (0.81 μm/diopter, P < 0.001), axial length (-1.44 μm/mm, P < 0.001), and optic disc area (5.35 μm/mm 2 , P < 0.001) by linear regression analysis. As for the OCT GCIPL parameters, average GCIPL thickness showed a significant correlation with SE (0.84 μm/diopter, P < 0.001) and axial length (-1.65 μm/mm, P < 0.001). There was no significant correlation of average GCIPL thickness with optic disc area. Three-dimensional curves showed that larger optic discs were associated with increased average RNFL thickness and that more-myopic eyes were associated with decreased average GCIPL and RNFL thickness. Myopia can significantly affect GCIPL and RNFL thickness profiles, and optic disc size has a significant influence on RNFL thickness. The current OCT maps employed in the evaluation of glaucoma should be analyzed in consideration of refractive status and optic disc size.

Correlation of Retinal Nerve Fiber Layer Thickness and Visual Fields in Glaucoma: A broken stick model

PubMed Central

Alasil, Tarek; Wang, Kaidi; Yu, Fei; Field, Matthew G.; Lee, Hang; Baniasadi, Neda; de Boer, Johannes F.; Coleman, Anne L.; Chen, Teresa C.

2015-01-01

Purpose To determine the retinal nerve fiber layer (RNFL) thickness at which visual field (VF) damage becomes detectable and associated with structural loss. Design Retrospective cross-sectional study. Methods Eighty seven healthy and 108 glaucoma subjects (one eye per subject) were recruited from an academic institution. All patients had VF examinations (Swedish Interactive Threshold Algorithm 24-2 test of the Humphrey visual field analyzer 750i; Carl Zeiss Meditec, Dublin, CA) and spectral domain optical coherence tomography RNFL scans (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Comparison of RNFL thicknesses values with VF threshold values showed a plateau of VF threshold values at high RNFL thickness values and then a sharp decrease at lower RNFL thickness values. A broken stick statistical analysis was utilized to estimate the tipping point at which RNFL thickness values are associated with VF defects. The slope for the association between structure and function was computed for data above and below the tipping point. Results The mean RNFL thickness value that was associated with initial VF loss was 89 μm. The superior RNFL thickness value that was associated with initial corresponding inferior VF loss was 100 μm. The inferior RNFL thickness value that was associated with initial corresponding superior VF loss was 73 μm. The differences between all the slopes above and below the aforementioned tipping points were statistically significant (p<0.001). Conclusions In open angle glaucoma, substantial RNFL thinning or structural loss appears to be necessary before functional visual field defects become detectable. PMID:24487047

Evaluation of two-dimensional Bruch's membrane opening minimum rim area for glaucoma diagnostics in a large patient cohort.

PubMed

Enders, Philip; Adler, Werner; Kiessling, David; Weber, Vincent; Schaub, Friederike; Hermann, Manuel M; Dietlein, Thomas; Cursiefen, Claus; Heindl, Ludwig M

2018-03-24

To characterize the two-dimensional parameter Bruch's membrane opening minimum rim area (BMO-MRA) in spectral domain optical coherence tomography (SD-OCT) of the optic nerve head (ONH) compared to minimum rim width (BMO-MRW) and retinal nerve fibre layer (RNFL) thickness in a large patient cohort. Case-control, cross-sectional study of 705 eyes of 445 participants. A total of 449 eyes with glaucoma, 67 eyes with ocular hypertension and 189 healthy controls, underwent SD-OCT and confocal laser scanning tomography (CSLT), visual field testing and clinical examination. Morphometric ONH parameters, visual field function and diagnostic power were compared. Main outcome measures were SD-OCT-derived BMO-MRA, BMO-MRW, RNFL thickness and CSLT-derived rim area (DM-RA). Mean ONH area was 2.11 ± 0.57 mm 2 ; mean BMO area was 1.89 ± 0.45 mm 2 . Correlation of mean deviation in visual field to morphometric parameters was ρ = 0.70, (p < 0.001) for RNFL thickness, ρ = 0.68 (p < 0.001) for BMO-MRA, ρ = 0.66 (p < 0.001) for BMO-MRW. These correlations were not significantly different (p > 0.05), while DM-RA correlated significantly worse (ρ = 0.55; p < 0.001). In receiver operating characteristics, the calculated area under the curve (AUC) and sensitivity at 90% specificity to differentiate glaucoma were 0.87% and 70.1% for BMO-MRA, 0.86% and 68.1% for RNFL thickness, 0.84% and 66.0% for BMO-MRW, 0.82% and 51.3% for DM-RA. In a heterogenous clinical cohort of glaucoma patients, all analysed SD-OCT parameters excel DM-RA of CSLT. The two-dimensional parameter BMO-MRA shows comparable levels of diagnostic power to detect glaucoma compared to established parameters BMO-MRW and RNFL thickness. Given higher comparability between ONH sizes, BMO-MRA might become an additional standard tool in SD-OCT imaging for glaucoma. © 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Glaucoma Diagnostic Capability of Global and Regional Measurements of Isolated Ganglion Cell Layer and Inner Plexiform Layer.

PubMed

Chien, Jason L; Ghassibi, Mark P; Patthanathamrongkasem, Thipnapa; Abumasmah, Ramiz; Rosman, Michael S; Skaat, Alon; Tello, Celso; Liebmann, Jeffrey M; Ritch, Robert; Park, Sung Chul

2017-03-01

To compare glaucoma diagnostic capability of global/regional macular layer parameters in different-sized grids. Serial horizontal spectral-domain optical coherence tomography scans of macula were obtained. Automated macular grids with diameters of 3, 3.45, and 6 mm were used. For each grid, 10 parameters (total volume; average thicknesses in 9 regions) were obtained for 5 layers: macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), ganglion cell-inner plexiform layer (GCIPL; GCL+IPL), and ganglion cell complex (GCC; mRNFL+GCL+IPL). Sixty-nine normal eyes (69 subjects) and 87 glaucomatous eyes (87 patients) were included. For the total volume parameter, the area under the receiver operating characteristic curves (AUCs) in 6-mm grid were larger than the AUCs in 3- and 3.45-mm grids for GCL, GCC, GCIPL, and mRNFL (all P<0.020). For the average thickness parameters, the best AUC in 6-mm grid (T2 region for GCL, IPL, and GCIPL; I2 region for mRNFL and GCC) was greater than the best AUC in 3-mm grid for GCL, GCC, and mRNFL (P<0.045). The AUC of GCL volume (0.920) was similar to those of GCC (0.920) and GCIPL (0.909) volume. The AUC of GCL T2 region thickness (0.942) was similar to those of GCC I2 region (0.942) and GCIPL T2 region (0.934) thickness. Isolated macular GCL appears to be as good as GCC and GCIPL in glaucoma diagnosis, while IPL does not. Larger macular grids may be better at detecting glaucoma. Each layer has a characteristic region with the best glaucoma diagnostic capability.

Thickness related textural properties of retinal nerve fiber layer in color fundus images.

PubMed

Odstrcilik, Jan; Kolar, Radim; Tornow, Ralf-Peter; Jan, Jiri; Budai, Attila; Mayer, Markus; Vodakova, Martina; Laemmer, Robert; Lamos, Martin; Kuna, Zdenek; Gazarek, Jiri; Kubena, Tomas; Cernosek, Pavel; Ronzhina, Marina

2014-09-01

Images of ocular fundus are routinely utilized in ophthalmology. Since an examination using fundus camera is relatively fast and cheap procedure, it can be used as a proper diagnostic tool for screening of retinal diseases such as the glaucoma. One of the glaucoma symptoms is progressive atrophy of the retinal nerve fiber layer (RNFL) resulting in variations of the RNFL thickness. Here, we introduce a novel approach to capture these variations using computer-aided analysis of the RNFL textural appearance in standard and easily available color fundus images. The proposed method uses the features based on Gaussian Markov random fields and local binary patterns, together with various regression models for prediction of the RNFL thickness. The approach allows description of the changes in RNFL texture, directly reflecting variations in the RNFL thickness. Evaluation of the method is carried out on 16 normal ("healthy") and 8 glaucomatous eyes. We achieved significant correlation (normals: ρ=0.72±0.14; p≪0.05, glaucomatous: ρ=0.58±0.10; p≪0.05) between values of the model predicted output and the RNFL thickness measured by optical coherence tomography, which is currently regarded as a standard glaucoma assessment device. The evaluation thus revealed good applicability of the proposed approach to measure possible RNFL thinning. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Influences of the inner retinal sublayers and analytical areas in macular scans by spectral-domain OCT on the diagnostic ability of early glaucoma.

PubMed

Nakatani, Yusuke; Higashide, Tomomi; Ohkubo, Shinji; Sugiyama, Kazuhisa

2014-10-23

We investigated the influences of the inner retinal sublayers and analytical areas in macular scans by spectral-domain optical coherence tomography (OCT) on the diagnostic ability of early glaucoma. A total of 64 early (including 24 preperimetric) glaucomatous and 40 normal eyes underwent macular and peripapillary retinal nerve fiber layer (pRNFL) scans (3D-OCT-2000). The area under the receiver operating characteristics (AUC) for glaucoma diagnosis was determined from the average thickness of the total 100 grids (6 × 6 mm), central 44 grids (3.6 × 4.8 mm), and peripheral 56 grids (outside of the 44 grids), and for each macular sublayer: macular RNFL (mRNFL), ganglion cell layer plus inner plexiform layer (GCL/IPL), and mRNFL plus GCL/IPL (ganglion cell complex [GCC]). Correlation of OCT parameters with visual field parameters was evaluated by Spearman's rank correlation coefficients (rs). The GCC-related parameters had a significantly larger AUC (0.82-0.97) than GCL/IPL (0.81-0.91), mRNFL-related parameters (0.72-0.94), or average pRNFL (0.88) in more than half of all comparisons. The central 44 grids had a significantly lower AUC than other analytical areas in GCC and mRNFL thickness. Conversely, the peripheral 56 grids had a significantly lower AUC than the 100 grids in GCL/IPL inferior thickness. Inferior thickness of GCC (rs, 0.45-0.49) and mRNFL (rs, 0.43-0.51) showed comparably high correlations with central visual field parameters to average pRNFL thickness (rs, 0.41, 0.47) even in the central 44 grids. The diagnostic ability of macular OCT parameters for early glaucoma differed by inner retinal sublayers and also by the analytical areas studied. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Risk of Visual Field Progression in Glaucoma Patients with Progressive Retinal Nerve Fiber Layer Thinning: A 5-Year Prospective Study.

PubMed

Yu, Marco; Lin, Chen; Weinreb, Robert N; Lai, Gilda; Chiu, Vivian; Leung, Christopher Kai-Shun

2016-06-01

To investigate whether progressive retinal nerve fiber layer (RNFL) thinning is predictive of progressive visual field (VF) loss in glaucoma. Prospective study. A total of 139 primary open-angle glaucoma patients (240 eyes) followed up for ≥5 years. Retinal nerve fiber layer imaging and VF testing were performed at ∼4-month intervals. Progressive RNFL thinning was determined by event analysis (Guided Progression Analysis [GPA]) and trend analysis (Trend-based Progression Analysis [TPA]) of serial registered RNFL thickness maps. VF progression was detected according to the Early Manifest Glaucoma Trial (EMGT) ("likely progression") and pointwise linear regression (PLR) criteria (≥3 contiguous locations with sensitivity change <0 decibels [dB]/year at P < 0.01). Hazard ratios (HRs) for predicting VF progression were calculated by Cox proportional hazard modeling with progressive RNFL thinning as a time-dependent covariate. The specificity of GPA/TPA for detection of RNFL changes was determined by the proportion of eyes with significant RNFL thinning/thickening in 25 normal subjects followed weekly for 8 consecutive weeks and the proportion with significant RNFL thickening in the glaucoma group. The HRs of VF progression. A total of 65 (27.1%) and 117 eyes (48.8%) had progressive RNFL thinning based on GPA and TPA, respectively, and 30 (12.5%) and 39 eyes (16.3%) had VF progression per the EMGT and PLR criteria, respectively, during follow-up. Eyes with progressive RNFL thinning had lower VF survival estimates and a faster decline of visual field index than eyes without. Progressive RNFL thinning predicted the development of VF progression with HRs of 8.44 (95% confidence interval, 3.30-21.61) (EMGT criteria) and 5.11 (2.51-10.42) (PLR criteria) for TPA and 3.95 (1.74-8.93) (EMGT criteria) and 3.81 (1.83-7.92) (PLR criteria) for GPA after controlling for baseline covariates. The specificities of GPA and TPA were 100% (83.4%-100.0%) in the normal group and 81.7% (76.2%-86.4%) and 84.2% (78.9%-88.6%), respectively, in the glaucoma group. Progressive RNFL thinning determined by GPA and TPA is predictive of detectable functional decline in glaucoma. This finding underscores the significance of detecting progressive RNFL thinning and its relevance to initiate or augment treatment for glaucoma patients. Regulatory authorities may consider progressive RNFL thinning as an outcome measure in clinical trials for evaluation of glaucoma treatment. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Retinal Nerve Fiber Layer Thickness in Children With ADHD.

PubMed

Hergüner, Arzu; Alpfidan, İsmail; Yar, Ahmet; Erdoğan, Erkan; Metin, Özge; Sakarya, Yaşar; Hergüner, Sabri

2018-05-01

The current study aims to compare retinal nerve fiber layer (RNFL) thickness, macular thickness, and macular volume between children with ADHD and a control group. The study group included children with ADHD and the control group consisted of age- and gender-matched participants without any psychiatric disorder. In all participants, RNFL thickness, macular thickness, and macular volume were measured by using spectral domain-optical coherence tomography (SD-OCT). ADHD symptom severity was evaluated by using parent-report measures, including Conners' Parent Rating Scale-Revised: Short Form (CPRS-R: S) and the Strengths and Difficulties Questionnaire: Parent Form (SDQ: P). We compared 90 eyes of 45 children with ADHD and 90 eyes of 45 controls. ADHD group had significantly lower RNFL thickness only in nasal quadrant than the controls. The remaining RNFL quadrants, macular thickness, and volume were not significantly different between groups. There was a reverse correlation between RNFL thickness and ADHD symptom severity. This is the first study examining the RNFL thickness in ADHD. Our findings showed that nasal RNFL thickness was lower, indicating reduced unmyelinated axons in the retina of children with ADHD. The results of this study support the evidence that ADHD involves a lag in cortical maturation and this is measurable in the retina.

Evaluation of Macular Ganglion Cell Complex and Peripapillary Retinal Nerve Fiber Layer in Primary Craniopharyngioma by Fourier-Domain Optical Coherence Tomography.

PubMed

Yang, Liu; Qu, Yuanzhen; Lu, Wen; Liu, Fengjun

2016-07-03

BACKGROUND The aim of this study was to compare the differences in macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) in child and adult patients with primary craniopharyngioma by Fourier-domain optical coherence tomography (FD-OCT) and to evaluate their significance in the diagnosis of primary craniopharyngioma. MATERIAL AND METHODS Ninety-six participants were divided into 3 groups: 32 in the child craniopharyngioma group (CCG) and 32 in the adult craniopharyngioma group (ACG) who were treated in Beijing Tiantan Hospital between November 2013 and October 2014, and 32 in the normal group (NG). All subjects were scanned by FD-OCT to map GCC and pRNFL thicknesses. Spearman correlation coefficient was used to assess the correlation between GCC and pRNFL thickness, and pRNFL thickness and optic nerve head (ONH) parameters, including horizontal cup-disc ratio (HCDR), vertical cup-disc ratio (VCDR), optic disc area (ODA), and cup area (CA), respectively. RESULTS The correlation between GCC and pRNFL thickness in the CCG was slightly stronger compared with the ACG. A significant difference in GCC thickness was observed among the CCG, ACG, and NG. Although the pRNFL thickness in both the CCG and ACG was significantly higher than that in NG, no significant difference in pRNFL thickness was detected between the 2 craniopharyngioma groups. The average, superior, and inferior pRNFL thicknesses were negatively correlated with VCDR in the CCG (in double eyes) and ACG (only in left eyes). CONCLUSIONS GCC was more sensitive than pRNFL in detecting optic nerve damage in the eyes of craniopharyngioma patients. A thinner pRNFL was especially correlated with VCDR in child craniopharyngioma patients.

Evaluation of Macular Ganglion Cell Complex and Peripapillary Retinal Nerve Fiber Layer in Primary Craniopharyngioma by Fourier-Domain Optical Coherence Tomography

PubMed Central

Yang, Liu; Qu, Yuanzhen; Lu, Wen; Liu, Fengjun

2016-01-01

Background The aim of this study was to compare the differences in macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) in child and adult patients with primary craniopharyngioma by Fourier-domain optical coherence tomography (FD-OCT) and to evaluate their significance in the diagnosis of primary craniopharyngioma. Material/Methods Ninety-six participants were divided into 3 groups: 32 in the child craniopharyngioma group (CCG) and 32 in the adult craniopharyngioma group (ACG) who were treated in Beijing Tiantan Hospital between November 2013 and October 2014, and 32 in the normal group (NG). All subjects were scanned by FD-OCT to map GCC and pRNFL thicknesses. Spearman correlation coefficient was used to assess the correlation between GCC and pRNFL thickness, and pRNFL thickness and optic nerve head (ONH) parameters, including horizontal cup-disc ratio (HCDR), vertical cup-disc ratio (VCDR), optic disc area (ODA), and cup area (CA), respectively. Results The correlation between GCC and pRNFL thickness in the CCG was slightly stronger compared with the ACG. A significant difference in GCC thickness was observed among the CCG, ACG, and NG. Although the pRNFL thickness in both the CCG and ACG was significantly higher than that in NG, no significant difference in pRNFL thickness was detected between the 2 craniopharyngioma groups. The average, superior, and inferior pRNFL thicknesses were negatively correlated with VCDR in the CCG (in double eyes) and ACG (only in left eyes). Conclusions GCC was more sensitive than pRNFL in detecting optic nerve damage in the eyes of craniopharyngioma patients. A thinner pRNFL was especially correlated with VCDR in child craniopharyngioma patients. PMID:27372909

Does Optic Nerve Head Size Variation Affect Circumpapillary Retinal Nerve Fiber Layer Thickness Measurement by Optical Coherence Tomography?

PubMed Central

Huang, David; Chopra, Vikas; Lu, Ake Tzu-Hui; Tan, Ou; Francis, Brian; Varma, Rohit

2012-01-01

Purpose. To determine the relationship between retinal nerve fiber layer (RNFL) thickness, optic disc size, and image magnification. Methods. The cohort consisted of 196 normal eyes of 101 participants in the Advanced Imaging for Glaucoma Study (AIGS), a multicenter, prospective, longitudinal study to develop advanced imaging technologies for glaucoma diagnosis. Scanning laser tomography was used to measure disc size. Optical coherence tomography (OCT) was used to perform circumpapillary RNFL thickness measurements using the standard fixed 3.46-mm nominal scan diameter. A theoretical model of magnification effects was developed to relate RNFL thickness (overall average) with axial length and magnification. Results. Multivariate regression showed no significant correlation between RNFL thickness and optic disc area (95% confidence interval [CI] = −0.9 to 4.1 μm/mm2, P = 0.21). Linear regression showed that RNFL thickness depended significantly on axial length (slope = −3.1 μm/mm, 95% CI = −4.9 to −1.3, P = 0.001) and age (slope = −0.3 μm/y, 95% CI = −0.5 to −0.2, P = 0.0002). The slope values agreed closely with the values predicted by the magnification model. Conclusions. There is no significant association between RNFL thickness and optic disc area. Previous publications that showed such an association may have been biased by the effect of axial length on fundus image magnification and, therefore, both measured RNFL thickness and apparent disc area. The true diameter of the circumpapillary OCT scan is larger for a longer eye (more myopic eye), leading to a thinner RNFL measurement. Adjustment of measured RNFL thickness by axial length, in addition to age, may lead to a tighter normative range and improve the detection of RNFL thinning due to glaucoma. PMID:22743319

Influence of optic disc size on the diagnostic performance of macular ganglion cell complex and peripapillary retinal nerve fiber layer analyses in glaucoma.

PubMed

Cordeiro, Daniela Valença; Lima, Verônica Castro; Castro, Dinorah P; Castro, Leonardo C; Pacheco, Maria Angélica; Lee, Jae Min; Dimantas, Marcelo I; Prata, Tiago Santos

2011-01-01

To evaluate the influence of optic disc size on the diagnostic accuracy of macular ganglion cell complex (GCC) and conventional peripapillary retinal nerve fiber layer (pRNFL) analyses provided by spectral domain optical coherence tomography (SD-OCT) in glaucoma. Eighty-two glaucoma patients and 30 healthy subjects were included. All patients underwent GCC (7 × 7 mm macular grid, consisting of RNFL, ganglion cell and inner plexiform layers) and pRNFL thickness measurement (3.45 mm circular scan) by SD-OCT. One eye was randomly selected for analysis. Initially, receiver operating characteristic (ROC) curves were generated for different GCC and pRNFL parameters. The effect of disc area on the diagnostic accuracy of these parameters was evaluated using a logistic ROC regression model. Subsequently, 1.5, 2.0, and 2.5 mm(2) disc sizes were arbitrarily chosen (based on data distribution) and the predicted areas under the ROC curves (AUCs) and sensitivities were compared at fixed specificities for each. Average mean deviation index for glaucomatous eyes was -5.3 ± 5.2 dB. Similar AUCs were found for the best pRNFL (average thickness = 0.872) and GCC parameters (average thickness = 0.824; P = 0.19). The coefficient representing disc area in the ROC regression model was not statistically significant for average pRNFL thickness (-0.176) or average GCC thickness (0.088; P ≥ 0.56). AUCs for fixed disc areas (1.5, 2.0, and 2.5 mm(2)) were 0.904, 0.891, and 0.875 for average pRNFL thickness and 0.834, 0.842, and 0.851 for average GCC thickness, respectively. The highest sensitivities - at 80% specificity for average pRNFL (84.5%) and GCC thicknesses (74.5%) - were found with disc sizes fixed at 1.5 mm(2) and 2.5 mm(2). Diagnostic accuracy was similar between pRNFL and GCC thickness parameters. Although not statistically significant, there was a trend for a better diagnostic accuracy of pRNFL thickness measurement in cases of smaller discs. For GCC analysis, an inverse effect was observed.

Retinal tissue thickness in type 1 and type 2 diabetes.

PubMed

Srinivasan, Sangeetha; Pritchard, Nicola; Sampson, Geoff P; Edwards, Katie; Vagenas, Dimitrios; Russell, Anthony W; Malik, Rayaz A; Efron, Nathan

2016-01-01

The objective was to investigate full retinal and inner retinal thickness in individuals with type 1 and type 2 diabetes. Eighty-four individuals with type 1 diabetes (T1DM), 67 individuals with type 2 diabetes (T2DM) and 42 non-diabetic individuals (control group) were enrolled. Participants underwent full retinal thickness evaluation in the central retinal, parafoveal and perifoveal zones and in the retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC), using spectral domain optical coherence tomography. As a preliminary step, the key variables of interest - age, sex, diabetic retinopathy (DR), duration of diabetes and HbA1c levels - were analysed and compared between the three groups. Full retinal thickness, RNFL and GCC thicknesses were also compared between the groups. The relationship between the type of diabetes and retinal tissue thickness was explored, adjusting for the five potential confounders. Compared to individuals with T1DM, individuals with T2DM had significantly reduced full retinal thickness in the parafovea and perifovea and reduced RNFL and GCC thickness. The mean differences were six (p = 0.020), seven (p = 0.008), six (p = 0.021) and four micrometres (p = 0.013) for the parafovea, perifovea, RNFL and GCC thicknesses, respectively. Thicknesses within the central zone (p = 0.018) and at the parafovea (p = 0.007) were significantly reduced in T2DM when compared to the control group. After adjusting for age, sex, diabetic retinopathy, duration of diabetes and HbA1c levels, the relationship between type of diabetes and retinal tissue thickness was not statistically significant (p > 0.056). Retinal tissue thickness is not significantly different between type 1 and type 2 diabetes, when adjusted for age, sex, diabetic retinopathy, duration of diabetes and HbA1c levels. © 2016 Optometry Australia.

Optical Coherence Tomography in Glaucoma

NASA Astrophysics Data System (ADS)

Berisha, Fatmire; Hoffmann, Esther M.; Pfeiffer, Norbert

Retinal nerve fiber layer (RNFL) thinning and optic nerve head cupping are key diagnostic features of glaucomatous optic neuropathy. The higher resolution of the recently introduced SD-OCT offers enhanced visualization and improved segmentation of the retinal layers, providing a higher accuracy in identification of subtle changes of the optic disc and RNFL thinning associated with glaucoma.

Characteristics of peripapillary retinal nerve fiber layer in preterm children.

PubMed

Wang, Jingyun; Spencer, Rand; Leffler, Joel N; Birch, Eileen E

2012-05-01

To examine quantitatively characteristics of the peripapillary retinal nerve fiber layer (RNFL) in preterm children using Fourier-domain optical coherence tomography (FD-OCT). Prospective cross-sectional study. A 3-mm high-resolution FD-OCT peripapillary RNFL circular scan centered on the optic disc was obtained from right eyes of 25 preterm children (10.6 ± 3.7 years old, 8 preterm and 17 with regressed retinopathy of prematurity with normal-appearing posterior poles) and 54 full-term controls (9.8 ± 3.2 years old). Images were analyzed using Spectralis FD-OCT software to obtain average thickness measurements for 6 sectors (temporal superior, temporal, temporal inferior, nasal inferior, nasal, nasal superior), and the global average. The RNFL global average for preterm children was 8% thinner than for full-term controls. In the preterm group, peripapillary RNFL thickness on the temporal side of the disc was 6% thicker than in full-term controls, while all other peripapillary RNFL sectors were 9% to 13% thinner. In the preterm group, temporal sector peripapillary RNFL thickness was correlated with gestational age (r = -0.47, P < .001), with foveal center total thickness (r = 0.48, P = .008, 1-tailed), and with visual acuity (r = 0.42; P = .026, 1-tailed). The significantly thinner RNFL global average for preterm children suggests that prematurity is associated with subclinical optic nerve hypoplasia. Significant correlations between temporal sector RNFL thickness and both the foveal thickness and visual acuity suggest that the peripapillary RNFL is related to abnormalities in macular development as a result of preterm birth. Copyright © 2012 Elsevier Inc. All rights reserved.

Retinal layer segmentation in multiple sclerosis: a systematic review and meta-analysis.

PubMed

Petzold, Axel; Balcer, Laura J; Calabresi, Peter A; Costello, Fiona; Frohman, Teresa C; Frohman, Elliot M; Martinez-Lapiscina, Elena H; Green, Ari J; Kardon, Randy; Outteryck, Olivier; Paul, Friedemann; Schippling, Sven; Vermersch, Patrik; Villoslada, Pablo; Balk, Lisanne J

2017-10-01

Structural retinal imaging biomarkers are important for early recognition and monitoring of inflammation and neurodegeneration in multiple sclerosis. With the introduction of spectral domain optical coherence tomography (SD-OCT), supervised automated segmentation of individual retinal layers is possible. We aimed to investigate which retinal layers show atrophy associated with neurodegeneration in multiple sclerosis when measured with SD-OCT. In this systematic review and meta-analysis, we searched for studies in which SD-OCT was used to look at the retina in people with multiple sclerosis with or without optic neuritis in PubMed, Web of Science, and Google Scholar between Nov 22, 1991, and April 19, 2016. Data were taken from cross-sectional cohorts and from one timepoint from longitudinal studies (at least 3 months after onset in studies of optic neuritis). We classified data on eyes into healthy controls, multiple-sclerosis-associated optic neuritis (MSON), and multiple sclerosis without optic neuritis (MSNON). We assessed thickness of the retinal layers and we rated individual layer segmentation performance by random effects meta-analysis for MSON eyes versus control eyes, MSNON eyes versus control eyes, and MSNON eyes versus MSON eyes. We excluded relevant sources of bias by funnel plots. Of 25 497 records identified, 110 articles were eligible and 40 reported data (in total 5776 eyes from patients with multiple sclerosis [1667 MSON eyes and 4109 MSNON eyes] and 1697 eyes from healthy controls) that met published OCT quality control criteria and were suitable for meta-analysis. Compared with control eyes, the peripapillary retinal nerve fibre layer (RNFL) showed thinning in MSON eyes (mean difference -20·10 μm, 95% CI -22·76 to -17·44; p<0·0001) and in MSNON eyes (-7·41 μm, -8·98 to -5·83; p<0·0001). The macula showed RNFL thinning of -6·18 μm (-8·07 to -4·28; p<0·0001) in MSON eyes and -2·15 μm (-3·15 to -1·15; p<0·0001) in MSNON eyes compared with control eyes. Atrophy of the macular ganglion cell layer and inner plexiform layer (GCIPL) was -16·42 μm (-19·23 to -13·60; p<0·0001) for MSON eyes and -6·31 μm (-7·75 to -4·87; p<0·0001) for MSNON eyes compared with control eyes. A small degree of inner nuclear layer (INL) thickening occurred in MSON eyes compared with control eyes (0·77 μm, 0·25 to 1·28; p=0·003). We found no statistical difference in the thickness of the combined outer nuclear layer and outer plexiform layer when we compared MSNON or MSON eyes with control eyes, but we found a small degree of thickening of the combined layer when we compared MSON eyes with MSNON eyes (1·21 μm, 0·24 to 2·19; p=0·01). The largest and most robust differences between the eyes of people with multiple sclerosis and control eyes were found in the peripapillary RNFL and macular GCIPL. Inflammatory disease activity might be captured by the INL. Because of the consistency, robustness, and large effect size, we recommend inclusion of the peripapillary RNFL and macular GCIPL for diagnosis, monitoring, and research. None. Copyright © 2017 Elsevier Ltd. All rights reserved.

Segmented inner plexiform layer thickness as a potential biomarker to evaluate open-angle glaucoma: Dendritic degeneration of retinal ganglion cell.

PubMed

Kim, Eun Kyoung; Park, Hae-Young Lopilly; Park, Chan Kee

2017-01-01

To evaluate the changes of retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), and ganglion cell-inner plexiform layer (GCIPL) thicknesses and compare structure-function relationships of 4 retinal layers using spectral-domain optical coherence tomography (SD-OCT) in macular region of glaucoma patients. In cross-sectional study, a total of 85 eyes with pre-perimetric to advanced glaucoma and 26 normal controls were enrolled. The glaucomatous eyes were subdivided into three groups according to the severity of visual field defect: a preperimetric glaucoma group, an early glaucoma group, and a moderate to advanced glaucoma group. RNFL, GCL, IPL, and GCIPL thicknesses were measured at the level of the macula by the Spectralis (Heidelberg Engineering, Heidelberg, Germany) SD-OCT with automated segmentation software. For functional evaluation, corresponding mean sensitivity (MS) values were measured using 24-2 standard automated perimetry (SAP). RNFL, GCL, IPL, and GCIPL thicknesses were significantly different among 4 groups (P < .001). Macular structure losses were positively correlated with the MS values of the 24-2 SAP for RNFL, GCL, IPL, and GCIPL (R = 0.553, 0.636, 0.648 and 0.646, respectively, P < .001). In regression analysis, IPL and GCIPL thicknesses showed stronger association with the corresponding MS values of 24-2 SAP compared with RNFL and GCL thicknesses (R2 = 0.420, P < .001 for IPL; R2 = 0.417, P< .001 for GCIPL thickness). Segmented IPL thickness was significantly associated with the degree of glaucoma. Segmental analysis of the inner retinal layer including the IPL in macular region may provide valuable information for evaluating glaucoma.

Quantitative RNFL attenuation coefficient measurements by RPE-normalized OCT data

NASA Astrophysics Data System (ADS)

Vermeer, K. A.; van der Schoot, J.; Lemij, H. G.; de Boer, J. F.

2012-03-01

We demonstrate significantly different scattering coefficients of the retinal nerve fiber layer (RNFL) between normal and glaucoma subjects. In clinical care, SD-OCT is routinely used to assess the RNFL thickness for glaucoma management. In this way, the full OCT data set is conveniently reduced to an easy to interpret output, matching results from older (non- OCT) instruments. However, OCT provides more data, such as the signal strength itself, which is due to backscattering in the retinal layers. For quantitative analysis, this signal should be normalized to adjust for local differences in the intensity of the beam that reaches the retina. In this paper, we introduce a model that relates the OCT signal to the attenuation coefficient of the tissue. The average RNFL signal (within an A-line) was then normalized based on the observed RPE signal, resulting in normalized RNFL attenuation coefficient maps. These maps showed local defects matching those found in thickness data. The average (normalized) RNFL attenuation coefficient of a fixed band around the optic nerve head was significantly lower in glaucomatous eyes than in normal eyes (3.0mm-1 vs. 4.9mm-1, P<0.01, Mann-Whitney test).

Analysis of Visual Appearance of Retinal Nerve Fibers in High Resolution Fundus Images: A Study on Normal Subjects

PubMed Central

Tornow, Ralf P.; Odstrcilik, Jan; Mayer, Markus A.; Gazarek, Jiri; Jan, Jiri; Kubena, Tomas; Cernosek, Pavel

2013-01-01

The retinal ganglion axons are an important part of the visual system, which can be directly observed by fundus camera. The layer they form together inside the retina is the retinal nerve fiber layer (RNFL). This paper describes results of a texture RNFL analysis in color fundus photographs and compares these results with quantitative measurement of RNFL thickness obtained from optical coherence tomography on normal subjects. It is shown that local mean value, standard deviation, and Shannon entropy extracted from the green and blue channel of fundus images are correlated with corresponding RNFL thickness. The linear correlation coefficients achieved values 0.694, 0.547, and 0.512 for respective features measured on 439 retinal positions in the peripapillary area from 23 eyes of 15 different normal subjects. PMID:24454526

Analysis of visual appearance of retinal nerve fibers in high resolution fundus images: a study on normal subjects.

PubMed

Kolar, Radim; Tornow, Ralf P; Laemmer, Robert; Odstrcilik, Jan; Mayer, Markus A; Gazarek, Jiri; Jan, Jiri; Kubena, Tomas; Cernosek, Pavel

2013-01-01

The retinal ganglion axons are an important part of the visual system, which can be directly observed by fundus camera. The layer they form together inside the retina is the retinal nerve fiber layer (RNFL). This paper describes results of a texture RNFL analysis in color fundus photographs and compares these results with quantitative measurement of RNFL thickness obtained from optical coherence tomography on normal subjects. It is shown that local mean value, standard deviation, and Shannon entropy extracted from the green and blue channel of fundus images are correlated with corresponding RNFL thickness. The linear correlation coefficients achieved values 0.694, 0.547, and 0.512 for respective features measured on 439 retinal positions in the peripapillary area from 23 eyes of 15 different normal subjects.

Changes in Retinal Nerve Fiber Layer Thickness after Multiple Injections of Novel VEGF Decoy Receptor Conbercept for Various Retinal Diseases.

PubMed

Zhang, Zhihua; Yang, Xiaolu; Jin, Huiyi; Qu, Yuan; Zhang, Yuan; Liu, Kun; Xu, Xun

2016-12-06

Conbercept is a recombinant fusion protein with high affinity for all vascular endothelial growth factor isoforms and placental growth factor. The repeated intravitreal injection of conbercept may cause intraocular pressure (IOP) fluctuations and long-term suppression of neurotrophic cytokines, which could lead to retinal nerve fiber layer (RNFL) damage. This retrospective fellow-eye controlled study included 98 eyes of 49 patients. The changes in IOP and RNFL thickness as well as the correlation between RNFL changes and associated factors were evaluated. The IOP value between the baseline and the last follow-up visit in the injection group and the IOP value of the last follow-up visit between the injection and non-injection groups were not significantly different (p = 0.452 and 0.476, respectively). The global average thickness of the RNFL (μm) in the injection group decreased from 108.9 to 106.1; however, the change was not statistically significant (p = 0.118). No significant difference in the average RNFL thickness was observed at the last follow-up visit between the injection and non-injection groups (p = 0.821). The type of disease was the only factor associated with RNFL thickness changes. In conclusion, repeated intravitreal injections with 0.05 mL conbercept revealed an excellent safety profile for RNFL thickness, although short-term IOP changes were observed.

Changes in optical coherence tomography measurements after orbital wall decompression in dysthyroid optic neuropathy.

PubMed

Park, Kyung-Ah; Kim, Yoon-Duck; Woo, Kyung In

2018-06-01

The purpose of our study was to assess changes in peripapillary retinal nerve fiber layer (RNFL) thickness after orbital wall decompression in eyes with dysthyroid optic neuropathy (DON). We analyzed peripapillary optical coherence tomography (OCT) images (Cirrus HD-OCT) from controls and patients with DON before and 1 and 6 months after orbital wall decompression. There was no significant difference in mean preoperative peripapillary retinal nerve fiber layer thickness between eyes with DON and controls. The superior and inferior peripapillary RNFL thickness decreased significantly 1 month after decompression surgery compared to preoperative values (p = 0.043 and p = 0.022, respectively). The global average, superior, temporal, and inferior peripapillary RNFL thickness decreased significantly 6 months after decompression surgery compared to preoperative values (p = 0.015, p = 0.028, p = 0.009, and p = 0.006, respectively). Patients with greater preoperative inferior peripapillary RNFL thickness tended to have better postoperative visual acuity at the last visit (p = 0.024, OR = 0.926). Our data revealed a significant decrease in peripapillary RNFL thickness postoperatively after orbital decompression surgery in patients with DON. We also found that greater preoperative inferior peripapillary RNFL thickness was associated with better visual outcomes. We suggest that RNFL thickness can be used as a prognostic factor for DON before decompression surgery.

Scanning Laser Polarimetry and Optical Coherence Tomography for Detection of Retinal Nerve Fiber Layer Defects

PubMed Central

Oh, Jong-Hyun

2009-01-01

Purpose To compare the ability of scanning laser polarimetry with variable corneal compensation (GDx-VCC) and Stratus optical coherence tomography (OCT) to detect photographic retinal nerve fiber layer (RNFL) defects. Methods This retrospective cross-sectional study included 45 eyes of 45 consecutive glaucoma patients with RNFL defects in red-free fundus photographs. The superior and inferior temporal quadrants in each eye were included for data analysis separately. The location and presence of RNFL defects seen in red-free fundus photographs were compared with those seen in GDx-VCC deviation maps and OCT RNFL analysis maps for each quadrant. Results Of the 90 quadrants (45 eyes), 31 (34%) had no apparent RNFL defects, 29 (32%) had focal RNFL defects, and 30 (33%) had diffuse RNFL defects in red-free fundus photographs. The highest agreement between GDx-VCC and red-free photography was 73% when we defined GDx-VCC RNFL defects as a cluster of three or more color-coded squares (p<5%) along the traveling line of the retinal nerve fiber in the GDx-VCC deviation map (kappa value, 0.388; 95% confidence interval (CI), 0.195 to 0.582). The highest agreement between OCT and red-free photography was 85% (kappa value, 0.666; 95% CI, 0.506 to 0.825) when a value of 5% outside the normal limit for the OCT analysis map was used as a cut-off value for OCT RNFL defects. Conclusions According to the kappa values, the agreement between GDx-VCC deviation maps and red-free photography was poor, whereas the agreement between OCT analysis maps and red-free photography was good. PMID:19794943

Evaluation of retinal nerve fiber layer thickness in vernal keratoconjunctivitis patients under long-term topical corticosteroid therapy.

PubMed

Cingu, Abdullah Kursat; Cinar, Yasin; Turkcu, Fatih Mehmet; Sahinoglu-Keskek, Nedime; Sahin, Alparslan; Sahin, Muhammed; Yuksel, Harun; Caca, Ihsan

2014-09-01

The aim of this study was to evaluate the retinal nerve fiber layer (RNFL) thickness in vernal keratoconjunctivitis (VKC) patients who were under long-term topical corticosteroid therapy. Thirty-six eyes of 36 VKC patients with clear cornea and normal videokeratography and 40 eyes of 40 age- and gender-matched normal children were included in the study. Clinical and demographic characteristics of the patients were noted and detailed ophthalmological examination was performed. Visual acuity (VA), spherical equivalent (SE), axial length (AL) and RNFL thickness measurements were compared between the groups. To correct ocular magnification effect on RNFL, we used Littmann's formula. All VKC patients had history of topical corticosteroid use and the mean duration of the topical corticosteroid use was 23.8 ± 9.09 months. There was no significant difference between the groups in terms of intraocular pressure (IOP). VKC group had significantly worse VA, greater SE and AL and thinner mean global, superior and inferior RNFL thickness. There were significant negative correlations between the duration of topical corticosteroid use and the mean global, superior and temporal RNFL thickness in VKC group. After correction of magnification effect, VKC group still had thinner mean global, superior and inferior RNFL thickness, and significant difference between the groups in inferior RNFL thickness did not disappear. Significant RNFL thickness difference between the groups suggests a possible effect of long-term corticosteroid use in VKC patients. Because visual field (VF) analysis in pediatric patients is difficult to perform and IOP may be illusive, RNFL thickness measurements in addition to routine examinations in VKC patients may help clinicians in their practice.

Analysis of the Retinal Nerve Fiber Layer Thickness in Alzheimer Disease and Mild Cognitive Impairment.

PubMed

Kwon, Jin Young; Yang, Ji Ho; Han, Ji Sang; Kim, Do Gyun

2017-12-01

To compare the retinal nerve fiber layer (RNFL) as well as the macula volume and thickness in the eyes of age-matched healthy controls with no cognitive disabilities with those of elderly people with mild cognitive impairment (MCI) or Alzheimer disease (AD). We used optical coherence tomography (OCT) to determine the effectiveness of the above quantities for early diagnosis of MCI or AD. Ninety eyes were considered in this study, split between 30 normal eyes, 30 eyes from patients with MCI, and 30eyes from patients with AD. All subjects underwent ophthalmologic and cognitive examinations, and measurements of the RNFL thickness as well as macular volume and thickness were taken for all patients using OCT. The mean RNFL thickness upon OCT was significantly thinner in the AD group than in the MCI group (p = 0.01). The RNFL was thinner in the superior quadrant in patients with AD when compared to the healthy controls (p = 0.03). The RNFL thicknesses in the inferior, nasal, and temporal quadrants did not differ significantly between the groups. Measurements in the 12 clock-hour zones revealed that zone 11 had a significantly thinner RNFL in the AD group as compared with the healthy control group (p = 0.02). In zone 2, the MCI group had a significantly thinner RNFL than the AD group (p = 0.03). Our OCT findings revealed a neuroanatomic difference in the RNFL thickness among the three groups, i.e., the AD, MCI, and healthy control groups. This suggests that a change in average RNFL thickness could be a meaningful index for diagnosing early AD. © 2017 The Korean Ophthalmological Society

Reduction in Retinal Nerve Fiber Layer Thickness in Young Adults with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Emberti Gialloreti, Leonardo; Pardini, Matteo; Benassi, Francesca; Marciano, Sara; Amore, Mario; Mutolo, Maria Giulia; Porfirio, Maria Cristina; Curatolo, Paolo

2014-01-01

Recent years have seen an increase in the use of retinal nerve fiber layer (RNFL) evaluation as an easy-to-use, reproducible, proxy-measure of brain structural abnormalities. Here, we evaluated RNFL thickness in a group of subjects with high functioning autism (HFA) or with Asperger Syndrome (AS) to its potential as a tool to study autism…

Clinical Use of an Optical Coherence Tomography Linear Discriminant Function for Differentiating Glaucoma From Normal Eyes.

PubMed

Choi, Yun Jeong; Jeoung, Jin Wook; Park, Ki Ho; Kim, Dong Myung

2016-03-01

To determine and validate the diagnostic ability of a linear discriminant function (LDF) based on retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness obtained using high-definition optical coherence tomography (Cirrus HD-OCT) for discriminating between healthy controls and early glaucoma subjects. We prospectively selected 214 healthy controls and 152 glaucoma subjects (teaching set) and another independent sample of 86 healthy controls and 71 glaucoma subjects (validating set). Two scans, including 1 macular and 1 peripapillary RNFL scan, were obtained. After calculating the LDF in the teaching set using the binary logistic regression analysis, receiver operating characteristic curves were plotted and compared between the OCT-provided parameters and LDF in the validating set. The proposed LDF was 16.529-(0.132×superior RNFL)-(0.064×inferior RNFL)+(0.039×12 o'clock RNFL)+(0.038×1 o'clock RNFL)+(0.084×superior GCIPL)-(0.144×minimum GCIPL). The highest area under the receiver operating characteristic (AUROC) curve was obtained for LDF in both sets (AUROC=0.95 and 0.96). In the validating set, the LDF showed significantly higher AUROC than the best RNFL (inferior RNFL=0.91) and GCIPL parameter (minimum GCIPL=0.88). The LDF yielded a sensitivity of 93.0% at a fixed specificity of 85.0%. The LDF showed better diagnostic ability for differentiating between healthy and early glaucoma subjects than individual OCT parameters. A classification algorithm based on the LDF can be used in the OCT analysis for glaucoma diagnosis.

An Assessment of Retinal Nerve Fiber Layer Thickness in Non-Diabetic Obese Children and Adolescents

PubMed Central

Özen, Bediz; Öztürk, Hakan; Çatlı, Gönül; Dündar, Bumin

2018-01-01

Objective: Obesity affects almost all systems in the body. This includes the retinal nerve fibers which may be damaged due to a chronic inflammatory process. To determine changes in retinal nerve fiber layer (RNFL) thickness in non-diabetic children and adolescents using optical coherence tomography (OCT) and to evaluate the relationship between this change, metabolic risk factors and pubertal stage. Methods: Thirty-eight obese and 40 healthy children and adolescents aged 10-18 years were included in the study. RNFL measurements from the optic disk and all surrounding quadrants were obtained using OCT from both eyes of the individuals in the study groups. Correlations between RNFL thickness and age, auxological measurements, pubertal stage, systolic and diastolic blood pressure, homeostasis model assessment-insulin resistance (HOMA-IR) index and lipid values were investigated. Results: A general decrease was observed in RNFL thickness in obese subjects compared to the controls, the decrease being highest in the inferior quadrant, although these differences were not statistically significant (p>0.05). RNFL thickness was negatively correlated with body mass index (BMI) standard deviation score (SDS) in both groups (control group r=-0.345, p=0.029; obese group r=-0.355, p=0.022). Significant negative correlations were determined between diastolic blood pressure, HOMA-IR, low density lipoprotein cholesterol level and RNFL thickness (r=-0.366, p=0.024; r=-0.394, p=0.016; and r=-0.374, p=0.022, respectively) in the obese group, while there was no association between these parameters and RNFL thickness in the control group. Conclusion: In this cross-sectional study, no statistically significant difference in RNFL thicknesses between the obese and control groups was determined. However, RNFL thickness was found to decrease in both healthy and obese children as BMI-SDS values increased. Further prospective studies may be of benefit to determine whether the decrease in RNFL values might become more pronounced on long-term follow-up. PMID:28739552

Evaluation of retinal nerve fiber layer thickness profile in thyroid ophthalmopathy without optic nerve dysfunction

PubMed Central

Mugdha, Kumari; Kaur, Apjit; Sinha, Neha; Saxena, Sandeep

2016-01-01

AIM To evaluate retinal nerve fiber layer (RNFL) thickness profile in patients of thyroid ophthalmopathy with no clinical signs of optic nerve dysfunction. METHODS A prospective, case-control, observational study conducted at a tertiary care centre. Inclusion criteria consisted of patients with eyelid retraction in association with any one of: biochemical thyroid dysfunction, exophthalmos, or extraocular muscle involvement; or thyroid dysfunction in association with either exophthalmos or extra-ocular muscle involvement; or a clinical activity score (CAS)>3/7. Two measurements of RNFL thickness were done for each eye, by Cirrus HD-optical coherence tomography 6mo apart. RESULTS Mean age of the sample was 38.75y (range 13-70y) with 18 males and 22 females. Average RNFL thickness at first visit was 92.06±12.44 µm, significantly lower than control group (101.28±6.64 µm) (P=0.0001). Thickness of inferior quadrant decreased from 118.2±21.27 µm to 115.0±22.27 µm after 6mo (P=0.02). There was no correlation between the change in CAS and RNFL thickness. CONCLUSION Decreased RNFL thickness is an important feature of thyroid orbitopathy, which is an inherent outcome of compressive optic neuropathy of any etiology. Subclinical RNFL damage continues in the absence of clinical activity of the disease. RNFL evaluation is essential in Grave's disease and active intervention may be warranted in the presence of significant damage. PMID:27990368

Retina ganglion cell/inner plexiform layer and peripapillary nerve fiber layer thickness in patients with acromegaly.

PubMed

Şahin, Muhammed; Şahin, Alparslan; Kılınç, Faruk; Yüksel, Harun; Özkurt, Zeynep Gürsel; Türkcü, Fatih Mehmet; Pekkolay, Zafer; Soylu, Hikmet; Çaça, İhsan

2017-06-01

Increased secretion of growth hormone and insulin-like growth factor-1 in acromegaly has various effects on multiple organs. However, the ocular effects of acromegaly have yet to be investigated in detail. The aim of the present study was to compare retina ganglion cell/inner plexiform layer (GCIPL) and peripapillary nerve fiber layer thickness (pRNFL) between patients with acromegaly and healthy control subjects using spectral domain optical coherence tomography (SD-OCT). This cross-sectional, comparative study included 18 patients with acromegaly and 20 control subjects. All participants underwent SD-OCT to measure pRNFL (in the seven peripapillary areas), GCIPL (in the nine ETDRS areas), and central macular thickness (CMT). Visual field (VF) examinations were performed using a Humphrey field analyzer in acromegalic patients. Measurements were compared between patients with acromegaly and control subjects. A total of 33 eyes of 18 patients with acromegaly and 40 eyes of 20 control subjects met the inclusion criteria of the present study. The overall calculated average pRNFL thickness was significantly lower in patients with acromegaly than in control subjects (P = 0.01), with pRNFL thickness significantly lower in the temporal superior and temporal inferior quadrants. Contrary to our expectations, pRNFL thickness in the nasal quadrant was similar between acromegalic and control subjects. The mean overall pRNFL thickness and superonasal, nasal, inferonasal, and inferotemporal quadrant pRNFL thicknesses were found to correlate with the mean deviation (MD) according to Spearman's correlation. However, other quadrants were not correlated with VF sensitivity. No significant difference in CMT values was observed (P = 0.6). GCIPL thickness was significantly lower in all quadrants of the inner and outer macula, except for central and inferior outer quadrants, in the acromegaly group than that in the control group (P < 0.05). GCIPL thicknesses of the inferior inner and outer macula quadrants were found to correlate with MD, whereas no correlation was observed between other quadrants and VF sensitivity. We demonstrated that GCIPL thickness decreased in patients with acromegaly compared with that in control subjects. However, the nasal quadrant pRNFL thickness was similar in acromegaly, in contrast to our expectations. SD-OCT may have utility in the assessment of the effects of acromegaly on retinal structures.

Glaucoma diagnostic ability of ganglion cell-inner plexiform layer thickness differs according to the location of visual field loss.

PubMed

Shin, Hye-Young; Park, Hae-Young Lopilly; Jung, Kyoung-In; Choi, Jin-A; Park, Chan Kee

2014-01-01

To determine whether the ganglion cell-inner plexiform layer (GCIPL) or circumpapillary retinal nerve fiber layer (cpRNFL) is better at distinguishing eyes with early glaucoma from normal eyes on the basis of the the initial location of the visual field (VF) damage. Retrospective, observational study. Eighty-four patients with early glaucoma and 43 normal subjects were enrolled. The patients with glaucoma were subdivided into 2 groups according to the location of VF damage: (1) an isolated parafoveal scotoma (PFS, N = 42) within 12 points of a central 10 degrees in 1 hemifield or (2) an isolated peripheral nasal step (PNS, N = 42) within the nasal periphery outside 10 degrees of fixation in 1 hemifield. All patients underwent macular and optic disc scanning using Cirrus high-definition optical coherence tomography (Carl Zeiss Meditec, Dublin, CA). The GCIPL and cpRNFL thicknesses were compared between groups. Areas under the receiver operating characteristic curves (AUCs) were calculated. Comparison of diagnostic ability using AUCs. The average and minimum GCIPL of the PFS group were significantly thinner than those of the PNS group, whereas there was no significant difference in the average retinal nerve fiber layer (RNFL) thickness between the 2 groups. The AUCs of the average (0.962) and minimum GCIPL (0.973) thicknesses did not differ from that of the average RNFL thickness (0.972) for discriminating glaucomatous changes between normal and all glaucoma eyes (P =0.566 and 0.974, respectively). In the PFS group, the AUCs of the average (0.988) and minimum GCIPL (0.999) thicknesses were greater than that of the average RNFL thickness (0.961, P =0.307 and 0.125, respectively). However, the AUCs of the average (0.936) and minimum GCIPL (0.947) thicknesses were lower than that of the average RNFL thickness (0.984) in the PNS group (P =0.032 and 0.069, respectively). The GCIPL parameters were more valuable than the cpRNFL parameters for detecting glaucoma in eyes with parafoveal VF loss, and the cpRNFL parameters were better than the GCIPL parameters for detecting glaucoma in eyes with peripheral VF loss. Clinicians should know that the diagnostic capability of macular GCIPL parameters depends largely on the location of the VF loss. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Optical Coherence Tomography Scan Circle Location and Mean Retinal Nerve Fiber Layer Measurement Variability

PubMed Central

Gabriele, Michelle L.; Ishikawa, Hiroshi; Wollstein, Gadi; Bilonick, Richard A.; Townsend, Kelly A.; Kagemann, Larry; Wojtkowski, Maciej; Srinivasan, Vivek J.; Fujimoto, James G.; Duker, Jay S.; Schuman, Joel S.

2009-01-01

PURPOSE To investigate the effect on optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness measurements of varying the standard 3.4-mm-diameter circle location. METHODS The optic nerve head (ONH) region of 17 eyes of 17 healthy subjects was imaged with high-speed, ultrahigh-resolution OCT (hsUHR-OCT; 501 × 180 axial scans covering a 6 × 6-mm area; scan time, 3.84 seconds) for a comprehensive sampling. This method allows for systematic simulation of the variable circle placement effect. RNFL thickness was measured on this three-dimensional dataset by using a custom-designed software program. RNFL thickness was resampled along a 3.4-mm-diameter circle centered on the ONH, then along 3.4-mm circles shifted horizontally (x-shift), vertically (y-shift) and diagonally up to ±500 µm (at 100-µm intervals). Linear mixed-effects models were used to determine RNFL thickness as a function of the scan circle shift. A model for the distance between the two thickest measurements along the RNFL thickness circular profile (peak distance) was also calculated. RESULTS RNFL thickness tended to decrease with both positive and negative x- and y-shifts. The range of shifts that caused a decrease greater than the variability inherent to the commercial device was greater in both nasal and temporal quadrants than in the superior and inferior ones. The model for peak distance demonstrated that as the scan moves nasally, the RNFL peak distance increases, and as the circle moves temporally, the distance decreases. Vertical shifts had a minimal effect on peak distance. CONCLUSIONS The location of the OCT scan circle affects RNFL thickness measurements. Accurate registration of OCT scans is essential for measurement reproducibility and longitudinal examination (ClinicalTrials.gov number, NCT00286637). PMID:18515577

Association Between Retinal Nerve Fiber Layer Thickness and Abnormalities of Vision in People With Human Immunodeficiency Virus Infection

PubMed Central

Kalyani, Partho S.; Holland, Gary N.; Fawzi, Amani A.; Arantes, Tiago E.F.; Yu, Fei; Sadun, Alfredo A.

2014-01-01

Purpose To investigate relationships between contrast sensitivity (CS), color vision, and retinal nerve fiber layer (RNFL) among people with human immunodeficiency virus (HIV) infection; to evaluate the effect of time since diagnosis of HIV infection on RNFL thickness. Design Noninterventional cross-sectional study. Methods We evaluated 102 eyes of 57 HIV-infected individuals without ocular opportunistic infections. Peripapillary RNFL thickness was determined with spectraldomain optical coherence tomography in 4 quadrants. CS was measured with the Pelli-Robson technique (expressed as logCS); color vision was measured with the Lanthony desaturated 15-hue technique (expressed as color confusion index [C-index], with higher scores indicating worse color vision). Correlations between values were assessed using Spearman correlation coefficients. Results Median RNFL thickness (average of 4 quadrants) was 102.9 μm (range, 75.0–134.7 μm). Median logCS was 1.90 (range, 1.25–1.95). Median C-index was 1.58 (range, 0.96–4.07). Temporal RNFL thickness was correlated with logCS (r = 0.295, P = .003) and C-index (r = −0.338, P = .0005). Time since diagnosis of HIV infection was shorter for those with thick average RNFL than for those with thin average RNFL (P = .18). Conclusions Both worse CS and worse color vision are correlated with thinning of the temporal RNFL, with possible threshold effects. Increased prevalences of abnormal CS and abnormal color vision in this population are therefore likely attributable to neuroretinal compromise. This pattern of structural and functional losses may reflect preferential damage to small-caliber axons in the maculopapillary bundle, possibly associated with mitochondrial dysfunction, providing a potential disease mechanism for HIV-associated “neuroretinal disorder.” PMID:22245459

Comparison of Foveal, Macular, and Peripapillary Intraretinal Thicknesses Between Autism Spectrum Disorder and Neurotypical Subjects.

PubMed

García-Medina, José Javier; García-Piñero, María; Del-Río-Vellosillo, Mónica; Fares-Valdivia, Jesarán; Ragel-Hernández, Ana Belén; Martínez-Saura, Salvador; Cárcel-López, María Dolores; Zanon-Moreno, Vicente; Pinazo-Duran, María Dolores; Villegas-Pérez, María Paz

2017-11-01

To compare thicknesses of intraretinal layers segmented by spectral-domain optical coherence tomography (SD-OCT) between autism spectrum disorder (ASD) and neurotypical (NT) individuals. We performed 2 scans on 108 eyes from 54 participants (27 high-functioning ASD and 27 age- and sex-matched NT subjects): macular fast volume and peripapillary retinal nerve fiber layer (pRNFL). Macula was automatically segmented. The mean foveal and macular thickness of nine different layers and the thickness of nine pRNFL sectors were considered. Data from the right and left eyes were averaged for each participant. The results were compared between the ASD and NT groups. Associations between the Kaufman brief intelligence test (K-BIT), head circumference and SD-OCT results were also investigated in ASD individuals. ASD subjects showed greater foveal thickness at total retina, total inner retina, inner plexiform and inner nuclear layers, and greater macular thickness at total retina and total inner retina. Inferior, nasal inferior and temporal inferior sectors of pRNFL were also thicker in the ASD participants than in the controls (P < 0.05, unpaired t-test). Significant correlations were found between some K-BIT results and temporal inferior and inferior pRNFL thicknesses in the ASD group (P < 0.05, Spearman's rank correlation). No associations were seen between head circumference and OCT parameters. There are intraretinal thickenings at different locations in ASD subjects when compared to NT controls. This fact should be taken into account when interpreting SD-OCT examinations in ASD individuals. Plus, some pRNFL thicknesses present positive correlations with scores of cognitive status in ASD.

Quantitative Trait Locus Analysis of SIX1-SIX6 with Retinal Nerve Fiber Layer Thickness in Individuals of European Descent

PubMed Central

Kuo, Jane Z.; Zangwill, Linda M.; Medeiros, Felipe A.; Liebmann, Jeffery M.; Girkin, Christopher A.; Hammel, Na’ama; Rotter, Jerome I.; Weinreb, Robert N.

2015-01-01

Purpose To perform a quantitative trait locus (QTL) analysis and evaluate whether a locus between SIX1 and SIX6 is associated with retinal nerve fiber layer (RNFL) thickness in individuals of European descent. Design Observational, multi-center, cross-sectional study. Methods 231 participants were recruited from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. Association of rs10483727 in SIX1-SIX6 with global and sectoral RNFL thickness was performed. Quantitative trait analysis with the additive model of inheritance was analyzed using linear regression. Trend analysis was performed to evaluate the mean global and sectoral RNFL thickness with 3 genotypes of interest (T/T, C/T, C/C). All models were adjusted for age and gender. Results Direction of association between T allele and RNFL thickness was consistent in the global and different sectoral RNFL regions. Each copy of the T risk allele in rs10483727 was associated with −0.16 μm thinner global RNFL thickness (β=−0.16, 95% CI: −0.28 to −0.03; P=0.01). Similar patterns were found for the sectoral regions, including inferior (P=0.03), inferior-nasal (P=0.017), superior-nasal (P=0.0025), superior (P=0.002) and superior-temporal (P=0.008). The greatest differences were observed in the superior and inferior quadrants, supporting clinical observations for RNFL thinning in glaucoma. Thinner global RNFL was found in subjects with T/T genotypes compared to subjects with C/T and C/C genotypes (P=0.044). Conclusions Each copy of the T risk allele has an additive effect and was associated with thinner global and sectoral RNFL. Findings from this QTL analysis further support a genetic contribution to glaucoma pathophysiology. PMID:25849520

Retinal nerve fiber layer thinning: a window into rapid eye movement sleep behavior disorders in Parkinson's disease.

PubMed

Yang, Zi-Jiao; Wei, Jing; Mao, Cheng-Jie; Zhang, Jin-Ru; Chen, Jing; Ji, Xiao-Yan; Liu, Jun-Yi; Shen, Yun; Xiong, Kang-Ping; Huang, Jun-Ying; Yang, Ya-Ping; Liu, Chun-Feng

2016-12-01

Retinal nerve fiber layer (RNFL) thinning occurs in Parkinson's disease (PD) and other neurodegenerative diseases. Idiopathic RBD (iRBD) is a well-established prodromal hallmark of synucleinopathies and occurs secondary to many neurodegenerative diseases, including PD. The aim of this study is to determine whether or not retinal structures are altered with the onset of rapid eye movement (REM) sleep behavior disorders (RBD). In all, a total of 63 patients with PD, 14 patients with idiopathic RBD, and 26 sex- and age-matched healthy controls were enrolled and underwent optical coherence tomography measurements (HD-OCT (Zeiss) ) for the average and every quadrant of RNFL thickness. The REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ) was used to classify PD patients with clinically probable RBD (PD + pRBD) or without probable RBD (PD - pRBD). Patients with iRBD were identified by polysomnography. For patients with RBD (idiopathic or secondary to PD), we found a significant decrease in RNFL thickness compared with groups without RBD (PD - pRBD and healthy controls) (all p < 0.05). Average RNFL thickness in patients with iRBD is significantly thinner than in healthy controls (p < 0.05). In PD, the average RNFL thickness was dramatically thinner in the PD + pRBD group than the PD - pRBD group (p < 0.005). Compared with healthy controls, RNFL thickness was slightly thinner in the drug-naive PD group but not the PD group with drug treatment. Multiple linear regression analysis showed that RBDSQ score was negatively associated with average and inferior RNFL variation in PD (all p < 0.005). The findings show that RNFL was slightly but significantly thinner in idiopathic RBD. In PD, RNFL thickness may vary depending on the presence of RBD.

Peripapillary Retinoschisis in Glaucoma Patients

PubMed Central

Bayraktar, Serife; Cebeci, Zafer; Kabaalioglu, Melis; Ciloglu, Serife; Kir, Nur; Izgi, Belgin

2016-01-01

Purpose. To investigate peripapillary retinoschisis and its effect on retinal nerve fiber layer (RNFL) thickness measurements by using spectral-domain optical coherence tomography (SD-OCT) in glaucomatous eyes. Methods. Circumpapillary RNFL (cpRNFL) B-scan images of 940 glaucoma patients (Group 1) and 801 glaucoma-suspect patients (Group 2) obtained by SD-OCT were reviewed. The structural and clinical characteristics of the retinoschisis were investigated. The RNFL thickness measurements taken at the time of retinoschisis diagnosis and at the follow-up visits were also compared. Results. Twenty-nine retinoschisis areas were found in 26 of the 940 glaucoma patients (3.1%) in Group 1 and seven areas were found in 801 patients (0.87%) in Group 2. In glaucomatous eyes, the retinoschisis was attached to the optic disc and overlapped with the RNFL defect. At the time of retinoschisis, the RNFL thickness was statistically greater in the inferior temporal quadrant when compared with the follow-up scans (p < 0.001). No macular involvement or retinal detachment was observed. Conclusion. The present study investigated 33 peripapillary retinoschisis patients. Increase in RNFL thickness measurements was observed at the time of retinoschisis. It is important to examine the cpRNFL B-scan images of glaucoma patients so that the RNFL thickness is not overestimated. PMID:27069674

Peripapillary Retinoschisis in Glaucomatous Eyes

PubMed Central

Lee, Eun Ji; Kim, Tae-Woo; Kim, Mijin; Choi, Yun Jeong

2014-01-01

Purpose To investigate the structural and clinical characteristics of peripapillary retinoschisis observed in glaucomatous eyes using spectral-domain optical coherence tomography (SD-OCT). Methods Circumpapillary retinal nerve fiber layer (cpRNFL) and macular cross-hair SD-OCT scans and infrared fundus images of the glaucoma patients from the Investigating Glaucoma Progression Study (IGPS) and healthy volunteers were reviewed. Optic disc images obtained using enhanced depth imaging (EDI) SD-OCT were also evaluated. The structural characteristics and clinical course of the retinoschisis associated with glaucoma were investigated. Results Twenty-five retinoschisis areas were found in 22 of the 372 patients (5.9%) included in the IGPS, and in 1 area in 1 of 187 healthy control subjects (0.5%). In the 22 glaucomatous eyes with retinoschisis, the schisis was attached to the optic disc and overlapped with the retinal nerve fiber layer (RNFL) defect. The RNFL was the layer most commonly affected by the retinoschisis, either alone or together with other deeper layers. Acquired optic disc pit was identified in 8 eyes on disc photography and/or B-scan images obtained by EDI SD-OCT. Spontaneous resolution of this condition was observed in nine eyes. No retinal detachment or macular involvement of the retinoschisis was observed in any of the eyes. Multivariate analysis showed a significant influence of a higher intraocular pressure at SD-OCT scanning on the presence of retinoschisis (Odds ratio  = 1.418, P = 0.001). Conclusions The present study investigated 22 cases of peripapillary retinoschisis in glaucomatous eyes. The retinoschisis was attached to the optic nerve and topographically correlated with RNFL defect. It often resolved spontaneously without causing severe visual disturbance. Care should be taken not to overestimate the RNFL thickness in eyes with retinoschisis, and also not to misinterpret the resolution of retinoschisis as a rapid glaucomatous RNFL deterioration. PMID:24587238

Retinal and Optic Nerve Degeneration in Patients with Multiple Sclerosis Followed up for 5 Years.

PubMed

Garcia-Martin, Elena; Ara, Jose R; Martin, Jesus; Almarcegui, Carmen; Dolz, Isabel; Vilades, Elisa; Gil-Arribas, Laura; Fernandez, Francisco J; Polo, Vicente; Larrosa, Jose M; Pablo, Luis E; Satue, Maria

2017-05-01

To quantify retinal nerve fiber layer (RNFL) changes in patients with multiple sclerosis (MS) and healthy controls with a 5-year follow-up and to analyze correlations between disability progression and RNFL degeneration. Observational and longitudinal study. One hundred patients with relapsing-remitting MS and 50 healthy controls. All participants underwent a complete ophthalmic and electrophysiologic exploration and were re-evaluated annually for 5 years. Visual acuity (Snellen chart), color vision (Ishihara pseudoisochromatic plates), visual field examination, optical coherence tomography (OCT), scanning laser polarimetry (SLP), and visual evoked potentials. Expanded Disability Status Scale (EDSS) scores, disease duration, treatments, prior optic neuritis episodes, and quality of life (QOL; based on the 54-item Multiple Sclerosis Quality of Life Scale score). Optical coherence tomography (OCT) revealed changes in all RNFL thicknesses in both groups. In the MS group, changes were detected in average thickness and in the mean deviation using the GDx-VCC nerve fiber analyzer (Laser Diagnostic Technologies, San Diego, CA) and in the P100 latency of visual evoked potentials; no changes were detected in visual acuity, color vision, or visual fields. Optical coherence tomography showed greater differences in the inferior and temporal RNFL thicknesses in both groups. In MS patients only, OCT revealed a moderate correlation between the increase in EDSS and temporal and superior RNFL thinning. Temporal RNFL thinning based on OCT results was correlated moderately with decreased QOL. Multiple sclerosis patients exhibit a progressive axonal loss in the optic nerve fiber layer. Retinal nerve fiber layer thinning based on OCT results is a useful marker for assessing MS progression and correlates with increased disability and reduced QOL. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Assessment of Retinal Nerve Fiber Layer Using Optical Coherence Tomography and Scanning Laser Polarimetry in Progressive Glaucomatous Optic Neuropathy

PubMed Central

Sehi, Mitra; Greenfield, David S.

2006-01-01

Purpose To describe a case of progressive glaucomatous optic neuropathy using scanning laser polarimetry with fixed (SLP-FCC) and variable corneal compensation (SLP-VCC) and optical coherence tomography (OCT). Design Observational case report. Methods A 21-year-old male with juvenile primary open-angle glaucoma developed progression because of noncompliance with therapy. The patient underwent dilated stereoscopic examination and photography of the optic disk, standard automated perimetry (SAP), OCT, and SLP imaging with FCC and VCC at the baseline examination and after four years of follow-up. Results Optic disk, retinal nerve fiber layer (RNFL) atrophy, and SAP progression was observed. Reduction in mean RNFL thickness (average, superior, inferior) was 18, 18, and 27 microns (OCT); 22, 40, and 17 microns (SLP-FCC); and 6, 12, and 12 microns (SLP-VCC), respectively. Conclusions This case demonstrates that digital imaging of the peripapillary RNFL is capable of documentation and measurement of progressive glaucomatous RNFL atrophy. PMID:17157591

Progressive Retinal Nerve Fiber Layer Atrophy Associated With Enlarging Peripapillary Pit.

PubMed

Lee, Eun Ji; Kim, Tae-Woo

2017-02-01

To report a case in which progressive retinal nerve fiber layer (RNFL) atrophy was observed along with enlargement of the peripapillary pit. A 34-year-old male was diagnosed with primary open-angle glaucoma and followed up for 4 years with regular ophthalmic examinations. Both eyes were myopic (-10 D, OD and -10.5 D, OS), and untreated intraocular pressures were 18 mm Hg (OD) and 16 mm Hg (OS). A subtle depression of the superotemporal peripapillary area was deepened and emerged as a peripapillary pit during the follow-up period. With the enlargement of the peripapillary pit, a RNFL defect at the location of pit widened and thinned continuously. The enlargement of the pit was documented by the spectral-domain optical coherence tomography posterior pole scanning. Progressive RNFL atrophy was observed with enlargement of the peripapillary pit. The finding suggests that tensile stress derived from the scleral stretching may have significant influence on the integrity of the RNFL.

Comparison between the Correlations of Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomography and Visual Field Defects in Standard Automated White-on-White Perimetry versus Pulsar Perimetry.

PubMed

Alnawaiseh, Maged; Hömberg, Lisann; Eter, Nicole; Prokosch, Verena

2017-01-01

To compare the structure-function relationships between retinal nerve fiber layer thickness (RNFLT) and visual field defects measured either by standard automated perimetry (SAP) or by Pulsar perimetry (PP). 263 eyes of 143 patients were prospectively included. Depending on the RNFLT, patients were assigned to the glaucoma group (group A: RNFL score 3-6) or the control group (group B: RNFL score 0-2). Structure-function relationships between RNFLT and mean sensitivity (MS) measured by SAP and PP were analyzed. Throughout the entire group, the MS assessed by PP and SAP correlated significantly with RNFLT in all sectors. In the glaucoma group, there was no significant difference between the correlations RNFL-SAP and RNFL-PP, whereas a significant difference was found in the control group. In the control group, the correlation between structure and function based on the PP data was significantly stronger than that based on SAP.

Optical coherence tomography measurement of the retinal nerve fiber layer in normal and juvenile glaucomatous eyes.

PubMed

Mrugacz, Malgorzata; Bakunowicz-Lazarczyk, Alina

2005-01-01

The aim of this study was to quantitatively assess and compare the thickness of the retinal nerve fiber layer (RNFL) in normal and glaucomatous eyes of children using the optical coherence tomograph. The mean RNFL thickness of normal eyes (n=26) was compared with that of glaucomatous eyes (n=26). The eyes were classified into diagnostic groups based on conventional ophthalmological physical examination, Humphrey 30-2 visual fields, stereoscopic optic nerve head photography, and optical coherence tomography. The mean RNFL was significantly thinner in glaucomatous eyes than in normal eyes: 95+/-26.3 and 132+/-24.5 microm, respectively. More specifically, the RNFL was significantly thinner in glaucomatous eyes than in normal eyes in the inferior quadrant: 87+/-23.5 and 122+/-24.2 microm, respectively. The mean and inferior quadrant RFNL thicknesses as measured by the optical coherence tomograph showed a statistically significant correlation with glaucoma. Optical coherence tomography may contribute to tracking of juvenile glaucoma progression. Copyright (c) 2005 S. Karger AG, Basel.

Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography.

PubMed

Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K W; Yoshimura, Nagahisa

2016-01-01

To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction.

Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography

PubMed Central

Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K. W.; Yoshimura, Nagahisa

2016-01-01

Purpose To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. Methods The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Results Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. Conclusions The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction. PMID:26814541

Diagnostic power of optic disc morphology, peripapillary retinal nerve fiber layer thickness, and macular inner retinal layer thickness in glaucoma diagnosis with fourier-domain optical coherence tomography.

PubMed

Huang, Jehn-Yu; Pekmezci, Melike; Mesiwala, Nisreen; Kao, Andrew; Lin, Shan

2011-02-01

To evaluate the capability of the optic disc, peripapillary retinal nerve fiber layer (P-RNFL), macular inner retinal layer (M-IRL) parameters, and their combination obtained by Fourier-domain optical coherent tomography (OCT) in differentiating a glaucoma suspect from perimetric glaucoma. Two hundred and twenty eyes from 220 patients were enrolled in this study. The optic disc morphology, P-RNFL, and M-IRL were assessed by the Fourier-domain OCT (RTVue OCT, Model RT100, Optovue, Fremont, CA). A linear discriminant function was generated by stepwise linear discriminant analysis on the basis of OCT parameters and demographic factors. The diagnostic power of these parameters was evaluated with receiver operating characteristic (ROC) curve analysis. The diagnostic power in the clinically relevant range (specificity ≥ 80%) was presented as the partial area under the ROC curve (partial AROC). The individual OCT parameter with the largest AROC and partial AROC in the high specificity (≥ 80%) range were cup/disc vertical ratio (AROC = 0.854 and partial AROC = 0.142) for the optic disc parameters, average thickness (AROC = 0.919 and partial AROC = 0.147) for P-RNFL parameters, inferior hemisphere thickness (AROC = 0.871 and partial AROC = 0.138) for M-IRL parameters, respectively. The linear discriminant function further enhanced the ability in detecting perimetric glaucoma (AROC = 0.970 and partial AROC = 0.172). Average P-RNFL thickness is the optimal individual OCT parameter to detect perimetric glaucoma. Simultaneous evaluation on disc morphology, P-RNFL, and M-IRL thickness can improve the diagnostic accuracy in diagnosing glaucoma.

Inner retinal thinning after Brilliant Blue G-assisted internal limiting membrane peeling for vitreoretinal interface disorders.

PubMed

Ambiya, Vikas; Goud, Abhilash; Khodani, Mitali; Chhablani, Jay

2017-04-01

The aim of this study was to evaluate ganglion cell layer and nerve fiber layer thickness after Brilliant Blue G (BBG)-assisted internal limiting membrane (ILM) peeling for vitreomacular disorders. Retrospective analysis of spectral domain optical coherence tomography (SD-OCT) of 42 eyes of 42 patients, who underwent pars plana vitrectomy with BBG-assisted ILM peeling, was performed. Inclusion criteria were idiopathic macular hole, idiopathic vitreomacular traction, and idiopathic epiretinal membrane. Key exclusion criteria were vitreoretinal interface abnormalities secondary to any other diseases, follow-up period of less than 3 months, and any other associated retinal pathology. Average, minimum, and sectoral ganglion cell, and inner plexiform layers (GCIPL) and retinal nerve fiber layer (RNFL) parameters were collected. Changes in these parameters from baseline to 3- and 6-month visits after surgery were analyzed. At 3 months after surgery, we found a statistically significant reduction in the average GCIPL thickness (P = 0.031) and also in the superior sectors (P < 0.05) compared to the baseline values. A similar reduction was observed in the minimum RNFL thickness (P = 0.028) as well as in the superior sectoral RNFL thickness (P < 0.05). In 14 eyes with 6 months of follow-up, a similar statistically significant thinning of the GCIPL and RNFL was observed. However, the difference between the 3-month and 6-month values was not statistically significant (P = 0.679). BBG-assisted ILM peeling for vitreomacular interface disorders leads to thinning of the inner retina including GCIPL and RNFL. These structural changes should be correlated with retinal function tests to explore the pros and cons of this surgical step.

Thinner retinal layers are associated with changes in the visual pathway: A population-based study.

PubMed

Mutlu, Unal; Ikram, Mohammad K; Roshchupkin, Gennady V; Bonnemaijer, Pieter W M; Colijn, Johanna M; Vingerling, Johannes R; Niessen, Wiro J; Ikram, Mohammad A; Klaver, Caroline C W; Vernooij, Meike W

2018-06-23

Increasing evidence shows that thinner retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), assessed on optical coherence tomography (OCT), are reflecting global brain atrophy. Yet, little is known on the relation of these layers with specific brain regions. Using voxel-based analysis, we aimed to unravel specific brain regions associated with these retinal layers. We included 2,235 persons (mean age: 67.3 years, 55% women) from the Rotterdam Study (2007-2012) who had gradable retinal OCT images and brain magnetic resonance imaging (MRI) scans, including diffusion tensor (DT) imaging. Thicknesses of peripapillary RNFL and perimacular GCL were measured using an automated segmentation algorithm. Voxel-based morphometry protocols were applied to process DT-MRI data. We investigated the association between retinal layer thickness with voxel-wise gray matter density and white matter microstructure by performing linear regression models. We found that thinner RNFL and GCL were associated with lower gray matter density in the visual cortex, and with lower fractional anisotropy and higher mean diffusivity in white matter tracts that are part of the optic radiation. Furthermore, thinner GCL was associated with lower gray matter density of the thalamus. Thinner RNFL and GCL are associated with gray and white matter changes in the visual pathway suggesting that retinal thinning on OCT may be specifically associated with changes in the visual pathway rather than with changes in the global brain. These findings may serve as a basis for understanding visual symptoms in elderly patients, patients with Alzheimer's disease, or patients with posterior cortical atrophy. © 2018 Wiley Periodicals, Inc.

Reproducibility of peripapillary retinal nerve fiber layer thickness with spectral domain cirrus high-definition optical coherence tomography in normal eyes.

PubMed

Hong, Samin; Kim, Chan Yun; Lee, Won Seok; Seong, Gong Je

2010-01-01

To assess the reproducibility of the new spectral domain Cirrus high-definition optical coherence tomography (HD-OCT; Carl Zeiss Meditec, Dublin, CA, USA) for analysis of peripapillary retinal nerve fiber layer (RNFL) thickness in healthy eyes. Thirty healthy Korean volunteers were enrolled. Three optic disc cube 200 x 200 Cirrus HD-OCT scans were taken on the same day in discontinuous sessions by the same operator without using the repeat scan function. The reproducibility of the calculated RNFL thickness and probability code were determined by the intraclass correlation coefficient (ICC), coefficient of variation (CV), test-retest variability, and Fleiss' generalized kappa (kappa). Thirty-six eyes were analyzed. For average RNFL thickness, the ICC was 0.970, CV was 2.38%, and test-retest variability was 4.5 microm. For all quadrants except the nasal, ICCs were 0.972 or higher and CVs were 4.26% or less. Overall test-retest variability ranged from 5.8 to 8.1 microm. The kappa value of probability codes for average RNFL thickness was 0.690. The kappa values of quadrants and clock-hour sectors were lower in the nasal areas than in other areas. The reproducibility of Cirrus HD-OCT to analyze peripapillary RNFL thickness in healthy eyes was excellent compared with the previous reports for time domain Stratus OCT. For the calculated RNFL thickness and probability code, variability was relatively higher in the nasal area, and more careful analyses are needed.

The Relationship between Retinal Ganglion Cell Axon Constituents and Retinal Nerve Fiber Layer Birefringence in the Primate

PubMed Central

Pocock, Ginger M.; Aranibar, Roberto G.; Kemp, Nate J.; Specht, Charles S.; Markey, Mia K.; Rylander, H.G.

2009-01-01

Purpose To determine the degree of correlation between spatial characteristics of the retinal nerve fiber layer (RNFL) birefringence (ΔnRNFL) surrounding the optic nerve head (ONH) with the corresponding anatomy of retinal ganglion cell (RGC) axons and their respective organelles. Methods RNFL phase retardation per unit depth (PR/UD, proportional to ΔnRNFL) was measured in two cynomolgus monkeys using enhanced polarization-sensitive optical coherence tomography (EPS-OCT). The monkeys were perfused with glutaraldehyde and eyes were enucleated and prepared for transmission electron microscopy (TEM) histological analysis. Morphological measurements from TEM images were used to estimate values of neurotubule density (ρRNFL), axoplasmic area (Ax) mode, axon area (Aa) mode, slope (u) of neurotubule number versus axoplasmic area [neurotubule packing density], fractional area of axoplasm in the nerve fiber bundle (f), mitochondrial fractional area in the nerve fiber bundle (xm), mitochondriated axon profile fraction (mp), and length of axonal membrane profiles per unit nerve fiber bundle area (Lam/Ab). Registered PR/UD and morphological parameters from corresponding angular sections were then correlated using Pearson’s correlation and multi-level models. Results In one eye, there was a statistically significant correlation between PR/UD and ρRNFL (r = 0.67, P =0.005) and between PR/UD and neurotubule packing density (r = 0.70, P = 0.002). Correlation coefficients of r = 0.81 (P=0.01) and r = 0.50 (P = 0.05) were observed between PR/UD and (Ax) mode for each respective subject. Conclusion Neurotubules are the primary source of birefringence in the RNFL of the primate retina. PMID:19494208

Deep Defects Seen on Visual Fields Spatially Correspond Well to Loss of Retinal Nerve Fiber Layer Seen on Circumpapillary OCT Scans.

PubMed

Mavrommatis, Maria A; Wu, Zhichao; Naegele, Saskia I; Nunez, Jason; De Moraes, Carlos; Ritch, Robert; Hood, Donald C

2018-02-01

To examine the structure-function relationship in glaucoma between deep defects on visual fields (VF) and deep losses in the circumpapillary retinal nerve fiber layer (cpRNFL) on optical coherence tomography (OCT) circle scans. Thirty two glaucomatous eyes with deep VF defects, as defined by at least one test location worse than ≤ -15 dB on the 10-2 and/or 24-2 VF pattern deviation (PD) plots, were included from 87 eyes with "early" glaucoma (i.e., 24-2 mean deviation better than -6 dB). Using the location of the deep VF points and a schematic model, the location of local damage on an OCT circle scan was predicted. The thinnest location of cpRNFL (i.e., deepest loss) was also determined. In 19 of 32 eyes, a region of complete or near complete cpRNFL loss was observed. All 19 of these had deep VF defects on the 24-2 and/or 10-2. All of the 32 eyes with deep VF defects had abnormal cpRNFL regions (red, 1%) and all but 2 had a region of cpRNFL thickness <21 μm. The midpoint of the VF defect and the location of deepest cpRNFL had a 95% limit of agreement within approximately two-thirds of a clock-hour (or 30°) sector (between -22.1° to 25.2°). Individual fovea-to-disc angle (FtoDa) adjustment improved agreement in one eye with an extreme FtoDa. Although studies relating local structural (OCT) and functional (VF) measures typically show poor to moderate correlations, there is good qualitative agreement between the location of deep cpRNFL loss and deep defects on VFs.

Retina nerve fiber layer and choroidal thickness changes in obstructive sleep apnea syndrome.

PubMed

Ozge, Gokhan; Dogan, Deniz; Koylu, Mehmet Talay; Ayyildiz, Onder; Akincioglu, Dorukcan; Mumcuoglu, Tarkan; Mutlu, Fatih Mehmet

2016-01-01

The purpose of this study was to determine the effects of obstructive sleep apnea syndrome (OSAS) on the submacular and peripapillary retinal nerve fiber layer (RNFL) and choroidal thickness (ChT). Eighty-four eyes of 42 male patients with OSAS and 112 eyes of 56 aged-matched and body mass index-matched healthy male subjects were enrolled in this case-control study. The ChT and peripapillary RNFL thickness was measured using enhanced depth imaging optical coherence tomography. The ChT and RNFL thickness measurements of the groups were compared, and correlations among the Apnea Hypopnea Index (AHI) values and these measurements were calculated. Right and left eyes were separately evaluated. There were no significant differences in the subfoveal and temporal ChT between the groups (p > 0.05). The OSAS group had significantly thicker ChT at 0.5 and 1.5 mm nasal to the fovea in both eyes than the control group (p < 0.05). The peripapillary ChT were significantly thicker in the OSAS group at all segments except for the temporal and superotemporal segments when compared with the control group (p < 0.05 for all quadrants except temporal and superotemporal). When compared with controls, the OSAS group had significantly thinner nasal RNFL thickness in the right eye (p = 0.01) and thinner mean RNFL thickness in both eyes (p < 0.001). Other RNFL thickness measurements were similar between groups (p > 0.05). Between AHI and mean RNFL thickness showed a median negative correlation (r = - 0.411, p = 0.001). The choroidal thickening in patients with OSAS may be associated with the pathophysiology of the neurodegeneration process of the disease.

Effect of diabetic retinopathy and panretinal photocoagulation on retinal nerve fiber layer and optic nerve appearance.

PubMed

Lim, Michele C; Tanimoto, Suzana A; Furlani, Bruno A; Lum, Brent; Pinto, Luciano M; Eliason, David; Prata, Tiago S; Brandt, James D; Morse, Lawrence S; Park, Susanna S; Melo, Luiz A S

2009-07-01

To determine if panretinal photocoagulation (PRP) alters retinal nerve fiber layer (RNFL) thickness and optic nerve appearance. Patients with diabetes who did and did not undergo PRP and nondiabetic control subjects were enrolled in a prospective study. Participants underwent optical coherence tomography of the peripapillary retina and optic nerve. Stereoscopic optic nerve photographs were graded in a masked fashion. Ninety-four eyes of 48 healthy individuals, 89 eyes of 55 diabetic patients who did not undergo PRP, and 37 eyes of 24 subjects with diabetes who underwent PRP were included in this study. Eyes that had been treated with PRP had thinner peripapillary RNFL compared with the other groups; this was statistically significantly different in the inferior (P = .004) and nasal (P = .003) regions. Optic nerve cupping did not increase with severity of disease classification, but the proportion of optic nerves graded as suspicious for glaucoma or as having nonglaucomatous optic neuropathy did (P = .008). These grading categories were associated with thinner RNFL measurements. Diabetic eyes that have been treated with PRP have thinner RNFL than nondiabetic eyes. Optic nerves in eyes treated with PRP are more likely to be graded as abnormal, but their appearance is not necessarily glaucomatous and may be related to thinning of the RNFL.

Determinants of peripapillary retinal nerve fiber layer thickness regarding ocular and systemic parameters - the MIPH Eye&Health Study.

PubMed

Schuster, Alexander Karl-Georg; Fischer, Joachim Ernst; Vossmerbaeumer, Christine; Vossmerbaeumer, Urs

2016-10-01

Optical coherence tomography (OCT) allows quantitative image analysis of retinal tissue in vivo. Peripapillary retinal nerve fiber layer (pRNFL) thickness is widely used for evaluation of retinal nerve fiber rarefaction in several optic neuropathies. This study evaluates associations of pRNFL thickness in healthy adult subjects in order to evaluate influencing factors. A cross-sectional study was performed in a working-age population. Only eyes without detectable ocular pathologies were included in the analysis. Among analyzed systemic cardiovascular parameters were age, gender, body-mass index, mean arterial blood pressure, HbA1c, high- and low-density-lipoproteins, and triglycerides. A comprehensive ophthalmological examination including refraction, tonometry, keratometry, and central corneal thickness measurmentwas performed. In addition, pRNFL thickness was imaged by spectral-domain OCT. Univariable and multivariable associations of pRNFL thickness in all four quadrants and on average with systemic and ocular parameters were calculated using a generalized estimating equation model. Three hundred and six subjects were included. pRNFL thickness measurements showed a significant association with spherical equivalent: pRNFL thickness decreased with increasing myopia in all quadrants (multivariable regression coefficients Beta: superior: 1.16, 95 % CI [0.62;1.71], p < 0.001; temporal: 0.87, [0.33;1.41], p = 0.001; inferior: 1.80, [1.18;2.42], p < 0.001; nasal: 2.60, [2.01;3.20], p < 0.001) and on average (1.51, [1.20;1.82], p < 0.001). A thicker central cornea thickness was related to lower pRNFL in the superior (-0.05, [-0.10; -0.01], p = 0.01), the inferior quadrant (-0.05, [-0.10;0.00], p = 0.03) and on average (-0.04, [-0.07; -0.01], p = 0.02). All other parameters were not  associated. Our findings highlight the importance of refraction when evaluating pRNFL thickness and its independence from other systemic parameters.

Evaluation of a Myopic Normative Database for Analysis of Retinal Nerve Fiber Layer Thickness.

PubMed

Biswas, Sayantan; Lin, Chen; Leung, Christopher K S

2016-09-01

Analysis of retinal nerve fiber layer (RNFL) abnormalities with optical coherence tomography in eyes with high myopia has been complicated by high rates of false-positive errors. An understanding of whether the application of a myopic normative database can improve the specificity for detection of RNFL abnormalities in eyes with high myopia is relevant. To evaluate the diagnostic performance of a myopic normative database for detection of RNFL abnormalities in eyes with high myopia (spherical equivalent, -6.0 diopters [D] or less). In this cross-sectional study, 180 eyes with high myopia (mean [SD] spherical equivalent, -8.0 [1.8] D) from 180 healthy individuals were included in the myopic normative database. Another 46 eyes with high myopia from healthy individuals (mean [SD] spherical equivalent, -8.1 [1.8] D) and 74 eyes from patients with high myopia and glaucoma (mean [SD] spherical equivalent, -8.3 [1.9] D) were included for evaluation of specificity and sensitivity. The 95th and 99th percentiles of the mean and clock-hour circumpapillary RNFL thicknesses and the individual superpixel thicknesses of the RNFL thickness map measured by spectral-domain optical coherence tomography were calculated from the 180 eyes with high myopia. Participants were recruited from January 2, 2013, to December 30, 2015. The following 6 criteria of RNFL abnormalities were examined: (1) mean circumpapillary RNFL thickness below the lower 95th or (2) the lower 99th percentile; (3) one clock-hour or more for RNFL thickness below the lower 95th or (4) the lower 99th percentile; and (5) twenty contiguous superpixels or more of RNFL thickness in the RNFL thickness map below the lower 95th or (6) the lower 99th percentile. Specificities and sensitivities for detection of RNFL abnormalities. Of the 46 healthy eyes and 74 eyes with glaucoma studied (from 39 men and 38 women), the myopic normative database showed a higher specificity (63.0%-100%) than did the built-in normative database of the optical coherence tomography instrument (8.7%-87.0%) for detection of RNFL abnormalities across all the criteria examined (differences in specificities between 13.0% [95% CI, 1.1%-24.9%; P = .01] and 54.3% [95% CI, 37.8%-70.9%; P < .001]) except for the criterion of mean RNFL thickness below the lower 99th percentile, in which both normative databases had the same specificities (100%) but the myopic normative database exhibited a higher sensitivity (71.6% vs 86.5%; difference in sensitivities, 14.9% [95% CI, 4.6%-25.1%; P = .002]). The application of a myopic normative database improved the specificity without compromising the sensitivity compared with the optical coherence tomography instrument's built-in normative database for detection of RNFL abnormalities in eyes with high myopia. Inclusion of myopic normative databases should be considered in optical coherence tomography instruments.

Optic coherence tomography shows inflammation and degeneration in major depressive disorder patients correlated with disease severity.

PubMed

Kalenderoglu, Aysun; Çelik, Mustafa; Sevgi-Karadag, Ayse; Egilmez, Oguzhan Bekir

2016-11-01

Previous research has consistently detected inflammation in the etiology of depression and neuroimaging studies have demonstrated gray matter abnormalities implying a neurodegenerative process in depression. The aim of this study was to compare ganglion cell layer (GCL), and inner plexiform layer (IPL) volumes and retinal nerve fiber layer (RNFL) thickness between first episode and recurrent major depressive disorder (MDD) patients and controls using optic coherence tomography (OCT) in order to detect findings supporting a degenerative process. Also choroid thicknesses of the same groups were compared to examine effects of inflammation on MDD. This study included 50 recurrent MDD patients, 50 first episode MDD patients and 50 controls. OCT measurements were performed by a spectral OCT device. GCL and IPL volumes and RNFL and choroid thicknesses were measured automatically by the device. GCL and IPL volumes were significantly smaller in recurrent depression patients than first episode patients and in all MDD patients than controls. Also there were significant negative correlations between their volumes and disease severity parameters such as Ham-D and CGI scores, and disease duration. RNFL thicknesses were also lower in recurrent MDD patients than first episode patients and all MDD patients than controls but statistical significance was achieved only for global RNFL and temporal superior RNFL. Mean choroid thickness was higher in MDD patients than controls and in first episode MDD patients than recurrent MDD patients. Cross-sectional design of our study limits conclusions about progressive degeneration during the course of MDD. Lack of a control neuroimaging method like magnetic resonance imaging makes it hard to draw firm conclusions from our results. OCT finding of decreased GCL and IPL volumes supports previous research suggesting degeneration in MDD. OCT may be an important tool to track neurodegeneration in patients with major depression. Considering RNFL to be the latest layer that will be affected during course of degeneration, GCL and IPL volumes appear to be better parameters to follow. In addition, choroid may be an important structure to detect acute attack period and to follow inflammatory process in MDD like in systemic inflammatory diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of Ganglion Cell and Retinal Nerve Fiber Layer Thickness in Pigment Dispersion Syndrome, Pigmentary Glaucoma, and Healthy Subjects with Spectral-domain OCT.

PubMed

Arifoglu, Hasan Basri; Simavli, Huseyin; Midillioglu, Inci; Berk Ergun, Sule; Simsek, Saban

2017-01-01

To evaluate the ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) thickness in pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) with RTVue spectral domain optical coherence tomography (SD-OCT). A total of 102 subjects were enrolled: 29 with PDS, 18 with PG, and 55 normal subjects. Full ophthalmic examination including visual field analysis was performed. SD-OCT was used to analyze GCC superior, GCC inferior, and average RNFL thickness. To compare the discrimination capabilities, the areas under the receiver operating characteristic curves were assessed. Superior GCC, inferior GCC, and RNFL thickness values of patients with PG were statistically signicantly lower than those of patients with PDS (p < 0.001) and healthy individuals (p < 0.001 for all). No statistically significant difference was found between PDS and normal subjects in same parameters (p > 0.05). The SD-OCT-derived GCC and RNFL thickness parameters can be useful to discriminate PG from both PDS and normal subjects.

Comparison between the Correlations of Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomography and Visual Field Defects in Standard Automated White-on-White Perimetry versus Pulsar Perimetry

PubMed Central

Hömberg, Lisann; Eter, Nicole

2017-01-01

Purpose To compare the structure-function relationships between retinal nerve fiber layer thickness (RNFLT) and visual field defects measured either by standard automated perimetry (SAP) or by Pulsar perimetry (PP). Materials and Methods 263 eyes of 143 patients were prospectively included. Depending on the RNFLT, patients were assigned to the glaucoma group (group A: RNFL score 3–6) or the control group (group B: RNFL score 0–2). Structure-function relationships between RNFLT and mean sensitivity (MS) measured by SAP and PP were analyzed. Results Throughout the entire group, the MS assessed by PP and SAP correlated significantly with RNFLT in all sectors. In the glaucoma group, there was no significant difference between the correlations RNFL-SAP and RNFL-PP, whereas a significant difference was found in the control group. Conclusions In the control group, the correlation between structure and function based on the PP data was significantly stronger than that based on SAP. PMID:29119021

Macular Ganglion Cell and Retinal Nerve Fiber Layer Thickness in Children With Refractive Errors-An Optical Coherence Tomography Study.

PubMed

Goh, Jody P; Koh, Victor; Chan, Yiong Huak; Ngo, Cheryl

2017-07-01

To study the distribution of macular ganglion cell-inner plexiform layer (GC-IPL) thickness and peripapillary retinal nerve fiber layer (RNFL) thickness in children with refractive errors. Two hundred forty-three healthy eyes from 139 children with refractive error ranging from -10.00 to +5.00 D were recruited from the National University Hospital Eye Surgery outpatient clinic. After a comprehensive ocular examination, refraction, and axial length (AL) measurement (IOLMaster), macular GC-IPL and RNFL thickness values were obtained with a spectral domain Cirrus high definition optical coherence tomography system (Carl Zeiss Meditec Inc.). Only scans with signal strength of >6/10 were included. Correlation between variables was calculated using the Pearson correlation coefficient. A multivariate analysis using mixed models was done to adjust for confounders. The mean spherical equivalent refraction was -3.20±3.51 D and mean AL was 24.39±1.72 mm. Average, minimum, superior, and inferior GC-IPL were 82.59±6.29, 77.17±9.65, 83.68±6.96, and 81.64±6.70 μm, respectively. Average, superior, and inferior peripapillary RNFL were 99.00±11.45, 123.20±25.81, and 124.24±22.23 μm, respectively. Average, superior, and inferior GC-IPL were correlated with AL (β=-2.056, P-value 0.000; β=-2.383, P-value 0.000; β=-1.721, P-value 0.000), but minimum GC-IPL was not (β=-1.056, P-value 0.115). None of the RNFL parameters were correlated with AL. This study establishes normative macular GC-IPL and RNFL thickness in children with refractive errors. Our results suggest that high definition optical coherence tomography RNFL parameters and minimum GC-IPL are not affected by AL or myopia in children, and therefore warrants further evaluation in pediatric glaucoma patients.

Retinal Nerve Fiber Layer and Peripapillary Choroidal Thicknesses in Non-Glaucomatous Unilateral Optic Atrophy Compared with Unilateral Advanced Pseudoexfoliative Glaucoma.

PubMed

Kucukevcilioglu, Murat; Ayyildiz, Onder; Aykas, Seckin; Gokce, Gokcen; Koylu, Mehmet Talay; Ozgonul, Cem; Ozge, Gokhan; Mumcuoglu, Tarkan; Yumusak, Erhan

2017-02-01

To investigate retinal nerve fiber layer thickness (RNFL-T) and peripapillary choroidal thickness (PC-T) in non-glaucomatous optic atrophy (OA) patients in comparison with unaffected and control eyes, furthermore, to compare thickness profiles with unilateral pseudoexfoliative advanced glaucoma. Thirty-three eyes with OA (Group A), 33 unaffected fellow eyes (Group B), 25 right eyes of 25 control subjects (Group C), and 15 eyes with advanced glaucoma (Group D) were enrolled. RNFL-T was measured in six regions by spectral-domain optical coherence tomography. Enhanced depth imaging optical coherence tomography was obtained to evaluate PC-T in corresponding regions. RNFL-T was significantly lower in Group A than in Groups B and C globally and at all peripapillary regions (all p < 0.001). P-CT in Group A was significantly lower globally (p = 0.03) and in three regions (temporal, p = 0.001; temporal-superior, p = 0.01; and nasal-inferior, p = 0.037) versus Group C. However, it was significantly thinner than in Group B in all regions (temporal, p = 0.02; temporal-superior, p = 0.013; nasal-superior, p = 0.044; nasal, p = 0.02; nasal-inferior, p < 0.001; and temporal-inferior, p < 0.001) and globally (p < 0.001). In Group A RNFL-T (thicker superiorly and inferiorly; thinner temporally and nasally) and PC-T (superior > temporal > nasal > inferior) profiles were almost identical to that in unaffected fellow eyes and control eyes. However, Group D showed different patterns with less regional differences in RNFL-T, and the greatest value of PC-T in nasal quadrant. Besides retinal nerve fiber layer thinning, non-glaucomatous OA is associated with choroidal thinning. The RNFL-T and PC-T profiles in advanced glaucoma eyes differed from the common patterns seen among OA eyes, unaffected fellow eyes, and control eyes.

Effect of cataract surgery on retinal nerve fiber layer thickness parameters using scanning laser polarimetry (GDxVCC).

PubMed

Dada, Tanuj; Behera, Geeta; Agarwal, Anand; Kumar, Sanjeev; Sihota, Ramanjit; Panda, Anita

2010-01-01

To study the effect of cataract extraction on the retinal nerve fiber layer (RNFL) thickness, and assessment by scanning laser polarimetry (SLP), with variable corneal compensation (GDx VCC), at the glaucoma service of a tertiary care center in North India. Thirty-two eyes of 32 subjects were enrolled in the study. The subjects underwent RNFL analysis by SLP (GDx VCC) before undergoing phacoemulsification cataract extraction with intraocular lens (IOL) implantation (Acrysof SA 60 AT) four weeks following cataract surgery. The RNFL thickness parameters evaluated both before and after surgery included temporal, superior, nasal, inferior, temporal (TSNIT) average, superior average, inferior average, and nerve fiber index (NFI). The mean age of subjects was 57.6 +/- 11.7 years (18 males, 14 females). Mean TSNIT average thickness (microm) pre- and post-cataract surgery was 49.2 +/- 14.1 and 56.5 +/- 7.6 ( P = 0.001). There was a statistically significant increase in RNFL thickness parameters (TSNIT average, superior average, and inferior average) and decrease in NFI post-cataract surgery as compared to the baseline values. Mean NFI pre- and post-cataract surgery was 41.3 +/- 15.3 and 21.6 +/- 11.8 ( P = 0.001). Measurement of RNFL thickness parameters by scanning laser polarimetry is significantly altered following cataract surgery. Post the cataract surgery, a new baseline needs to be established for assessing the longitudinal follow-up of a glaucoma patient. The presence of cataract may lead to an underestimation of the RNFL thickness, and this should be taken into account when analyzing progression in a glaucoma patient.

Evaluation of the Ganglion Cell Complex and Retinal Nerve Fiber Layer in Low, Moderate, and High Myopia: A Study by RTVue Spectral Domain Optical Coherence Tomography.

PubMed

Sezgin Akcay, Betul Ilkay; Gunay, Betul Onal; Kardes, Esra; Unlu, Cihan; Ergin, Ahmet

2017-01-01

To assess the effect of low, moderate, and high myopia on the thickness of the retinal nerve fiber layer (RNFL) and Ganglion cell complex (GCC) measured by Spectral Domain Optical Coherence Tomography (SD-OCT) in non-glaucomatous subjects. The subjects were divided into three groups: low (n = 81, 35.6%), moderate (n = 79, 34.8%), and highly myopic eyes (n = 67, 29.5%). The RNFL thickness profile, including the average, superior, nasal, inferior, and temporal quadrant and each of the eight directional thicknesses, was measured. GCC parameters, including the average, superior, and inferior values, the focal loss volume (FLV), and the global loss volume (GLV), were measured. The correlation between the OCT measurements and the axial length was evaluated. The average, superior, inferior, and nasal RNFL thicknesses of low and moderate myopic eyes were found to be significantly higher than those of highly myopic eyes. The temporal RNFL thicknesses were not different among the three groups. The average, superior, and inferior ganglion cell complex values of low and moderate myopic eyes were significantly higher than those of highly myopic eyes. The FLV and GLV of low and moderate myopic eyes were significantly higher than those of highly myopic eyes (p = 0.001 for all). In the moderate and high myopia groups, the average RNFL thickness and GCC thickness were both negatively correlated with the axial length. Highly myopic subjects tend to have thinner RNFL and GCC thicknesses than subjects with low and moderate myopia.

Abnormal retinal nerve fiber layer thickness and macula lutea in patients with mild cognitive impairment and Alzheimer's disease.

PubMed

Gao, LiYan; Liu, Ying; Li, XiaoHong; Bai, QuanHao; Liu, Ping

2015-01-01

We investigated possible abnormalities in the retinal nerve fiber layer (RNFL) and macula lutea of patients diagnosed with Alzheimer's disease (AD) and mild cognitive impairment (MCI) and tested for any correlation with the severity of dementia. A total of 72 subjects, comprising 25 AD patients, 26 MCI patients and 21 healthy individuals (controls) were enrolled in this study. The thickness of the RNFL and volume of the macula lutea was determined using optical coherence tomography (OCT). When compared with controls, we found statistically significant thinning of the RNFL in AD patients at all clock-hour positions except 12:00, and nasal quadrant, 2:00, 3:00 and 4:00. After adjusting several risk factors, the average thickness of the RNFL was reduced in MCI patients compared to AD patients, with specific reductions at inferior quadrant, 5:00 and 6:00. Compared to controls, MCI patients showed a significant decrease in RNFL thickness only in the temporal quadrant, 8:00, 9:00 and 10:00. We found significant reduction in the volume of the macula lutea both in AD and MCI patients. Finally, we could not establish any correlation between patient Mini-Mental State Examination (MMSE) scores (an estimation of the severity of cognitive impairment) and any OCT parameter. Retinal degeneration in AD and MCI patients results in decreased thickness of the RNFL, and reduced macular volume in AD and MCI patients. However, there seems to be no correlation between these changes and the severity of dementia. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Reflectance Speckle of Retinal Nerve Fiber Layer Reveals Axonal Activity

PubMed Central

Huang, Xiang-Run; Knighton, Robert W.; Zhou, Ye; Zhao, Xiao-Peng

2013-01-01

Purpose. This study investigated the retinal nerve fiber layer (RNFL) reflectance speckle and tested the hypothesis that temporal change of RNFL speckle reveals axonal dynamic activity. Methods. RNFL reflectance speckle of isolated rat retinas was studied with monochromatic illumination. A series of reflectance images was collected every 5 seconds for approximately 15 minutes. Correlation coefficients (CC) of selected areas between a reference and subsequent images were calculated and plotted as a function of the time intervals between images. An exponential function fit to the time course was used to evaluate temporal change of speckle pattern. To relate temporal change of speckle to axonal activity, in vitro living retina perfused at a normal (34°C) and a lower (24°C) temperature, paraformaldehyde-fixed retina, and retina treated with microtubule depolymerization were used. Results. RNFL reflectance was not uniform; rather nerve fiber bundles had a speckled texture that changed with time. In normally perfused retina, the time constant of the CC change was 0.56 ± 0.26 minutes. In retinas treated with lower temperature and microtubule depolymerization, the time constants increased by two to four times, indicating that the speckle pattern changed more slowly. The speckled texture in fixed retina was stationary. Conclusions. Fixation stops axonal activity; treatments with either lower temperature or microtubule depolymerization are known to decrease axonal transport. The results obtained in this study suggest that temporal change of RNFL speckle reveals structural change due to axonal activity. Assessment of RNFL reflectance speckle may offer a new means of evaluating axonal function. PMID:23532525

Specific Location of Disc Hemorrhage is Linked to Nerve Fiber Layer Defects.

PubMed

Yoo, Young Cheol; Kim, Joon Mo; Park, Han Seok; Yoo, Chungkwon; Shim, Seong Hee; Won, Yu Sam; Park, Ki Ho; Chang, Robert T

2017-06-01

To investigate the relationship between retinal nerve fiber layer (RNFL) defects and the quadrant and proximal location of disc hemorrhages (DHs) in a large population examined for health screening. A total of 168,044 subjects older than 20 years underwent a single screening ophthalmic examination with color fundus photography as part of a comprehensive health screening program. The presence and location of DHs and RNFL defects were assessed. The DH locations were defined according to the quadrant location (inferotemporal, superotemporal, inferonasal, or superonasal) and the most proximal end of DHs relative to the disc center (cup base, cup margin, disc rim, or extrapapillary region). Using these two location descriptors as independent variables, a logistic regression analysis was conducted to explore the effects of DH location on RNFL defects. Two hundred twenty-six eyes had DH and 120 (53.1%) of them had RNFL defects. After adjusting for proximal location, DHs located in the inferotemporal quadrant accompanied RFNL defects 12 times more frequently than those in the superonasal quadrant (odds ratio [OR], 11.81; P = .004). Conversely, after adjusting for quadrant location, the ORs for an associated RNFL defect were 3.73 (P < .001), 16.54 (P < .001), and 8.91 (P = .002) for DHs with the proximal end at the disc rim, cup margin, and cup base, respectively. Among the four quadrants and four proximal locations, DHs were identified most frequently in the inferotemporal quadrant and outside the disc, respectively. Some DH locations, such as the inferotemporal quadrant and the cup margin, were associated with RNFL defects, whereas others were not.

Retinal nerve fiber layer and macular thinning in systemic lupus erythematosus: an optical coherence tomography study comparing SLE and neuropsychiatric SLE.

PubMed

Liu, G Y; Utset, T O; Bernard, J T

2015-10-01

Due to the lack of reliable biomarkers in diagnosing and monitoring neuropsychiatric systemic lupus erythematosus (NPSLE), the aim of this study was to examine the utility of measurements obtained through spectral domain optical coherence tomography (SD-OCT) as a biomarker for NP involvement in SLE. Retinal nerve fiber layer (RNFL) and macula scans were performed using SD-OCT on 15 NPSLE patients, 16 SLE patients without NP symptoms (non-NP SLE), and 16 healthy controls. Macular volume and thickness of the central macula and peripapillary RNFL were compared between the groups and to scores on two validated cognitive tests. NPSLE patients did not differ significantly from non-NP SLE patients in retinal thickness or macular volume. However, SLE patients as a whole showed significant RNFL and macular thinning compared to controls. Scores on the Trail Making Test B, a test of complex attention, showed significant correlation to temporal superior and temporal inferior RNFL thickness. Our results demonstrate RNFL thinning in SLE, and confirm the previous finding of high incidence of abnormal brain scans in SLE. These findings suggest that OCT measurements may be indicative of neurodegeneration in SLE and may be a useful biomarker for early cognitive impairment in SLE. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Progressive Chronic Retinal Axonal Loss Following Acute Methanol-Induced Optic Neuropathy: Four-Year Prospective Cohort Study.

PubMed

Nurieva, Olga; Diblik, Pavel; Kuthan, Pavel; Sklenka, Petr; Meliska, Martin; Bydzovsky, Jan; Heissigerova, Jarmila; Urban, Pavel; Kotikova, Katerina; Navratil, Tomas; Komarc, Martin; Seidl, Zdenek; Vaneckova, Manuela; Pelclova, Daniela; Zakharov, Sergey

2018-04-27

To study the dynamics and clinical determinants of chronic retinal nerve fiber layer thickness (RNFL) loss after methanol-induced optic neuropathy. Prospective cohort study. All patients underwent complete ophthalmic evaluation including SD-OCT three times during four years of observation:4.9[±0.6], 25.0[±0.6], and 49.9[±0.5] months after discharge. Eighty-four eyes of 42 survivors of methanol poisoning; mean age (standard deviation) of 45.7[±4.4] years, and 82 eyes of 41 controls; mean age 44.0[±4.2] years. global and temporal RNFL loss. Abnormal RNFL thickness was registered in 13/42(31%) survivors of methanol poisoning and chronic axonal loss in 10/42(24%) patients. Significant decrease of global/temporal RNFL thickness during the observation period was found in the study population compared to the controls (p<0.001). The risk estimate of chronic global RNFL loss for arterial blood pH<7.3 at admission was: 11.65(1.91-71.12;95%CI) after adjusting for age and sex. The patients with chronic axonal degeneration demonstrated progressive visual loss in 7/10 cases. The patients with abnormal RNFL thickness had magnetic resonance signs of brain damage in 10/13 versus 8/29 cases with normal RNFL thickness (p=0.003). Signs of brain hemorrhages were present in 7/13 patients with abnormal RNFL thickness versus 5/29 cases with normal RNFL thickness (p=0.015). Methanol-induced optic neuropathy may lead to chronic retinal axonal loss during the following years. Arterial blood pH on admission is the strongest predictor of chronic RNFL thickness decrease. Chronic retinal neurodegeneration is associated with the progressive loss of visual functions and necrotic brain lesions. Copyright © 2018. Published by Elsevier Inc.

Reduced retinal nerve fiber layer (RNFL) thickness in ALS patients: a window to disease progression.

PubMed

Rohani, Mohammad; Meysamie, Alipasha; Zamani, Babak; Sowlat, Mohammad Mahdi; Akhoundi, Fahimeh Haji

2018-04-30

To assess RNFL thickness in ALS patients and compare it to healthy controls, and to detect possible correlations between RNFL thickness in ALS patients and disease severity and duration. Study population consisted of ALS patients and age- and sex-matched controls. We used the revised ALS functional rating scale (ALSFRS-R) as a measure of disease severity. RNFL thickness in the four quadrants were measured with a spectral domain OCT (Topcon 3D, 2015). We evaluated 20 ALS patients (40 eyes) and 25 healthy matched controls. Average RNFL thickness in ALS patients was significantly reduced compared to controls (102.57 ± 13.46 compared to 97.11 ± 10.76, p 0.04). There was a significant positive correlation between the functional abilities of the patients based on the ALSFRS-R and average RNFL thickness and also RNFL thickness in most quadrants. A linear regression analysis proved that this correlation was independent of age. In ALS patients, RNFL thickness in the nasal quadrant of the left eyes was significantly reduced compared to the corresponding quadrant in the right eyes even after adjustment for multiplicity (85.80 ± 23.20 compared to 96.80 ± 16.96, p = 0.008). RNFL thickness in ALS patients is reduced compared to healthy controls. OCT probably could serve as a marker of neurodegeneration and progression of the disease in ALS patients. RNFL thickness is different among the right and left eyes of ALS patients pointing to the fact that asymmetric CNS involvement in ALS is not confined to the motor system.

Ganglion cell complex scan in the early prediction of glaucoma.

PubMed

Ganekal, S

2012-01-01

To compare the macular ganglion cell complex (GCC) with peripapillary retinal fiber layer (RNFL) thickness map in glaucoma suspects and patients. Forty participants (20 glaucoma suspects and 20 glaucoma patients) were enrolled. Macular GCC and RNFL thickness maps were performed in both eyes of each participant in the same visit. The sensitivity and specificity of a color code less than 5% (red or yellow) for glaucoma diagnosis were calculated. Standard Automated Perimetry was performed with the Octopus 3.1.1 Dynamic 24-2 program. The statistical analysis was performed with the SPSS 10.1 (SPSS Inc. Chicago, IL, EUA). Results were expressed as mean +/- standard deviation and a p value of 0.05 or less was considered significant. Provide absolute numbers of these findings with their units of measurement. There was a statistically significant difference in average RNFL thickness (p=0.004), superior RNFL thickness (p=0.006), inferior RNFL thickness (p=0.0005) and average GCC (p=0.03) between the suspects and glaucoma patients. There was no difference in optic disc area (p=0.35) and vertical cup/disc ratio (p=0.234) in both groups. While 38% eyes had an abnormal GCC and 13% had an abnormal RNFL thickness in the glaucoma suspect group, 98% had an abnormal GCC and 90% had an abnormal RNFL thickness in the glaucoma group. The ability to diagnose glaucoma with macular GCC thickness is comparable to that with peripapillary RNFL thickness . Macular GCC thickness measurements may be a good alternative or a complementary measurement to RNFL thickness assessment in the clinical evaluation of glaucoma. © NEPjOPH.

Diagnostic ability of macular ganglion cell-inner plexiform layer thickness in glaucoma suspects.

PubMed

Xu, Xiaoyu; Xiao, Hui; Guo, Xinxing; Chen, Xiangxi; Hao, Linlin; Luo, Jingyi; Liu, Xing

2017-12-01

The purpose is to assess the diagnostic ability for early glaucoma of macular ganglion cell-inner plexiform layer (GCIPL) thickness in a Chinese population including glaucoma suspects.A total of 367 eyes with primary open-angle glaucoma (168 early glaucoma, 78 moderate glaucoma, and 121 advanced glaucoma), 52 eyes with ocular hypertension (OHT), 59 eyes with enlarged cup-to-disc ratio (C/D), and 225 normal eyes were included. GCIPL thickness (average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal), retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters were measured using Cirrus high-definition optical coherence tomography (OCT) and compared. The diagnostic ability of OCT parameters was assessed by area under receiver operating characteristic curve (AUROC) in 3 distinguishing groups: normal eyes and eyes with early glaucoma, normal eyes and eyes with glaucoma regardless of disease stage, and nonglaucomatous eyes (normal eyes, eyes with OHT, and enlarged C/D) and early glaucomatous eyes.Glaucomatous eyes showed a significant reduction in GCIPL thickness compared with nonglaucomatous eyes. In all 3 distinguishing groups, best-performing parameters of GCIPL thickness, RNFL thickness, and ONH parameters were minimum GCIPL thickness (expressed in AUROC, 0.899, 0.952, and 0.900, respectively), average RNFL thickness (0.904, 0.953, and 0.892, respectively), and rim area (0.861, 0.925, and 0.824, respectively). There was no statistical significance of AUROC between minimum GCIPL thickness and average RNFL thickness (all P > .05).GCIPL thickness could discriminate early glaucoma from normal and glaucoma suspects with good sensitivity and specificity. The glaucoma diagnostic ability of GCIPL thickness was comparable to that of RNFL thickness. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

Regional vascular density-visual field sensitivity relationship in glaucoma according to disease severity.

PubMed

Shin, Joong Won; Lee, Jiyun; Kwon, Junki; Choi, Jaewan; Kook, Michael S

2017-12-01

To study whether there are global and regional relationships between peripapillary vascular density (pVD) assessed by optical coherence tomography angiography (OCT-A) and visual field (VF) mean sensitivity at different glaucoma stages. Microvascular images and peripapillary retinal nerve fibre layer (pRNFL) thicknesses were obtained using a Cirrus OCT-A device in 91 glaucoma subjects. The pVD was measured at various spatial locations according to the Garway-Heath map, using a MATLAB software (The MathWorks, Natick, Massachusetts). VF mean sensitivity (VFMS) was recorded in the 1/L scale. Global and regional vasculature-function (pVD vs VFMS) relationships were assessed in separate patient groups at mild and moderate-to-advanced stages of glaucoma. The pVDs at superotemporal and inferotemporal regions were significantly associated with corresponding VFMS in mild glaucoma (p<0.05). In moderate-to-advanced glaucoma, there were significant associations between pVD and VFMS, regardless of location. The association between global pVD and VFMS was significantly stronger than that between global pRNFL thickness and VFMS in moderate-to-advanced stage glaucoma (p <0.05). Global and regional pVD measured by OCT-A was significantly associated with corresponding VFMS in moderate-to-advanced glaucoma. OCT-A may be useful in monitoring glaucoma at various stages. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Rates of retinal nerve fiber layer thinning in glaucoma suspect eyes

PubMed Central

Miki, Atsuya; Medeiros, Felipe A.; Weinreb, Robert N.; Jain, Sonia; He, Feng; Sharpsten, Lucie; Khachatryan, Naira; Hammel, Na’ama; Liebmann, Jeffrey M.; Girkin, Christopher A.; Sample, Pamela A.; Zangwill, Linda M.

2015-01-01

Purpose To compare the rates of retinal nerve fiber layer (RNFL) loss in patients suspect of having glaucoma who developed visual field damage (VFD) to those who did not develop VFD, and to determine whether the rate of RNFL loss can be used to predict who will develop VFD.. Design Prospective observational cohort study Participants Glaucoma suspects, defined as having glaucomatous optic neuropathy or ocular hypertension (Intraocular pressure (IOP)>21 mmHg) without repeatable VFD at baseline from the Diagnostic Innovations in Glaucoma Study, and the African Descent and Glaucoma Evaluation Study. Methods Global and quadrant RNFL thickness (RNFLT) were measured with the Spectralis spectral-domain optical coherence tomography (SD-OCT). VFD was defined as having 3 consecutive abnormal visual fields. The rate of RNFL loss in eyes developing VFD was compared with eyes not developing VFD using multivariable linear mixed-effects models. A joint longitudinal survival model utilized the estimated RNFLT slope to predict the risk of developing VFD, while adjusting for potential confounding variables. Main Outcome Measures The rate of RNFL thinning and the probability of developing VFD. Results Four hundred and fifty-four eyes of 294 glaucoma suspects were included. The average number of SD-OCT examinations was 4.6 (range, 2–9) with median follow-up time of 2.2 (0.4–4.1) years. Forty eyes (8.8%) developed VFD. The estimated mean rate of global RNFL loss was significantly faster in eyes developing VFD compared with eyes that did not (−2.02μm/year vs. −0.82μm/year, P<0.001). The joint longitudinal survival model showed that each 1μm/year faster rate of global RNFL loss corresponded to a 2.05 times higher risk of developing VFD (Hazards Ratio (HR)=2.05, 95% Confidence Interval (CI): 1.14–3.71; p=0.017). Conclusions The rate of global RNFL loss was more than twice as fast in eyes developing VFD compared with eyes that did not develop them. Joint longitudinal survival model showed that a 1μm/year faster rate of RNFLT loss corresponded to a 2.05 times higher risk of developing VFD. These results suggest that measuring the rate of SD-OCT RNFL loss may be a useful tool to help identify patients who are at a high risk of developing visual field loss. PMID:24629619

Registration of adaptive optics corrected retinal nerve fiber layer (RNFL) images

PubMed Central

Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

2014-01-01

Glaucoma is the leading cause of preventable blindness in the western world. Investigation of high-resolution retinal nerve fiber layer (RNFL) images in patients may lead to new indicators of its onset. Adaptive optics (AO) can provide diffraction-limited images of the retina, providing new opportunities for earlier detection of neuroretinal pathologies. However, precise processing is required to correct for three effects in sequences of AO-assisted, flood-illumination images: uneven illumination, residual image motion and image rotation. This processing can be challenging for images of the RNFL due to their low contrast and lack of clearly noticeable features. Here we develop specific processing techniques and show that their application leads to improved image quality on the nerve fiber bundles. This in turn improves the reliability of measures of fiber texture such as the correlation of Gray-Level Co-occurrence Matrix (GLCM). PMID:24940551

Registration of adaptive optics corrected retinal nerve fiber layer (RNFL) images.

PubMed

Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

2014-06-01

Glaucoma is the leading cause of preventable blindness in the western world. Investigation of high-resolution retinal nerve fiber layer (RNFL) images in patients may lead to new indicators of its onset. Adaptive optics (AO) can provide diffraction-limited images of the retina, providing new opportunities for earlier detection of neuroretinal pathologies. However, precise processing is required to correct for three effects in sequences of AO-assisted, flood-illumination images: uneven illumination, residual image motion and image rotation. This processing can be challenging for images of the RNFL due to their low contrast and lack of clearly noticeable features. Here we develop specific processing techniques and show that their application leads to improved image quality on the nerve fiber bundles. This in turn improves the reliability of measures of fiber texture such as the correlation of Gray-Level Co-occurrence Matrix (GLCM).

Discriminating ability of Cirrus and RTVue optical coherence tomography in different stages of glaucoma

PubMed Central

Mittal, Deepti; Dubey, Suneeta; Gandhi, Monica; Pegu, Julie; Bhoot, Madhu; Gupta, Yadunandan Prasad

2018-01-01

Purpose: The aim of this study is to determine which parameter of Cirrus and RTVue optical coherence tomography (OCT) has the highest ability to discriminate between early, moderate, and advanced glaucoma. Simultaneously, to compare the performance of the two OCT devices in terms of their ability to differentiate the three stages of glaucoma. Further, to analyze the macular parameters of both devices and compare them with the conventional retinal nerve fiber layer (RNFL) parameters. Methods: One hundred and twenty eyes (30 healthy and 90 glaucomatous [30 mild, 30 moderate, and 30 advanced glaucoma]) of 65 participants (15 healthy, 50 glaucomatous [15 mild, 15 moderate, and 20 advanced glaucoma]) underwent Cirrus and RTVue OCT scanning on a single visit. Results: Average RNFL thickness and superior RNFL thickness of both the devices and inferior (ganglion cell complex [GCC] of RTVue device best differentiated normals from all stage glaucomatous eyes (P > 0.05). Cirrus average RNFL thickness and superior RNFL thickness performed better than other parameters (P < 0.05) in differentiating early glaucoma from moderate and advanced. In differentiating advanced from early and moderate glaucoma, RTVue average, superior, and inferior RNFL thickness and inferior GCC parameters had the highest discriminating ability (P < 0.05). Conclusion: Overall, average RNFL thickness had the highest ability to distinguish different stages of the disease. No significant difference was found between RTVue and Cirrus OCT device in different severity levels. No significant difference was observed between RNFL and macular parameters in different stages of glaucoma. PMID:29676314

Discriminating ability of Cirrus and RTVue optical coherence tomography in different stages of glaucoma.

PubMed

Mittal, Deepti; Dubey, Suneeta; Gandhi, Monica; Pegu, Julie; Bhoot, Madhu; Gupta, Yadunandan Prasad

2018-05-01

The aim of this study is to determine which parameter of Cirrus and RTVue optical coherence tomography (OCT) has the highest ability to discriminate between early, moderate, and advanced glaucoma. Simultaneously, to compare the performance of the two OCT devices in terms of their ability to differentiate the three stages of glaucoma. Further, to analyze the macular parameters of both devices and compare them with the conventional retinal nerve fiber layer (RNFL) parameters. One hundred and twenty eyes (30 healthy and 90 glaucomatous [30 mild, 30 moderate, and 30 advanced glaucoma]) of 65 participants (15 healthy, 50 glaucomatous [15 mild, 15 moderate, and 20 advanced glaucoma]) underwent Cirrus and RTVue OCT scanning on a single visit. Average RNFL thickness and superior RNFL thickness of both the devices and inferior (ganglion cell complex [GCC] of RTVue device best differentiated normals from all stage glaucomatous eyes (P > 0.05). Cirrus average RNFL thickness and superior RNFL thickness performed better than other parameters (P < 0.05) in differentiating early glaucoma from moderate and advanced. In differentiating advanced from early and moderate glaucoma, RTVue average, superior, and inferior RNFL thickness and inferior GCC parameters had the highest discriminating ability (P < 0.05). Overall, average RNFL thickness had the highest ability to distinguish different stages of the disease. No significant difference was found between RTVue and Cirrus OCT device in different severity levels. No significant difference was observed between RNFL and macular parameters in different stages of glaucoma.

Ability of Cirrus™ HD-OCT Optic Nerve Head Parameters to Discriminate Normal from Glaucomatous Eyes

PubMed Central

Mwanza, Jean-Claude; Oakley, Jonathan D; Budenz, Donald L; Anderson, Douglas R

2010-01-01

Purpose To determine the ability of optic nerve head (ONH) parameters measured with spectral domain Cirrus™ HD-OCT to discriminate between normal and glaucomatous eyes and to compare them to the discriminating ability of peripapillary retinal nerve fiber layer (RNFL) thickness measurements performed with Cirrus™ HD-OCT. Design Evaluation of diagnostic test or technology. Participants Seventy-three subjects with glaucoma and one hundred and forty-six age-matched normal subjects. Methods Peripapillary ONH parameters and RNFL thickness were measured in one randomly selected eye of each participant within a 200×200 pixel A-scan acquired with Cirrus™ HD-OCT centered on the ONH. Main Outcome Measures ONH topographic parameters, peripapillary RNFL thickness, and the area under receiver operating characteristic curves (AUCs). Results For distinguishing normal from glaucomatous eyes, regardless of disease stage, the six best parameters (expressed as AUC) were vertical rim thickness (VRT, 0.963), rim area (RA, 0.962), RNFL thickness at clock-hour 7 (0.957), RNFL thickness of the inferior quadrant (0.953), vertical cup-to-disc ratio (VCDR, 0.951) and average RNFL thickness (0.950). The AUC for distinguishing between normal and eyes with mild glaucoma was greatest for RNFL thickness of clock-hour 7 (0.918), VRT (0.914), RA (0.912), RNFL thickness of inferior quadrant (0.895), average RNFL thickness (0.893) and VCDR (0.890). There were no statistically significant differences between AUCs for the best ONH parameters and RNFL thickness measurements (p > 0.05). Conclusions Cirrus™ HD-OCT ONH parameters are able to discriminate between eyes that are normal from those with glaucoma or even mild glaucoma. There is no difference in the ability of ONH parameters and RNFL thickness measurement, as measured with Cirrus™ OCT, to distinguish between normal and glaucomatous eyes. PMID:20920824

Microstructure of β-zone parapapillary atrophy and rate of retinal nerve fiber layer thinning in primary open-angle glaucoma.

PubMed

Kim, Yong Woo; Lee, Eun Ji; Kim, Tae-Woo; Kim, Mijin; Kim, Hyunjoong

2014-07-01

To investigate whether the rate of retinal nerve fiber layer (RNFL) thinning differs according to the microstructure of β-zone parapapillary atrophy (PPA) as evaluated by spectral-domain (SD) optical coherence tomography (OCT) in primary open-angle glaucoma (POAG). Prospective, observational, comparative study. A total of 195 eyes with POAG that had been evaluated by serial SD-OCT RNFL thickness measurements for ≥ 2 years. On the basis of the extent of Bruch's membrane (BM) within the β-zone PPA (area without retinal pigment epithelium [RPE]), as shown in the infrared fundus images, PPA was divided into PPA+BM (PPA with intact BM) and PPA-BM (PPA devoid of BM). Eyes were categorized into group A (having PPA+BM only, n=64), group B (having both PPA+BM and PPA-BM, n=58), group C (having PPA-BM only, n=32), and group D (without β-zone PPA, n=41). The rate of progressive OCT RNFL thinning was determined by linear regression and compared between groups. Factors influencing the rate of RNFL thinning were evaluated, including age, sex, follow-up duration, history of filtering surgery, baseline RNFL thickness, baseline intraocular pressure (IOP), mean IOP and IOP fluctuation during follow-up, PPA types, baseline PPA width, PPA width increase, axial length (AXL), central corneal thickness, and visual field mean deviation (MD). Rate of thinning of OCT RNFL thicknesses over time. Patients in groups B and C were significantly younger and more myopic, and had a greater AXL, than those in groups A and D (all P<0.001). The rate of global RNFL thinning was significantly faster in group A (-1.66 ± 2.94 μm/year) than in the other groups (group B, -0.87 ± 1.28 μm/year; group C, 0.20 ± 1.86 μm/year; group D, -0.28 ± 1.74 μm/year; P = 0.001). Multivariate regression showed a significant association of shorter follow-up period (P = 0.016), greater baseline global RNFL thickness (P = 0.035), type of β-zone PPA (group A, P = 0.023), and greater baseline PPA+BM width (P = 0.034) with a faster rate of RNFL thinning. The rate of RNFL thinning differed according to the microstructure of β-zone PPA. It was faster for eyes with β-zone PPA with intact BM than for eyes without β-zone PPA or with β-zone PPA devoid of BM. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Alterations in retinal nerve fiber layer thickness in early stages of diabetic retinopathy and potential risk factors.

PubMed

Shi, Rui; Guo, Zhonglan; Wang, Feng; Li, Rong; Zhao, Lei; Lin, Rong

2018-02-01

To investigate the loss of retinal nerve fiber layer (RNFL) in type-2 diabetic patients with early-stage diabetic retinopathy (DR) and to identify potential risk factors accounting for these alterations. In this cross-sectional study, 158 type-2 diabetic patients were divided into three groups based on their DR status. RNFL thickness and other optic disc parameters were obtained by optical coherence tomography (OCT) and then compared among different groups. We investigated the potential association between RNFL loss and systemic risk factors for DR, including diabetes duration, body mass index (BMI), serum lipids, hemoglobin A1c (HbA1c) and albumin-creatinine ratio (ACR). One-way ANOVA was carried out to compare RNFL thickness among different groups, Pearson correlation and multivariate linear regression analysis were performed to determine potential risk factors related to RNFL thickness in these patients. There were significant differences in the average (F = 8.872, P = 0.003), superior (F = 8.769, P = 0.004), and inferior (F = 8.857, P = 0.003) RNFL thickness of both eyes among the groups, but no obvious difference in optic disc parameters was found. Diabetic duration, BMI, TG, High density lipoprotein cholesterol (HDL), HbA1c, and ACR were found negatively related to the RNFL thickness in both or single eye according to Pearson correlation analysis. After controlling for age, gender, and axis length (AL) in multivariate linear regression analysis, the diabetic duration was associated significantly with RNFL thickness of superior in both eye (right eye: p = 0.016, left eye: p = 0.024), BMI was related to the nasal quadrant of the right eye (p = 0.034), and TG was related to the inferior of the right eye (p = 0.037), HbA1c (p = 0.026) was associated significantly with the average RNFL thickness of the right eye. In addition, ACR was found negatively related to average (p = 0.042) and inferior quadrant (p = 0.014) of the left eye, respectively. RNFL loss might be the earliest structural change of retina in diabetic patients, and associated with diabetic duration, BMI, TG, HbA1c, and ACR. The conclusions of this study need to be proved by other well-matched and large-scale prospective clinical trials in the future, because the correlations discovered in our study were weak.

Evaluation of Retinal Changes in Progressive Supranuclear Palsy and Parkinson Disease.

PubMed

Gulmez Sevim, Duygu; Unlu, Metin; Gultekin, Murat; Karaca, Cagatay; Mirza, Meral; Mirza, Galip Ertugrul

2018-06-01

Differentiating Parkinson disease (PD) from progressive supranuclear palsy (PSP) can be challenging early in the clinical course. The aim of our study was to see if specific retinal changes could serve as a distinguishing feature. We used spectral domain optical coherence tomography (SD-OCT) with automatic segmentation to measure peripapillary nerve fiber layer thickness and the thickness and volume of retinal layers at the macula. Thicknesses of superior peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell layer, inner plexiform layer, inner nuclear layer, and macular volume were more affected in PSP compared with PD (P < 0.05). Thicker inferotemporal pRNFL and lower macular volume were detected in levodopa users compared with nonusers in patients with PD. PD and PSP are associated with distinct changes in retinal morphology, which can be assessed with SD-OCT.

Effect of race, age, and axial length on optic nerve head parameters and retinal nerve fiber layer thickness measured by Cirrus HD-OCT.

PubMed

Knight, O'Rese J; Girkin, Christopher A; Budenz, Donald L; Durbin, Mary K; Feuer, William J

2012-03-01

To determine the effect of race, demographic, and ocular variables on optic nerve head and retinal nerve fiber layer (RNFL) thickness measurements using spectral-domain optical coherence tomography. In a cross-sectional observational study, 284 normal subjects aged 18 to 84 years were evaluated at 7 sites using Cirrus HD-OCT. Disc area, rim area, average cup-disc ratio, vertical cup-disc ratio, cup volume, and average, temporal, superior, nasal, and inferior RNFL thicknesses were calculated. The main outcome measures were associations between Cirrus HD-OCT optic nerve head and RNFL measurements and age, sex, and race. The 284 subjects self-identified as being of European (122), Chinese (63), African (51), or Hispanic (35) descent. After adjusting for the effect of age, there was a statistically significant difference among racial groups for all optic nerve head and RNFL parameters (all P ≤ .005) except rim area (P = .22). Rim area, average cup-disc ratio, vertical cup-disc ratio, and cup volume were moderately associated with disc area (r(2) = 0.15, 0.33, 0.33, and 0.37, respectively). After a linear adjustment for disc area, there was no statistically significant difference among racial groups for any optic nerve head parameter. Individuals of European descent had thinner RNFL measurements except in the temporal quadrant. There are racial differences in optic disc area, average cup-disc ratio, vertical cup-disc ratio, cup volume, and RNFL thickness as measured by Cirrus HD-OCT. These differences should be considered when using Cirrus HD-OCT to assess for glaucomatous damage in differing population groups.

Effect of Race, Age, and Axial Length on Optic Nerve Head Parameters and Retinal Nerve Fiber Layer Thickness Measured by Cirrus HD-OCT

PubMed Central

Knight, O’Rese J.; Girkin, Christopher A.; Budenz, Donald L.; Durbin, Mary K.; Feuer, William J.

2017-01-01

Objective To determine the effect of race, demographic, and ocular variables on optic nerve head and retinal nerve fiber layer (RNFL) thickness measurements using spectral-domain optical coherence tomography. Methods In a cross-sectional observational study, 284 normal subjects aged 18 to 84 years were evaluated at 7 sites using Cirrus HD-OCT. Disc area, rim area, average cup-disc ratio, vertical cup-disc ratio, cup volume, and average, temporal, superior, nasal, and inferior RNFL thicknesses were calculated. The main outcome measures were associations between Cirrus HD-OCT optic nerve head and RNFL measurements and age, sex, and race. Results The 284 subjects self-identified as being of European (122), Chinese (63), African (51), or Hispanic (35) descent. After adjusting for the effect of age, there was a statistically significant difference among racial groups for all optic nerve head and RNFL parameters (all P≤.005) except rim area (P=.22). Rim area, average cup-disc ratio, vertical cup-disc ratio, and cup volume were moderately associated with disc area (r2=0.15, 0.33, 0.33, and 0.37, respectively). After a linear adjustment for disc area, there was no statistically significant difference among racial groups for any optic nerve head parameter. Individuals of European descent had thinner RNFL measurements except in the temporal quadrant. Conclusions There are racial differences in optic disc area, average cup-disc ratio, vertical cup-disc ratio, cup volume, and RNFL thickness as measured by Cirrus HD-OCT. These differences should be considered when using Cirrus HD-OCT to assess for glaucomatous damage in differing population groups. PMID:22411660

Effect of cataract surgery on retinal nerve fiber layer thickness parameters using scanning laser polarimetry (GDxVCC)

PubMed Central

Dada, Tanuj; Behera, Geeta; Agarwal, Anand; Kumar, Sanjeev; Sihota, Ramanjit; Panda, Anita

2010-01-01

Purpose: To study the effect of cataract extraction on the retinal nerve fiber layer (RNFL) thickness, and assessment by scanning laser polarimetry (SLP), with variable corneal compensation (GDx VCC), at the glaucoma service of a tertiary care center in North India. Materials and Methods: Thirty-two eyes of 32 subjects were enrolled in the study. The subjects underwent RNFL analysis by SLP (GDx VCC) before undergoing phacoemulsification cataract extraction with intraocular lens (IOL) implantation (Acrysof SA 60 AT) four weeks following cataract surgery. The RNFL thickness parameters evaluated both before and after surgery included temporal, superior, nasal, inferior, temporal (TSNIT) average, superior average, inferior average, and nerve fiber index (NFI). Results: The mean age of subjects was 57.6 ± 11.7 years (18 males, 14 females). Mean TSNIT average thickness (μm) pre- and post-cataract surgery was 49.2 ± 14.1 and 56.5 ± 7.6 (P = 0.001). There was a statistically significant increase in RNFL thickness parameters (TSNIT average, superior average, and inferior average) and decrease in NFI post-cataract surgery as compared to the baseline values. Mean NFI pre- and post-cataract surgery was 41.3 ± 15.3 and 21.6 ± 11.8 (P = 0.001). Conclusions: Measurement of RNFL thickness parameters by scanning laser polarimetry is significantly altered following cataract surgery. Post the cataract surgery, a new baseline needs to be established for assessing the longitudinal follow-up of a glaucoma patient. The presence of cataract may lead to an underestimation of the RNFL thickness, and this should be taken into account when analyzing progression in a glaucoma patient. PMID:20689193

Role of Retinal Nerve Fiber Layer Thickness and Optic Disk Measurement by OCT on Early Diagnosis of Glaucoma.

PubMed

Hua, Zanmei; Fang, Qiuyun; Sha, Xiangyin; Yang, Ruiming; Hong, Zuopeng

2015-03-01

Glaucoma is an eye disease that can lead to irreversible optic nerve damage and cause blindness. Optical coherence tomography (OCT) allows an early diagnosis of glaucoma by the measurements of the retinal nerve fiber and optic disc parameters. A retrospective study was designed to analyze the effects of the measurement of the retinal nerve fiber layer (RNFL) thickness and the optic disc tomography by spectral-domain OCT on the early diagnosis of suspected glaucoma and primary open angle glaucoma (POAG). This was a clinical case-control study. The RNFL thickness around the optic disc and optic disk tomographic parameters of the control (n = 51, 98 eyes), suspected glaucoma (n = 81, 146 eyes), and POAG groups (n = 55, 106 eyes) were measured by OCT. The parameters included superior, inferior, nasal and temporal mean RNFL thickness, disc area (DA), cup area (CA), rim area (RA), disc volume (DV), cup volume (CV), rim volume (RV), cup/disc area ratio (CA/DA), rim/disc area ratio (RA/DA), cup/disc volume ratio (CV/DV) and rim/disc volume ratio (RV/DV). Superior, nasal, and mean RNFL parameters, DA, CA,RA, DV, CV, CA/DA, RA/DA, CV/DV and RV/DV significantly differed among three groups by single-factorial ANOVA. Inferior and temporal RNFL thickness significantly differed between the control and POAG groups. No significant difference was observed in RV among three groups. In the POAG group, the maximum area under the ROC curve (AROC) of mean RNFL thickness was 0.845. The maximum AROC of optic disk parameters was RA/DA (0.998), followed by CA/DA (0.997). The AROC of CA, RA, CV, and DV were all > 0.900. OCT may serve as a useful diagnostic modality in distinguishing suspected glaucoma from POAG.

High-resolution imaging of the retinal nerve fiber layer in normal eyes using adaptive optics scanning laser ophthalmoscopy.

PubMed

Takayama, Kohei; Ooto, Sotaro; Hangai, Masanori; Arakawa, Naoko; Oshima, Susumu; Shibata, Naohisa; Hanebuchi, Masaaki; Inoue, Takashi; Yoshimura, Nagahisa

2012-01-01

To conduct high-resolution imaging of the retinal nerve fiber layer (RNFL) in normal eyes using adaptive optics scanning laser ophthalmoscopy (AO-SLO). AO-SLO images were obtained in 20 normal eyes at multiple locations in the posterior polar area and a circular path with a 3-4-mm diameter around the optic disc. For each eye, images focused on the RNFL were recorded and a montage of AO-SLO images was created. AO-SLO images for all eyes showed many hyperreflective bundles in the RNFL. Hyperreflective bundles above or below the fovea were seen in an arch from the temporal periphery on either side of a horizontal dividing line to the optic disc. The dark lines among the hyperreflective bundles were narrower around the optic disc compared with those in the temporal raphe. The hyperreflective bundles corresponded with the direction of the striations on SLO red-free images. The resolution and contrast of the bundles were much higher in AO-SLO images than in red-free fundus photography or SLO red-free images. The mean hyperreflective bundle width around the optic disc had a double-humped shape; the bundles at the temporal and nasal sides of the optic disc were narrower than those above and below the optic disc (P<0.001). RNFL thickness obtained by optical coherence tomography correlated with the hyperreflective bundle widths on AO-SLO (P<0.001) AO-SLO revealed hyperreflective bundles and dark lines in the RNFL, believed to be retinal nerve fiber bundles and Müller cell septa. The widths of the nerve fiber bundles appear to be proportional to the RNFL thickness at equivalent distances from the optic disc.

Comparative data on SD-OCT for the retinal nerve fiber layer and retinal macular thickness in a large cohort with Marfan syndrome.

PubMed

Xu, WanWan; Kurup, Sudhi P; Fawzi, Amani A; Durbin, Mary K; Maumenee, Irene H; Mets, Marilyn B

2017-01-01

To report the distribution of macular and optic nerve topography in the eyes of individuals with Marfan syndrome aged 8-56 years using spectral domain optical coherence tomography (SD-OCT). Thirty-three patients with Marfan syndrome underwent a full eye examination including slit-lamp biomicroscopy, indirect ophthalmoscopy, and axial length measurement; and SD-OCT measurements of the retinal nerve fiber layer (RNFL) and macular thickness. For patients between the ages of 8 and 12 years, the average RNFL thickness is 98 ± 9 μm, the vertical cup to disc (C:D) ratio is 0.50 ± 0.10, the central subfield thickness (CST) is 274 ± 38 μm, and the macular volume is 10.3 ± 0.6 mm 3 . For patients between the ages of 13 and 17 years, the average RNFL is 86 ± 16 μm, the vertical C:D ratio is 0.35 ± 0.20, the CST is 259 ± 15 μm, and the macular volume is 10.1 ± 0.5 mm 3 . For patients 18 years or older, the average RNFL is 89 ± 12 μm, the vertical C:D ratio is 0.46 ± 0.18, the CST is 262 ± 20 μm, and the macular volume is 10.2 ± 0.4 mm 3 . When the average RNFL data are compared to a normative, age-adjusted database, 6 of 33 (18%) were thinner than the 5% limit. This study reports the distribution of SD-OCT data for patients with Marfan syndrome. Compared to a normative database, 18% of eyes with Marfan syndrome had RNFL thickness < 5% of the population.

Assessment of Optical Coherence Tomography Color Probability Codes in Myopic Glaucoma Eyes After Applying a Myopic Normative Database.

PubMed

Seol, Bo Ram; Kim, Dong Myung; Park, Ki Ho; Jeoung, Jin Wook

2017-11-01

To evaluate the optical coherence tomography (OCT) color probability codes based on a myopic normative database and to investigate whether the implementation of the myopic normative database can improve the OCT diagnostic ability in myopic glaucoma. Comparative validity study. In this study, 305 eyes (154 myopic healthy eyes and 151 myopic glaucoma eyes) were included. A myopic normative database was obtained based on myopic healthy eyes. We evaluated the agreement between OCT color probability codes after applying the built-in and myopic normative databases, respectively. Another 120 eyes (60 myopic healthy eyes and 60 myopic glaucoma eyes) were included and the diagnostic performance of OCT color codes using a myopic normative database was investigated. The mean weighted kappa (Kw) coefficients for quadrant retinal nerve fiber layer (RNFL) thickness, clock-hour RNFL thickness, and ganglion cell-inner plexiform layer (GCIPL) thickness were 0.636, 0.627, and 0.564, respectively. The myopic normative database showed a higher specificity than did the built-in normative database in quadrant RNFL thickness, clock-hour RNFL thickness, and GCIPL thickness (P < .001, P < .001, and P < .001, respectively). The receiver operating characteristic curve values increased when using the myopic normative database in quadrant RNFL thickness, clock-hour RNFL thickness, and GCIPL thickness (P = .011, P = .004, P < .001, respectively). The diagnostic ability of OCT color codes for detection of myopic glaucoma significantly improved after application of the myopic normative database. The implementation of a myopic normative database is needed to allow more precise interpretation of OCT color probability codes when used in myopic eyes. Copyright © 2017 Elsevier Inc. All rights reserved.

Differences in Optic Nerve Head, Retinal Nerve Fiber Layer, and Ganglion Cell Complex Parameters Between Caucasian and Chinese Subjects.

PubMed

Chansangpetch, Sunee; Huang, Guofu; Coh, Paul; Oldenburg, Catherine; Amoozgar, Behzad; He, Mingguang; Lin, Shan C

2018-04-01

To compare optic nerve head, peripapillary retinal nerve fiber layer (pRNFL), and ganglion cell complex (GCC) parameters between Caucasian and ethnic Chinese. Normal subjects above 40 years old and self-identified as being Caucasian and Chinese were recruited. They were evaluated with spectral-domain optical coherence tomography (RTVue-100). Parameters related to the optic nerve head, pRNFL, and GCC analysis protocols were acquired. Multivariable linear regression was performed adjusting for potential confounders. Data from 116 Caucasian and 130 Chinese subjects were available for analysis. Mean age of all participants was 66.72 (SD 10.82) years. There were statistically significant differences for disc area (DA), area cup-to-disc, vertical cup-to-disc, and cup volume (P=0.02, 0.004, 0.02, and 0.03, respectively), greater in Chinese. After adjusting for age, sex, axial length (AL), intraocular pressure (IOP), DA, and GCC thickness, Chinese subjects had significantly greater thickness in all pRNFL parameters (mean differences ranged between 4.29 and 9.93 μm; all P<0.001) except the nasal quadrant. GCC outcomes were also adjusted for DA and pRNFL; Caucasians had significantly higher average GCC and inferior GCC (mean difference 2.97 and 3.45 μm, respectively; P<0.01), whereas the Chinese group had significantly higher ganglion cell global loss volume (mean difference 2.47 %, P<0.001). This study suggests there is significantly greater pRNFL thickness in Chinese, which were independent of age, AL, IOP, and DA, and possibly greater GCC in Caucasians after adjustment for age, AL, IOP, DA, and pRNFL thickness.

Macular versus Retinal Nerve Fiber Layer Parameters for Diagnosing Manifest Glaucoma: A Systematic Review of Diagnostic Accuracy Studies.

PubMed

Oddone, Francesco; Lucenteforte, Ersilia; Michelessi, Manuele; Rizzo, Stanislao; Donati, Simone; Parravano, Mariacristina; Virgili, Gianni

2016-05-01

Macular parameters have been proposed as an alternative to retinal nerve fiber layer (RNFL) parameters to diagnose glaucoma. Comparing the diagnostic accuracy of macular parameters, specifically the ganglion cell complex (GCC) and ganglion cell inner plexiform layer (GCIPL), with the accuracy of RNFL parameters for detecting manifest glaucoma is important to guide clinical practice and future research. Studies using spectral domain optical coherence tomography (SD OCT) and reporting macular parameters were included if they allowed the extraction of accuracy data for diagnosing manifest glaucoma, as confirmed with automated perimetry or a clinician's optic nerve head (ONH) assessment. Cross-sectional cohort studies and case-control studies were included. The QUADAS 2 tool was used to assess methodological quality. Only direct comparisons of macular versus RNFL parameters (i.e., in the same study) were conducted. Summary sensitivity and specificity of each macular or RNFL parameter were reported, and the relative diagnostic odds ratio (DOR) was calculated in hierarchical summary receiver operating characteristic (HSROC) models to compare them. Thirty-four studies investigated macular parameters using RTVue OCT (Optovue Inc., Fremont, CA) (19 studies, 3094 subjects), Cirrus OCT (Carl Zeiss Meditec Inc., Dublin, CA) (14 studies, 2164 subjects), or 3D Topcon OCT (Topcon, Inc., Tokyo, Japan) (4 studies, 522 subjects). Thirty-two of these studies allowed comparisons between macular and RNFL parameters. Studies generally reported sensitivities at fixed specificities, more commonly 0.90 or 0.95, with sensitivities of most best-performing parameters between 0.65 and 0.75. For all OCT devices, compared with RNFL parameters, macular parameters were similarly or slightly less accurate for detecting glaucoma at the highest reported specificity, which was confirmed in analyses at the lowest specificity. Included studies suffered from limitations, especially the case-control study design, which is known to overestimate accuracy. However, this flaw is less relevant as a source of bias in direct comparisons conducted within studies. With the use of OCT, RNFL parameters are still preferable to macular parameters for diagnosing manifest glaucoma, but the differences are small. Because of high heterogeneity, direct comparative or randomized studies of OCT devices or OCT parameters and diagnostic strategies are essential. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Scanning laser polarimetry, but not optical coherence tomography predicts permanent visual field loss in acute nonarteritic anterior ischemic optic neuropathy.

PubMed

Kupersmith, Mark J; Anderson, Susan; Durbin, Mary; Kardon, Randy

2013-08-15

Scanning laser polarimetry (SLP) reveals abnormal retardance of birefringence in locations of the edematous peripapillary retinal nerve fiber layer (RNFL), which appear thickened by optical coherence tomography (OCT), in nonarteritic anterior ischemic optic neuropathy (NAION). We hypothesize initial sector SLP RNFL abnormalities will correlate with long-term regional visual field loss due to ischemic injury. We prospectively performed automated perimetry, SLP, and high definition OCT (HD-OCT) of the RNFL in 25 eyes with acute NAION. We grouped visual field threshold and RNFL values into Garway-Heath inferior/superior disc sectors and corresponding superior/inferior field regions. We compared sector SLP RNFL thickness with corresponding visual field values at presentation and at >3 months. At presentation, 12 eyes had superior sector SLP reduction, 11 of which had inferior field loss. Six eyes, all with superior field loss, had inferior sector SLP reduction. No eyes had reduced OCT-derived RNFL acutely. Eyes with abnormal field regions had corresponding SLP sectors thinner (P = 0.003) than for sectors with normal field regions. During the acute phase, the SLP-derived sector correlated with presentation (r = 0.59, P = 0.02) and with >3-month after presentation (r = 0.44, P = 0.02) corresponding superior and inferior field thresholds. Abnormal RNFL birefringence occurs in sectors corresponding to regional visual field loss during acute NAION when OCT-derived RNFL shows thickening. Since the visual field deficits show no significant recovery, SLP can be an early marker for axonal injury, which may be used to assess recovery potential at RNFL locations with respect to new treatments for acute NAION.

Evaluation of spectral domain optical coherence tomography parameters in ocular hypertension, preperimetric, and early glaucoma.

PubMed

Aydogan, Tuğba; Akçay, BetÜl İlkay Sezgin; Kardeş, Esra; Ergin, Ahmet

2017-11-01

The objective of this study is to evaluate the diagnostic ability of retinal nerve fiber layer (RNFL), macular, optic nerve head (ONH) parameters in healthy subjects, ocular hypertension (OHT), preperimetric glaucoma (PPG), and early glaucoma (EG) patients, to reveal factors affecting the diagnostic ability of spectral domain-optical coherence tomography (SD-OCT) parameters and risk factors for glaucoma. Three hundred and twenty-six eyes (89 healthy, 77 OHT, 94 PPG, and 66 EG eyes) were analyzed. RNFL, macular, and ONH parameters were measured with SD-OCT. The area under the receiver operating characteristic curve (AUC) and sensitivity at 95% specificity was calculated. Logistic regression analysis was used to determine the glaucoma risk factors. Receiver operating characteristic regression analysis was used to evaluate the influence of covariates on the diagnostic ability of parameters. In PPG patients, parameters that had the largest AUC value were average RNFL thickness (0.83) and rim volume (0.83). In EG patients, parameter that had the largest AUC value was average RNFL thickness (0.98). The logistic regression analysis showed average RNFL thickness was a risk factor for both PPG and EG. Diagnostic ability of average RNFL and average ganglion cell complex thickness increased as disease severity increased. Signal strength index did not affect diagnostic abilities. Diagnostic ability of average RNFL and rim area increased as disc area increased. When evaluating patients with glaucoma, patients at risk for glaucoma, and healthy controls RNFL parameters deserve more attention in clinical practice. Further studies are needed to fully understand the influence of covariates on the diagnostic ability of OCT parameters.

Scanning laser polarimetry in glaucoma

PubMed Central

Dada, Tanuj; Sharma, Reetika; Angmo, Dewang; Sinha, Gautam; Bhartiya, Shibal; Mishra, Sanjay K; Panda, Anita; Sihota, Ramanjit

2014-01-01

Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far. PMID:25494244

Scanning laser polarimetry in glaucoma.

PubMed

Dada, Tanuj; Sharma, Reetika; Angmo, Dewang; Sinha, Gautam; Bhartiya, Shibal; Mishra, Sanjay K; Panda, Anita; Sihota, Ramanjit

2014-11-01

Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.

Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure.

PubMed

Wei, Yantao; Jiang, Hong; Shi, Yingying; Qu, Dongyi; Gregori, Giovanni; Zheng, Fang; Rundek, Tatjana; Wang, Jianhua

2017-07-01

To characterize age-related alterations in the retinal microcirculation, microvascular network, and microstructure in healthy subjects. Seventy-four healthy subjects aged from 18 to 82 years were recruited and divided into four age groups (G1 with age <35 years, G2 with age 35 ∼ 49 years, G3 with age 50 ∼ 64 years, and G4 with age ≥65 years). Custom ultra-high resolution optical coherence tomography (UHR-OCT) was used to acquire six intraretinal layers of the macula. OCT angiography (OCTA) was used to image the retinal microvascular network. The retinal blood flow velocity (BFV) was measured using a Retinal Function Imager (RFI). Compared to G1, G2 had significant thinning of the retinal nerve fiber layer (RNFL) (P < 0.05), while G3 had thinning of the RNFL and ganglion cell and inner plexiform layer (GCIPL) (P < 0.05), in addition to thickening of the outer plexiform layer (OPL) and photoreceptor layer (PR) (P < 0.05). G4 had loss in retinal vessel density, thinning in RNFL and GCIPL, and decrease in venular BFV, in addition to thickening of the OPL and PR (P < 0.05). Age was negatively related to retinal vessel densities, the inner retinal layers, and venular BFV (P < 0.05). By contrast, age was positively related to OPL and PR (P < 0.05). During aging, decreases in retinal vessel density, inner retinal layer thickness, and venular BFV were evident and impacted each other as observed by simultaneous changes in multiple retinal components.

Evaluation of white matter hyperintensities and retinal fiber layer, ganglion cell layer, inner-plexiform layer, and choroidal layer in migraine patients.

PubMed

Tak, Ali Zeynel Abidin; Sengul, Yıldızhan; Bilak, Şemsettin

2018-03-01

The aim of our study is to assess retinal nerve fiber layer (RNFL), the ganglion cell layer (GCL), inner-plexiform layer (IPL), and choroidal layer in migraine patients with white matter lesion (WML) or without WML, using spectral domain optical coherence tomography (OCT). To our study, 77 migraine patients who are diagnosed with migraine in accordance to the International Classification of Headache Disorders (ICHD)-3 beta and 43 healthy control are included. In accordance to cranial MRI, migraine patients are divided into two groups as those who have white matter lesions (39 patients), and those who do not have a lesion (38 patients). OCT was performed for participants. The average age of participants was comparable. The RNFL average thickness parameter in the migraine group was significantly lower than in the control group (p < 0.01). However, no significant difference was detected among those migraine patients who have WML, and those who do not have. No significant difference is detected among all groups in terms of IPL, GCL, and choroidal layer measuring scales. The proofs showing that affected retinal nerve fiber layer are increased in migraine patients. However, it is not known whether this may affect other layers of retina, or whether there is a correlation between affected retinal structures and white matter lesions. In our study, we found thinner RNFL in migraine patients when we compared with controls but IPL, GCL, and choroid layer values were similar between each patient groups and controls. Also, all parameters were similar between patients with WML and without WML. Studies in this regard are required.

Retinal degeneration in progressive supranuclear palsy measured by optical coherence tomography and scanning laser polarimetry.

PubMed

Stemplewitz, Birthe; Kromer, Robert; Vettorazzi, Eik; Hidding, Ute; Frings, Andreas; Buhmann, Carsten

2017-07-13

This cross-sectional study compared the retinal morphology between patients with progressive supranuclear palsy (PSP) and healthy controls. (The retinal nerve fiber layer (RNFL) around the optic disc and the retina in the macular area of 22 PSP patients and 151 controls were investigated by spectral domain optical coherence tomography (SD-OCT). Additionally, the RNFL and the nerve fiber index (NFI) were measured by scanning laser polarimetry (SLP). Results of RNFL measurements with SD-OCT and SLP were compared to assess diagnostic discriminatory power. Applying OCT, PSP patients showed a smaller RNFL thickness in the inferior nasal and inferior temporal areas. The macular volume and the thickness of the majority of macular sectors were reduced compared to controls. SLP data showed a thinner RNFL thickness and an increase in the NFI in PSP patients. Sensitivity and specificity to discriminate PSP patients from controls were higher applying SLP than SD-OCT. Retinal changes did not correlate with disease duration or severity in any OCT or SLP measurement. PSP seems to be associated with reduced thickness and volume of the macula and reduction of the RNFL, independent of disease duration or severity. Retinal imaging with SD-OCT and SLP might become an additional tool in PSP diagnosis.

Peripapillary Retinal Nerve Fiber Layer Vascular Microcirculation in Eyes With Glaucoma and Single-Hemifield Visual Field Loss.

PubMed

Chen, Chieh-Li; Bojikian, Karine D; Wen, Joanne C; Zhang, Qinqin; Xin, Chen; Mudumbai, Raghu C; Johnstone, Murray A; Chen, Philip P; Wang, Ruikang K

2017-05-01

Understanding the differences in vascular microcirculation of the peripapillary retinal nerve fiber layer (RNFL) between the hemispheres in eyes with glaucoma with single-hemifield visual field (VF) defects may provide insight into the pathophysiology of glaucoma. To investigate the changes in the microcirculation of the peripapillary RNFL of eyes with glaucoma by using optical microangiography. Eyes with glaucoma and single-hemifield VF defect and normal eyes underwent scanning using an optical microangiography system covering a 6.7 × 6.7-mm2 area centered at the optic nerve head. The RNFL microcirculation was measured within an annulus region centered at the optic nerve head divided into superior and inferior hemispheres. Blood flux index (the mean flow signal intensity in the vessels) and vessel area density (the percentage of the detected vessels in the annulus) were measured. Differences in microcirculation between the hemispheres in eyes with glaucoma and normal eyes and correlations among blood flow metrics, VF thresholds, and clinical optical coherence tomography structural measurements were assessed. Twenty-one eyes from 21 patients with glaucoma (7 men and 14 women; mean [SD] age, 63.7 [9.9] years) and 20 eyes from 20 healthy control individuals (9 men and 11 women; mean [SD] age, 68.3 [10.7] years) were studied. In eyes with glaucoma, the abnormal hemisphere showed a thinner RNFL (mean [SE] difference, 23.5 [4.5] μm; 95% CI, 15.1-32.0 µm; P < .001), lower RNFL blood flux index (mean [SE] difference, 0.04 [0.01]; 95% CI, 0.02-0.05; P < .001), and less vessel area density (mean [SE] difference, 0.08% [0.02%]; 95% CI, 0.05%-0.10%; P < .001) than did the normal hemisphere. Compared with normal eyes, reduced RNFL microcirculation was found in the normal hemisphere of eyes with glaucoma, measured by mean [SE] differences in blood flux index (0.06 [0.01]; 95% CI, 0.04-0.09; P < .001) and vessel area density (0.04% [0.02%]; 95% CI, 0.02%-0.08%; P = .003) but not in RNFL thickness (3.4 [4.7] μm; 95% CI, -6.2 to 12.9 µm; P = .48). Strong correlations were found between the blood flux index and VF mean deviation (Spearman ρ = 0.44; P = .045) and RNFL thickness (Spearman ρ = 0.65; P = .001) in the normal hemisphere of the eye with glaucoma. Reduced RNFL microcirculation was detected in the normal hemisphere of eyes with glaucoma, with strong correspondence with VF loss and RNFL thinning. Although the results suggest that vascular dysfunction precedes structural changes seen in glaucoma, longitudinal studies would be needed to confirm this finding.

Change of Retinal Nerve Layer Thickness in Non-Arteritic Anterior Ischemic Optic Neuropathy Revealed by Fourier Domain Optical Coherence Tomography.

PubMed

Han, Mei; Zhao, Chen; Han, Quan-Hong; Xie, Shiyong; Li, Yan

2016-08-01

To examine the changes of non-arteritic anterior ischemic optic neuropathy (NAION) by serial morphometry using Fourier domain optical coherence tomography (FD-OCT). Retrospective study in patients with newly diagnosed NAION (n=33, all unilateral) and controls (n=75 unilateral NAION patients with full contralateral eye vision) who underwent FD-OCT of the optic disk, optic nerve head (ONH), and macula within 1 week of onset and again 1, 3, 6, and 12 months later. The patients showed no improvement in vision during follow-up. Within 1 week of onset, all NAION eyes exhibited severe ONH fiber crowding and peripapillary retinal nerve fiber layer (RNFL) edema. Four had subretinal fluid accumulation and 12 had posterior vitreous detachment (PVD) at the optic disc surface. Ganglion cell complex (GCC) and RNFL thicknesses were reduced at 1 and 3 months (p < 0.05), with no deterioration thereafter. Initial RNFL/GCC contraction magnitude in the superior hemisphere correlated with the severity of inferior visual field deficits. NAION progression is characterized by an initial phase of accelerated RNFL and GCC deterioration. These results reveal that the kinetic change of neural retina in NAION and may have implication on the time window for treatment of NAION. FD-OCT is useful in the evaluation of NAION.

Study of long term structural and functional changes in medically controlled glaucoma

PubMed Central

Pandey, Achyut N; Sujata, S

2014-01-01

AIM Prospectively analyze the long term structural and functional changes in patients of primary open angle glaucoma (POAG) receiving medical therapy (beta blockers and non beta blockers). In this study an attempt has been made to evaluate whether medical reduction of IOP prevents or delays the progression of glaucomatous visual field loss and/or optic nerve damage in patients with open angle glaucoma. METHODS Study conducted over a period of 27 months, at a tertiary eye care hospital including both eyes of 40 patients with POAG. Group 1 (20 patients, 40 eyes) received beta-blockers, and Group 2 (20 patients, 40 eyes) received non-beta-blockers. Each patient underwent intraocular pressure measurement, best corrected visual acuity, slit-lamp, fundus examination, gonioscopy, central corneal thickness, visual field assessment by Humphrey automated perimetry and retinal nerve fibre layer thickness by Stratus optical coherence tomography at baseline and at two subsequent visits. The average time interval between each visit was 10-11 months. The statistical analysis was done using one-way analysis of variance (ANOVA). Post-hoc test, using tukey' method were adopted. Probablity (P) value of 0.05 or less was considered to be statistically significant. RESULTS A total of 80 eyes of 40 patients of POAG were enrolled, 24 males, 16 females, age group 50-80 years. In both beta and non beta blocker group, reduction (improvement) in mean IOP from initial levels to the levels achieved at the 2nd and 3rd visits was statistically significant. One way ANOVA (df=2), fisher f value=11.64, P=0.000, one way ANOVA (df=3), fisher f value=35.61, P=0.000. Both mean deviation (MD) and pattern standard deviation (PSD) in both beta and non beta blockers at different visits were not statistically significant. Retinal nerve fibre layer thickness (RNFL) -only mean inferior retinal nerve fibre layer, the difference between the mean value in beta and non beta blocker groupwere statistically significant. [unpaired t test value (df=78) =2.27, P=0.03]. Side effects with beta blocker were conjunctival hyperemia (10%), burning (5%), and conjunctival hyperemia (5%) in non beta blockers. CONCLUSION Non-beta-blockers are as effective as beta-blockers in bringing about a significant lowering of intraocular pressure to the normal range, and in preventing progressive damage to the visual fields and retinal nerve fibre layer. The absence of systemic side effects and superior IOP lowering efficacy has made non beta-blockers attractive for first line therapy for the treatment of glaucoma worldwide. PMID:24634878

Study of long term structural and functional changes in medically controlled glaucoma.

PubMed

Pandey, Achyut N; Sujata, S

2014-01-01

Prospectively analyze the long term structural and functional changes in patients of primary open angle glaucoma (POAG) receiving medical therapy (beta blockers and non beta blockers). In this study an attempt has been made to evaluate whether medical reduction of IOP prevents or delays the progression of glaucomatous visual field loss and/or optic nerve damage in patients with open angle glaucoma. Study conducted over a period of 27 months, at a tertiary eye care hospital including both eyes of 40 patients with POAG. Group 1 (20 patients, 40 eyes) received beta-blockers, and Group 2 (20 patients, 40 eyes) received non-beta-blockers. Each patient underwent intraocular pressure measurement, best corrected visual acuity, slit-lamp, fundus examination, gonioscopy, central corneal thickness, visual field assessment by Humphrey automated perimetry and retinal nerve fibre layer thickness by Stratus optical coherence tomography at baseline and at two subsequent visits. The average time interval between each visit was 10-11 months. The statistical analysis was done using one-way analysis of variance (ANOVA). Post-hoc test, using tukey' method were adopted. Probablity (P) value of 0.05 or less was considered to be statistically significant. A total of 80 eyes of 40 patients of POAG were enrolled, 24 males, 16 females, age group 50-80 years. In both beta and non beta blocker group, reduction (improvement) in mean IOP from initial levels to the levels achieved at the 2nd and 3rd visits was statistically significant. One way ANOVA (df=2), fisher f value=11.64, P=0.000, one way ANOVA (df=3), fisher f value=35.61, P=0.000. Both mean deviation (MD) and pattern standard deviation (PSD) in both beta and non beta blockers at different visits were not statistically significant. Retinal nerve fibre layer thickness (RNFL) -only mean inferior retinal nerve fibre layer, the difference between the mean value in beta and non beta blocker groupwere statistically significant. [unpaired t test value (df=78) =2.27, P=0.03]. Side effects with beta blocker were conjunctival hyperemia (10%), burning (5%), and conjunctival hyperemia (5%) in non beta blockers. Non-beta-blockers are as effective as beta-blockers in bringing about a significant lowering of intraocular pressure to the normal range, and in preventing progressive damage to the visual fields and retinal nerve fibre layer. The absence of systemic side effects and superior IOP lowering efficacy has made non beta-blockers attractive for first line therapy for the treatment of glaucoma worldwide.

Likelihood Ratios for Glaucoma Diagnosis Using Spectral Domain Optical Coherence Tomography

PubMed Central

Lisboa, Renato; Mansouri, Kaweh; Zangwill, Linda M.; Weinreb, Robert N.; Medeiros, Felipe A.

2014-01-01

Purpose To present a methodology for calculating likelihood ratios for glaucoma diagnosis for continuous retinal nerve fiber layer (RNFL) thickness measurements from spectral domain optical coherence tomography (spectral-domain OCT). Design Observational cohort study. Methods 262 eyes of 187 patients with glaucoma and 190 eyes of 100 control subjects were included in the study. Subjects were recruited from the Diagnostic Innovations Glaucoma Study. Eyes with preperimetric and perimetric glaucomatous damage were included in the glaucoma group. The control group was composed of healthy eyes with normal visual fields from subjects recruited from the general population. All eyes underwent RNFL imaging with Spectralis spectral-domain OCT. Likelihood ratios for glaucoma diagnosis were estimated for specific global RNFL thickness measurements using a methodology based on estimating the tangents to the Receiver Operating Characteristic (ROC) curve. Results Likelihood ratios could be determined for continuous values of average RNFL thickness. Average RNFL thickness values lower than 86μm were associated with positive LRs, i.e., LRs greater than 1; whereas RNFL thickness values higher than 86μm were associated with negative LRs, i.e., LRs smaller than 1. A modified Fagan nomogram was provided to assist calculation of post-test probability of disease from the calculated likelihood ratios and pretest probability of disease. Conclusion The methodology allowed calculation of likelihood ratios for specific RNFL thickness values. By avoiding arbitrary categorization of test results, it potentially allows for an improved integration of test results into diagnostic clinical decision-making. PMID:23972303

Natural history of Leber's hereditary optic neuropathy: longitudinal analysis of the retinal nerve fiber layer by optical coherence tomography.

PubMed

Barboni, Piero; Carbonelli, Michele; Savini, Giacomo; Ramos, Carolina do V F; Carta, Arturo; Berezovsky, Adriana; Salomao, Solange R; Carelli, Valerio; Sadun, Alfredo A

2010-03-01

To investigate by optical coherence tomography (OCT) the topographic pattern and temporal sequence of fiber loss in the peripapillary retinal nerve fiber layer (RNFL) of patients with Leber's hereditary optic neuropathy (LHON) in a longitudinal follow-up. Cohort study. Six eyes of 4 patients with molecularly defined LHON were enrolled before the subacute period of visual loss. Subjects were studied by StratusOCT (Carl Zeiss Meditec, Inc., Dublin, CA) during a 9-month follow-up starting from the presymptomatic stage of the disease. Examinations were carried out at 4 different time points: presymptomatic stage, time of visual loss, and 3 and 9 months later. Peripapillary RNFL thickness for each quadrant of the optic nerve. Statistical comparisons were performed by ordinary analysis of variance with Dunnett's post-test. A significant increase of RNFL thickness was detected in the temporal and inferior quadrants between the presymptomatic stage and the disease onset (P<0.05). The 360-degree average and the superior and nasal quadrants showed a nonstatistically significant increase of thickness at this time. In the 360-degree average (P<0.01), superior (P<0.01), nasal (P<0.05), and inferior (P<0.01) quadrants, RNFL thickening showed statistically significant changes between the presymptomatic stage and the 3-month follow-up. At 3 months, a nonsignificant reduction of RNFL thickness was detected in the temporal quadrant. A significant reduction of RNFL was detected in all but the nasal quadrants between the presymptomatic stage and the 9-month Follow-up. The RNFL thickness increase first appeared at the temporal and inferior quadrants. Conversely, at 3 months the thickening fibers were more evident in the superior and nasal quadrants. These findings are consistent with the established preferential early involvement of the papillomacular bundle in LHON. We also demonstrated the previously unrecognized simultaneous early involvement of the inferior quadrant. The late involvement of both superior and nasal quadrants suggests a dynamic evolution of the acute stage that continues for 3 months and may represent a therapeutic window of opportunity. Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Retinal nerve fiber layer analysis with scanning laser polarimetry and RTVue-OCT in patients of retinitis pigmentosa.

PubMed

Xue, Kang; Wang, Min; Chen, Junyi; Huang, Xin; Xu, Gezhi

2013-01-01

To measure the thickness of the retinal nerve fiber layer (RNFL) of patients with retinitis pigmentosa (RP) and that of normal controls by scanning laser polarimetry with enhanced corneal compensation (GDxECC) and RTVue-optical coherence tomography (OCT). Fifty-two eyes of 26 patients were included. All patients underwent complete ophthalmological examinations and testing with GDxECC. Twenty-eight of 52 eyes of RP patients underwent RTVue-OCT measurements. A group of 50 eyes of 25 normal subjects (controls) was also included. GDxECC measured RNFL thickness in the peripapillary area in all subjects as well as temporal-superior-nasal-inferior-temporal (TSNIT) parameters, including TSNIT means, superior and inferior region means, TSNIT standard deviation (SD), inter-eye symmetry and nerve fiber indicator (NFI). RTVue-OCT measured the mean, superior, inferior, temporal and nasal quadrant RNFL thickness. In RP patients and controls, TSNIT means by GDxECC were, respectively, 65.00 ± 7.35 and 55.32 ± 5.20. Mean superior quadrant thicknesses were 80.56 ± 10.93 and 69.54 ± 7.45. Mean inferior thicknesses were 80.58 ± 9.34 and 69.12 ± 7.78. SDs were 27.92 ± 5.21 and 28.23 ± 4.01. Inter-eye symmetries were 0.82 ± 0.17 and 0.87 ± 0.09. NFIs were 9.74 ± 8.73 and 16.81 ± 8.13. The differences between mean TSNIT, mean superior and mean inferior quadrant thicknesses and NFIs were statistically significant (p < 0.001). In RTVue-OCT measurements, the differences between mean, superior, inferior and temporal quadrant RNFL thicknesses were statistically significant (p = 0.0322, 0.0213, 0.0387, 0.0005). The RNFL measured by GDxECC was significantly thicker in RP patients than in controls. RNFL thickness measured by RTVue-OCT was significantly greater in RP patients than in controls in the superior, inferior and temporal regions. This contribution provides information on RNFL thickness and discusses the mechanism underlying this phenomenon. Copyright © 2012 S. Karger AG, Basel.

Macular ganglion cell imaging study: glaucoma diagnostic accuracy of spectral-domain optical coherence tomography.

PubMed

Jeoung, Jin Wook; Choi, Yun Jeong; Park, Ki Ho; Kim, Dong Myung

2013-07-01

We evaluated the diagnostic accuracy of macular ganglion cell-inner plexiform layer (GCIPL) measurements using a high-definition optical coherence tomography (Cirrus HD-OCT) ganglion cell analysis algorithm for detecting early and moderate-to-severe glaucoma. Totals of 119 normal subjects and 306 glaucoma patients (164 patients with early glaucoma and 142 with moderate-to-severe glaucoma) were enrolled from the Macular Ganglion Cell Imaging Study. Macular GCIPL, peripapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters were measured in each subject. Areas under the receiver operating characteristic curves (AUROCs) were calculated and compared. Based on the internal normative database, the sensitivity and specificity for detecting early and moderate-to-severe glaucoma were calculated. There was no statistically significant difference between the AUROCs for the best OCT parameters. For detecting early glaucoma, the sensitivity of the Cirrus GCIPL parameters ranged from 26.8% to 73.2% and that of the Cirrus RNFL parameters ranged from 6.1% to 61.6%. For the early glaucoma group, the best parameter from the GCIPL generally had a higher sensitivity than those of the RNFL and ONH parameters with comparable specificity (P < 0.05, McNemar's test). There were no significant differences between the AUROCs for Cirrus GCIPL, RNFL, and ONH parameters, indicating that these maps have similar diagnostic potentials for glaucoma. The minimum GCIPL showed better glaucoma diagnostic performance than the other parameters at comparable specificities. However, other GCIPL parameters showed performances comparable to those of the RNFL parameters.

Evaluation of spectral domain optical coherence tomography parameters in ocular hypertension, preperimetric, and early glaucoma

PubMed Central

Aydoğan, Tuğba; Akçay, Betül İlkay Sezgin; Kardeş, Esra; Ergin, Ahmet

2017-01-01

Purpose: The objective of this study is to evaluate the diagnostic ability of retinal nerve fiber layer (RNFL), macular, optic nerve head (ONH) parameters in healthy subjects, ocular hypertension (OHT), preperimetric glaucoma (PPG), and early glaucoma (EG) patients, to reveal factors affecting the diagnostic ability of spectral domain-optical coherence tomography (SD-OCT) parameters and risk factors for glaucoma. Methods: Three hundred and twenty-six eyes (89 healthy, 77 OHT, 94 PPG, and 66 EG eyes) were analyzed. RNFL, macular, and ONH parameters were measured with SD-OCT. The area under the receiver operating characteristic curve (AUC) and sensitivity at 95% specificity was calculated. Logistic regression analysis was used to determine the glaucoma risk factors. Receiver operating characteristic regression analysis was used to evaluate the influence of covariates on the diagnostic ability of parameters. Results: In PPG patients, parameters that had the largest AUC value were average RNFL thickness (0.83) and rim volume (0.83). In EG patients, parameter that had the largest AUC value was average RNFL thickness (0.98). The logistic regression analysis showed average RNFL thickness was a risk factor for both PPG and EG. Diagnostic ability of average RNFL and average ganglion cell complex thickness increased as disease severity increased. Signal strength index did not affect diagnostic abilities. Diagnostic ability of average RNFL and rim area increased as disc area increased. Conclusion: When evaluating patients with glaucoma, patients at risk for glaucoma, and healthy controls RNFL parameters deserve more attention in clinical practice. Further studies are needed to fully understand the influence of covariates on the diagnostic ability of OCT parameters. PMID:29133640

Diagnostic Consistency and Relation Between Optical Coherence Tomography and Standard Automated Perimetry in Primary Open-Angle Glaucoma.

PubMed

Toprak, Ibrahim; Yaylalı, Volkan; Yildirim, Cem

2017-01-01

To assess diagnostic consistency and relation between spectral-domain optical coherence tomography (SD-OCT) and standard automated perimetry (SAP) in patients with primary open-angle glaucoma (POAG). This retrospective study comprised 51 eyes of 51 patients with a confirmed diagnosis of POAG. The qualitative and quantitative SD-OCT parameters (retinal nerve fiber layer thicknesses [RNFL; average, superior, inferior, nasal and temporal], RNFL symmetry, rim area, disc area, average and vertical cup/disc [C/D] ratio and cup volume) were compared with parameters of SAP (mean deviation, pattern standard deviation, visual field index, and glaucoma hemifield test reports). Fifty-one eyes of 51 patients with POAG were recruited. Twenty-nine eyes (56.9%) had consistent RNFL and visual field (VF) damage. However, nine patients (17.6%) showed isolated RNFL damage on SD-OCT and 13 patients (25.5%) had abnormal VF test with normal RNFL. In patients with VF defect, age, average C/D ratio, vertical C/D ratio, and cup volume were significantly higher and rim area was lower when compared to those of the patients with normal VF. In addition to these parameters, worsening in average, superior, inferior, and temporal RNFL thicknesses and RNFL symmetry was significantly associated with consistent SD-OCT and SAP outcomes. In routine practice, patients with POAG can be manifested with inconsistent reports between SD-OCT and SAP. An older age, higher C/D ratio, larger cup volume, and lower rim area on SD-OCT appears to be associated with detectable VF damage. Moreover, additional worsening in RNFL parameters might reinforce diagnostic consistency between SD-OCT and SAP.

Cupping reversal in pediatric glaucoma--evaluation of the retinal nerve fiber layer and visual field.

PubMed

Ely, Amanda L; El-Dairi, Mays A; Freedman, Sharon F

2014-11-01

To identify optic nerve head (ONH) cupping reversal and associated optical coherence tomography (OCT) and Humphrey visual field changes in pediatric glaucoma. Retrospective observational case series. Sequential surgical cases of juvenile open-angle glaucoma (OAG) or primary congenital glaucoma (PCG) with sustained postoperative intraocular pressure (IOP) reduction. Group 1 had preoperative and postoperative ONH photographs and OCT; Group 2 had preoperative clinical ONH assessment and postoperative imaging. Cupping evaluation was confirmed by masked glaucoma and neuro-ophthalmology specialists. Of 80 cases, 9 eyes (9 children) met criteria for Group 1; 24 eyes (19 children) met criteria for Group 2. Group 1: Five of 9 eyes (56%) demonstrated cupping reversal, with preoperative vs postoperative mean IOP 34.2 ± 6.6 mm Hg vs 10.6 ± 4.1 mm Hg (P < .00001) and mean average retinal nerve fiber layer (RNFL) 71.0 ± 30 μm vs 62.8 ± 24 μm (P = .4), respectively. RNFL was stable in 4 of 5 eyes (all juvenile OAG), but thinned (Δ = -41 μm) in 1 eye with PCG. Humphrey visual fields (reliable in 2 of 3 eyes) showed no significant change. Group 2: Fourteen of 24 PCG eyes (58%) demonstrated cupping reversal, with preoperative vs postoperative mean IOP 36.1 ± 8.9 mm Hg vs 13.3 ± 2.1 mm Hg (P < .00001). Two eyes had thin RNFL postoperatively despite healthy-appearing ONH. Postoperative RNFL showed statistically significant linear correlation with preoperative (but not postoperative) cup-to-disc ratio. Limitations include small numbers, few reliable Humphrey visual fields, and absent preoperative imaging (Group 2). Some eyes with IOP reduction and ONH cupping reversal show continued RNFL thinning postoperatively. The preoperative ONH cup-to-disc ratio predicted the postoperative RNFL better than the postoperative "reversed and smaller" cup-to-disc ratio. Cupping reversal in pediatric glaucoma may not predict improved ONH health and deserves further study. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of multiple intravitreal anti-VEGF injections on retinal nerve fiber layer and intraocular pressure: a comparative clinical study

PubMed Central

Sobacı, Güngör; Güngör, Rıza; Özge, Gökhan

2013-01-01

AIM To determine the effect of multiple injections of ranibizumab or bevacizumab on retinal nerve fiber layer (RNFL) and intraocular pressure (IOP) in patients with age-related macular degeneration (AMD). METHODS This retrospective study includes 35 eyes of 35 patients treated with intravitreal bevacizumab (IVB, 1.25mg/0.05mL) and 30 eyes of 30 patients with intravitreal ranibizumab (IVR, 0.5mg/0.05mL) who had Fast RNFL analysis (Stratus™); IOP measurements were taken 30 minutes and 24 hours after each injection. RESULTS The mean ages were 68.0±7.5 and 69.1±7.7 years in the IVR and IVB groups, respectively (P=0.55). They underwent (6.3±1.9) and (5.1±1.3) injections (P=0.07) over (13.6±2.1) and (14.05±2.6) months (P=0.45) in the IVR and IVB groups, respectively. Changes in overall and temporal RNFL thickness in IVR-treated eyes (105.3±6.9µm and 74.4±11.2µm) were not different from those in untreated eyes in the IVR group (104.6± 8.4µm and 75.1±12.6µm) (P=0.57 and P=0.41, respectively). Similarly, overall and temporal RNFL thickness in IVB-treated eyes (105.8±8.1µm and 74.5±11.8µm) were not different from those in untreated eyes in the IVB group (104.6±8µm and 74.8±12.9µm) (P=0.42 and P=0.80, respectively). The frequencies of IOP rise (P=0.60) and changes in RNFL thickness from baseline (P=0.16) were comparable between groups. CONCLUSION Repeated intravitreal injection of ranibizumab or bevacizumab does not seem have adverse effects on RNFL thickness or IOP in wet AMD patients. PMID:23638426

Effects of multiple intravitreal anti-VEGF injections on retinal nerve fiber layer and intraocular pressure: a comparative clinical study.

PubMed

Sobacı, Güngör; Güngör, Rıza; Ozge, Gökhan

2013-01-01

To determine the effect of multiple injections of ranibizumab or bevacizumab on retinal nerve fiber layer (RNFL) and intraocular pressure (IOP) in patients with age-related macular degeneration (AMD). This retrospective study includes 35 eyes of 35 patients treated with intravitreal bevacizumab (IVB, 1.25mg/0.05mL) and 30 eyes of 30 patients with intravitreal ranibizumab (IVR, 0.5mg/0.05mL) who had Fast RNFL analysis (Stratus™); IOP measurements were taken 30 minutes and 24 hours after each injection. The mean ages were 68.0±7.5 and 69.1±7.7 years in the IVR and IVB groups, respectively (P=0.55). They underwent (6.3±1.9) and (5.1±1.3) injections (P=0.07) over (13.6±2.1) and (14.05±2.6) months (P=0.45) in the IVR and IVB groups, respectively. Changes in overall and temporal RNFL thickness in IVR-treated eyes (105.3±6.9µm and 74.4±11.2µm) were not different from those in untreated eyes in the IVR group (104.6± 8.4µm and 75.1±12.6µm) (P=0.57 and P=0.41, respectively). Similarly, overall and temporal RNFL thickness in IVB-treated eyes (105.8±8.1µm and 74.5±11.8µm) were not different from those in untreated eyes in the IVB group (104.6±8µm and 74.8±12.9µm) (P=0.42 and P=0.80, respectively). The frequencies of IOP rise (P=0.60) and changes in RNFL thickness from baseline (P=0.16) were comparable between groups. Repeated intravitreal injection of ranibizumab or bevacizumab does not seem have adverse effects on RNFL thickness or IOP in wet AMD patients.

Retinal ganglion cell complex and peripapillary retinal nerve fiber layer thicknesses following carotid endarterectomy.

PubMed

Guclu, Orkut; Guclu, Hande; Huseyin, Serhat; Korkmaz, Selcuk; Yuksel, Volkan; Canbaz, Suat; Pelitli Gurlu, Vuslat

2018-06-23

To examine changes in retinal ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thicknesses by optical coherence tomography (OCT) in contralateral and ipsilatateral eyes of carotid artery stenosis (CAS) patients before and after carotid endarterectomy (CEA). Forty-two consecutive patients diagnosed with CAS (70-99% stenosis rate) who underwent CEA were included in this prospective cross-sectional study. The indication for CEA was based on the Asymptomatic Carotid Atherosclerosis Study. Doppler ultrasonography and computed tomography angiography were performed to calculate CAS. All the subjects underwent an ophthalmological examination, including best corrected visual acuity (BCVA), intraocular pressure (IOP) measurements, biomicroscopy, fundoscopy, and OCT before and after the surgery. The mean preoperative intraocular pressure was 15.2 ± 2.1 mmHg in the ipsilateral eye and 15.8 ± 2.7 in the contralateral eye. The mean postoperative intraocular pressure in the ipsilateral and contralateral eye was 18.6 ± 3.0 and 19.3 ± 3.8, respectively. The intraocular pressure was significantly higher in postoperative eyes (p = 0.0001). There was a statistically significant decrease in peripapillary RNFL thickness in superior quadrants postoperatively in ipsilateral eyes. The retinal GCC layer thickness was not significantly different before and after CEA in ipsilateral and contralateral eyes. Carotid endarterectomy results in thinning of the superior peripapillary RNFL thickness. To the best of our knowledge, this is the first study to examine peripapillary RNFL and GCC thicknesses before and after CEA.

Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure

PubMed Central

Wei, Yantao; Jiang, Hong; Shi, Yingying; Qu, Dongyi; Gregori, Giovanni; Zheng, Fang; Rundek, Tatjana; Wang, Jianhua

2017-01-01

Purpose To characterize age-related alterations in the retinal microcirculation, microvascular network, and microstructure in healthy subjects. Methods Seventy-four healthy subjects aged from 18 to 82 years were recruited and divided into four age groups (G1 with age <35 years, G2 with age 35 ∼ 49 years, G3 with age 50 ∼ 64 years, and G4 with age ≥65 years). Custom ultra-high resolution optical coherence tomography (UHR-OCT) was used to acquire six intraretinal layers of the macula. OCT angiography (OCTA) was used to image the retinal microvascular network. The retinal blood flow velocity (BFV) was measured using a Retinal Function Imager (RFI). Results Compared to G1, G2 had significant thinning of the retinal nerve fiber layer (RNFL) (P < 0.05), while G3 had thinning of the RNFL and ganglion cell and inner plexiform layer (GCIPL) (P < 0.05), in addition to thickening of the outer plexiform layer (OPL) and photoreceptor layer (PR) (P < 0.05). G4 had loss in retinal vessel density, thinning in RNFL and GCIPL, and decrease in venular BFV, in addition to thickening of the OPL and PR (P < 0.05). Age was negatively related to retinal vessel densities, the inner retinal layers, and venular BFV (P < 0.05). By contrast, age was positively related to OPL and PR (P < 0.05). Conclusions During aging, decreases in retinal vessel density, inner retinal layer thickness, and venular BFV were evident and impacted each other as observed by simultaneous changes in multiple retinal components. PMID:28744554

Likelihood ratios for glaucoma diagnosis using spectral-domain optical coherence tomography.

PubMed

Lisboa, Renato; Mansouri, Kaweh; Zangwill, Linda M; Weinreb, Robert N; Medeiros, Felipe A

2013-11-01

To present a methodology for calculating likelihood ratios for glaucoma diagnosis for continuous retinal nerve fiber layer (RNFL) thickness measurements from spectral-domain optical coherence tomography (spectral-domain OCT). Observational cohort study. A total of 262 eyes of 187 patients with glaucoma and 190 eyes of 100 control subjects were included in the study. Subjects were recruited from the Diagnostic Innovations Glaucoma Study. Eyes with preperimetric and perimetric glaucomatous damage were included in the glaucoma group. The control group was composed of healthy eyes with normal visual fields from subjects recruited from the general population. All eyes underwent RNFL imaging with Spectralis spectral-domain OCT. Likelihood ratios for glaucoma diagnosis were estimated for specific global RNFL thickness measurements using a methodology based on estimating the tangents to the receiver operating characteristic (ROC) curve. Likelihood ratios could be determined for continuous values of average RNFL thickness. Average RNFL thickness values lower than 86 μm were associated with positive likelihood ratios (ie, likelihood ratios greater than 1), whereas RNFL thickness values higher than 86 μm were associated with negative likelihood ratios (ie, likelihood ratios smaller than 1). A modified Fagan nomogram was provided to assist calculation of posttest probability of disease from the calculated likelihood ratios and pretest probability of disease. The methodology allowed calculation of likelihood ratios for specific RNFL thickness values. By avoiding arbitrary categorization of test results, it potentially allows for an improved integration of test results into diagnostic clinical decision making. Copyright © 2013. Published by Elsevier Inc.

Optical coherence tomography in papilledema and pseudopapilledema with and without optic nerve head drusen.

PubMed

Bassi, Shikha Talwar; Mohana, Kuppuswamy Parthasarthy

2014-12-01

To compare the spectral domain optical coherence tomography (SD-OCT) findings of the optic disc and the peripapillary retina of patients with a true papilledema and pseudopapilledema with and without optic nerve head drusen (ONHD). Retrospective Case Control Study. Peripapillary retinal nerve fiber layer (PPRNFL) thickness as depicted by SD-OCT of 94 eyes of 66 patients with papilledema (30 eyes), pseudopapiledema (31 eyes), and normal controls (33 eyes) was analyzed. The mean RNFL thickness, total retinal thickness (TRT) at a superior and inferior edge of the disc and the quadrant wise topography of increased RNFL were compared in all three groups. Sensitivity, specificity, and area under the receiver operating characteristic curve (AROC) were calculated for all the parameters. The median RNFL thickness was 185.4 (129.5-349.3 μm), 122.3 (109-156.3 μm) and 91.62 ± 7 μm in papilledema, pseudopapilledema, and controls, respectively. Papilledema group had thicker PPRNFL in all quadrants except temporal quadrant. TRT was thicker in papilledema and pseudopapilledema compared to controls. ONHD could be directly visualized as high reflective clumps in the sub-retinal space or the RNFL in 30 eyes. Increased RNFL thickness in all four quadrants was noted 43.3% in papilledema and 9.7% in pseudopapilledema. Normal RNFL thickness in all four quadrants was noted in 0% in papilledema and 32.3% in pseudopapilledema. Nasal RNFL had the highest AROC (0.792) indicating high diagnostic ability to differentiate papilledema from pseudopapilledema. SD-OCT can be used as a tool to differentiate between papilledema and pseudopapilledema.

Glaucoma diagnostic capacity of optic nerve head haemoglobin measures compared with spectral domain OCT and HRT III confocal tomography.

PubMed

Mendez-Hernandez, Carmen; Rodriguez-Uña, Ignacio; Gonzalez-de-la Rosa, Manuel; Arribas-Pardo, Paula; Garcia-Feijoo, Julian

2016-11-01

The computer program laguna onhe determines optic nerve head haemoglobin (ONH Hb) on retinal photographs based on detecting colour differences. This study compares the diagnostic capacity of Laguna ONhE with that of spectral domain optical coherence tomography (OCT) and confocal tomography (HRT III). In a prospective, observational, cross-sectional study, glaucomatous (n = 66) and healthy (n = 52) eyes were examined by Spectralis OCT, HRT III and Laguna ONhE. The following Laguna ONhE variables were determined: ONH Hb across the vertical disc diameter (8&20 Hb), estimated cup-disc ratio (C/D) and the glaucoma discriminant function (GDF), which combines the slope of Hb amount with the mean in 8&20 Hb. The three diagnostic methods were compared by calculating areas under ROC curves (AUCs). Correlations between variables were assessed through Spearman's rho coefficient. Areas under ROC curves (AUCs) were 0.785 (95% CI: 0.700-0.863) for GDF, 0.807 (95% CI: 0.730-0.883) for OCT retinal nerve fibre layer thickness (OCT-RNFL) and 0.714 (95% CI: 0.618-0.810) and 0.721 (95% CI: 0.628-0.815) for the HRT III variable GPS (glaucoma probability score) and vertical C/D ratio, respectively. Glaucoma discriminant function (GDF) was correlated with OCT-RNFL (0.587, p 0.001; 0.507, p 0.045; and -0.119, p 0.713 for mild, moderate and advanced glaucoma, respectively), mostly so with inferior OCT-RNFL (0.622; p < 0.001). Glaucoma discriminant function (GDF)-HRT III correlations were lower (rim area 0.471, p < 0.0001; rim/disc area 0.426, p < 0.0001; vertical C/D -0.413, p < 0.0001; GPS -0.408, p < 0.0001; rim volume 0.341, p < 0.0001). Similar diagnostic power was observed for Laguna ONhE, Spectralis OCT and HRT III. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Distinguishing ischaemic optic neuropathy from optic neuritis by ganglion cell analysis.

PubMed

Erlich-Malona, Natalie; Mendoza-Santiesteban, Carlos E; Hedges, Thomas R; Patel, Nimesh; Monaco, Caitlin; Cole, Emily

2016-12-01

To determine whether a pattern of altitudinal ganglion cell loss, as detected and measured by optical coherence tomography (OCT), can be used to distinguish non-arteritic ischaemic optic neuropathy (NAION) from optic neuritis (ON) during the acute phase, and whether the rate or severity of ganglion cell loss differs between the two diseases. We performed a retrospective, case-control study of 44 patients (50 eyes) with ON or NAION and 44 age-matched controls. Non-arteritic ischaemic optic neuropathy and ON patients had OCT at presentation and four consecutive follow-up visits. Controls had OCT at one point in time. The ganglion cell complex (GCC) was evaluated in the macula, and the retinal nerve fibre layer (RNFL) was evaluated in the peripapillary region. Ganglion cell complex thickness, RNFL thickness and GCC mean superior and inferior hemispheric difference were compared between NAION and ON patients at each time-point using unpaired t-tests and between disease and control subjects at first measurement using paired t-tests. Mean time from onset of symptoms to initial presentation was 10.7 ± 6.6 days in NAION and 11.7 ± 8.6 days in ON (p = 0.67). There was a significantly greater vertical hemispheric difference in GCC thickness in NAION patients than ON patients at all time-points (5.5-10.7 μm versus 3.1-3.6 μm, p = 0.01-0.049). Mean GCC thickness was significantly decreased at less than 2 weeks after onset in NAION compared to age-matched controls (72.1 μm versus 82.1 μm, p < 0.001), as well as in ON compared to age-matched controls (74.3 μm versus 84.5 μm, p < 0.001). Progression and severity of GCC and RNFL loss did not differ significantly between NAION and ON. A quantitative comparison of mean superior and inferior hemispheric GCC thickness with OCT may be used to distinguish NAION from ON. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Intraobserver reproducibility of retinal nerve fiber layer measurements using scanning laser polarimetry and optical coherence tomography in normal and ocular hypertensive subjects.

PubMed

Lleó-Pérez, A; Ortuño-Soto, A; Rahhal, M S; Martínez-Soriano, F; Sanchis-Gimeno, J A

2004-01-01

To evaluate quantitatively the intraobserver reproducibility of measurements of the retinal nerve fiber layer (RNFL) in healthy subjects and an ocular hypertensive population using two nerve fiber analyzers. Sixty eyes of normal (n=30) and ocular hypertensive subjects (n=30) were consecutively recruited for this study and underwent a complete ophthalmologic examination and achromatic automated perimetry. RNFL were measured using scanning laser polarimeter (GDx-VCC) and optical coherence tomography (OCT Model 3000). Reproducibility of the RNFL measurements obtained with both nerve fiber analyzers were compared using the coefficient of variation. In both groups the authors found fair correlations between the two methods in all ratio and thickness parameters. The mean coefficient of variation for measurement of the variables ranged from 2.24% to 13.12% for GDx-VCC, and from 5.01% to 9.24% for OCT Model 3000. The authors could not detect any significant differences between healthy and ocular hypertensive eyes, although in normal eyes the correlations improved slightly. Nevertheless, the test-retest correlation was slightly better for GDx-VCC than for OCT Model 3000 (5.55% and 7.11%, respectively). Retinal mapping software of both nerve fiber analyzers allows reproducible measurement of RNFL in both healthy subjects and ocular hypertensive eyes, and shows fair correlations and good intraobserver reproducibility. However, in our study, GDx showed a better test-retest correlation.

Glaucoma Progression Detection by Retinal Nerve Fiber Layer Measurement Using Scanning Laser Polarimetry: Event and Trend Analysis

PubMed Central

Moon, Byung Gil; Cho, Jung Woo; Kang, Sung Yong; Yun, Sung-Cheol; Na, Jung Hwa; Lee, Youngrok; Kook, Michael S.

2012-01-01

Purpose To evaluate the use of scanning laser polarimetry (SLP, GDx VCC) to measure the retinal nerve fiber layer (RNFL) thickness in order to evaluate the progression of glaucoma. Methods Test-retest measurement variability was determined in 47 glaucomatous eyes. One eye each from 152 glaucomatous patients with at least 4 years of follow-up was enrolled. Visual field (VF) loss progression was determined by both event analysis (EA, Humphrey guided progression analysis) and trend analysis (TA, linear regression analysis of the visual field index). SLP progression was defined as a reduction of RNFL exceeding the predetermined repeatability coefficient in three consecutive exams, as compared to the baseline measure (EA). The slope of RNFL thickness change over time was determined by linear regression analysis (TA). Results Twenty-two eyes (14.5%) progressed according to the VF EA, 16 (10.5%) by VF TA, 37 (24.3%) by SLP EA and 19 (12.5%) by SLP TA. Agreement between VF and SLP progression was poor in both EA and TA (VF EA vs. SLP EA, k = 0.110; VF TA vs. SLP TA, k = 0.129). The mean (±standard deviation) progression rate of RNFL thickness as measured by SLP TA did not significantly differ between VF EA progressors and non-progressors (-0.224 ± 0.148 µm/yr vs. -0.218 ± 0.151 µm/yr, p = 0.874). SLP TA and EA showed similar levels of sensitivity when VF progression was considered as the reference standard. Conclusions RNFL thickness as measurement by SLP was shown to be capable of detecting glaucoma progression. Both EA and TA of SLP showed poor agreement with VF outcomes in detecting glaucoma progression. PMID:22670073

Glaucoma progression detection by retinal nerve fiber layer measurement using scanning laser polarimetry: event and trend analysis.

PubMed

Moon, Byung Gil; Sung, Kyung Rim; Cho, Jung Woo; Kang, Sung Yong; Yun, Sung-Cheol; Na, Jung Hwa; Lee, Youngrok; Kook, Michael S

2012-06-01

To evaluate the use of scanning laser polarimetry (SLP, GDx VCC) to measure the retinal nerve fiber layer (RNFL) thickness in order to evaluate the progression of glaucoma. Test-retest measurement variability was determined in 47 glaucomatous eyes. One eye each from 152 glaucomatous patients with at least 4 years of follow-up was enrolled. Visual field (VF) loss progression was determined by both event analysis (EA, Humphrey guided progression analysis) and trend analysis (TA, linear regression analysis of the visual field index). SLP progression was defined as a reduction of RNFL exceeding the predetermined repeatability coefficient in three consecutive exams, as compared to the baseline measure (EA). The slope of RNFL thickness change over time was determined by linear regression analysis (TA). Twenty-two eyes (14.5%) progressed according to the VF EA, 16 (10.5%) by VF TA, 37 (24.3%) by SLP EA and 19 (12.5%) by SLP TA. Agreement between VF and SLP progression was poor in both EA and TA (VF EA vs. SLP EA, k = 0.110; VF TA vs. SLP TA, k = 0.129). The mean (±standard deviation) progression rate of RNFL thickness as measured by SLP TA did not significantly differ between VF EA progressors and non-progressors (-0.224 ± 0.148 µm/yr vs. -0.218 ± 0.151 µm/yr, p = 0.874). SLP TA and EA showed similar levels of sensitivity when VF progression was considered as the reference standard. RNFL thickness as measurement by SLP was shown to be capable of detecting glaucoma progression. Both EA and TA of SLP showed poor agreement with VF outcomes in detecting glaucoma progression.

Comprehensive Three-Dimensional Analysis of the Neuroretinal Rim in Glaucoma Using High-Density Spectral-Domain Optical Coherence Tomography Volume Scans

PubMed Central

Tsikata, Edem; Lee, Ramon; Shieh, Eric; Simavli, Huseyin; Que, Christian J.; Guo, Rong; Khoueir, Ziad; de Boer, Johannes; Chen, Teresa C.

2016-01-01

Purpose To describe spectral-domain optical coherence tomography (OCT) methods for quantifying neuroretinal rim tissue in glaucoma and to compare these methods to the traditional retinal nerve fiber layer thickness diagnostic parameter. Methods Neuroretinal rim parameters derived from three-dimensional (3D) volume scans were compared with the two-dimensional (2D) Spectralis retinal nerve fiber layer (RNFL) thickness scans for diagnostic capability. This study analyzed one eye per patient of 104 glaucoma patients and 58 healthy subjects. The shortest distances between the cup surface and the OCT-based disc margin were automatically calculated to determine the thickness and area of the minimum distance band (MDB) neuroretinal rim parameter. Traditional 150-μm reference surface–based rim parameters (volume, area, and thickness) were also calculated. The diagnostic capabilities of these five parameters were compared with RNFL thickness using the area under the receiver operating characteristic (AUROC) curves. Results The MDB thickness had significantly higher diagnostic capability than the RNFL thickness in the nasal (0.913 vs. 0.818, P = 0.004) and temporal (0.922 vs. 0.858, P = 0.026) quadrants and the inferonasal (0.950 vs. 0.897, P = 0.011) and superonasal (0.933 vs. 0.868, P = 0.012) sectors. The MDB area and the three neuroretinal rim parameters based on the 150-μm reference surface had diagnostic capabilities similar to RNFL thickness. Conclusions The 3D MDB thickness had a high diagnostic capability for glaucoma and may be of significant clinical utility. It had higher diagnostic capability than the RNFL thickness in the nasal and temporal quadrants and the inferonasal and superonasal sectors. PMID:27768203

A Diagnostic Calculator for Detecting Glaucoma on the Basis of Retinal Nerve Fiber Layer, Optic Disc, and Retinal Ganglion Cell Analysis by Optical Coherence Tomography.

PubMed

Larrosa, José Manuel; Moreno-Montañés, Javier; Martinez-de-la-Casa, José María; Polo, Vicente; Velázquez-Villoria, Álvaro; Berrozpe, Clara; García-Granero, Marta

2015-10-01

The purpose of this study was to develop and validate a multivariate predictive model to detect glaucoma by using a combination of retinal nerve fiber layer (RNFL), retinal ganglion cell-inner plexiform (GCIPL), and optic disc parameters measured using spectral-domain optical coherence tomography (OCT). Five hundred eyes from 500 participants and 187 eyes of another 187 participants were included in the study and validation groups, respectively. Patients with glaucoma were classified in five groups based on visual field damage. Sensitivity and specificity of all glaucoma OCT parameters were analyzed. Receiver operating characteristic curves (ROC) and areas under the ROC (AUC) were compared. Three predictive multivariate models (quantitative, qualitative, and combined) that used a combination of the best OCT parameters were constructed. A diagnostic calculator was created using the combined multivariate model. The best AUC parameters were: inferior RNFL, average RNFL, vertical cup/disc ratio, minimal GCIPL, and inferior-temporal GCIPL. Comparisons among the parameters did not show that the GCIPL parameters were better than those of the RNFL in early and advanced glaucoma. The highest AUC was in the combined predictive model (0.937; 95% confidence interval, 0.911-0.957) and was significantly (P = 0.0001) higher than the other isolated parameters considered in early and advanced glaucoma. The validation group displayed similar results to those of the study group. Best GCIPL, RNFL, and optic disc parameters showed a similar ability to detect glaucoma. The combined predictive formula improved the glaucoma detection compared to the best isolated parameters evaluated. The diagnostic calculator obtained good classification from participants in both the study and validation groups.

Confocal Adaptive Optics Imaging of Peripapillary Nerve Fiber Bundles: Implications for Glaucomatous Damage Seen on Circumpapillary OCT Scans.

PubMed

Hood, Donald C; Chen, Monica F; Lee, Dongwon; Epstein, Benjamin; Alhadeff, Paula; Rosen, Richard B; Ritch, Robert; Dubra, Alfredo; Chui, Toco Y P

2015-04-01

To improve our understanding of glaucomatous damage as seen on circumpapillary disc scans obtained with frequency-domain optical coherence tomography (fdOCT), fdOCT scans were compared to images of the peripapillary retinal nerve fiber (RNF) bundles obtained with an adaptive optics-scanning light ophthalmoscope (AO-SLO). The AO-SLO images and fdOCT scans were obtained on 6 eyes of 6 patients with deep arcuate defects (5 points ≤-15 db) on 10-2 visual fields. The AO-SLO images were montaged and aligned with the fdOCT images to compare the RNF bundles seen with AO-SLO to the RNF layer thickness measured with fdOCT. All 6 eyes had an abnormally thin (1% confidence limit) RNF layer (RNFL) on fdOCT and abnormal (hyporeflective) regions of RNF bundles on AO-SLO in corresponding regions. However, regions of abnormal, but equal, RNFL thickness on fdOCT scans varied in appearance on AO-SLO images. These regions could be largely devoid of RNF bundles (5 eyes), have abnormal-appearing bundles of lower contrast (6 eyes), or have isolated areas with a few relatively normal-appearing bundles (2 eyes). There also were local variations in reflectivity of the fdOCT RNFL that corresponded to the variations in AO-SLO RNF bundle appearance. Relatively similar 10-2 defects with similar fdOCT RNFL thickness profiles can have very different degrees of RNF bundle damage as seen on fdOCT and AO-SLO. While the results point to limitations of fdOCT RNFL thickness as typically analyzed, they also illustrate the potential for improving fdOCT by attending to variations in local intensity.

Retinal Nerve Fiber Layer Thickness Changes in the Pseudoexfoliation Syndrome: A Meta-Analysis of Case-Control Studies.

PubMed

Yu, Ji-Guo; Huang, Qing; Zhou, Xiao-Fang; Ding, Yi; Li, Jing; Xiang, Yi

2018-01-01

To evaluate and compare changes in retinal nerve fiber layer (RNFL) thickness in patients with the pseudoexfoliation syndrome (PXS) and healthy controls. Case-control studies were selected through an electronic search of the Cochrane Controlled Trials Register, PubMed, and Embase. Results were reviewed to ensure that the included studies met prespecified inclusion/exclusion criteria, and the quality of each study was assessed using the Newcastle-Ottawa Scale. All included studies measured average and 4-quadrant (temporal, superior, nasal, and inferior) RNFL thickness using optical coherence tomography (OCT). For the continuous outcomes, we calculated the weighted mean difference (WMD) and 95% confidence intervals (CIs). Eight case-control studies were included in this meta-analysis involving 225 eyes of PXS patients and 208 eyes of healthy controls in total. Statistical analysis revealed that the average RNFL thickness in PXS patients was significantly reduced compared to healthy controls (WMD = -6.91, 95% CI: -9.99 to -3.82, p < 0.0001). Additionally, differences in RNFL thickness in the superior quadrant (WMD = -10.68, 95% CI: -16.40 to -4.95, p = 0.0003), inferior quadrant (WMD = -8.20, 95% CI: -10.85 to -5.55, p < 0.00001), nasal quadrant (WMD = -3.05, 95% CI: -5.21 to -0.90, p = 0.005), and temporal quadrant (WMD = -6.39, 95% CI: -9.98 to -2.80, p = 0.0005) were all significant between the two groups. These results suggest that it is important to evaluate RNFL thickness and the optic nerve head through OCT in patients with PXS in order to determine early glaucomatous damage and start timely intervention prior to visual field loss. © 2017 S. Karger AG, Basel.

The influence of corneal astigmatism on retinal nerve fiber layer thickness and optic nerve head parameter measurements by spectral-domain optical coherence tomography.

PubMed

Liu, Lin; Zou, Jun; Huang, Hui; Yang, Jian-guo; Chen, Shao-rong

2012-05-23

To evaluate the influence of corneal astigmatism (CA) on retinal nerve fiber layer (RNFL) thickness and optic nerve head(ONH) parameters measured with spectral-domain optical coherence tomography (OCT) in high myopes patients before refractive surgery. Seventy eyes of 35 consecutive refractive surgery candidates were included in this study. The mean age of the subjects was 26.42 ± 6.95 years, the average CA was -1.17 diopters (D; SD 0.64; range -0.2 to-3.3D), All subjects in this study were WTR CA. 34 eyes were in the normal CA group with a mean CA was -0.67 ± 0.28D, 36 eyes were in the high CA group with an average CA of -1.65 ± 0.49D. All subjects underwent ophthalmic examination and imaging with the Cirrus HD OCT. No significant difference was noted in the average cup-to-disk ratio, vertical cup-to-disk ratio and cup volume (all P values > 0.05). Compared with the normal CA group, the high CA group had a larger disc area and rim area, thinner RNFL thickness in the temporal quadrant, and the superotemporal and inferotemporal peaks were farther to the temporal horizon (All P values < 0.05). There were no significant differences between the two groups in global average RNFL thickness, as well as superior, nasal and inferior quadrant RNFL thickness (all P values > 0.05). The degree of with-the-rule CA should be considered when interpreting ONH parameters and peripapillary RNFL thickness measured by the Cirrus HD OCT. The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1148475676881895.

Are All Retinal Nerve Fiber Layer Defects on Optic Coherence Tomography Glaucomatous?

PubMed Central

Gür Güngör, Sirel; Ahmet, Akman

2017-01-01

Objectives: In this study, we investigated the patients who were referred to our clinic with a prediagnosis of glaucoma based on retinal nerve fiber layer (RNFL) defects on optic coherence tomography (OCT) but were determined to have nonglaucomatous RNLF defects upon detailed examination. Materials and Methods: The ophthalmic examination notes, OCT images, Heidelberg retinal tomography (HRT) II and fundus photographs of 357 patients were retrospectively evaluated. Final diagnoses of these patients were investigated. Results: Of the 357 patients, 216 (60.5%) were diagnosed as open angle glaucoma, 33 (9.2%) as low-tension glaucoma, 39 (10.9%) as pre-perimetric glaucoma. The ophthalmic examinations of 14 patients (3.9%) were normal and there were no RNFL defects in OCT examinations after dilatation. In 39 patients (10.9%), the ophthalmic and optic disc examinations were completely normal and no etiologic factor explaining RNFL defects was found. Twenty-two eyes of 16 patients (4.5%) were included in this study (the mean age was 53.8±11.5 years; 9 men and 7 women). After detailed questioning of the medical history and systemic and neurologic examinations, a diagnosis of ischemic optic neuropathy was made in 11 eyes (10 patients) (2.8%), optic neuritis in 3 eyes (2 patients) (0.6%), optic disc drusen in 4 eyes (2 patients) (0.6%), pseudotumor cerebri in 2 eyes (1 patient) (0.3%), and cerebral palsy in 2 eyes (1 patient) (0.3%). Conclusion: Decrease in RNFL thickness on OCT images alone may be misleading in glaucoma examination. In cases where optic disc cupping is not evident, diagnosis should not be based on OCT RNFL examinations alone, and the patient’s medical history, detailed ophthalmic examination, OCT optic disc parameters, HRT, and visual field tests should all be carefully evaluated together. PMID:29109895

Comparison of localized retinal nerve fiber layer defects between a low-teen intraocular pressure group and a high-teen intraocular pressure group in normal-tension glaucoma patients.

PubMed

Kim, Dong Myung; Seo, Je Hyun; Kim, Seok Hwan; Hwang, Seung-Sik

2007-05-01

To compare the features of localized retinal nerve fiber layer (RNFL) defects between a low-teen intraocular pressure (IOP) group and a high-teen IOP group in normal-tension glaucoma (NTG) patients. Seventy-seven eyes of 77 NTG patients showing localized RNFL defects on RNFL photographs and corresponding visual filed defects at the initial visit to a glaucoma specialist were selected for this study. Patients with range of diurnal IOP within low-teen or high-teen in both eyes were included. All participants completed refraction, diurnal IOP measurement, central corneal thickness (CCT) measurement, stereoscopic disc photography, RNFL photography, and automated perimetry. On RNFL photograph, approximation of the defect to the macula (angle alpha) and width of the defects (angle beta) were measured to represent RNFL defects. The patients were divided into 2 groups according to the level of IOP. A low-teen group had highest IOP of 15 mm Hg (group B). Age at diagnosis, percentage of male patients, systemic disease, refraction, CCT, highest IOP, angle alpha, angle beta, and mean deviation and pattern standard deviation of visual field were compared between the 2 groups. Age at diagnosis of NTG, age distribution, percentage of male patients, systemic disease, spherical equivalent of refraction, CCT, mean deviation, and pattern standard deviation were not different between the 2 groups. Highest IOP was 13.8+/-1.2 mm Hg in group A and 19.2+/-1.4 mm Hg in group B (P<0.001). Angle alpha was significantly smaller in group A than in group B (37.0+/-14.0 vs. 56.5+/-21.2 degrees, P<0.001), whereas angle beta was not different between the 2 groups (39.9+/-17.9 vs. 37.5+/-15.9 degrees, P=0.54). There were no significant correlations between spherical equivalent and angle alpha (r=-0.03, P=0.82), between spherical equivalent and angle beta (r=-0.04, P=0.74), and between angle alpha and angle beta (r=-0.21, P=0.07). Localized RNFL defect was closer to the center of the macula in group A than in group B, whereas width of defects was not different between the 2 groups. These findings provide indirect evidence to suggest that more than one pathogenic mechanism may exist in the development of RNFL defects in NTG.

Phenytoin for neuroprotection in patients with acute optic neuritis: a randomised, placebo-controlled, phase 2 trial.

PubMed

Raftopoulos, Rhian; Hickman, Simon J; Toosy, Ahmed; Sharrack, Basil; Mallik, Shahrukh; Paling, David; Altmann, Daniel R; Yiannakas, Marios C; Malladi, Prasad; Sheridan, Rose; Sarrigiannis, Ptolemaios G; Hoggard, Nigel; Koltzenburg, Martin; Gandini Wheeler-Kingshott, Claudia A M; Schmierer, Klaus; Giovannoni, Gavin; Miller, David H; Kapoor, Raju

2016-03-01

Acute demyelinating optic neuritis, a common feature of multiple sclerosis, can damage vision through neurodegeneration in the optic nerve and in its fibres in the retina. Inhibition of voltage-gated sodium channels is neuroprotective in preclinical models. In this study we aimed to establish whether sodium-channel inhibition with phenytoin is neuroprotective in patient with acute optic neuritis. We did a randomised, placebo-controlled, double-blind phase 2 trial at two UK academic hospitals in London and Sheffield. Patients with acute optic neuritis aged 18-60 years, presenting within 2 weeks of onset, with visual acuity of 6/9 or worse, were randomly assigned (1:1) by minimisation via a web-based service to oral phenytoin (maintenance dose 4 mg/kg per day if randomised before or on July 16, 2013, and 6 mg/kg per day if randomised on or after July 17, 2013) or placebo for 3 months, stratified by time from onset, centre, previous multiple sclerosis diagnosis, use of disease-modifying treatment, and use of corticosteroids for acute optic neuritis. Participants and treating and assessing physicians were masked to group assignment. The primary outcome was retinal nerve fibre layer (RNFL) thickness in the affected eye at 6 months, adjusted for fellow-eye RNFL thickness at baseline, analysed in a modified intention-to-treat population of all randomised participants who were followed up at 6 months. Safety was analysed in the entire population, including those who were lost to follow-up. The trial is registered with ClinicalTrials.gov, number NCT 01451593. We recruited 86 participants between Feb 3, 2012, and May 22, 2014 (42 assigned to phenytoin and 44 to placebo). 29 were assigned to phenytoin 4 mg/kg and 13 to phenytoin 6 mg/kg. Five participants were lost to follow-up, so the primary analysis included 81 participants (39 assigned to phenytoin and 42 to placebo). Mean 6-month RNFL thickness in the affected eye at 6 months was 81.46 μm (SD 16.27) in the phenytoin group (a mean decrease of 16.69 μm [SD 13.73] from baseline) versus 74.29 μm (15.14) in the placebo group (a mean decrease of 23.79 μm [13.97] since baseline; adjusted 6-month difference of 7.15 μm [95% CI 1.08-13.22]; p=0.021), corresponding to a 30% reduction in the extent of RNFL loss with phenytoin compared with placebo. Treatment was well tolerated, with five (12%) of 42 patients having a serious adverse event in the phenytoin group (only one, severe rash, was attributable to phenytoin) compared with two (5%) of 44 in the placebo group. These findings support the concept of neuroprotection with phenytoin in patients with acute optic neuritis at concentrations at which it blocks voltage-gated sodium channels selectively. Further investigation in larger clinical trials in optic neuritis and in relapsing multiple sclerosis is warranted. US National Multiple Sclerosis Society, Multiple Sclerosis Society of Great Britain and Northern Ireland, Novartis, UK National Institute for Health Research (NIHR), and NIHR UCLH/UCL Biomedical Research Centre. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of peripapillary retinal nerve fiber layer loss and visual outcome in fellow eyes following sequential bilateral non-arteritic anterior ischemic optic neuropathy.

PubMed

Dotan, Gad; Kesler, Anat; Naftaliev, Elvira; Skarf, Barry

2015-05-01

To report on the correlation of structural damage to the axons of the optic nerve and visual outcome following bilateral non-arteritic anterior ischemic optic neuropathy. A retrospective review of the medical records of 25 patients with bilateral sequential non-arteritic anterior ischemic optic neuropathy was performed. Outcome measures were peripapillary retinal nerve fiber layer thickness measured with the Stratus optical coherence tomography scanner, visual acuity and visual field loss. Median peripapillary retinal nerve fiber layer (RNFL) thickness, mean deviation (MD) of visual field, and visual acuity of initially involved NAION eyes (54.00 µm, -17.77 decibels (dB), 0.4, respectively) were comparable to the same parameters measured following development of second NAION event in the other eye (53.70 µm, p = 0.740; -16.83 dB, p = 0.692; 0.4, p = 0.942, respectively). In patients with bilateral NAION, there was a significant correlation of peripapillary RNFL thickness (r = 0.583, p = 0.002) and MD of the visual field (r = 0.457, p = 0.042) for the pairs of affected eyes, whereas a poor correlation was found in visual acuity of these eyes (r = 0.279, p = 0.176). Peripapillary RNFL thickness following NAION was positively correlated with MD of visual field (r = 0.312, p = 0.043) and negatively correlated with logMAR visual acuity (r = -0.365, p = 0.009). In patients who experience bilateral NAION, the magnitude of RNFL loss is similar in each eye. There is a greater similarity in visual field loss than in visual acuity between the two affected eyes with NAION of the same individual.

Machine learning classifiers for glaucoma diagnosis based on classification of retinal nerve fibre layer thickness parameters measured by Stratus OCT.

PubMed

Bizios, Dimitrios; Heijl, Anders; Hougaard, Jesper Leth; Bengtsson, Boel

2010-02-01

To compare the performance of two machine learning classifiers (MLCs), artificial neural networks (ANNs) and support vector machines (SVMs), with input based on retinal nerve fibre layer thickness (RNFLT) measurements by optical coherence tomography (OCT), on the diagnosis of glaucoma, and to assess the effects of different input parameters. We analysed Stratus OCT data from 90 healthy persons and 62 glaucoma patients. Performance of MLCs was compared using conventional OCT RNFLT parameters plus novel parameters such as minimum RNFLT values, 10th and 90th percentiles of measured RNFLT, and transformations of A-scan measurements. For each input parameter and MLC, the area under the receiver operating characteristic curve (AROC) was calculated. There were no statistically significant differences between ANNs and SVMs. The best AROCs for both ANN (0.982, 95%CI: 0.966-0.999) and SVM (0.989, 95% CI: 0.979-1.0) were based on input of transformed A-scan measurements. Our SVM trained on this input performed better than ANNs or SVMs trained on any of the single RNFLT parameters (p < or = 0.038). The performance of ANNs and SVMs trained on minimum thickness values and the 10th and 90th percentiles were at least as good as ANNs and SVMs with input based on the conventional RNFLT parameters. No differences between ANN and SVM were observed in this study. Both MLCs performed very well, with similar diagnostic performance. Input parameters have a larger impact on diagnostic performance than the type of machine classifier. Our results suggest that parameters based on transformed A-scan thickness measurements of the RNFL processed by machine classifiers can improve OCT-based glaucoma diagnosis.

Retinal nerve fiber layer in primary open-angle glaucoma with high myopia determined by optical coherence tomography and scanning laser polarimetry.

PubMed

Wang, Xiao-en; Wang, Xiao-yu; Gu, Yang-shun; Huang, Zhu

2013-01-01

Fundus changes associated with high myopia (HM) may mask those associated with primary open-angle glaucoma (POAG). This study aim to determine the characteristics of RNFL thickness changes in patients with both POAG and HM and compare these to changes in patients with only HM. The diagnostic capabilities of both OCT and GDxVCC in this subset of patients are also evaluated. Twenty-two eyes with POAG and HM (spherical equivalent (SE) between -6.0 and -12.0 D) were evaluated, and 22 eyes with HM were used for comparison. Characteristic retinal nerve fiber layer (RNFL) thickness profiles in patients with POAG and HM were examined using optical coherence tomography (OCT) and scanning laser polarimetry with variable corneal compensation (GDxVCC), and the diagnostic capabilities of these imaging modalities were compared. RNFL parameters evaluated included superior average (Savg-GDx), inferior average (Iavg-GDx), temporal-superior-nasal- inferior-temporal (TSNIT) average, and nerve fiber indicator (NFI) on GDxVCC and superior average (Savg-OCT), inferior average (Iavg-OCT), nasal average (Navg-OCT), temporal average (Tavg-OCT), and average thickness (AvgThick-OCT) on OCT (fast RNFL scan). Visual field testing was performed and defects were evaluated using mean defect (MD) and pattern standard deviation (PSD). The RNFL parameters (P < 0.05) significantly different between groups included Savg-GDx, Iavg-GDx, TSNIT average, NFI, Savg-OCT, Iavg-OCT, Tavg-OCT, and AvgThick-OCT. Significant correlations existed between TSNIT average and AvgThick-OCT (r = 0.778), TSNIT average and MD (r = 0.749), AvgThick-OCT and MD (r = 0.647), TSNIT average and PSD (r = -0.756), and AvgThick-OCT and PSD (r = -0.784). The area under the receiver operating characteristic curve (AUROC) values of TSNIT average, Savg-GDx, Iavg-GDx, NFI, Savg-OCT, Iavg-OCT, Navg-OCT, Tavg-OCT, and AvgThick-OCT were 0.947, 0.962, 0.973, 0.994, 0.909, 0.917, 0.511, 0.906, and 0.913, respectively. The NFI AUROC was the highest value. RNFL thickness was significantly lower in all but the nasal quadrant in patients with POAG and HM, compared to patients with only HM. Measurements with OCT and GDxVCC were well-correlated, and both modalities detected RNFL thickness changes. However, GDxVCC was better than OCT in detecting POAG in HM patients.

Population-based evaluation of retinal nerve fiber layer, retinal ganglion cell layer, and inner plexiform layer as a diagnostic tool for glaucoma.

PubMed

Springelkamp, Henriët; Lee, Kyungmoo; Wolfs, Roger C W; Buitendijk, Gabriëlle H S; Ramdas, Wishal D; Hofman, Albert; Vingerling, Johannes R; Klaver, Caroline C W; Abràmoff, Michael D; Jansonius, Nomdo M

2014-11-20

We determined the glaucoma screening performance of regional optical coherence tomography (OCT) layer thickness measurements in the peripapillary and macular region, in a population-based setting. Subjects (n = 1224) in the Rotterdam Study underwent visual field testing (Humphrey Field Analyzer) and OCT of the macula and optic nerve head (Topcon 3-D OCT-1000). We determined the mean thicknesses of the retinal nerve fiber layer (RNFL), retinal ganglion cell layer (RGCL), and inner plexiform layer for regions-of-interest; thus, defining a series of OCT parameters, using the Iowa Reference Algorithms. Reference standard was the presence of glaucomatous visual field loss (GVFL); controls were subjects without GVFL, an intraocular pressure (IOP) of 21 mm Hg or less, and no positive family history for glaucoma. We calculated the area under the receiver operating characteristics curve (AUCs) and the sensitivity at 97.5% specificity for each parameter. After excluding 23 subjects with an IOP > 21 mm Hg and 73 subjects with a positive family history for glaucoma, there were 1087 controls and 41 glaucoma cases. Mean RGCL thickness in the inferior half of the macular region showed the highest AUC (0.85; 95% confidence interval [CI] 0.77-0.92) and sensitivity (53.7%; 95% CI, 38.7-68.0%). The mean thickness of the peripapillary RNFL had an AUC of 0.77 (95% CI, 0.69-0.85) and a sensitivity of 24.4% (95% CI, 13.7-39.5%). Macular RGCL loss is at least as common as peripapillary RNFL abnormalities in population-based glaucoma cases. Screening for glaucoma using OCT-derived regional thickness identifies approximately half of those cases of glaucoma as diagnosed by perimetry. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Optical coherence tomography, scanning laser polarimetry and confocal scanning laser ophthalmoscopy in retinal nerve fiber layer measurements of glaucoma patients.

PubMed

Fanihagh, Farsad; Kremmer, Stephan; Anastassiou, Gerasimos; Schallenberg, Maurice

2015-01-01

To determine the correlations and strength of association between different imaging systems in analyzing the retinal nerve fiber layer (RNFL) of glaucoma patients: optical coherence tomography (OCT), scanning laser polarimetry (SLP) and confocal scanning laser ophthalmoscopy (CSLO). 114 eyes of patients with moderate open angle glaucoma underwent spectral domain OCT (Topcon SD-OCT 2000 and Zeiss Cirrus HD-OCT), SLP (GDx VCC and GDx Pro) and CSLO (Heidelberg Retina Tomograph, HRT 3). Correlation coefficients were calculated between the structural parameters yielded by these examinations. The quantitative relationship between the measured RNFL thickness globally and for the four regions (superior, inferior, nasal, temporal) were evaluated with different regression models for all used imaging systems. The strongest correlation of RNFL measurements was found between devices using the same technology like GDx VCC and GDx Pro as well as Topcon OCT and Cirrus OCT. In glaucoma patients, the strongest associations (R²) were found between RNFL measurements of the two optical coherence tomography devices Topcon OCT and Cirrus OCT (R² = 0.513) and between GDx VCC and GDx Pro (R² = 0.451). The results of the OCTs and GDX Pro also had a strong quantitative relationship (Topcon OCT R² = 0.339 and Cirrus OCT R² = 0.347). GDx VCC and the OCTs showed a mild to moderate association (Topcon OCT R² = 0.207 and Cirrus OCT R² = 0.258). The confocal scanning laser ophthalmoscopy (HRT 3) had the lowest association to all other devices (Topcon OCT R² = 0.254, Cirrus OCT R² = 0.158, GDx Pro R² = 0.086 and GDx VCC R² = 0.1). The measurements of the RNFL in glaucoma patients reveal a high correlation of OCT and GDx devices because OCTs can measure all major retinal layers and SLP can detect nerve fibers allowing a comparison between the results of this devices. However, CSLO by means of HRT topography can only measure height values of the retinal surface but it cannot distinguish between different retinal layers. This may explain the rather poor correlations and associations between CSLO measurements and those of all other imaging devices which makes it difficult to compare HRT 3 nerve fiber data. These correlations are important in clinical routine especially when different techniques are used in the follow-up of glaucoma patients.

Evaluation of retinal nerve fiber layer, ganglion cell layer and macular changes in patients with migraine.

PubMed

Tunç, Abdulkadir; Güngen, Belma Doğan; Evliyaoğlu, Ferhat; Aras, Yeşim Güzey; Tekeşin, Aysel Kaya

2017-03-01

The aim of this study was to investigate retinal nerve fiber layer (RNFL), ganglion cell layer (GCL) thickness, macular changes (central subfield thickness (CST), cube average thickness (CAT), cube volume (CV) in patients with migraine using spectral-domain optical coherence tomography (OCT) and to assess if there was any correlation with white matter lesions (WML). In this prospective case-control study, RNFL, GCL thickness and macular changes of 19 migraine patients with aura (MA), 41 migraine without aura (MO) and 60 age- and gender-matched healthy subjects were measured using OCT device. OCT measurements were taken at the same time of the day to minimize the effects of diurnal variation. The average, inferior and superior quadrant RNFL thickness were significantly thinner in patients with migraine (p = 0.017, p = 0.010, p = 0.048). There was also a significant difference between patients with and without aura in the mean and superior quadrant RNFL thickness (p = 0.02, p = 0.043).While there was a significant thinning in CST and CAT in patients with migraine (p = 0.020), there were no significant difference in GCL measurements (p = 0.184). When the groups were compared to the control group, there were significant differences between MA and the control group regarding average, superior and inferior quadrant RNLF thickness (p < 0.001, p = 0.025, p < 0.001). On the other hand, there were significant differences between MO and the control group regarding average and inferior faces (p = 0.037, p = 0.04). When OCT measurements were evaluated according to the frequency of attacks, CST and GCL thickness were significantly thinner in patients who had more than four attacks a month (p = 0.024, p = 0.014). In patients with WML, only CV measurements were significantly thinner than migraine patients without WML (p = 0.014). The decreased RNFL, CST, CAT and CV of the migraine patients might be related to the vascular pathology of the disease. Because WML was not correlated with the same measurements except CV, we think that further studies are needed to evaluate the etiopathologic relationship between OCT measurements and WML in migraine patients.

Optical coherence tomography in papilledema and pseudopapilledema with and without optic nerve head drusen

PubMed Central

Bassi, Shikha Talwar; Mohana, Kuppuswamy Parthasarthy

2014-01-01

Aim: To compare the spectral domain optical coherence tomography (SD-OCT) findings of the optic disc and the peripapillary retina of patients with a true papilledema and pseudopapilledema with and without optic nerve head drusen (ONHD). Study Design: Retrospective Case Control Study. Subjects and Methods: Peripapillary retinal nerve fiber layer (PPRNFL) thickness as depicted by SD-OCT of 94 eyes of 66 patients with papilledema (30 eyes), pseudopapiledema (31 eyes), and normal controls (33 eyes) was analyzed. The mean RNFL thickness, total retinal thickness (TRT) at a superior and inferior edge of the disc and the quadrant wise topography of increased RNFL were compared in all three groups. Sensitivity, specificity, and area under the receiver operating characteristic curve (AROC) were calculated for all the parameters. Results: The median RNFL thickness was 185.4 (129.5–349.3 μm), 122.3 (109–156.3 μm) and 91.62 ± 7 μm in papilledema, pseudopapilledema, and controls, respectively. Papilledema group had thicker PPRNFL in all quadrants except temporal quadrant. TRT was thicker in papilledema and pseudopapilledema compared to controls. ONHD could be directly visualized as high reflective clumps in the sub-retinal space or the RNFL in 30 eyes. Increased RNFL thickness in all four quadrants was noted 43.3% in papilledema and 9.7% in pseudopapilledema. Normal RNFL thickness in all four quadrants was noted in 0% in papilledema and 32.3% in pseudopapilledema. Nasal RNFL had the highest AROC (0.792) indicating high diagnostic ability to differentiate papilledema from pseudopapilledema. Conclusion: SD-OCT can be used as a tool to differentiate between papilledema and pseudopapilledema. PMID:25579359

Diagnostic ability of macular ganglion cell inner plexiform layer measurements in glaucoma using swept source and spectral domain optical coherence tomography.

PubMed

Yang, Zhiyong; Tatham, Andrew J; Weinreb, Robert N; Medeiros, Felipe A; Liu, Ting; Zangwill, Linda M

2015-01-01

To evaluate the diagnostic ability of macular ganglion cell and inner plexiform layer measurements in glaucoma, obtained using swept source (SS) and spectral domain (SD) optical coherence tomography (OCT) and to compare to circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements. The study included 106 glaucomatous eyes of 80 subjects and 41 eyes of 22 healthy subjects from the Diagnostic Innovations in Glaucoma Study. Macular ganglion cell and inner plexiform layer (mGCIPL), macular ganglion cell complex (mGCC) and cpRNFL thickness were assessed using SS-OCT and SD-OCT, and area under the receiver operating characteristic curves (AUCs) were calculated to determine ability to differentiate glaucomatous and healthy eyes and between early glaucomatous and healthy eyes. Mean (± standard deviation) mGCIPL and mGCC thickness were thinner in both healthy and glaucomatous eyes using SS-OCT compared to using SD-OCT. Fixed and proportional biases were detected between SS-OCT and SD-OCT measures. Diagnostic accuracy (AUCs) for differentiating between healthy and glaucomatous eyes for average and sectoral mGCIPL was similar in SS-OCT (0.65 to 0.81) and SD-OCT (0.63 to 0.83). AUCs for average cpRNFL acquired using SS-OCT and SD-OCT tended to be higher (0.83 and 0.85, respectively) than for average mGCC (0.82 and 0.78, respectively), and mGCIPL (0.73 and 0.75, respectively) but these differences did not consistently reach statistical significance. Minimum SD-OCT mGCIPL and mGCC thickness (unavailable in SS-OCT) had the highest AUC (0.86) among macular measurements. Assessment of mGCIPL thickness using SS-OCT or SD-OCT is useful for detecting glaucomatous damage, but measurements are not interchangeable for patient management decisions. Diagnostic accuracies of mGCIPL and mGCC from both SS-OCT and SD-OCT were similar to that of cpRNFL for glaucoma detection.

Diagnostic Ability of Macular Ganglion Cell Inner Plexiform Layer Measurements in Glaucoma Using Swept Source and Spectral Domain Optical Coherence Tomography

PubMed Central

Yang, Zhiyong; Tatham, Andrew J.; Weinreb, Robert N.; Medeiros, Felipe A.; Liu, Ting; Zangwill, Linda M.

2015-01-01

Purpose To evaluate the diagnostic ability of macular ganglion cell and inner plexiform layer measurements in glaucoma, obtained using swept source (SS) and spectral domain (SD) optical coherence tomography (OCT) and to compare to circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements. Methods The study included 106 glaucomatous eyes of 80 subjects and 41 eyes of 22 healthy subjects from the Diagnostic Innovations in Glaucoma Study. Macular ganglion cell and inner plexiform layer (mGCIPL), macular ganglion cell complex (mGCC) and cpRNFL thickness were assessed using SS-OCT and SD-OCT, and area under the receiver operating characteristic curves (AUCs) were calculated to determine ability to differentiate glaucomatous and healthy eyes and between early glaucomatous and healthy eyes. Results Mean (± standard deviation) mGCIPL and mGCC thickness were thinner in both healthy and glaucomatous eyes using SS-OCT compared to using SD-OCT. Fixed and proportional biases were detected between SS-OCT and SD-OCT measures. Diagnostic accuracy (AUCs) for differentiating between healthy and glaucomatous eyes for average and sectoral mGCIPL was similar in SS-OCT (0.65 to 0.81) and SD-OCT (0.63 to 0.83). AUCs for average cpRNFL acquired using SS-OCT and SD-OCT tended to be higher (0.83 and 0.85, respectively) than for average mGCC (0.82 and 0.78, respectively), and mGCIPL (0.73 and 0.75, respectively) but these differences did not consistently reach statistical significance. Minimum SD-OCT mGCIPL and mGCC thickness (unavailable in SS-OCT) had the highest AUC (0.86) among macular measurements. Conclusion Assessment of mGCIPL thickness using SS-OCT or SD-OCT is useful for detecting glaucomatous damage, but measurements are not interchangeable for patient management decisions. Diagnostic accuracies of mGCIPL and mGCC from both SS-OCT and SD-OCT were similar to that of cpRNFL for glaucoma detection. PMID:25978420

Comparison of Optical Coherence Tomography and Scanning Laser Polarimetry Measurements in Patients with Multiple Sclerosis

PubMed Central

Quelly, Amanda; Cheng, Han; Laron, Michal; Schiffman, Jade S.; Tang, Rosa A.

2010-01-01

Purpose To compare optical coherence tomography (OCT) and scanning laser polarimetry (GDx) measurements of the retinal nerve fiber layer (RNFL) in multiple sclerosis (MS) patients with and without optic neuritis (ON). Methods OCT and GDx were performed on 68 MS patients. Qualifying eyes were divided into two groups: 51 eyes with an ON history ≥ 6 months prior (ON eyes), and 65 eyes with no history of ON (non-ON eyes). Several GDx and OCT parameters and criteria were used to define an eye as abnormal, for example, GDx nerve fiber indicator (NFI) above 20 or 30, OCT average RNFL thickness and GDx temporal-superior-nasal-inferior-temporal average (TSNIT) below 5% or 1% of the instruments’ normative database. Agreement between OCT and GDx parameters was reported as percent of observed agreement, along with the AC1 statistic. Linear regression analyses were used to examine the relationship between OCT average RNFL thickness and GDx NFI and TSNIT. Results All OCT and GDx measurements showed significantly more RNFL damage in ON than in non-ON eyes. Agreement between OCT and GDx parameters ranged from 69–90% (AC1 0.37–0.81) in ON eyes, and 52–91% (AC1 = 0.21–0.90) in non-ON eyes. Best agreement was observed between OCT average RNFL thickness (P < 0.01) and NFI (>30) in ON eyes (90%, AC1 = 0.81), and between OCT average RNFL thickness (P < 0.01) and GDx TSNIT average (P < 0.01) in non-ON eyes (91%, AC1 = 0.90). In ON eyes, the OCT average RNFL thickness showed good linear correlation with NFI (R2 = 0.69, P < 0.0001) and TSNIT (R2 = 0.55, P < 0.0001). Conclusions OCT and GDx show good agreement and can be useful in detecting RNFL loss in MS/ON eyes. PMID:20495500

Structure-function relationships using spectral-domain optical coherence tomography: comparison with scanning laser polarimetry.

PubMed

Aptel, Florent; Sayous, Romain; Fortoul, Vincent; Beccat, Sylvain; Denis, Philippe

2010-12-01

To evaluate and compare the regional relationships between visual field sensitivity and retinal nerve fiber layer (RNFL) thickness as measured by spectral-domain optical coherence tomography (OCT) and scanning laser polarimetry. Prospective cross-sectional study. One hundred and twenty eyes of 120 patients (40 with healthy eyes, 40 with suspected glaucoma, and 40 with glaucoma) were tested on Cirrus-OCT, GDx VCC, and standard automated perimetry. Raw data on RNFL thickness were extracted for 256 peripapillary sectors of 1.40625 degrees each for the OCT measurement ellipse and 64 peripapillary sectors of 5.625 degrees each for the GDx VCC measurement ellipse. Correlations between peripapillary RNFL thickness in 6 sectors and visual field sensitivity in the 6 corresponding areas were evaluated using linear and logarithmic regression analysis. Receiver operating curve areas were calculated for each instrument. With spectral-domain OCT, the correlations (r(2)) between RNFL thickness and visual field sensitivity ranged from 0.082 (nasal RNFL and corresponding visual field area, linear regression) to 0.726 (supratemporal RNFL and corresponding visual field area, logarithmic regression). By comparison, with GDx-VCC, the correlations ranged from 0.062 (temporal RNFL and corresponding visual field area, linear regression) to 0.362 (supratemporal RNFL and corresponding visual field area, logarithmic regression). In pairwise comparisons, these structure-function correlations were generally stronger with spectral-domain OCT than with GDx VCC and with logarithmic regression than with linear regression. The largest areas under the receiver operating curve were seen for OCT superior thickness (0.963 ± 0.022; P < .001) in eyes with glaucoma and for OCT average thickness (0.888 ± 0.072; P < .001) in eyes with suspected glaucoma. The structure-function relationship was significantly stronger with spectral-domain OCT than with scanning laser polarimetry, and was better expressed logarithmically than linearly. Measurements with these 2 instruments should not be considered to be interchangeable. Copyright © 2010 Elsevier Inc. All rights reserved.

Automated Quantification of Volumetric Optic Disc Swelling in Papilledema Using Spectral-Domain Optical Coherence Tomography

PubMed Central

Wang, Jui-Kai; Kardon, Randy H.; Kupersmith, Mark J.; Garvin, Mona K.

2012-01-01

Purpose. To develop an automated method for the quantification of volumetric optic disc swelling in papilledema subjects using spectral-domain optical coherence tomography (SD-OCT) and to determine the extent that such volumetric measurements correlate with Frisén scale grades (from fundus photographs) and two-dimensional (2-D) peripapillary retinal nerve fiber layer (RNFL) and total retinal (TR) thickness measurements from SD-OCT. Methods. A custom image-analysis algorithm was developed to obtain peripapillary circular RNFL thickness, TR thickness, and TR volume measurements from SD-OCT volumes of subjects with papilledema. In addition, peripapillary RNFL thickness measures from the commercially available Zeiss SD-OCT machine were obtained. Expert Frisén scale grades were independently obtained from corresponding fundus photographs. Results. In 71 SD-OCT scans, the mean (± standard deviation) resulting TR volumes for Frisén scale 0 to scale 4 were 11.36 ± 0.56, 12.53 ± 1.21, 14.42 ± 2.11, 17.48 ± 2.63, and 21.81 ± 3.16 mm3, respectively. The Spearman's rank correlation coefficient was 0.737. Using 55 eyes with valid Zeiss RNFL measurements, Pearson's correlation coefficient (r) between the TR volume and the custom algorithm's TR thickness, the custom algorithm's RNFL thickness, and Zeiss' RNFL thickness was 0.980, 0.929, and 0.946, respectively. Between Zeiss' RNFL and the custom algorithm's RNFL, and the study's TR thickness, r was 0.901 and 0.961, respectively. Conclusions. Volumetric measurements of the degree of disc swelling in subjects with papilledema can be obtained from SD-OCT volumes, with the mean volume appearing to be roughly linearly related to the Frisén scale grade. Using such an approach can provide a more continuous, objective, and robust means for assessing the degree of disc swelling compared with presently available approaches. PMID:22599584

Clinical validity of macular ganglion cell complex by spectral domain-optical coherence tomography in advanced glaucoma.

PubMed

Sung, Mi-Sun; Kang, Byung-Wan; Kim, Hwang-Gyun; Heo, Hwan; Park, Sang-Woo

2014-08-01

To evaluate the repeatability and diagnostic power of macular ganglion cell complex (mGCC) thickness and peripapillary retinal nerve fiber layer (pRNFL) thickness using a spectral domain-optical coherence tomography in advanced glaucoma. Forty advanced glaucoma patients were enrolled. Patients were divided into 2 groups of 20 patients each, according to the MD between -20 and -10 dB, and <-20 dB. The thickness of mGCC and pRNFL were measured with spectral domain-optical coherence tomography in both the groups. The repeatability of each parameter was assessed in both the groups, and the diagnostic power of each parameter was compared with the normal controls. Comparison of diagnostic power between the pRNFL and mGCC parameters revealed that the area under the receiver operating characteristic curve was not significantly different in patients with advanced glaucoma. The repeatability of pRNFL parameters was similar, irrespective of the severity of glaucoma. However, the repeatability of mGCC parameters became lower as the severity increased in patients with advanced glaucoma. In advanced glaucoma, the measurement of mGCC thickness has similar diagnostic power as the measurement of pRNFL thickness. However, the measurement of mGCC thickness showed a lower repeatability as MD decreased.

Tomographic Structural Changes of Retinal Layers after Internal Limiting Membrane Peeling for Macular Hole Surgery.

PubMed

Faria, Mun Yueh; Ferreira, Nuno P; Cristóvao, Diana M; Mano, Sofia; Sousa, David Cordeiro; Monteiro-Grillo, Manuel

2018-01-01

To highlight tomographic structural changes of retinal layers after internal limiting membrane (ILM) peeling in macular hole surgery. Nonrandomized prospective, interventional study in 38 eyes (34 patients) subjected to pars plana vitrectomy and ILM peeling for idiopathic macular hole. Retinal layers were assessed in nasal and temporal regions before and 6 months after surgery using spectral domain optical coherence tomography. Total retinal thickness increased in the nasal region and decreased in the temporal region. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) showed thinning on both nasal and temporal sides of the fovea. The thickness of the outer plexiform layer (OPL) increased. The outer nuclear layer (ONL) and outer retinal layers (ORL) increased in thickness after surgery in both nasal and temporal regions. ILM peeling is associated with important alterations in the inner retinal layer architecture, with thinning of the RNFL-GCL-IPL complex and thickening of OPL, ONL, and ORL. These structural alterations can help explain functional outcome and could give indications regarding the extent of ILM peeling, even though peeling seems important for higher rate of hole closure. © 2017 S. Karger AG, Basel.

Reproducibility of retinal nerve fiber layer thickness measures using eye tracking in children with nonglaucomatous optic neuropathy.

PubMed

Rajjoub, Raneem D; Trimboli-Heidler, Carmelina; Packer, Roger J; Avery, Robert A

2015-01-01

To determine the intra- and intervisit reproducibility of circumpapillary retinal nerve fiber layer (RNFL) thickness measures using eye tracking-assisted spectral-domain optical coherence tomography (SD OCT) in children with nonglaucomatous optic neuropathy. Prospective longitudinal study. Circumpapillary RNFL thickness measures were acquired with SD OCT using the eye-tracking feature at 2 separate study visits. Children with normal and abnormal vision (visual acuity ≥ 0.2 logMAR above normal and/or visual field loss) who demonstrated clinical and radiographic stability were enrolled. Intra- and intervisit reproducibility was calculated for the global average and 9 anatomic sectors by calculating the coefficient of variation and intraclass correlation coefficient. Forty-two subjects (median age 8.6 years, range 3.9-18.2 years) met inclusion criteria and contributed 62 study eyes. Both the abnormal and normal vision cohort demonstrated the lowest intravisit coefficient of variation for the global RNFL thickness. Intervisit reproducibility remained good for those with normal and abnormal vision, although small but statistically significant increases in the coefficient of variation were observed for multiple anatomic sectors in both cohorts. The magnitude of visual acuity loss was significantly associated with the global (ß = 0.026, P < .01) and temporal sector coefficient of variation (ß = 0.099, P < .01). SD OCT with eye tracking demonstrates highly reproducible RNFL thickness measures. Subjects with vision loss demonstrate greater intra- and intervisit variability than those with normal vision. Copyright © 2015 Elsevier Inc. All rights reserved.

Retina and Nerve Fiber Layer Thickness in Eyes with Thyroid-Associated Ophthalmopathy.

PubMed

Blum Meirovitch, Sharon; Leibovitch, Igal; Kesler, Anat; Varssano, David; Rosenblatt, Amir; Neudorfer, Meira

2017-05-01

Thyroid-associated ophthalmopathy (TAO) is an inflammatory disease that affects the thyroid gland and the eye orbit. Of patients with TAO, 3%-5% have severe sight-threatening disease due to optic neuropathy Optical coherence tomography (OCT), the non-invasive imaging technology that yields high-resolution cross-sectional images of the retina, provides qualitative and quantitative data on the retina. To apply this technique to quantitatively assess retinal nerve fiber layer (RNFL) and macular ring thicknesses in healthy subjects and in patients with TAO to determine their relationship to the severity of the orbital disease. All patients in the ophthalmology clinic who were diagnosed with TAO and underwent OCT imaging as part of their ocular examination comprised the study group, and healthy patients who volunteered to undergo OCT examination served as controls. Results of the complete ophthalmologic examination and OCT findings were collected from medical files, including the thickness of the RNFL and the macula. The study comprised 21 patients and 41 healthy controls. TAO patients exhibited RNFL thickening and inner macula thinning compared to healthy subjects. Mean RNFL thickness was correlated with the severity of the orbital disease. The OCT findings suggest that the retina is involved in TAO, probably as early as the subclinical stage. This highlights the ability of OCT to identify retinal changes earlier and far more accurately than is detected today, enabling earlier diagnosis and more timely treatment to prevent severe visual sequelae.

Influence of corneal power on circumpapillary retinal nerve fiber layer and optic nerve head measurements by spectral-domain optical coherence tomography.

PubMed

Hirasawa, Kazunori; Shoji, Nobuyuki

2017-01-01

To evaluate the influence of corneal power on circumpapillary retinal nerve fiber layer (cpRNFL) and optic nerve head (ONH) measurements by spectral-domain optical coherence tomography (SD-OCT). Twenty-five eyes of 25 healthy participants (mean age 23.6±3.6y) were imaged by SD-OCT using horizontal raster scans. Disposable soft contact lenses of different powers (from -11 to +5 diopters including 0 diopter) were worn to induce 2-diopter changes in corneal power. Differences in the cpRNFL and ONH measurements per diopter of change in corneal power were analyzed. As corneal power increased by 1 diopter, total and quadrant cpRNFL thicknesses, except for the nasal sector, decreased by --0.19 to -0.32 µm ( P <0.01). Furthermore, the disc, cup, and rim areas decreased by -0.017, -0.007, and -0.015 mm 2 , respectively ( P <0.001); the cup and rim volumes decreased by -0.0013 and -0.006 mm 3 , respectively ( P <0.01); and the vertical and horizontal disc diameters decreased by -0.006 and -0.007 mm, respectively ( P <0.001). For more precise OCT imaging, the ocular magnification should be corrected by considering both the axial length and corneal power. However, the effect of corneal power changes on cpRNFL thickness and ONH topography are small when compare with those of the axial length.

Association between retinal nerve fiber layer thickness and magnetic resonance imaging findings and intelligence in patients with multiple sclerosis.

PubMed

Ashtari, Fereshteh; Emami, Parisa; Akbari, Mojtaba

2015-01-01

Multiple Sclerosis (MS) is a neurological disease in which demyelination and axonal loss leads to progressive disability. Cognition impairment is among the most common complication. Studying axonal loss in the retina is a new marker for MS. The main goal of our study is to search for correlations between magnetic resonance imaging (MRI) findings and the retinal nerve fiber layer (RNFL) thickness at the macula and head of the optic nerve and Wechsler Adult Intelligence Scale-Revised (WAIS-R) Scores that assess multiple domains of intelligence, and to explore the relationship between changes in the RNFL thickness with intellectual and cognitive dysfunction. A prospective cross-sectional study was conducted at the University Hospital of Kashani, Isfahan, Iran, from September to December 2013. All patients were assessed with a full-scale intelligence quotient (IQ) on the WAIS-R. An optical coherence tomography study and brain MRI were performed in the same week for all the patients. Statistical analysis was conducted by using a bivariate correlation, by utilizing SPSS 20.0. A P value ≤ 0.05 was the threshold of statistical significance. Examination of a 100 patients showed a significant correlation between the average RNFL thickness of the macula and the verbal IQ (P value = 0.01) and full IQ (P value = 0.01). There was a significant correlation between brain atrophy and verbal IQ. The RNFL loss was correlated with verbal IQ and full IQ.

Impacts of age and sex on retinal layer thicknesses measured by spectral domain optical coherence tomography with Spectralis.

PubMed

Nieves-Moreno, María; Martínez-de-la-Casa, José M; Morales-Fernández, Laura; Sánchez-Jean, Rubén; Sáenz-Francés, Federico; García-Feijoó, Julián

2018-01-01

To examine differences in individual retinal layer thicknesses measured by spectral domain optical coherence tomography (SD-OCT) (Spectralis®) produced with age and according to sex. Cross-sectional, observational study. The study was conducted in 297 eyes of 297 healthy subjects aged 18 to 87 years. In one randomly selected eye of each participant the volume and mean thicknesses of the different macular layers were measured by SD-OCT using the instrument's macular segmentation software. Volume and mean thickness of macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), retinal pigmentary epithelium (RPE) and photoreceptor layer (PR). Retinal thickness was reduced by 0.24 μm for every one year of age. Age adjusted linear regression analysis revealed mean GCL, IPL, ONL and PR thickness reductions and a mean OPL thickness increase with age. Women had significantly lower mean GCL, IPL, INL, ONL and PR thicknesses and volumes and a significantly greater mRNFL volume than men. The thickness of most retinal layers varies both with age and according to sex. Longitudinal studies are needed to determine the rate of layer thinning produced with age.

Diagnostic Abilities of Variable and Enhanced Corneal Compensation Algorithms of GDx in Different Severities of Glaucoma.

PubMed

Yadav, Ravi K; Begum, Viquar U; Addepalli, Uday K; Senthil, Sirisha; Garudadri, Chandra S; Rao, Harsha L

2016-02-01

To compare the abilities of retinal nerve fiber layer (RNFL) parameters of variable corneal compensation (VCC) and enhanced corneal compensation (ECC) algorithms of scanning laser polarimetry (GDx) in detecting various severities of glaucoma. Two hundred and eighty-five eyes of 194 subjects from the Longitudinal Glaucoma Evaluation Study who underwent GDx VCC and ECC imaging were evaluated. Abilities of RNFL parameters of GDx VCC and ECC to diagnose glaucoma were compared using area under receiver operating characteristic curves (AUC), sensitivities at fixed specificities, and likelihood ratios. After excluding 5 eyes that failed to satisfy manufacturer-recommended quality parameters with ECC and 68 with VCC, 56 eyes of 41 normal subjects and 161 eyes of 121 glaucoma patients [36 eyes with preperimetric glaucoma, 52 eyes with early (MD>-6 dB), 34 with moderate (MD between -6 and -12 dB), and 39 with severe glaucoma (MD<-12 dB)] were included for the analysis. Inferior RNFL, average RNFL, and nerve fiber indicator parameters showed the best AUCs and sensitivities both with GDx VCC and ECC in diagnosing all severities of glaucoma. AUCs and sensitivities of all RNFL parameters were comparable between the VCC and ECC algorithms (P>0.20 for all comparisons). Likelihood ratios associated with the diagnostic categorization of RNFL parameters were comparable between the VCC and ECC algorithms. In scans satisfying the manufacturer-recommended quality parameters, which were significantly greater with ECC than VCC algorithm, diagnostic abilities of GDx ECC and VCC in glaucoma were similar.

Macular Ganglion Cell Imaging Study: Covariate Effects on the Spectral Domain Optical Coherence Tomography for Glaucoma Diagnosis.

PubMed

Jeong, Jae Hoon; Choi, Yun Jeong; Park, Ki Ho; Kim, Dong Myung; Jeoung, Jin Wook

2016-01-01

To evaluate the effect of multiple covariates on the diagnostic performance of the Cirrus high-definition optical coherence tomography (HD-OCT) for glaucoma detection. A prospective case-control study was performed and included 173 recently diagnosed glaucoma patients and 63 unaffected individuals from the Macular Ganglion Cell Imaging Study. Regression analysis of receiver operating characteristic were conducted to evaluate the influence of age, spherical equivalent, axial length, optic disc size, and visual field index on the macular ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (RNFL) measurements. Disease severity, as measured by visual field index, had a significant effect on the diagnostic performance of all Cirrus HD-OCT parameters. Age, axial length and optic disc size were significantly associated with diagnostic accuracy of average peripapillary RNFL thickness, whereas axial length had a significant effect on the diagnostic accuracy of average GCIPL thickness. Diagnostic performance of the Cirrus HD-OCT may be more accurate in the advanced stages of glaucoma than at earlier stages. A smaller optic disc size was significantly associated with improved the diagnostic ability of average RNFL thickness measurements; however, GCIPL thickness may be less affected by age and optic disc size.

Enhanced Diagnostic Capability for Glaucoma of 3-Dimensional versus 2-Dimensional Neuroretinal Rim Parameters Using Spectral Domain Optical Coherence Tomography

PubMed Central

Fan, Kenneth Chen; Tsikata, Edem; Khoueir, Ziad; Simavli, Huseyin; Guo, Rong; DeLuna, Regina; Pandit, Sumir; Que, Christian John; de Boer, Johannes F.; Chen, Teresa C.

2017-01-01

Purpose To compare the diagnostic capability of 3-dimensional (3D) neuroretinal rim parameters with existing 2-dimensional (2D) neuroretinal and retinal nerve fiber layer (RNFL) thickness rim parameters using spectral domain optical coherence tomography (SD-OCT) volume scans Materials and Methods Design Institutional prospective pilot study. Study population 65 subjects (35 open angle glaucoma patients, 30 normal patients). Observation procedures One eye of each subject was included. SD-OCT was used to obtain 2D retinal nerve fiber layer (RNFL) thickness values and five neuroretinal rim parameters [i.e. 3D minimum distance band (MDB) thickness, 3D Bruch’s membrane opening-minimum rim width (BMO-MRW), 3D rim volume, 2D rim area, and 2D rim thickness]. Main outcome measures Area under the receiver operating characteristic (AUROC) curve values, sensitivity, specificity. Results Comparing all 3D with all 2D parameters, 3D rim parameters (MDB, BMO-MRW, rim volume) generally had higher AUROC curve values (range 0.770–0.946) compared to 2D parameters (RNFL thickness, rim area, rim thickness; range 0.678–0.911). For global region analyses, all 3D rim parameters (BMO-MRW, rim volume, MDB) were equal to or better than 2D parameters (RNFL thickness, rim area, rim thickness; p-values from 0.023–1.0). Among the three 3D rim parameters (MDB, BMO-MRW, and rim volume), there were no significant differences in diagnostic capability (false discovery rate > 0.05 at 95% specificity). Conclusion 3D neuroretinal rim parameters (MDB, BMO-MRW, and rim volume) demonstrated better diagnostic capability for primary and secondary open angle glaucomas compared to 2D neuroretinal parameters (rim area, rim thickness). Compared to 2D RNFL thickness, 3D neuroretinal rim parameters have the same or better diagnostic capability. PMID:28234677

The influence of corneal astigmatism on retinal nerve fiber layer thickness and optic nerve head parameter measurements by spectral-domain optical coherence tomography

PubMed Central

2012-01-01

Background To evaluate the influence of corneal astigmatism (CA) on retinal nerve fiber layer (RNFL) thickness and optic nerve head(ONH) parameters measured with spectral-domain optical coherence tomography (OCT) in high myopes patients before refractive surgery. Methods Seventy eyes of 35 consecutive refractive surgery candidates were included in this study. The mean age of the subjects was 26.42 ± 6.95 years, the average CA was −1.17 diopters (D; SD 0.64; range −0.2 to-3.3D), All subjects in this study were WTR CA. 34 eyes were in the normal CA group with a mean CA was −0.67 ± 0.28D, 36 eyes were in the high CA group with an average CA of −1.65 ± 0.49D. All subjects underwent ophthalmic examination and imaging with the Cirrus HD OCT. Results No significant difference was noted in the average cup-to-disk ratio, vertical cup-to-disk ratio and cup volume (all P values > 0.05). Compared with the normal CA group, the high CA group had a larger disc area and rim area, thinner RNFL thickness in the temporal quadrant, and the superotemporal and inferotemporal peaks were farther to the temporal horizon (All P values < 0.05). There were no significant differences between the two groups in global average RNFL thickness, as well as superior, nasal and inferior quadrant RNFL thickness (all P values > 0.05). Conclusions The degree of with-the-rule CA should be considered when interpreting ONH parameters and peripapillary RNFL thickness measured by the Cirrus HD OCT. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1148475676881895 PMID:22621341

Detection of Progressive Retinal Nerve Fiber Layer Loss in Glaucoma Using Scanning Laser Polarimetry with Variable Corneal Compensation

PubMed Central

Medeiros, Felipe A.; Alencar, Luciana M.; Zangwill, Linda M.; Bowd, Christopher; Vizzeri, Gianmarco; Sample, Pamela A.; Weinreb, Robert N.

2010-01-01

Purpose To evaluate the ability of scanning laser polarimetry with variable corneal compensation to detect progressive retinal nerve fiber layer (RNFL) loss in glaucoma patients and patients suspected of having the disease. Methods This was an observational cohort study that included 335 eyes of 195 patients. Images were obtained annually with the GDx VCC scanning laser polarimeter, along with optic disc stereophotographs and standard automated perimetry (SAP) visual fields. The median follow-up time was 3.94 years. Progression was determined using commercial software for SAP and by masked assessment of optic disc stereophotographs performed by expert graders. Random coefficient models were used to evaluate the relationship between RNFL thickness measurements over time and progression as determined by SAP and/or stereophotographs. Results From the 335 eyes, 34 (10%) showed progression over time by stereophotographs and/or SAP. Average GDx VCC measurements decreased significantly over time for both progressors as well as non-progressors. However, the rate of decline was significantly higher in the progressing group (−0.70 μm/year) compared to the non-progressing group (−0.14 μm/year; P = 0.001). Black race and male sex were significantly associated with higher rates of RNFL loss during follow-up. Conclusions The GDx VCC scanning laser polarimeter was able to identify longitudinal RNFL loss in eyes that showed progression in optic disc stereophotographs and/or visual fields. These findings suggest that this technology could be useful to detect and monitor progressive disease in patients with established diagnosis of glaucoma or suspected of having the disease. PMID:19029038

Glaucomatous retinal nerve fiber layer thickness loss is associated with slower reaction times under a divided attention task.

PubMed

Tatham, Andrew J; Boer, Erwin R; Rosen, Peter N; Della Penna, Mauro; Meira-Freitas, Daniel; Weinreb, Robert N; Zangwill, Linda M; Medeiros, Felipe A

2014-11-01

To examine the relationship between glaucomatous structural damage and ability to divide attention during simulated driving. Cross-sectional observational study. Hamilton Glaucoma Center, University of California San Diego. Total of 158 subjects from the Diagnostic Innovations in Glaucoma Study, including 82 with glaucoma and 76 similarly aged controls. Ability to divide attention was investigated by measuring reaction times to peripheral stimuli (at low, medium, or high contrast) while concomitantly performing a central driving task (car following or curve negotiation). All subjects had standard automated perimetry (SAP) and optical coherence tomography was used to measure retinal nerve fiber layer (RNFL) thickness. Cognitive ability was assessed using the Montreal Cognitive Assessment and subjects completed a driving history questionnaire. Reaction times to the driving simulator divided attention task. The mean reaction times to the low-contrast stimulus were 1.05 s and 0.64 s in glaucoma and controls, respectively, during curve negotiation (P < .001), and 1.19 s and 0.77 s (P = .025), respectively, during car following. There was a nonlinear relationship between reaction times and RNFL thickness in the better eye. RNFL thickness remained significantly associated with reaction times even after adjusting for age, SAP mean deviation in the better eye, cognitive ability, and central driving task performance. Although worse SAP sensitivity was associated with worse ability to divide attention, RNFL thickness measurements provided additional information. Information from structural tests may improve our ability to determine which patients are likely to have problems performing daily activities, such as driving. Copyright © 2014 Elsevier Inc. All rights reserved.

Hypodense regions (holes) in the retinal nerve fiber layer in frequency-domain OCT scans of glaucoma patients and suspects.

PubMed

Xin, Daiyan; Talamini, Christine L; Raza, Ali S; de Moraes, Carlos Gustavo V; Greenstein, Vivienne C; Liebmann, Jeffrey M; Ritch, Robert; Hood, Donald C

2011-09-09

To better understand hypodense regions (holes) that appear in the retinal nerve fiber layer (RNFL) of frequency-domain optical coherence tomography (fdOCT) scans of patients with glaucoma and glaucoma suspects. Peripapillary circle (1.7-mm radius) and cube optic disc fdOCT scans were obtained on 208 eyes from 110 patients (57.4 ± 13.2 years) with glaucomatous optic neuropathy (GON) and 45 eyes of 45 controls (48.0 ± 12.6 years) with normal results of fundus examination. Holes in the RNFL were identified independently by two observers on the circle scans. Holes were found in 33 (16%) eyes of 28 (25%) patients; they were not found in any of the control eyes. Twenty-four eyes had more than one hole. Although some holes were relatively large, others were small. In general, the holes were located adjacent to blood vessels; only three eyes had isolated holes that were not adjacent to a vessel. The holes tended to be in the regions that are thickest in healthy controls and were associated with arcuate defects in patients. Holes were not seen in the center of the temporal disc region. They were more common in the superior (25 eyes) than in the inferior (15 eyes) disc. Of the 30 eyes with holes with reliable visual fields, seven were glaucoma suspect eyes with normal visual fields. The holes in the RNFL seen in patients with GON were probably due to a local loss of RNFL fibers and can occur in the eyes of glaucoma suspects with normal visual fields.

Influence of myelinated retinal nerve fibers on retinal vessel density measurement with AngioVue OCT angiography.

PubMed

Holló, Gábor

2016-12-01

Myelinated retinal nerve fibers (MRNF) represent an asymptomatic developmental anomaly in which myelin sheaths extend to a group of retinal nerve fibers along their intraocular portion. The additional volume of the myelin sheaths causes displacement of the axons toward the vitreous body. We investigated the effect of localized MRNF on peripapillary vessel density measurement results using optical coherence tomography (OCT) angiography. Peripapillary angioflow density measurements (PAFD, % of the analyzed retinal area) were made with the AngioVue OCT (Optovue Inc., Fremont, USA). In both cases, the predominant position of MRNF was inferonasal to the disk. Vessel density was clearly greater in the area of the MRNF than in the surrounding retina in the optic nerve head (ONH) level, but it was lower than in the surrounding retina in the retinal nerve fiber layer (RNFL) level. In the ONH level, PAFD was higher in the MRNF area than in the spatially corresponding superonasal area (Case 1: 64.6 vs. 57.6 %; Case 2: 65.8 vs. 56.3 %). In contrast, in the RNFL level, PAFD was lower in the MRNF area than in the corresponding superonasal area (Case 1: 60.1 vs. 65.4 %; Case 2: 46.5 vs. 58.5 %). Our cases show that the effect of MRNF on OCT angiography vessel density is different in the different measurement layers. Clinicians may separate decreased vessel density caused by anterior RNFL displacement in MRNF areas from that caused by nerve fiber damage in optic neuropathies by evaluating PAFD in both the ONH and RNFL levels.

Diagnostic Accuracy of Optical Coherence Tomography and Scanning Laser Tomography for Identifying Glaucoma in Myopic Eyes.

PubMed

Malik, Rizwan; Belliveau, Anne C; Sharpe, Glen P; Shuba, Lesya M; Chauhan, Balwantray C; Nicolela, Marcelo T

2016-06-01

Ruling out glaucoma in myopic eyes often poses a diagnostic challenge because of atypical optic disc morphology and visual field defects that can mimic glaucoma. We determined whether neuroretinal rim assessment based on Bruch's membrane opening (BMO), rather than conventional optic disc margin (DM)-based assessment or retinal nerve fiber layer (RNFL) thickness, yielded higher diagnostic accuracy in myopic patients with glaucoma. Case-control, cross-sectional study. Myopic patients with glaucoma (n = 56) and myopic normal controls (n = 74). Myopic subjects with refraction error greater than -2 diopters (D) (spherical equivalent) and typical myopic optic disc morphology, with and without glaucoma, were recruited from a glaucoma clinic and a local optometry practice. The final classification of myopic glaucoma or myopic control was based on consensus assessment by 3 clinicians of visual fields and optic disc photographs. Participants underwent imaging with confocal scanning laser tomography for measurement of DM rim area (DM-RA) and with spectral domain optical coherence tomography (SD OCT) for quantification of a BMO-based neuroretinal rim parameter, minimum rim width (BMO-MRW), and RNFL thickness. Sensitivity of DM-RA, BMO-MRW, and RNFL thickness at a fixed specificity of 90% and partial area under the curves (pAUCs) for global and sectoral parameters for specificities ≥90%. Sensitivities at 90% specificity were 30% for DM-RA and 71% for both BMO-MRW and RNFL thickness. The pAUC was higher for the BMO-MRW compared with DM-RA (P < 0.001), but similar to RNFL thickness (P > 0.5). Sectoral values of BMO-MRW tended to have a higher, but nonsignificant, pAUC across all sectors compared with RNFL thickness. Bruch's membrane opening MRW is more sensitive than DM-RA and similar to RNFL thickness for the identification of glaucoma in myopic eyes and offers a valuable diagnostic tool for patients with glaucoma with myopic optic discs. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Fibromyalgia Is Correlated with Retinal Nerve Fiber Layer Thinning.

PubMed

Garcia-Martin, Elena; Garcia-Campayo, Javier; Puebla-Guedea, Marta; Ascaso, Francisco J; Roca, Miguel; Gutierrez-Ruiz, Fernando; Vilades, Elisa; Polo, Vicente; Larrosa, Jose M; Pablo, Luis E; Satue, Maria

2016-01-01

To investigate whether fibromyalgia induces axonal damage in the optic nerve that can be detected using optical coherence tomography (OCT), as the retinal nerve fiber layer (RNFL) is atrophied in patients with fibromyalgia compared with controls. Fibromyalgia patients (n = 116) and age-matched healthy controls (n = 144) were included in this observational and prospective cohort study. All subjects underwent visual acuity measurement and structural analysis of the RNFL using two OCT devices (Cirrus and Spectralis). Fibromyalgia patients were evaluated according to Giesecke's fibromyalgia subgroups, the Fibromyalgia Impact Questionnaire (FIQ), and the European Quality of Life-5 Dimensions (EQ5D) scale. We compared the differences between fibromyalgia patients and controls, and analyzed the correlations between OCT measurements, disease duration, fibromyalgia subgroups, severity, and quality of life. The impact on quality of life in fibromyalgia subgroups and in patients with different disease severity was also analyzed. A significant decrease in the RNFL was detected in fibromyalgia patients compared with controls using the two OCT devices: Cirrus OCT ganglion cell layer analysis registered a significant decrease in the minimum thickness of the inner plexiform layer (74.99±16.63 vs 79.36±3.38 μm, respectively; p = 0.023), nasal inferior, temporal inferior and temporal superior sectors (p = 0.040; 0.011 and 0.046 respectively). The Glaucoma application of the Spectralis OCT revealed thinning in the nasal, temporal inferior and temporal superior sectors (p = 0.009, 0.006, and 0.002 respectively) of fibromyalgia patients and the Axonal application in all sectors, except the nasal superior and temporal sectors. The odds ratio (OR) to estimate the size effect of FM in RNFL thickness was 1.39. RNFL atrophy was detected in patients with FIQ scores <60 (patients in early disease stages) compared with controls in the temporal inferior sector (78.74±17.75 vs 81.65±3.61; p = 0.020) and the temporal superior sector (78.20±14.50 vs 80.74±3.88; p = 0.039) with Cirrus OCT; in the temporal inferior sector (145.85±24.32 vs 150.18±19.71; p = 0.012) and temporal superior sector (131.54±20.53 vs 138.13±16.67; p = 0.002) with the Glaucoma application of the Spectralis OCT; and in all sectors, except the average, nasal superior, and temporal sectors, and parameters with the Axonal application of the Spectralis OCT. Temporal inferior RNFL thickness was significantly reduced in patients with severe fibromyalgia (FIQ≥60) compared with patients with mild fibromyalgia (FIQ<60; 145.85±24.32 vs 138.99±18.09 μm, respectively; 145.43±13.21 vs 139.85±13.09 μm, p = 0.032 with the Glaucoma application and p = 0.021 with the Axonal application). The subgroup with biologic fibromyalgia exhibited significant thinning in the temporal inferior and superior sectors (115.17±20.82 μm and 117.05±24.19 μm, respectively) compared with the depressive (130.83±22.97 μm and 127.71±26.10 μm, respectively) and atypical (128.60±26.54 μm and 125.55±23.65 μm, respectively) subgroups (p = 0.005 and 0.001 respectively). Fibromyalgia causes subclinical axonal damage in the RNFL that can be detected using innocuous and non-invasive OCT, even in the early disease stages. The impact on the RNFL in the temporal sectors is greater in patients with biologic fibromyalgia, suggesting the presence of neurodegenerative processes in this subgroup of patients with fibromyalgia.

Fibromyalgia Is Correlated with Retinal Nerve Fiber Layer Thinning

PubMed Central

Garcia-Martin, Elena; Garcia-Campayo, Javier; Puebla-Guedea, Marta; Ascaso, Francisco J.; Roca, Miguel; Gutierrez-Ruiz, Fernando; Vilades, Elisa; Polo, Vicente; Larrosa, Jose M.; Pablo, Luis E.; Satue, Maria

2016-01-01

Objective To investigate whether fibromyalgia induces axonal damage in the optic nerve that can be detected using optical coherence tomography (OCT), as the retinal nerve fiber layer (RNFL) is atrophied in patients with fibromyalgia compared with controls. Methods Fibromyalgia patients (n = 116) and age-matched healthy controls (n = 144) were included in this observational and prospective cohort study. All subjects underwent visual acuity measurement and structural analysis of the RNFL using two OCT devices (Cirrus and Spectralis). Fibromyalgia patients were evaluated according to Giesecke’s fibromyalgia subgroups, the Fibromyalgia Impact Questionnaire (FIQ), and the European Quality of Life-5 Dimensions (EQ5D) scale. We compared the differences between fibromyalgia patients and controls, and analyzed the correlations between OCT measurements, disease duration, fibromyalgia subgroups, severity, and quality of life. The impact on quality of life in fibromyalgia subgroups and in patients with different disease severity was also analyzed. Results A significant decrease in the RNFL was detected in fibromyalgia patients compared with controls using the two OCT devices: Cirrus OCT ganglion cell layer analysis registered a significant decrease in the minimum thickness of the inner plexiform layer (74.99±16.63 vs 79.36±3.38 μm, respectively; p = 0.023), nasal inferior, temporal inferior and temporal superior sectors (p = 0.040; 0.011 and 0.046 respectively). The Glaucoma application of the Spectralis OCT revealed thinning in the nasal, temporal inferior and temporal superior sectors (p = 0.009, 0.006, and 0.002 respectively) of fibromyalgia patients and the Axonal application in all sectors, except the nasal superior and temporal sectors. The odds ratio (OR) to estimate the size effect of FM in RNFL thickness was 1.39. RNFL atrophy was detected in patients with FIQ scores <60 (patients in early disease stages) compared with controls in the temporal inferior sector (78.74±17.75 vs 81.65±3.61; p = 0.020) and the temporal superior sector (78.20±14.50 vs 80.74±3.88; p = 0.039) with Cirrus OCT; in the temporal inferior sector (145.85±24.32 vs 150.18±19.71; p = 0.012) and temporal superior sector (131.54±20.53 vs 138.13±16.67; p = 0.002) with the Glaucoma application of the Spectralis OCT; and in all sectors, except the average, nasal superior, and temporal sectors, and parameters with the Axonal application of the Spectralis OCT. Temporal inferior RNFL thickness was significantly reduced in patients with severe fibromyalgia (FIQ≥60) compared with patients with mild fibromyalgia (FIQ<60; 145.85±24.32 vs 138.99±18.09 μm, respectively; 145.43±13.21 vs 139.85±13.09 μm, p = 0.032 with the Glaucoma application and p = 0.021 with the Axonal application). The subgroup with biologic fibromyalgia exhibited significant thinning in the temporal inferior and superior sectors (115.17±20.82 μm and 117.05±24.19 μm, respectively) compared with the depressive (130.83±22.97 μm and 127.71±26.10 μm, respectively) and atypical (128.60±26.54 μm and 125.55±23.65 μm, respectively) subgroups (p = 0.005 and 0.001 respectively). Conclusions Fibromyalgia causes subclinical axonal damage in the RNFL that can be detected using innocuous and non-invasive OCT, even in the early disease stages. The impact on the RNFL in the temporal sectors is greater in patients with biologic fibromyalgia, suggesting the presence of neurodegenerative processes in this subgroup of patients with fibromyalgia. PMID:27584145

Fourier-domain optical coherence tomography and adaptive optics reveal nerve fiber layer loss and photoreceptor changes in a patient with optic nerve drusen.

PubMed

Choi, Stacey S; Zawadzki, Robert J; Greiner, Mark A; Werner, John S; Keltner, John L

2008-06-01

New technology allows more precise definition of structural alterations of all retinal layers although it has not been used previously in cases of optic disc drusen. Using Stratus and Fourier domain (FD) optical coherence tomography (OCT) and adaptive optics (AO) through a flood-illuminated fundus camera, we studied the retinas of a patient with long-standing optic disc drusen and acute visual loss at high altitude attributed to ischemic optic neuropathy. Stratus OCT and FD-OCT confirmed severe thinning of the retinal nerve fiber layer (RNFL). FD-OCT revealed disturbances in the photoreceptor layer heretofore not described in optic disc drusen patients. AO confirmed the FD-OCT findings in the photoreceptor layer and also showed reduced cone density at retinal locations associated with reduced visual sensitivity. Based on this study, changes occur not only in the RNFL but also in the photoreceptor layer in optic nerve drusen complicated by ischemic optic neuropathy. This is the first reported application of FD-OCT and the AO to this condition. Such new imaging technology may in the future allow monitoring of disease progression more precisely and accurately.

Association of Maternal Smoking During Pregnancy and Birth Weight With Retinal Nerve Fiber Layer Thickness in Children Aged 11 or 12 Years: The Copenhagen Child Cohort 2000 Eye Study.

PubMed

Ashina, Håkan; Li, Xiao Qiang; Olsen, Else Marie; Skovgaard, Anne Mette; Larsen, Michael; Munch, Inger Christine

2017-04-01

Both maternal smoking during pregnancy and low birth weight have been implicated in impaired development of the retina. To investigate the associations of maternal smoking during pregnancy and low birth weight with retinal nerve fiber layer (RNFL) thickness in preadolescent children. The Copenhagen Child Cohort 2000 Eye Study is a prospective, population-based, birth cohort study that included all children (n = 6090) born in 2000 in Copenhagen, Denmark. Maternal smoking data were collected through parental interviews. Birth weight, pregnancy, and medical history data were obtained from the Danish Medical Birth Registry. As a follow-up, the study performed eye examinations on 1406 of these children from May 1, 2011, to October 31, 2012, when the children were aged 11 or 12 years. The participants were predominantly (1296 [92.4%]) of European descent. Study data were analyzed from June 1, 2016, to October 1, 2016. Peripapillary RNFL thickness measured using optical coherence tomography at the 11- or 12-year examination. Of the 1406 children in the study, 1323 were included in the analysis (mean [SD] age was 11.7 [0.4] years; 633 [47.8%] were boys and 690 [52.2%] were girls). The mean (SD) RNFL thickness was 104 (9.6) μm. In 227 children whose mothers had smoked during pregnancy, the peripapillary RNFL was 5.7 μm (95% CI, 4.3-7.1 μm; P < .001) thinner than in children whose mothers had not smoked after correction for age, sex, birth weight, height, body weight, Tanner stage of pubertal development, axial length, and spherical equivalent refractive error. In low-birth-weight children (<2500 g), the RNFL was 3.5 μm (95% CI, 0.6-6.3 μm; P = .02) thinner than in normal-birth-weight children after adjustment for all variables. Exposure to maternal smoking during uterine life and low birth weight were independently associated with having a thinner RNFL at age 11 or 12 years. These observations support previous findings that intrauterine and perinatal factors can have long-lasting effects on the retina and the optic nerve. The results of this study add evidence to existing recommendations to avoid smoking during pregnancy and support measures that promote maternal and fetal health.

Macular Ganglion Cell Imaging Study: Covariate Effects on the Spectral Domain Optical Coherence Tomography for Glaucoma Diagnosis

PubMed Central

Jeong, Jae Hoon; Choi, Yun Jeong; Park, Ki Ho; Kim, Dong Myung

2016-01-01

Purpose To evaluate the effect of multiple covariates on the diagnostic performance of the Cirrus high-definition optical coherence tomography (HD-OCT) for glaucoma detection. Methods A prospective case-control study was performed and included 173 recently diagnosed glaucoma patients and 63 unaffected individuals from the Macular Ganglion Cell Imaging Study. Regression analysis of receiver operating characteristic were conducted to evaluate the influence of age, spherical equivalent, axial length, optic disc size, and visual field index on the macular ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (RNFL) measurements. Results Disease severity, as measured by visual field index, had a significant effect on the diagnostic performance of all Cirrus HD-OCT parameters. Age, axial length and optic disc size were significantly associated with diagnostic accuracy of average peripapillary RNFL thickness, whereas axial length had a significant effect on the diagnostic accuracy of average GCIPL thickness. Conclusions Diagnostic performance of the Cirrus HD-OCT may be more accurate in the advanced stages of glaucoma than at earlier stages. A smaller optic disc size was significantly associated with improved the diagnostic ability of average RNFL thickness measurements; however, GCIPL thickness may be less affected by age and optic disc size. PMID:27490718

Asymmetry of Peak Thicknesses between the Superior and Inferior Retinal Nerve Fiber Layers for Early Glaucoma Detection: A Simple Screening Method.

PubMed

Bae, Hyoung Won; Lee, Sang Yeop; Kim, Sangah; Park, Chan Keum; Lee, Kwanghyun; Kim, Chan Yun; Seong, Gong Je

2018-01-01

To assess whether the asymmetry in the peripapillary retinal nerve fiber layer (pRNFL) thickness between superior and inferior hemispheres on optical coherence tomography (OCT) is useful for early detection of glaucoma. The patient population consisted of Training set (a total of 60 subjects with early glaucoma and 59 normal subjects) and Validation set (30 subjects with early glaucoma and 30 normal subjects). Two kinds of ratios were employed to measure the asymmetry between the superior and inferior pRNFL thickness using OCT. One was the ratio of the superior to inferior peak thicknesses (peak pRNFL thickness ratio; PTR), and the other was the ratio of the superior to inferior average thickness (average pRNFL thickness ratio; ATR). The diagnostic abilities of the PTR and ATR were compared to the color code classification in OCT. Using the optimal cut-off values of the PTR and ATR obtained from the Training set, the two ratios were independently validated for diagnostic capability. For the Training set, the sensitivities/specificities of the PTR, ATR, quadrants color code classification, and clock-hour color code classification were 81.7%/93.2%, 71.7%/74.6%, 75.0%/93.2%, and 75.0%/79.7%, respectively. The PTR showed a better diagnostic performance for early glaucoma detection than the ATR and the clock-hour color code classification in terms of areas under the receiver operating characteristic curves (AUCs) (0.898, 0.765, and 0.773, respectively). For the Validation set, the PTR also showed the best sensitivity and AUC. The PTR is a simple method with considerable diagnostic ability for early glaucoma detection. It can, therefore, be widely used as a new screening method for early glaucoma. © Copyright: Yonsei University College of Medicine 2018

Baseline OCT Measurements in the Idiopathic Intracranial Hypertension Treatment Trial, Part I: Quality Control, Comparisons, and Variability

PubMed Central

2014-01-01

Purpose. Optical coherence tomography (OCT) has been used to investigate papilledema in single-site, mostly retrospective studies. We investigated whether spectral-domain OCT (SD-OCT), which provides thickness and volume measurements of the optic nerve head and retina, could reliably demonstrate structural changes due to papilledema in a prospective multisite clinical trial setting. Methods. At entry, 126 subjects in the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) with mild visual field loss had optic disc and macular scans, using the Cirrus SD-OCT. Images were analyzed by using the proprietary commercial and custom 3D-segmentation algorithms to calculate retinal nerve fiber layer (RNFL), total retinal thickness (TRT), optic nerve head volume (ONHV), and retinal ganglion cell layer (GCL) thickness. We evaluated variability, with interocular comparison and correlation between results for both methods. Results. The average RNFL thickness > 95% of normal controls in 90% of eyes and the RNFL, TRT, ONH height, and ONHV showed strong (r > 0.8) correlations for interocular comparisons. Variability for repeated testing of OCT parameters was low for both methods and intraclass correlations > 0.9 except for the proprietary GCL thickness. The proprietary algorithm–derived RNFL, TRT, and GCL thickness measurements had failure rates of 10%, 16%, and 20% for all eyes respectively, which were uncommon with 3D-segmentation–derived measurements. Only 7% of eyes had GCL thinning that was less than fifth percentile of normal age-matched control eyes by both methods. Conclusions. Spectral-domain OCT provides reliable continuous variables and quantified assessment of structural alterations due to papilledema. (ClinicalTrials.gov number, NCT01003639.) PMID:25370510

Evaluation of possible factors affecting contrast sensitivity function in patients with primary Sjögren's syndrome.

PubMed

Arikan, Sedat; Gokmen, Ferhat; Comez, Arzu Taskiran; Gencer, Baran; Kara, Selcuk; Akbal, Ayla

2015-01-01

The contrast sensitivity (CS) function in patients with primary Sjögren's syndrome (pSS) may be impaired either frequently as a result of dry eye diseases or rarely as a result of optic neuropathy. In this study, we aimed to evaluate the CS function in pSS patients as well as to assess corneal aberrations and thickness of the peripapillary retinal nerve fiber layer (pRNFL). Fourteen eyes of 14 pSS patients (pSS group) and 14 eyes of 14 healthy participants (control group) were subjected to assessment of CS at the spatial frequencies of 1.5, 3.0, 6.0, 12, and 18 cycles/degree (cpd) using a functional visual acuity contrast test (FACT); measurement of corneal high-order aberrations (HOAs) in terms of coma-like, spherical-like, and total HOAs using Scheimpflug corneal topography; and measurement of the thickness of both the macular ganglion cell-inner plexiform layer (mGCIPL) and pRNFL in all quadrants using optical coherence tomography. None of the participants were under treatment with artificial tears. The results of the CS test did not differ between the 2 groups at all spatial frequencies (p>0.05). In addition, there were no statistically significant differences between the 2 groups in terms of corneal HOAs (p>0.05) and thickness of mGCIPL (p>0.05). However, among all quadrants, only the inferior quadrant of pRNFL in pSS patients was statistically significantly thinner than that in the healthy participants (p=0.04). The CS function in pSS patients can be maintained with normal thickness of both pRNFL and mGCIPL and with lack of increased corneal HOAs, which may be present even in the absence of artificial tear usage.

Spectral Domain Optical Coherence Tomography in Glaucoma: Qualitative and Quantitative Analysis of the Optic Nerve Head and Retinal Nerve Fiber Layer (An AOS Thesis)

PubMed Central

Chen, Teresa C.

2009-01-01

Purpose: To demonstrate that video-rate spectral domain optical coherence tomography (SDOCT) can qualitatively and quantitatively evaluate optic nerve head (ONH) and retinal nerve fiber layer (RNFL) glaucomatous structural changes. To correlate quantitative SDOCT parameters with disc photography and visual fields. Methods: SDOCT images from 4 glaucoma eyes (4 patients) with varying stages of open-angle glaucoma (ie, early, moderate, late) were qualitatively contrasted with 2 age-matched normal eyes (2 patients). Of 61 other consecutive patients recruited in an institutional setting, 53 eyes (33 patients) met inclusion/exclusion criteria for quantitative studies. Images were obtained using two experimental SDOCT systems, one utilizing a superluminescent diode and the other a titanium:sapphire laser source, with axial resolutions of about 6 μm and 3 μm, respectively. Results: Classic glaucomatous ONH and RNFL structural changes were seen in SDOCT images. An SDOCT reference plane 139 μm above the retinal pigment epithelium yielded cup-disc ratios that best correlated with masked physician disc photography cup-disc ratio assessments. The minimum distance band, a novel SDOCT neuroretinal rim parameter, showed good correlation with physician cup-disc ratio assessments, visual field mean deviation, and pattern standard deviation (P values range, .0003–.024). RNFL and retinal thickness maps correlated well with disc photography and visual field testing. Conclusions: To our knowledge, this thesis presents the first comprehensive qualitative and quantitative evaluation of SDOCT images of the ONH and RNFL in glaucoma. This pilot study provides basis for developing more automated quantitative SDOCT-specific glaucoma algorithms needed for future prospective multicenter national trials. PMID:20126502

A framework for comparing structural and functional measures of glaucomatous damage

PubMed Central

Hood, Donald C.; Kardon, Randy H.

2007-01-01

While it is often said that structural damage due to glaucoma precedes functional damage, it is not always clear what this statement means. This review has two purposes: first, to show that a simple linear relationship describes the data relating a particular functional test (standard automated perimetry (SAP)) to a particular structural test (optical coherence tomography (OCT)); and, second, to propose a general framework for relating structural and functional damage, and for evaluating if one precedes the other. The specific functional and structural tests employed are described in Section 2. To compare SAP sensitivity loss to loss of the retinal nerve fiber layer (RNFL) requires a map that relates local field regions to local regions of the optic disc as described in Section 3. When RNFL thickness in the superior and inferior arcuate sectors of the disc are plotted against SAP sensitivity loss (dB units) in the corresponding arcuate regions of the visual field, RNFL thickness becomes asymptotic for sensitivity losses greater than about 10 dB. These data are well described by a simple linear model presented in Section 4. The model assumes that the RNFL thickness measured with OCT has two components. One component is the axons of the retinal ganglion cells and the other, the residual, is everything else (e.g. glial cells, blood vessels). The axon portion is assumed to decrease in a linear fashion with losses in SAP sensitivity (in linear units); the residual portion is assumed to remain constant. Based upon severe SAP losses in anterior ischemic optic neuropathy (AION), the residual RNFL thickness in the arcuate regions is, on average, about one-third of the premorbid (normal) thickness of that region. The model also predicts that, to a first approximation, SAP sensitivity in control subjects does not depend upon RNFL thickness. The data (Section 6) are, in general, consistent with this prediction showing a very weak correlation between RNFL thickness and SAP sensitivity. In Section 7, the model is used to estimate the proportion of patients showing statistical abnormalities (worse than the 5th percentile) on the OCT RNFL test before they show abnormalities on the 24-2 SAP field test. Ignoring measurement error, the patients with a relatively thick RNFL, when healthy, will be more likely to show significant SAP sensitivity loss before statistically significant OCT RNFL loss, while the reverse will be true for those who start with an average or a relatively thin RNFL when healthy. Thus, it is important to understand the implications of the wide variation in RNFL thickness among control subjects. Section 8 describes two of the factors contributing to this variation, variations in the position of blood vessels and variations in the mapping of field regions to disc sectors. Finally, in Sections 7 and 9, the findings are related to the general debate in the literature about the relationship between structural and functional glaucomatous damage and a framework is proposed for understanding what is meant by the question, ‘Does structural damage precede functional damage in glaucoma?’ An emphasis is placed upon the need to distinguish between “statistical” and “relational” meanings of this question. PMID:17889587

The relationship between contrast sensitivity and retinal nerve fiber layer thickness in patients with glaucoma.

PubMed

Amanullah, Sarah; Okudolo, Joseph; Rahmatnejad, Kamran; Lin, Shuai-Chun; Wizov, Sheryl S; Manzi Muhire, Remy S; Hark, Lisa A; Zheng, Cindy X; Zhan, Tingting; Spaeth, George L

2017-12-01

To evaluate the correlation between contrast sensitivity (CS) and retinal nerve fiber layer (RNFL) in different areas of vision. This report is a sub-analysis of a prospective, observational cohort study investigating changes in performance-based assessment, vision-related quality of life, and clinical measures in patients with moderate to advanced glaucoma. The study included 161 participants with at least a 2-year history of glaucoma who underwent annual testing for 4 years. Contrast sensitivity was measured using the Spaeth/Richman contrast sensitivity (SPARCS) test, while RNFL thickness (RNFLT) was measured using Cirrus optical coherence tomography (OCT). Statistical analyses were performed to determine correlations between CS and RNFLT; the correlations were calculated for each annual visit, totaling four correlation coefficients for each patient over the course of 4 years. The SPARCS score in the left upper area of vision correlated the most strongly with the RNFLT of the inferior quadrant for both eyes at each annual visit, specifically in the seven o'clock sector for the left eye and the six o'clock sector for the right eye (p < 0.05). There were no discernible trends for the correlations between the other areas of CS and RNFL quadrants or clock hours over the 4 years of the study. Linear regression between the SPARCS total score and average RNFLT showed a significant direct correlation at each visit (p < 0.01). Contrast sensitivity in the left upper area of vision for both eyes correlated most strongly with the thickness of the inferior quadrant of the RNFL. These fibers project to the temporal portion of the right occipital lobe, implying a potential center for contrast perception in this area. The longitudinal nature of the study suggests that CS may be a predictive tool for changes in RNFL in patients with glaucoma. Despite this finding, retinal damage and its relationship to CS was diffuse. In addition, SPARCS was shown to predict RNFLT. Further research is warranted to understand how CS can be used as a tool in the clinical setting.

Comparison of retinal nerve fiber layer thickness in vivo and axonal transport after chronic intraocular pressure elevation in young versus older rats.

PubMed

Abbott, Carla J; Choe, Tiffany E; Burgoyne, Claude F; Cull, Grant; Wang, Lin; Fortune, Brad

2014-01-01

To compare in young and old rats longitudinal measurements of retinal nerve fiber layer thickness (RNFLT) and axonal transport 3-weeks after chronic IOP elevation. IOP was elevated unilaterally in 2- and 9.5-month-old Brown-Norway rats by intracameral injections of magnetic microbeads. RNFLT was measured by spectral domain optical coherence tomography. Anterograde axonal transport was assessed from confocal scanning laser ophthalmolscopy of superior colliculi (SC) after bilateral intravitreal injections of cholera toxin-B-488. Optic nerve sections were graded for damage. Mean IOP was elevated in both groups (young 37, old 38 mmHg, p = 0.95). RNFL in young rats exhibited 10% thickening at 1-week (50.9±8.1 µm, p<0.05) vs. baseline (46.4±2.4 µm), then 7% thinning at 2-weeks (43.0±7.2 µm, p>0.05) and 3-weeks (43.5±4.4 µm, p>0.05), representing 20% loss of dynamic range. RNFLT in old rats showed no significant change at 1-week (44.9±4.1 µm) vs. baseline (49.2±5.3 µm), but progression to 22% thinning at 2-weeks (38.0±3.7 µm, p<0.01) and 3-weeks (40.0±6.6 µm, p<0.05), representing 59% loss of dynamic range. Relative SC fluorescence intensity was reduced in both groups (p<0.001), representing 77-80% loss of dynamic range and a severe transport deficit. Optic nerves showed 75-95% damage (p<0.001). There was greater RNFL thinning in old rats (p<0.05), despite equivalent IOP insult, transport deficit and nerve damage between age groups (all p>0.05). Chronic IOP elevation resulted in severely disrupted axonal transport and optic nerve axon damage in all rats, associated with mild RNFL loss in young rats but a moderate RNFL loss in old rats despite the similar IOP insult. Hence, the glaucomatous injury response within the RNFL depends on age.

Relating retinal nerve fiber thickness to behavioral sensitivity in patients with glaucoma: application of a linear model.

PubMed

Hood, Donald C

2007-05-01

Glaucoma causes damage to the retinal ganglion cells and their axons, and this damage can be detected with both structural and functional tests. The purpose of this study was to better understand the relationship between a structural measure of retinal nerve fiber layer (RNFL) and the most common functional test, behavioral sensitivity with static automated perimetry (SAP). First, a linear model, previously shown to describe the relationship between local visual evoked potentials and SAP sensitivity, was modified to predict the change in RNFL as measured by optical coherence tomography. Second, previous work by others was shown to be consistent with this model.

Diagnostic Capability of Spectral Domain Optical Coherence Tomography for Glaucoma

PubMed Central

Wu, Huijuan; de Boer, Johannes F.; Chen, Teresa C.

2012-01-01

Purpose To determine the diagnostic capability of spectral domain optical coherence tomography (OCT) in glaucoma patients with visual field (VF) defects. Design Prospective, cross-sectional study. Methods Setting Participants were recruited from a university hospital clinic. Study Population One eye of 85 normal subjects and 61 glaucoma patients [with average VF mean deviation (MD) of -9.61 ± 8.76 dB] were randomly selected for the study. A subgroup of the glaucoma patients with early VF defects was calculated separately. Observation Procedures Spectralis OCT circular scans were performed to obtain peripapillary retinal nerve fiber layer (RNFL) thicknesses. The RNFL diagnostic parameters based on the normative database were used alone or in combination for identifying glaucomatous RNFL thinning. Main Outcome Measures To evaluate diagnostic performance, calculations included areas under the receiver operating characteristic curve (AROC), sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio. Results Overall RNFL thickness had the highest AROC value (0.952 for all patients, 0.895 for the early glaucoma subgroup). For all patients, the highest sensitivity (98.4%, CI 96.3-100%) was achieved by using two criteria: ≥1 RNFL sectors being abnormal at the < 5% level, and overall classification of borderline or outside normal limits, with specificities of 88.9% (CI 84.0-94.0%) and 87.1% (CI 81.6-92.5%) respectively for these two criteria. Conclusions Statistical parameters for evaluating the diagnostic performance of the Spectralis spectral domain OCT were good for early perimetric glaucoma and excellent for moderately-advanced perimetric glaucoma. PMID:22265147

Customizing Perimetric Locations Based on En Face Images of Retinal Nerve Fiber Bundles With Glaucomatous Damage

PubMed Central

Alluwimi, Muhammed S.; Swanson, William H.; Malinovsky, Victor E.; King, Brett J.

2018-01-01

Purpose Prior studies suggested the use of customized perimetric locations in glaucoma; these studies were limited by imaging only the superficial depths of the retinal nerve fiber layer (RNFL) and by prolonged perimetric testing. We aimed to develop a rapid perimetric test guided by high-resolution images of RNFL bundles. Methods We recruited 10 patients with glaucoma, ages 56 to 80 years, median 68 years, and 10 controls, ages 55 to 77 years, median 68 years. The patients were selected based on discrepancies between locations of glaucomatous damage for perimetric and structural measures. Montaging was used to produce optical coherence tomography en face images of the RNFL covering much of the 24-2 grid locations. In experiment 1, we presented the Goldmann size III stimulus at preselected retinal locations of glaucomatous damage, using just two contrasts. In experiment 2, we developed an elongated sinusoidal stimulus, aligned within the defect, to measure contrast sensitivities; abnormalities were defined based on lower 95% reference limits derived from the controls. Results The percentage of predicted locations where size III was not seen at 28 dB ranged from 16% to 80%, with a median of 48%. Contrast sensitivity for the sinusoidal stimulus was below the 95% reference range for 37 of 44 stimuli aligned within the defects. Conclusions We developed methods for rapid perimetric testing guided by en face images of the RNFL bundles in patients with glaucoma. Results indicated ganglion cell damage under all of the visible RNFL defects. Translational Relevance Customized perimetric locations have potential to improve clinical assessment of glaucoma. PMID:29576929

Initial Arcuate Defects within the Central 10 Degrees in Glaucoma

PubMed Central

Raza, Ali S.; de Moraes, Carlos Gustavo V.; Odel, Jeffrey G.; Greenstein, Vivienne C.; Liebmann, Jeffrey M.; Ritch, Robert

2011-01-01

Purpose. To better understand the relationship between the spatial patterns of functional (visual field [VF] loss) and structural (axon loss) abnormalities in patients with glaucomatous arcuate defects largely confined to the central 10° on achromatic perimetry. Methods. Eleven eyes (9 patients) with arcuate glaucomatous VF defects largely confined to the macula were selected from a larger group of patients with both 10-2 and 24-2 VF tests. Eyes were included if their 10-2 VF had an arcuate defect and if the 24-2 test was normal outside the central 10° (i.e., did not have a cluster of three contiguous points within a hemifield). For the structural analysis, plots of retinal nerve fiber layer (RNFL) thickness of the macula were obtained with frequency-domain optical coherence tomography (fdOCT). The optic disc locations of the RNFL defects were identified on peripapillary fdOCT scans. Results. The VF arcuate defects extended to within 1° of fixation on the 10-2 test and were present in the superior hemifield in 10 of the 11 eyes. The arcuate RNFL damage, seen in the macular fdOCT scans of all 11 eyes, involved the temporal and inferior temporal portions of the disc on the peripapillary scans. Conclusions. Glaucomatous arcuate defects of the macula's RNFL meet the disc temporal to the peak of the main arcuate bundles and produce a range of macular VF defects from clear arcuate scotomas to a papillofoveal horizontal step (“pistol barrel scotoma”). If RGC displacement is taken into consideration, the RNFL and VF defects can be compared directly. PMID:20881293

Differences between Non-arteritic Anterior Ischemic Optic Neuropathy and Open Angle Glaucoma with Altitudinal Visual Field Defect.

PubMed

Han, Sangyoun; Jung, Jong Jin; Kim, Ungsoo Samuel

2015-12-01

To investigate the differences in retinal nerve fiber layer (RNFL) change and optic nerve head parameters between non-arteritic anterior ischemic optic neuropathy (NAION) and open angle glaucoma (OAG) with altitudinal visual field defect. Seventeen NAION patients and 26 OAG patients were enrolled prospectively. The standard visual field indices (mean deviation, pattern standard deviation) were obtained from the Humphrey visual field test and differences between the two groups were analyzed. Cirrus HD-OCT parameters were used, including optic disc head analysis, average RNFL thickness, and RNFL thickness of each quadrant. The mean deviation and pattern standard deviation were not significantly different between the groups. In the affected eye, although the disc area was similar between the two groups (2.00 ± 0.32 and 1.99 ± 0.33 mm(2), p = 0.586), the rim area of the OAG group was smaller than that of the NAION group (1.26 ± 0.56 and 0.61 ± 0.15 mm(2), respectively, p < 0.001). RNFL asymmetry was not different between the two groups (p = 0.265), but the inferior RNFL thickness of both the affected and unaffected eyes were less in the OAG group than in the NAION group. In the analysis of optic disc morphology, both affected and unaffected eyes showed significant differences between two groups. To differentiate NAION from OAG in eyes with altitudinal visual field defects, optic disc head analysis of not only the affected eye, but also the unaffected eye, by using spectral domain optical coherence tomography may be helpful.

Increased serum level of homocysteine correlates with retinal nerve fiber layer thinning in diabetic retinopathy

PubMed Central

Srivastav, Khushboo; Mahdi, Abbas A.; Shukla, Rajendra K.; Meyer, Carsten H.; Akduman, Levent; Khanna, Vinay K.

2016-01-01

Purpose To study the correlation between serum levels of vitamin B12, folic acid, and homocysteine and the severity of diabetic retinopathy and the correlation with retinal nerve fiber layer (RNFL) thinning on spectral domain optical coherence tomography (SD-OCT). Methods In a tertiary care center–based prospective cross-sectional study, 60 consecutive cases and 20 healthy controls in the age group of 40–65 years were included. The eyes of the cases were divided into three groups according to Early Treatment Diabetic Retinopathy Study (ETDRS) classification: diabetes mellitus without retinopathy (n = 20), non-proliferative diabetic retinopathy with macular edema (n = 20), and proliferative diabetic retinopathy with macular edema (n = 20). The serum levels of vitamin B12 and folic acid were measured using a standard protocol. The serum homocysteine assay was performed using an enzyme-linked immunosorbent assay (ELISA) kit. Average RNFL thickness was measured using SD-OCT. Statistical analysis was used to assess the correlations between the study variables. Results Increased severity of diabetic retinopathy was found to correlate with an increase in the serum levels of homocysteine (F = 53.79; p<0.001). The mean serum levels of vitamin B12 and folic acid were found to be within the normal reference range. A positive correlation was found between retinal nerve fiber layer thinning and serum levels of homocysteine (p<0.001). Conclusions This study, for the first time, demonstrated a correlation between increased homocysteine with a decrease in RNFL thickness and increased severity of diabetic retinopathy. PMID:27994434

Structural characteristics of the acquired optic disc pit and the rate of progressive retinal nerve fiber layer thinning in primary open-angle glaucoma.

PubMed

Lee, Seung Hyen; Lee, Eun Ji; Kim, Tae-Woo

2015-10-01

The optic disc pit (ODP) has been considered a region of localized susceptibility to the damage of glaucoma. To determine whether the rate of retinal nerve fiber layer (RNFL) thinning differs according to the presence and structural characteristics of an ODP in primary open-angle glaucoma. We performed a prospective case-control study that included 163 eyes with primary open-angle glaucoma (83 with an ODP and 80 without an ODP) from Glaucoma Clinic of Seoul National University Bundang Hospital. Participants were enrolled from the ongoing Investigating Glaucoma Progression Study from January 1, 2012, through May 31, 2014. Mean (SD) follow-up was 3.32 (0.49) years (through May 31, 2014). Optic nerve heads underwent swept-source optical coherence tomography (OCT) to determine the presence of focal lamina cribrosa alteration and its structural characteristics. Eyes with and without photographic ODPs and corresponding microscopic laminar alterations were assigned to the ODP and non-ODP groups, respectively. The rates of progressive thinning of global and 6 sectoral spectral-domain OCT RNFL thicknesses were determined by linear regression and compared between the 2 groups. We used a general linear model to determine the factors associated with the rate of RNFL thinning; data obtained from September 21, 2009, through May 31, 2014, were used to calculate the rate of RNFL thinning. The relationship between the presence and structural characteristics of ODPs and the rate of progressive OCT RNFL thinning. Thinning of the RNFL was faster in the ODP group than in the non-ODP group in the global (mean [SD], -1.44 [1.31] vs -0.93 [1.10] [95% CI, -0.97 to -0.19] μm/y; P = .008), temporoinferior (mean [SD], -4.17 [4.15] vs -1.97 [3.26] [95% CI, -3.36 to -1.04] μm/y; P < .001), and temporal (mean [SD], -1.92 [2.62] vs -0.89 [1.62] [95% CI, -1.70 to -0.35] μm/y; P = .003) sectors. The rate of RNFL thinning was maximum in the temporoinferior sector (mean [SD], -4.17 [4.15] μm/y) and corresponded to the frequency distribution of ODPs. Regression analysis revealed that faster global RNFL thinning was related to a higher untreated intraocular pressure (β = -0.07; 95% CI, -0.11 to -0.03; P = .001), episodes of disc hemorrhage (β = -0.74; 95% CI, -1.79 to 0.31; P = .003), the presence of β-zone parapapillary atrophy (β = -0.47; 95% CI, -1.13 to 0.20; P = .02), and the presence of ODPs (β = -0.41; 95% CI, -1.14 to 0.32; P = .02). The maximum rate of RNFL thinning was associated with higher untreated intraocular pressure (β = -0.24; 95% CI, -0.35 to -0.13; P < .001), disc hemorrhage (β = -1.54; 95% CI, -2.88 to -0.19; P < .001), and the presence (β = -1.04; 95% CI, -2.14 to 0.07; P = .004), far-peripheral location (β = -1.75; 95% CI, -3.05 to -0.46; P = .008), and partial-thickness depth (β = -1.45; 95% CI, -2.75 to -0.16; P = .03) of an ODP. The presence and structural characteristics of ODPs were associated with global and focal progression as assessed by the rate of OCT RNFL thinning. The assessment of ODP structure using swept-source OCT may help to predict the location of future progression.

Using spectral-domain optical coherence tomography to detect optic neuropathy in patients with craniosynostosis.

PubMed

Dagi, Linda R; Tiedemann, Laura M; Heidary, Gena; Robson, Caroline D; Hall, Amber M; Zurakowski, David

2014-12-01

Detecting and monitoring optic neuropathy in patients with craniosynostosis is a clinical challenge due to limited cooperation, and subjective measures of visual function. The purpose of this study was to appraise the correlation of peripapillary retinal nerve fiber layer (RNFL) thickness measured by spectral-domain ocular coherence tomography (SD-OCT) with indication of optic neuropathy based on fundus examination. The medical records of all patients with craniosynostosis presenting for ophthalmic evaluation during 2013 were retrospectively reviewed. The following data were abstracted from the record: diagnosis, historical evidence of elevated intracranial pressure, current ophthalmic evaluation and visual field results, and current peripapillary RNFL thickness. A total of 54 patients were included (mean age, 10.6 years [range, 2.4-33.8 years]). Thirteen (24%) had evidence of optic neuropathy based on current fundus examination. Of these, 10 (77%) demonstrated either peripapillary RNFL elevation and papilledema or depression with optic atrophy. Sensitivity for detecting optic atrophy was 88%; for papilledema, 60%; and for either form of optic neuropathy, 77%. Specificity was 94%, 90%, and 83%, respectively. Kappa agreement was substantial for optic atrophy (κ = 0.73) and moderate for papilledema (κ = 0.39) and for either form of optic neuropathy (κ = 0.54). Logistic regression indicated that peripapillary RNFL thickness was predictive of optic neuropathy (P < 0.001). Multivariable analysis demonstrated that RNFL thickness measurements were more sensitive at detecting optic neuropathy than visual field testing (likelihood ratio = 10.02; P = 0.002). Sensitivity and specificity of logMAR visual acuity in detecting optic neuropathy were 15% and 95%, respectively. Peripapillary RNFL thickness measured by SD-OCT provides adjunctive evidence for identifying optic neuropathy in patients with craniosynostosis and appears more sensitive at detecting optic atrophy than papilledema. Copyright © 2014 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Is the peripapillary retinal perfusion related to myopia in healthy eyes? A prospective comparative study.

PubMed

Wang, Xiaolei; Kong, Xiangmei; Jiang, Chunhui; Li, Mengwei; Yu, Jian; Sun, Xinghuai

2016-03-11

The aim of this study was to evaluate the peripapillary and parafoveal perfusion of young, healthy myopic subjects with spectral domain optical coherence tomography (OCT) angiography. A prospective comparative study was conducted from December 2014 to January 2015. Participants recruited from a population-based study performed by the Eye, Ear, Nose and Throat Hospital of Fudan University in Shanghai. A total of 78 Chinese normal subjects (78 eyes) with different refraction were included. Myopia was divided into 4 groups on the basis of the refractive status: 20 eyes with emmetropia (mean spherical equivalent (MSE) 0.50D to -0.50D), 20 eyes with mild myopia (MSE -0.75D to -2.75D), 20 eyes with moderate myopia (MSE -3.00D to -5.75D), and 18 eyes with high myopia (MSE≤-6.00D). Peripapillary and parafoveal retinal and choroidal perfusion parameters and their relationships with axial length (AL) and retinal nerve fibre layer (RNFL) thickness were analysed. Significant differences were found for the retinal flow index and vessel density in the peripapillary area among the 4 groups, but not in the parafoveal area. The high myopia group had the lowest peripapillary retinal flow index and vessel density. In addition, there was a negative correlation (β=-0.002, p=0.047) between the AL and peripapillary retinal flow index and a positive correlation between RNFL thickness and the peripapillary retinal perfusion parameters (flow index: β=0.001, p=0.006; vessel density: β=0.350, p=0.002) even after adjustment for other variables. Highly myopic eyes have a decreased peripapillary retinal perfusion compared with emmetropic eyes. Such vascular features might increase the susceptibility to vascular-related eye diseases. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Glaucoma Diagnostic Ability of the Optical Coherence Tomography Angiography Vessel Density Parameters.

PubMed

Chung, Jae Keun; Hwang, Young Hoon; Wi, Jae Min; Kim, Mijin; Jung, Jong Jin

2017-11-01

To investigate the glaucoma diagnostic abilities of vessel density parameters as determined by optical coherence tomography (OCT) angiography in different stages of glaucoma. A total of 113 healthy eyes and 140 glaucomatous eyes were enrolled. Diagnostic abilities of the OCT vessel density parameters in the optic nerve head (ONH), peripapillary, and macular regions were evaluated by calculating the area under the receiver operation characteristic curves (AUCs). AUCs of the peripapillary vessel density parameters and circumpapillary retinal nerve fiber layer (RNFL) thickness were compared. OCT angiography vessel densities in the ONH, peripapillary, and macular regions in the glaucomatous eyes were significantly lower than those in the healthy eyes (P < 0.05). Among the vessel density parameters, the average peripapillary vessel density showed higher AUC than the ONH and macular region (AUCs: 0.807, 0.566, and 0.651, respectively) for glaucoma detection. The peripapillary vessel density parameters showed similar AUCs with the corresponding sectoral RNFL thickness (P > 0.05). However, in the early stage of glaucoma, the AUCs of the inferotemporal and temporal peripapillary vessel densities were significantly lower than that of the RNFL thickness (P < 0.05). The glaucomatous eyes showed decreased vessel density as determined by OCT angiography. Although the peripapillary vessel density parameters showed similar glaucoma diagnostic ability with circumpapillary RNFL thickness, in the early stage, the vessel density parameters showed limited clinical value.

A hierarchical cluster analysis of normal-tension glaucoma using spectral-domain optical coherence tomography parameters.

PubMed

Bae, Hyoung Won; Ji, Yongwoo; Lee, Hye Sun; Lee, Naeun; Hong, Samin; Seong, Gong Je; Sung, Kyung Rim; Kim, Chan Yun

2015-01-01

Normal-tension glaucoma (NTG) is a heterogenous disease, and there is still controversy about subclassifications of this disorder. On the basis of spectral-domain optical coherence tomography (SD-OCT), we subdivided NTG with hierarchical cluster analysis using optic nerve head (ONH) parameters and retinal nerve fiber layer (RNFL) thicknesses. A total of 200 eyes of 200 NTG patients between March 2011 and June 2012 underwent SD-OCT scans to measure ONH parameters and RNFL thicknesses. We classified NTG into homogenous subgroups based on these variables using a hierarchical cluster analysis, and compared clusters to evaluate diverse NTG characteristics. Three clusters were found after hierarchical cluster analysis. Cluster 1 (62 eyes) had the thickest RNFL and widest rim area, and showed early glaucoma features. Cluster 2 (60 eyes) was characterized by the largest cup/disc ratio and cup volume, and showed advanced glaucomatous damage. Cluster 3 (78 eyes) had small disc areas in SD-OCT and were comprised of patients with significantly younger age, longer axial length, and greater myopia than the other 2 groups. A hierarchical cluster analysis of SD-OCT scans divided NTG patients into 3 groups based upon ONH parameters and RNFL thicknesses. It is anticipated that the small disc area group comprised of younger and more myopic patients may show unique features unlike the other 2 groups.

The Distinct Biometric Features of High Myopia Compared to Moderate Myopia.

PubMed

Chung, Hye Jin; Park, Chan Kee

2016-12-01

To evaluate changes in biometric parameters in myopic eyes. 412 eyes of 412 young myopic patients underwent ophthalmic examinations including assessments of refractive error, axial length (AL), anterior chamber depth (ACD), and central corneal thickness (CCT). By using spectral domain optical coherence tomography (SD-OCT), peripapillary retinal nerve fiber layer (pRNFL) thickness was measured. Subjects were divided into two groups: a moderate-myope group (-6 diopters (D) or more) and a high-myope group (less than -6 D). The relationships among ocular biometric parameters including pRNFL thickness, AL, ACD, and CCT were calculated for each group. In the moderate-myopia group, the anterior chamber deepened as AL increased (Pearson's coefficient = 0.346, p < 0.01). However, in the high-myopia group, ACD did not correlate with AL (Pearson's r = 0.065, p = 0.383). Average pRNFL thickness was also more related to SE than AL in highly myopic eyes. In highly myopic eyes, ACD did not increase as AL increased. pRNFL thickness was more related to SE than to AL. That might be due to the uneven elongation of anterior and posterior portions of the eyeball and the discrepancy between distance from the cornea to the fovea and distance from the cornea to the bottom of the eyeball as axial eye elongation. Interpretation of ocular biometric parameter in highly myopic eyes should consider these differences.

Morphological characteristics of the optic nerve evaluated by confocal laser tomography (HRT3) and laser polarimetry (GDx-VCC) in a normal population from the city of Barcelona.

PubMed

Fallon, M; Pazos, M; Morilla, A; Sebastián, M A; Xancó, R; Mora, C; Calderón, B; Vega, Z; Antón, A

2015-11-01

To evaluate morphological parameters of optic disc and retinal nerve fiber layer (RNFL) examined with confocal laser tomography (HRT3) and laser polarimetry (GDx-VCC) in a normal population, and analyze correlations of these parameters with demographic variables. Cross-sectional study in the context of a glaucoma screening campaign in the primary care center of Barcelona. The individuals selected were non-hypertensive Mediterranean Caucasians with risk for glaucoma development (individuals≥60 years old or≥40 years old with family history of glaucoma or intraocular pressure or myopia>3diopter). All subjects underwent a complete ophthalmic examination, confocal laser tomography (HRT3) and scanning laser polarimetry (GDX-VCC), subjects with results within normal limits only being included. Structural parameters were analyzed along with age, refraction, and pachymetry based on the Spearman rank correlation test. A total of 224 subjects included, with a mean age of 63.4±11.1 years. Disc areas, excavation and ring area were 2.14±0.52mm(2), 0.44±0.34mm (2) and 1.69±0.38mm(2), respectively. The mean RNFL (GDX) was 55.9±6.9μm. Age was correlated with lower ring volume, highest rate of cup shape measure, largest mean and maximum cup depth, lower nerve fiber index (NFI) and RNFL (all p-values below .05). The mean values and distribution of several parameters of the papilla and the RNFL in normal Mediterranean Caucasians population are presented. A loss of thickness of the RNFL, ring thinning, and enlarged cup was observed with increased age. Copyright © 2014 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Structure-Function Correlations using Scanning Laser Polarimetry in Primary Angle-Closure Glaucoma and Primary Open Angle Glaucoma

PubMed Central

Lee, Pei-Jung; Liu, Catherine Jui-Ling.; Wojciechowski, Robert; Bailey-Wilson, Joan E.; Cheng, Ching-Yu

2010-01-01

Purpose To assess the correlations between retinal nerve fiber layer (RNFL) thickness measured with scanning laser polarimetry (SLP) and visual field (VF) sensitivity in primary open angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). Design Prospective, comparative, observational cases series Methods Fifty patients with POAG and 56 with PACG were examined using SLP with variable corneal compensation (GDx VCC) and Humphrey VF analyzer between August 2005 and July 2006 at Taipei Veterans General Hospital. Correlations between RNFL thickness and VF sensitivity, expressed as mean sensitivity (MS) in both decibel (dB) and 1/Lambert (L) scales, were estimated by Spearman's rank correlation coefficient (rs) and multivariate median regression models (pseudo R2). The correlations were determined globally and for six RNFL sectors and their corresponding VF regions. Results The correlation between RNFL thickness and MS (in dB) was weaker in the PACG group (rs = 0.38, P = 0.004, pseudo R2 = 0.17) than in the POAG group (rs = 0.51, P <0.001, pseudo R2 = 0.31), but the difference in the magnitude of correlation was not significant (P = 0.42).With Bonferroni correction, the structure-function correlation was significant in the superotemporal (rs = 0.62), superonasal (rs = 0.56), inferonasal (rs = 0.53), and inferotemporal (rs = 0.50) sectors in the POAG group (all P <0.001), while it was significant only in the superotemporal (rs = 0.53) and inferotemporal (rs = 0.48) sectors in the PACG group (both P <0.001). The results were similar when MS was expressed as 1/L scale. Conclusions Both POAG and PACG eyes had moderate structure-function correlations using SLP. Compared to eyes with POAG, fewer RNFL sectors have significant structure-function correlations in eyes with PACG. PMID:20202618

Diagnostic capability of spectral-domain optical coherence tomography for glaucoma.

PubMed

Wu, Huijuan; de Boer, Johannes F; Chen, Teresa C

2012-05-01

To determine the diagnostic capability of spectral-domain optical coherence tomography in glaucoma patients with visual field defects. Prospective, cross-sectional study. Participants were recruited from a university hospital clinic. One eye of 85 normal subjects and 61 glaucoma patients with average visual field mean deviation of -9.61 ± 8.76 dB was selected randomly for the study. A subgroup of the glaucoma patients with early visual field defects was calculated separately. Spectralis optical coherence tomography (Heidelberg Engineering, Inc) circular scans were performed to obtain peripapillary retinal nerve fiber layer (RNFL) thicknesses. The RNFL diagnostic parameters based on the normative database were used alone or in combination for identifying glaucomatous RNFL thinning. To evaluate diagnostic performance, calculations included areas under the receiver operating characteristic curve, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio. Overall RNFL thickness had the highest area under the receiver operating characteristic curve values: 0.952 for all patients and 0.895 for the early glaucoma subgroup. For all patients, the highest sensitivity (98.4%; 95% confidence interval, 96.3% to 100%) was achieved by using 2 criteria: ≥ 1 RNFL sectors being abnormal at the < 5% level and overall classification of borderline or outside normal limits, with specificities of 88.9% (95% confidence interval, 84.0% to 94.0%) and 87.1% (95% confidence interval, 81.6% to 92.5%), respectively, for these 2 criteria. Statistical parameters for evaluating the diagnostic performance of the Spectralis spectral-domain optical coherence tomography were good for early perimetric glaucoma and were excellent for moderately advanced perimetric glaucoma. Copyright © 2012 Elsevier Inc. All rights reserved.

Combining information from 3 anatomic regions in the diagnosis of glaucoma with time-domain optical coherence tomography.

PubMed

Wang, Mingwu; Lu, Ake Tzu-Hui; Varma, Rohit; Schuman, Joel S; Greenfield, David S; Huang, David

2014-03-01

To improve the diagnosis of glaucoma by combining time-domain optical coherence tomography (TD-OCT) measurements of the optic disc, circumpapillary retinal nerve fiber layer (RNFL), and macular retinal thickness. Ninety-six age-matched normal and 96 perimetric glaucoma participants were included in this observational, cross-sectional study. Or-logic, support vector machine, relevance vector machine, and linear discrimination function were used to analyze the performances of combined TD-OCT diagnostic variables. The area under the receiver-operating curve (AROC) was used to evaluate the diagnostic accuracy and to compare the diagnostic performance of single and combined anatomic variables. The best RNFL thickness variables were the inferior (AROC=0.900), overall (AROC=0.892), and superior quadrants (AROC=0.850). The best optic disc variables were horizontal integrated rim width (AROC=0.909), vertical integrated rim area (AROC=0.908), and cup/disc vertical ratio (AROC=0.890). All macular retinal thickness variables had AROCs of 0.829 or less. Combining the top 3 RNFL and optic disc variables in optimizing glaucoma diagnosis, support vector machine had the highest AROC, 0.954, followed by or-logic (AROC=0.946), linear discrimination function (AROC=0.946), and relevance vector machine (AROC=0.943). All combination diagnostic variables had significantly larger AROCs than any single diagnostic variable. There are no significant differences among the combination diagnostic indices. With TD-OCT, RNFL and optic disc variables had better diagnostic accuracy than macular retinal variables. Combining top RNFL and optic disc variables significantly improved diagnostic performance. Clinically, or-logic classification was the most practical analytical tool with sufficient accuracy to diagnose early glaucoma.

Perimetric measurements with flicker-defined form stimulation in comparison with conventional perimetry and retinal nerve fiber measurements.

PubMed

Horn, Folkert K; Tornow, Ralf P; Jünemann, Anselm G; Laemmer, Robert; Kremers, Jan

2014-04-11

We compared the results of flicker-defined form (FDF) perimetry with standard automated perimetry (SAP) and retinal nerve fiber layer (RNFL) thickness measurements using spectral domain optical coherence tomography (OCT). A total of 64 healthy subjects, 45 ocular hypertensive patients, and 97 "early" open-angle glaucoma (OAG) patients participated in this study. Definition of glaucoma was based exclusively on glaucomatous optic disc appearance. All subjects underwent FDF perimetry, SAP, and peripapillary measurements of the RNFL thickness. The FDF perimetry and SAP were performed at identical test locations (G1 protocol). Exclusion criteria were subjects younger than 34 years, SAP mean defect (SAP MD) > 5 dB, eye diseases other than glaucoma, or nonreliable FDF measurements. The correlations between the perimetric data on one hand and RNFL thicknesses on the other hand were analyzed statistically. The age-corrected sensitivity values and the local results from the controls were used to determine FDF mean defect (FDF MD). The FDF perimetry and SAP showed high concordance in this cohort of experienced patients (MD values, R = -0.69, P < 0.001). Of a total of 42 OAG patients with abnormal SAP MD, 38 also displayed abnormal FDF MD. However, FDF MD was abnormal in 28 of 55 OAG patients with normal SAP MD. The FDF MD was significantly (R = -0.61, P < 0.001) correlated with RNFL thickness with a (nonsignificantly) larger correlation coefficient than conventional SAP MD (R = -0.48, P < 0.001). The FDF perimetry is able to uncover functional changes concurrent with the changes in RNFL thickness. The FDF perimetry may be an efficient functional test to detect early glaucomatous nerve atrophy. (ClinicalTrials.gov number, NCT00494923.).

Long-term structural retinal changes in patients with optic neuritis related to multiple sclerosis.

PubMed

Andersen, Maria Rene; Roar, Malte; Sejbaek, Tobias; Illes, Zsolt; Grauslund, Jakob

2017-01-01

To evaluate the long-term structural and functional outcome in patients with multiple sclerosis (MS) with and without a history of optic neuritis (ON). This was a cross-sectional study of 82 patients diagnosed with MS between 2000 and 2006 from a tertiary hospital center in Denmark. Patients gave a self-reported history of ON, and functional (visual acuity and color vision) and structural (spectra domain optical coherence tomography) markers of vision were tested. Median age and MS duration at the time of the clinical examination were 49.9 years (range 30.7-72.6 years) and 13 years (range 9-15 years), respectively. ON was not associated with impairment of visual acuity or color vision. Twenty-three patients had a history of ON in at least one eye. Compared to non-affected patients, these had a lower inferior (109 vs 113 μm, P =0.04) and temporal retinal nerve fiber layer (RNFL) thickness (56 vs 67 μm, P =0.01). In an age- and sex-adjusted logistic regression model, lower inferior and temporal RNFL were associated with a higher risk of ON (odds ratio [OR] 1.56 [95% confidence interval {CI} 1.01-2.41] and OR 1.74 [95% CI 1.10-2.77] per 10 μm decrement in RNFL thickness, respectively). Twenty patients had a history of ON in one eye. Compared to the non-affected eye, this eye had a lower RNFL (109 vs 115 μm, P =0.04) and a higher central retinal thickness/mean RNFL ratio (2.7 vs 2.4, P =0.04). Although patients with long-term MS and a previous history of ON did not have any functional loss of vision, structural neurodegeneration could be demonstrated in the affected eye.

Comparison of Pattern Electroretinography and Optical Coherence Tomography Parameters in Patients with Primary Open-Angle Glaucoma and Ocular Hypertension

PubMed Central

Tiryaki Demir, Semra; Oba, Mehmet Ersin; Erdoğan, Ezgi Tuna; Odabaşı, Mahmut; Dirim, Ayşe Burcu; Demir, Mehmet; Can, Efe; Kara, Orhan; Yekta Şendül, Selam

2015-01-01

Objectives: To investigate the correlation of visual field (VF), pattern electroretinography (PERG) and Fourier domain optical coherence tomography (FD-OCT) results in patients with ocular hypertension (OHT) and early primary open-angle glaucoma (POAG). Materials and Methods: The study included 72 eyes of 37 patients with early POAG, 76 eyes of 38 patients with OHT, and 60 eyes of 30 controls. All subjects underwent full ophthalmologic examination, VF assessment with 24-2 Humphrey standard automated perimetry (Swedish Interactive Thresholding Algorithm (SITA)-Standard), retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness measurement with FD-OCT, and PERG P50 and N95 wave latency and amplitude measurements with electroretinography (Nihon Kohden). Results: With the exception of the nasal quadrant, all GCC parameters and RNFL results were significantly lower in the POAG group compared to the OHT and control groups. There was no statistically significant difference between the OHT and control group. PERG amplitudes were lower in the POAG and OHT groups than in the control group. Reduction in N95 amplitude was greater than that of P50 amplitude. No difference was detected in PERG latencies among groups. GCC was significantly correlated with VF and RNFL in the POAG group. Conclusion: Significant thinning of the GCC and RNFL occurs in addition to VF pathologies in patients with early POAG, and these examinations should be concomitantly evaluated. During diagnostic assessment of patients with early POAG, GCC and RNFL analysis by FD-OCT are highly effective. GCC is as reliable as RNLF in the early diagnosis of glaucoma and there is a highly significant correlation between them. Dysfunction of ganglion cells in patients with OHT may be detected earlier using PERG amplitude analysis. PMID:27800239

Neuroretinal alterations in the early stages of diabetic retinopathy in patients with type 2 diabetes mellitus.

PubMed

Carpineto, P; Toto, L; Aloia, R; Ciciarelli, V; Borrelli, E; Vitacolonna, E; Di Nicola, M; Di Antonio, L; Mastropasqua, R

2016-05-01

PurposeTo study neuroretinal alterations in patients affected by type 2 diabetes with no diabetic retinopathy (DR) or mild nonproliferative diabetic retinopathy (NPDR) and without any sign of diabetic macular edema.Patients and methodsIn total, 150 type 2 diabetic patients with no (131 eyes) or mild NPDR (19 eyes) and 50 healthy controls were enrolled in our study. All underwent a complete ophthalmologic examination, including Spectral-Domain optical coherence tomography (SD-OCT). Ganglion cell-inner plexiform layer (GC-IPL) and retinal nerve fiber layer (RNFL) thickness values were calculated after automated segmentation of SD-OCT scans.ResultsMean best-corrected visual acuity was 0.0±0.0 LogMAR in all the groups. Mean GC-IPL thickness was 80.6±8.1 μm in diabetic patients and 85.3±9.9 μm in healthy controls, respectively (P=0.001). Moreover, evaluating the two different diabetic groups, GC-IPL thickness was 80.7±8.1 μm and 79.7±8.8 μm in no-DR and mild-NPDR group (P=0.001 and P=0.022 compared with healthy controls, respectively). Average RNFL thickness was 86.1±10.1 μm in diabetes patients and 91.2±7.3 μm in controls, respectively (P=0.003). RNFL thickness was 86.4±10.2 μm in no-DR group and 84.1±9.4 μm in mild-NPDR group (P=0.007 and P=0.017 compared with healthy controls, respectively).ConclusionWe demonstrated a significantly reduced GC-IPL and RNFL thickness values in both no-DR and mild-NPDR groups compared with healthy controls. These data confirmed neuroretinal alterations are early in diabetes, preceding microvascular damages.

The Impact of Retardance Pattern Variability on Nerve Fiber Layer Measurements over Time Using GDx with Variable and Enhanced Corneal Compensation

PubMed Central

Grewal, Dilraj S.; Sehi, Mitra; Cook, Richard J.

2011-01-01

Purpose. To examine the impact of retardance pattern variability on retinal nerve fiber layer (RNFL) measurements over time using scanning laser polarimetry with variable (GDxVCC) and enhanced corneal compensation (GDxECC; both by Carl Zeiss Meditec, Inc., Dublin, CA). Methods. Glaucoma suspect and glaucomatous eyes with 4 years of follow-up participating in the Advanced Imaging in Glaucoma Study were prospectively enrolled. All eyes underwent standard automated perimetry (SAP), GDxVCC, and GDxECC imaging every 6 months. SAP progression was determined with point-wise linear regression analysis of SAP sensitivity values. Typical scan score (TSS) values were extracted as a measure of retardance image quality; an atypical retardation pattern (ARP) was defined as TSS < 80. TSS fluctuation over time was measured using three parameters: change in TSS from baseline, absolute difference (maximum minus minimum TSS value), and TSS variance. Linear mixed-effects models that accommodated the association between the two eyes were constructed to evaluate the relationship between change in TSS and RNFL thickness over time. Results. Eighty-six eyes (51 suspected glaucoma, 35 glaucomatous) of 45 patients were enrolled. Twenty (23.3%) eyes demonstrated SAP progression. There was significantly greater fluctuation in TSS over time with GDxVCC compared with GDxECC as measured by absolute difference (18.40 ± 15.35 units vs. 2.50 ± 4.69 units; P < 0.001), TSS variance (59.63 ± 87.27 units vs. 3.82 ± 9.63 units, P < 0.001), and change in TSS from baseline (−0.83 ± 11.2 vs. 0.25 ± 2.9, P = 0.01). The change in TSS over time significantly (P = 0.006) influenced the TSNIT average RNFL thickness when measured by GDxVCC but not by GDxECC. Conclusions. Longitudinal images obtained with GDxECC have significantly less variability in TSS and retardance patterns and have reduced bias produced by ARP on RNFL progression assessment. PMID:21296821

Compromised Integrity of Central Visual Pathways in Patients With Macular Degeneration.

PubMed

Malania, Maka; Konrad, Julia; Jägle, Herbert; Werner, John S; Greenlee, Mark W

2017-06-01

Macular degeneration (MD) affects the central retina and leads to gradual loss of foveal vision. Although, photoreceptors are primarily affected in MD, the retinal nerve fiber layer (RNFL) and central visual pathways may also be altered subsequent to photoreceptor degeneration. Here we investigate whether retinal damage caused by MD alters microstructural properties of visual pathways using diffusion-weighted magnetic resonance imaging. Six MD patients and six healthy control subjects participated in the study. Retinal images were obtained by spectral-domain optical coherence tomography (SD-OCT). Diffusion tensor images (DTI) and high-resolution T1-weighted structural images were collected for each subject. We used diffusion-based tensor modeling and probabilistic fiber tractography to identify the optic tract (OT) and optic radiations (OR), as well as nonvisual pathways (corticospinal tract and anterior fibers of corpus callosum). Fractional anisotropy (FA) and axial and radial diffusivity values (AD, RD) were calculated along the nonvisual and visual pathways. Measurement of RNFL thickness reveals that the temporal circumpapillary retinal nerve fiber layer was significantly thinner in eyes with macular degeneration than normal. While we did not find significant differences in diffusion properties in nonvisual pathways, patients showed significant changes in diffusion scalars (FA, RD, and AD) both in OT and OR. The results indicate that the RNFL and the white matter of the visual pathways are significantly altered in MD patients. Damage to the photoreceptors in MD leads to atrophy of the ganglion cell axons and to corresponding changes in microstructural properties of central visual pathways.

Comparative study of the retinal nerve fibre layer thickness performed with optical coherence tomography and GDx scanning laser polarimetry in patients with primary open-angle glaucoma.

PubMed

Wasyluk, Jaromir T; Jankowska-Lech, Irmina; Terelak-Borys, Barbara; Grabska-Liberek, Iwona

2012-03-01

We compared the parameters of retinal nerve fibre layer in patients with advanced glaucoma with the use of different OCT (Optical Coherence Tomograph) devices in relation to analogical measurements performed with GDx VCC (Nerve Fiber Analyzer with Variable Corneal Compensation) scanning laser polarimetry. Study subjects had advanced primary open-angle glaucoma, previously treated conservatively, diagnosed and confirmed by additional examinations (visual field, ophthalmoscopy of optic nerve, gonioscopy), A total of 10 patients were enrolled (9 women and 1 man), aged 18-70 years of age. Nineteen eyes with advanced glaucomatous neuropathy were examined. 1) Performing a threshold perimetry Octopus, G2 strategy and ophthalmoscopy of optic nerve to confirm the presence of advanced primary open-angle glaucoma; 2) performing a GDx VCC scanning laser polarimetry of retinal nerve fibre layer; 3) measuring the retinal nerve fibre layer thickness with 3 different optical coherence tomographs. The parameters of the retinal nerve fibre layer thickness are highly correlated between the GDx and OCT Stratus and 3D OCT-1000 devices in mean retinal nerve fibre layer thickness, retinal nerve fibre layer thickness in the upper sector, and correlation of NFI (GDx) with mean retinal nerve fibre layer thickness in OCT examinations. Absolute values of the retinal nerve fibre layer thickness (measured in µm) differ significantly between GDx and all OCT devices. Examination with OCT devices is a sensitive diagnostic method of glaucoma, with good correlation with the results of GDx scanning laser polarimetry of the patients.

Optical Coherence Tomography in Alzheimer's Disease: A Meta-Analysis.

PubMed

Coppola, Gianluca; Di Renzo, Antonio; Ziccardi, Lucia; Martelli, Francesco; Fadda, Antonello; Manni, Gianluca; Barboni, Piero; Pierelli, Francesco; Sadun, Alfredo A; Parisi, Vincenzo

2015-01-01

Alzheimer's disease (AD) is a neurodegenerative disorder, which is likely to start as mild cognitive impairment (MCI) several years before the its full-blown clinical manifestation. Optical coherence tomography (OCT) has been used to detect a loss in peripapillary retina nerve fiber layer (RNFL) and a reduction in macular thickness and volume of people affected by MCI or AD. Here, we performed an aggregate meta-analysis combining results from different studies. Data sources were case-control studies published between January 2001 and August 2014 (identified through PubMed and Google Scholar databases) that examined the RNFL thickness by means of OCT in AD and MCI patients compared with cognitively healthy controls. 11 studies were identified, including 380 patients with AD, 68 with MCI and 293 healthy controls (HC). The studies suggest that the mean RNFL thickness is reduced in MCI (weighted mean differences in μm, WMD = -13.39, 95% CI: -17.34 to -9.45, p = 0.031) and, even more so, in AD (WMD = -15.95, 95% CI: -21.65 to -10.21, p<0.0001) patients compared to HC. RNFL in the 4 quadrants were all significantly thinner in AD superior (superior WMD = -24.0, 95% CI: -34.9 to -13.1, p<0.0001; inferior WMD = -20.8, 95% CI: -32.0 to -9.7, p<0.0001; nasal WMD = -14.7, 95% CI: -23.9 to -5.5, p<0.0001; and temporal WMD = -10.7, 95% CI: -19.9 to -1.4, p<0.0001); the same significant reduction in quadrant RNFL was observed in MCI patients compared with HC (Inferior WMD = -20.22, 95% CI: -30.41 to -10.03, p = 0.0001; nasal WMD = -7.4, 95% CI: -10.08 to -4.7, p = 0.0000; and temporal WMD = -6.88, 95% CI: -12.62 to -1.13, p = 0.01), with the exception of superior quadrant (WMD = -19.45, 95% CI: -40.23 to 1.32, p = 0.06). Results from the meta-analysis support the important role of OCT for RNFL analysis in monitoring the progression of AD and in assessing the effectiveness of purported AD treatments.

Relationship between Scanning Laser Polarimetry with Enhanced Corneal Compensation and with Variable Corneal Compensation

PubMed Central

Kim, Kyung Hoon; Choi, Jaewan; Lee, Chang Hwan; Cho, Beom-Jin; Kook, Michael S.

2008-01-01

Purpose To evaluate the structure-function relationships between retinal sensitivity measured by Humphrey visual field analyzer (HVFA) and the retinal nerve fiber layer (RNFL) thickness measured by scanning laser polarimetry (SLP) with variable corneal compensation (VCC) and enhanced corneal compensation (ECC) in glaucomatous and healthy eyes. Methods Fifty-three eyes with an atypical birefringence pattern (ABP) based on SLP-VCC (28 glaucomatous eyes and 25 normal healthy eyes) were enrolled in this cross-sectional study. RNFL thickness was measured by both VCC and ECC techniques, and the visual field was examined by HVFA with 24-2 full-threshold program. The relationships between RNFL measurements in superior and inferior sectors and corresponding retinal mean sensitivity were sought globally and regionally with linear regression analysis in each group. Coefficients of the determination were calculated and compared between VCC and ECC techniques. Results In eyes with ABP, R2 values for the association between SLP parameters and retinal sensitivity were 0.06-0.16 with VCC, whereas they were 0.21-0.48 with ECC. The association of RNFL thickness with retinal sensitivity was significantly better with ECC than with VCC in 5 out of 8 regression models between SLP parameters and HVF parameters (P<0.05). Conclusions The strength of the structure-function association was higher with ECC than with VCC in eyes with ABP, which suggests that the ECC algorithm is a better approach for evaluating the structure-function relationship in eyes with ABP. PMID:18323701

Axonal loss from acute optic neuropathy documented by scanning laser polarimetry

PubMed Central

Meier, F M; Bernasconi, P; Stürmer, J; Caubergh, M-J; Landau, K

2002-01-01

Background/aims: Retinal nerve fibre layer analysis by scanning laser polarimetry has been shown to facilitate diagnosis of glaucoma while its role in glaucoma follow up is still unclear. A major difficulty is the slow reduction of retinal nerve fibre layer thickness in glaucomatous optic neuropathy. Eyes of patients were studied after acute retrobulbar optic nerve lesion in order to evaluate the usefulness of scanning laser polarimetry in documenting retinal nerve fibre layer loss over time. Methods: Five patients who suffered severe retrobulbar optic neuropathy have had repeated measurements of the retinal nerve fibre layer using scanning laser polarimetry at various intervals, the first examination being within 1 week of injury. Results: All eyes showed a marked decrease in peripapillary retinal nerve fibre layer thickness, which followed an exponential curve and occurred predominantly within 8 weeks of injury. Compared to a previous study using red-free photographs, scanning laser polarimetry showed retinal nerve fibre layer loss earlier in the course of descending atrophy. Conclusion: Scanning laser polarimetry is useful for early detection and documentation of retinal nerve fibre layer loss following acute injury to the retrobulbar optic nerve. It seems to be a promising tool for follow up of individual glaucoma patients. PMID:11864884

High-Resolution Imaging of the Optic Nerve and Retina in Optic Nerve Hypoplasia

PubMed Central

Pilat, Anastasia; Sibley, Daniel; McLean, Rebecca J.; Proudlock, Frank A.; Gottlob, Irene

2015-01-01

Purpose To investigate the optic nerve and macular morphology in patients with optic nerve hypoplasia (ONH) using spectral-domain optical coherence tomography (SD OCT). Design Prospective, cross-sectional, observational study. Subjects A total of 16 participants with ONH (10 female and 6 male; mean age, 17.2 years; 6 bilateral involvement) and 32 gender-, age-, ethnicity-, and refraction-matched healthy controls. Methods High-resolution SD OCT (Copernicus [Optopol Technology S.A., Zawiercie, Poland], 3 μm resolution) and handheld SD OCT (Bioptigen Inc [Research Triangle Park, NC], 2.6 μm resolution) devices were used to acquire horizontal scans through the center of the optic disc and macula. Main Outcome Measures Horizontal optic disc/cup and rim diameters, cup depth, peripapillary retinal nerve fiber layer (RNFL), and thickness of individual retinal layers in participants with ONH and in controls. Results Patients with ONH had significantly smaller discs (P < 0.03 and P < 0.001 compared with unaffected eye and healthy controls, respectively), horizontal cup diameter (P < 0.02 for both), and cup depth (P < 0.02 and P < 0.01, respectively). In the macula, significantly thinner RNFL (nasally), ganglion cell layer (GCL) (nasally and temporally), inner plexiform layer (IPL) (nasally), outer nuclear layer (ONL) (nasally), and inner segment (centrally and temporally) were found in patients with ONH compared with the control group (P < 0.05 for all comparisons). Continuation of significantly thicker GCL, IPL, and outer plexiform layer in the central retinal area (i.e., foveal hypoplasia) was found in more than 80% of patients with ONH. Clinically unaffected fellow eyes of patients with ONH showed mild features of underdevelopment. Visual acuity and presence of septo-optic dysplasia were associated with changes in GCL and IPL. Sensitivity and specificity for the detection of ONH based on disc and retinal optical coherence tomography (OCT) parameters were >80%. Conclusions Our study provides evidence of retinal changes in ONH. In addition to thinning of retina layers mainly involving the RNFL and GCL, signs reminiscent of foveal hypoplasia were observed in patients with ONH. Optic nerve and foveal parameters measured using OCT showed high sensitivity and specificity for detecting ONH, demonstrating their useful for clinical diagnosis. PMID:25939636

Diagnostic classification of macular ganglion cell and retinal nerve fiber layer analysis: differentiation of false-positives from glaucoma.

PubMed

Kim, Ko Eun; Jeoung, Jin Wook; Park, Ki Ho; Kim, Dong Myung; Kim, Seok Hwan

2015-03-01

To investigate the rate and associated factors of false-positive diagnostic classification of ganglion cell analysis (GCA) and retinal nerve fiber layer (RNFL) maps, and characteristic false-positive patterns on optical coherence tomography (OCT) deviation maps. Prospective, cross-sectional study. A total of 104 healthy eyes of 104 normal participants. All participants underwent peripapillary and macular spectral-domain (Cirrus-HD, Carl Zeiss Meditec Inc, Dublin, CA) OCT scans. False-positive diagnostic classification was defined as yellow or red color-coded areas for GCA and RNFL maps. Univariate and multivariate logistic regression analyses were used to determine associated factors. Eyes with abnormal OCT deviation maps were categorized on the basis of the shape and location of abnormal color-coded area. Differences in clinical characteristics among the subgroups were compared. (1) The rate and associated factors of false-positive OCT maps; (2) patterns of false-positive, color-coded areas on the GCA deviation map and associated clinical characteristics. Of the 104 healthy eyes, 42 (40.4%) and 32 (30.8%) showed abnormal diagnostic classifications on any of the GCA and RNFL maps, respectively. Multivariate analysis revealed that false-positive GCA diagnostic classification was associated with longer axial length and larger fovea-disc angle, whereas longer axial length and smaller disc area were associated with abnormal RNFL maps. Eyes with abnormal GCA deviation map were categorized as group A (donut-shaped round area around the inner annulus), group B (island-like isolated area), and group C (diffuse, circular area with an irregular inner margin in either). The axial length showed a significant increasing trend from group A to C (P=0.001), and likewise, the refractive error was more myopic in group C than in groups A (P=0.015) and B (P=0.014). Group C had thinner average ganglion cell-inner plexiform layer thickness compared with other groups (group A=B>C, P=0.004). Abnormal OCT diagnostic classification should be interpreted with caution, especially in eyes with long axial lengths, large fovea-disc angles, and small optic discs. Our findings suggest that the characteristic patterns of OCT deviation map can provide useful clues to distinguish glaucomatous changes from false-positive findings. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Comparative study of the retinal nerve fibre layer thickness performed with optical coherence tomography and GDx scanning laser polarimetry in patients with primary open-angle glaucoma

PubMed Central

Wasyluk, Jaromir T.; Jankowska-Lech, Irmina; Terelak-Borys, Barbara; Grabska-Liberek, Iwona

2012-01-01

Summary Background We compared the parameters of retinal nerve fibre layer in patients with advanced glaucoma with the use of different OCT (Optical Coherence Tomograph) devices in relation to analogical measurements performed with GDx VCC (Nerve Fiber Analyzer with Variable Corneal Compensation) scanning laser polarimetry. Material/Methods Study subjects had advanced primary open-angle glaucoma, previously treated conservatively, diagnosed and confirmed by additional examinations (visual field, ophthalmoscopy of optic nerve, gonioscopy), A total of 10 patients were enrolled (9 women and 1 man), aged 18–70 years of age. Nineteen eyes with advanced glaucomatous neuropathy were examined. 1) Performing a threshold perimetry Octopus, G2 strategy and ophthalmoscopy of optic nerve to confirm the presence of advanced primary open-angle glaucoma; 2) performing a GDx VCC scanning laser polarimetry of retinal nerve fibre layer; 3) measuring the retinal nerve fibre layer thickness with 3 different optical coherence tomographs. Results The parameters of the retinal nerve fibre layer thickness are highly correlated between the GDx and OCT Stratus and 3D OCT-1000 devices in mean retinal nerve fibre layer thickness, retinal nerve fibre layer thickness in the upper sector, and correlation of NFI (GDx) with mean retinal nerve fibre layer thickness in OCT examinations. Absolute values of the retinal nerve fibre layer thickness (measured in μm) differ significantly between GDx and all OCT devices. Conclusions Examination with OCT devices is a sensitive diagnostic method of glaucoma, with good correlation with the results of GDx scanning laser polarimetry of the patients. PMID:22367131

Automatic reconstruction of the muscle architecture from the superficial layer fibres data.

PubMed

Kohout, Josef; Cholt, David

2017-10-01

Physiological cross-sectional area (PCSA) of a muscle plays a significant role in determining the force contribution of muscle fascicles to skeletal movement. This parameter is typically calculated from the lengths of muscle fibres selectively sampled from the superficial layer of the muscle. However, recent studies have found that the length of fibres in the superficial layer often differs significantly (p < 0.5) from the length of fibres in the deep layer. As a result, PCSA estimation is inaccurate. In this paper, we propose a method to automatically reconstruct fibres in the whole volume of a muscle from those selectively sampled on the superficial layer. The method performs a centripetal Catmull-Rom interpolation of the input fibres within the volume of a muscle represented by its 3D surface model, automatically distributing the fibres among multiple heads of the muscle and shortening the deep fibres to support large attachment areas with extremely acute angles. Our C++ implementation runs in a couple of seconds on commodity hardware providing realistic results for both artificial and real data sets we tested. The fibres produced by the method can be used directly to determine the personalised mechanical muscle functioning. Our implementation is publicly available for the researchers at https://mi.kiv.zcu.cz/. Copyright © 2017 Elsevier B.V. All rights reserved.

Test study on the performance of shielding configuration with stuffed layer under hypervelocity impact

NASA Astrophysics Data System (ADS)

Ke, Fa-wei; Huang, Jie; Wen, Xue-zhong; Ma, Zhao-xia; Liu, Sen

2016-10-01

In order to study the cracking and intercepting mechanism of stuffed layer configuration on the debris cloud and to develop stuffed layer configuration with better performance, the hypervelocity impact tests on shielding configurations with stuffed layer were carried out. Firstly, the hypervelocity impact tests on the shielding configuration with stuffed layer of 3 layer ceramic fibre and 3 layer aramid fibre were finished, the study results showed that the debris cloud generated by the aluminum sphere impacting bumper at the velocity of about 6.2 km/s would be racked and intercepted by the stuffed layer configuration efficiently when the ceramic fibre layers and aramid fibre layers were jointed together, however, the shielding performance would be declined when the ceramic fibre layers and aramid fibre layers were divided by some distance. The mechanism of stuffed layer racking and intercepting the debris cloud was analyzed according to the above test results. Secondly, based on the mechanism of the stuffed layer cracking and intercepint debirs cloud the hypervelocity impact tests on the following three stuffed layer structures with the equivalent areal density to the 1 mm-thick aluminum plate were also carried out to compare their performance of cracking and intercepting debris cloud. The mechanisms of stuffed layer racking and intercepting the debris cloud were validated by the test result. Thirdly, the influence of the stuffed layer position on the shielding performance was studied by the test, too. The test results would provide reference for the design of better performance shielding configuration with stuffed layer.

Green disease in optical coherence tomography diagnosis of glaucoma.

PubMed

Sayed, Mohamed S; Margolis, Michael; Lee, Richard K

2017-03-01

Optical coherence tomography (OCT) has become an integral component of modern glaucoma practice. Utilizing color codes, OCT analysis has rendered glaucoma diagnosis and follow-up simpler and faster for the busy clinician. However, green labeling of OCT parameters suggesting normal values may confer a false sense of security, potentially leading to missed diagnoses of glaucoma and/or glaucoma progression. Conditions in which OCT color coding may be falsely negative (i.e., green disease) are identified. Early glaucoma in which retinal nerve fiber layer (RNFL) thickness and optic disc parameters, albeit labeled green, are asymmetric in both eyes may result in glaucoma being undetected. Progressively decreasing RNFL thickness may reveal the presence of progressive glaucoma that, because of green labeling, can be missed by the clinician. Other ocular conditions that can increase RNFL thickness can make the diagnosis of coexisting glaucoma difficult. Recently introduced progression analysis features of OCT may help detect green disease. Recognition of green disease is of paramount importance in diagnosing and treating glaucoma. Understanding the limitations of imaging technologies coupled with evaluation of serial OCT analyses, prompt clinical examination, and structure-function correlation is important to avoid missing real glaucoma requiring treatment.

Correlation between Visual Field Index and Other Functional and Structural Measures in Glaucoma Patients and Suspects.

PubMed

Iutaka, Natalia A; Grochowski, Rubens A; Kasahara, Niro

2017-01-01

To evaluate the correlation between visual field index (VFI) and both structural and functional measures of the optic disc in primary open angle glaucoma patients and suspects. In this retrospective study, 162 glaucoma patients and suspects underwent standard automated perimetry (SAP), retinography, and retinal nerve fiber layer (RNFL) measurement. The optic disc was stratified according to the vertical cup/disc ratio (C/D) and sorted by the disc damage likelihood scale (DDLS). RNFL was measured with the optical coherence tomography. The VFI perimetry was correlated with the mean deviation (MD) and pattern standard deviation (PSD) obtained by SAP, and structural parameters by Pearson's correlation coefficients. VFI displayed strong correlation with MD ( R = 0.959) and PSD ( R = -0.744). The linear correlations between VFI and structural measures including C/D ( R = -0.179, P = 0.012), DDLS ( R = -0.214, P = 0.006), and RNFL ( R = 0.416, P < 0.001) were weak but statistically significant. VFI showed a strong correlation with MD and PSD but demonstrated a weak correlation with structural measures. It can possibly be used as a marker for functional impairment severity in patients with glaucoma.

Optical Coherence Tomography Angiography Vessel Density in Healthy, Glaucoma Suspect, and Glaucoma Eyes

PubMed Central

Yarmohammadi, Adeleh; Zangwill, Linda M.; Diniz-Filho, Alberto; Suh, Min Hee; Manalastas, Patricia Isabel; Fatehee, Naeem; Yousefi, Siamak; Belghith, Akram; Saunders, Luke J.; Medeiros, Felipe A.; Huang, David; Weinreb, Robert N.

2016-01-01

Purpose The purpose of this study was to compare retinal nerve fiber layer (RNFL) thickness and optical coherence tomography angiography (OCT-A) retinal vasculature measurements in healthy, glaucoma suspect, and glaucoma patients. Methods Two hundred sixty-one eyes of 164 healthy, glaucoma suspect, and open-angle glaucoma (OAG) participants from the Diagnostic Innovations in Glaucoma Study with good quality OCT-A images were included. Retinal vasculature information was summarized as a vessel density map and as vessel density (%), which is the proportion of flowing vessel area over the total area evaluated. Two vessel density measurements extracted from the RNFL were analyzed: (1) circumpapillary vessel density (cpVD) measured in a 750-μm-wide elliptical annulus around the disc and (2) whole image vessel density (wiVD) measured over the entire image. Areas under the receiver operating characteristic curves (AUROC) were used to evaluate diagnostic accuracy. Results Age-adjusted mean vessel density was significantly lower in OAG eyes compared with glaucoma suspects and healthy eyes. (cpVD: 55.1 ± 7%, 60.3 ± 5%, and 64.2 ± 3%, respectively; P < 0.001; and wiVD: 46.2 ± 6%, 51.3 ± 5%, and 56.6 ± 3%, respectively; P < 0.001). For differentiating between glaucoma and healthy eyes, the age-adjusted AUROC was highest for wiVD (0.94), followed by RNFL thickness (0.92) and cpVD (0.83). The AUROCs for differentiating between healthy and glaucoma suspect eyes were highest for wiVD (0.70), followed by cpVD (0.65) and RNFL thickness (0.65). Conclusions Optical coherence tomography angiography vessel density had similar diagnostic accuracy to RNFL thickness measurements for differentiating between healthy and glaucoma eyes. These results suggest that OCT-A measurements reflect damage to tissues relevant to the pathophysiology of OAG. PMID:27409505

Structure-function correlations using scanning laser polarimetry in primary angle-closure glaucoma and primary open-angle glaucoma.

PubMed

Lee, Pei-Jung; Liu, Catherine Jui-Ling; Wojciechowski, Robert; Bailey-Wilson, Joan E; Cheng, Ching-Yu

2010-05-01

To assess the correlations between retinal nerve fiber layer (RNFL) thickness measured with scanning laser polarimetry and visual field (VF) sensitivity in primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). Prospective, comparative, observational cases series. Fifty patients with POAG and 56 patients with PACG were examined using scanning laser polarimetry with variable corneal compensation (GDx VCC; Laser Diagnostic Technologies, Inc.) and Humphrey VF analyzer (Carl Zeiss Meditec, Inc.) between August 2005 and July 2006 at Taipei Veterans General Hospital. Correlations between RNFL thickness and VF sensitivity, expressed as mean sensitivity in both decibel and 1/Lambert scales, were estimated by the Spearman rank correlation coefficient (r(s)) and multivariate median regression models (pseudo R(2)). The correlations were determined globally and for 6 RNFL sectors and their corresponding VF regions. The correlation between RNFL thickness and mean sensitivity (in decibels) was weaker in the PACG group (r(s) = 0.38; P = .004; pseudo R(2) = 0.17) than in the POAG group (r(s) = 0.51; P < .001; pseudo R(2) = .31), but the difference in the magnitude of correlation was not significant (P = .42). With Bonferroni correction, the structure-function correlation was significant in the superotemporal (r(s) = 0.62), superonasal (r(s) = 0.56), inferonasal (r(s) = 0.53), and inferotemporal (r(s) = 0.50) sectors in the POAG group (all P < .001), whereas it was significant only in the superotemporal (r(s) = 0.53) and inferotemporal (r(s) = 0.48) sectors in the PACG group (both P < .001). The results were similar when mean sensitivity was expressed as 1/Lambert scale. Both POAG and PACG eyes had moderate structure-function correlations using scanning laser polarimetry. Compared with eyes with POAG, fewer RNFL sectors have significant structure-function correlations in eyes with PACG. Copyright 2010 Elsevier Inc. All rights reserved.

Long-term structural retinal changes in patients with optic neuritis related to multiple sclerosis

PubMed Central

Andersen, Maria Rene; Roar, Malte; Sejbaek, Tobias; Illes, Zsolt; Grauslund, Jakob

2017-01-01

Purpose To evaluate the long-term structural and functional outcome in patients with multiple sclerosis (MS) with and without a history of optic neuritis (ON). Methods This was a cross-sectional study of 82 patients diagnosed with MS between 2000 and 2006 from a tertiary hospital center in Denmark. Patients gave a self-reported history of ON, and functional (visual acuity and color vision) and structural (spectra domain optical coherence tomography) markers of vision were tested. Results Median age and MS duration at the time of the clinical examination were 49.9 years (range 30.7–72.6 years) and 13 years (range 9–15 years), respectively. ON was not associated with impairment of visual acuity or color vision. Twenty-three patients had a history of ON in at least one eye. Compared to non-affected patients, these had a lower inferior (109 vs 113 μm, P=0.04) and temporal retinal nerve fiber layer (RNFL) thickness (56 vs 67 μm, P=0.01). In an age- and sex-adjusted logistic regression model, lower inferior and temporal RNFL were associated with a higher risk of ON (odds ratio [OR] 1.56 [95% confidence interval {CI} 1.01–2.41] and OR 1.74 [95% CI 1.10–2.77] per 10 μm decrement in RNFL thickness, respectively). Twenty patients had a history of ON in one eye. Compared to the non-affected eye, this eye had a lower RNFL (109 vs 115 μm, P=0.04) and a higher central retinal thickness/mean RNFL ratio (2.7 vs 2.4, P=0.04). Conclusion Although patients with long-term MS and a previous history of ON did not have any functional loss of vision, structural neurodegeneration could be demonstrated in the affected eye. PMID:28860702

Structural parameters associated with location of peaks of peripapillary retinal nerve fiber layer thickness in young healthy eyes.

PubMed

Yamashita, Takehiro; Asaoka, Ryo; Kii, Yuya; Terasaki, Hiroto; Murata, Hiroshi; Sakamoto, Taiji

2017-01-01

The location of the peaks of the circumpapillary retinal nerve fiber layer (cpRNFL) thickness is affected by several ocular parameters. In this study, we have generated equations that can determine the peaks of the cpRNFL. This study was a prospective, observational, cross sectional study of 118 healthy right eyes. The axial length, optic disc tilt, superiortemporal (ST)- and inferiortemporal (IT)-peaks of the cpRNFL thickness, and angles of the ST and IT retinal arteries (RA) and veins (RV) were determined. The correlations between the location of the ST- and IT-peaks and ocular structural parameters and the sex, body height and weight were calculated. The best fit equations to generate the location of the ST/IT-peaks were determined using corrected-Akaike Information Criteria. The location of the ST-peak was 0.72+(0.40 x ST-RA)+(0.27 x ST-RV)+(0.14 x height)-(0.47 x papillo-macular-position)-(0.11 x disc tilt) with a coefficient of correlation of 0.61 (P<0.0001). The location of the IT-peak was 21.88+(0.53 x IT-RA)+(0.15 x IT-RV)+(0.041 x corneal thickness)-(1.00 x axial length) with a coefficient of correlation of 0.59 (P<0.0001). The location of ST/IT peaks is determined by different parameters of the ocular structure. These equations allow clinicians to obtain an accurate location of the peaks for a more accurate diagnosis of glaucoma.

Scintillating fibres coupled to silicon photomultiplier prototypes for fast beam monitoring and thin timing detectors

NASA Astrophysics Data System (ADS)

Papa, A.; Kettle, P.-R.; Ripiccini, E.; Rutar, G.

2016-07-01

Several scintillating fibre prototypes (single- and double-layers) made of 250 μm multi-clad square fibres coupled to silicon photomultiplier have been studied using electrons, positrons and muons at different energies. Current measurements show promising results: already for a single fibre layer and minimum ionizing particles we obtain a detection efficiency ≥ 95 % (mean collected light/fibre ≈ 8 phe), a timing resolution of 550 ps/fibre and a foreseen spatial resolution < 100 μm, based on the achieved negligible optical cross-talk between fibres (< 1 %). We will also discuss the performances of a double-layer staggered prototype configuration, for which a full detection efficiency (≥ 99 %) has been measured together with a timing resolution of ≈ 400 ps for double hit events.

Analysis of Macular and Retinal Nerve Fiber Layer Thickness in Children with Refractory Amblyopia after Femtosecond Laser-assisted Laser In situ Keratomileusis: A Retrospective Study.

PubMed

Zhao, Peng-Fei; Zhou, Yue-Hua; Zhang, Jing; Wei, Wen-Bin

2017-09-20

Localized macular edema and retinal nerve fiber layer (RNFL) thinning have been reported shortly after laser in situ keratomileusis (LASIK) in adults. However, it is still unclear how LASIK affects the retina of children. This study aimed to investigate the macular retina and RNFL thickness in children with refractive amblyopia who underwent femtosecond laser-assisted LASIK (FS-LASIK). In this study, we included 56 eyes of 32 patients with refractive amblyopia who underwent FS-LASIK in our hospital from January 2012 to December 2016. Foveal (foveal center retinal, parafoveal retinal, and perifoveal), macular inner retinal (superior and inferior), and peripapillary RNFL thicknesses (superior, inferior, temporal, and nasal) were measured using Fourier-domain optical coherence tomography before surgery and 1 day, 3 days, and 1 week after surgery. We divided these patients into three groups based on their refractive error: High myopic group with 22 eyes (equivalent sphere, >6.00 D), mild myopic group with 19 eyes (equivalent sphere, 0-6.00 D), and hyperopic group with 15 eyes (equivalent sphere, >+0.50 D). We compared the macular retina and RNFL thickness before and after LASIK. A paired simple t-test was used for data analysis. One week after surgery, the visual acuity for all 56 eyes of the 32 patients reached their preoperative best-corrected vision. Visual acuity improved two lines or better for 31% of the patients. The residual refractive errors in 89% of the patients were within ±0.5 D. In the high myopic group, the foveal center retinal and parafoveal retinal thicknesses were thicker 1 day and 3 days after surgery than before surgery (t = 2.689, P = 0.012; t = 2.383, P = 0.018, respectively); no significant difference was found 1 week after surgery (P > 0.05). The foveal center retinal and parafoveal retinal thicknesses were greater 1 day after surgery than they were before surgery (P = 0.000 and P = 0.005, respectively) in the mild myopic and hyperopic groups. No significant difference was found 3 days or 1 week after surgery (P > 0.05). In all three groups, no significant difference was found in the macular inner retinal or peripapillary RNFL thickness 1 day, 3 days, or 1 week after surgery (P > 0.05). The foveal center retinal edema after FS-LASIK is mild and reversible in children, that mostly occurred in the high myopic group with no effect on the visual acuity, and is always relieved within 1 week.

Automated diagnosis of diabetic retinopathy and glaucoma using fundus and OCT images.

PubMed

Pachiyappan, Arulmozhivarman; Das, Undurti N; Murthy, Tatavarti Vsp; Tatavarti, Rao

2012-06-13

We describe a system for the automated diagnosis of diabetic retinopathy and glaucoma using fundus and optical coherence tomography (OCT) images. Automatic screening will help the doctors to quickly identify the condition of the patient in a more accurate way. The macular abnormalities caused due to diabetic retinopathy can be detected by applying morphological operations, filters and thresholds on the fundus images of the patient. Early detection of glaucoma is done by estimating the Retinal Nerve Fiber Layer (RNFL) thickness from the OCT images of the patient. The RNFL thickness estimation involves the use of active contours based deformable snake algorithm for segmentation of the anterior and posterior boundaries of the retinal nerve fiber layer. The algorithm was tested on a set of 89 fundus images of which 85 were found to have at least mild retinopathy and OCT images of 31 patients out of which 13 were found to be glaucomatous. The accuracy for optical disk detection is found to be 97.75%. The proposed system therefore is accurate, reliable and robust and can be realized.

Automated diagnosis of diabetic retinopathy and glaucoma using fundus and OCT images

PubMed Central

2012-01-01

We describe a system for the automated diagnosis of diabetic retinopathy and glaucoma using fundus and optical coherence tomography (OCT) images. Automatic screening will help the doctors to quickly identify the condition of the patient in a more accurate way. The macular abnormalities caused due to diabetic retinopathy can be detected by applying morphological operations, filters and thresholds on the fundus images of the patient. Early detection of glaucoma is done by estimating the Retinal Nerve Fiber Layer (RNFL) thickness from the OCT images of the patient. The RNFL thickness estimation involves the use of active contours based deformable snake algorithm for segmentation of the anterior and posterior boundaries of the retinal nerve fiber layer. The algorithm was tested on a set of 89 fundus images of which 85 were found to have at least mild retinopathy and OCT images of 31 patients out of which 13 were found to be glaucomatous. The accuracy for optical disk detection is found to be 97.75%. The proposed system therefore is accurate, reliable and robust and can be realized. PMID:22695250

Diagnostic Capability of Peripapillary Retinal Volume Measurements in Glaucoma.

PubMed

Simavli, Huseyin; Poon, Linda Yi-Chieh; Que, Christian J; Liu, Yingna; Akduman, Mustafa; Tsikata, Edem; de Boer, Johannes F; Chen, Teresa C

2017-06-01

To determine the diagnostic capability of spectral domain optical coherence tomography peripapillary retinal volume (RV) measurements. A total of 156 patients, 89 primary open-angle glaucoma and 67 normal subjects, were recruited. Spectral domain optical coherence tomography peripapillary RV was calculated for 4 quadrants using 3 annuli of varying scan circle diameters: outer circumpapillary annuli of circular grids 1, 2, and 3 (OCA1, OCA2, OCA3). Area under the receiver operating characteristic curves and pairwise comparisons of receiver operating characteristic (ROC) curves were performed to determine which quadrants were best for diagnosing primary open-angle glaucoma. The pairwise comparisons of the best ROC curves for RV and retinal nerve fiber layer (RNFL) were performed. The artifact rates were analyzed. Pairwise comparisons showed that the smaller annuli OCA1 and OCA2 had better diagnostic performance than the largest annulus OCA3 (P<0.05 for all quadrants). OCA1 and OCA2 had similar diagnostic performance, except for the inferior quadrant which was better for OCA1 (P=0.0033). The pairwise comparisons of the best ROC curves for RV and RNFL were not statistically significant. RV measurements had lower rates of artifacts at 7.4% while RNFL measurements had higher rates at 42.9%. Peripapillary RV measurements have excellent ability for diagnosing not only glaucoma patients but also a subset of early glaucoma patients. The inferior quadrant of peripapillary annulus OCA1 demonstrated the best diagnostic capability for both glaucoma and early glaucoma. The diagnostic ability of RV is comparable with that of RNFL parameters in glaucoma but with lower artifact rates.

Radial Peripapillary Capillary Network Visualized Using Wide-Field Montage Optical Coherence Tomography Angiography.

PubMed

Mase, Tomoko; Ishibazawa, Akihiro; Nagaoka, Taiji; Yokota, Harumasa; Yoshida, Akitoshi

2016-07-01

We quantitatively analyzed the features of a radial peripapillary capillary (RPC) network visualized using wide-field montage optical coherence tomography (OCT) angiography in healthy human eyes. Twenty eyes of 20 healthy subjects were recruited. En face 3 × 3-mm OCT angiograms of multiple locations in the posterior pole were acquired using the RTVue XR Avanti, and wide-field montage images of the RPC were created. To evaluate the RPC density, the montage images were binarized and skeletonized. The correlation between the RPC density and the retinal nerve fiber layer (RNFL) thickness measured by an OCT circle scan was investigated. The RPC at the temporal retina was detected as far as 7.6 ± 0.7 mm from the edge of the optic disc but not around the perifoveal area within 0.9 ± 0.1 mm of the fovea. Capillary-free zones beside the first branches of the arterioles were significantly (P < 0.0001) narrower than those beside the second ones. The RPC densities at 0.5, 2.5, and 5 mm from the optic disc edge were 13.6 ± 0.8, 11.9 ± 0.9, and 10.4 ± 0.9 mm-1. The RPC density also was correlated significantly (r = 0.64, P < 0.0001) with the RNFL thickness, with the greatest density in the inferotemporal region. Montage OCT angiograms can visualize expansion of the RPC network. The RPC is present in the superficial peripapillary retina in proportion to the RNFL thickness, supporting the idea that the RPC may be the vascular network primarily responsible for RNFL nourishment.

The Relation of White-on-White Standard Automated Perimetry, Short Wavelength Perimetry, and Optic Coherence Tomography Parameters in Ocular Hypertension.

PubMed

Başkan, Ceyda; Köz, Özlem G; Duman, Rahmi; Gökçe, Sabite E; Yarangümeli, Ahmet A; Kural, Gülcan

2016-12-01

The purpose of this study is to examine the demographics, clinical properties, and the relation between white-on-white standard automated perimetry (SAP), short wavelength automated perimetry (SWAP), and optical coherence tomographic (OCT) parameters of patients with ocular hypertension. Sixty-one eyes of 61 patients diagnosed with ocular hypertension in the Ankara Numune Education and Research Hospital ophthalmology unit between January 2010 and January 2011 were included in this study. All patients underwent SAP and SWAP tests with the Humphrey visual field analyser using the 30.2 full-threshold test. Retinal nerve fiber layers (RNFL) and optic nerve heads of patients were evaluated with Stratus OCT. Positive correlation was detected between SAP pattern standard deviation value and average intraocular pressure (P=0.017), maximum intraocular pressure (P=0.009), and vertical cup to disc (C/D) ratio (P=0.009). Positive correlation between SWAP median deviation value with inferior (P=0.032), nasal (P=0.005), 6 o'clock quadrant RNFL thickness (P=0.028), and Imax/Tavg ratio (P=0.023) and negative correlation with Smax/Navg ratio (P=0.005) were detected. There was no correlation between central corneal thickness and peripapillary RNFL thicknesses (P>0.05). There was no relation between SAP median deviation, pattern standard deviation values and RNFL thicknesses and optic disc parameters of the OCT. By contrast significant correlation between several SWAP parameters and OCT parameters were detected. SWAP appeared to outperform achromatic SAP when the same 30-2 method was used.

Electrophysiology and optical coherence tomography to evaluate Parkinson disease severity.

PubMed

Garcia-Martin, Elena; Rodriguez-Mena, Diego; Satue, Maria; Almarcegui, Carmen; Dolz, Isabel; Alarcia, Raquel; Seral, Maria; Polo, Vicente; Larrosa, Jose M; Pablo, Luis E

2014-02-04

To evaluate correlations between visual evoked potentials (VEP), pattern electroretinogram (PERG), and macular and retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and the severity of Parkinson disease (PD). Forty-six PD patients and 33 age and sex-matched healthy controls were enrolled, and underwent VEP, PERG, and OCT measurements of macular and RNFL thicknesses, and evaluation of PD severity using the Hoehn and Yahr scale to measure PD symptom progression, the Schwab and England Activities of Daily Living Scale (SE-ADL) to evaluate patient quality of life (QOL), and disease duration. Logistical regression was performed to analyze which measures, if any, could predict PD symptom progression or effect on QOL. Visual functional parameters (best corrected visual acuity, mean deviation of visual field, PERG positive (P) component at 50 ms -P50- and negative (N) component at 95 ms -N95- component amplitude, and PERG P50 component latency) and structural parameters (OCT measurements of RNFL and retinal thickness) were decreased in PD patients compared with healthy controls. OCT measurements were significantly negatively correlated with the Hoehn and Yahr scale, and significantly positively correlated with the SE-ADL scale. Based on logistical regression analysis, fovea thickness provided by OCT equipment predicted PD severity, and QOL and amplitude of the PERG N95 component predicted a lower SE-ADL score. Patients with greater damage in the RNFL tend to have lower QOL and more severe PD symptoms. Foveal thicknesses and the PERG N95 component provide good biomarkers for predicting QOL and disease severity.

Influence of cataract surgery on optical coherence tomography and neurophysiology measurements in patients with retinitis pigmentosa.

PubMed

Garcia-Martin, Elena; Rodriguez-Mena, Diego; Dolz, Isabel; Almarcegui, Carmen; Gil-Arribas, Laura; Bambo, Maria P; Larrosa, Jose M; Polo, Vicente; Pablo, Luis E

2013-08-01

To evaluate the effect of uncomplicated cataract phacoemulsification on the measurements of visual evoked potentials (VEP), pattern electroretinogram (PERG), and macular and retinal nerve fiber layer (RNFL) using 2 spectral-domain optical coherence tomography (OCT) instruments, the Cirrus OCT (Carl Zeiss Meditech) and Spectralis OCT (Heidelberg Engineering), in patients with retinitis pigmentosa (RP), and to assess the reliability of the OCT measurements before and after cataract surgery. Observational cross-sectional study. Thirty-five eyes of 35 patients with RP (20 men and 15 women, 45-66 years) who underwent cataract phacoemulsification were studied. At 1 month before and 1 month after surgery, visual acuity, VEP, PERG, and 3 repetitions of scans using the RNFL and macular analysis protocols of the Cirrus and Spectralis OCT instruments were performed. The differences in measurements between the 2 visits were analyzed. Repeatability of OCT measurements was evaluated by calculating the coefficients of variation. VEP amplitude, RNFL thicknesses provided by Cirrus and Spectralis, and macular measurements provided by Cirrus OCT differed between the 2 visits. VEP latency, PERG measurements, and macular thicknesses provided by the Spectralis OCT before surgery did not differ significantly from those after surgery. The OCT repeatability was better after surgery, with lower coefficients of variation for scans performed after surgical removal of the cataract. The nuclear, cortical, and posterior subcapsular types of cataracts did not show different repeatability. The presence of cataracts affects VEP amplitude, RNFL, and macular measurements performed with OCT in eyes with RP. Image repeatability significantly improves after cataract phacoemulsification. Copyright © 2013 Elsevier Inc. All rights reserved.

Association between the Frequency of Optic Disk Hemorrhage and Progression of NTG Related with the Initial Location of RNFL Defect.

PubMed

Cho, Hyun-Kyung; Lee, Min Gyu; Kee, Changwon

2018-06-12

This study aimed to investigate the association of the frequency of optic disk hemorrhage (DH) and progression of normal tension glaucoma (NTG) between each group based on the location of the initial retinal nerve fiber layer (RNFL) defect. In this retrospective, observational cohort study, 142 NTG patients who underwent more than 5 reliable visual field tests with initial superior hemifield (group 2, n = 51), inferior hemifield (group 1, n = 44), or both hemifield (group 3, n = 47) defects were included. The number of DHs was inspected in serial optic disk photographs by 2 different ophthalmologists. Progression rates, which are the slope of mean thresholds from the 52 points, were calculated using a linear mixed effect model. The mean follow-up period was 8.19 ± 3.30 years. DHs related with the initial RNFL defect occurred significantly more frequently in group 2 (35 in inferior hemifield) than in group 1 (6 in superior hemifield) (p = 0.009) or group 3 (6 in inferior hemifield) (p = 0.006). The progression rate in group 2 was significantly faster than in group 1 (p = 0.019) or the superior hemifield of group 3 (p = 0.001). The progression rate of subjects showing recurrent DH was significantly faster than those showing single DH from all groups (-0.5460 vs. -0.2867 dB/year, p = 0.0053). More careful examination and caution are required when NTG patients show recurrent DH in the inferior hemifield related to the initial RNFL defect. © 2018 S. Karger AG, Basel.

Structural changes of macula and optic disk of the fellow eye in patients with nonarteritic anterior ischemic optic neuropathy.

PubMed

Duman, R; Yavas, G F; Veliyev, I; Dogan, M; Duman, R

2018-05-10

The aim was to assess the ganglion cell complex (GCC) thickness, retinal nerve fiber layer (RNFL) thickness and optic disk features in the affected eyes (AE) and unaffected fellow eyes (FE) of subjects with unilateral nonarteritic anterior ischemic optic neuropathy (NAION) and to compare with healthy control eyes (CE) using spectral domain-optical coherence tomography (SD-OCT). This study included 28 patients and age, sex and refraction-matched 28 control subjects. Mean GCC thickness and peripapillary RNFL thickness in four quadrants measured by cirrus SD-OCT were evaluated in both AE and FE of patients and CE. In addition, optic disk measurements obtained with OCT were evaluated. Mean GCC thickness was significantly lower in AE compared with both FE and CE (P < 0.001), and mean GCC thickness in FE was significantly lower than CE (P = 0.022). In addition, mean RNFL thickness in superior and nasal quadrants significantly decreased in FE compared with CE (P = 0.020 and 0.010, respectively). Furthermore, AE had significantly greater optic disk cupping compared with both FE and CE (P < 0.001). GCC and RNFL thickness decreased significantly at late stages of NAION, in both AE and FE compared with CE, suggesting that some subclinical structural changes may occur in FE despite lack of obvious visual symptoms. In addition, there was no significant difference in optic disk features between the CE and FE. And significantly greater optic disk cupping in the AE compared with both FE and CE supports the acquired enlargement of cupping after the onset of NAION.

Relevance Vector Machine and Support Vector Machine Classifier Analysis of Scanning Laser Polarimetry Retinal Nerve Fiber Layer Measurements

PubMed Central

Bowd, Christopher; Medeiros, Felipe A.; Zhang, Zuohua; Zangwill, Linda M.; Hao, Jiucang; Lee, Te-Won; Sejnowski, Terrence J.; Weinreb, Robert N.; Goldbaum, Michael H.

2010-01-01

Purpose To classify healthy and glaucomatous eyes using relevance vector machine (RVM) and support vector machine (SVM) learning classifiers trained on retinal nerve fiber layer (RNFL) thickness measurements obtained by scanning laser polarimetry (SLP). Methods Seventy-two eyes of 72 healthy control subjects (average age = 64.3 ± 8.8 years, visual field mean deviation =−0.71 ± 1.2 dB) and 92 eyes of 92 patients with glaucoma (average age = 66.9 ± 8.9 years, visual field mean deviation =−5.32 ± 4.0 dB) were imaged with SLP with variable corneal compensation (GDx VCC; Laser Diagnostic Technologies, San Diego, CA). RVM and SVM learning classifiers were trained and tested on SLP-determined RNFL thickness measurements from 14 standard parameters and 64 sectors (approximately 5.6° each) obtained in the circumpapillary area under the instrument-defined measurement ellipse (total 78 parameters). Tenfold cross-validation was used to train and test RVM and SVM classifiers on unique subsets of the full 164-eye data set and areas under the receiver operating characteristic (AUROC) curve for the classification of eyes in the test set were generated. AUROC curve results from RVM and SVM were compared to those for 14 SLP software-generated global and regional RNFL thickness parameters. Also reported was the AUROC curve for the GDx VCC software-generated nerve fiber indicator (NFI). Results The AUROC curves for RVM and SVM were 0.90 and 0.91, respectively, and increased to 0.93 and 0.94 when the training sets were optimized with sequential forward and backward selection (resulting in reduced dimensional data sets). AUROC curves for optimized RVM and SVM were significantly larger than those for all individual SLP parameters. The AUROC curve for the NFI was 0.87. Conclusions Results from RVM and SVM trained on SLP RNFL thickness measurements are similar and provide accurate classification of glaucomatous and healthy eyes. RVM may be preferable to SVM, because it provides a Bayesian-derived probability of glaucoma as an output. These results suggest that these machine learning classifiers show good potential for glaucoma diagnosis. PMID:15790898

A preliminary study on puncture resistances of top and bottom layers of multi-layered needlepunched nonwoven geotextiles

NASA Astrophysics Data System (ADS)

Alan, G.; Tercan, M.

2017-10-01

Needlepunched nonwoven textiles are commonly used as geotextiles for various applications. Considering both environmental and economical benefits, utilization of recycled fibres in nonwoven geotextiles has become an attractive issue. Within this scope, the aim of this study is to evaluate the puncture resistance performances of top and bottom layers of multi-layered needle punched nonwovens made of recycled fibres to be used as membrane protective geotextiles by comparing them with those of made from polypropylene and polyester fibres. Puncture resistance results indicated that nonwovens made of recycled fibres demonstrated good performances at this preliminary stage.

Virtual Averaging Making Nonframe-Averaged Optical Coherence Tomography Images Comparable to Frame-Averaged Images.

PubMed

Chen, Chieh-Li; Ishikawa, Hiroshi; Wollstein, Gadi; Bilonick, Richard A; Kagemann, Larry; Schuman, Joel S

2016-01-01

Developing a novel image enhancement method so that nonframe-averaged optical coherence tomography (OCT) images become comparable to active eye-tracking frame-averaged OCT images. Twenty-one eyes of 21 healthy volunteers were scanned with noneye-tracking nonframe-averaged OCT device and active eye-tracking frame-averaged OCT device. Virtual averaging was applied to nonframe-averaged images with voxel resampling and adding amplitude deviation with 15-time repetitions. Signal-to-noise (SNR), contrast-to-noise ratios (CNR), and the distance between the end of visible nasal retinal nerve fiber layer (RNFL) and the foveola were assessed to evaluate the image enhancement effect and retinal layer visibility. Retinal thicknesses before and after processing were also measured. All virtual-averaged nonframe-averaged images showed notable improvement and clear resemblance to active eye-tracking frame-averaged images. Signal-to-noise and CNR were significantly improved (SNR: 30.5 vs. 47.6 dB, CNR: 4.4 vs. 6.4 dB, original versus processed, P < 0.0001, paired t -test). The distance between the end of visible nasal RNFL and the foveola was significantly different before (681.4 vs. 446.5 μm, Cirrus versus Spectralis, P < 0.0001) but not after processing (442.9 vs. 446.5 μm, P = 0.76). Sectoral macular total retinal and circumpapillary RNFL thicknesses showed systematic differences between Cirrus and Spectralis that became not significant after processing. The virtual averaging method successfully improved nontracking nonframe-averaged OCT image quality and made the images comparable to active eye-tracking frame-averaged OCT images. Virtual averaging may enable detailed retinal structure studies on images acquired using a mixture of nonframe-averaged and frame-averaged OCT devices without concerning about systematic differences in both qualitative and quantitative aspects.

Peripapillary vessel density changes in Leber's Hereditary Optic Neuropathy: a new biomarker.

PubMed

Balducci, Nicole; Cascavilla, Maria Lucia; Ciardella, Antonio; La Morgia, Chiara; Triolo, Giacinto; Parisi, Vincenzo; Bandello, Francesco; Sadun, Alfredo A; Carelli, Valerio; Barboni, Piero

2018-05-22

The contribution of the microvascular supply to the pathogenesis of Leber's Hereditary Optic Neuropathy (LHON) is poorly understood. We aimed at measuring the peripapillary capillary vessel density (VD) using optical coherence tomography angiography (OCT-A) at different stages of LHON. Prospective, cross-sectional, multicenter, observational study. Twenty-two LHON patients divided in 4 groups: unaffected mutation carriers (LHON-u); early subacute stage (LHON-e); late subacute stage (LHON-l); chronic stage (LHON-ch). OCT-A scans centered on the optic disc were obtained by spectral domain OCT system. VD, retinal nerve fiber layer (RNFL) and ganglion cell inner plexiform layer (GC-IPL) thickness were compared between groups. Significant VD changes were detected in every sector (p<0.0001). In LHON-e, the VD was reduced in the temporal sector compared with LHON-u and in the temporal and inferotemporal sectors compared with controls. In LHON-l, VD was reduced in whole, temporal, superotemporal and inferotemporal sectors compared with LHON-u and controls. In LHON-ch, the VD was reduced in all sectors compared to the other groups. An asynchronous pattern emerged in the temporal sector with VD changes occurring earlier than RNFL thickness changes and together with GC-IPL thinning. Significant peripapillary miscrovascular changes were detected over the different stages of LHON. Studying the vascular network separately from fibers revealed that microvascular changes in the temporal sector preceded the changes of RNFL and mirrored the GC-IPL changes. Measurements of the peripapillary vascular network may become a useful biomarker to monitor the disease process, evaluate therapeutic efficacy and elucidate pathophysiology. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Comparison of diagnostic capability of macular ganglion cell complex and retinal nerve fiber layer among primary open angle glaucoma, ocular hypertension, and normal population using Fourier-domain optical coherence tomography and determining their functional correlation in Indian population

PubMed Central

Barua, Nabanita; Sitaraman, Chitra; Goel, Sonu; Chakraborti, Chandana; Mukherjee, Sonai; Parashar, Hemandra

2016-01-01

Context: Analysis of diagnostic ability of macular ganglionic cell complex and retinal nerve fiber layer (RNFL) in glaucoma. Aim: To correlate functional and structural parameters and comparing predictive value of each of the structural parameters using Fourier-domain (FD) optical coherence tomography (OCT) among primary open angle glaucoma (POAG) and ocular hypertension (OHT) versus normal population. Setting and Design: Single centric, cross-sectional study done in 234 eyes. Materials and Methods: Patients were enrolled in three groups: POAG, ocular hypertensive and normal (40 patients in each group). After comprehensive ophthalmological examination, patients underwent standard automated perimetry and FD-OCT scan in optic nerve head and ganglion cell mode. The relationship was assessed by correlating ganglion cell complex (GCC) parameters with mean deviation. Results were compared with RNFL parameters. Statistical Analysis: Data were analyzed with SPSS, analysis of variance, t-test, Pearson's coefficient, and receiver operating curve. Results: All parameters showed strong correlation with visual field (P < 0.001). Inferior GCC had highest area under curve (AUC) for detecting glaucoma (0.827) in POAG from normal population. However, the difference was not statistically significant (P > 0.5) when compared with other parameters. None of the parameters showed significant diagnostic capability to detect OHT from normal population. In diagnosing early glaucoma from OHT and normal population, only inferior GCC had statistically significant AUC value (0.715). Conclusion: In this study, GCC and RNFL parameters showed equal predictive capability in perimetric versus normal group. In early stage, inferior GCC was the best parameter. In OHT population, single day cross-sectional imaging was not valuable. PMID:27221682

Virtual Averaging Making Nonframe-Averaged Optical Coherence Tomography Images Comparable to Frame-Averaged Images

PubMed Central

Chen, Chieh-Li; Ishikawa, Hiroshi; Wollstein, Gadi; Bilonick, Richard A.; Kagemann, Larry; Schuman, Joel S.

2016-01-01

Purpose Developing a novel image enhancement method so that nonframe-averaged optical coherence tomography (OCT) images become comparable to active eye-tracking frame-averaged OCT images. Methods Twenty-one eyes of 21 healthy volunteers were scanned with noneye-tracking nonframe-averaged OCT device and active eye-tracking frame-averaged OCT device. Virtual averaging was applied to nonframe-averaged images with voxel resampling and adding amplitude deviation with 15-time repetitions. Signal-to-noise (SNR), contrast-to-noise ratios (CNR), and the distance between the end of visible nasal retinal nerve fiber layer (RNFL) and the foveola were assessed to evaluate the image enhancement effect and retinal layer visibility. Retinal thicknesses before and after processing were also measured. Results All virtual-averaged nonframe-averaged images showed notable improvement and clear resemblance to active eye-tracking frame-averaged images. Signal-to-noise and CNR were significantly improved (SNR: 30.5 vs. 47.6 dB, CNR: 4.4 vs. 6.4 dB, original versus processed, P < 0.0001, paired t-test). The distance between the end of visible nasal RNFL and the foveola was significantly different before (681.4 vs. 446.5 μm, Cirrus versus Spectralis, P < 0.0001) but not after processing (442.9 vs. 446.5 μm, P = 0.76). Sectoral macular total retinal and circumpapillary RNFL thicknesses showed systematic differences between Cirrus and Spectralis that became not significant after processing. Conclusion The virtual averaging method successfully improved nontracking nonframe-averaged OCT image quality and made the images comparable to active eye-tracking frame-averaged OCT images. Translational Relevance Virtual averaging may enable detailed retinal structure studies on images acquired using a mixture of nonframe-averaged and frame-averaged OCT devices without concerning about systematic differences in both qualitative and quantitative aspects. PMID:26835180

Optimum stacking sequence design of laminated composite circular plates with curvilinear fibres by a layer-wise optimization method

NASA Astrophysics Data System (ADS)

Guenanou, A.; Houmat, A.

2018-05-01

The optimum stacking sequence design for the maximum fundamental frequency of symmetrically laminated composite circular plates with curvilinear fibres is investigated for the first time using a layer-wise optimization method. The design variables are two fibre orientation angles per layer. The fibre paths are constructed using the method of shifted paths. The first-order shear deformation plate theory and a curved square p-element are used to calculate the objective function. The blending function method is used to model accurately the geometry of the circular plate. The equations of motion are derived using Lagrange's method. The numerical results are validated by means of a convergence test and comparison with published values for symmetrically laminated composite circular plates with rectilinear fibres. The material parameters, boundary conditions, number of layers and thickness are shown to influence the optimum solutions to different extents. The results should serve as a benchmark for optimum stacking sequences of symmetrically laminated composite circular plates with curvilinear fibres.

Neuro-ophthalmologic evaluation, quality of life, and functional disability in patients with MS.

PubMed

Garcia-Martin, Elena; Rodriguez-Mena, Diego; Herrero, Raquel; Almarcegui, Carmen; Dolz, Isabel; Martin, Jesus; Ara, Jose R; Larrosa, Jose M; Polo, Vicente; Fernández, Javier; Pablo, Luis E

2013-07-02

To evaluate correlations between longitudinal changes in neuro-ophthalmologic measures and quality of life (QOL) and disability in patients with multiple sclerosis (MS), using optical coherence tomography (OCT), visual evoked potentials (VEP), and visual field examination. Fifty-four patients with relapsing-remitting MS were enrolled in this study and underwent Multiple Sclerosis Quality of Life questionnaire (54 items) (MSQOL-54) and Expanded Disability Status Scale (EDSS) evaluation, as well as complete neuro-ophthalmologic examination including visual field testing and retinal nerve fiber layer (RNFL) measurements using Cirrus and Spectralis OCT and VEP. All patients were re-evaluated at 12, 24, and 36 months. Logistical regression was performed to analyze which measures, if any, could predict QOL. Overall, RNFL thickness results at the baseline evaluation were significantly different from those at 3 years (p ≤ 0.05), but there were no differences in functional measures (visual acuity, contrast sensitivity, color vision, visual field, and VEP). A reduced MSQOL-54 score was associated with an increase in EDSS score and a decrease in both functional and structural parameters. Patients with longer MS duration presented with a lower MSQOL-54 score (reduction in QOL). Patients with progressive axonal loss as seen in RNFL results had a lower QOL and more functional disability.

Mathematical modelling of cell layer growth in a hollow fibre bioreactor.

PubMed

Chapman, Lloyd A C; Whiteley, Jonathan P; Byrne, Helen M; Waters, Sarah L; Shipley, Rebecca J

2017-04-07

Generating autologous tissue grafts of a clinically useful volume requires efficient and controlled expansion of cell populations harvested from patients. Hollow fibre bioreactors show promise as cell expansion devices, owing to their potential for scale-up. However, further research is required to establish how to specify appropriate hollow fibre bioreactor operating conditions for expanding different cell types. In this study we develop a simple model for the growth of a cell layer seeded on the outer surface of a single fibre in a perfused hollow fibre bioreactor. Nutrient-rich culture medium is pumped through the fibre lumen and leaves the bioreactor via the lumen outlet or passes through the porous fibre walls and cell layer, and out via ports on the outer wall of the extra-capillary space. Stokes and Darcy equations for fluid flow in the fibre lumen, fibre wall, cell layer and extra-capillary space are coupled to reaction-advection-diffusion equations for oxygen and lactate transport through the bioreactor, and to a simple growth law for the evolution of the free boundary of the cell layer. Cells at the free boundary are assumed to proliferate at a rate that increases with the local oxygen concentration, and to die and detach from the layer if the local fluid shear stress or lactate concentration exceed critical thresholds. We use the model to predict operating conditions that maximise the cell layer growth for different cell types. In particular, we predict the optimal flow rate of culture medium into the fibre lumen and fluid pressure imposed at the lumen outlet for cell types with different oxygen demands and fluid shear stress tolerances, and compare the growth of the cell layer when the exit ports on the outside of the bioreactor are open with that when they are closed. Model simulations reveal that increasing the inlet flow rate and outlet fluid pressure increases oxygen delivery to the cell layer and, therefore, the growth rate of cells that are tolerant to high shear stresses, but may be detrimental for shear-sensitive cells. The cell layer growth rate is predicted to increase, and be less sensitive to the lactate tolerance of the cells, when the exit ports are opened, as the radial flow through the bioreactor is enhanced and the lactate produced by the cells cleared more rapidly from the cell layer. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Retinal Parameters as Compared with Head Circumference, Height, Weight, and Body Mass Index in Children in Kenya and Bhutan.

PubMed

Grundy, Sara J; Tshering, Lhab; Wanjala, Stanley W; Diamond, Megan B; Audi, Martin S; Prasad, Sashank; Shinohara, Russell T; Rogo, Debora; Wangmo, Dechen; Wangdi, Ugyen; Aarayang, Abi; Tshering, Thukten; Burke, Thomas F; Mateen, Farrah J

2018-06-11

The retina shares embryological derivation with the brain and may provide a new measurement of overall growth status, especially useful in resource-limited settings. Optical coherence tomography (OCT) provides detailed quantification of retinal structures. We enrolled community-dwelling children ages 3-11 years old in Siaya, Kenya and Thimphu, Bhutan in 2016. We measured head circumference (age < 5 years only), height, and weight, and standardized these by age and gender. Research staff performed OCT ( iScan ; Optovue, Inc., Fremont, CA), measuring the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) thicknesses. A neuro-ophthalmologist performed quality control for centration, motion artifact, and algorithm-derived quality scores. Generalized estimating equations were used to determine the relationship between anthropometric and retinal measurements. Two hundred and fifty-eight children (139 females, average age 6.4 years) successfully completed at least one retinal scan, totaling 1,048 scans. Nine hundred and twenty-two scans (88.0%) were deemed usable. Fifty-three of the 258 children (20.5%) were able to complete all six scans. Kenyan children had a thinner average GCC ( P < 0.001) than Bhutanese children after adjustment for age and gender, but not RNFL ( P = 0.70). In models adjusting for age, gender, and study location, none of standardized height, weight, and body mass index (BMI) were statistically significantly associated with RNFL or GCC. We determined that OCT is feasible in some children in resource-limited settings, particularly those > 4 years old, using the iScan device. We found no evidence for GCC or RNFL as a proxy for height-, weight-, or BMI-for-age. The variation in mean GCC thickness in Asian versus African children warrants further investigation.

Effect of scan quality on diagnostic accuracy of spectral-domain optical coherence tomography in glaucoma.

PubMed

Rao, Harsha L; Addepalli, Uday K; Yadav, Ravi K; Senthil, Sirisha; Choudhari, Nikhil S; Garudadri, Chandra S

2014-03-01

To evaluate the effect of scan quality on the diagnostic accuracies of optic nerve head (ONH), retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) parameters of spectral-domain optical coherence tomography (SD OCT) in glaucoma. Cross-sectional study. Two hundred fifty-two eyes of 183 control subjects (mean deviation [MD]: -1.84 dB) and 207 eyes of 159 glaucoma patients (MD: -7.31 dB) underwent ONH, RNFL, and GCC scanning with SD OCT. Scan quality of SD OCT images was based on signal strength index (SSI) values. Influence of SSI on diagnostic accuracy of SD OCT was evaluated by receiver operating characteristic (ROC) regression. Diagnostic accuracies of all SD OCT parameters were better when the SSI values were higher. This effect was statistically significant (P < .05) for ONH and RNFL but not for GCC parameters. In mild glaucoma (MD of -5 dB), area under ROC curve (AUC) for rim area, average RNFL thickness, and average GCC thickness parameters improved from 0.651, 0.678, and 0.726, respectively, at an SSI value of 30 to 0.873, 0.962, and 0.886, respectively, at an SSI of 70. AUCs of the same parameters in advanced glaucoma (MD of -15 dB) improved from 0.747, 0.890, and 0.873, respectively, at an SSI value of 30 to 0.922, 0.994, and 0.959, respectively, at an SSI of 70. Diagnostic accuracies of SD OCT parameters in glaucoma were significantly influenced by the scan quality even when the SSI values were within the manufacturer-recommended limits. These results should be considered while interpreting the SD OCT scans for glaucoma. Copyright © 2014 Elsevier Inc. All rights reserved.

Diagnostic Capability of Peripapillary Retinal Thickness in Glaucoma Using 3D Volume Scans

PubMed Central

Simavli, Huseyin; Que, Christian John; Akduman, Mustafa; Rizzo, Jennifer L.; Tsikata, Edem; de Boer, Johannes F.; Chen, Teresa C.

2015-01-01

Purpose To determine the diagnostic capability of spectral domain optical coherence tomography (SD-OCT) peripapillary retinal thickness (RT) measurements from 3-dimensional (3D) volume scans for primary open angle glaucoma (POAG). Design Cross-sectional study. Methods Setting Institutional Study population 156 patients (89 POAG and 67 normal subjects) Observation procedures One eye of each subject was included. SD-OCT peripapillary RT values from 3D volume scans were calculated for four quadrants of three different sized annuli. Peripapillary retinal nerve fiber layer (RNFL) thickness values were also determined. Main outcome measures Area under the receiver operating characteristic curve (AUROC) values, sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios. Results The top five RT AUROCs for all glaucoma patients and for a subset of early glaucoma patients were for the inferior quadrant of outer circumpapillary annulus of circular grid (OCA) 1 (0.959, 0.939), inferior quadrant of OCA2 (0.945, 0.921), superior quadrant of OCA1 (0.890, 0.811), inferior quadrant of OCA3 (0.887, 0.854), and superior quadrant of OCA2 (0.879, 0.807). Smaller RT annuli OCA1 and OCA2 consistently showed better diagnostic performance than the larger RT annulus OCA3. For both RNFL and RT measurements, best AUROC values were found for inferior RT OCA1 and OCA2, followed by inferior and overall RNFL thickness. Conclusion Peripapillary RT measurements from 3D volume scans showed excellent diagnostic performance for detecting both glaucoma and early glaucoma patients. Peripapillary RT values have the same or better diagnostic capability compared to peripapillary RNFL thickness measurements, while also having fewer algorithm errors. PMID:25498354

Structure-Function Analysis of Nonarteritic Anterior Ischemic Optic Neuropathy and Age-Related Differences in Outcome.

PubMed

Sun, Ming-Hui; Liao, Yaping Joyce

2017-09-01

The optic nerve head is vulnerable to ischemia leading to anterior ischemic optic neuropathy (AION), the most common acute optic neuropathy in those older than 50 years of age. We performed a cross-sectional study of 55 nonarteritic anterior ischemic optic neuropathy (NAION) eyes in 34 patients to assess clinical outcome and perform structure-function correlations. The peak age of NAION onset was between 50 and 55 years. Sixty-seven percent of patients presented with their first event between the ages of 40 and 60 years, and 32% presented at ≤50 years. Those with NAION onset at age ≤50 years did not have significantly better visual outcome per logMAR visual acuity, automated perimetric mean deviation (PMD) or optical coherence tomography (OCT) measurements. Kaplan-Meier survival curve and multivariate Cox proportional regression analysis showed that age >50 years at NAION onset was associated with greater risk of second eye involvement, with hazard ratio of 20. Older age at onset was significantly correlated with greater thinning of the ganglion cell complex (GCC) (P = 0.022) but not with logMAR visual acuity, PMD, or thinning of retinal nerve fiber layer (RNFL). Using area under receiver operating characteristic curve analyses, we found that thinning of RNFL and GCC was best able to predict visual outcome, and that mean RNFL thickness >65 μm or macular GCC thickness >55 μm significantly correlated with good visual field outcome. We showed that NAION onset at age >50 years had a greater risk of second eye involvement. Patients with OCT mean RNFL thickness >65 μm and mean macular ganglion cell complex thickness >55 μm had better visual outcomes.

Glaucomatous Retinal Nerve Fiber Layer Thickness Loss is associated with Slower Reaction Times under a Divided Attention Task

PubMed Central

Tatham, Andrew J.; Boer, Erwin R.; Rosen, Peter N.; Penna, Mauro Della; Meira-Freitas, Daniel; Weinreb, Robert N.; Zangwill, Linda M.; Medeiros, Felipe A.

2014-01-01

Purpose To examine the relationship between glaucomatous structural damage and ability to divide attention during simulated driving. Design Cross-sectional observational study. Methods Setting Hamilton Glaucoma Center, University of California San Diego. Patient Population 158 subjects from the Diagnostic Innovations in Glaucoma Study, including 82 with glaucoma and 76 similarly aged controls. Observation Procedure Ability to divide attention was investigated by measuring reaction times to peripheral stimuli (at low, medium or high contrast) while concomitantly performing a central driving task (car following or curve negotiation). All subjects had standard automated perimetry (SAP) and optical coherence tomography was used to measured retinal nerve fiber (RNFL) thickness. Cognitive ability was assessed using the Montreal Cognitive Assessment and subjects completed a driving history questionnaire. Main outcome measures Reaction times to the driving simulator divided attention task. Results The mean reaction times to the low contrast stimulus were 1.05 s and 0.64 s in glaucoma and controls respectively during curve negotiation (P <0.001), and 1.19 s and 0.77 s (P = 0.025) respectively during car following. There was a non-linear relationship between reaction times and RNFL thickness in the better eye. RNFL thickness remained significantly associated with reaction times even after adjusting for age, SAP mean deviation in the better eye, cognitive ability and central driving task performance. Conclusions Although worse SAP sensitivity was associated with worse ability to divide attention, RNFL thickness measurements provided additional information. Information from structural tests may improve our ability to determine which patients are likely to have problems performing daily activities, such as driving. PMID:25068641

Discrepancy between structural and functional visual recovery in patients after trans-sphenoidal pituitary adenoma resection.

PubMed

Qiao, Nidan; Ye, Zhao; Shou, Xuefei; Wang, Yongfei; Li, Shiqi; Wang, Min; Zhao, Yao

2016-12-01

The relationship between functional and structural measurements is of fundamental importance in monitoring treatment and progression in patients with pituitary adenoma. In the present study, we examined the association between longitudinal changes in standard automated perimetry (SAP), retinal nerve fiber layer (RNFL) thickness and multifocal visual evoked potential (mfVEP) amplitude after transsphenoidal surgery. Thirty patients with pituitary adenoma were recruited from Huashan Hospital between September 2010 and January 2014. The examination included pupil examination, anterior and posterior segment examination, SAP, RNFL and mfVEP. At three months and nine months after transsphenoid surgery, follow-up measurements were conducted in twenty-three patients, and at 18 months after surgery, the same examinations were performed in seven patients. The average age of patients was 42.6±12.1years, with 23 males and 7 females. The mean score of SAP improved significantly: 1.75 before surgery; 0.62 at three months after surgery (p=0.00) and 0.50 at nine months after surgery (p=0.00). No significant improvement in RNFL thickness was observed at three months or nine months after surgery. The mean score of mfVEP also improved significantly: 0.85 before surgery; 0.53 at three months (p=0.00) and 0.38 at nine months after surgery (P=0.00). No statistical difference was observed in the outcome of patients at nine months of follow-up and 18 months of follow-up. Visual field and mfVEP recovery with unchanged RNFL thickness was observed in patients after transsphenoid pituitary adenoma resection. Copyright © 2016. Published by Elsevier B.V.

Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis.

PubMed

Kolbe, Scott C; van der Walt, Anneke; Butzkueven, Helmut; Klistorner, Alexander; Egan, Gary F; Kilpatrick, Trevor J

2016-01-01

Previous studies have reported diffusion tensor imaging (DTI) changes within the optic radiations of patients after optic neuritis (ON). We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1). We measured DTI parameters [fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of -2.6% per annum (control = -0.51%; p = 0.006). Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R = 0.450, p = 0.006; RD: R = -0.428, p = 0.009; MD: R = -0.365, p = 0.029). In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R = 0.489, p = 0.039). In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage.

Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis

PubMed Central

van der Walt, Anneke; Butzkueven, Helmut; Klistorner, Alexander; Egan, Gary F.; Kilpatrick, Trevor J.

2016-01-01

Previous studies have reported diffusion tensor imaging (DTI) changes within the optic radiations of patients after optic neuritis (ON). We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1). We measured DTI parameters [fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of −2.6% per annum (control = −0.51%; p = 0.006). Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R = 0.450, p = 0.006; RD: R = −0.428, p = 0.009; MD: R = −0.365, p = 0.029). In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R = 0.489, p = 0.039). In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage. PMID:27555964

Towards a super-strainable paper using the Layer-by-Layer technique.

PubMed

Marais, Andrew; Utsel, Simon; Gustafsson, Emil; Wågberg, Lars

2014-01-16

The Layer-by-Layer technique was used to build a polyelectrolyte multilayer on the surface of pulp fibres. The treated fibres were then used to prepare paper sheets and the mechanical properties of these sheets were evaluated as a function of the number of bi-layers on the fibres. Two different systems were studied: polyethyleneimine (PEI)/nanofibrillated cellulose (NFC), and polyallylamine hydrochloride (PAH)/hyaluronic acid (HA). Model experiments using dual polarization interferometry and SiO₂ surfaces showed that the two systems gave different thicknesses for a given number of layers. The outer layer was found to be a key parameter in the PEI/NFC system, whereas it was less important in the PAH/HA system. The mechanical properties of the sheets made from the PAH/HA treated fibres were significantly greater than those made from untreated fibres, reaching 70 Nm/g in tensile index and 6.5% in strain at break. Such a modification could be very useful for 3D forming of paper, opening new perspectives in for example the packaging industry, with a renewable and biodegradable product as a potential substitute for some of the traditional oil-based plastics. Copyright © 2013 Elsevier Ltd. All rights reserved.

Incidence of and risk factors for glaucoma in lost-to-follow-up normal-tension glaucoma suspect patients.

PubMed

Lim, Jong Hoon; Park, Jun Sang; Lee, So Yeon; Hong, Young Jae

2016-05-25

To investigate the incidence and risk factors of glaucoma in normal-tension glaucoma (NTG) suspect patients who had been lost-to-follow-up for at least 24 months. Seventy-two eyes of 72 NTG suspect patients who returned to the hospital after at least 24 months of follow-up loss were enrolled in this study between January 2009 and June 2013. The data were collected retrospectively. The incidence of glaucoma was investigated using a comprehensive glaucoma evaluation in lost-to-follow-up NTG suspect patients. The patients were classified into the glaucoma group, who developed glaucoma during the study period, and the glaucoma suspect group, who did not, to analyse the risk factors for glaucoma. The number of patients who developed glaucoma was 7 (9.7 %) out of the 72 NTG suspect patients who had been mean lost-to-follow-up for 44 months. The rate of progression from suspected to glaucoma was 2.6 %/year. In the glaucoma group, the baseline intraocular pressure (IOP) was 18.43 ± 2.44 mmHg, and the average retinal nerve fiber layer (RNFL) thickness was 78.14 ± 7.60 μm; in the glaucoma suspect group, the baseline IOP was 14.95 ± 2.47 mmHg, and the average RNFL thickness was 92.55 ± 7.65 μm. The study results showed that the glaucoma group had higher baseline IOP and a thinner average RNFL (p = 0.003; p < 0.001). The results of the multivariable logistic regression analysis showed that the risk factors for glaucoma were high baseline IOP (OR = 1.63; p = 0.037) and a thin average RNFL (OR = 0.841; p = 0.004). The incidence of glaucoma in the lost-to-follow-up NTG suspect patients was 9.7 % for approximately 44 months, at a rate of 2.6 %/year. The risk factors for glaucoma in these patients were high baseline IOP and a thin average RNFL.

Analysis of Macular and Retinal Nerve Fiber Layer Thickness in Children with Refractory Amblyopia after Femtosecond Laser-assisted Laser In situ Keratomileusis: A Retrospective Study

PubMed Central

Zhao, Peng-Fei; Zhou, Yue-Hua; Zhang, Jing; Wei, Wen-Bin

2017-01-01

Background: Localized macular edema and retinal nerve fiber layer (RNFL) thinning have been reported shortly after laser in situ keratomileusis (LASIK) in adults. However, it is still unclear how LASIK affects the retina of children. This study aimed to investigate the macular retina and RNFL thickness in children with refractive amblyopia who underwent femtosecond laser-assisted LASIK (FS-LASIK). Methods: In this study, we included 56 eyes of 32 patients with refractive amblyopia who underwent FS-LASIK in our hospital from January 2012 to December 2016. Foveal (foveal center retinal, parafoveal retinal, and perifoveal), macular inner retinal (superior and inferior), and peripapillary RNFL thicknesses (superior, inferior, temporal, and nasal) were measured using Fourier-domain optical coherence tomography before surgery and 1 day, 3 days, and 1 week after surgery. We divided these patients into three groups based on their refractive error: High myopic group with 22 eyes (equivalent sphere, >6.00 D), mild myopic group with 19 eyes (equivalent sphere, 0–6.00 D), and hyperopic group with 15 eyes (equivalent sphere, >+0.50 D). We compared the macular retina and RNFL thickness before and after LASIK. A paired simple t-test was used for data analysis. Results: One week after surgery, the visual acuity for all 56 eyes of the 32 patients reached their preoperative best-corrected vision. Visual acuity improved two lines or better for 31% of the patients. The residual refractive errors in 89% of the patients were within ±0.5 D. In the high myopic group, the foveal center retinal and parafoveal retinal thicknesses were thicker 1 day and 3 days after surgery than before surgery (t = 2.689, P = 0.012; t = 2.383, P = 0.018, respectively); no significant difference was found 1 week after surgery (P > 0.05). The foveal center retinal and parafoveal retinal thicknesses were greater 1 day after surgery than they were before surgery (P = 0.000 and P = 0.005, respectively) in the mild myopic and hyperopic groups. No significant difference was found 3 days or 1 week after surgery (P > 0.05). In all three groups, no significant difference was found in the macular inner retinal or peripapillary RNFL thickness 1 day, 3 days, or 1 week after surgery (P > 0.05). Conclusions: The foveal center retinal edema after FS-LASIK is mild and reversible in children, that mostly occurred in the high myopic group with no effect on the visual acuity, and is always relieved within 1 week. PMID:28875960

The structure and function of the macula in patients with advanced retinitis pigmentosa.

PubMed

Vámos, Rita; Tátrai, Erika; Németh, János; Holder, Graham E; DeBuc, Delia Cabrera; Somfai, Gábor Márk

2011-10-28

To assess the structure and function of the macula in advanced retinitis pigmentosa (RP). Twenty-nine eyes of 22 patients with RP were compared against 17 control eyes. Time-domain optical coherence tomography (OCT) data were processed using OCTRIMA (optical coherence tomography retinal image analysis) as a means of quantifying commercial OCT system images. The thickness of the retinal nerve fiber layer (RNFL), ganglion cell layer and inner plexiform layer complex (GCL+IPL), inner nuclear layer and outer plexiform layer complex (INL+OPL), and the outer nuclear layer (ONL) were measured. Multifocal electroretinography (mfERG) was performed; two groups were formed based on the mfERG findings. Fourteen eyes had no detectable central retinal function (NCRF) on mfERG; detectable but abnormal retinal function (DRF) was present in the mfERG of the other 15 eyes. The thickness of the ONL in the central macular region was significantly less in the NCRF eyes compared with that in both DRF eyes and controls. The ONL was significantly thinner in the pericentral region in both patient groups compared with that in controls, whereas the thickness of the GCL+IPL and INL+OPL was significantly decreased only in the NCRF eyes. The RNFL in the peripheral region was significantly thicker, whereas the thickness of the GCL+IPL and ONL was significantly thinner in both patient groups compared with that in controls. The results are consistent with degeneration of the outer retina preceding inner retinal changes in RP. OCT image segmentation enables objective evaluation of retinal structural changes in RP, with potential use in the planning of therapeutic interventions and conceivably as an outcome measure.

The Structure and Function of the Macula in Patients with Advanced Retinitis Pigmentosa

PubMed Central

Vámos, Rita; Tátrai, Erika; Németh, János; Holder, Graham E.; DeBuc, Delia Cabrera

2011-01-01

Purpose. To assess the structure and function of the macula in advanced retinitis pigmentosa (RP). Methods. Twenty-nine eyes of 22 patients with RP were compared against 17 control eyes. Time-domain optical coherence tomography (OCT) data were processed using OCTRIMA (optical coherence tomography retinal image analysis) as a means of quantifying commercial OCT system images. The thickness of the retinal nerve fiber layer (RNFL), ganglion cell layer and inner plexiform layer complex (GCL+IPL), inner nuclear layer and outer plexiform layer complex (INL+OPL), and the outer nuclear layer (ONL) were measured. Multifocal electroretinography (mfERG) was performed; two groups were formed based on the mfERG findings. Fourteen eyes had no detectable central retinal function (NCRF) on mfERG; detectable but abnormal retinal function (DRF) was present in the mfERG of the other 15 eyes. Results. The thickness of the ONL in the central macular region was significantly less in the NCRF eyes compared with that in both DRF eyes and controls. The ONL was significantly thinner in the pericentral region in both patient groups compared with that in controls, whereas the thickness of the GCL+IPL and INL+OPL was significantly decreased only in the NCRF eyes. The RNFL in the peripheral region was significantly thicker, whereas the thickness of the GCL+IPL and ONL was significantly thinner in both patient groups compared with that in controls. Conclusions. The results are consistent with degeneration of the outer retina preceding inner retinal changes in RP. OCT image segmentation enables objective evaluation of retinal structural changes in RP, with potential use in the planning of therapeutic interventions and conceivably as an outcome measure. PMID:21948552

Retinal Tissue Thickness is Reduced in Diabetic Peripheral Neuropathy.

PubMed

Srinivasan, Sangeetha; Pritchard, Nicola; Vagenas, Dimitrios; Edwards, Katie; Sampson, Geoff P; Russell, Anthony W; Malik, Rayaz A; Efron, Nathan

2016-10-01

To investigate the relationship between diabetic peripheral neuropathy (DPN) and retinal tissue thickness. Full retinal thickness in the central retinal, parafoveal, and perifoveal zones and thickness of the ganglion cell complex and retinal nerve fiber layer (RNFL) were assessed in 193 individuals (84 with type 1 diabetes, 67 with type 2 diabetes, and 42 healthy controls) using spectral domain optical coherence tomography. Among those with diabetes, 44 had neuropathy defined using a modified neuropathy disability score recorded on a 0-10 scale. Multiple regression analysis was performed to investigate the relationship between diabetic neuropathy and retinal tissue thickness, adjusted for the presence of diabetic retinopathy (DR), age, sex, duration of diabetes, and HbA 1c levels. In individuals with diabetes, perifoveal thickness was inversely related to the severity of neuropathy (p < 0.05), when adjusted for age, sex, duration of diabetes, and HbA 1c levels. DR was associated with reduced thickness in parafovea (p < 0.01). The RNFL was thinner in individuals with greater degrees of neuropathy (p < 0.04). DPN is associated with structural compromise involving several retinal layers. This compromise may represent a threat to visual integrity and therefore warrants examination of functional correlates.

Retinal Structure of Birds of Prey Revealed by Ultra-High Resolution Spectral-Domain Optical Coherence Tomography

PubMed Central

Ruggeri, Marco; Major, James C.; McKeown, Craig; Knighton, Robert W.; Puliafito, Carmen A.

2010-01-01

Purpose. To reveal three-dimensional (3-D) information about the retinal structures of birds of prey in vivo. Methods. An ultra-high resolution spectral-domain optical coherence tomography (SD-OCT) system was built for in vivo imaging of retinas of birds of prey. The calibrated imaging depth and axial resolution of the system were 3.1 mm and 2.8 μm (in tissue), respectively. 3-D segmentation was performed for calculation of the retinal nerve fiber layer (RNFL) map. Results. High-resolution OCT images were obtained of the retinas of four species of birds of prey: two diurnal hawks (Buteo platypterus and Buteo brachyurus) and two nocturnal owls (Bubo virginianus and Strix varia). These images showed the detailed retinal anatomy, including the retinal layers and the structure of the deep and shallow foveae. The calculated thickness map showed the RNFL distribution. Traumatic injury to one bird's retina was also successfully imaged. Conclusions. Ultra-high resolution SD-OCT provides unprecedented high-quality 2-D and 3-D in vivo visualization of the retinal structures of birds of prey. SD-OCT is a powerful imaging tool for vision research in birds of prey. PMID:20554605

Resonance Tests on Glass Reinforced Plastic Composite Panels.

DTIC Science & Technology

1981-04-01

glass -- fibre woven roving and glass - fibre chopped strand mat. BP Cellobond A2785-CV resin was used to bond the glass fibre layers to the foam. A rib was...foam slabs were filled with putty. The differences between the panels were the number of layers of glass fibre used on each side, the density of the...ORGANISATION AERONAUTICAL RESEARCH LABORATORIES MELBOURNE, VICTORIA Structures Technical Memorandum 329 RESONANCE TESTS O GLASS REINFORCED PLASTIC

Finite Element Simulation of Aluminium/GFRP Fibre Metal Laminate under Tensile Loading

NASA Astrophysics Data System (ADS)

Merzuki, M. N. M.; Rejab, M. R. M.; Romli, N. K.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Salleh, Salwani Mohd

2018-03-01

The response of a fibre metal laminate (FML) model to the tensile loading is predicted through a computational approach. The FML consisted with layers of aluminum alloy and embedded with one layer of composite material, Glass fibre Reinforced Plastic (GFRP). The glass fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy. A compression moulding technique was used in the process of a FML fabrication. The aluminium has been roughen by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure behaviour of the FML under the tensile loading. The responses on the FML under the tensile loading were numerically performed. The FML was modelled and analysed by using Abaqus/CAE 6.13 version. Based on the experimental and FE data of the tensile, the ultimate tensile stress is 120 MPa where delamination and fibre breakage happened. A numerical model was developed and agreed well with the experimental results. The laminate has an inelastic respond to increase the tensile loads which due to the plasticity of the aluminium layers.

Use of woven glass fibres to reinforce a composite veneer. A fracture resistance and acoustic emission study.

PubMed

Vallittu, P K

2002-05-01

The aim of this study was to investigate the possibility to reinforce the mechanically interlocked veneer of a porcelain-fused-to-metal (PFM) crown by woven glass fibre. A simulated situation to repair a fractured porcelain veneer was used in the experimental test set-up. A brass jig made into the shape of a framework of PFM maxillary central incisor crown with a retentive area at the palatal side of the incisal edge was used. A veneer were made with a restorative hybrid composite on the brass jig (control group). In the test groups, one or two layers of woven polymer pre-impregnated glass fibres (thickness: 0.06 mm/layer) were used by pressing the fibre weaves to the surface of the brass jig. Restorative hybrid composite was applied on the glass fibre weaves. Five veneers were made for all groups and the veneers were not cemented on the test jig. The veneers were loaded from the incisal edge until fracture occurred. The force was measured simultaneously with an acoustic emission analysis (AE) of the fracture propagation. Fracture force values for control veneers were 121 N and for those reinforced with one layer of glass fibres 399 N and for those reinforced with two layers of glass fibres 744 N ANOVA revealed significant difference between the mean values (P=0.003). The AE analysis showed different fracture propagation for the unreinforced and glass fibre reinforced veneers. The results of this study suggests that by placing two layers of woven glass fibres on the retentively shaped metal framework of the PFM crown before applying the restorative composite, considerably higher fracture resistance for the veneer could be obtained.

Effect of TiN coating on microstructure of Tif/Al composite.

PubMed

Xiu, Z Y; Chen, G Q; Wang, M; Hussain, Murid

2013-02-01

In the present work, Ti fibre reinforced Al matrix composites (Ti(f)/Al) were fabricated by pressure infiltration method. In order to suppress the severe Ti-Al reaction and reduce the formation of brittle TiAl(3) phase, a TiN layer was coated on Ti fibres by an arc ion plating method before composite preparation. A thin TiN layer was coated on the Ti fibre surface, and the maximum and minimum thickness values of layer were about 3.5 and 1μm, respectively. Prefer orientation of TiN on (111) and (200) was found by XRD analysis. A thin and uniform TiAl(3) layer was observed in Ti(f)/Al composite. However, after coated with TiN layer, no significant reaction layer was found in (Ti(f)+TiN)/Al composite. Segregation of Mg element was found in Ti(f)/Al composite, and the presence of TiN layer showed little effect on this behaviour. Due to the large CTE difference between Ti fibre and Al matrix, high density dislocations were observed in the Al matrix. Meanwhile, fine dispersed Mg(2)Al(3) phases were also found in Al matrix. Ti fibre is mainly composed of α- and β-Ti. Small discontinuous needle-like TiAl(3) phases were detected at TiN/Al interface, which implies that the presence of TiN layer between the Ti fibre and Al matrix could effectively hinder the formation of TiAl(3) phases. Copyright © 2012 Elsevier Ltd. All rights reserved.

Ocular changes in primary hypothyroidism.

PubMed

Ozturk, Banu T; Kerimoglu, Hurkan; Dikbas, Oguz; Pekel, Hamiyet; Gonen, Mustafa S

2009-12-29

To determine the ocular changes related to hypothyrodism in newly diagnosed patients without orbitopathy. Thirty-three patients diagnosed to have primary overt hypothyroidism were enrolled in the study. All subjects were assigned to underwent central corneal thickness (CCT), anterior chamber volume, depth and angle measurements with the Scheimpflug camera (Pentacam, Oculus) and cup to disc ratio (C/D), mean retinal thickness and mean retinal nerve fiber layer (RNFL) thickness measurements with optical coherence tomography (OCT) in addition to ophthalmological examination preceeding the replacement therapy and at the 1(st), 3(rd )and 6(th )months of treatment. The mean age of the patients included in the study were 40.58 +/- 1.32 years. The thyroid hormone levels return to normal levels in all patients during the follow-up period, however the mean intraocular pressure (IOP) revealed no significant change. The mean CCT was 538.05 +/- 3.85 mu initially and demonstrated no statistically significant change as the anterior chamber volume, depth and angle measurements did. The mean C/D ratio was 0.29 +/- 0.03 and the mean retinal thickness was 255.83 +/- 19.49 mu initially and the treatment did not give rise to any significant change. The mean RNFL thickness was also stable during the control visits, so no statistically significant change was encountered. Neither hypothyroidism, nor its replacement therapy gave rise to any change of IOP, CCT, anterior chamber parameters, RNFL, retinal thickness and C/D ratio.

Evaluation of Central Macular Thickness and Retinal Nerve Fiber Layer Thickness using Spectral Domain Optical Coherence Tomography in a Tertiary Care Hospital

PubMed Central

Saini, VK; Gupta, Saroj; Sharma, Anjali

2014-01-01

ABSTRACT Purpose: To evaluate the normative data of macular thickness and retinal nerve fiber layer thickness (RNFL) among normal subjects using spectral domain optical coherence tomography (OCT). Materials and methods: Normal subjects presenting to a tertiary medical hospital were included in the study. All patient underwent clinical examination followed by study of macular thickness and RN FL thick ness by spectral domain Topc on OCT. The data was collected and analyzed for variations in gender and age. The data was also compared with available literature. Results: Total numbers of patients enrolled in the study were 154 (308 eyes). Numbers of males were 79 (158 eyes) and numbers of females were 75 (150 eyes). The mean age among males was 42.67 ± 12.15 years and mean age among females was 42.88 ± 11.73 years. Overall the mean mac ular thickness (central 1 mm zone) with SD - OCT was 241.75 ± 17.3 microns. The mean macular volume was 7.6 cu. mm ± 0.33. On analysis of the RNFL thickness, we observed that the RNFL was thickest in the inferior quadrant (138.58) followed by superior (122.30) nasal (116.32) and temporal quadrant (73.04). Gender-wise comparison of the data revealed no statistically significant difference for age, macular thickness parameters, volume and RFNL values except outer temporal thickness among males and females. No age-related difference was noted in the above parameters. On comparison with available norma tive data from India and elsewhere, we found significant variations with different machines. Conclusion: The study is the first to provide normative data using SD-OCT from central India. The data from spectral domain OCT correlated well with the values obtained from similar studies with SD - OCT. Values obtained from time domain OCT machines are different and are not comparable. How to cite this article: Agarwal P, Saini VK, Gupta S, Sharma A. Evaluation of Central Macular Thickness and Retinal Nerve Fiber Layer Thickness using Spectral Domain Optical Coherence Tomography in a Tertiary Care Hospital. J Curr Glaucoma Pract 2014;8(2):75-81. PMID:26997813

Evaluating the Marginal Integrity of Bulk Fill Fibre Reinforced Composites in Bio-mimetically Restored Tooth.

PubMed

Patnana, Arun Kumar; Vanga, V Narsimha Rao; Chandrabhatla, Srinivas Kumar

2017-06-01

Over the past years, composites in aesthetic dentistry are showing a considerable progress, but mechanical strength and polymerization shrinkage are the two main drawbacks, which limit their use in high stress bearing areas. To evaluate the marginal integrity of short glass fibre reinforced composite restorations, fibre reinforced composites with composite superficial layer, and fibre reinforced composites with underlying flowable composite layer. This study was done on twenty eight sound premolar teeth with standardized class V cavities restored under four groups as Group I: Particulate filler composite (Filtek Z 250 XT, 3M ESPE); Group II: Short glass fibre reinforced composite (everX Posterior, GC); Group III: Short glass fibre reinforced composite with an overlying layer of particulate filler composite; Group IV: Short glass fibre reinforced composite with an underlying layer of flowable composite (Filtek Z 250 XT, 3M ESPE). Test samples were immersed in a 2% methylene blue dye for 24 hours at 37°C and each tooth was sectioned bucco-lingually. Staining along the tooth restoration interface was recorded and results were analysed statistically using Independent sample t-test and Tukey's post-hoc one-way ANOVA. The results showed significant difference in the dye penetration between the restorative materials in the occlusal and gingival margins (p=0.02). Short fibre reinforced composites showed a statistically significant difference in the microleakage scores when compared with the particulate filler composites (p=0.01). Short glass fibre reinforced composite restorations showed an improved marginal integrity when compared to the traditional particulate filler composite restorations.

Longitudinal analysis of progression in glaucoma using spectral-domain optical coherence tomography.

PubMed

Wessel, Julia M; Horn, Folkert K; Tornow, Ralf P; Schmid, Matthias; Mardin, Christian Y; Kruse, Friedrich E; Juenemann, Anselm G; Laemmer, Robert

2013-05-01

To compare the longitudinal loss of RNFL thickness measurements by SD-OCT in healthy individuals and glaucoma patients with or without progression concerning optic disc morphology. A total of 62 eyes, comprising 38 glaucomatous eyes with open angle glaucoma and 24 healthy controls, were included in the study (Erlangen Glaucoma Registry, NTC00494923). All patients were investigated annually over a period of 3 years by Spectralis SD-OCT measuring peripapillary RNFL thickness. By masked comparative analysis of photographs, the eyes were classified into nonprogressive and progressive glaucoma cases. Longitudinal loss of RNFL thickness was compared with morphological changes of optic disc morphology. Mixed model analysis of annual OCT scans revealed an estimated annual decrease of the RNFL thickness by 2.12 μm in glaucoma eyes with progression, whereas glaucoma eyes without progression in optic disc morphology lost 1.18 μm per year in RNFL thickness (P = 0.002). The rate of change in healthy eyes was 0.60 μm and thereby also significantly lower than in glaucoma eyes with progression (P < 0.001). The intrasession variability of three successive measurements without head repositioning was 1.5 ± 0.7 μm. The loss of mean RNFL thickness exceeded the intrasession variability in 60% of nonprogressive eyes, and in 85% of progressive eyes after 3 years. LONGITUDINAL MEASUREMENTS OF RNFL THICKNESS USING SD-OCT SHOW A MORE PRONOUNCED REDUCTION OF RNFL THICKNESS IN PATIENTS WITH PROGRESSION COMPARED WITH PATIENTS WITHOUT PROGRESSION IN GLAUCOMATOUS OPTIC DISC CHANGES. (www.clinicaltrials.gov number, NTC00494923.).

Optic nerve head and fibre layer imaging for diagnosing glaucoma.

PubMed

Michelessi, Manuele; Lucenteforte, Ersilia; Oddone, Francesco; Brazzelli, Miriam; Parravano, Mariacristina; Franchi, Sara; Ng, Sueko M; Virgili, Gianni

2015-11-30

The diagnosis of glaucoma is traditionally based on the finding of optic nerve head (ONH) damage assessed subjectively by ophthalmoscopy or photography or by corresponding damage to the visual field assessed by automated perimetry, or both. Diagnostic assessments are usually required when ophthalmologists or primary eye care professionals find elevated intraocular pressure (IOP) or a suspect appearance of the ONH. Imaging tests such as confocal scanning laser ophthalmoscopy (HRT), optical coherence tomography (OCT) and scanning laser polarimetry (SLP, as used by the GDx instrument), provide an objective measure of the structural changes of retinal nerve fibre layer (RNFL) thickness and ONH parameters occurring in glaucoma. To determine the diagnostic accuracy of HRT, OCT and GDx for diagnosing manifest glaucoma by detecting ONH and RNFL damage. We searched several databases for this review. The most recent searches were on 19 February 2015. We included prospective and retrospective cohort studies and case-control studies that evaluated the accuracy of OCT, HRT or the GDx for diagnosing glaucoma. We excluded population-based screening studies, since we planned to consider studies on self-referred people or participants in whom a risk factor for glaucoma had already been identified in primary care, such as elevated IOP or a family history of glaucoma. We only considered recent commercial versions of the tests: spectral domain OCT, HRT III and GDx VCC or ECC. We adopted standard Cochrane methods. We fitted a hierarchical summary ROC (HSROC) model using the METADAS macro in SAS software. After studies were selected, we decided to use 2 x 2 data at 0.95 specificity or closer in meta-analyses, since this was the most commonly-reported level. We included 106 studies in this review, which analysed 16,260 eyes (8353 cases, 7907 controls) in total. Forty studies (5574 participants) assessed GDx, 18 studies (3550 participants) HRT, and 63 (9390 participants) OCT, with 12 of these studies comparing two or three tests. Regarding study quality, a case-control design in 103 studies raised concerns as it can overestimate accuracy and reduce the applicability of the results to daily practice. Twenty-four studies were sponsored by the manufacturer, and in 15 the potential conflict of interest was unclear.Comparisons made within each test were more reliable than those between tests, as they were mostly based on direct comparisons within each study.The Nerve Fibre Indicator yielded the highest accuracy (estimate, 95% confidence interval (CI)) among GDx parameters (sensitivity: 0.67, 0.55 to 0.77; specificity: 0.94, 0.92 to 0.95). For HRT measures, the Vertical Cup/Disc (C/D) ratio (sensitivity: 0.72, 0.60 to 0.68; specificity: 0.94, 0.92 to 0.95) was no different from other parameters. With OCT, the accuracy of average RNFL retinal thickness was similar to the inferior sector (0.72, 0.65 to 0.77; specificity: 0.93, 0.92 to 0.95) and, in different studies, to the vertical C/D ratio.Comparing the parameters with the highest diagnostic odds ratio (DOR) for each device in a single HSROC model, the performance of GDx, HRT and OCT was remarkably similar. At a sensitivity of 0.70 and a high specificity close to 0.95 as in most of these studies, in 1000 people referred by primary eye care, of whom 200 have manifest glaucoma, such as in those who have already undergone some functional or anatomic testing by optometrists, the best measures of GDx, HRT and OCT would miss about 60 cases out of the 200 patients with glaucoma, and would incorrectly refer 50 out of 800 patients without glaucoma. If prevalence were 5%, e.g. such as in people referred only because of family history of glaucoma, the corresponding figures would be 15 patients missed out of 50 with manifest glaucoma, avoiding referral of about 890 out of 950 non-glaucomatous people.Heterogeneity investigations found that sensitivity estimate was higher for studies with more severe glaucoma, expressed as worse average mean deviation (MD): 0.79 (0.74 to 0.83) for MD < -6 db versus 0.64 (0.60 to 0.69) for MD ≥ -6 db, at a similar summary specificity (0.93, 95% CI 0.92 to 0.94 and, respectively, 0.94; 95% CI 0.93 to 0.95; P < 0.0001 for the difference in relative DOR). The accuracy of imaging tests for detecting manifest glaucoma was variable across studies, but overall similar for different devices. Accuracy may have been overestimated due to the case-control design, which is a serious limitation of the current evidence base.We recommend that further diagnostic accuracy studies are carried out on patients selected consecutively at a defined step of the clinical pathway, providing a description of risk factors leading to referral and bearing in mind the consequences of false positives and false negatives in the setting in which the diagnostic question is made. Future research should report accuracy for each threshold of these continuous measures, or publish raw data.

Structure-Function Relationship between Flicker-Defined Form Perimetry and Spectral-Domain Optical Coherence Tomography in Glaucoma Suspects.

PubMed

Reznicek, Lukas; Muth, Daniel; Vogel, Michaela; Hirneiß, Christoph

2017-03-01

To evaluate the relationship between functional parameters of repeated flicker-defined form perimetry (FDF) and structural parameters of spectral-domain optical coherence tomography (SD-OCT) in glaucoma suspects with normal findings in achromatic standard automated perimetry (SAP). Patients with optic nerve heads (ONH) clinically suspicious for glaucoma and normal SAP findings were enrolled in this prospective study. Each participant underwent visual field (VF) testing with FDF perimetry, using the Heidelberg Edge Perimeter (HEP, Heidelberg Engineering, Heidelberg, Germany) at two consecutive visits. Peripapillary RNFL thickness was obtained by SD-OCT (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Correlations and regression analyses of global and sectoral peripapillary RNFL thickness with corresponding global and regional VF sensitivities were investigated. A consecutive series of 65 study eyes of 36 patients were prospectively included. The second FDF test (HEP II) was used for analysis. Cluster-point based suspicious VF defects were found in 34 eyes (52%). Significant correlations were observed between mean global MD (PSD) of HEP II and SD-OCT-based global peripapillary RNFL thickness (r = 0.380, p = 0.003 for MD and r = -0.516, p < 0.001 for PSD) and RNFL classification scores (R 2 = 0.157, p = 0.002 for MD and R 2 = 0.172, p = 0.001 for PSD). Correlations between mean global MD and PSD of HEP II and sectoral peripapillary RNFL thickness and classification scores showed highest correlations between function and structure for the temporal superior and temporal inferior sectors whereas sectoral MD and PSD correlated weaker with sectoral RNFL thickness. Correlations between linear RNFL values and untransformed logarithmic MD values for each segment were less significant than correlations between logarithmic MD values and RNFL thickness. In glaucoma suspects with normal SAP, global and sectoral peripapillary RNFL thickness is correlated with sensitivity and VF defects in FDF perimetry.

Automated 3D segmentation of intraretinal layers from optic nerve head optical coherence tomography images

NASA Astrophysics Data System (ADS)

Antony, Bhavna J.; Abràmoff, Michael D.; Lee, Kyungmoo; Sonkova, Pavlina; Gupta, Priya; Kwon, Young; Niemeijer, Meindert; Hu, Zhihong; Garvin, Mona K.

2010-03-01

Optical coherence tomography (OCT), being a noninvasive imaging modality, has begun to find vast use in the diagnosis and management of ocular diseases such as glaucoma, where the retinal nerve fiber layer (RNFL) has been known to thin. Furthermore, the recent availability of the considerably larger volumetric data with spectral-domain OCT has increased the need for new processing techniques. In this paper, we present an automated 3-D graph-theoretic approach for the segmentation of 7 surfaces (6 layers) of the retina from 3-D spectral-domain OCT images centered on the optic nerve head (ONH). The multiple surfaces are detected simultaneously through the computation of a minimum-cost closed set in a vertex-weighted graph constructed using edge/regional information, and subject to a priori determined varying surface interaction and smoothness constraints. The method also addresses the challenges posed by presence of the large blood vessels and the optic disc. The algorithm was compared to the average manual tracings of two observers on a total of 15 volumetric scans, and the border positioning error was found to be 7.25 +/- 1.08 μm and 8.94 +/- 3.76 μm for the normal and glaucomatous eyes, respectively. The RNFL thickness was also computed for 26 normal and 70 glaucomatous scans where the glaucomatous eyes showed a significant thinning (p < 0.01, mean thickness 73.7 +/- 32.7 μm in normal eyes versus 60.4 +/- 25.2 μm in glaucomatous eyes).

Characteristics of eyes with inner retinal cleavage.

PubMed

Hwang, Young Hoon; Kim, Yong Yeon; Kim, Hwang Ki; Sohn, Yong Ho

2015-02-01

Inner retinal cleavage can be misdiagnosed as a glaucomatous retinal nerve fiber layer (RNFL) defect. This study was performed to characterize eyes with inner retinal cleavage. Inner retinal cleavage is defined as the appearance of a dark spindle-shaped space between the nerve fibers. Patients who presented at our institution with inner retinal cleavage were enrolled in the study. All participants were evaluated by fundus examination, visual field testing with standard automated perimetry, and optical coherence tomography (OCT) imaging. A total of 15 eyes of 11 subjects with inner retinal cleavage were included in the study. The median age of the subjects was 57 years (age range, 30-67 years). In each case, inner retinal cleavage was located adjacent to retinal blood vessels. Tissue bridging the cleavage area was observed in ten eyes. Six eyes had epiretinal membranes (ERMs), two eyes had glaucoma, and one eye had ERM in addition to glaucoma. Six eyes with inner retinal cleavage without combined ocular abnormalities had highly myopic refractive error (-6.50 to -8.50 diopters). Cross-sectional OCT images of the areas of inner retinal cleavage demonstrated defects with irregular margins and empty spaces in the inner layers of the retina. During the follow-up period, no eye showed changes in inner retinal layer cleavage or visual field sensitivity. Inner retinal cleavage was found in eyes with high myopia or ERMs. Inner retinal cleavage was associated with structural changes distinct from those associated with glaucomatous RNFL defects.

Influence of fibre reinforcement on selected mechanical properties of dental composites.

PubMed

Niewczas, Agata M; Zamościńska, Jolanta; Krzyżak, Aneta; Pieniak, Daniel; Walczak, Agata; Bartnik, Grzegorz

2017-01-01

For splinting or designing adhesive bridges, reconstructive composite structures with increased mechanical properties owing to embedded reinforcement fibres are used. The aim of this article was to determine the influence of glass and aramid fibres on the mechanical strength of composites reinforced with these fibres. Two polymer-ceramic microhybrid materials: Boston and Herculite were tested. Three types of reinforcement fibres were used: aramid (Podwiązka) with a single layer weave, a single layer weave glass fibre (FSO) and triple layer weave glass fibre (FSO evo). Tests were conducted in accordance with the requirements of ISO 4049:2009. The following material types were chosen for research: Boston, Boston + Podwiązka, Herculite, Herculite + Podwiązka, Herculite + FSO and Herculite + FSO evo. The scope of research included: flexural strength B, bending modulus of elasticity εB and work to failure of the reinforced composite Wfb. Additionally, microscopic observations of fracture occurring in samples were made. In comparison: the Herculite (97.7 MPa) type with the Herculite + FSO evo (177.5 MPa) type was characterized by the highest strength. Fibre reinforcement resulted in decreasing the elasticity modulus: Herculite + reinforcement (6.86 GPa; 6.33 GPa; 6.11 GPa) in comparison with the Herculite (9.84 GPa) and respectively Boston + reinforcement (10.08 GPa) as compared with the Boston (11.81 GPa). Using glass fibres increases flexural strength of the test composites. Using aramid fibres does not change their strength. The elasticity modulus of the reinforced reconstructive structures decreases after application of either type of fibres. However, their resistance to the crack initiation increases.

Peripapillary and Macular Vessel Density in Glaucoma Patients with Single-Hemifield Visual Field Defect

PubMed Central

Yarmohammadi, Adeleh; Zangwill, Linda M.; Diniz-Filho, Alberto; Saunders, Luke J.; Suh, Min Hee; Wu, Zhichao; Manalastas, Patricia Isabel C.; Akagi, Tadamichi; Medeiros, Felipe A.; Weinreb, Robert N.

2017-01-01

Purpose To compare hemifield differences in the vessel density of the optic nerve head and macula in open-angle glaucoma (OAG) eyes with visual field (VF) defect confined to one hemifield using optical coherence tomography angiography (OCT-A). Design Cross-sectional study. Participants Fifty-eight eyes of 58 glaucoma patients with VF loss confined to a single hemifield, and 28 healthy eyes. Methods Retinal vasculature information was summarized as circumpapillary vessel density (cpVD) and perifoveal vessel density (pfVD). Circumpapillary retinal nerve fiber layer (cpRNFL) and macular ganglion cell complex (mGCC) thickness were also calculated using spectral domain OCT. Paired and unpaired t-tests were utilized to evaluate differences between the perimetrically affected and intact hemiretinae and healthy hemiretinae. Linear regression analyses were performed to evaluate the associations between VF measures with vascular and structural measurements. Main Outcome Measures Total and hemispheric cpVD, pfVD, cpRNFL, mGCC and mean sensitivity (MS). Results Mean cpVD and pfVD in the intact hemiretinae of OAG eyes (59.0% and 51.1%) were higher than the affected hemiretinae (54.7% and 48.3%; p<0.001) but lower than healthy eyes (62.4% and 53.8%; p<0.001). Similar results were noted with cpRNFL and mGCC thickness measurements (p<0.05 for both). The strongest associations between MS in the affected hemifields were found for cpVD (r = 0.707), followed by pfVD (r = 0.615), cpRNFL (r = 0.496) and mGCC (r = 0.482) in the corresponding hemiretinae (p<0.001 for all). Moreover the correlations in the intact hemifields between MS with cpVD and pfVD were found to be higher (r = 0.450 and 0.403) than the correlations between MS and cpRNFL and mGCC thickness measurements (r = 0.340 and 0.290; all p-values <0.05 for all). Conclusions Reduced peripapillary and macular vessel density was detectable in the perimetrically intact hemiretinae of glaucoma eyes with a single-hemifield defect. Moreover vessel density attenuation in both affected and intact hemiretinae was associated with the extent of VF damage in the corresponding hemifields. OCT-A potentially shows promise for identifying glaucomatous damage before focal VF defects are detectable. PMID:28196732

Scanning laser topography and scanning laser polarimetry: comparing both imaging methods at same distances from the optic nerve head.

PubMed

Kremmer, Stephan; Keienburg, Marcus; Anastassiou, Gerasimos; Schallenberg, Maurice; Steuhl, Klaus-Peter; Selbach, J Michael

2012-01-01

To compare the performance of scanning laser topography (SLT) and scanning laser polarimetry (SLP) on the rim of the optic nerve head and its surrounding area and thereby to evaluate whether these imaging technologies are influenced by other factors beyond the thickness of the retinal nerve fiber layer (RNFL). A total of 154 eyes from 5 different groups were examined: young healthy subjects (YNorm), old healthy subjects (ONorm), patients with normal tension glaucoma (NTG), patients with open-angle glaucoma and early glaucomatous damage (OAGE) and patients with open-angle glaucoma and advanced glaucomatous damage (OAGA). SLT and SLP measurements were taken. Four concentric circles were superimposed on each of the images: the first one measuring at the rim of the optic nerve head (1.0 ONHD), the next measuring at 1.25 optic nerve head diameters (ONHD), at 1.5 ONHD and at 1.75 ONHD. The aligned images were analyzed using GDx/NFA software. Both methods showed peaks of RNFL thickness in the superior and inferior segments of the ONH. The maximum thickness, registered by the SLT device was at the ONH rim where the SLP device tended to measure the lowest values. SLT measurements at the ONH were influenced by other tissues besides the RNFL like blood vessels and glial tissues. SLT and SLP were most strongly correlated at distances of 1.25 and 1.5 ONHD. While both imaging technologies are valuable tools in detecting glaucoma, measurements at the ONH rim should be interpreted critically since both methods might provide misleading results. For the assessment of the retinal nerve fiber layer we would like to recommend for both imaging technologies, SLT and SLP, measurements in 1.25 and 1.5 ONHD distance of the rim of the optic nerve head.

The Influence of Optical Coherence Tomography Measurements of Retinal Nerve Fiber Layer on Decision-Making in Glaucoma Diagnosis.

PubMed

Fu, Lanxing; Aspinall, Peter; Bennett, Gary; Magidson, Jay; Tatham, Andrew J

2017-04-01

To quantify the influence of spectral domain optical coherence tomography (SDOCT) on decision-making in patients with suspected glaucoma. A prospective cross-sectional study involving 40 eyes of 20 patients referred by community optometrists due to suspected glaucoma. All patients had disc photographs and standard automated perimetry (SAP), and results were presented to 13 ophthalmologists who estimated pre-test probability of glaucoma (0-100%) for a total of 520 observations. Ophthalmologists were then permitted to modify probabilities of disease based on SDOCT retinal nerve fiber layer (RNFL) measurements (post-test probability). The effect of information from SDOCT on decision to treat, monitor, or discharge was assessed. Agreement among graders was assessed using intraclass correlation coefficients (ICC) and correlated component regression (CCR) was used to identify variables influencing management decisions. Patients had an average age of 69.0 ± 10.1 years, SAP mean deviation of 2.71 ± 3.13 dB, and RNFL thickness of 86.2 ± 16.7 μm. Average pre-test probability of glaucoma was 37.0 ± 33.6% with SDOCT resulting in a 13.3 ± 18.1% change in estimated probability. Incorporating information from SDOCT improved agreement regarding probability of glaucoma (ICC = 0.50 (95% CI 0.38 to 0.64) without SDOCT versus 0.64 (95% CI 0.52 to 0.76) with SDOCT). SDOCT led to a change from decision to "treat or monitor" to "discharge" in 22 of 520 cases and a change from "discharge" to "treat or monitor" in 11 of 520 cases. Pre-test probability and RNFL thickness were predictors of post-test probability of glaucoma, contributing 69 and 31% of the variance in post-test probability, respectively. Information from SDOCT altered estimated probability of glaucoma and improved agreement among clinicians in those suspected of having the disease.

Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics.

PubMed

Kocaoglu, Omer P; Cense, Barry; Jonnal, Ravi S; Wang, Qiang; Lee, Sangyeol; Gao, Weihua; Miller, Donald T

2011-08-15

Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3×3×3μm(3) resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3°×3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n=5; 29-62years). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were used to assess visibility and size distribution of individual RNFBs. In one subject, we reimaged the same RNFBs twice over a 7month interval and compared bundle width and thickness between the two imaging sessions. Lastly we compared images of an arcuate RNFL defect acquired with UHR-AO-OCT and commercial OCT (Heidelberg Spectralis). Individual RNFBs were distinguishable in all subjects at 3° retinal eccentricity in both cross-sectional and en face views (width: 30-50μm, thickness: 10-15μm). At 6° retinal eccentricity, RNFBs were distinguishable in three of the five subjects in both views (width: 30-45μm, thickness: 20-40μm). Width and thickness RNFB measurements taken 7months apart were strongly correlated (p<0.0005). Mean difference and standard deviation of the differences between the two measurement sessions were -0.1±4.0μm (width) and 0.3±1.5μm (thickness). UHR-AO-OCT outperformed commercial OCT in terms of clarity of the microscopic retina. To our knowledge, these are the first measurements of RNFB cross section reported in the living human eye. Copyright © 2011 Elsevier Ltd. All rights reserved.

Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics

PubMed Central

Kocaoglu, Omer P.; Cense, Barry; Jonnal, Ravi S.; Wang, Qiang; Lee, Sangyeol; Gao, Weihua; Miller, Donald T.

2011-01-01

Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3×3×3 μm3 resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3°×3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n=5; 29–62yrs). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were used to assess visibility and size distribution of individual RNFBs. In one subject, we reimaged the same RNFBs twice over a seven month interval and compared bundle width and thickness between the two imaging sessions. Lastly we compared images of an arcuate RNFL defect acquired with UHR-AO-OCT and commercial OCT (Heidelberg Spectralis). Individual RNFBs were distinguishable in all subjects at 3° retinal eccentricity in both cross-sectional and en face views (width: 30–50μm, thickness: 10–15μm). At 6° retinal eccentricity, RNFBs were distinguishable in three of the five subjects in both views (width: 30–45μm, thickness: 20–40μm). Width and thickness RNFB measurements taken seven months apart were strongly correlated (p<0.0005). Mean difference and standard deviation of the differences between the two measurement sessions were −0.1±4.0 μm (width) and 0.3±1.5 μm (thickness). UHR-AO-OCT outperformed commercial OCT in terms of clarity of the microscopic retina. To our knowledge, these are the first measurements of RNFB cross section reported in the living human eye. PMID:21722662

Radial Peripapillary Capillary Network in Patients with Retinitis Pigmentosa: An Optical Coherence Tomography Angiography Study.

PubMed

Mastropasqua, Rodolfo; Borrelli, Enrico; Agnifili, Luca; Toto, Lisa; Di Antonio, Luca; Senatore, Alfonso; Palmieri, Michele; D'Uffizi, Alessandro; Carpineto, Paolo

2017-01-01

To investigate radial peripapillary capillary (RPC) network in patients affected by retinitis pigmentosa (RP). Eleven patients (22 eyes) with previous diagnosis of RP and 16 age-matched healthy subjects (16 eyes) were enrolled. The diagnosis of RP was made based on both clinical features and electrophysiological examination. All patients underwent a complete ophthalmologic examination, including optical coherence tomography angiography and visual field (VF). The primary outcomes were the RPC vessel density in the peripapillary and disk areas; the secondary outcomes were the peripapillary retinal nerve fiber layer (RNFL) thickness and the mean defect at VF. A total of 19 eyes of 11 RP patients (5 males, 6 females) and 16 eyes of 16 healthy subjects (10 males, 6 females) were included for the analysis. RPC vessel density in the disk area was 46.5 ± 7.1% in the RP group and 45.4 ± 10.6% in the control group ( p  = 0.754). RPC vessel density in the peripapillary area was significantly reduced in the RP group after the comparison with the control group (52.5 ± 5.0 and 57.2 ± 5.1%, respectively, p  = 0.011). RNFL thickness was 85.9 ± 20.4 μm in the RP group and 104.0 ± 6.4 μm in the control group ( p  = 0.002). RPC vessel density was significantly correlated with RNFL thickness values in RP patients, both in the disk and in the peripapillary area (Rho = 0.599 and p  = 0.007 in the disk area, Rho = 0.665 and p  = 0.002 in the peripapillary area, respectively). We showed that density of RPC is reduced in these patients in the peripapillary area. Moreover, the RPC vessel density correlates with the RNFL thickness.

Diagnosis of glaucoma and detection of glaucoma progression using spectral domain optical coherence tomography.

PubMed

Grewal, Dilraj S; Tanna, Angelo P

2013-03-01

With the rapid adoption of spectral domain optical coherence tomography (SDOCT) in clinical practice and the recent advances in software technology, there is a need for a review of the literature on glaucoma detection and progression analysis algorithms designed for the commercially available instruments. Peripapillary retinal nerve fiber layer (RNFL) thickness and macular thickness, including segmental macular thickness calculation algorithms, have been demonstrated to be repeatable and reproducible, and have a high degree of diagnostic sensitivity and specificity in discriminating between healthy and glaucomatous eyes across the glaucoma continuum. Newer software capabilities such as glaucoma progression detection algorithms provide an objective analysis of longitudinally obtained structural data that enhances our ability to detect glaucomatous progression. RNFL measurements obtained with SDOCT appear more sensitive than time domain OCT (TDOCT) for glaucoma progression detection; however, agreement with the assessments of visual field progression is poor. Over the last few years, several studies have been performed to assess the diagnostic performance of SDOCT structural imaging and its validity in assessing glaucoma progression. Most evidence suggests that SDOCT performs similarly to TDOCT for glaucoma diagnosis; however, SDOCT may be superior for the detection of early stage disease. With respect to progression detection, SDOCT represents an important technological advance because of its improved resolution and repeatability. Advancements in RNFL thickness quantification, segmental macular thickness calculation and progression detection algorithms, when used correctly, may help to improve our ability to diagnose and manage glaucoma.

Glaucoma Structural and Functional Progression in American and Korean Cohorts

PubMed Central

Kostanyan, Tigran; Sung, Kyung Rim; Schuman, Joel S.; Ling, Yun; Lucy, Katie A.; Bilonick, Richard A.; Ishikawa, Hiroshi; Kagemann, Larry; Lee, Jin Y.; Wollstein, Gadi

2016-01-01

Objective To compare the rate of glaucoma structural and functional progression in American and Korean cohorts. Design Retrospective longitudinal study. Participants 313 eyes from 189 glaucoma and glaucoma suspects, followed for an average of 38 months. Methods All subjects were examined semiannually with visual field (VF) testing and spectral-domain optical coherence tomography. All subjects had ≥5 reliable visits. Main Outcome Measurements The rates of change of retinal nerve fiber layer (RNFL) thickness, cup-to-disc (C/D) ratios, and VF mean deviation (MD) were compared between the cohorts. Variables affecting the rate of change for each parameter were determined, including ethnicity, refraction, baseline age and severity, disease subtype (high vs. normal tension glaucoma), clinical diagnosis (glaucoma vs. glaucoma suspect), and the interactions between variables. Results The Korean cohort was predominantly normal tension glaucoma, while the American cohort was high tension glaucoma. Cohorts had similar VF parameters at baseline, but the Korean eyes had significantly thinner mean RNFL and larger cups. Korean glaucoma eyes showed a faster thinning of mean RNFL (mean: −0.71 vs. −0.24μm/year, p<0.01). There was no detectable difference in the rate of change between the glaucoma cohorts for C/D ratios and VF MD and for all parameters in glaucoma suspect eyes. Different combinations of the tested variables significantly impacted the rate of change. Conclusion Ethnicity, baseline severity, disease subtype, and clinical diagnosis should be considered when comparing glaucoma progression studies. PMID:26778345

Retinal architecture and mfERG: Optic nerve head component response characteristics in MS.

PubMed

Schnurman, Zane S; Frohman, Teresa C; Beh, Shin C; Conger, Darrel; Conger, Amy; Saidha, Shiv; Galetta, Steven; Calabresi, Peter A; Green, Ari J; Balcer, Laura J; Frohman, Elliot M

2014-05-27

To describe a novel neurophysiologic signature of the retinal ganglion cell and to elucidate its relationship to abnormalities in validated structural and functional measures of the visual system. We used multifocal electroretinogram-generated optic nerve head component (ONHC) responses from normal subjects (n = 18), patients with multiple sclerosis (MS) (n = 18), and those with glaucoma (n = 3). We then characterized the relationship between ONHC response abnormalities and performance on low-contrast visual acuity, multifocal visual-evoked potential-induced cortical responses, and average and quadrant retinal nerve fiber layer (RNFL) thicknesses, as measured by spectral-domain optical coherence tomography. Compared with the eyes of normal subjects, the eyes of patients with MS exhibited an increased number of abnormal or absent ONHC responses (p < 0.0001). For every 7-letter reduction in low-contrast letter acuity, there were corresponding 4.6 abnormal ONHC responses at 2.5% contrast (p < 0.0001) and 6.6 abnormalities at the 1.25% contrast level (p < 0.0001). Regarding average RNFL thickness, for each 10-μm thickness reduction, we correspondingly observed 6.8 abnormal ONHC responses (p = 0.0002). The most robust association was between RNFL thinning in the temporal quadrant and ONHC response abnormalities (p < 0.0001). Further characterization of ONHC abnormalities (those that are reversible and irreversible) may contribute to the development of novel neurotherapeutic strategies aimed at achieving neuroprotective, and perhaps even neurorestorative, effects in disorders that target the CNS in general, and MS in particular. © 2014 American Academy of Neurology.

Ocular changes in primary hypothyroidism

PubMed Central

2009-01-01

Background To determine the ocular changes related to hypothyrodism in newly diagnosed patients without orbitopathy. Findings Thirty-three patients diagnosed to have primary overt hypothyroidism were enrolled in the study. All subjects were assigned to underwent central corneal thickness (CCT), anterior chamber volume, depth and angle measurements with the Scheimpflug camera (Pentacam, Oculus) and cup to disc ratio (C/D), mean retinal thickness and mean retinal nerve fiber layer (RNFL) thickness measurements with optical coherence tomography (OCT) in addition to ophthalmological examination preceeding the replacement therapy and at the 1st, 3rd and 6th months of treatment. The mean age of the patients included in the study were 40.58 ± 1.32 years. The thyroid hormone levels return to normal levels in all patients during the follow-up period, however the mean intraocular pressure (IOP) revealed no significant change. The mean CCT was 538.05 ± 3.85 μ initially and demonstrated no statistically significant change as the anterior chamber volume, depth and angle measurements did. The mean C/D ratio was 0.29 ± 0.03 and the mean retinal thickness was 255.83 ± 19.49 μ initially and the treatment did not give rise to any significant change. The mean RNFL thickness was also stable during the control visits, so no statistically significant change was encountered. Conclusions Neither hypothyroidism, nor its replacement therapy gave rise to any change of IOP, CCT, anterior chamber parameters, RNFL, retinal thickness and C/D ratio. PMID:20040111

Correlation between CHA2DS2-VASc Score and Glaucoma Treatment and Prognosis.

PubMed

Pikkel, Yoav Y; Krebs, Daniel; Igal, Vadim; Sharabi-Nov, Adi; Epstein, Irena; Pikkel, Joseph

2018-01-01

To find if CHA 2 DS 2 -VASc scale can accurately predict the treatment, prognosis, and outcome for primary open-angle glaucoma (POAG). A survey of 250,000 patient years was taken, using the records of the Ophthalmology Department at Ziv Medical Center. Data was collected regarding the retinal nerve fiber layer (RNFL), visual field (VF), line of treatment (LOT) of glaucoma, and all the data needed to accurately calculate CHA 2 DS 2 -VASc score for each patient. Sixty-seven patients were included in the statistical analysis. The mean age was 72.5 years. The mean CHA 2 DS 2 -VASc score was 3.27 + -1.7. Positive Pearson's correlation coefficients were found for LOT and CHA 2 DS 2 -VASc score, 0.35, and for RNFL grade and CHA2DS2-VASc score, 0.37. The correlation was negative for RNFL width and CHA2DS2-VASc score, -0.35. CHA 2 DS 2 -VASc score was shown to be correlated with glaucoma. This correlation was manifested positively by the LOT needed to stop glaucoma progression, with higher CHA 2 DS 2 -VASc scores correlated with more aggressive treatment. Since glaucoma is a disease with a progressing nature, it is important to treat patients aggressively on one hand, while offering the most benign treatment as possible on the other hand. Modification of the CHA 2 DS 2 -VASc score could achieve an even higher correlation.

What Happens during Natural Protein Fibre Dissolution in Ionic Liquids.

PubMed

Chen, Jingyu; Vongsanga, Kylie; Wang, Xungai; Byrne, Nolene

2014-08-28

Here, we monitor the dissolution of several natural protein fibres such as wool, human hair and silk, in various ionic liquids (ILs). The dissolution of protein-based materials using ILs is an emerging area exploring the production of new materials from waste products. Wool is a keratin fibre, which is extensively used in the textiles industry and as a result has considerable amounts of waste produced each year. Wool, along with human hair, has a unique morphology whereby the outer layer, the cuticle, is heavily cross linked with disulphide bonds, whereas silk does not have this outer layer. Here we show how ILs dissolve natural protein fibres and how the mechanism of dissolution is directly related to the structure and morphology of the wool fibre.

A target fibre study on seats in public houses.

PubMed

Kelly, E; Griffin, R M

1998-01-01

A target fibre survey was conducted to assess the random occurrence of a blue wool fibre on seats in public houses throughout the United Kingdom. Fibre tape lifts were taken from 80 seats. Four seats yielded matching fibres and five of these were found on one seat. A total of 292 fibres were identified; nine fibres proved indistinguishable from the target after comparison microscopy, microspectro-photometry and attempts at thin layer chromatography, and two of these fibres were still apparently indistinguishable after TLC analysis although only one dye component was visible.

Collagen fibre characterisation in arterial tissue under load using SALS.

PubMed

Gaul, R T; Nolan, D R; Lally, C

2017-11-01

The collagen fibre architecture of arterial tissue is known to play a key role in its resultant mechanical behaviour, while maladaptive remodelling of this architecture may be linked to disease. Many of the techniques currently used to analyse collagen fibre architecture require time consuming tissue preparation procedures and are destructive in nature. The aim of this study is to fully explore Small Angle Light Scattering (SALS) as a means to non-destructively assess collagen fibre architecture in arterial tissue and subsequently gain insights into load induced reorientation. The optimised configuration of the SALS system for arterial tissue was determined using quantitative comparisons to histological analyses of porcine carotid artery as its basis. Once established, layer specific fibre orientation and the influence of tissue loading was determined for thin sections of carotid artery using SALS. This process was subsequently repeated for intact carotid artery layers. A single family of circumferentially orientated collagen fibres were found in the intima (- 0.1 ± 1.4° (5.5°)) and media (- 1.7 ± 1.9° (4.7°)) while two perpendicular families of fibres were identified in the adventitia (- 6.4 ± 0.7° (37.7°)) and (118.3 ± 2.7 (39.9°)). An increase in fibre alignment in response to a 20% circumferential strain was also identified using SALS, characterised by an increase in scattered light eccentricity. determined using SALS agreed with those found using traditional destructive techniques, however SALS has the important benefits of allowing vessel layers to remain intact, and has a fast processing time. SALS unique ability to identify load induced reorganisation in intact arterial layers offers an efficient means to gain crucial insights into arterial disease and its development over time. Copyright © 2017 Elsevier Ltd. All rights reserved.

OPTICAL FIBRES AND FIBREOPTIC SENSORS: Bismuth-ring-doped fibres

NASA Astrophysics Data System (ADS)

Zlenko, Aleksandr S.; Akhmetshin, Ural G.; Dvoirin, Vladislav V.; Bogatyrev, Vladimir A.; Firstov, Sergei V.

2009-11-01

A new process for bismuth doping of optical fibres is proposed in which the dopant is introduced into a thin layer surrounding the fibre core. This enables bismuth stabilisation in the silica glass, with no limitations on the core composition. In particular, the GeO2 content of the fibre core in this study is 16 mol %. Spectroscopic characterisation of such fibres and optical gain measurements suggest that the proposed approach has considerable potential for laser applications.

What Happens during Natural Protein Fibre Dissolution in Ionic Liquids

PubMed Central

Chen, Jingyu; Vongsanga, Kylie; Wang, Xungai; Byrne, Nolene

2014-01-01

Here, we monitor the dissolution of several natural protein fibres such as wool, human hair and silk, in various ionic liquids (ILs). The dissolution of protein-based materials using ILs is an emerging area exploring the production of new materials from waste products. Wool is a keratin fibre, which is extensively used in the textiles industry and as a result has considerable amounts of waste produced each year. Wool, along with human hair, has a unique morphology whereby the outer layer, the cuticle, is heavily cross linked with disulphide bonds, whereas silk does not have this outer layer. Here we show how ILs dissolve natural protein fibres and how the mechanism of dissolution is directly related to the structure and morphology of the wool fibre. PMID:28788183

Analysis of macular and nerve fiber layer thickness in multiple sclerosis patients according to severity level and optic neuritis episodes.

PubMed

Soler García, A; Padilla Parrado, F; Figueroa-Ortiz, L C; González Gómez, A; García-Ben, A; García-Ben, E; García-Campos, J M

2016-01-01

Quantitative assessment of macular and nerve fibre layer thickness in multiple sclerosis patients with regard to expanded disability status scale (EDSS) and presence or absence of previous optic neuritis episodes. We recruited 62 patients with multiple sclerosis (53 relapsing-remitting and 9 secondary progressive) and 12 disease-free controls. All patients underwent an ophthalmological examination, including quantitative analysis of the nerve fibre layer and macular thickness using optical coherence tomography. Patients were classified according to EDSS as A (lower than 1.5), B (between 1.5 and 3.5), and C (above 3.5). Mean nerve fibre layer thickness in control, A, B, and C groups was 103.35±12.62, 99.04±14.35, 93.59±15.41, and 87.36±18.75μm respectively, with statistically significant differences (P<.05). In patients with no history of optic neuritis, history of episodes in the last 3 to 6 months, or history longer than 6 months, mean nerve fibre layer thickness was 99.25±13.71, 93.92±13.30 and 80.07±15.91μm respectively; differences were significant (P<.05). Mean macular thickness in control, A, B, and C groups was 220.01±12.07, 217.78±20.02, 217.68±20.77, and 219.04±24.26μm respectively. Differences were not statistically significant. The mean retinal nerve fibre layer thickness in multiple sclerosis patients is related to the EDSS level. Patients with previous optic neuritis episodes have a thinner retinal nerve fibre layer than patients with no history of these episodes. Mean macular thickness is not correlated to EDSS level. Copyright © 2014 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

Repeatability and Reproducibility of Retinal Nerve Fiber Layer Parameters Measured by Scanning Laser Polarimetry with Enhanced Corneal Compensation in Normal and Glaucomatous Eyes.

PubMed

Ara, Mirian; Ferreras, Antonio; Pajarin, Ana B; Calvo, Pilar; Figus, Michele; Frezzotti, Paolo

2015-01-01

To assess the intrasession repeatability and intersession reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness parameters measured by scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) in healthy and glaucomatous eyes. One randomly selected eye of 82 healthy individuals and 60 glaucoma subjects was evaluated. Three scans were acquired during the first visit to evaluate intravisit repeatability. A different operator obtained two additional scans within 2 months after the first session to determine intervisit reproducibility. The intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) were calculated for all SLP parameters in both groups. ICCs ranged from 0.920 to 0.982 for intravisit measurements and from 0.910 to 0.978 for intervisit measurements. The temporal-superior-nasal-inferior-temporal (TSNIT) average was the highest (0.967 and 0.946) in normal eyes, while nerve fiber indicator (NFI; 0.982) and inferior average (0.978) yielded the best ICC in glaucomatous eyes for intravisit and intervisit measurements, respectively. All COVs were under 10% in both groups, except NFI. TSNIT average had the lowest COV (2.43%) in either type of measurement. Intervisit TRT ranged from 6.48 to 12.84. The reproducibility of peripapillary RNFL measurements obtained with SLP-ECC was excellent, indicating that SLP-ECC is sufficiently accurate for monitoring glaucoma progression.

Sensitivity of visual evoked potentials and spectral domain optical coherence tomography in early relapsing remitting multiple sclerosis.

PubMed

Behbehani, Raed; Ahmed, Samar; Al-Hashel, Jasem; Rousseff, Rossen T; Alroughani, Raed

2017-02-01

Visual evoked potentials and spectral-domain optical coherence tomography are common ancillary studies that assess the visual pathways from a functional and structural aspect, respectively. To compare prevalence of abnormalities of Visual evoked potentials (VEP) and spectral-domain optical coherence tomography (SDOCT) in patients with relapsing remitting multiple sclerosis (RRMS). A cross-sectional study of 100 eyes with disease duration of less than 5 years since the diagnosis. Correlation between retinal nerve fiber layer and ganglion-cell/inner plexiform layer with pattern-reversal visual evoked potentials amplitude and latency and contrast sensitivity was performed. The prevalence of abnormalities in pattern-reversal visual VEP was 56% while that of SOCT was 48% in all eyes. There was significant negative correlations between the average RNFL (r=-0.34, p=0.001) and GCIPL (r=-0.39, p<0.001) with VEP latency. In eyes with prior optic neuritis, a significant negative correlation was seen between average RNFL (r=-0.33, p=0.037) and GCIPL (r=-0.40, p=0.010) with VEP latency. We have found higher prevalence of VEP abnormalities than SCOCT in early relapsing-remitting multiple sclerosis. This suggests that VEP has a higher sensitivity for detecting lesions of the visual pathway in patients with early RRMS. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface electrical properties of stainless steel fibres: An AFM-based study

NASA Astrophysics Data System (ADS)

Yin, Jun; D'Haese, Cécile; Nysten, Bernard

2015-03-01

Atomic force microscopy (AFM) electrical modes were used to study the surface electrical properties of stainless steel fibres. The surface electrical conductivity was studied by current sensing AFM and I-V spectroscopy. Kelvin probe force microscopy was used to measure the surface contact potential. The oxide film, known as passivation layer, covering the fibre surface gives rise to the observation of an apparently semiconducting behaviour. The passivation layer generally exhibits a p-type semiconducting behaviour, which is attributed to the predominant formation of chromium oxide on the surface of the stainless steel fibres. At the nanoscale, different behaviours are observed from points to points, which may be attributed to local variations of the chemical composition and/or thickness of the passivation layer. I-V curves are well fitted with an electron tunnelling model, indicating that electron tunnelling may be the predominant mechanism for electron transport.

Histogram Matching Extends Acceptable Signal Strength Range on Optical Coherence Tomography Images

PubMed Central

Chen, Chieh-Li; Ishikawa, Hiroshi; Wollstein, Gadi; Bilonick, Richard A.; Sigal, Ian A.; Kagemann, Larry; Schuman, Joel S.

2015-01-01

Purpose. We minimized the influence of image quality variability, as measured by signal strength (SS), on optical coherence tomography (OCT) thickness measurements using the histogram matching (HM) method. Methods. We scanned 12 eyes from 12 healthy subjects with the Cirrus HD-OCT device to obtain a series of OCT images with a wide range of SS (maximal range, 1–10) at the same visit. For each eye, the histogram of an image with the highest SS (best image quality) was set as the reference. We applied HM to the images with lower SS by shaping the input histogram into the reference histogram. Retinal nerve fiber layer (RNFL) thickness was automatically measured before and after HM processing (defined as original and HM measurements), and compared to the device output (device measurements). Nonlinear mixed effects models were used to analyze the relationship between RNFL thickness and SS. In addition, the lowest tolerable SSs, which gave the RNFL thickness within the variability margin of manufacturer recommended SS range (6–10), were determined for device, original, and HM measurements. Results. The HM measurements showed less variability across a wide range of image quality than the original and device measurements (slope = 1.17 vs. 4.89 and 1.72 μm/SS, respectively). The lowest tolerable SS was successfully reduced to 4.5 after HM processing. Conclusions. The HM method successfully extended the acceptable SS range on OCT images. This would qualify more OCT images with low SS for clinical assessment, broadening the OCT application to a wider range of subjects. PMID:26066749

Protective effect of high concentration of BN52021 on retinal contusion in cat eyes.

PubMed

Huang, Jin-Feng; Zhao, Hai-Peng; Yang, Yan-Feng; Huang, Hui-Min; Yao, Yi; Wang, Zhi-Jun

2015-05-09

Blunt injuries/contusion on eyes might cause retina blunt trauma. This study is to evaluate the protective function of BN52021 against retinal trauma. A total of 70 cats, 6 months old, were divided into six groups: Group A to E (n = 12) and normal control (N) group (n = 10). The right eyes in Group A to E were contused. All experiments were performed under general anesthetization. Retrobulbar injections of medication in right eyes were performed. Cats were administrated with 0.5 mL of normal saline (NS), dimethyl sulphoxide, 0.2 g/L BN52021, 1 g/L BN52021 and 5 g/L BN52021, respectively. Cats in Group N were administrated with 0.5 mL of NS. Intraocular pressure (IOP), flash electroretinogram (ERG), and retinal nerve fiber layer (RNFL) thickness were measured. Hematoxylin and eosin (HE) staining and transmission electron microscope (TEM) were detected. No significant difference was observed in IOP levels among groups. Comparing with cats in Group N, those in Group A to E showed significant lower amplitudes of rod a- and b-waves (P < 0.05). Amplitudes of rod a- and b-waves were increased by administration of high concentration of BN52021 (≥ 1 g/L). Moreover, high concentration of BN52021 decreased the RNFL thickness increased by contusion. Axons in RNFL in Group E arranged neatly at 7 days after modeling. The degenerated axons caused by contusion were repaired by BN52021. The administration of high concentration of (≥ 1 g/L) BN52021 could partially repair retinal function in contused cat eyes.

Longitudinal Detection of Optic Nerve Head Changes by Spectral Domain Optical Coherence Tomography in Early Experimental Glaucoma

PubMed Central

He, Lin; Yang, Hongli; Gardiner, Stuart K.; Williams, Galen; Hardin, Christy; Strouthidis, Nicholas G.; Fortune, Brad; Burgoyne, Claude F.

2014-01-01

Purpose. We determined if the detection of spectral-domain optical coherence tomography (SDOCT) optic nerve head (ONH) change precedes the detection of confocal scanning laser tomography (CSLT) ONH surface, SDOCT retinal nerve fiber layer (RNFL), scanning laser perimetry (SLP), and multifocal electroretinography (mfERG) change in eight experimental glaucoma (EG) eyes. Methods. Both eyes from eight monkeys were tested at least three times at baseline, and then every 2 weeks following laser-induced chronic unilateral IOP elevation. Event and trend-based definitions of onset in the control and EG eyes for 11 SDOCT neural and connective tissue, CSLT surface, SDOCT RNFL, SLP, and mfERG parameters were explored. The frequency and timing of onset for each parameter were compared using a logrank test. Results. Maximum post-laser IOP was 18 to 42 mm Hg in the EG eyes and 12 to 20 mm Hg in the control eyes. For event- and trend-based analyses, onsets were achieved earliest and most frequently within the ONH neural and connective tissues using SDOCT, and at the ONH surface using CSLT. SDOCT ONH neural and connective tissue parameter change preceded or coincided with CSLT ONH surface change in most EG eyes. The SDOCT and SLP measures of RNFL thickness, and mfERG measures of visual function demonstrated similar onset rates, but occurred later than SDOCT ONH and CSLT surface change, and in fewer eyes. Conclusions. SDOCT ONH change detection commonly precedes or coincides with CSLT ONH surface change detection, and consistently precedes RNFLT, SLP, and mfERG change detection in monkey experimental glaucoma. PMID:24255047

Effect of surface modification of nanofibres with glutamic acid peptide on calcium phosphate nucleation and osteogenic differentiation of marrow stromal cells.

PubMed

Karaman, Ozan; Kumar, Ankur; Moeinzadeh, Seyedsina; He, Xuezhong; Cui, Tong; Jabbari, Esmaiel

2016-02-01

Biomineralization is mediated by extracellular matrix (ECM) proteins with amino acid sequences rich in glutamic acid. The objective of this study was to investigate the effect of calcium phosphate deposition on aligned nanofibres surface-modified with a glutamic acid peptide on osteogenic differentiation of rat marrow stromal cells. Blend of EEGGC peptide (GLU) conjugated low molecular weight polylactide (PLA) and high molecular weight poly(lactide-co-glycolide) (PLGA) was electrospun to form aligned nanofibres (GLU-NF). The GLU-NF microsheets were incubated in a modified simulated body fluid for nucleation of calcium phosphate crystals on the fibre surface. To achieve a high calcium phosphate to fibre ratio, a layer-by-layer approach was used to improve diffusion of calcium and phosphate ions inside the microsheets. Based on dissipative particle dynamics simulation of PLGA/PLA-GLU fibres, > 80% of GLU peptide was localized to the fibre surface. Calcium phosphate to fibre ratios as high as 200%, between those of cancellous (160%) and cortical (310%) bone, was obtained with the layer-by-layer approach. The extent of osteogenic differentiation and mineralization of marrow stromal cells seeded on GLU-NF microsheets was directly related to the amount of calcium phosphate deposition on the fibres prior to cell seeding. Expression of osteogenic markers osteopontin, alkaline phosphatase (ALP), osteocalcin and type 1 collagen increased gradually with calcium phosphate deposition on GLU-NF microsheets. Results demonstrate that surface modification of aligned synthetic nanofibres with EEGGC peptide dramatically affects nucleation and growth of calcium phosphate crystals on the fibres leading to increased osteogenic differentiation of marrow stromal cells and mineralization. Copyright © 2013 John Wiley & Sons, Ltd.

Stress strain modelling and analysis of a piezo-coated optical fibre sensor

NASA Astrophysics Data System (ADS)

Al-Raweshidy, H.; Ali, H.; Obayya, S. S. A.; Langley, R.; Batchelor, J.

2005-02-01

A finite element model, using commercially available software, is presented to simulate the piezoelectrically induced stresses and strains in an optical fibre to be used as antenna. These stresses and strains are generated by a layer of piezoelectric polymer deposited on the cladding of a short fibre sample. The theoretical basis for the work is briefly explained and the modelling process is emphasised. Two types of fibre are investigated - circular fibre and D-fibre, and the results compared, analysed and discussed. It is shown that in the D-fibre, the stress and displacement increased by 1.46 and 115 times, respectively, in comparison with the circular fibre.

Visual Structure and Function in Collision Sport Athletes.

PubMed

Leong, Danielle; Morettin, Christina; Messner, Leonard V; Steinmetz, Robert J; Pang, Yi; Galetta, Steven L; Balcer, Laura J

2017-09-06

Vision-based measures have been shown to be useful markers in multiple sclerosis (MS), Alzheimer and Parkinson disease. Therefore, these testing paradigms may have applications to populations explaining repetitive head trauma that has been associated with long-term neurodegenerative sequelae. We investigated retinal structure and visual function in professional collision sport athletes compared to age- and race-matched control participants. In this cross-sectional study, participants underwent spectral-domain optical coherence tomography (OCT) measurements of peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC = ganglion cell + inner plexiform layers) thickness. High-contrast visual acuity (100% level), low-contrast letter acuity (LCLA) (1.25% and 2.5% levels), and King-Devick Test of rapid number naming performance were administered. Vision-specific quality of life (QOL) measures were assessed. Among 46 collision sport athletes (boxing, n = 14; football, n = 29; ice hockey, n = 3) and 104 control participants, average RNFL thickness was a significant predictor of athlete vs control status with athletes demonstrating 4.8-μm of thinning compared to controls (P = 0.01, generalized estimating equation [GEE] models accounting for age and within-subject, intereye correlations). Athlete vs control status was not a predictor of RNFL thickness for the subgroup of football players in this cohort (P = 0.60). Binocular (P = 0.001) and monocular (P = 0.02) LCLA at 2.5% contrast and vision-specific QOL (P = 0.04) were significant predictors of athlete vs control status (GEE models accounting for age and within-subject, intereye correlations). Rapid number naming performance times were not significantly different between the control and athlete groups. This study showed that retinal axonal and neuronal loss is present among collision sport athletes, with most notable differences seen in boxers. These findings are accompanied by reductions in visual function and QOL, similar to patterns observed in multiple sclerosis, Alzheimer and Parkinson diseases. Vision-based changes associated with head trauma exposure that have the potential to be detected in vivo represent a unique opportunity for further study to determine if these changes in collision sport athletes are predictive of future neurodegeneration.

Validation of the UNC OCT Index for the Diagnosis of Early Glaucoma

PubMed Central

Lee, Gary; Budenz, Donald L.; Warren, Joshua L.; Wall, Michael; Artes, Paul H.; Callan, Thomas M.; Flanagan, John G.

2018-01-01

Purpose To independently validate the performance of the University of North Carolina Optical Coherence Tomography (UNC OCT) Index in diagnosing and predicting early glaucoma. Methods Data of 118 normal subjects (118 eyes) and 96 subjects (96 eyes) with early glaucoma defined as visual field mean deviation (MD) greater than −4 decibels (dB), aged 40 to 80 years, and who were enrolled in the Full-Threshold Testing Size III, V, VI comparison study were used in this study. CIRRUS OCT average and quadrants' retinal nerve fiber layer (RNFL); optic disc vertical cup-to-disc ratio (VCDR), cup-to-disc area ratio, and rim area; and average, minimum, and six sectoral ganglion cell-inner plexiform layer (GCIPL) measurements were run through the UNC OCT Index algorithm. Area under the receiver operating characteristic curve (AUC) and sensitivities at 95% and 99% specificity were calculated and compared between single parameters and the UNC OCT Index. Results Mean age was 60.1 ± 11.0 years for normal subjects and 66.5 ± 8.1 years for glaucoma patients (P < 0.001). MD was 0.29 ± 1.04 dB and −1.30 ± 1.35 dB in normal and glaucomatous eyes (P < 0.001), respectively. The AUC of the UNC OCT Index was 0.96. The best single metrics when compared to the UNC OCT Index were VCDR (0.93, P = 0.054), average RNFL (0.92, P = 0.014), and minimum GCIPL (0.91, P = 0.009). The sensitivities at 95% and 99% specificity were 85.4% and 76.0% (UNC OCT Index), 71.9% and 62.5% (VCDR, all P < 0.001), 64.6% and 53.1% (average RNFL, all P < 0.001), and 66.7% and 58.3% (minimum GCIPL, all P < 0.001), respectively. Conclusions The findings confirm that the UNC OCT Index may provide improved diagnostic perforce over that of single OCT parameters and may be a good tool for detection of early glaucoma. Translational Relevance The UNC OCT Index algorithm may be incorporated easily into routine clinical practice and be useful for detecting early glaucoma. PMID:29629238

Validation of the UNC OCT Index for the Diagnosis of Early Glaucoma.

PubMed

Mwanza, Jean-Claude; Lee, Gary; Budenz, Donald L; Warren, Joshua L; Wall, Michael; Artes, Paul H; Callan, Thomas M; Flanagan, John G

2018-04-01

To independently validate the performance of the University of North Carolina Optical Coherence Tomography (UNC OCT) Index in diagnosing and predicting early glaucoma. Data of 118 normal subjects (118 eyes) and 96 subjects (96 eyes) with early glaucoma defined as visual field mean deviation (MD) greater than -4 decibels (dB), aged 40 to 80 years, and who were enrolled in the Full-Threshold Testing Size III, V, VI comparison study were used in this study. CIRRUS OCT average and quadrants' retinal nerve fiber layer (RNFL); optic disc vertical cup-to-disc ratio (VCDR), cup-to-disc area ratio, and rim area; and average, minimum, and six sectoral ganglion cell-inner plexiform layer (GCIPL) measurements were run through the UNC OCT Index algorithm. Area under the receiver operating characteristic curve (AUC) and sensitivities at 95% and 99% specificity were calculated and compared between single parameters and the UNC OCT Index. Mean age was 60.1 ± 11.0 years for normal subjects and 66.5 ± 8.1 years for glaucoma patients ( P < 0.001). MD was 0.29 ± 1.04 dB and -1.30 ± 1.35 dB in normal and glaucomatous eyes ( P < 0.001), respectively. The AUC of the UNC OCT Index was 0.96. The best single metrics when compared to the UNC OCT Index were VCDR (0.93, P = 0.054), average RNFL (0.92, P = 0.014), and minimum GCIPL (0.91, P = 0.009). The sensitivities at 95% and 99% specificity were 85.4% and 76.0% (UNC OCT Index), 71.9% and 62.5% (VCDR, all P < 0.001), 64.6% and 53.1% (average RNFL, all P < 0.001), and 66.7% and 58.3% (minimum GCIPL, all P < 0.001), respectively. The findings confirm that the UNC OCT Index may provide improved diagnostic perforce over that of single OCT parameters and may be a good tool for detection of early glaucoma. The UNC OCT Index algorithm may be incorporated easily into routine clinical practice and be useful for detecting early glaucoma.

The effects of stacking sequence and thermal cycling on the flexural properties of laminate composites of aluminium-epoxy/basalt-glass fibres

NASA Astrophysics Data System (ADS)

Abdollahi Azghan, Mehdi; Eslami-Farsani, Reza

2018-02-01

The current study aimed at investigating the effects of different stacking sequences and thermal cycling on the flexural properties of fibre metal laminates (FMLs). FMLs were composed of two aluminium alloy 2024-T3 sheets and epoxy polymer-matrix composites that have four layers of basalt and/or glass fibres with five different stacking sequences. For FML samples the thermal cycle time was about 6 min for temperature cycles from 25 °C to 115 °C. Flexural properties of samples evaluated after 55 thermal cycles and compared to non-exposed samples. Surface modification of aluminium performed by electrochemical treatment (anodizing) method and aluminium surfaces have been examined by scanning electron microscopy (SEM). Also, the flexural failure mechanisms investigated by the optical microscope study of fractured surfaces. SEM images indicated that the porosity of the aluminium surface increased after anodizing process. The findings of the present study showed that flexural modulus were maximum for basalt fibres based FML, minimum for glass fibres based FML while basalt/glass fibres based FML lies between them. Due to change in the failure mechanism of basalt/glass fibres based FMLs that have glass fibres at outer layer of the polymer composite, the flexural strength of this FML is lower than glass and basalt fibres based FML. After thermal cycling, due to the good thermal properties of basalt fibres, flexural properties of basalt fibres based FML structures decreased less than other composites.

SpaceFibre: The Standard and the Multi-Lane Layer

NASA Astrophysics Data System (ADS)

Parkes, Steve; McClements, Chris; McLaren, David; Florit, Albert Ferrer; Gonzalez Villafranca, Alberto

2016-08-01

SpaceFibre is a new standard for spacecraft on-board data-handling networks, initially designed to deliver multi-Gbit/s data rates for synthetic aperture radar and high-resolution, multi-spectral imaging instruments, The addition of quality of service (QoS) and fault detection, isolation and recovery (FDIR) capabilities to SpaceFibre has resulted in a unified network technology. SpaceFibre provides high bandwidth, low latency, fault isolation and recovery suitable for space applications, and novel QoS that combines priority, bandwidth reservation and scheduling and which provides babbling node protection. SpaceFibre is backwards compatible with the widely used SpaceWire standard at the network level allowing simple interconnection of existing SpaceWire equipment to a SpaceFibre link or network.Developed by STAR-Dundee and the University of Dundee for the European Space Agency (ESA) SpaceFibre is able to operate over fibre-optic and electrical cable. A single lane of SpaceFibre comprises four signals (TX+/- and RX+/-) and supports data rates of 2 Gbits/s (2.5 Gbits/s data signalling rate) with data rates up to 5 Gbits/s already planned.Several lanes can operate together to provide a multi- lane link. Multi-laning increases the data-rate to well over 20 Gbits/s.This paper details the current state of SpaceFibre which is now in the process of formal standardisation by the European Cooperation for Space Standardization (ECSS). The multi-lane layer of SpaceFibre is then described.

Research of glass fibre used in the electromagnetic wave shielding and absorption composite material

NASA Astrophysics Data System (ADS)

Xu, M.; Jia, F.; Bao, H. Q.; Cui, K.; Zhang, F.

2016-07-01

Electromagnetic shielding and absorption composite material plays an important role in the defence and economic field. Comparing with other filler, Glass fibre and its processed product—metal-coated glass fibre can greatly reduce the material's weight and costs, while it still remains the high strength and the electromagnetic shielding effectiveness. In this paper, the electromagnetic absorption mechanism and the reflection mechanism have been investigated as a whole, and the shielding effectiveness of the double-layer glass fibre composite material is mainly focused. The relationship between the shielding effectiveness and the filled glass fibre as well as its metal-coated product's parameters has also been studied. From the subsequent coaxial flange and anechoic chamber analysis, it can be confirmed that the peak electromagnetic shielding effectiveness of this double-layer material can reach -78dB while the bandwidth is from 2GHz to 18GHz.

Influence of fibre design and curvature on crosstalk in multi-core fibre

NASA Astrophysics Data System (ADS)

Egorova, O. N.; Astapovich, M. S.; Melnikov, L. A.; Salganskii, M. Yu; Mishkin, V. P.; Nishchev, K. N.; Semjonov, S. L.; Dianov, E. M.

2016-03-01

We have studied the influence of cross-sectional structure and bends on optical cross-talk in a multicore fibre. A reduced refractive index layer produced between the cores of such fibre with a small centre-to-centre spacing between neighbouring cores (27 μm) reduces optical cross-talk by 20 dB. The cross-talk level achieved, 30 dB per kilometre of the length of the multicore fibre, is acceptable for a number of applications where relatively small lengths of fibre are needed. Moreover, a significant decrease in optical cross-talk has been ensured by reducing the winding diameter of multicore fibres with identical cores.

Design and development of novel bandages for compression therapy.

PubMed

Rajendran, Subbiyan; Anand, Subhash

2003-03-01

During the past few years there have been increasing concerns relating to the performance of bandages, especially their pressure distribution properties for the treatment of venous leg ulcers. This is because compression therapy is a complex system and requires two or multi-layer bandages, and the performance properties of each layer differs from other layers. The widely accepted sustained graduated compression mainly depends on the uniform pressure distribution of different layers of bandages, in which textile fibres and bandage structures play a major role. This article examines how the fibres, fibre blends and structures influence the absorption and pressure distribution properties of bandages. It is hoped that the research findings will help medical professionals, especially nurses, to gain an insight into the development of bandages. A total of 12 padding bandages have been produced using various fibres and fibre blends. A new technique that would facilitate good resilience and cushioning properties, higher and more uniform pressure distribution and enhanced water absorption and retention was adopted during the production. It has been found that the properties of developed padding bandages, which include uniform pressure distribution around the leg, are superior to existing commercial bandages and possess a number of additional properties required to meet the criteria stipulated for an ideal padding bandage. Results have indicated that none of the mostly used commercial padding bandages provide the required uniform pressure distribution around the limb.

Thermal effects on an embedded grating sensor in an FRP structure

NASA Astrophysics Data System (ADS)

Lau, Kin-tak; Yuan, Libo; Zhou, Li-min

2001-08-01

Much research has been carried out in the field of using optical fibre sensors as internal strain and temperature measuring devices for advanced composite structures in recent years. The specific application is the use of embedded optical fibre sensors for smart composite reinforcement for strain monitoring in an innovative civil engineering structure, particularly for the structure after rehabilitation. Researchers have also paid attention to using the optical fibre sensor for monitoring the condition of composite materials during manufacturing and curing processes. However, heat induced in the curing process may influence the accuracy of measurement and eventuate in causing damage at the bond interface between the optical fibre and the surrounding matrix material because of the different thermal properties of silica fibre and composite materials. In this paper, a simple theoretical model is introduced to determine the interfacial properties of the embedded optical fibre system in composite laminates with different values of the coefficient of thermal expansion under different temperature environments. A finite-element method is used to compare the result from the theoretical prediction. The results show that the maximum shear stress in the coating layer decreases with increasing surrounding temperature when the optical fibre is embedded into carbon and Kevlar fibre composites. In contrast, increasing the temperature when the optical fibre is embedded into glass fibre composite results in the increase of maximum shear stress of the material. The compaction pressure distribution along the circumference of the coating layer also varies with temperature.

Towards reinforcement solutions for urban fibre/fabric waste using bio-based biodegradable resins.

NASA Astrophysics Data System (ADS)

Agrawal, Pramod; Hermes, Alina; Bapeer, Solaf; Luiken, Anton; Bouwhuis, Gerrit; Brinks, Ger

2017-10-01

The main research question is how to systematically define and characterize urban textile waste and how to effectively utilise it to produce reinforcement(s) with selected bio-based biodegradable resin(s). Several composite samples have been produced utilising predominantly natural and predominantly synthetic fibres by combining loose fibres with PLA, nonwoven fabric with PLA, woven fabric with PLA, two-layer composite & four-layer composite samples. Physio-chemical characterisations according to the established standards have been conducted. The present work is a step toward the circular economy and closing the loop in textile value chain.

Repeatability and Reproducibility of Retinal Nerve Fiber Layer Parameters Measured by Scanning Laser Polarimetry with Enhanced Corneal Compensation in Normal and Glaucomatous Eyes

PubMed Central

Ara, Mirian; Pajarin, Ana B.

2015-01-01

Objective. To assess the intrasession repeatability and intersession reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness parameters measured by scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) in healthy and glaucomatous eyes. Methods. One randomly selected eye of 82 healthy individuals and 60 glaucoma subjects was evaluated. Three scans were acquired during the first visit to evaluate intravisit repeatability. A different operator obtained two additional scans within 2 months after the first session to determine intervisit reproducibility. The intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) were calculated for all SLP parameters in both groups. Results. ICCs ranged from 0.920 to 0.982 for intravisit measurements and from 0.910 to 0.978 for intervisit measurements. The temporal-superior-nasal-inferior-temporal (TSNIT) average was the highest (0.967 and 0.946) in normal eyes, while nerve fiber indicator (NFI; 0.982) and inferior average (0.978) yielded the best ICC in glaucomatous eyes for intravisit and intervisit measurements, respectively. All COVs were under 10% in both groups, except NFI. TSNIT average had the lowest COV (2.43%) in either type of measurement. Intervisit TRT ranged from 6.48 to 12.84. Conclusions. The reproducibility of peripapillary RNFL measurements obtained with SLP-ECC was excellent, indicating that SLP-ECC is sufficiently accurate for monitoring glaucoma progression. PMID:26185762

Retinal nerve fiber layer reflectance for early glaucoma diagnosis.

PubMed

Liu, Shuang; Wang, Bingqing; Yin, Biwei; Milner, Thomas E; Markey, Mia K; McKinnon, Stuart J; Rylander, Henry G

2014-01-01

Compare performance of normalized reflectance index (NRI) and retinal nerve fiber layer thickness (RNFLT) parameters determined from optical coherence tomography (OCT) images for glaucoma and glaucoma suspect diagnosis. Seventy-five eyes from 71 human subjects were studied: 33 controls, 24 glaucomatous, and 18 glaucoma-suspects. RNFLT and NRI maps were measured using 2 custom-built OCT systems and the commercial instrument RTVue. Using area under the receiver operating characteristic curve, RNFLT and NRI measured in 7 RNFL locations were analyzed to distinguish between control, glaucomatous, and glaucoma-suspect eyes. The mean NRI of the control group was significantly larger than the means of glaucomatous and glaucoma-suspect groups in most RNFL locations for all 3 OCT systems (P<0.05 for all comparisons). NRI performs significantly better than RNFLT at distinguishing between glaucoma-suspect and control eyes using RTVue OCT (P=0.008). The performances of NRI and RNFLT for classifying glaucoma-suspect versus control eyes were statistically indistinguishable for PS-OCT-EIA (P=0.101) and PS-OCT-DEC (P=0.227). The performances of NRI and RNFLT for classifying glaucomatous versus control eyes were statistically indistinguishable (PS-OCT-EIA: P=0.379; PS-OCT-DEC: P=0.338; RTVue OCT: P=0.877). NRI is a promising measure for distinguishing between glaucoma-suspect and control eyes and may indicate disease in the preperimetric stage. Results of this pilot clinical study warrant a larger study to confirm the diagnostic power of NRI for diagnosing preperimetric glaucoma.

Linezolid-induced optic neuropathy with a rare pathological change in the inner retina.

PubMed

Ishii, Nobuhito; Kinouchi, Reiko; Inoue, Masatomo; Yoshida, Akitoshi

2016-12-01

We report a case of linezolid-induced optic neuropathy with transient microcystic spaces in the inner retina. We observed the retina using Fourier-domain optical coherence tomography (FD-OCT) in a patient with linezolid-induced optic neuropathy. A 49-year-old woman presented to our department with a 1-week history of bilateral photophobia. At the first visit, her best-corrected visual acuity (VA) was 0.6 in the right eye and 0.5 in the left eye. She had moderate optic disk edema and central scotomas bilaterally. FD-OCT showed bilateral microcystic spaces in the retina. Microcystic spaces were seen in the retinal nerve fiber layer (RNFL) and at the border of the RNFL and the retinal ganglion cell layer. Magnetic resonance imaging and laboratory tests showed no positive findings except for an elevated lactic acid level. One week after the first visit, the VA levels decreased to 0.06 and 0.07 in the right and left eyes, respectively. Because the patient had a 7-month history of linezolid treatment for persistent pyogenic arthritis, we suspected linezolid-induced optic neuropathy and immediately terminated treatment with this drug. The optic disk edema and the microcystic spaces in the retina resolved, and the VA improved to 1.2 at 6 weeks after linezolid withdrawal. Microcystic spaces, which resolved with linezolid withdrawal, were observed in linezolid-induced optic neuropathy. The microcystic spaces in the inner retina can be the first retinal sign of some optic neuropathies.

Evaluation of posterior ocular changes using enhanced depth imaging-optical coherence tomography in patients with obstructive sleep apnea syndrome.

PubMed

Yuvacı, İsa; Pangal, Emine; Bayram, Nurettin; Yüksel, Sevgi Arık; Alabay, Bedirhan; Ağadayı, Alperen; Sırakaya, Ender; Gülhan, Ahmet

2016-01-01

Evaluation of the nerve fiber thicknesses of the macula, choroid, and retina using the apnea-hypopnea index in individuals with obstructive sleep apnea syndrome (OSAS) without systemic components. Prospective, controlled study. The central macular, choroidal, and retinal nerve fiber layer (RNFL) thicknesses were evaluated using enhanced depth imaging-spectral domain optical coherence tomography in individuals with OSAS. In people with severe OSAS who had received treatment, posterior ocular structures were examined over 3 months (4th and 12th weeks), and changes were evaluated. Only the right eyes of the participants were evaluated in the study. A total of 72 people were involved in the study, with 18 in the control group and 19 with mild, 16 with moderate, and 19 with severe OSAS. No significant difference was found among the groups in terms of demographic measures. No significant differences were found among the groups in terms of the measures of central macular, central subfoveal choroidal (CSCT), temporal choroidal, nasal choroidal, and RNFL thicknesses. In severe OSAS cases in which treatment was administered, although subjective clinical recovery was observed, statistically significant thinning was detected during the 3-month follow-up period in the CSCT, general RNFL, as well as in the inferior and superior nasal quadrants, and temporal superior quadrant (p=0.005, p=0.009, p=0.039, p=0.003, and p=0.02, respectively). In the group with severe OSAS, thinning in some posterior ocular tissues was observed. Although patients with severe OSAS may experience clinical recovery, we recommend that they would be followed up in terms of ocular ischemic injury.

Optical coherence tomography for glaucoma diagnosis: An evidence based meta-analysis.

PubMed

Kansal, Vinay; Armstrong, James J; Pintwala, Robert; Hutnik, Cindy

2018-01-01

Early detection, monitoring and understanding of changes in the retina are central to the diagnosis of glaucomatous optic neuropathy, and vital to reduce visual loss from this progressive condition. The main objective of this investigation was to compare glaucoma diagnostic accuracy of commercially available optical coherence tomography (OCT) devices (Zeiss Stratus, Zeiss Cirrus, Heidelberg Spectralis and Optovue RTVue, and Topcon 3D-OCT). 16,104 glaucomatous and 11,543 normal eyes reported in 150 studies. Between Jan. 2017 and Feb 2017, MEDLINE®, EMBASE®, CINAHL®, Cochrane Library®, Web of Science®, and BIOSIS® were searched for studies assessing glaucoma diagnostic accuracy of the aforementioned OCT devices. Meta-analysis was performed pooling area under the receiver operating characteristic curve (AUROC) estimates for all devices, stratified by OCT type (RNFL, macula), and area imaged. 150 studies with 16,104 glaucomatous and 11,543 normal control eyes were included. Key findings: AUROC of glaucoma diagnosis for RNFL average for all glaucoma patients was 0.897 (0.887-0.906, n = 16,782 patient eyes), for macula ganglion cell complex (GCC) was 0.885 (0.869-0.901, n = 4841 eyes), for macula ganglion cell inner plexiform layer (GCIPL) was 0.858 (0.835-0.880, n = 4211 eyes), and for total macular thickness was 0.795 (0.754-0.834, n = 1063 eyes). The classification capability was similar across all 5 OCT devices. More diagnostically favorable AUROCs were demonstrated in patients with increased glaucoma severity. Diagnostic accuracy of RNFL and segmented macular regions (GCIPL, GCC) scans were similar and higher than total macular thickness. This study provides a synthesis of contemporary evidence with features of robust inclusion criteria and large sample size. These findings may provide guidance to clinicians when navigating this rapidly evolving diagnostic area characterized by numerous options.

Repeatability of Spectral Domain Optical Coherence Tomography Measurements in High Myopia.

PubMed

Rao, Harsha L; Kumar, Addepalli U; Bonala, Sampath R; Yogesh, Kadam; Lakshmi, Bodduluri

2016-05-01

The purpose of this study was to compare the repeatability of spectral domain optical coherence tomography (SDOCT) parameters in high-myopic and emmetropic healthy subjects, and to evaluate the influence of axial length on the repeatability of SDOCT parameters in high myopia. In a prospective study, 93 eyes of 63 high-myopic subjects (spherical refractive error, -6 to -12 D; median age, 25 y) and 28 eyes of 14 emmetropic (spherical refractive error, 0 D; median age, 30 y) subjects underwent optic nerve head, retinal nerve fiber layer (RNFL), and ganglion cell complex imaging with SDOCT. For the repeatability analysis, 31 eyes of 31 high-myopic subjects and 14 eyes of 14 emmetropic subjects underwent 3 repeated scans in the same session. Among the optic nerve head parameters, within-subject coefficient of variation (CVw) measurements of the disc area (0.6% vs. 0.2%), rim area (8.7 vs. 2.8), and rim volume (16.7 vs. 8.9) were significantly larger (worse) in high-myopic compared with the emmetropic subjects. CVw measurements of all RNFL (range, 1.7 to 22.4) and ganglion cell complex (range, 1.8 to 2.5) parameters in high-myopic subjects were comparable to that in emmetropic subjects (2.4 to 24.0 and 1.7 to 2.0, respectively). Axial length significantly affected the CVw of nasal (coefficient, 0.01; P=0.04) and average RNFL (coefficient, 0.004; P=0.001) parameters but not that of the other SDOCT parameters. Repeatabilities of most of the SDOCT parameters in high-myopic subjects were good and comparable to that of emmetropic subjects. This suggests that SDOCT can be useful for following up high-myopic glaucoma patients to detect progression.

Influence of optic disc leakage on objective optic nerve head assessment in patients with uveitis.

PubMed

Heinz, Carsten; Kogelboom, Katy; Heiligenhaus, Arnd

2016-02-01

Secondary glaucoma is a common complication in patients with uveitis. Heidelberg Retina Tomography (HRT) and retinal nerve fiber layer (RNFL) thickness on optical coherence tomography (OCT) are widely used for examining optic nerve head changes. We evaluated these parameters in patients with uveitis and secondary glaucoma and with inflammatory papillary leakage on fluorescein angiography. Prospective single-center analysis of patients with uveitis, evaluating the impact of optic disc leakage on objective optic disc imaging parameters. Overall, 96 eyes of 59 patients were included. Papillary leakage was found in 42 eyes (43.8 %), and secondary glaucoma was found in 41 eyes (42.7 %). Glaucoma and papillary leakage were present in 12 (29 %) eyes with leakage and in 29 (54 %) eyes without leakage (p = 0.023). Neuroretinal rim area (p = 0.004), rim volume on HRT (p = 0.004), and RNFL thickness on OCT (p = 0.0008) were significantly increased in eyes with papillary leakage, while RNFL on HRT was unchanged (p = 0.255). When only eyes with normal IOP were examined, all objective parameters on OCT and HRT were significantly increased, whereas in eyes with secondary glaucoma, there was only a trend in the same direction, which did not reach significance. A comparison of eyes with secondary glaucoma and optic disc leakage to normal eyes with no glaucoma or leakage revealed no difference in any of the parameters. The objective parameters of optic nerve head imaging tools are significantly influenced by papillary leakage. In patients with secondary glaucoma and papillary leakage, these techniques are unable to detect and monitor glaucomatous damage.

Multifocal electroretinogram (MFERG) evaluation of laser-induced secondary damage in the non-human primate (NHP)

NASA Astrophysics Data System (ADS)

Zwick, Harry; Stuck, Bruce E.; Akers, A.; Edsall, Peter; DiCarlo, Cheryl D.; Lund, David J.

2005-04-01

Laser induced retinal damage may involve primary injury to the central retina and secondary damage, including intraretinal scar formation (IRSF) retinal traction (RT) and retinal nerve fiber layer injury (RNFL). We have evaluated these laser induced retinal pathologies with MFERG in non-human primates (NHPs) with a Veris (4.9) MFERG system 103 Hexagons, centered on the macula with non-scaled arrays and in one NHP with a 2-frame/M-step sequence to assess long term exposure effects within the RNFL. Chemical restraint was achieved using Ketamine stability HCL (10 mg/kg IM) and Propofol (0.5 mg-1.2/Kg/min via syringe pump). Peribulbar eye blocks were performed using 2% lidocain or a mixture of 2% Lidocain/Marcain (monitored ocular motility was less than 40 microns in retinal space). Primary and secondary damage effects were induced with either q-switched single pulse Neodymium (1064 nm, 1.0 mJ) or Argon CW (10 to 1000 msec, 10-150 mW). MFERG demonstrated capability to detect primary and secondary induced retinal damage in both 1st and 2nd order kernels. Primary and secondary damage in the central retina was often suppressed in amplitude and with longer latencies relative to the MFERG norm. Preliminary investigations in one NHP with Primary and secondary RNFL damage at 9 to 14 months showed recovery with non-scaled array one frame / M-step sequence but demonstrated significant abnormalities for a two frame/ M-step sequence. Utilization of advanced Veris recording parameters involving spatial and temporal manipulation of the stimulus parameters can improve detection of functional deficits induced by focal laser retinal injury.

Developing new automated alternation flicker using optic disc photography for the detection of glaucoma progression

PubMed Central

Ahn, J; Yun, I S; Yoo, H G; Choi, J-J; Lee, M

2017-01-01

Purpose To evaluate a progression-detecting algorithm for a new automated matched alternation flicker (AMAF) in glaucoma patients. Methods Open-angle glaucoma patients with a baseline mean deviation of visual field (VF) test>−6 dB were included in this longitudinal and retrospective study. Functional progression was detected by two VF progression criteria and structural progression by both AMAF and conventional comparison methods using optic disc and retinal nerve fiber layer (RNFL) photography. Progression-detecting performances of AMAF and the conventional method were evaluated by an agreement between functional and structural progression criteria. RNFL thickness changes measured by optical coherence tomography (OCT) were compared between progressing and stable eyes determined by each method. Results Among 103 eyes, 47 (45.6%), 21 (20.4%), and 32 (31.1%) eyes were evaluated as glaucoma progression using AMAF, the conventional method, and guided progression analysis (GPA) of the VF test, respectively. The AMAF showed better agreement than the conventional method, using GPA of the VF test (κ=0.337; P<0.001 and κ=0.124; P=0.191, respectively). The rates of RNFL thickness decay using OCT were significantly different between the progressing and stable eyes when progression was determined by AMAF (−3.49±2.86 μm per year vs −1.83±3.22 μm per year; P=0.007) but not by the conventional method (−3.24±2.42 μm per year vs −2.42±3.33 μm per year; P=0.290). Conclusions The AMAF was better than the conventional comparison method in discriminating structural changes during glaucoma progression, and showed a moderate agreement with functional progression criteria. PMID:27662466

Measurement of Optic Disc Cup Surface Depth Using Cirrus HD-OCT.

PubMed

Kim, Young Kook; Ha, Ahnul; Lee, Won June; Jeoung, Jin Wook; Park, Ki Ho

2017-12-01

To introduce the measurement method of optic disc cup surface depth using spectral-domain optical coherence tomography (SD-OCT) and then evaluate the rates of cup surface depression at 3 different stages of glaucoma. We retrospectively identified 52 eyes with preperimetric glaucoma, 56 with mild-or-moderate glaucoma and 50 with severe glaucoma and followed them for at least 48 months. Eyes were imaged using SD-OCT (Cirrus HD-OCT) at 12-month intervals. The mean cup surface depth was calculated using the following formula: Cup volume/(disc area×average cup-to-disc ratio)-200 μm. The rates of mean cup surface depression (μm/y) were significantly greater in mild-or-moderate glaucoma (-7.96±1.03) than in preperimetric (-3.11±0.61) and severe glaucoma (-0.70±0.12; all P<0.001). The percentile rates of mean cup surface depression (%/y) were significantly greater than those of average of retinal nerve fiber layer (RNFL) thinning (%/y) in preperimetric glaucoma (-1.64±0.12 vs. -1.11±0.07; P<0.001) and mild-or-moderate glaucoma (-4.20±0.33 vs. -3.14±0.19; P<0.001); and conversely, in severe glaucoma, mean cup surface depth changed slower than did average RNFL thickness (-0.64±0.06 vs. -0.75±0.08%/y; P<0.001). In early-to-moderate glaucoma, the cup surface depth changed faster than did the RNFL thickness. These results signify the possibility that SD-OCT-based estimation of cup surface depth might be useful for monitoring of glaucoma development and progression.

Multifocal Visual Evoked Potential in Eyes With Temporal Hemianopia From Chiasmal Compression: Correlation With Standard Automated Perimetry and OCT Findings.

PubMed

Sousa, Rafael M; Oyamada, Maria K; Cunha, Leonardo P; Monteiro, Mário L R

2017-09-01

To verify whether multifocal visual evoked potential (mfVEP) can differentiate eyes with temporal hemianopia due to chiasmal compression from healthy controls. To assess the relationship between mfVEP, standard automated perimetry (SAP), and Fourier domain-optical coherence tomography (FD-OCT) macular and peripapillary retinal nerve fiber layer (RNFL) thickness measurements. Twenty-seven eyes with permanent temporal visual field (VF) defects from chiasmal compression on SAP and 43 eyes of healthy controls were submitted to mfVEP and FD-OCT scanning. Multifocal visual evoked potential was elicited using a stimulus pattern of 60 sectors and the responses were averaged for the four quadrants and two hemifields. Optical coherence tomography macular measurements were averaged in quadrants and halves, while peripapillary RNFL thickness was averaged in four sectors around the disc. Visual field loss was estimated in four quadrants and each half of the 24-2 strategy test points. Multifocal visual evoked potential measurements in the two groups were compared using generalized estimated equations, and the correlations between mfVEP, VF, and OCT findings were quantified. Multifocal visual evoked potential-measured temporal P1 and N2 amplitudes were significantly smaller in patients than in controls. No significant difference in amplitude was observed for nasal parameters. A significant correlation was found between mfVEP amplitudes and temporal VF loss, and between mfVEP amplitudes and the corresponding OCT-measured macular and RNFL thickness parameters. Multifocal visual evoked potential amplitude parameters were able to differentiate eyes with temporal hemianopia from controls and were significantly correlated with VF and OCT findings, suggesting mfVEP is a useful tool for the detection of visual abnormalities in patients with chiasmal compression.

Functional and morphological assessment of ocular structures and follow-up of patients with early-stage Parkinson's disease.

PubMed

Hasanov, Samir; Demirkilinc Biler, Elif; Acarer, Ahmet; Akkın, Cezmi; Colakoglu, Zafer; Uretmen, Onder

2018-05-09

To evaluate and follow-up of functional and morphological changes of the optic nerve and ocular structures prospectively in patients with early-stage Parkinson's disease. Nineteen patients with a diagnosis of early-stage Parkinson's disease and 19 age-matched healthy controls were included in the study. All participants were examined minimum three times at the intervals of at least 6 month following initial examination. Pattern visually evoked potentials (VEP), contrast sensitivity assessments at photopic conditions, color vision tests with Ishihara cards and full-field visual field tests were performed in addition to measurement of retinal nerve fiber layer (RNFL) thickness of four quadrants (top, bottom, nasal, temporal), central and mean macular thickness and macular volumes. Best corrected visual acuity was observed significantly lower in study group within all three examinations. Contrast sensitivity values of the patient group were significantly lower in all spatial frequencies. P100 wave latency of VEP was significantly longer, and amplitude was lower in patient group; however, significant deterioration was not observed during the follow-up. Although average peripapillary RNFL thickness was not significant between groups, RNFL thickness in the upper quadrant was thinner in the patient group. While there was no difference in terms of mean macular thickness and total macular volume values between the groups initially, a significant decrease occurred in the patient group during the follow-up. During the initial and follow-up process, a significant deterioration in visual field was observed in the patient group. Structural and functional disorders shown as electro-physiologically and morphologically exist in different parts of visual pathways in early-stage Parkinson's disease.

Longitudinal Change Detected by Spectral Domain Optical Coherence Tomography in the Optic Nerve Head and Peripapillary Retina in Experimental Glaucoma

PubMed Central

Strouthidis, Nicholas G.; Fortune, Brad; Yang, Hongli; Sigal, Ian A.

2011-01-01

Purpose. To investigate whether longitudinal changes deep within the optic nerve head (ONH) are detectable by spectral domain optical coherence tomography (SDOCT) in experimental glaucoma (EG) and whether these changes are detectable at the onset of Heidelberg Retina Tomography (HRT; Heidelberg Engineering, Heidelberg, Germany)–defined surface topography depression. Methods. Longitudinal SDOCT imaging (Spectralis; Heidelberg Engineering) was performed in both eyes of nine rhesus macaques every 1 to 3 weeks. One eye of each underwent trabecular laser-induced IOP elevation. Four masked operators delineated internal limiting membrane (ILM), retinal nerve fiber layer (RNFL), Bruch's membrane/retinal pigment epithelium (BM/RPE), neural canal opening (NCO), and anterior lamina cribrosa surface (ALCS) by using custom software. Longitudinal changes were assessed and compared between the EG and control (nonlasered) eyes at the onset of HRT-detected surface depression (follow-up 1; [FU1]) and at the most recent image (follow-up 2; [FU2]). Results. Mean IOP in EG eyes was 7.1 to 24.6 mm Hg at FU1 and 13.5 to 31.9 mm Hg at FU2. In control eyes, the mean IOP was 7.2 to 12.6 mm Hg (FU1) and 8.9 to 16.0 mm Hg (FU2). At FU1, neuroretinal rim decreased and ALCS depth increased significantly (paired t-test, P < 0.01); no change in RNFL thickness was detected. At FU2, however, significant prelaminar tissue thinning, posterior displacement of NCO, and RNFL thinning were observed. Conclusions. Longitudinal SDOCT imaging can detect deep ONH changes in EG eyes, the earliest of which are present at the onset of HRT-detected ONH surface height depression. These parameters represent realistic targets for SDOCT detection of glaucomatous progression in human subjects. PMID:21217108

Influence of fibre design and curvature on crosstalk in multi-core fibre

DOE Office of Scientific and Technical Information (OSTI.GOV)

Egorova, O N; Astapovich, M S; Semjonov, S L

2016-03-31

We have studied the influence of cross-sectional structure and bends on optical cross-talk in a multicore fibre. A reduced refractive index layer produced between the cores of such fibre with a small centre-to-centre spacing between neighbouring cores (27 μm) reduces optical cross-talk by 20 dB. The cross-talk level achieved, 30 dB per kilometre of the length of the multicore fibre, is acceptable for a number of applications where relatively small lengths of fibre are needed. Moreover, a significant decrease in optical cross-talk has been ensured by reducing the winding diameter of multicore fibres with identical cores. (fiber optics)

Retinal neurodegeneration in patients with type 1 diabetes mellitus: the role of glycemic variability.

PubMed

Picconi, Fabiana; Parravano, Mariacristina; Ylli, Dorina; Pasqualetti, Patrizio; Coluzzi, Sara; Giordani, Ilaria; Malandrucco, Ilaria; Lauro, Davide; Scarinci, Fabio; Giorno, Paola; Varano, Monica; Frontoni, Simona

2017-05-01

Recent studies have identified neuroretinal abnormalities in persons affected by diabetes mellitus, before the onset of microvascular alterations. However, the role of glycemic variability (GV) on early retinal neurodegeneration is still not clarified. To explore the relationship between glycemic control and neuroretinal characteristics, 37 persons with Type 1 diabetes mellitus (Type 1 DM) divided into two groups with no signs (noRD) and with mild non-proliferative diabetic retinopathy (NPDR) compared to 13 healthy control participants (C) were recruited. All persons underwent an optical coherence tomography with automatic segmentation of all neuroretinal layers. Measurements of mean of nasal (N)/temporal (T)/superior (S)/inferior (I) macular quadrants for individual layer were also calculated. Metabolic control was evaluated by glycated hemoglobin (HbA1c), and indexes of GV were calculated from continuous glucose monitoring. The difference among the three groups in terms of RNFL thickness was significantly dependent on quadrant (F(6;132) = 2.315; p = 0.037). This interaction was due to a specific difference in RNFL-N thickness, where both Type 1 DM groups showed a similar reduction versus C (-3.9 for noDR and -4.9 for NPDR), without any relevant difference between them (-1.0). Inner nuclear layer (INL) was increased in all quadrants in the two Type 1 DM groups compared to C (mean difference = 7.73; 95% CI: 0.32-15.14, p = 0.043; mean difference = 7.74; 95% CI: 0.33-15.15, p = 0.043, respectively). A negative correlation between RNFL-N and low blood glucose index (r = -0.382, p = 0.034) and positive correlation between INL and continuous overall net glycemic action -1, -2, -4 h (r = 0.40, p = 0.025; r = 0.39, p = 0.031; r = 0.41, p = 0.021, respectively) were observed in Type 1 DM patients. The triglycerides were positively and significantly correlated to INL (r = 0.48, p = 0.011), in Type 1 DM subjects. GV and triglycerides resulted both independent predictors of increased INL thickness. No correlation was found with HbA1c. Early structural damage of neuroretina in persons with Type 1 DM patients is related to glucose fluctuations. GV should be addressed, even in the presence of a good metabolic control.

Diagnostic capability of retinal thickness measures in diabetic peripheral neuropathy.

PubMed

Srinivasan, Sangeetha; Pritchard, Nicola; Sampson, Geoff P; Edwards, Katie; Vagenas, Dimitrios; Russell, Anthony W; Malik, Rayaz A; Efron, Nathan

To examine the diagnostic capability of the full retinal and inner retinal thickness measures in differentiating individuals with diabetic peripheral neuropathy (DPN) from those without neuropathy and non-diabetic controls. Individuals with (n=44) and without (n=107) diabetic neuropathy and non-diabetic control (n=42) participants underwent spectral domain optical coherence tomography (SDOCT). Retinal thickness in the central 1mm zone (including the fovea), parafovea and perifovea was assessed in addition to ganglion cell complex (GCC) global loss volume (GCC GLV) and focal loss volume (GCC FLV), and retinal nerve fiber layer (RNFL) thickness. Diabetic neuropathy was defined using a modified neuropathy disability score (NDS) recorded on a 0-10 scale, wherein, NDS ≥3 indicated neuropathy and NDS indicated <3 no neuropathy. Diagnostic performance was assessed by areas under the receiver operating characteristic curves (AUCs), 95 per cent confidence intervals (CI), sensitivities at fixed specificities, positive likelihood ratio (+LR), negative likelihood ratio (-LR) and the cut-off points for the best AUCs obtained. The AUC for GCC FLV was 0.732 (95% CI: 0.624-0.840, p<0.001) with a sensitivity of 53% and specificity of 80% for differentiating DPN from controls. Evaluation of the LRs showed that GCC FLV was associated with only small effects on the post-test probability of the disease. The cut-off point calculated using the Youden index was 0.48% (67% sensitivity and 73% specificity) for GCC FLV. For distinguishing those with neuropathy from those without neuropathy, the AUCs of retinal parameters ranged from 0.508 for the central zone to 0.690 for the inferior RNFL thickness. For distinguishing those with moderate or advanced neuropathy from those with mild or no neuropathy, the inferior RNFL thickness demonstrated the highest AUC of 0.820, (95% CI: 0.731-0.909, p<0.001) with a sensitivity of 69% and 80% specificity. The cut-off-point for the inferior RNFL thickness was 97μm, with 81% sensitivity and 72% specificity. The GCC FLV can differentiate individuals with diabetic neuropathy from healthy controls, while the inferior RNFL thickness is able to differentiate those with greater degrees of neuropathy from those with mild or no neuropathy, both with an acceptable level of accuracy. Optical coherence tomography represents a non-invasive technology that aids in detection of retinal structural changes in patients with established diabetic neuropathy. Further refinement of the technique and the analytical approaches may be required to identify patients with minimal neuropathy. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Distribution of cocaine- and amphetamine-regulated transcript in the hippocampal formation of the guinea pig and domestic pig.

PubMed

Kolenkiewicz, M; Robak, A; Równiak, M; Bogus-Nowakowska, K; Całka, J; Majewski, M

2009-02-01

This study provides a detailed description concerning the distribution of cocaineand amphetamine-regulated transcript (CART) subunits - CART(61-102) and rhCART(28-116) - in the hippocampal formation (HF) of the guinea pig and domestic pig, focussing on the dentate gyrus (DG) and hippocampus proper (HP). Although in both studied species CART-immunoreactive (CART-IR) neuronal somata and processes were present generally in the same layers, some species-specific differences were still found. In the granular layer (GL) of both species, the ovalshaped neurons and some thick varicose fibres were encountered. In the guinea pig there was an immunoreactive "band of dots", probably representing crosssectioned terminals within the DG molecular layer (MOL), whereas in the domestic pig, some varicose fibres were detected, thus suggesting a different orientation of, at least, some nerve terminals. Furthermore, some CART-positive cells and fibres were observed in the hilus (HL) of the guinea pig, whereas in the analogical part of the domestic pig only nerve terminals were labelled. In both species, in the pyramidal layer (PL) of the hippocampus proper, CART-IR triangular somata were observed in the CA3 sector, as well as some positive processes in MOL; however, a few immunoreactive perikarya were found only in the CA1 sector of the guinea pig. As regards the localization patterns of two isoforms of CART in the guinea pig, both peptide fragments were present simultaneously in each of the labelled neurons or fibres, whereas in the domestic pig three types of fibres may be distinguished within the area of the DG. In the hilus and MOL of the dentate gyrus, there were fibres expressing both isoforms of CART in their whole length (fibres of the first type). Fibres of the second type (in GL) coexpressed both peptides only on their short segments, and the last ones (in MOL) expressed solely rhCART(28-116). These results indicate that the distribution of the two CART isoforms are specifically related, thus the relationship between the two CART isoforms may imply different metabolic profiles of CART-expressing neurons.

The effect of different fibre volume fraction on mechanical properties of banana/pineapple leaf (PaLF)/glass hybrid composite

NASA Astrophysics Data System (ADS)

Hanafee, Z. M.; Khalina, A.; Norkhairunnisa, M.; Syams, Z. Edi; Liew, K. E.

2017-09-01

This paper investigates the effect of fibre volume fraction on mechanical properties of banana-pineapple leaf (PaLF)-glass reinforced epoxy resin under tensile loading. Uniaxial tensile tests were carried out on specimens with different fibre contents (30%, 40%, 50% in weight). The composite specimens consists of 13 different combinations. The effect of hybridisation between synthetic and natural fibre onto tensile properties was determined and the optimum fibre volume fraction was obtained at 50% for both banana and PaLF composites. Additional 1 layer of woven glass fibre increased the tensile strength of banana-PaLF composite up to 85%.

Two innovative solutions based on fibre concrete blocks designed for building substructure

NASA Astrophysics Data System (ADS)

Pazderka, J.; Hájek, P.

2017-09-01

Using of fibers in a high-strength concrete allows reduction of the dimensions of small precast concrete elements, which opens up new ways of solution for traditional construction details in buildings. The paper presents two innovative technical solutions for building substructure: The special shaped plinth block from fibre concrete and the fibre concrete elements for new technical solution of ventilated floor. The main advantages of plinth block from fibre concrete blocks (compared with standard plinth solutions) is: easier and faster assembly, higher durability and thanks to the air cavity between the vertical part of the block, the building substructure reduced moisture level of structures under the waterproofing layer and a comprehensive solution to the final surface of building plinth as well as the surface of adjacent terrain. The ventilated floor based on fibre concrete precast blocks is an attractive structural alternative for tackling the problem of increased moisture in masonry in older buildings, lacking a functional waterproof layer in the substructure.

A neural network to improve dim-light vision? Dendritic fields of first-order interneurons in the nocturnal bee Megalopta genalis.

PubMed

Greiner, Birgit; Ribi, Willi A; Warrant, Eric J

2005-11-01

Using the combined Golgi-electron microscopy technique, we have determined the three-dimensional dendritic fields of the short visual fibres (svf 1-3) and first-order interneurons or L-fibres (L1-4) within the first optic ganglion (lamina) of the nocturnal bee Megalopta genalis. Serial cross sections have revealed that the svf type 2 branches into one adjacent neural unit (cartridge) in layer A, the most distal of the three lamina layers A, B and C. All L-fibres, except L1-a, exhibit wide lateral branching into several neighbouring cartridges. L1-b shows a dendritic field of seven cartridges in layers A and C, dendrites of L2 target 13 cartridges in layer A, L3 branches over a total of 12 cartridges in layer A and three in layer C and L4 has the largest dendritic field size of 18 cartridges in layer C. The number of cartridges reached by the respective L-fibres is distinctly greater in the nocturnal bee than in the worker honeybee and is larger than could be estimated from our previous Golgi-light microscopy study. The extreme dorso-ventrally oriented dendritic field of L4 in M. genalis may, in addition to its potential role in spatial summation, be involved in edge detection. Thus, we have shown that the amount of lateral spreading present in the lamina provides the anatomical basis for the required spatial summation. Theoretical and future physiological work should further elucidate the roles that this lateral spreading plays to improve dim-light vision in nocturnal insects.

Tensile properties of compressed moulded Napier/glass fibre reinforced epoxy composites

NASA Astrophysics Data System (ADS)

Fatinah, T. S.; Majid, M. S. Abdul; Ridzuan, M. J. M.; Hong, T. W.; Amin, N. A. M.; Afendi, M.

2017-10-01

This paper describes the experimental investigation of the tensile properties of compressed moulded Napier grass fibres reinforced epoxy composites. The effect of treatment 5% sodium hydroxide (NaOH) concentrated solution and hybridization of Napier with CSM E-glass fibres on tensile properties was also studied. The untreated and treated Napier fibres with 25% fibre loading were fabricated with epoxy resin by a cold press process. 7% fibre loading of CSM glass fibre was hybrid as the skin layer for 18% fibre loading of untreated Napier grass fibre. The tensile tests were conducted using Universal Testing Machine in accordance with ASTM D638. The tensile properties of the untreated Napier/epoxy composites were compared with treated Napier/epoxy and untreated Napier/CSM/epoxy composites. The results demonstrated that the tensile performance of untreated Napier fibre composites was significantly improved by both of the modification; alkali treatment and glass fibre hybridization. Napier grass fibres showed promising potentials to be used as reinforcement in the polymer based composites.

Surface modification of poly(vinylidene fluoride) hollow fibre membranes for biogas purification in a gas-liquid membrane contactor system.

PubMed

Jin, Pengrui; Huang, Chuan; Li, Jiaxiang; Shen, Yadong; Wang, Liao

2017-11-01

The wetting of hollow fibre membranes decreases the performance of the liquid-gas membrane contactor for CO 2 capture in biogas upgrading. To solve this problem, in this work, a poly(vinylidene fluoride) (PVDF) hollow fibre membrane for a liquid-gas membrane contactor was coated with a superhydrophobic layer composed of a combination of hydrophobic SiO 2 nanoparticles and polydimethylsiloxane (PDMS) by the method of spray deposition. A rough layer of SiO 2 deposited on the PVDF membrane resulted in an enhanced surface hydrophobicity. The surface structure of the pristine PVDF significantly affected the homogeneity of the generated SiO 2 layer. A uniform surface coating on the PVDF upper layer resulted from the presence of micrometre and nanometre-sized roughness on the surface of the PVDF membrane, which was achieved with a SiO 2 concentration of 4.44 mg ml -1 (0.2 g/45 ml) in the coating solution. As a result, the water contact angle of the modified surface was recorded as 155 ± 3°, which is higher than that of the pristine surface. The high contact angle is advantageous for reducing the wetting of the membrane. Additional mass transfer resistance was introduced by the superhydrophobic layer. In addition, continuous CO 2 absorption tests were carried out in original and modified PVDF hollow fibre membrane contactors, using monoethanolamine (MEA) solution as the absorbent. A long-term stability test revealed that the modified PVDF hollow fibre membrane contactor was able to outperform the original membrane contactor and demonstrated outstanding long-term stability, suggesting that spray deposition is a promising approach to obtain superhydrophobic PVDF membranes for liquid-gas membrane absorption.

Surface modification of poly(vinylidene fluoride) hollow fibre membranes for biogas purification in a gas–liquid membrane contactor system

PubMed Central

Huang, Chuan; Li, Jiaxiang; Shen, Yadong; Wang, Liao

2017-01-01

The wetting of hollow fibre membranes decreases the performance of the liquid–gas membrane contactor for CO2 capture in biogas upgrading. To solve this problem, in this work, a poly(vinylidene fluoride) (PVDF) hollow fibre membrane for a liquid–gas membrane contactor was coated with a superhydrophobic layer composed of a combination of hydrophobic SiO2 nanoparticles and polydimethylsiloxane (PDMS) by the method of spray deposition. A rough layer of SiO2 deposited on the PVDF membrane resulted in an enhanced surface hydrophobicity. The surface structure of the pristine PVDF significantly affected the homogeneity of the generated SiO2 layer. A uniform surface coating on the PVDF upper layer resulted from the presence of micrometre and nanometre-sized roughness on the surface of the PVDF membrane, which was achieved with a SiO2 concentration of 4.44 mg ml−1 (0.2 g/45 ml) in the coating solution. As a result, the water contact angle of the modified surface was recorded as 155 ± 3°, which is higher than that of the pristine surface. The high contact angle is advantageous for reducing the wetting of the membrane. Additional mass transfer resistance was introduced by the superhydrophobic layer. In addition, continuous CO2 absorption tests were carried out in original and modified PVDF hollow fibre membrane contactors, using monoethanolamine (MEA) solution as the absorbent. A long-term stability test revealed that the modified PVDF hollow fibre membrane contactor was able to outperform the original membrane contactor and demonstrated outstanding long-term stability, suggesting that spray deposition is a promising approach to obtain superhydrophobic PVDF membranes for liquid–gas membrane absorption. PMID:29291117

Alterations of the outer retina in non-arteritic anterior ischaemic optic neuropathy detected using spectral-domain optical coherence tomography.

PubMed

Ackermann, Philipp; Brachert, Maike; Albrecht, Philipp; Ringelstein, Marius; Finis, David; Geerling, Gerd; Aktas, Orhan; Guthoff, Rainer

2017-07-01

A characteristic disease pattern may be reflected by retinal layer thickness changes in non-arteritic anterior ischaemic optic neuropathy measured using spectraldomain optical coherence tomography. Retinal layer segmentation is enabled by advanced software. In this study, retinal layer thicknesses in acute and chronic non-arteritic anterior ischaemic optic neuropathy were compared. A single-centre cross-sectional analysis was used. A total of 27 patients (20 age-matched healthy eyes) were included: 14 with acute (<7 days) and 13 patients with chronic non-arteritic anterior ischaemic optic neuropathy. Macular volume and 12° peripapillary ring optical coherence tomography scans were used. The peripapillary thicknesses of the following layers were determined by manual segmentation: retinal nerve fibres, ganglion cells + inner plexiform layer, inner nuclear layer + outer plexiform layer, outer nuclear layer + inner segments of the photoreceptors and outer segments of the photoreceptors to Bruch's membrane. Macular retinal layer thicknesses were automatically determined in volume cubes centred on the fovea. Peripapillary retinal swelling in acute nonarteritic anterior ischaemic optic neuropathy was attributable to retinal nerve fibre layer, ganglion cell layer/inner plexiform layer and outer nuclear layer/segments of the photoreceptors thickening. In chronic cases, peripapillary retinal nerve fibre layer, macular ganglion cell layer and inner plexiform layer thinning were observed. In acute non-arteritic anterior ischaemic optic neuropathy, the inner and outer peripapillary retinal layers are affected by thickness changes. In chronic cases, atrophy of the ganglion cells and their axons and dendrites is evident by inner retinal layer thinning. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Ventricular myoarchitecture in tetralogy of Fallot.

PubMed Central

Sanchez-Quintana, D.; Anderson, R. H.; Ho, S. Y.

1996-01-01

BACKGROUND: Little attention has been paid to the architecture of the muscle fibres of the ventricular walls in congenitally malformed hearts. In this study the gross pattern of myocardial fibres in normal hearts was compared with that in cases of tetralogy of Fallot. METHODS AND RESULTS: After morphological examination nine specimens with tetralogy were dissected to study the ventricular myoarchitecture. Changes were found in the shape of the malformed ventricles. The ventricular walls were arranged in layers in all hearts. Superficial and deep layers were present in both ventricles, with the superficial layer showing a more oblique orientation in the specimens with tetralogy than in normal hearts. Modifications of muscle fibre that were related to the type of malformation were seen in the deep layer. A middle layer was present in the left ventricles of normal hearts and specimens with tetralogy: this showed a horizontal orientation in both groups. In contrast, a middle layer was found in the right ventricle only in specimens showing tetralogy. CONCLUSIONS: The malformed hearts showed modifications in ventricular shape, in the arrangement of muscle in the right ventricle, and in the overall myoarchitecture. These changes could well be the consequence of the same agent (or agents) that caused the structural defect. Images PMID:8868990

High-Resolution Fibre-Optic Temperature Sensing: A New Tool to Study the Two-Dimensional Structure of Atmospheric Surface-Layer Flow

NASA Astrophysics Data System (ADS)

Thomas, Christoph K.; Kennedy, Adam M.; Selker, John S.; Moretti, Ayla; Schroth, Martin H.; Smoot, Alexander R.; Tufillaro, Nicholas B.; Zeeman, Matthias J.

2012-02-01

We present a novel approach based on fibre-optic distributed temperature sensing (DTS) to measure the two-dimensional thermal structure of the surface layer at high resolution (0.25 m, ≈0.5 Hz). Air temperature observations obtained from a vertically-oriented fibre-optics array of approximate dimensions 8 m × 8 m and sonic anemometer data from two levels were collected over a short grass field located in the flat bottom of a wide valley with moderate surface heterogeneity. The objectives of the study were to evaluate the potential of the DTS technique to study small-scale processes in the surface layer over a wide range of atmospheric stability, and to analyze the space-time dynamics of transient cold-air pools in the calm boundary layer. The time response and precision of the fibre-based temperatures were adequate to resolve individual sub-metre sized turbulent and non-turbulent structures, of time scales of seconds, in the convective, neutral, and stable surface layer. Meaningful sensible heat fluxes were computed using the eddy-covariance technique when combined with vertical wind observations. We present a framework that determines the optimal environmental conditions for applying the fibre-optics technique in the surface layer and identifies areas for potentially significant improvements of the DTS performance. The top of the transient cold-air pool was highly non-stationary indicating a superposition of perturbations of different time and length scales. Vertical eddy scales in the strongly stratified transient cold-air pool derived from the DTS data agreed well with the buoyancy length scale computed using the vertical velocity variance and the Brunt-Vaisala frequency, while scales for weak stratification disagreed. The high-resolution DTS technique opens a new window into spatially sampling geophysical fluid flows including turbulent energy exchange.

Improving Structural and Functional Agreement in Patients with Glaucoma by Using Customized Perimetric Locations and Images of the Retinal Nerve Fiber Bundles

NASA Astrophysics Data System (ADS)

Alluwimi, Muhammed Saad

Glaucoma is the second leading cause of the blindness worldwide. It is a group of chronic, progressive, and potentially blinding optic neuropathies characterized by abnormalities of the optic nerve head and/or retinal nerve fiber layer (RNFL) associated with visual field abnormality. When diagnosing and managing patients with glaucoma, clinicians evaluate the agreement between structural and functional measures. However, it has been widely recognized that there is often a discordance between structural and functional (e.g., perimetry) measures in glaucoma, posing a challenge for clinicians to make their decisions. As explained in the literature, this discordance may relate to high normal between-subject variation, insufficient knowledge of the RNFL bundle organization, sparse spacing of the perimetric locations used to measure the functional performance of ganglion cells, high test-retest variation for the most commonly used stimulus for perimetry, and poor perimetric sampling of the macula. The aim of this thesis was to overcome this discordance by conducting three experiments: First, asymmetry analysis was used to reduce between-subject variation of the macular thickness and ganglion cell thickness measurements with OCT. This variation was decreased at particular regions of the macula. Outside the macula, the variation remained high leading to the second experiment in which customized closely-spaced perimetric locations were presented at wedge defects, guided by the OCT en face images of the RNFL bundles. A rapid suprathreshold perimetric strategy was used and perimetric defect was, in most cases, in correspondence with the structural defect. To threshold perimetric defects, an elongated blur-resistant stimulus was oriented within damaged RNFL bundles. It was found that contrast sensitivities were below the 95% normal limit in 37 of 44 locations. The latter experiment focused on wedge defects outside the macula, which led to the third experiment in which the goal was to investigate the feasibility of a basis to individualize perimetric locations within the macula guided by structural damage seen on OCT en face images. In preliminary data, it was feasible to individualize perimetric locations within the macula. In this thesis, the agreement between structural and functional measures was improved in glaucoma, by developing methods and techniques that provided a framework to help overcome challenges in clinical decision making.

Novel Bruch's Membrane Opening Minimum Rim Area Equalizes Disc Size Dependency and Offers High Diagnostic Power for Glaucoma.

PubMed

Enders, Philip; Adler, Werner; Schaub, Friederike; Hermann, Manuel M; Dietlein, Thomas; Cursiefen, Claus; Heindl, Ludwig M

2016-12-01

The purpose of this study was to assess the diagnostic power of the novel two-dimensional parameter Bruch's membrane opening minimal rim area (BMO-MRA) in spectral-domain optical coherence tomography (SD-OCT) for detection of glaucoma compared to minimal rim width (BMO-MRW) and retinal nerve fiber layer (RNFL) thickness in large and small optic discs. In this case-control, cross-sectional study, 207 eyes of 207 participants, including 89 controls and 97 patients with glaucoma and 21 with ocular hypertension (OHT), with a disc size <1.63 mm2 or >2.43 mm2 underwent SD-OCT, confocal laser scanning tomography (CSLT), visual field testing, and clinical examination. Bruch's membrane opening-MRA BMO-MRW, RNFL thickness of SD-OCT and disc margin rim area (DM-RA) of CSLT were evaluated and analyzed for diagnostic power to detect glaucoma. In healthy eyes with macrodiscs, mean BMO-MRW of 243.14 ± 43.12 μm was significantly smaller than BMO-MRW in microdiscs (338.97 ± 69.39; P < 0.001). Bruch's membrane opening-MRA was comparable between disc size groups with 1.22 ± 0.25 mm2 for macrodiscs and 1.26 ± 0.27 mm2 for microdiscs (P = 0.51), as was RNFL thickness (82.69 ± 15.76 μm versus 78.53 ± 11.01 μm, respectively; P = 0.28). Perimetric mean deviation was -8.7 ± 6.3 dB in glaucoma and -0.6 ± 1.60 dB in OHT patients. Correlation of BMO-MRA and visual field function was rho (ρ) = 0.70 (P < 0.001). Diagnostic power to differentiate glaucoma patients was highest for BMO-MRA. Partial area under the curve (pAUC) for BMO-MRA was 0.14 for specificity between 0.8 and 1.0, exceeding pAUCs of BMO-MRW (P < 0.001), RNFL thickness (P = 0.03), and DM-RA (P = 0.01). Bruch's membrane opening-based minimum rim area measurements offer advantages compared to one-dimensional parameters assessing neuroretinal rim by SD-OCT. In nonglaucomatous eyes, BMO-MRA values seem comparable for the full range of disc sizes. Bruch's membrane opening-MRA surpasses other parameters in diagnostic power for glaucoma.

Comparison study of OCT, HRT and VF findings among normal controls and patients with pseudoexfoliation, with or without increased IOP.

PubMed

Riga, Fryni; Georgalas, Ilias; Tsikripis, Panagiotis; Papaconstantinou, Dimitrios

2014-01-01

To compare and evaluate optic nerve head (ONH) and retinal nerve fiber layer (RNFL) measurements obtained with the optical coherence tomography (OCT) and the Heidelberg retina tomography (HRT) to visual field (VF) parameters in normal and in patients with pseudoexfoliation with or without increased intraocular pressure (IOP). A total of 96 subjects were included in our study aged between 65 years and 78 years. The normal group consisted of 28 subjects (14 men and 14 women). Out of the total number of patients, 68 patients who showed pseudoexfoliation (21 men and 47 women) were divided into two groups. Of these, the first group had pseudoexfoliation with increased IOP and the second group showed deposits of pseudoexfoliative material without an increase in IOP. The normal controls were randomly chosen and restricted to those without any glaucomatous optic disc damages, VF defects, and an IOP <15 mmHg. All subjects were prospectively included for repeated measurements of IOP, OCT, HRT, and VFs during the same visit by the same examiner and all measurements were repeated every 3 months. Mean RNFL thickness measured by OCT was larger in the normal controls than in the other two groups (98.04 μm (first group) vs 75.42 μm and 97.02 μm (second group), P<0.05). Four-quadrant RNFL thickness measurements were significantly different between the normal and the group 1 (P<0.05) but not with the group 2 (P>0.05). Rim area had a mean difference of -0.44, whereas cup-to-disc ratio (C/D) showed a mean difference of 0.31, thus being significantly different between the normal and the two groups (all P<0.05). The median of the mean deviation parameter of VFs was -0.28 for the normal vs -0.32 and -0.18 for the other two groups, whereas pattern standard deviation median difference was 0.89 for the normal and 1.32 and 1.20 for the other two groups, respectively (P<0.05). Both OCT and HRT showed early ONH and RNFL changes in their parameters and did not correlate with the normal findings of the automated perimetry.

Comparison study of OCT, HRT and VF findings among normal controls and patients with pseudoexfoliation, with or without increased IOP

PubMed Central

Riga, Fryni; Georgalas, Ilias; Tsikripis, Panagiotis; Papaconstantinou, Dimitrios

2014-01-01

Purpose To compare and evaluate optic nerve head (ONH) and retinal nerve fiber layer (RNFL) measurements obtained with the optical coherence tomography (OCT) and the Heidelberg retina tomography (HRT) to visual field (VF) parameters in normal and in patients with pseudoexfoliation with or without increased intraocular pressure (IOP). Methods A total of 96 subjects were included in our study aged between 65 years and 78 years. The normal group consisted of 28 subjects (14 men and 14 women). Out of the total number of patients, 68 patients who showed pseudoexfoliation (21 men and 47 women) were divided into two groups. Of these, the first group had pseudoexfoliation with increased IOP and the second group showed deposits of pseudoexfoliative material without an increase in IOP. The normal controls were randomly chosen and restricted to those without any glaucomatous optic disc damages, VF defects, and an IOP <15 mmHg. All subjects were prospectively included for repeated measurements of IOP, OCT, HRT, and VFs during the same visit by the same examiner and all measurements were repeated every 3 months. Results Mean RNFL thickness measured by OCT was larger in the normal controls than in the other two groups (98.04 μm (first group) vs 75.42 μm and 97.02 μm (second group), P<0.05). Four-quadrant RNFL thickness measurements were significantly different between the normal and the group 1 (P<0.05) but not with the group 2 (P>0.05). Rim area had a mean difference of −0.44, whereas cup-to-disc ratio (C/D) showed a mean difference of 0.31, thus being significantly different between the normal and the two groups (all P<0.05). The median of the mean deviation parameter of VFs was −0.28 for the normal vs −0.32 and −0.18 for the other two groups, whereas pattern standard deviation median difference was 0.89 for the normal and 1.32 and 1.20 for the other two groups, respectively (P<0.05). Conclusion Both OCT and HRT showed early ONH and RNFL changes in their parameters and did not correlate with the normal findings of the automated perimetry. PMID:25506206

Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance

NASA Astrophysics Data System (ADS)

Senokos, E.; Reguero, V.; Palma, J.; Vilatela, J. J.; Marcilla, Rebeca

2016-02-01

In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m2 g-1, high electrical conductivity (3.5 × 105 S m-1) and mechanical properties in the high-performance range including toughness (35 J g-1) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg-1 and 14 Wh kg-1, respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10 000 cycles of charge-discharge at 3.5 V.In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m2 g-1, high electrical conductivity (3.5 × 105 S m-1) and mechanical properties in the high-performance range including toughness (35 J g-1) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg-1 and 14 Wh kg-1, respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10 000 cycles of charge-discharge at 3.5 V. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07697h

Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance.

PubMed

Senokos, E; Reguero, V; Palma, J; Vilatela, J J; Marcilla, Rebeca

2016-02-14

In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m(2) g(-1), high electrical conductivity (3.5 × 10(5) S m(-1)) and mechanical properties in the high-performance range including toughness (35 J g(-1)) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg(-1) and 14 Wh kg(-1), respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10,000 cycles of charge-discharge at 3.5 V.

Microscopic anatomy of the visceral fasciae.

PubMed

Stecco, Carla; Sfriso, Maria Martina; Porzionato, Andrea; Rambaldo, Anna; Albertin, Giovanna; Macchi, Veronica; De Caro, Raffaele

2017-07-01

The term 'visceral fascia' is a general term used to describe the fascia lying immediately beneath the mesothelium of the serosa, together with that immediately surrounding the viscera, but there are many types of visceral fasciae. The aim of this paper was to identify the features they have in common and their specialisations. The visceral fascia of the abdomen (corresponding to the connective tissue lying immediately beneath the mesothelium of the parietal peritoneum), thorax (corresponding to the connective tissue lying immediately beneath the mesothelium of the parietal pleura), lung (corresponding to the connective tissue under the mesothelium of the visceral pleura), liver (corresponding to the connective tissue under the mesothelium of the visceral peritoneum), kidney (corresponding to the Gerota fascia), the oesophagus (corresponding to its adventitia) and heart (corresponding to the fibrous layer of the pericardial sac) from eight fresh cadavers were sampled and analysed with histological and immunohistochemical stains to evaluate collagen and elastic components and innervation. Although the visceral fasciae make up a well-defined layer of connective tissue, the thickness, percentage of elastic fibres and innervation vary among the different viscera. In particular, the fascia of the lung has a mean thickness of 134 μm (± 21), that of heart 792 μm (± 132), oesophagus 105 μm (± 10), liver 131 μm (± 18), Gerota fascia 1009 μm (± 105) and the visceral fascia of the abdomen 987 μm (± 90). The greatest number of elastic fibres (9.79%) was found in the adventitia of the oesophagus. The connective layers lying immediately outside the mesothelium of the pleura and peritoneum also have many elastic fibres (4.98% and 4.52%, respectively), whereas the pericardium and Gerota fascia have few (0.27% and 1.38%). In the pleura, peritoneum and adventitia of the oesophagus, elastic fibres form a well-defined layer, corresponding to the elastic lamina, while in the other cases they are thinner and scattered in the connective tissue. Collagen fibres also show precise spatial organisation, being arranged in several layers. In each layer, all the fibrous bundles are parallel with each other, but change direction among layers. Loose connective tissue rich in elastic fibres is found between contiguous fibrous layers. Unmyelinated nerve fibres were found in all samples, but myelinated fibres were only found in some fasciae, such as those of the liver and heart, and the visceral fascia of the abdomen. According to these findings, we propose distinguishing the visceral fasciae into two large groups. The first group includes all the fasciae closely related to the individual organ and giving shape to it, supporting the parenchyma; these are thin, elastic and very well innervated. The second group comprises all the fibrous sheets forming the compartments for the organs and also connecting the internal organs to the musculoskeletal system. These fasciae are thick, less elastic and less innervated, but they contain larger and myelinated nerves. We propose to call the first type of fasciae 'investing fasciae', and the second type 'insertional fasciae'. © 2017 Anatomical Society.

Analysis of the Origin of Atypical Scanning Laser Polarimetry Patterns by Polarization-Sensitive Optical Coherence Tomography

PubMed Central

Götzinger, Erich; Pircher, Michael; Baumann, Bernhard; Hirn, Cornelia; Vass, Clemens; Hitzenberger, Christoph K.

2010-01-01

Purpose To analyze the physical origin of atypical scanning laser polarimetry (SLP) patterns. To compare polarization-sensitive optical coherence tomography (PS-OCT) scans to SLP images. To present a method to obtain pseudo-SLP images by PS-OCT that are free of atypical artifacts. Methods Forty-one eyes of healthy subjects, subjects with suspected glaucoma, and patients with glaucoma were imaged by SLP (GDx VCC) and a prototype spectral domain PS-OCT system. The PS-OCT system acquires three-dimensional (3D) datasets of intensity, retardation, and optic axis orientation simultaneously within 3 seconds. B-scans of intensity and retardation and en face maps of retinal nerve fiber layer (RNFL) retardation were derived from the 3D PS-OCT datasets. Results were compared with those obtained by SLP. Results Twenty-two eyes showed atypical retardation patterns, and 19 eyes showed normal patterns. From the 22 atypical eyes, 15 showed atypical patterns in both imaging modalities, five were atypical only in SLP images, and two were atypical only in PS-OCT images. In most (15 of 22) atypical cases, an increased penetration of the probing beam into the birefringent sclera was identified as the source of atypical patterns. In such cases, the artifacts could be eliminated in PS-OCT images by depth segmentation and exclusion of scleral signals. Conclusions PS-OCT provides deeper insight into the contribution of different fundus layers to SLP images. Increased light penetration into the sclera can distort SLP retardation patterns of the RNFL. PMID:19036999

Comparison of macular OCTs in right and left eyes of normal people

NASA Astrophysics Data System (ADS)

Mahmudi, Tahereh; Kafieh, Rahele; Rabbani, Hossein; Mehri dehnavi, Alireza; Akhlagi, Mohammadreza

2014-03-01

Retinal 3D Optical coherence tomography (OCT) is a non-invasive imaging modality in ocular diseases. Due to large volumes of OCT data, it is better to utilize automatic extraction of information from OCT images, such as total retinal thickness and retinal nerve fiber layer thickness (RNFLT). These two thickness values have become useful indices to indicate the progress of diseases like glaucoma, according to the asymmetry between two eyes of an individual. Furthermore, the loss of ganglion cells may not be diagnosable by other tests and even not be evaluated when we only consider the thickness of one eye (due to dramatic different thickness among individuals). This can justify our need to have a comparison between thicknesses of two eyes in symmetricity. Therefore, we have proposed an asymmetry analysis of the retinal nerve layer thickness and total retinal thickness around the macula in the normal Iranian population. In the first step retinal borders are segmented by diffusion map method and thickness profiles were made. Then we found the middle point of the macula by pattern matching scheme. RNFLT and retinal thickness are analyzed in 9 sectors and the mean and standard deviation of each sector in the right and left eye are obtained. The maximums of the average RNFL thickness in right and left eyes are seen in the perifoveal nasal, and the minimums are seen in the fovea. Tolerance limits in RNFL thickness is shown to be between 0.78 to 2.4 μm for 19 volunteers used in this study.

Retinal nerve fiber layer thickness map and blood flow pulsation measured with SDOCT

NASA Astrophysics Data System (ADS)

Mujat, Mircea; Chan, Raymond C.; Cense, Barry; Pierce, Mark; Park, Hyle; Joo, Chulmin; Chen, Teresa C.; de Boer, Johannes F.

2006-02-01

Spectral-Domain Optical Coherence Tomography (SDOCT) allows for in-vivo video-rate investigation of biomedical tissue depth structure intended for non-invasive optical diagnostics. It has been suggested that OCT can be used for di-agnosis of glaucoma by measuring the thickness of the Retinal Nerve Fiber Layer (RNLF). We present an automated method for determining the RNFL thickness from a 3-D dataset based on edge detection using a deformable spline algo-rithm. The RNFL thickness map is combined with an integrated reflectance map and retinal cross-sectional images to provide the ophthalmologist with a familiar image for interpreting the OCT data. The video-rate capabilities of our SDOCT system allow for mapping the true retinal topography since motion artifacts are significantly reduced as com-pared to slower time-domain systems. Combined with Doppler Velocimetry, SDOCT also provides information on retinal blood flow dynamics. We analyzed the pulsatile nature of the bidirectional flow dynamics in an artery-vein pair for a healthy volunteer at different locations and for different blood vessel diameters. The Doppler phase shift is determined as the phase difference at the same point of adjacent depth profiles, and is integrated over the area delimited by two circles corresponding to the blood vessels location. Its temporal evolution clearly shows the blood flow pulsatile nature, the cardiac cycle, in both artery and vein. The artery is identified as having a stronger variation of the integrated phase shift. We observe that artery pulsation is always easily detectable, while vein pulsation seems to depend on the veins diameter.

Functional gradients in the pericarp of the green coconut inspire asymmetric fibre-composites with improved impact strength, and preserved flexural and tensile properties.

PubMed

Graupner, Nina; Labonte, David; Humburg, Heide; Buzkan, Tayfun; Dörgens, Anna; Kelterer, Wiebke; Müssig, Jörg

2017-02-28

Here we investigate the mechanical properties and structural design of the pericarp of the green coconut (Cocos nucifera L.). The pericarp showed excellent impact characteristics, and mechanical tests of its individual components revealed gradients in stiffness, strength and elongation at break from the outer to the inner layer of the pericarp. In order to understand more about the potential effect of such gradients on 'bulk' material properties, we designed simple, graded, cellulose fibre-reinforced polylactide (PLA) composites by stacking layers reinforced with fibres of different mechanical properties. Tensile properties of the graded composites were largely determined by the 'weakest' fibre, irrespective of the fibre distribution. However, a graded design led to pronounced asymmetric bending and impact properties. Bio-inspired, asymmetrically graded composites showed a flexural strength and modulus comparable to that of the strongest reference samples, but the elongation at maximum load was dependent on the specimen orientation. The impact strength of the graded composites showed a similar orientation-dependence, and peak values exceeded the impact strength of a non-graded reference composite containing identical fibre fractions by up to a factor of three. In combination, our results show that an asymmetric, systematic variation of fibre properties can successfully combine desirable properties of different fibre types, suggesting new routes for the development of high-performance composites, and improving our understanding of the structure-function relationship of the coconut pericarp.

Deep Retinal Layer Microvasculature Dropout detected by the Optical Coherence Tomography Angiography in Glaucoma

PubMed Central

Suh, Min Hee; Zangwill, Linda M.; Manalastas, Patricia Isabel C.; Belghith, Akram; Yarmohammadi, Adeleh; Medeiros, Felipe A.; Diniz-Filho, Alberto; Saunders, Luke J.; Weinreb, Robert N.

2016-01-01

Purpose To investigate factors associated with dropout of the deep retinal layer microvasculature within the β-zone parapapillary atrophy (βPPA) assessed by optical coherence tomography angiography (OCT-A) in glaucomatous eyes. Design Cross-sectional study. Participants Seventy-one eyes from 71 primary open angle glaucoma (POAG) patients with βPPA enrolled in the Diagnostic Innovations in Glaucoma Study. Methods βPPA deep layer microvasculature dropout was defined as a complete loss of the microvasculature located within deep retinal layer of the βPPA from OCT-A-derived optic nerve head vessel density maps by standardized qualitative assessment. Circumpapillary vessel density (cpVD) within the retinal nerve fiber layer (RNFL) was also calculated using OCT-A. Choroidal thickness and presence of the focal lamina cribrosa (LC) defect were determined using swept-source OCT. Main Outcome Measures Presence of the βPPA deep layer microvasculature dropout. Parameters including age, systolic and diastolic blood pressure, axial length, intraocular pressure, disc hemorrhage, cpVD, visual field (VF) mean deviation (MD), focal LC defect, βPPA area, and choroidal thickness were analyzed. Results βPPA deep layer microvasculature dropout was detected in 37 eyes (52.1%) of eyes with POAG. Eyes with dropouts had a higher prevalence of LC defect (70.3 vs. 32.4%), lower cpVD (52.7 vs. 58.8%), worse VF MD (-9.06 vs. -3.83dB), thinner total choroidal thickness (126.5 vs. 169.1/μm), longer axial length (24.7 vs. 24.0mm), larger βPPA (1.2 vs. 0.76mm2) and lower diastolic blood pressure (74.7 vs. 81.7mmHg) than those without dropouts (P< 0.05, respectively). In the multivariate logistic regression, higher prevalence of focal LC defect (odds ratio [OR], 6.27; P = 0.012), reduced cpVD (OR, 1.27; P = 0.002), worse VF MD (OR, 1.27; P = 0.001), thinner choroidal thickness (OR, 1.02; P = 0.014), and lower diastolic blood pressure (OR, 1.16; P = 0.003) were significantly associated with the dropout. Conclusions Certain systemic and ocular factors such as focal LC defect, more advanced disease status, reduced RNFL vessel density, thinner choroidal thickness, and lower diastolic blood pressure were factors associated with the βPPA deep layer microvasculature dropout in glaucomatous eyes. Longitudinal studies are required to elucidate the temporal relationship between βPPA deep layer dropout and these factors. PMID:27769587

Deep Retinal Layer Microvasculature Dropout Detected by the Optical Coherence Tomography Angiography in Glaucoma.

PubMed

Suh, Min Hee; Zangwill, Linda M; Manalastas, Patricia Isabel C; Belghith, Akram; Yarmohammadi, Adeleh; Medeiros, Felipe A; Diniz-Filho, Alberto; Saunders, Luke J; Weinreb, Robert N

2016-12-01

To investigate factors associated with dropout of the parapapillary deep retinal layer microvasculature assessed by optical coherence tomography angiography (OCTA) in glaucomatous eyes. Cross-sectional study. Seventy-one eyes from 71 primary open-angle glaucoma (POAG) patients with β-zone parapapillary atrophy (βPPA) enrolled in the Diagnostic Innovations in Glaucoma Study. Parapapillary deep-layer microvasculature dropout was defined as a complete loss of the microvasculature located within the deep retinal layer of the βPPA from OCTA-derived optic nerve head vessel density maps by standardized qualitative assessment. Circumpapillary vessel density (cpVD) within the retinal nerve fiber layer (RNFL) also was calculated using OCTA. Choroidal thickness and presence of focal lamina cribrosa (LC) defects were determined using swept-source optical coherence tomography. Presence of parapapillary deep-layer microvasculature dropout. Parameters including age, systolic and diastolic blood pressure, axial length, intraocular pressure, disc hemorrhage, cpVD, visual field (VF) mean deviation (MD), focal LC defects βPPA area, and choroidal thickness were analyzed. Parapapillary deep-layer microvasculature dropout was detected in 37 POAG eyes (52.1%). Eyes with microvasculature dropout had a higher prevalence of LC defects (70.3% vs. 32.4%), lower cpVD (52.7% vs. 58.8%), worse VF MD (-9.06 dB vs. -3.83 dB), thinner total choroidal thickness (126.5 μm vs. 169.1 μm), longer axial length (24.7 mm vs. 24.0 mm), larger βPPA (1.2 mm 2 vs. 0.76 mm 2 ), and lower diastolic blood pressure (74.7 mmHg vs. 81.7 mmHg) than those without dropout (P < 0.05, respectively). In the multivariate logistic regression analysis, higher prevalence of focal LC defects (odds ratio [OR], 6.27; P = 0.012), reduced cpVD (OR, 1.27; P = 0.002), worse VF MD (OR, 1.27; P = 0.001), thinner choroidal thickness (OR, 1.02; P = 0.014), and lower diastolic blood pressure (OR, 1.16; P = 0.003) were associated significantly with the dropout. Systemic and ocular factors including focal LC defects more advanced glaucoma, reduced RNFL vessel density, thinner choroidal thickness, and lower diastolic blood pressure were factors associated with the parapapillary deep-layer microvasculature dropout in glaucomatous eyes. Longitudinal studies are required to elucidate the temporal relationship between parapapillary deep-layer microvasculature dropout and systemic and ocular factors. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Multi-layered sensor yarns for in situ monitoring of textile reinforced composites

NASA Astrophysics Data System (ADS)

Haentzsche, E.; Onggar, T.; Nocke, A.; Hund, R. D.; Cherif, Ch

2017-10-01

In this contribution, the characteristic of yarns that have intrinsically conductivity as well as such with coaxial conductive coatings acting as in situ strain sensors are described. The objective of the based research projects is the real-time in situ sensing of both global stresses acting on fibre reinforced plastic (FRP) components and the detection of resulted local microscopic damages due to creep, delamination and micro-cracks in the fibre-matrix interphase of glass fibre (GFRP) and carbon fibre (CFRP) composites. Sensor materials similar to the particular FRP and its mechanical behaviour have been chosen. In the first approach, GF- and aramid-based sensor yarns have been developed with multiple tailored silver layer coating system capable to distinguish multiple scaled damage mechanism due to these effects globally and locally. The second approach bases on the piezoresistive effect of CF rovings for their usage as in situ strain sensors. In the next step, suitable fibre and polymer film-based cleading have been tested and evaluated, granting sufficient electrical isolation to avoid shortcircuits between the conductive sensor layers itself or between the sensor and intrinsically conductive CFRP respectively. Initially, the sensor performance of global strain measurement, means the accumulated strain along the integration length of the sensor yarn, has been evaluated during tensile stressing of FRP with integrated suchlike functionalised sensor yarns.

Peptide-containing nerve fibres in the gut wall in Crohn's disease.

PubMed Central

Sjölund, K; Schaffalitzky, O B; Muckadell, D E; Fahrenkrug, J; Håkanson, R; Peterson, B G; Sundler, F

1983-01-01

Neurones containing VIP, substance P, or enkephalin were studied by immunocytochemistry in intestinal specimens from 27 patients with Crohn's disease. Also several endocrine cell systems in the gut were examined. The results were compared with those from a control group of 26 patients. The relative frequency of various endocrine cells did not differ overtly from that in controls. Vasoactive intestinal polypeptide and substance P nerve fibres were distributed in all layers of the gut wall, including the submucosal and myenteric plexuses, whereas enkephalin fibres were restricted to the smooth muscle layer and the myenteric plexus. The distribution and frequency of the peptide-containing nerve fibres were the same in Crohn's disease patients as in control patients. A proportion of these nerve fibres, however, were notably coarse in the Crohn's disease patients. This was particularly apparent in the afflicted parts of the intestine although it was noted also in non-afflicted parts. The concentration of VIP and substance P (expressed as pmol/g wet weight) did not, however, exceed that of the control group. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:6192043

High power operation of cladding pumped holmium-doped silica fibre lasers.

PubMed

Hemming, Alexander; Bennetts, Shayne; Simakov, Nikita; Davidson, Alan; Haub, John; Carter, Adrian

2013-02-25

We report the highest power operation of a resonantly cladding-pumped, holmium-doped silica fibre laser. The cladding pumped all-glass fibre utilises a fluorine doped glass layer to provide low loss cladding guidance of the 1.95 µm pump radiation. The operation of both single mode and large-mode area fibre lasers was demonstrated, with up to 140 W of output power achieved. A slope efficiency of 59% versus launched pump power was demonstrated. The free running emission was measured to be 2.12-2.15 µm demonstrating the potential of this architecture to address the long wavelength operation of silica based fibre lasers with high efficiency.

Moisture contamination detection in adhesive layer using embedded fibre Bragg grating sensors

NASA Astrophysics Data System (ADS)

Mieloszyk, Magdalena; Soman, Rohan; Bonilla Mora, Veronica; Ostachowicz, Wieslaw

2017-04-01

The paper presents an application of embedded fibre Bragg grating (FBG) sensors for moisture contamination detection in an adhesive layer between composite elements. Due to their high corrosion resistance as well as their small size and weight, FBG sensors are a great tool for Structural Health Monitoring of composite structures. Adhesive bonds are very popular in many industrial sectors (e.g. automotive, aerospace). One of the major problems limiting the use of adhesive joints is their sensitivity to moisture from its surroundings. Even 1% of moisture can negatively affect the adhesive bond layer. The experimental and numerical investigations were performed on two rectangular samples of two glass fibre reinforced composite elements bonded together using an adhesive commonly used in the bonding or repair of aircraft elements. Moisture contamination due to diffusion process changes the volumetric properties of the material induced strain. This strain was measured by FBG sensors embedded in the adhesive layer parallel to the main axis of the sample. The behaviour of the adhesive layer in the analysed sample was also modelled using the finite element commercial code ABAQUS. Numerical and experimental results confirm the utility of FBG sensors for moisture detection in the adhesive layer even when the amount of moisture is around 2% of the sample weight.

Sound absorption of textile material using a microfibres resistive layer

NASA Astrophysics Data System (ADS)

Segura Alcaraz, M. P.; Bonet-Aracil, M.; Segura Alcaraz, J. G.; Montava Seguí, I.

2017-10-01

Acoustic comfort is a basic human need. One of the adverse effects of noise is its interference with speech discrimination. Textile materials are suitable to be used as sound absorptive materials and thus help to improve acoustic comfort in rooms. Micro-fibre fabrics can be considered as better sound absorbers than regular fibre fabrics mainly due to the higher surface of its fibres and bigger contact area with the air thus, allowing greater dissipation of sound energy. In this work, the use of a microfibre woven fabric as an upstream layer is analysed considering acoustic issues. Authors demonstrate it improves the sound absorption of a polyester nonwoven, resulting in a material suitable for absorption at the sound frequencies of the human voice.

Relation Between Macular Retinal Ganglion Cell/Inner Plexiform Layer Thickness and Multifocal Electroretinogram Measures in Experimental Glaucoma

PubMed Central

Luo, Xunda; Patel, Nimesh B.; Rajagopalan, Lakshmi P.; Harwerth, Ronald S.; Frishman, Laura J.

2014-01-01

Purpose. We investigated relations between macular retinal ganglion cell plus inner plexiform layer (RGC+IPL) thickness and macular retinal function revealed by multifocal electroretinonography (mfERG) in a nonhuman primate model of experimental glaucoma. Methods. Retinal ganglion cell (RGC) structure and function were followed with spectral-domain optical coherence tomography (SD-OCT) and ERGs in five macaques with unilateral experimental glaucoma. Linear regression was used to study correlations in control (Con) and experimental (Exp) eyes between peripapillary retinal nerve fiber layer (RNFL) thickness, macular RGC+IPL thickness, multifocal photopic negative response (mfPhNR) and high-frequency multifocal oscillatory potentials (mfOP) in slow-sequence mfERG, and low-frequency component (mfLFC) in global-flash mfERG. We used ANOVA and paired t-tests to compare glaucoma-related mfERG changes between superior and inferior hemifields, foveal hexagon, inner three rings, and four quadrants of macula. Results. Average macular RGC+IPL and temporal RNFL thickness were strongly correlated (r2 = 0.90, P < 0.001). In hexagon-by-hexagon analysis, all three mfERG measures were correlated (P < 0.001) with RGC+IPL thickness for Con (r2, 0.33–0.51) and Exp eyes (r2, 0.17–0.35). The RGC structural and functional metrics decreased as eccentricity increased. The reduction in amplitude of mfERG measures in Exp eyes relative to Con eyes was proportionally greater, in general, than the relative thinning of RGC+IPL at the same location for eyes in which structural loss was not evident, or mild to moderate. Although not statistically significant, percent amplitude reduction of mfERG measures was greatest in the inferior temporal quadrant. Conclusions. Macular RGC+IPL thickness and mfERG measures of RGC function can be complementary tools in assessing glaucomatous neuropathy. PMID:24970256

Macular retinal and choroidal thickness in unilateral amblyopia using swept-source optical coherence tomography.

PubMed

Araki, Syunsuke; Miki, Atsushi; Goto, Katsutoshi; Yamashita, Tsutomu; Takizawa, Go; Haruishi, Kazuko; Ieki, Yoshiaki; Kiryu, Junichi; Yaoeda, Kiyoshi

2017-09-15

To investigate macular retinal and choroidal thickness in amblyopic eyes compared to that in fellow and normal eyes using swept-source optical coherence tomography (SS-OCT). This study examined 31 patients with hyperopic anisometropic amblyopia (6.9 ± 3.8 years, mean ± standard deviation), 15 patients with strabismic amblyopia without anisometropia (7.9 ± 4.2 years), and 24 age-matched controls (7.8 ± 3.3 years). Retinal and choroidal thickness was measured by 3D scans using SS-OCT. A 6-mm area around the fovea was automatically analyzed using the Early Treatment Diabetic Retinopathy Study map. The thickness from SS-OCT was corrected for magnification error using individual axial length, spherical refraction, cylinder refraction, and corneal radius. Retinal thickness was divided into the macular retinal nerve fiber layer (mRNFL), ganglion cell layer + inner plexiform layer (GCL+IPL), ganglion cell complex (GCC), and the inner limiting membrane to the retinal pigment epithelium (ILM-RPE) thickness. Retinal and choroidal thickness was compared among amblyopic, fellow, and normal eyes. In both amblyopia groups, there was no significant difference in the mRNFL, GCL+IPL, and GCC thicknesses among the amblyopic, fellow, and control eyes. In the anisometropic amblyopia group, choroidal thickness (subfovea, center 1 mm, nasal and inferior of the inner ring, nasal of the outer ring, and center 6 mm) of amblyopic eyes were significantly greater than that of fellow and normal eyes. In contrast, none of the choroidal thicknesses were significantly different among the investigated eyes in the strabismic amblyopia group. We found no significant difference in inner retinal thickness in patients with unilateral amblyopia. Although there were significant differences in choroidal thickness with hyperopic anisometropic amblyopia, there was no significant difference for the strabismic amblyopia. The discrepancy in choroidal thickness between the two types of amblyopia may be due to both differences in ocular size and underlying mechanism.

In vivo thickness and birefringence determination of the human retinal nerve fiber layer using polarization-sensitive optical coherence tomography.

PubMed

Cense, B; Chen, T C; de Boer, J F

2006-01-01

Thinning of the retinal nerve fiber layer and changes in retinal nerve fiber layer birefringence may both precede clinically detectable glaucomatous vision loss. We present in vivo thickness and depth-resolved birefringence measurements of the human retinal nerve fiber layer (RNFL) by use of polarization-sensitive optical coherence tomography (PS-OCT). Using a fiber-based PS-OCT setup real-time images of the human retina in vivo were recorded, co-registered with retinal video images of the location of PS-OCT scans. PS-OCT scans around the optic nerve head (ONH) of two healthy young volunteers were made using 10 concentric circles of increasing radius. Both the mean retinal nerve fiber layer thickness and mean retinal nerve fiber birefringence for each of 48 sectors on a circle were determined. The retinal nerve fiber layer thickness and birefringence varied as a function of sector around the ONH. Measured double pass phase retardation per unit depth values around the ONH range between 0.10 and 0.35 degrees/microm. The retinal nerve fiber layer becomes thinner with increasing distance from the ONH. In contrast, the birefringence does not vary significantly with increasing distance from the ONH.

[Glaucoma and optic nerve drusen: Limitations of optic nerve head OCT].

PubMed

Poli, M; Colange, J; Goutagny, B; Sellem, E

2017-09-01

Optic nerve head drusen are congenital calcium deposits located in the prelaminar section of the optic nerve head. Their association with visual field defects has been classically described, but the diagnosis of glaucoma is not easy in these cases of altered optic nerve head anatomy. We describe the case of a 67-year-old man with optic nerve head drusen complicated by glaucoma, which was confirmed by visual field and OCT examination of the peripapillary retinal nerve fiber layer (RNFL), but the measurement of the minimum distance between the Bruch membrane opening and the internal limiting membrane (minimum rim width, BMO-MRW) by OCT was normal. OCT of the BMO-MRW is a new diagnostic tool for glaucoma. Superficial optic nerve head drusen, which are found between the internal limiting membrane and the Bruch's membrane opening, overestimate the value of this parameter. BMO-MRW measurement is not adapted to cases of optic nerve head drusen and can cause false-negative results for this parameter, and the diagnosis of glaucoma in this case should be based on other parameters such as the presence of a fascicular defect in the retinal nerve fibers, RNFL or macular ganglion cell complex thinning, as well as visual field data. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

[A rare cause of optic neuropathy: Cassava].

PubMed

Zeboulon, P; Vignal-Clermont, C; Baudouin, C; Labbé, A

2016-06-01

Cassava root is a staple food for almost 500 million people worldwide. Excessive consumption of it is a rare cause of optic neuropathy. Ten patients diagnosed with cassava root related optic neuropathy were included in this retrospective study. Diagnostic criteria were a bilateral optic neuropathy preceded by significant cassava root consumption. Differential diagnoses were excluded through a neuro-ophthalmic examination, blood tests and a brain MRI. All patients had visual field examination and OCT retinal nerve fiber layer (RNFL) analysis as well as an evaluation of their cassava consumption. All patients had a bilateral optic nerve head atrophy or pallor predominantly located into the temporal sector. Visual field defects consisted of a central or cecocentral scotoma for all patients. RNFL showed lower values only in the temporal sector. Mean duration of cassava consumption prior to the appearance of visual symptoms was 22.7±11.2 years with a mean of 2.57±0.53 cassava-based meals per week. Cassava related optic neuropathy is possibly due to its high cyanide content and enabled by a specific amino-acid deficiency. Cassava root chronic consumption is a rare, underappreciated cause of optic neuropathy and its exact mechanism is still uncertain. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Glaucoma and its association with obstructive sleep apnea: A narrative review

PubMed Central

Chaitanya, Aditya; Pai, Vijaya H.; Mohapatra, Aswini Kumar; Ve, Ramesh S.

2016-01-01

Obstructive sleep apnea (OSA) is one of the systemic risk factors for glaucoma which causes irreversible visual field (VF) damage. We reviewed the published data of all types of studies on the association between these two conditions and papers regarding functional and structural changes related to glaucomatous damage using Scopus, web of science, and PubMed databases. There is evidence that the prevalence of glaucoma is higher in OSA patients, which independent of intraocular pressure (IOP). Studies have reported thinning of retinal nerve fiber layer (RNFL), alteration of optic nerve head, choroidal and macular thickness, and reduced VF sensitivity in patients of OSA with no history glaucoma. A negative correlation of apnea-hypopnea index with RNFL and VF indices has been described in some studies. Raised IOP was noted which is possibly related to obesity, supine position during sleep, and raised intracranial pressure. Diurnal fluctuations of IOP show more variations in OSA patients before and after continuous positive airway pressure (CPAP) therapy when compared with the normal cases. The vascular factors behind the pathogenesis include recurrent hypoxia with increased vascular resistance, oxidative stress damage to the optic nerve. In conclusion, comprehensive glaucoma evaluation should be recommended in patients with OSA and should also periodically monitor IOP during CPAP treatment which may trigger the progression of glaucomatous damage. PMID:27843225

Predictive Factors for Visual Field Conversion: Comparison of Scanning Laser Polarimetry and Optical Coherence Tomography.

PubMed

Diekmann, Theresa; Schrems-Hoesl, Laura M; Mardin, Christian Y; Laemmer, Robert; Horn, Folkert K; Kruse, Friedrich E; Schrems, Wolfgang A

2018-02-01

The purpose of this study was to compare the ability of scanning laser polarimetry (SLP) and spectral-domain optical coherence tomography (SD-OCT) to predict future visual field conversion of subjects with ocular hypertension and early glaucoma. All patients were recruited from the Erlangen glaucoma registry and examined using standard automated perimetry, 24-hour intraocular pressure profile, and optic disc photography. Peripapillary retinal nerve fiber layer thickness (RNFL) measurements were obtained by SLP (GDx-VCC) and SD-OCT (Spectralis OCT). Positive and negative predictive values (PPV, NPV) were calculated for morphologic parameters of SLP and SD-OCT. Kaplan-Meier survival curves were plotted and log-rank tests were performed to compare the survival distributions. Contingency tables and Venn-diagrams were calculated to compare the predictive ability. The study included 207 patients-75 with ocular hypertension, 85 with early glaucoma, and 47 controls. Median follow-up was 4.5 years. A total of 29 patients (14.0%) developed visual field conversion during follow-up. SLP temporal-inferior RNFL [0.667; 95% confidence interval (CI), 0.281-0.935] and SD-OCT temporal-inferior RNFL (0.571; 95% CI, 0.317-0.802) achieved the highest PPV; nerve fiber indicator (0.923; 95% CI, 0.876-0.957) and SD-OCT mean (0.898; 95% CI, 0.847-0.937) achieved the highest NPV of all investigated parameters. The Kaplan-Meier curves confirmed significantly higher survival for subjects within normal limits of measurements of both devices (P<0.001). Venn diagrams tested with McNemar test statistics showed no significant difference for PPV (P=0.219) or NPV (P=0.678). Both GDx-VCC and SD-OCT demonstrate comparable results in predicting future visual field conversion if taking typical scans for GDx-VCC. In addition, the likelihood ratios suggest that GDx-VCC's nerve fiber indicator<30 may be the most useful parameter to confirm future nonconversion. (http://www.ClinicalTrials.gov number, NTC00494923; Erlangen Glaucoma Registry).

Optical coherence tomography for glaucoma diagnosis: An evidence based meta-analysis

PubMed Central

Armstrong, James J.; Pintwala, Robert; Hutnik, Cindy

2018-01-01

Purpose Early detection, monitoring and understanding of changes in the retina are central to the diagnosis of glaucomatous optic neuropathy, and vital to reduce visual loss from this progressive condition. The main objective of this investigation was to compare glaucoma diagnostic accuracy of commercially available optical coherence tomography (OCT) devices (Zeiss Stratus, Zeiss Cirrus, Heidelberg Spectralis and Optovue RTVue, and Topcon 3D-OCT). Patients 16,104 glaucomatous and 11,543 normal eyes reported in 150 studies. Methods Between Jan. 2017 and Feb 2017, MEDLINE®, EMBASE®, CINAHL®, Cochrane Library®, Web of Science®, and BIOSIS® were searched for studies assessing glaucoma diagnostic accuracy of the aforementioned OCT devices. Meta-analysis was performed pooling area under the receiver operating characteristic curve (AUROC) estimates for all devices, stratified by OCT type (RNFL, macula), and area imaged. Results 150 studies with 16,104 glaucomatous and 11,543 normal control eyes were included. Key findings: AUROC of glaucoma diagnosis for RNFL average for all glaucoma patients was 0.897 (0.887–0.906, n = 16,782 patient eyes), for macula ganglion cell complex (GCC) was 0.885 (0.869–0.901, n = 4841 eyes), for macula ganglion cell inner plexiform layer (GCIPL) was 0.858 (0.835–0.880, n = 4211 eyes), and for total macular thickness was 0.795 (0.754–0.834, n = 1063 eyes). Conclusion The classification capability was similar across all 5 OCT devices. More diagnostically favorable AUROCs were demonstrated in patients with increased glaucoma severity. Diagnostic accuracy of RNFL and segmented macular regions (GCIPL, GCC) scans were similar and higher than total macular thickness. This study provides a synthesis of contemporary evidence with features of robust inclusion criteria and large sample size. These findings may provide guidance to clinicians when navigating this rapidly evolving diagnostic area characterized by numerous options. PMID:29300765

Morphological Features and Important Parameters of Large Optic Discs for Diagnosing Glaucoma

PubMed Central

Okimoto, Satoshi; Yamashita, Keiko; Shibata, Tetsuo; Kiuchi, Yoshiaki

2015-01-01

Purpose To compare the optic disc parameters of glaucomatous eyes to those of non-glaucomatous eyes with large discs. Methods We studied 225 consecutive eyes with large optic discs (>2.82 mm2): 91 eyes with glaucoma and 134 eyes without glaucoma. An eye was diagnosed with glaucoma when visual field defects were detected by the Humphrey Field Analyzer. All of the Heidelberg Retina Tomograph II (HRT II) parameters were compared between the non-glaucomatous and glaucomatous eyes. A logistic regression analysis of the HRT II parameters was used to establish a new formula for diagnosing glaucoma, and the sensitivity and specificity of the Moorfields Regression Analysis (MRA) was compared to the findings made by our analyses. Results The mean disc area was 3.44±0.50 mm2 in the non-glaucomatous group and 3.40±0.52 mm2 in the glaucoma group. The cup area, cup volume, cup-to-disc area ratio, linear cup/disc ratio, mean cup depth, and the maximum cup depth were significantly larger in glaucomatous eyes than in the non-glaucomatous eyes. The rim area, rim volume, cup shape measurement, mean retinal nerve fiber layer (RNFL) thickness, and RFNL cross-sectional area were significantly smaller in glaucomatous eyes than in non-glaucomatous eyes. The cup-to-disc area ratio, the height variation contour (HVC), and the RNFL cross-sectional area were important parameters for diagnosing the early stage glaucoma, and the cup-to-disc area ratio and cup volume were useful for diagnosing advanced stage glaucoma in eyes with a large optic disc. The new formula had higher sensitivity and specificity for diagnosing glaucoma than MRA. Conclusions The cup-to-disc area ratio, HVC, RNFL cross-sectional area, and cup volume were important parameters for diagnosing glaucoma in eyes with a large optic disc. The important disc parameters to diagnose glaucoma depend on the stage of glaucoma in patients with large discs. PMID:25798580

Contrast Sensitivity Perimetry and Clinical Measures of Glaucomatous Damage

PubMed Central

Swanson, William H.; Malinovsky, Victor E.; Dul, Mitchell W.; Malik, Rizwan; Torbit, Julie K.; Sutton, Bradley M.; Horner, Douglas G.

2014-01-01

ABSTRACT Purpose To compare conventional structural and functional measures of glaucomatous damage with a new functional measure—contrast sensitivity perimetry (CSP-2). Methods One eye each was tested for 51 patients with glaucoma and 62 age-similar control subjects using CSP-2, size III 24-2 conventional automated perimetry (CAP), 24-2 frequency-doubling perimetry (FDP), and retinal nerve fiber layer (RNFL) thickness. For superior temporal (ST) and inferior temporal (IT) optic disc sectors, defect depth was computed as amount below mean normal, in log units. Bland-Altman analysis was used to assess agreement on defect depth, using limits of agreement and three indices: intercept, slope, and mean difference. A criterion of p < 0.0014 for significance used Bonferroni correction. Results Contrast sensitivity perimetry-2 and FDP were in agreement for both sectors. Normal variability was lower for CSP-2 than for CAP and FDP (F > 1.69, p < 0.02), and Bland-Altman limits of agreement for patient data were consistent with variability of control subjects (mean difference, −0.01 log units; SD, 0.11 log units). Intercepts for IT indicated that CSP-2 and FDP were below mean normal when CAP was at mean normal (t > 4, p < 0.0005). Slopes indicated that, as sector damage became more severe, CAP defects for IT and ST deepened more rapidly than CSP-2 defects (t > 4.3, p < 0.0005) and RNFL defects for ST deepened more slowly than for CSP, FDP, and CAP. Mean differences indicated that FDP defects for ST and IT were on average deeper than RNFL defects, as were CSP-2 defects for ST (t > 4.9, p < 0.0001). Conclusions Contrast sensitivity perimetry-2 and FDP defects were deeper than CAP defects in optic disc sectors with mild damage and revealed greater residual function in sectors with severe damage. The discordance between different measures of glaucomatous damage can be accounted for by variability in people free of disease. PMID:25259758

Contrast sensitivity perimetry and clinical measures of glaucomatous damage.

PubMed

Swanson, William H; Malinovsky, Victor E; Dul, Mitchell W; Malik, Rizwan; Torbit, Julie K; Sutton, Bradley M; Horner, Douglas G

2014-11-01

To compare conventional structural and functional measures of glaucomatous damage with a new functional measure-contrast sensitivity perimetry (CSP-2). One eye each was tested for 51 patients with glaucoma and 62 age-similar control subjects using CSP-2, size III 24-2 conventional automated perimetry (CAP), 24-2 frequency-doubling perimetry (FDP), and retinal nerve fiber layer (RNFL) thickness. For superior temporal (ST) and inferior temporal (IT) optic disc sectors, defect depth was computed as amount below mean normal, in log units. Bland-Altman analysis was used to assess agreement on defect depth, using limits of agreement and three indices: intercept, slope, and mean difference. A criterion of p < 0.0014 for significance used Bonferroni correction. Contrast sensitivity perimetry-2 and FDP were in agreement for both sectors. Normal variability was lower for CSP-2 than for CAP and FDP (F > 1.69, p < 0.02), and Bland-Altman limits of agreement for patient data were consistent with variability of control subjects (mean difference, -0.01 log units; SD, 0.11 log units). Intercepts for IT indicated that CSP-2 and FDP were below mean normal when CAP was at mean normal (t > 4, p < 0.0005). Slopes indicated that, as sector damage became more severe, CAP defects for IT and ST deepened more rapidly than CSP-2 defects (t > 4.3, p < 0.0005) and RNFL defects for ST deepened more slowly than for CSP, FDP, and CAP. Mean differences indicated that FDP defects for ST and IT were on average deeper than RNFL defects, as were CSP-2 defects for ST (t > 4.9, p < 0.0001). Contrast sensitivity perimetry-2 and FDP defects were deeper than CAP defects in optic disc sectors with mild damage and revealed greater residual function in sectors with severe damage. The discordance between different measures of glaucomatous damage can be accounted for by variability in people free of disease.

SEM and EDS investigation of a pyrolytic carbon covered C/C composite maxillofacial implant retrieved from the human body after 8 years.

PubMed

Sebők, Béla; Kiss, Gábor; Szabó, Péter J; Rigler, Dániel; Molnár, Milán L; Dobos, Gábor; Réti, Ferenc; Szőcs, Hajnal; Joób, Arpád F; Bogdán, Sándor; Szabó, György

2013-03-01

The long term effect of the human body on a pyrolytic carbon covered C/C composite maxillofacial implant (CarBulat(Tm)) was investigated by comparing the structure, the surface morphology and composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Although the thickness of the carbon fibres constituting the implants did not change during the 8 year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Calcium can only be detected on the surface as a trace element implying that the new layer is not formed by bone tissue. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering to implants.

Asymmetric Macular Structural Damage Is Associated With Relative Afferent Pupillary Defects in Patients With Glaucoma

PubMed Central

Gracitelli, Carolina P. B.; Tatham, Andrew J.; Zangwill, Linda M.; Weinreb, Robert N.; Abe, Ricardo Y.; Diniz-Filho, Alberto; Paranhos, Augusto; Baig, Saif; Medeiros, Felipe A.

2016-01-01

Purpose We examined the relationship between relative afferent pupillary defects (RAPDs) and macular structural damage measured by macular thickness and macular ganglion cell-inner plexiform layer (mGCIPL) thickness in patients with glaucoma. Methods A cross-sectional study was done of 106 glaucoma patients and 85 healthy individuals from the Diagnostic Innovations in Glaucoma Study. All subjects underwent standard automated perimetry (SAP) and optic nerve and macular imaging using Cirrus Spectral Domain Optical Coherence Tomography (SDOCT). Glaucoma was defined as repeatable abnormal SAP or progressive glaucomatous changes on stereo photographs. Pupil responses were assessed using an automated pupillometer, which records the magnitude of RAPD (RAPD score), with additional RAPD scores recorded for each of a series of colored stimuli (blue, red, green, and yellow). The relationship between RAPD score and intereye differences (right minus left eye) in circumpapillary retinal nerve fiber layer (cpRNFL) thickness, mGCIPL, macular thickness, and SAP mean deviation (MD), was examined using linear regression. Results There was fair correlation between RAPD score and asymmetric macular structural damage measured by intereye difference in mGCIPL thickness (R2 = 0.285, P < 0.001). The relationship between RAPD score and intereye difference in macular thickness was weaker (R2 = 0.167, P < 0.001). Intereye difference in cpRNFL thickness (R2 = 0.350, P < 0.001) and SAP MD (R2 = 0.594, P < 0.001) had stronger association with RAPD scores compared to intereye difference in mGCIPL and macular thickness. Conclusions Objective assessment of pupillary responses using a pupillometer was associated with asymmetric macular structural damage in patients with glaucoma. PMID:27064394

Development of machine learning models for diagnosis of glaucoma.

PubMed

Kim, Seong Jae; Cho, Kyong Jin; Oh, Sejong

2017-01-01

The study aimed to develop machine learning models that have strong prediction power and interpretability for diagnosis of glaucoma based on retinal nerve fiber layer (RNFL) thickness and visual field (VF). We collected various candidate features from the examination of retinal nerve fiber layer (RNFL) thickness and visual field (VF). We also developed synthesized features from original features. We then selected the best features proper for classification (diagnosis) through feature evaluation. We used 100 cases of data as a test dataset and 399 cases of data as a training and validation dataset. To develop the glaucoma prediction model, we considered four machine learning algorithms: C5.0, random forest (RF), support vector machine (SVM), and k-nearest neighbor (KNN). We repeatedly composed a learning model using the training dataset and evaluated it by using the validation dataset. Finally, we got the best learning model that produces the highest validation accuracy. We analyzed quality of the models using several measures. The random forest model shows best performance and C5.0, SVM, and KNN models show similar accuracy. In the random forest model, the classification accuracy is 0.98, sensitivity is 0.983, specificity is 0.975, and AUC is 0.979. The developed prediction models show high accuracy, sensitivity, specificity, and AUC in classifying among glaucoma and healthy eyes. It will be used for predicting glaucoma against unknown examination records. Clinicians may reference the prediction results and be able to make better decisions. We may combine multiple learning models to increase prediction accuracy. The C5.0 model includes decision rules for prediction. It can be used to explain the reasons for specific predictions.

Cupping in the Monkey Optic Nerve Transection Model Consists of Prelaminar Tissue Thinning in the Absence of Posterior Laminar Deformation

PubMed Central

Ing, Eliesa; Ivers, Kevin M.; Yang, Hongli; Gardiner, Stuart K.; Reynaud, Juan; Cull, Grant; Wang, Lin; Burgoyne, Claude F.

2016-01-01

Purpose To use optical coherence tomography (OCT) to test the hypothesis that optic nerve head (ONH) “cupping” in the monkey optic nerve transection (ONT) model does not include posterior laminar deformation. Methods Five monkeys (aged 5.5–7.8 years) underwent ONH and retinal nerve fiber layer (RNFL) OCT imaging five times at baseline and biweekly following unilateral ONT until euthanization at ∼40% RNFL loss. Retinal nerve fiber layer thickness (RNFLT) and minimum rim width (MRW) were calculated from each pre- and post-ONT imaging session. The anterior lamina cribrosa surface (ALCS) was delineated within baseline and pre-euthanasia data sets. Significant ONT versus control eye pre-euthanasia change in prelaminar tissue thickness (PLTT), MRW, RNFLT, and ALCS depth (ALCSD) was determined using a linear mixed-effects model. Eye-specific change in each parameter exceeded the 95% confidence interval constructed from baseline measurements. Results Animals were euthanized 49 to 51 days post ONT. Overall ONT eye change from baseline was significant for MRW (−26.2%, P = 0.0011), RNFLT (−43.8%, P < 0.0001), PLTT (−23.8%, P = 0.0013), and ALCSD (−20.8%, P = 0.033). All five ONT eyes demonstrated significant eye-specific decreases in MRW (−23.7% to −31.8%) and RNFLT (−39.6% to −49.7%). Four ONT eyes showed significant PLTT thinning (−23.0% to −28.2%). The ALCS was anteriorly displaced in three of the ONT eyes (−25.7% to −39.2%). No ONT eye demonstrated posterior laminar displacement. Conclusions Seven weeks following surgical ONT in the monkey eye, ONH cupping involves prelaminar and rim tissue thinning without posterior deformation of the lamina cribrosa. PMID:27168368

Improving Glaucoma Detection Using Spatially Correspondent Clusters of Damage and by Combining Standard Automated Perimetry and Optical Coherence Tomography

PubMed Central

Raza, Ali S.; Zhang, Xian; De Moraes, Carlos G. V.; Reisman, Charles A.; Liebmann, Jeffrey M.; Ritch, Robert; Hood, Donald C.

2014-01-01

Purpose. To improve the detection of glaucoma, techniques for assessing local patterns of damage and for combining structure and function were developed. Methods. Standard automated perimetry (SAP) and frequency-domain optical coherence tomography (fdOCT) data, consisting of macular retinal ganglion cell plus inner plexiform layer (mRGCPL) as well as macular and optic disc retinal nerve fiber layer (mRNFL and dRNFL) thicknesses, were collected from 52 eyes of 52 healthy controls and 156 eyes of 96 glaucoma suspects and patients. In addition to generating simple global metrics, SAP and fdOCT data were searched for contiguous clusters of abnormal points and converted to a continuous metric (pcc). The pcc metric, along with simpler methods, was used to combine the information from the SAP and fdOCT. The performance of different methods was assessed using the area under receiver operator characteristic curves (AROC scores). Results. The pcc metric performed better than simple global measures for both the fdOCT and SAP. The best combined structure-function metric (mRGCPL&SAP pcc, AROC = 0.868 ± 0.032) was better (statistically significant) than the best metrics for independent measures of structure and function. When SAP was used as part of the inclusion and exclusion criteria, AROC scores increased for all metrics, including the best combined structure-function metric (AROC = 0.975 ± 0.014). Conclusions. A combined structure-function metric improved the detection of glaucomatous eyes. Overall, the primary sources of value-added for glaucoma detection stem from the continuous cluster search (the pcc), the mRGCPL data, and the combination of structure and function. PMID:24408977

Predictors of vision impairment in Multiple Sclerosis.

PubMed

Sanchez-Dalmau, Bernardo; Martinez-Lapiscina, Elena H; Pulido-Valdeolivas, Irene; Zubizarreta, Irati; Llufriu, Sara; Blanco, Yolanda; Sola-Valls, Nuria; Sepulveda, Maria; Guerrero, Ana; Alba, Salut; Andorra, Magi; Camos, Anna; Sanchez-Vela, Laura; Alfonso, Veronica; Saiz, Albert; Villoslada, Pablo

2018-01-01

Visual impairment significantly alters the quality of life of people with Multiple Sclerosis (MS). The objective of this study was to identify predictors (independent variables) of visual outcomes, and to define their relationship with neurological disability and retinal atrophy when assessed by optical coherence tomography (OCT). We performed a cross-sectional analysis of 119 consecutive patients with MS, assessing vision using high contrast visual acuity (LogMar), 2.5% and 1.25% low contrast visual acuity (Sloan charts), and color vision (Hardy-Rand-Rittler plates). Quality of vision is a patient reported outcome based on an individual's unique perception of his or her vision and was assessed with the Visual Functioning Questionnaire-25 (VFQ-25) with the 10 neuro-ophthalmologic items. MS disability was assessed using the expanded disability status scale (EDSS), the MS functional composite (MSFC) and the brief repetitive battery-neuropsychology (BRB-N). Retinal atrophy was assessed using spectral domain OCT, measuring the thickness of the peripapillar retinal nerve fiber layer (pRNFL) and the volume of the ganglion cell plus inner plexiform layer (GCIPL). The vision of patients with MS was impaired, particularly in eyes with prior optic neuritis. Retinal atrophy (pRNFL and GCIPL) was closely associated with impaired low contrast vision and color vision, whereas the volume of the GCIPL showed a trend (p = 0.092) to be associated with quality of vision. Multiple regression analysis revealed that EDSS was an explanatory variable for high contrast vision after stepwise analysis, GCIPL volume for low contrast vision, and GCIPL volume and EDSS for color vision. The explanatory variables for quality of vision were high contrast vision and color vision. In summary, quality of vision in MS depends on the impairment of high contrast visual acuity and color vision due to the disease.

Retinal nerve fiber layer thickness analysis in suspected malingerers with optic disc temporal pallor

PubMed Central

Civelekler, Mustafa; Halili, Ismail; Gundogan, Faith C; Sobaci, Gungor

2009-01-01

Purpose: To investigate the value of temporal retinal nerve fiber layer (RNFLtemporal) thickness in the prediction of malingering. Materials and Methods: This prospective, cross-sectional study was conducted on 33 military conscripts with optic disc temporal pallor (ODTP) and 33 age-and sex-matched healthy controls. Initial visual acuity (VAi) and visual acuity after simulation examination techniques (VAaset) were assessed. The subjects whose VAaset were two or more lines higher than VAi were determined as malingerers. Thickness of the peripapillary RNFL was determined with OCT (Stratus OCT™, Carl Zeiss Meditec, Inc.). RNFLtemporal thickness of the subjects were categorized into one of the 1+ to 4+ groups according to 50% confidence interval (CI), 25% CI and 5% CI values which were assessed in the control group. The VAs were converted to LogMAR-VAs for statistical comparisons. Results: A significant difference was found only in the temporal quadrant of RNFL thickness in subjects with ODTP (P=0.002). Mean LogMAR-VA increased significantly after SETs (P<0.001). Sensitivity, specificity, positive and negative predictive values of categorized RNFLtemporal thickness in diagnosing malingering were 84.6%, 75.0%, 68.8%, 88.2%, respectively. ROC curve showed that RNFLtemporal thickness of 67.5 μm is a significant cut-off point in determining malingering (P=0.001, area under the curve:0.862). The correlations between LogMAR-VAs and RNFLtemporal thicknesses were significant; the correlation coefficient for LogMAR-VAi was lower than the correlation for LogMAR-VAaset (r=−0.447, P=0.009 for LogMAR-VAi; r=−0.676, P<0.001 for LogMAR-VAaset). Conclusions: RNFLtemporal thickness assessment may be a valuable tool in determining malingering in subjects with ODTP objectively. PMID:19700875

Damage and failure modelling of hybrid three-dimensional textile composites: a mesh objective multi-scale approach.

PubMed

Patel, Deepak K; Waas, Anthony M

2016-07-13

This paper is concerned with predicting the progressive damage and failure of multi-layered hybrid textile composites subjected to uniaxial tensile loading, using a novel two-scale computational mechanics framework. These composites include three-dimensional woven textile composites (3DWTCs) with glass, carbon and Kevlar fibre tows. Progressive damage and failure of 3DWTCs at different length scales are captured in the present model by using a macroscale finite-element (FE) analysis at the representative unit cell (RUC) level, while a closed-form micromechanics analysis is implemented simultaneously at the subscale level using material properties of the constituents (fibre and matrix) as input. The N-layers concentric cylinder (NCYL) model (Zhang and Waas 2014 Acta Mech. 225, 1391-1417; Patel et al. submitted Acta Mech.) to compute local stress, srain and displacement fields in the fibre and matrix is used at the subscale. The 2-CYL fibre-matrix concentric cylinder model is extended to fibre and (N-1) matrix layers, keeping the volume fraction constant, and hence is called the NCYL model where the matrix damage can be captured locally within each discrete layer of the matrix volume. The influence of matrix microdamage at the subscale causes progressive degradation of fibre tow stiffness and matrix stiffness at the macroscale. The global RUC stiffness matrix remains positive definite, until the strain softening response resulting from different failure modes (such as fibre tow breakage, tow splitting in the transverse direction due to matrix cracking inside tow and surrounding matrix tensile failure outside of fibre tows) are initiated. At this stage, the macroscopic post-peak softening response is modelled using the mesh objective smeared crack approach (Rots et al. 1985 HERON 30, 1-48; Heinrich and Waas 2012 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, Honolulu, HI, 23-26 April 2012 AIAA 2012-1537). Manufacturing-induced geometric imperfections are included in the simulation, where the FE mesh of the unit cell is generated directly from micro-computed tomography (MCT) real data using a code Simpleware Results from multi-scale analysis for both an idealized perfect geometry and one that includes geometric imperfections are compared with experimental results (Pankow et al. 2012 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, Honolulu, HI, 23-26 April 2012 AIAA 2012-1572). This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. © 2016 The Author(s).

Tensile Response of Hoop Reinforced Multiaxially Braided Thin Wall Composite Tubes

NASA Astrophysics Data System (ADS)

Roy, Sree Shankhachur; Potluri, Prasad; Soutis, Constantinos

2017-04-01

This paper presents the tensile response of thin-walled composite tubes with multi-axial fibre architecture. A hybrid braid-wound layup has the potential to optimise the composite tube properties, however, stacking sequence plays a role in the failure mechanism. A braid-winding method has been used to produce stacked overwound braid layup [(±45°/0°)5/90°4]T. Influence of stacking sequence on premature failure of hoop layers has been reported. Under tensile loading, a cross-ply composite tube with the alternate stacking of hoop and axial fibre show hoop plies splitting similar to the overwound braided composite tube. However, splitting has been restricted by the surrounding axial plies and contained between the adjacent axial fibre tows. This observation suggests hoop layers sandwiched between braid layers will improve structural integrity. A near net shape architecture with three fibre orientation in a triaxial braid will provide additional support to prevent extensive damage for plies loaded in off-axis. Several notable observations for relatively open braid structures such as tow scissoring, high Poisson's ratio and influence of axial tow crimp on the strain to failure have been reported. Digital Image Correlation (DIC) in conjunction with surface strain gauging has been employed to capture the strain pattern.

Recycling of woven carbon-fibre-reinforced polymer composites using supercritical water.

PubMed

Knight, Chase C; Zeng, Changchun; Zhang, Chuck; Wang, Ben

2012-01-01

Over the past few years, there has been great deal of interest in recycling carbon-fibre-reinforced polymer composites. One method that has shown promising results involves the use of supercritical fluids to achieve separation between matrix and fibres by effectively degrading the resin into lower molecular weight compounds. In addition, the solvents used are environmentally benign and can also be recovered and reused. In this study, supercritical water with 0.05 M KOH as the catalyst was used for the recycling of an aerospace-grade high-performance epoxy carbon fibre composite (Hexcel 8552/IM7). The morphology of the reclaimed fibres was observed by scanning electron microscopy, and the tensile properties of the fibres were measured by single filament testing. The effects of processing time on the resin elimination efficiency and fibre property retention were investigated. With the process developed in this research, as much as 99.2 wt% resin elimination was achieved, resulting in the recovery of clean, undamaged fibres. The reclaimed fibres retained the original tensile strength. The feasibility of recycling multiple layer composites was also explored.

UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

NASA Astrophysics Data System (ADS)

Chong, J. Y.; Aba, N. F. D.; Wang, B.; Mattevi, C.; Li, K.

2015-11-01

Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m-2 h-1 bar-1 for water, and 0.14 to 7.5 L m-2 h-1 bar-1 for acetone, with an unchanged low molecular weight cut off (~250 Da).

Secondary cell-wall assembly in flax phloem fibres: role of galactans.

PubMed

Gorshkova, Tatyana; Morvan, Claudine

2006-01-01

Non-lignified fibre cells (named gelatinous fibres) are present in tension wood and the stems of fibre crops (such as flax and hemp). These cells develop a very thick S2 layer within the secondary cell wall, which is characterised by (1) cellulose microfibrils largely parallel to the longitudinal axis of the cell, and (2) a high proportion of galactose-containing polymers among the non-cellulosic polysaccharides. In this review, we focus on the role of these polymers in the assembly of gelatinous fibres of flax. At the different stages of fibre development, we analyse in detail data based on sugar composition, linkages of pectic polymers, and immunolocalisation of the beta-(1-->4)-galactans. These data indicate that high molecular-mass gelatinous galactans accumulate in specialised Golgi-derived vesicles during fibre cell-wall thickening. They consist of RG-I-like polymers with side chains of beta-(1-->4)-linked galactose. Most of them are short, but there are also long chains containing up to 28 galactosyl residues. At fibre maturity, two types of cross-linked galactans are identified, a C-L structure that resembles the part of soluble galactan with long side chains and a C-S structure with short chains. Different possibilities for soluble galactan to give rise to C-L and C-S are analysed. In addition, we discuss the prospect for the soluble galactan in preventing the newly formed cellulose chains from completing immediate crystallisation. This leads to a hypothesis that firstly the secretion of soluble galactans plays a role in the axial orientation of cellulose microfibrils, and secondly the remodelling and cross-linking of pectic galactans are linked to the dehydration and the assembly of S2 layer.

Relationship between white matter hyperintensities and retinal nerve fiber layer, choroid, and ganglion cell layer thickness in migraine patients.

PubMed

Iyigundogdu, Ilkin; Derle, Eda; Asena, Leyla; Kural, Feride; Kibaroglu, Seda; Ocal, Ruhsen; Akkoyun, Imren; Can, Ufuk

2018-02-01

Aim To compare the relationship between white matter hyperintensities (WMH) on brain magnetic resonance imaging and retinal nerve fiber layer (RNFL), choroid, and ganglion cell layer (GCL) thicknesses in migraine patients and healthy subjects. We also assessed the role of cerebral hypoperfusion in the formation of these WMH lesions. Methods We enrolled 35 migraine patients without WMH, 37 migraine patients with WMH, and 37 healthy control subjects examined in the Neurology outpatient clinic of our tertiary center from May to December 2015. RFNL, choroid, and GCL thicknesses were measured by optic coherence tomography. Results There were no differences in the RFNL, choroid, or GCL thicknesses between migraine patients with and without WMH ( p > 0.05). Choroid layer thicknesses were significantly lower in migraine patients compared to control subjects ( p < 0.05), while there were no differences in RFNL and GCL thicknesses ( p > 0.05). Conclusions The 'only cerebral hypoperfusion' theory was insufficient to explain the pathophysiology of WMH lesions in migraine patients. In addition, the thinning of the choroid thicknesses in migraine patients suggests a potential causative role for cerebral hypoperfusion and decreased perfusion pressure of the choroid layer.

Highly birefringent large negative dispersion-flattened photonic crystal fibre for broadband residual dispersion compensation

NASA Astrophysics Data System (ADS)

Faisal, Mohammad; Bala, Animesh; Roy Chowdhury, Kanan; Mia, Md. Borhan

2018-07-01

A triangular lattice photonic crystal fibre is presented in this paper for residual dispersion compensation. The fibre exhibits a flattened negative dispersion of -992.01 ± 6.93 ps/(nm-km) over S+C+L wavelength bands and -995.83 ± 0.42 ps/(nm-km) over C-band. The birefringence is about 4.4 × 10-2 at the excitation wavelength of 1550 nm which is also very high. Full vector finite element method (FEM) with a perfectly matched absorbing layer (PML) boundary condition is applied to numerically investigate the guiding properties of this PCF. The fibre operates at fundamental mode only. All these properties endorse this fibre as a suitable candidate for compensating residual dispersion and polarization maintaining applications.

Comparison of optical coherence tomography findings and visual field changes in patients with primary open-angle glaucoma and amyotrophic lateral sclerosis.

PubMed

Liu, Ziyuan; Wang, Hongli; Fan, Dongsheng; Wang, Wei

2018-02-01

Recent studies revealing genetic connection of primary open angle glaucoma (POAG) and amyotrophic lateral sclerosis (ALS) have received particular attention. Exploring the evidence for common pathogenesis of these two progressive neurological disorders may assist in understanding the mechanism and searching for new treatment. Retinal nerve fiber layer (RNFL) defect and corresponding visual field (VF) impairment are well known neuropathy signs in glaucoma. In our study, thickness of certain retinal layer in ALS patients was analyzed to detect ganglion cell's soma and axon, and for first time visual field was examined for ALS. The correlation of retinal involvement and ALS progression were also investigated. The results were compared with those of POAG. The study may provide new knowledge for these two neurodegenerative diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel electrospun gas diffusion layers for polymer electrolyte membrane fuel cells: Part II. In operando synchrotron imaging for microscale liquid water transport characterization

NASA Astrophysics Data System (ADS)

Chevalier, S.; Ge, N.; Lee, J.; George, M. G.; Liu, H.; Shrestha, P.; Muirhead, D.; Lavielle, N.; Hatton, B. D.; Bazylak, A.

2017-06-01

This is the second paper in a two-part series in which we investigate the impact of the gas diffusion layer structure on the liquid water distribution in an operating polymer electrolyte membrane (PEM) fuel cell through the procedures of design, fabrication, and testing of novel hydrophobic electrospun gas diffusion layers (eGDLs). In this work, fibre diameters and alignment in eGDLs are precisely controlled, and concurrent synchrotron X-ray radiography and electrochemical impedance spectroscopy (EIS) are used to evaluate the influence of the controlled eGDL parameters on the liquid water distribution and on membrane liquid water content. For eGDLs with small fibre diameters (150-200 nm) and correspondingly smaller pore sizes, reduced liquid water accumulation under the flow field ribs is observed. However, more liquid water is pinned onto the eGDL - at the interface with flow field channels. Orienting fibre alignment perpendicular to the flow field channel direction leads to improved eGDL-catalyst layer contact and prevents rib-channel membrane deformation. On the other hand, eGDLs facilitate significant membrane dry-out, even under highly humidified operating conditions at high current densities.

Novel electrospun gas diffusion layers for polymer electrolyte membrane fuel cells: Part I. Fabrication, morphological characterization, and in situ performance

NASA Astrophysics Data System (ADS)

Chevalier, S.; Lavielle, N.; Hatton, B. D.; Bazylak, A.

2017-06-01

In this first of a series of two papers, we report an in-depth analysis of the impact of the gas diffusion layer (GDL) structure on the polymer electrolyte membrane (PEM) fuel cell performance through the use of custom GDLs fabricated in-house. Hydrophobic electrospun nanofibrous gas diffusion layers (eGDLs) are fabricated with controlled fibre diameter and alignment. The eGDLs are rendered hydrophobic through direct surface functionalization, and this molecular grafting is achieved in the absence of structural alteration. The fibre diameter, chemical composition, and electrical conductivity of the eGDL are characterized, and the impact of eGDL structure on fuel cell performance is analysed. We observe that the eGDL facilitates higher fuel cell power densities compared to a commercial GDL (Toray TGP-H-60) at highly humidified operating conditions. The ohmic resistance of the fuel cell is found to significantly increase with increasing inter-fiber distance. It is also observed that the addition of a hydrophobic treatment enhances membrane hydration, and fibres perpendicularly aligned to the channel direction may enhance the contact area between the catalyst layer and the GDL.

Impact and hardness optimisation of composite materials inspired by the babassu nut (Orbignya speciosa).

PubMed

Staufenberg, Gerrit; Graupner, Nina; Müssig, Jörg

2015-08-20

The babassu nut is the fruit of the babassu palm Orbignya speciosa. The combination of hardness and impact strength is difficult to acquire for artificial materials, making the babassu nut a promising source for biomimetic inspiration. Unnotched Charpy impact tests, Shore D hardness tests and scanning electron microscopy were used for mechanical and microscopical analysis of the pericarp. Four major principles were found for a biomimetic approach: a hard core ((1); endocarp) is embedded in a soft outer layer of high impact strength ((2); epicarp) and is reinforced with fibres of variable fineness (3), some of which are oriented radial to the core (4). Biomimetic fibre-reinforced composites were produced using abstracted mechanisms of the babassu nut based on regenerated cellulose fibres (lyocell, L) with two different fineness values as reinforcement embedded in a polylactide (PLA) core matrix and polypropylene (PP) based outer layers. The biomimetic fibre composite reaches a significantly higher impact strength that is 1.6 times higher than the reference sample produced from a PLA/PP/L-blend. At the same time the hardness is slightly increased compared to PP/L.

The deep muscular plexus of the pig duodenum: a histochemical and ultrastructural study with special reference to the interstitial cells.

PubMed

Henry, M; Porcher, C; Julé, Y

1998-06-10

The aim of the present study was to describe the deep muscular plexus of the pig duodenum and to characterize its cellular components. Numerous nerve varicosities have been detected in the deep muscular plexus using anti-synaptophysin antibodies. Nerve fibres were also detected here in the outer circular muscle layer, whereas no nerve fibres were observed in the inner circular muscle layer. In the deep muscular plexus, nerve fibres projected to interstitial cells which were characterized at the ultrastructural level. The interstitial cells were of two kinds: the interstitial fibroblastic-like cells (FLC) and the interstitial dense cells (IDC), both of which were interposed between nerve fibres and smooth muscle cells. The FLC were characterized by their elongated bipolar shape, the lack of basal lamina, a well-developed endoplasmic reticulum, a Golgi apparatus, and intermediate filaments. They were closely apposed to axon terminals containing small clear synaptic vesicles and/or dense-cored vesicles. They were frequently connected to each other and to smooth muscle cells of the inner and outer circular layer by desmosomes and more rarely by gap junctions. The IDC are myoid-like cells. They had a stellate appearance and were characterized by a dense cell body, numerous caveolae, and a discontinuous basal lamina. The IDC were always closely apposed to nerve fibres and were connected to smooth muscle cells by desmosomes and small gap junctions. The present results show the unique pattern of cellular organization of the deep muscular plexus of the pig small intestine. They suggest that the interstitial cells in the deep muscular plexus are involved in the integration and transmission of nervous inputs from myenteric neurons to the inner and outer circular muscle layers. The clear-cut distinction observed here between the two types of interstitial cells (fibroblastic and myoid-like) suggests that the interstitial cells of each type may also be involved in some other specific activity, which still remains to be determined.

Distribution of enkephalin-like immunoreactivity in the cat digestive tract.

PubMed

Bagnol, D; Henry, M; Cupo, A; Julé, Y

1997-05-12

Immunohistochemical investigations were carried out to determine the pattern of distribution of methionine- and leucine-enkephalin-like materials in the cat pylorus, duodenum, ileum and proximal and distal colon. The present results indicate that leucine-enkephalin-like materials are less densely distributed than methionine-enkephalin-like materials, but that the two patterns of distribution show some similarities. Considerable regional differences exist however in the distribution of these enkephalin-like materials in the muscular layers. In the duodenum, ileum and proximal colon, the immunoreactivity was mainly confined to the myenteric plexus and the circular muscle layer, where it was present in nerve cell bodies and in numerous fibres. In the longitudinal muscle and submucous layers, a few immunoreactive fibres were observed which sometimes surrounded blood vessels. In the pylorus and the distal colon, however, numerous immunoreactive fibres were observed in the longitudinal and circular muscle layers; the immunoreactivity was detected in the cell bodies of numerous myenteric plexus neurons but those of only a few submucous plexus neurons. In addition, the pylorus tissues contained immunoreactive plexi which were localized either within the longitudinal muscle or between the serosa and the longitudinal muscle layer. These plexi were connected to the myenteric plexus by immunoreactive nerve strands. In all the small intestinal segments studied, numerous immunoreactive varicosities were present in the deep muscular plexus, in the inner part of the circular muscle layer. Our results suggest that in cats, the nervous control of external muscular layers mediated by enkephalins shows regional differences. In the pylorus and the distal colon, it involves both the longitudinal and circular muscle layers, whereas in other intestinal segments, only the circular muscle layer is involved.

Elastic fibres in the vesicourethral junction and urethra of the guinea pig: quantification with computerised image analysis

PubMed Central

DASS, NARINDER; McMURRAY, GORDON; BRADING, ALISON F.

1999-01-01

Elastic fibres, which are intimately associated with collagen, a major component of the urethra, have been assumed to contribute to the resting urethral closure pressure. The Miller stain for elastin was used to demonstrate elastic fibres in cryostat sections of guinea pig bladder base, vesicourethral junction (VUJ) and urethra. Computerised image analysis was employed to objectively quantify these fibres. Both male and female guinea pigs showed significantly greater amounts of circularly disposed elastic fibres in the VUJ than in the other 2 regions examined. This particular disposition of fibres may be responsible for imparting resiliency and plasticity to the VUJ, allowing it to distend and recoil repeatedly in response to urine outflow. Furthermore, the elastic fibres may be partly responsible for the passive occlusive force in this region. Elastic fibres in the distal urethra were not quantified because of their relative paucity. Sagittal sections of the urethra revealed a mass of longitudinally arranged elastic fibres localised almost exclusively within the mucosa, submucosa and longitudinal smooth muscle layer. Functionally, this arrangement may exist to facilitate urethral length changes that occur in micturition. PMID:10580860

Embedding Carbon Fibre Structures in Metal Matrixes for Additive Manufacturing

NASA Astrophysics Data System (ADS)

Frostevarg, Jan; Robertson, Stephanie; Benavides, Vicente; Soldatov, Alexander

It is possible to reinforce structures and components using carbon fibres for applications in electronics and medicine, but most commonly used in reinforcing resin fibre composites for personal protection equipment and light weight constructions. Carbon fibres act as stress redistributors while having increased electrical and thermal conductivities. These properties could also be utilized in metal matrixes, if the fibres are properly fused to the metal and the structure remains intact. Another recently developed high potential carbon structure, carbon nanotube- (CNT) yarns, has similar but even greater mechanical properties than common carbon fibres. Via laser cladding, these reinforcing materials could be used in a plethora of applications, either locally (or globally) as surface treatments or as structural reinforcements using multi-layer laser cladding (additive manufacturing). The challenges of embedding carbon fibres or CNT-yarns in a CuAl mixture and SnPb solder wire using lasers are here investigated using high speed imaging and SEM. It is revealed that the carbon fibres have very high buoyancy in the molten metal and quickly degrades when irradiated by the laser. Wetting of the fibres is shown to be improved by a Tungsten coating and embedding of the structures after processing are evaluated using SEM and Raman spectroscopy.

The design and performance of a scintillating-fibre tracker for the cosmic-ray muon tomography of legacy nuclear waste containers

NASA Astrophysics Data System (ADS)

Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnstone, J. R.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Staines, C.; Yang, G.; Zimmerman, C.

2014-05-01

Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons are increasingly being exploited for the non-destructive assay of shielded containers in a wide range of applications. One such application is the characterisation of legacy nuclear waste materials stored within industrial containers. The design, assembly and performance of a prototype muon tomography system developed for this purpose are detailed in this work. This muon tracker comprises four detection modules, each containing orthogonal layers of Saint-Gobain BCF-10 2 mm-pitch plastic scintillating fibres. Identification of the two struck fibres per module allows the reconstruction of a space point, and subsequently, the incoming and Coulomb-scattered muon trajectories. These allow the container content, with respect to the atomic number Z of the scattering material, to be determined through reconstruction of the scattering location and magnitude. On each detection layer, the light emitted by the fibre is detected by a single Hamamatsu H8500 MAPMT with two fibres coupled to each pixel via dedicated pairing schemes developed to ensure the identification of the struck fibre. The PMT signals are read out to standard charge-to-digital converters and interpreted via custom data acquisition and analysis software. The design and assembly of the detector system are detailed and presented alongside results from performance studies with data collected after construction. These results reveal high stability during extended collection periods with detection efficiencies in the region of 80% per layer. Minor misalignments of millimetre order have been identified and corrected in software. A first image reconstructed from a test configuration of materials has been obtained using software based on the Maximum Likelihood Expectation Maximisation algorithm. The results highlight the high spatial resolution provided by the detector system. Clear discrimination between the low, medium and high-Z materials assayed is also observed.

Numerical simulation of multi-layered textile composite reinforcement forming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, P.; Hamila, N.; Boisse, P.

2011-05-04

One important perspective in aeronautics is to produce large, thick or/and complex structural composite parts. The forming stage presents an important role during the whole manufacturing process, especially for LCM processes (Liquid Composites Moulding) or CFRTP (Continuous Fibre Reinforcements and Thermoplastic resin). Numerical simulations corresponding to multi-layered composite forming allow the prediction for a successful process to produce the thick parts, and importantly, the positions of the fibres after forming to be known. This paper details a set of simulation examples carried out by using a semi-discrete shell finite element made up of unit woven cells. The internal virtual workmore » is applied on all woven cells of the element taking into account tensions, in-plane shear and bending effects. As one key problem, the contact behaviours of tool/ply and ply/ply are described in the numerical model. The simulation results not only improve our understanding of the multi-layered composite forming process but also point out the importance of the fibre orientation and inter-ply friction during formability.« less

High-speed polarization sensitive optical coherence tomography for retinal diagnostics

NASA Astrophysics Data System (ADS)

Yin, Biwei; Wang, Bingqing; Vemishetty, Kalyanramu; Nagle, Jim; Liu, Shuang; Wang, Tianyi; Rylander, Henry G., III; Milner, Thomas E.

2012-01-01

We report design and construction of an FPGA-based high-speed swept-source polarization-sensitive optical coherence tomography (SS-PS-OCT) system for clinical retinal imaging. Clinical application of the SS-PS-OCT system is accurate measurement and display of thickness, phase retardation and birefringence maps of the retinal nerve fiber layer (RNFL) in human subjects for early detection of glaucoma. The FPGA-based SS-PS-OCT system provides three incident polarization states on the eye and uses a bulk-optic polarization sensitive balanced detection module to record two orthogonal interference fringe signals. Interference fringe signals and relative phase retardation between two orthogonal polarization states are used to obtain Stokes vectors of light returning from each RNFL depth. We implement a Levenberg-Marquardt algorithm on a Field Programmable Gate Array (FPGA) to compute accurate phase retardation and birefringence maps. For each retinal scan, a three-state Levenberg-Marquardt nonlinear algorithm is applied to 360 clusters each consisting of 100 A-scans to determine accurate maps of phase retardation and birefringence in less than 1 second after patient measurement allowing real-time clinical imaging-a speedup of more than 300 times over previous implementations. We report application of the FPGA-based SS-PS-OCT system for real-time clinical imaging of patients enrolled in a clinical study at the Eye Institute of Austin and Duke Eye Center.

Structural and functional brain changes in early- and mid-stage primary open-angle glaucoma using voxel-based morphometry and functional magnetic resonance imaging.

PubMed

Jiang, Ming-Ming; Zhou, Qing; Liu, Xiao-Yong; Shi, Chang-Zheng; Chen, Jian; Huang, Xiang-He

2017-03-01

To investigate structural and functional brain changes in patients with primary open-angle glaucoma (POAG) by using voxel-based morphometry based on diffeomorphic anatomical registration through exponentiated Lie algebra (VBM-DARTEL) and blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI), respectively.Thirteen patients diagnosed with POAG and 13 age- and sex-matched healthy controls were enrolled in the study. For each participant, high-resolution structural brain imaging and blood flow imaging were acquired on a 3.0-Tesla magnetic resonance imaging (MRI) scanner. Structural and functional changes between the POAG and control groups were analyzed. An analysis was carried out to identify correlations between structural and functional changes acquired in the previous analysis and the retinal nerve fiber layer (RNFL).Patients in the POAG group showed a significant (P < 0.001) volume increase in the midbrain, left brainstem, frontal gyrus, cerebellar vermis, left inferior parietal lobule, caudate nucleus, thalamus, precuneus, and Brodmann areas 7, 18, and 46. Moreover, significant (P < 0.001) BOLD signal changes were observed in the right supramarginal gyrus, frontal gyrus, superior frontal gyrus, left inferior parietal lobule, left cuneus, and left midcingulate area; many of these regions had high correlations with the RNFL.Patients with POAG undergo widespread and complex changes in cortical brain structure and blood flow. (ClinicalTrials.gov number: NCT02570867).

Improving our understanding, and detection, of glaucomatous damage: An approach based upon optical coherence tomography (OCT)

PubMed Central

Hood, Donald C.

2017-01-01

Although ophthalmologists are becoming increasingly reliant upon optical coherence tomography (OCT), clinicians who care for glaucoma patients are not taking full advantage of the potential of this powerful technology. First, we ask, how would one describe the nature of glaucomatous damage if only OCT scans were available? In particular, a schematic model of glaucomatous damage is developed in section 2, and the nature of glaucomatous damage seen on OCT scans described in the context of this model in section 3. In particular, we illustrate that local thinning of the circumpapillary retinal nerve fiber layer (cpRNFL) around the optic disc can vary in location, depth, and/or width, as well as homogeneity of damage. Second, we seek to better understand the relationship between the thinning of the cpRNFL and the various patterns of sensitivity loss seen on visual fields obtained with standard automated perimetry. In sections 4 and 5, we illustrate why one should expect a wide range of visual field patterns, and iilustrate why they should not be placed into discrete categories. Finally, section 6 describes how the clinician can take better advantage of the information in OCT scans. The approach is summarized in a single-page report, which can be generated from a single wide-field scan. The superiority of this approach, as opposed to the typical reliance on summary metrics, is described. PMID:28012881

Damage and failure modelling of hybrid three-dimensional textile composites: a mesh objective multi-scale approach

PubMed Central

Patel, Deepak K.

2016-01-01

This paper is concerned with predicting the progressive damage and failure of multi-layered hybrid textile composites subjected to uniaxial tensile loading, using a novel two-scale computational mechanics framework. These composites include three-dimensional woven textile composites (3DWTCs) with glass, carbon and Kevlar fibre tows. Progressive damage and failure of 3DWTCs at different length scales are captured in the present model by using a macroscale finite-element (FE) analysis at the representative unit cell (RUC) level, while a closed-form micromechanics analysis is implemented simultaneously at the subscale level using material properties of the constituents (fibre and matrix) as input. The N-layers concentric cylinder (NCYL) model (Zhang and Waas 2014 Acta Mech. 225, 1391–1417; Patel et al. submitted Acta Mech.) to compute local stress, srain and displacement fields in the fibre and matrix is used at the subscale. The 2-CYL fibre–matrix concentric cylinder model is extended to fibre and (N−1) matrix layers, keeping the volume fraction constant, and hence is called the NCYL model where the matrix damage can be captured locally within each discrete layer of the matrix volume. The influence of matrix microdamage at the subscale causes progressive degradation of fibre tow stiffness and matrix stiffness at the macroscale. The global RUC stiffness matrix remains positive definite, until the strain softening response resulting from different failure modes (such as fibre tow breakage, tow splitting in the transverse direction due to matrix cracking inside tow and surrounding matrix tensile failure outside of fibre tows) are initiated. At this stage, the macroscopic post-peak softening response is modelled using the mesh objective smeared crack approach (Rots et al. 1985 HERON 30, 1–48; Heinrich and Waas 2012 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, Honolulu, HI, 23–26 April 2012. AIAA 2012-1537). Manufacturing-induced geometric imperfections are included in the simulation, where the FE mesh of the unit cell is generated directly from micro-computed tomography (MCT) real data using a code Simpleware. Results from multi-scale analysis for both an idealized perfect geometry and one that includes geometric imperfections are compared with experimental results (Pankow et al. 2012 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, Honolulu, HI, 23–26 April 2012. AIAA 2012-1572). This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’. PMID:27242294

Ischaemia-reperfusion injury in central retinal artery occlusion.

PubMed

Saxena, Sandeep; Mishra, Nibha; Meyer, Carsten H; Akduman, Levent

2013-10-21

A 53-year-old man presented with sudden painless diminution of vision in his right eye for 3 days. His fundus examination showed diffuse whitening of the retina with a cherry red spot at the fovea with cilioretinal artery sparing. On fluorescein angiography delayed arteriovenous transit was observed. Three-dimensional spectral domain optical coherence tomography was used to assess retinal nerve fibre layer thickness and average macular central subfield thickness on days 3, 7, 30 and 90. Marked retinal oedema due to ischaemia was observed on day 3 of occurrence of central retinal artery occlusion. On day 7, significant decrease in retinal nerve fibre thickness and macular thickness was noted suggestive of acute reperfusion injury. Retinal nerve fibre layer thickness and macular thickness returned to near normal on day 30 due to restoration of blood supply with wash out of stress mediators. Retinal atrophy was observed on day 90.

Ischaemia-reperfusion injury in central retinal artery occlusion

PubMed Central

Saxena, Sandeep; Mishra, Nibha; Meyer, Carsten H; Akduman, Levent

2013-01-01

A 53-year-old man presented with sudden painless diminution of vision in his right eye for 3 days. His fundus examination showed diffuse whitening of the retina with a cherry red spot at the fovea with cilioretinal artery sparing. On fluorescein angiography delayed arteriovenous transit was observed. Three-dimensional spectral domain optical coherence tomography was used to assess retinal nerve fibre layer thickness and average macular central subfield thickness on days 3, 7, 30 and 90. Marked retinal oedema due to ischaemia was observed on day 3 of occurrence of central retinal artery occlusion. On day 7, significant decrease in retinal nerve fibre thickness and macular thickness was noted suggestive of acute reperfusion injury. Retinal nerve fibre layer thickness and macular thickness returned to near normal on day 30 due to restoration of blood supply with wash out of stress mediators. Retinal atrophy was observed on day 90. PMID:24145508

A multiphase model for chemically- and mechanically- induced cell differentiation in a hollow fibre membrane bioreactor: minimising growth factor consumption.

PubMed

Pearson, Natalie C; Oliver, James M; Shipley, Rebecca J; Waters, Sarah L

2016-06-01

We present a simplified two-dimensional model of fluid flow, solute transport, and cell distribution in a hollow fibre membrane bioreactor. We consider two cell populations, one undifferentiated and one differentiated, with differentiation stimulated either by growth factor alone, or by both growth factor and fluid shear stress. Two experimental configurations are considered, a 3-layer model in which the cells are seeded in a scaffold throughout the extracapillary space (ECS), and a 4-layer model in which the cell-scaffold construct occupies a layer surrounding the outside of the hollow fibre, only partially filling the ECS. Above this is a region of free-flowing fluid, referred to as the upper fluid layer. Following previous models by the authors (Pearson et al. in Math Med Biol, 2013, Biomech Model Mechanbiol 1-16, 2014a, we employ porous mixture theory to model the dynamics of, and interactions between, the cells, scaffold, and fluid in the cell-scaffold construct. We use this model to determine operating conditions (experiment end time, growth factor inlet concentration, and inlet fluid fluxes) which result in a required percentage of differentiated cells, as well as maximising the differentiated cell yield and minimising the consumption of expensive growth factor.

Organisation of autonomic nervous structures in the small intestine of chinchilla (Chinchilla laniger, Molina).

PubMed

Nowak, E

2014-08-01

Using histochemical, histological and immunocytochemical methods, organisation of the autonomic nerve structures in small intestine of chinchilla was investigated. Myenteric plexus was localised between circular and longitudinal layers of the smooth muscles. Forming network nodes, the small autonomic, cholinergic ganglia were linked with the bundles of nerve fibres. Adrenergic structures were visible as specific varicose, rosary-like fibres forming bundles of parallel fibres connecting network nodes. Structures of the submucosal plexus formed a finer network than those of the myenteric plexus. Moreover, in 'whole-mount' specimens, fibres forming thick perivascular plexuses were also observed. Immunocytochemical studies confirmed the cholinergic and adrenergic character of the investigated structures. VAChT-positive neurones were found only in myenteric plexus, and numerous VAChT-positive and DBH-positive fibres were found in both plexuses. © 2013 Blackwell Verlag GmbH.

Failure Behaviour of Aluminium/CFRP Laminates with Varying Fibre Orientation in Quasi-static Indentation Test

NASA Astrophysics Data System (ADS)

Romli, N. K.; Rejab, M. R. M.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Salleh, Salwani Mohd; Merzuki, M. N. M.

2018-03-01

The response of the aluminium/carbon laminate was examined by an experimental work. The investigation on fibre metal laminate behaviour was done through an indentation test in a quasi-static loading. The hybrid laminate was fabricated by a compression moulding technique and used two types of carbon fibre orientations; plain weave and unidirectional. The plain weave orientation is dry fibre, and unidirectional orientation is prepreg type fibre. The plain weave carbon fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy while the unidirectional carbon fibre was pressed by using a hot press machine and cured under a specific temperature and pressure. A compression moulding technique was used for the FML fabrication. The aluminium sheet metal has been roughening by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure response of the laminate under five variation of the crosshead speeds in the quasi-static loading. Based on the experimental data of the test, the result of 1 mm/min in the plain weave CFRP has lower loading than unidirectional fibre which the value of both was 4.11 kN and 4.69 kN, respectively.

Optical Coherence Tomography Analysis of the Optic Nerve Head and Surrounding Structures in Long-Duration International Space Station Astronauts.

PubMed

Patel, Nimesh; Pass, Anastas; Mason, Sara; Gibson, Charles R; Otto, Christian

2018-02-01

After long-duration spaceflight, morphological changes in the optic nerve head (ONH) and surrounding tissues have been reported. To develop methods to quantify ONH and surrounding tissue changes using preflight and postflight optical coherence tomographic scans of the ONH region. Two separate analyses were done on retrospective data, with the first comparing a preflight group with a control group, followed by preflight to postflight analysis. All astronaut data were collected on the same instrument and maintained by the National Aeronautics and Space Administration (NASA) Lifetime Surveillance of Astronaut Health. Control data were all collected at the University of Houston. Participants were 15 astronauts who had previously been on an approximately 6-month long-duration mission and had associated preflight and postflight ONH scans. The control group consisted of 43 individuals with no history of ocular pathology or microgravity exposure. Development of algorithms and data analysis were performed between 2012 and 2015. The optical coherence tomography data were analyzed using custom MATLAB programs (MathWorks) in which the Bruch membrane opening (BMO) was manually delineated and used as a reference for all morphological measures. The retinal pigment epithelium (RPE) position 2 mm from the center of the BMO was used to calculate the BMO height. Global and quadrant total retinal thickness and retinal nerve fiber layer (RNFL) thickness were calculated for elliptical annular regions referenced to the BMO. The standard circumpapillary circular scan was used to quantify RNFL and choroidal thickness. Among 15 astronauts (mean [SD] age at preflight evaluation, 48.7 [4.0] years) in this retrospective study, the BMO was recessed in preflight astronauts compared with healthy controls and deepened after long-duration microgravity exposure (median change, -9.9 μm; 95% CI of difference, -16.3 to 3.7 μm; P = .03). After long-duration missions, there was an increase in total retinal thickness to 1000 μm and RNFL to 500 μm from the BMO. Circumpapillary RNFL thickness increased by a median of 2.9 μm (95% CI of difference, 1.1-4.4 μm; P < .01), and there was no change in choroidal thickness (median change, 9.3 μm; 95% CI of difference, -12.1 to 19.6 μm; P = .66). After long-duration microgravity exposure, there are disc edema-like changes in the morphology of the ONH and surrounding tissue. The methods developed to analyze the ONH and surrounding tissue can be useful for assessing longitudinal changes and countermeasures in astronauts, as well as potentially for terrestrial disc edema causes.

Macular Thickness Assessment in Patients with Glaucoma and Its Correlation with Visual Fields

PubMed Central

Vaz, Fernando T; Ramalho, Mário; Pedrosa, Catarina; Lisboa, Maria; Kaku, Paulo; Esperancinha, Florindo

2016-01-01

Aim To determine the relationship between macular thickness (MT) and visual field (VF) parameters, as well as with changes in the retinal nerve fiber layer (RNFL) thickness in patients with glaucoma and ocular hypertension (OH). Materials and methods Cross-sectional statistical analysis of spectral domain optical coherence tomography (SD-OCT) compared with several VF parameters (mean defect - MD and loss variance - LV), in a nonrandom sample of 70 eyes from patients with glaucoma or OH. Statistical analysis was performed using Statistical Package for Social Sciences®. The correlation coefficient used was determined by Spearman correlation and the value of p < 0.05 was considered statistically significant. Results A significant correlation was seen between VF parameters and decrease in MT (MD: r = –0.363, p = 0.002; LV: r=–0.378, p = 0.001). The results were more significant when we compared the LV in the group with average MT 270 to 300 μm (r = –0.413, p = 0.015). Asymmetry between the superior macula and inferior macula correlated with LV (r = 0.432, p = 0.019) in the group with MT < 270 μm. There was also a significant correlation between thinning of superior-temporal and inferior-temporal RNFL and the decrease of the superior and inferior MT respectively (p < 0.001). Conclusion Spectral domain optical coherence tomography measurements of retinal thickness in the macula correlate with VF parameters and RNFL parameters in glaucoma patients. This relationship was first demonstrated with static computerized perimetry made with Octopus 101®. These results can be a valuable aid for evaluating and monitoring of glaucoma patients, establishing a correlation between structure and function. Measurements of retinal thickness in the macula may be an additional instrument for early detection of structural changes and its correlation with functional defects. How to cite this article Mota M, Vaz FT, Ramalho M, Pedrosa C, Lisboa M, Kaku P, Esperancinha F. Macular Thickness Assessment in Patients with Glaucoma and Its Correlation with Visual Fields. J Curr Glaucoma Pract 2016;10(3):85-90. PMID:27857487

Selenium adsorption and speciation with Mg-FeCO₃ layered double hydroxides loaded cellulose fibre.

PubMed

Chen, Ming-Li; An, Myog-Il

2012-06-15

A novel adsorbent was developed by coating Mg-FeCO(3) layered double hydroxides (LDHs) on cellulose fibre. The LDHs take up significant amount of selenite and selenate in a wide pH range with similar sorption capacities (pH 3.8-8.0 for selenite and pH 5.8-7.0 for selenate). A mini-column packed with Mg-FeCO(3) LDHs layer coated cellulose fibre particles was incorporated into a sequential injection system for uptake of selenite at pH 6.0. The retained selenite was afterwards collected with 70 μ L of 0.8%(m/v) NaOH as eluent, followed by hydride generation and atomic fluorescence spectrometric detection. Total inorganic selenium was adsorbed at pH 6.0 by the LDHs-cellulose fibre mini-column after selenate was pre-reduced to selenite by 2.0 mol L(-1) HCl at 80°C, and selenium speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 13.3 was derived with a detection limit of 11 ng L(-1) within a linear range of 0.04-4.0 μg L(-1). A relative standard deviation (RSD) of 3.3% (0.5 μg L(-1), n=11) was achieved. The procedure was validated by analyzing selenium in a certified reference material GBW 10010 (rice), and speciation of inorganic selenium in natural water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Heterogeneous targeting of centrifugal inputs to the glomerular layer of the main olfactory bulb.

PubMed

Gómez, C; Briñón, J G; Barbado, M V; Weruaga, E; Valero, J; Alonso, J R

2005-06-01

The centrifugal systems innervating the olfactory bulb are important elements in the functional regulation of the olfactory pathway. In this study, the selective innervation of specific glomeruli by serotonergic, noradrenergic and cholinergic centrifugal axons was analyzed. Thus, the morphology, distribution and density of positive axons were studied in the glomerular layer of the main olfactory bulb of the rat, using serotonin-, serotonin transporter- and dopamine-beta-hydroxylase-immunohistochemistry and acetylcholinesterase histochemistry in serial sections. Serotonin-, serotonin transporter-immunostaining and acetylcholinesterase-staining revealed a higher heterogeneity in the glomerular layer of the main olfactory bulb than previously reported. In this sense, four types of glomeruli could be identified according to their serotonergic innervation. The main distinctive feature of these four types of glomeruli was their serotonergic fibre density, although they also differed in their size, morphology and relative position throughout the rostro-caudal main olfactory bulb. In this sense, some specific regions of the glomerular layer were occupied by glomeruli with a particular morphology and a characteristic serotonergic innervation pattern that was consistent from animal to animal. Regarding the cholinergic system, we offer a new subclassification of glomeruli based on the distribution of cholinergic fibres in the glomerular structure. Finally, the serotonergic and cholinergic innervation patterns were compared in the glomerular layer. Sexual differences concerning the density of serotonergic fibres were observed in the atypical glomeruli (characterized by their strong cholinergic innervation). The present report provides new data on the heterogeneity of the centrifugal innervation of the glomerular layer that constitutes the morphological substrate supporting the existence of differential modulatory levels among the entire glomerular population.

Effect of the preform fabrication process on the properties of all-silica optical fibres

NASA Astrophysics Data System (ADS)

Grishchenko, A. B.

2017-12-01

In this paper, we present a detailed comparison of technical capabilities of processes for the fabrication of all-silica optical fibre preforms with the use of an atmospheric pressure radio frequency plasma (POVD process) and low-pressure microwave plasma (PCVD process) and analyse the origin of the difference in optical properties between fibres produced by these methods. It is shown that the higher temperature of the core material and the higher oxygen partial pressure in preform fabrication by the POVD process lead to an increase in optical losses in the visible and UV spectral regions in the silica fibres with low hydroxyl (OH) content and a decrease in the solarisation resistance of the fibres with high OH content, i.e. to a more rapid increase in background losses in response to UV irradiation. No such drawbacks are detected in the case of the growth of reflective layers by the PCVD process.

A colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell

NASA Astrophysics Data System (ADS)

Zhang, Zhitao; Guo, Kunping; Li, Yiming; Li, Xueyi; Guan, Guozhen; Li, Houpu; Luo, Yongfeng; Zhao, Fangyuan; Zhang, Qi; Wei, Bin; Pei, Qibing; Peng, Huisheng

2015-04-01

The emergence of wearable electronics and optoelectronics requires the development of devices that are not only highly flexible but can also be woven into textiles to offer a truly integrated solution. Here, we report a colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell (PLEC). The fibre-shaped PLEC is fabricated using all-solution-based processes that can be scaled up for practical applications. The design has a coaxial structure comprising a modified metal wire cathode and a conducting aligned carbon nanotube sheet anode, with an electroluminescent polymer layer sandwiched between them. The fibre shape offers unique and promising advantages. For example, the luminance is independent of viewing angle, the fibre-shaped PLEC can provide a variety of different and tunable colours, it is lightweight, flexible and wearable, and it can potentially be woven into light-emitting clothes for the creation of smart fabrics.

Compression Fracture of CFRP Laminates Containing Stress Intensifications.

PubMed

Leopold, Christian; Schütt, Martin; Liebig, Wilfried V; Philipkowski, Timo; Kürten, Jonas; Schulte, Karl; Fiedler, Bodo

2017-09-05

For brittle fracture behaviour of carbon fibre reinforced plastics (CFRP) under compression, several approaches exist, which describe different mechanisms during failure, especially at stress intensifications. The failure process is not only initiated by the buckling fibres, but a shear driven fibre compressive failure beneficiaries or initiates the formation of fibres into a kink-band. Starting from this kink-band further damage can be detected, which leads to the final failure. The subject of this work is an experimental investigation on the influence of ply thickness and stacking sequence in quasi-isotropic CFRP laminates containing stress intensifications under compression loading. Different effects that influence the compression failure and the role the stacking sequence has on damage development and the resulting compressive strength are identified and discussed. The influence of stress intensifications is investigated in detail at a hole in open hole compression (OHC) tests. A proposed interrupted test approach allows identifying the mechanisms of damage initiation and propagation from the free edge of the hole by causing a distinct damage state and examine it at a precise instant of time during fracture process. Compression after impact (CAI) tests are executed in order to compare the OHC results to a different type of stress intensifications. Unnotched compression tests are carried out for comparison as a reference. With this approach, a more detailed description of the failure mechanisms during the sudden compression failure of CFRP is achieved. By microscopic examination of single plies from various specimens, the different effects that influence the compression failure are identified. First damage of fibres occurs always in 0°-ply. Fibre shear failure leads to local microbuckling and the formation and growth of a kink-band as final failure mechanisms. The formation of a kink-band and finally steady state kinking is shifted to higher compressive strains with decreasing ply thickness. Final failure mode in laminates with stress intensification depends on ply thickness. In thick or inner plies, damage initiates as shear failure and fibre buckling into the drilled hole. The kink-band orientation angle is changing with increasing strain. In outer or thin plies shear failure of single fibres is observed as first damage and the kink-band orientation angle is constant until final failure. Decreasing ply thickness increases the unnotched compressive strength. When stress intensifications are present, the position of the 0°-layer is critical for stability under compression and is thus more important than the ply thickness. Central 0°-layers show best results for OHC and CAI strength due to higher bending stiffness and better supporting effect of the adjacent layers.

Compression Fracture of CFRP Laminates Containing Stress Intensifications

PubMed Central

Schütt, Martin; Philipkowski, Timo; Kürten, Jonas; Schulte, Karl

2017-01-01

For brittle fracture behaviour of carbon fibre reinforced plastics (CFRP) under compression, several approaches exist, which describe different mechanisms during failure, especially at stress intensifications. The failure process is not only initiated by the buckling fibres, but a shear driven fibre compressive failure beneficiaries or initiates the formation of fibres into a kink-band. Starting from this kink-band further damage can be detected, which leads to the final failure. The subject of this work is an experimental investigation on the influence of ply thickness and stacking sequence in quasi-isotropic CFRP laminates containing stress intensifications under compression loading. Different effects that influence the compression failure and the role the stacking sequence has on damage development and the resulting compressive strength are identified and discussed. The influence of stress intensifications is investigated in detail at a hole in open hole compression (OHC) tests. A proposed interrupted test approach allows identifying the mechanisms of damage initiation and propagation from the free edge of the hole by causing a distinct damage state and examine it at a precise instant of time during fracture process. Compression after impact (CAI) tests are executed in order to compare the OHC results to a different type of stress intensifications. Unnotched compression tests are carried out for comparison as a reference. With this approach, a more detailed description of the failure mechanisms during the sudden compression failure of CFRP is achieved. By microscopic examination of single plies from various specimens, the different effects that influence the compression failure are identified. First damage of fibres occurs always in 0°-ply. Fibre shear failure leads to local microbuckling and the formation and growth of a kink-band as final failure mechanisms. The formation of a kink-band and finally steady state kinking is shifted to higher compressive strains with decreasing ply thickness. Final failure mode in laminates with stress intensification depends on ply thickness. In thick or inner plies, damage initiates as shear failure and fibre buckling into the drilled hole. The kink-band orientation angle is changing with increasing strain. In outer or thin plies shear failure of single fibres is observed as first damage and the kink-band orientation angle is constant until final failure. Decreasing ply thickness increases the unnotched compressive strength. When stress intensifications are present, the position of the 0°-layer is critical for stability under compression and is thus more important than the ply thickness. Central 0°-layers show best results for OHC and CAI strength due to higher bending stiffness and better supporting effect of the adjacent layers. PMID:28872623

Numerical modelling of a fibre reflection filter based on a metal–dielectric diffraction structure with an increased optical damage threshold

DOE Office of Scientific and Technical Information (OSTI.GOV)

Terentyev, V S; Simonov, V A

2016-02-28

Numerical modelling demonstrates the possibility of fabricating an all-fibre multibeam two-mirror reflection interferometer based on a metal–dielectric diffraction structure in its front mirror. The calculations were performed using eigenmodes of a double-clad single-mode fibre. The calculation results indicate that, using a metallic layer in the structure of the front mirror of such an interferometer and a diffraction effect, one can reduce the Ohmic loss by a factor of several tens in comparison with a continuous thin metallic film. (laser crystals and braggg ratings)

3D Non-Woven Polyvinylidene Fluoride Scaffolds: Fibre Cross Section and Texturizing Patterns Have Impact on Growth of Mesenchymal Stromal Cells

PubMed Central

Schellenberg, Anne; Ross, Robin; Abagnale, Giulio; Joussen, Sylvia; Schuster, Philipp; Arshi, Annahit; Pallua, Norbert; Jockenhoevel, Stefan; Gries, Thomas; Wagner, Wolfgang

2014-01-01

Several applications in tissue engineering require transplantation of cells embedded in appropriate biomaterial scaffolds. Such structures may consist of 3D non-woven fibrous materials whereas little is known about the impact of mesh size, pore architecture and fibre morphology on cellular behavior. In this study, we have developed polyvinylidene fluoride (PVDF) non-woven scaffolds with round, trilobal, or snowflake fibre cross section and different fibre crimp patterns (10, 16, or 28 needles per inch). Human mesenchymal stromal cells (MSCs) from adipose tissue were seeded in parallel on these scaffolds and their growth was compared. Initial cell adhesion during the seeding procedure was higher on non-wovens with round fibres than on those with snowflake or trilobal cross sections. All PVDF non-woven fabrics facilitated cell growth over a time course of 15 days. Interestingly, proliferation was significantly higher on non-wovens with round or trilobal fibres as compared to those with snowflake profile. Furthermore, proliferation increased in a wider, less dense network. Scanning electron microscopy (SEM) revealed that the MSCs aligned along the fibres and formed cellular layers spanning over the pores. 3D PVDF non-woven scaffolds support growth of MSCs, however fibre morphology and mesh size are relevant: proliferation is enhanced by round fibre cross sections and in rather wide-meshed scaffolds. PMID:24728045

Investigation of mechanical dissipation in CO2 laser-drawn fused silica fibres and welds

NASA Astrophysics Data System (ADS)

Heptonstall, Alastair; Barton, Mark; Cantley, Caroline; Cumming, Alan; Cagnoli, Geppo; Hough, James; Jones, Russell; Kumar, Rahul; Martin, Iain; Rowan, Sheila; Torrie, Calum; Zech, Steven

2010-02-01

The planned upgrades to the LIGO gravitational wave detectors include monolithic mirror suspensions to reduce thermal noise. The mirrors will be suspended using CO2 laser-drawn fused silica fibres. We present here measurements of mechanical dissipation in synthetic fused silica fibres drawn using a CO2 laser. The level of dissipation in the surface layer is investigated and is found to be at a similar level to fibres produced using a gas flame. Also presented is a method for examining dissipation at welded interfaces, showing clear evidence of the existence of this loss mechanism which forms an additional component of the total detector thermal noise. Modelling of a typical detector suspension configuration shows that the thermal noise contribution from this loss source will be negligible.

France's State of the Art Distributed Optical Fibre Sensors Qualified for the Monitoring of the French Underground Repository for High Level and Intermediate Level Long Lived Radioactive Wastes.

PubMed

Delepine-Lesoille, Sylvie; Girard, Sylvain; Landolt, Marcel; Bertrand, Johan; Planes, Isabelle; Boukenter, Aziz; Marin, Emmanuel; Humbert, Georges; Leparmentier, Stéphanie; Auguste, Jean-Louis; Ouerdane, Youcef

2017-06-13

This paper presents the state of the art distributed sensing systems, based on optical fibres, developed and qualified for the French Cigéo project, the underground repository for high level and intermediate level long-lived radioactive wastes. Four main parameters, namely strain, temperature, radiation and hydrogen concentration are currently investigated by optical fibre sensors, as well as the tolerances of selected technologies to the unique constraints of the Cigéo's severe environment. Using fluorine-doped silica optical fibre surrounded by a carbon layer and polyimide coating, it is possible to exploit its Raman, Brillouin and Rayleigh scattering signatures to achieve the distributed sensing of the temperature and the strain inside the repository cells of radioactive wastes. Regarding the dose measurement, promising solutions are proposed based on Radiation Induced Attenuation (RIA) responses of sensitive fibres such as the P-doped ones. While for hydrogen measurements, the potential of specialty optical fibres with Pd particles embedded in their silica matrix is currently studied for this gas monitoring through its impact on the fibre Brillouin signature evolution.

Investigations of plasma induced effects on the surface properties of lignocellulosic natural coir fibres

NASA Astrophysics Data System (ADS)

Praveen, K. M.; Thomas, Sabu; Grohens, Yves; Mozetič, Miran; Junkar, Ita; Primc, Gregor; Gorjanc, Marija

2016-04-01

The development of lignocellulosic natural-fibre-reinforced polymers composites are constrained by two limitations: the upper temperature at which the fibre can be processed and the significant differences between the surface energy of the fibre and the polymer matrix. Since the fibres and matrices are chemically different, strong adhesion at their interface is needed for the effective transfer of stress and bond distribution throughout the interface. The present study investigated the plasma induced effects on the surface properties of natural coir fibres. Weakly ionized oxygen plasma was created in two different discharge chambers by an inductively coupled radiofrequency (RF) discharge. The water absorption studies showed an increase of water sorption from 39% to 100%. The morphological study using scanning electron microscopy (SEM) analysis also confirmed the surface changes which were observed after the plasma treatment. The topographic measurements and phase imaging done using atomic force microscopy (AFM) indicated difference in topographic features and etching of coir wall, which points to the removal of the first layer of coir fibre. X-ray photoelectron spectroscopy (XPS) analysis revealed that the oxygen content measured for samples treated at 50 Pa increased from initial 18% to about 32%.

France’s State of the Art Distributed Optical Fibre Sensors Qualified for the Monitoring of the French Underground Repository for High Level and Intermediate Level Long Lived Radioactive Wastes

PubMed Central

Delepine-Lesoille, Sylvie; Girard, Sylvain; Landolt, Marcel; Bertrand, Johan; Planes, Isabelle; Boukenter, Aziz; Marin, Emmanuel; Humbert, Georges; Leparmentier, Stéphanie; Auguste, Jean-Louis; Ouerdane, Youcef

2017-01-01

This paper presents the state of the art distributed sensing systems, based on optical fibres, developed and qualified for the French Cigéo project, the underground repository for high level and intermediate level long-lived radioactive wastes. Four main parameters, namely strain, temperature, radiation and hydrogen concentration are currently investigated by optical fibre sensors, as well as the tolerances of selected technologies to the unique constraints of the Cigéo’s severe environment. Using fluorine-doped silica optical fibre surrounded by a carbon layer and polyimide coating, it is possible to exploit its Raman, Brillouin and Rayleigh scattering signatures to achieve the distributed sensing of the temperature and the strain inside the repository cells of radioactive wastes. Regarding the dose measurement, promising solutions are proposed based on Radiation Induced Attenuation (RIA) responses of sensitive fibres such as the P-doped ones. While for hydrogen measurements, the potential of specialty optical fibres with Pd particles embedded in their silica matrix is currently studied for this gas monitoring through its impact on the fibre Brillouin signature evolution. PMID:28608831

Effect of Different Concentration of Sodium Hydroxide [NaOH] on Kenaf Sandwich Structures

NASA Astrophysics Data System (ADS)

Aziz, M.; Halim, Z.; Othman, M.

2018-01-01

Sandwich panels are structures that made of three layers, low-density core inserted in between thin skin layers. This structures allow the achievement of excellent mechanical performance with low weight, thus this characteristic fulfil requirement to be use in aircraft application. In recent time, sandwich structures have been studied due to it has multifunction properties and lightweight. The aim of this study is to fabricate a composite sandwich structures with biodegradable material for face sheet [skin] where the fibre being treat with different concentration of sodium hydroxide [NaOH] with 10 and 20 hours of soaking time. Kenaf fibre [treated] reinforced epoxy will be used as skins and Nomex honeycomb is chosen to perform as core for this sandwich composite structure. The mechanical properties that are evaluated such as flexural strength and impact energy of kenaf fibre-reinforced epoxy sandwich structures. For flexural test, the optimum flexural strength is 13.4 MPa and impact strength is 18.3 J.

Investigation of low-velocity impact damage in fibre-metal-laminates

NASA Astrophysics Data System (ADS)

Laliberte, Jeremy F.

2002-04-01

Fibre-metal-laminates (FMLs) represent a significant evolution in airframe material technology. This new family of materials combines low density, high strength and excellent damage tolerance through the use of metal layers strengthened with fibre-reinforced polymer layers. When subjected to low-velocity impact these laminates like traditional composites, develop internal delamination damage, matrix cracks and limited fibre fractures. Also, as in traditional composites, this damage is hidden within the laminate. A method for predicting the amount of internal damage would reduce the experimental testing requirements for the certification of new laminates. This thesis describes the development of a modelling methodology that makes use of a new material subroutine based on continuum damage mechanics in the explicit finite-element code LS-DYNA. This subroutine was verified using the experimental data from low-velocity impact tests of various types of GLARE (GLAss REinforced) aluminum laminates, a common type of commercially available fibre-metal-laminate. Static characterization tests were also conducted on GLARE coupons to provide basic property data for the development of the model. These included static tensile tests and double cantilever beam delamination tests. The modelling methodology was used to improve simulations of low-velocity impact on GLARE laminates. The simulations demonstrated that intralaminar damage has a greater effect on the impact response of the panels than interlaminar damage. Parts of this thesis were components of a multi-year collaborative FML Durability Project between Carleton University, Bombardier Aerospace and the National Research Council Canada.

Mesoporosity as a new parameter for understanding tension stress generation in trees.

PubMed

Chang, Shan-Shan; Clair, Bruno; Ruelle, Julien; Beauchêne, Jacques; Di Renzo, Francesco; Quignard, Françoise; Zhao, Guang-Jie; Yamamoto, Hiroyuki; Gril, Joseph

2009-01-01

The mechanism for tree orientation in angiosperms is based on the production of high tensile stress on the upper side of the inclined axis. In many species, the stress level is strongly related to the presence of a peculiar layer, called the G-layer, in the fibre cell wall. The structure of the G-layer has recently been described as a hydrogel thanks to N(2) adsorption-desorption isotherms of supercritically dried samples showing a high mesoporosity (pores size from 2-50 nm). This led us to revisit the concept of the G-layer that had been, until now, only described from anatomical observation. Adsorption isotherms of both normal wood and tension wood have been measured on six tropical species. Measurements show that mesoporosity is high in tension wood with a typical thick G-layer while it is much less with a thinner G-layer, sometimes no more than normal wood. The mesoporosity of tension wood species without a G-layer is as low as in normal wood. Not depending on the amount of pores, the pore size distribution is always centred around 6-12 nm. These results suggest that, among species producing fibres with a G-layer, large structural differences of the G-layer exist between species.

Analysis of various factors affecting pupil size in patients with glaucoma.

PubMed

Park, Ji Woong; Kang, Bong Hui; Kwon, Ji Won; Cho, Kyong Jin

2017-09-16

Pupil size is an important factor in predicting post-operative satisfaction. We assessed the correlation between pupil size, measured by Humphrey static perimetry, and various affecting factors in patients with glaucoma. In total, 825 eyes of 415 patients were evaluated retrospectively. Pupil size was measured with Humphrey static perimetry. Comparisons of pupil size according to the presence of glaucoma were evaluated, as were correlations between pupil size and various factors, including age, logMAR best corrected visual acuity (BCVA), retinal nerve fiber layer (RNFL) thickness, spherical equivalent, intraocular pressure, axial length, central corneal thickness, white-to-white, and the kappa angle. Pupil size was significantly smaller in glaucoma patients than in glaucoma suspects (p < 0.001) or the normal group (p < 0.001). Pupil size decreased significantly as age (p < 0.001) and central cornea thickness (p = 0.007) increased, and increased significantly as logMAR BCVA (p = 0.02) became worse and spherical equivalent (p = 0.007) and RNFL thickness (p = 0.042) increased. In patients older than 50 years, pupil size was significantly larger in eyes with a history of cataract surgery. Humphrey static perimetry can be useful in measuring pupil size. Pupil size was significantly smaller in eyes with glaucoma. Other factors affecting pupil size can be used in a preoperative evaluation when considering cataract surgery or laser refractive surgery.

Comparison of multifocal visual evoked potential, standard automated perimetry and optical coherence tomography in assessing visual pathway in multiple sclerosis patients

PubMed Central

Laron, Michal; Cheng, Han; Zhang, Bin; Schiffman, Jade S.; Tang, Rosa A.; Frishman, Laura J.

2010-01-01

Background Multifocal visual evoked potentials (mfVEP) measure local response amplitude and latency in the field of vision Objective To compare the sensitivity of mfVEP, Humphrey visual field (HVF) and optical coherence tomography (OCT) in detecting visual abnormality in multiple sclerosis (MS) patients. Methods MfVEP, HVF, and OCT (retinal nerve fiber layer [RNFL]) were performed in 47 MS-ON eyes (last optic neuritis (ON) attack ≥ 6 months prior) and 65 MS-no-ON eyes without ON history. Criteria to define an eye as abnormal were: mfVEP 1) amplitude/latency: either amplitude or latency probability plots meeting cluster criteria with 95% specificity 2) amplitude or latency alone (specificity: 97% and 98%, respectively); HVF and OCT, mean deviation and RNFL thickness meeting p < 0.05, respectively. Results MfVEP (amplitude/latency) identified more abnormality in MS-ON eyes (89%) than HVF (72%), OCT (62%), mfVEP amplitude (66%) or latency (67%) alone. 18% of MS-no-ON eyes were abnormal for both mfVEP (amplitude/latency) and HVF compared to 8% with OCT. Agreement between tests ranged from 60% to 79%. MfVEP (amplitude/latency) categorized an additional 15% of MS-ON eyes as abnormal compared to HVF and OCT combined. Conclusions MfVEP, which detects both demyelination (increased latency) and neural degeneration (reduced amplitude) revealed more abnormality than HVF or OCT in MS patients. PMID:20207786

Corneal and Retinal Neuronal Degeneration in Early Stages of Diabetic Retinopathy.

PubMed

Srinivasan, Sangeetha; Dehghani, Cirous; Pritchard, Nicola; Edwards, Katie; Russell, Anthony W; Malik, Rayaz A; Efron, Nathan

2017-12-01

To examine the neuronal structural integrity of cornea and retina as markers for neuronal degeneration in nonproliferative diabetic retinopathy (NPDR). Participants were recruited from the broader Brisbane community, Queensland, Australia. Two hundred forty-one participants (187 with diabetes and 54 nondiabetic controls) were examined. Diabetic retinopathy (DR) was graded according to the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. Corneal nerve fiber length (CNFL), corneal nerve branch density (CNBD), corneal nerve fiber tortuosity (CNFT), full retinal thickness, retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), focal (FLV) and global loss volumes (GLV), hemoglobin A1c (HbA1c), nephropathy, neuropathy, and cardiovascular measures were examined. The central zone (P = 0.174), parafoveal thickness (P = 0.090), perifovea (P = 0.592), RNFL (P = 0.866), GCC (P = 0.798), and GCC GLV (P = 0.338) did not differ significantly between the groups. In comparison to the control group, those with very mild NPDR and those with mild NPDR had significantly higher focal loss in GCC volume (P = 0.036). CNFL was significantly lower in those with mild NPDR (P = 0.004) in comparison to the control group and those with no DR. The CNBD (P = 0.094) and CNFT (P = 0.458) did not differ between the groups. Both corneal and retinal neuronal degeneration may occur in early stages of diabetic retinopathy. Further studies are required to examine these potential markers for neuronal degeneration in the absence of clinical signs of DR.

Evaluation of fracture toughness of ZrO 2 and Si 3N 4 engineering ceramics following CO 2 and fibre laser surface treatment

NASA Astrophysics Data System (ADS)

Shukla, P. P.; Lawrence, J.

2011-02-01

The fracture toughness property ( K1C) of Si 3N 4 and ZrO 2 engineering ceramics was investigated by means of CO 2 and a fibre laser surface treatment. Near surface modifications in the hardness were investigated by employing the Vickers indentation method. Crack lengths and the crack geometry were then measured by using the optical microscopy. A co-ordinate measuring machine was used to investigate the diamond indentations and to measure the lengths of the cracks. Thereafter, computational and analytical methods were employed to determine the K1C. An increase in the K1C of both ceramics was found by the CO 2 and the fibre laser surface treatment in comparison to the as-received surfaces. The K1C of the CO 2 laser radiated surface of the Si 3N 4 was over 3% higher in comparison to that of the fibre laser treated surface. This was by softening of the near surface layer of the Si 3N 4 which comprised of lowering of hardness, which in turn increased the crack resistance. The effects were not similar in ZrO 2 ceramic to that of the Si 3N 4 as the fibre laser radiation in this case had produced an increase of 34% compared to that of the CO 2 laser radiation. This occurred due to propagation of lower crack resulting from the Vickers indentation test during the fibre laser surface treatment which inherently affected the end K1C through an induced compressive stress layer. The K1C modification of the two ceramics treated by the CO 2 and the fibre laser was also believed to be influenced by the different laser wavelength and its absorption co-efficient, the beam delivery system as well as the differences in the brightness of the two lasers used.

Region-specific ischemia, neovascularization and macular oedema in treatment-naïve proliferative diabetic retinopathy.

PubMed

Lange, Jason; Hadziahmetovic, Majda; Zhang, Jingfa; Li, Weiye

2018-02-07

Region-specific pathology in proliferative diabetic retinopathy enhances our understanding and management of this disease. To investigate non-perfusion, neovascularization and macular oedema. A cross-sectional, observational, non-randomized study. Consecutive 43 eyes of 27 treatment-naïve patients. Ultra-widefield fluorescein angiography for studying specific zones, that is, far-peripheral zone, mid-peripheral zone and central retina (cr), and spectral-domain optical coherence tomography for analysing thickness of macular layers. Non-perfusion index (NPI) and neovascularization index (NVI) in different zones, thickness of cr, retinal nerve fibre layer, ganglion cell layer (GCL), inner nuclear layer (INL) and outer plexiform layer in parafoveal regions. The NPI of far-periphery and NVI of mid-periphery were the highest by one-way analysis of variance testing. Ischemic retina defined as high NPI in far-periphery was significantly related to macular oedema via a binary classification approach (P < 0.05). The ischemic retina was correlated with a decreased thickness of both retinal nerve fibre and GCL (P < 0.05); macular oedema was correlated with increased INL thickness (P < 0.0001). The region-specific correlation of NPI of far-periphery and NVI of mid-periphery, but not with central retinal thickness, suggests different pathogeneses of neovascularization and macular oedema. Retinal nerve fibre layer and GCL, both biomarkers of diabetic retinal neuronopathy, are associated with retinal ischemia, but not with macular oedema, suggesting that diabetic microangiopathy and neuronopathy possess distinct pathogenic pathways. The strong correlation between macular oedema and INL indicates that intracellular oedema is a determining factor of diabetic macular oedema. © 2018 Royal Australian and New Zealand College of Ophthalmologists.

Using corneal confocal microscopy to track changes in the corneal layers of dry eye patients after autologous serum treatment.

PubMed

Mahelkova, Gabriela; Jirsova, Katerina; Seidler Stangova, Petra; Palos, Michalis; Vesela, Viera; Fales, Ivan; Jiraskova, Nada; Dotrelova, Dagmar

2017-05-01

In vivo corneal confocal microscopy allows the examination of each layer of the cornea in detail and the identification of pathological changes at the cellular level. The purpose of this study was to identify the possible effects of a three-month treatment with autologous serum eye-drops in different corneal layers of patients with severe dry eye disease using corneal confocal microscopy. Twenty-six patients with dry eye disease were included in the study. Corneal fluorescein staining was performed. The corneas of the right eyes were examined using in vivo corneal confocal microscopy before and after a three-month treatment with autologous serum drops. The densities of superficial and basal epithelial cells, Langerhans cells, the keratocytes and activated keratocytes, the density of endothelial cells and the status of the sub-basal nerve plexus fibres were evaluated. A significant decrease in corneal fluorescein staining was found after the three-month autologous serum treatment (p = 0.0006). The basal epithelial cell density decreased significantly (p = 0.001), while the density of superficial epithelial cells did not change significantly (p = 0.473) nor did the number of Langerhans cells or activated keratocytes (p = 0.223; p = 0.307, respectively). There were no differences in the other corneal cell layers or in the status of the nerve fibres. The results demonstrate the ability of corneal confocal microscopy to evaluate an improvement in the basal epithelial cell layer of the cornea after autologous serum treatment in patients with dry eye disease. More studies with longer follow-up periods are needed to elucidate the suitability of corneal confocal microscopy to follow the effect of autologous serum treatment on nerve fibres or other corneal layers in dry eye disease patients. © 2016 Optometry Australia.

Are endometrial nerve fibres unique to endometriosis? A prospective case-control study of endometrial biopsy as a diagnostic test for endometriosis in women with pelvic pain.

PubMed

Ellett, Lenore; Readman, Emma; Newman, Marsali; McIlwaine, Kate; Villegas, Rocio; Jagasia, Nisha; Maher, Peter

2015-12-01

Can the presence of endometrial nerve fibres be used as a diagnostic test for endometriosis in women with pelvic pain? Endometrial fine nerve fibres were seen in the endometrium of women both with and without endometriosis, making their detection a poor diagnostic tool for endometriosis. Laparoscopy and biopsy are currently the gold standard for making a diagnosis of endometriosis. It has been reported that small density nerve fibres in the functional layer of the endometrium are unique to women with endometriosis and hence nerve fibre detection could function as a less invasive diagnostic test of endometriosis. However, it may be that other painful conditions of the pelvis are also associated with these nerve fibres. We therefore focused this prospective study on women with pelvic pain to examine the efficacy of endometrial nerve fibre detection as a diagnostic test for endometriosis. This prospective case-control study conducted between July 2009 and July 2013 included 44 women with pelvic pain undergoing laparoscopic examination for the diagnosis of endometriosis. Immunohistochemical nerve fibre detection in endometrial curettings and biopsies using anti-protein gene product 9.5 was compared with surgical diagnosis. Paired endometrial biopsies and curettings were taken from patients with (n = 22, study group) and without (n = 22, control group) endometriosis. Tissue was analysed by immunohistochemistry and nerve fibres were counted whenever they were present in the functional layer of the endometrium. Fine nerve fibres were present in the eutopic endometrium of patients both with and without endometriosis. The presence of nerve fibres in curettings was not effective for either diagnosing or excluding endometriosis; sensitivity and specificity were 31.8 and 45.5% respectively, positive predictive value was 36.8% and negative predictive value was 40.0%. Few endometrial biopsy specimens were found to have nerve fibres present; sensitivity and specificity for endometrial biopsy were 13.6 and 68.2% respectively, positive predictive value was 30.0% and negative predictive value was 44.1%. This was a relatively small sample size and studies like this are subject to the heterogeneous nature of the patient population and tissue samples, despite our best efforts to regulate these parameters. Our results demonstrate that fine nerve fibres are present in women with and without endometriosis. Future work should focus on the function of endometrial nerves and whether these nerves are involved with the subfertility or pain that endometriosis sufferers experience. Our study does not support the detection of endometrial nerve fibres as a non-invasive diagnostic test of endometriosis in women with pelvic pain. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Structure of the Elastin-Contractile Units in the Thoracic Aorta and How Genes That Cause Thoracic Aortic Aneurysms and Dissections Disrupt This Structure.

PubMed

Karimi, Ashkan; Milewicz, Dianna M

2016-01-01

The medial layer of the aorta confers elasticity and strength to the aortic wall and is composed of alternating layers of smooth muscle cells (SMCs) and elastic fibres. The SMC elastin-contractile unit is a structural unit that links the elastin fibres to the SMCs and is characterized by the following: (1) layers of elastin fibres that are surrounded by microfibrils; (2) microfibrils that bind to the integrin receptors in focal adhesions on the cell surface of the SMCs; and (3) SMC contractile filaments that are linked to the focal adhesions on the inner side of the membrane. The genes that are altered to cause thoracic aortic aneurysms and aortic dissections encode proteins involved in the structure or function of the SMC elastin-contractile unit. Included in this gene list are the genes encoding protein that are structural components of elastin fibres and microfibrils, FBN1, MFAP5, ELN, and FBLN4. Also included are genes that encode structural proteins in the SMC contractile unit, including ACTA2, which encodes SMC-specific α-actin and MYH11, which encodes SMC-specific myosin heavy chain, along with MYLK and PRKG1, which encode kinases that control SMC contraction. Finally, mutations in the gene encoding the protein linking integrin receptors to the contractile filaments, FLNA, also predispose to thoracic aortic disease. Thus, these data suggest that functional SMC elastin-contractile units are important for maintaining the structural integrity of the aorta. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Microplastics in the Baltic Sea water: fibers everywhere.

NASA Astrophysics Data System (ADS)

Khatmullina, Lilia; Bagaev, Andrey; Chubarenko, Irina

2017-04-01

Presence of thin synthetic fibres (microfibres, tens of micrometres in diameter) in the surface waters and sediments is documented in different studies; however, the data on their exact abundances in the marine environment are commonly not presented owing to the shortcomings of the sampling procedure and general absence of well-established methodology for microplastics data collection. Nevertheless, we made an attempt to qualitatively analyse the amounts of microplastic fibres in the water column of the Baltic Sea. Water samples acquired during 6 cruises over the Baltic Sea Proper in 2015-2016 were filtered using 174 μm filters, which were subsequently analysed by microscope. From the total of 95 examined filters, 63% contained fibres. They were identified by colour and the reaction to the mechanical action of a thin needle: justification of anthropogenic origin was considered to be enough; any questionable objects were discarded. Fibres comprise more than 90% of the whole microplastic particles found in the near-bottom layers in the coastal zone and around 24% of microplastics in the surface and intermediate waters, with mean concentrations of 0.71 and 0.07 fibres per litre, respectively. Although the methodology still requires a lot of enhancement, even the preliminary results indicate ubiquitous distribution of the microfibres in the water column of the Baltic Sea with surface and bottom layers revealing higher abundances of microfibres in comparison with intermediate layers, and open-sea waters being less contaminated than the coastal ones. Apart from enhancing the sampling technics, we consider that it is crucial to understand principal physical features of fibers behavior in the marine environment (e.g., settling, entrainment by currents), as it would provide an opportunity to parameterize their transport and further on to model distribution of fibers in the water column. The research is supported by the Russian Science Foundation grant number 15-17-10020.

Spider Silk Spun and Integrated into Composites

DTIC Science & Technology

2009-02-20

and elongation of sericin is lower than those of fibroin and, finally, (0 local shear damage is dominant in damaged sericin between fibres, while the... sericin at fibre-joint often shows microflow. These analytical studies are presently being expanded to include synthetic composites made of both...with sericin . Such a cocoon consists of three main parts: an outermost loose mesh structure, the middle shell layers and the innermost tetelette; all

Nonlinear solid finite element analysis of mitral valves with heterogeneous leaflet layers

NASA Astrophysics Data System (ADS)

Prot, V.; Skallerud, B.

2009-02-01

An incompressible transversely isotropic hyperelastic material for solid finite element analysis of a porcine mitral valve response is described. The material model implementation is checked in single element tests and compared with a membrane implementation in an out-of-plane loading test to study how the layered structures modify the stress response for a simple geometry. Three different collagen layer arrangements are used in finite element analysis of the mitral valve. When the leaflets are arranged in two layers with the collagen on the ventricular side, the stress in the fibre direction through the thickness in the central part of the anterior leaflet is homogenized and the peak stress is reduced. A simulation using membrane elements is also carried out for comparison with the solid finite element results. Compared to echocardiographic measurements, the finite element models bulge too much in the left atrium. This may be due to evidence of active muscle fibres in some parts of the anterior leaflet, whereas our constitutive modelling is based on passive material.

The effect of fibre loading and graphene on the mechanical properties of goat hair fibre epoxy composite

NASA Astrophysics Data System (ADS)

Jayaseelan, J.; Vijayakumar, K. R.; Ethiraj, N.; Sivabalan, T.; nallayan, W. Andrew

2017-12-01

Composite materials are heterogenous materials containing one or more solid phases. In recent years cost-effective composite making is an ideal task. Hence we have come out with a natural fibre composite, which contains goat hair and epoxy as a binding element, with the combination of Graphene as a main source of enhanced mechanical property. Fabrication of natural composite consists of five layers of goat hair sandwiched in epoxy matrix. These composites made are tested for mechanical properties including Tensile strength, Flexural strength, Inter laminar shear and Impact strength. The mechanical properties of the six composite sets are analyzed and reported.

CO2 sensing properties of electro-spun Ca-doped ZnO fibres.

PubMed

Pantò, Fabiola; Leonardi, Salvatore Gianluca; Fazio, Enza; Frontera, Patrizia; Bonavita, Anna; Neri, Giovanni; Antonucci, Pierluigi; Neri, Fortunato; Santangelo, Saveria

2018-07-27

The availability of low-cost, high-performing sensors for carbon dioxide detection in the environment may play a crucial role for reducing CO 2 emissions and limiting global warming. In this study, calcium-doped zinc oxide nanofibres with different Ca to Zn loading ratios (1:40 or 1:20) are synthesised via electro-spinning, thoroughly characterised and, for the first time, tested as an active material for the detection of carbon dioxide. The results of their characterisation show that the highly porous fibres consist of interconnected grains of oxide with the hexagonal wurtzite structure of zincite. Depending on the Ca:Zn loading ratio, calcium fully or partly segregates to form calcite on the fibre surface. The high response of the sensor based on the fibres with the highest Ca-doping level can be attributed to the synergy between the fibre morphology and the basicity of Ca-ion sites, which favour the diffusion of the gas molecules within the sensing layer and the CO 2 adsorption, respectively.

Automated choroid segmentation based on gradual intensity distance in HD-OCT images.

PubMed

Chen, Qiang; Fan, Wen; Niu, Sijie; Shi, Jiajia; Shen, Honglie; Yuan, Songtao

2015-04-06

The choroid is an important structure of the eye and plays a vital role in the pathology of retinal diseases. This paper presents an automated choroid segmentation method for high-definition optical coherence tomography (HD-OCT) images, including Bruch's membrane (BM) segmentation and choroidal-scleral interface (CSI) segmentation. An improved retinal nerve fiber layer (RNFL) complex removal algorithm is presented to segment BM by considering the structure characteristics of retinal layers. By analyzing the characteristics of CSI boundaries, we present a novel algorithm to generate a gradual intensity distance image. Then an improved 2-D graph search method with curve smooth constraints is used to obtain the CSI segmentation. Experimental results with 212 HD-OCT images from 110 eyes in 66 patients demonstrate that the proposed method can achieve high segmentation accuracy. The mean choroid thickness difference and overlap ratio between our proposed method and outlines drawn by experts was 6.72µm and 85.04%, respectively.

Autonomic innervation of the muscles in the wall of the bladder and proximal urethra of male rats.

PubMed Central

Watanabe, H; Yamamoto, T Y

1979-01-01

The muscular coat of the body of the rat bladder is innervated almost exclusively by cholinergic endings:adrenergic endings are rare. In the inner longitudinal muscle layer of the proximal urethra, 53% of 310 autonomic nerve endings observed in close relation to the smooth muscle cells were adrenergic and the remaining 47% cholinergic. The middle circular muscle layer of the proximal urethra was innervated predominantly by adrenergic endings: in this layer 86% of the total of 335 endings examined wre regarded as adrenergic. A similar predominantly adrenergic innervation was noted in the outer longitudinal layer of the proximal urethra. A number of striated muscle fibres arose from the outermost striated muscle layer of the proximal urethra and intruded deeply into the outer and middle smooth muscle layers. These intruding striated muscle fibres also received direct autonomic (mostly adrenergic) innervation. The significance of these findings in relation to the physiology of the lower urinary tracts is discussed. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 PMID:489473

Magneto-mechanical bone growth stimulation by actuation of highly porous ferromagnetic fiber arrays

NASA Astrophysics Data System (ADS)

Markaki, Athina E.; Clyne, Trevor W.

2005-02-01

This work relates to porous material made by bonding together fibres of a magnetic material. When subjected to a magnetic field, the array deforms, with individual fibres becoming magnetised along their length and then tending to line up locally with the direction of the field. An investigation is presented into the concept that this deformation could induce beneficial strains in bone tissue network in the early stages of growth as it grows into the porous fibre array. An analytical model has been developed, based on the deflection of individual fibre segments (between joints) experiencing bending moments as a result of the induced magnetic dipole. The model has been validated via measurements made on simple fibre assemblies and random fibre arrays. Work has also been done on the deformation characteristics of random fibre arrays with a matrix filling the inter-fibre space. This has the effect of reducing the fibre deflections. The extent of this reduction, and an estimate of the maximum strains induced in the space-filling material, can be obtained using a simple force balance approach. Predictions indicate that in-growing bone tissue, with a stiffness of around 0.01-0.1 GPa, could be strained to beneficial levels (~1 millistrain), using magnetic field strengths in current diagnostic use (~1 Tesla), provided the fibre segment aspect ratio is at least about 10. Such material has a low Young"s modulus, but the overall stiffness of a prosthesis could be matched to that of cortical bone by using an integrated design involving a porous magneto-active layer bonded to a dense non-magnetic core.

Effect of collagen fibre orientation on intervertebral disc torsion mechanics.

PubMed

Yang, Bo; O'Connell, Grace D

2017-12-01

The intervertebral disc is a complex fibro-cartilaginous material, consisting of a pressurized nucleus pulposus surrounded by the annulus fibrosus, which has an angle-ply structure. Disc injury and degeneration are noted by significant changes in tissue structure and function, which significantly alters stress distribution and disc joint stiffness. Differences in fibre orientation are thought to contribute to changes in disc torsion mechanics. Therefore, the objective of this study was to evaluate the effect of collagen fibre orientation on internal disc mechanics under compression combined with axial rotation. We developed and validated a finite element model (FEM) to delineate changes in disc mechanics due to fibre orientation from differences in material properties. FEM simulations were performed with fibres oriented at [Formula: see text] throughout the disc (uniform by region and fibre layer). The initial model was validated by published experimental results for two load conditions, including [Formula: see text] axial compression and [Formula: see text] axial rotation. Once validated, fibre orientation was rotated by [Formula: see text] or [Formula: see text] towards the horizontal plane, resulting in a decrease in disc joint torsional stiffness. Furthermore, we observed that axial rotation caused a sinusoidal change in disc height and radial bulge, which may be beneficial for nutrient transport. In conclusion, including anatomically relevant fibre angles in disc joint FEMs is important for understanding stress distribution throughout the disc and will be important for understanding potential causes for disc injury. Future models will include regional differences in fibre orientation to better represent the fibre architecture of the native disc.

Modelling the effect of the physical and chemical characteristics of the materials used as casing layers on the production parameters of Agaricus bisporus.

PubMed

Pardo, Arturo; Emilio Pardo, J; de Juan, J Arturo; Zied, Diego Cunha

2010-12-01

The aim of this research was to show the mathematical data obtained through the correlations found between the physical and chemical characteristics of casing layers and the final mushrooms' properties. For this purpose, 8 casing layers were used: soil, soil + peat moss, soil + black peat, soil + composted pine bark, soil + coconut fibre pith, soil + wood fibre, soil + composted vine shoots and, finally, the casing of La Rioja subjected to the ruffling practice. The conclusion that interplays in the fructification process with only the physical and chemical characteristics of casing are complicated was drawn. The mathematical data obtained in earliness could be explained in non-ruffled cultivation. The variability observed for the mushroom weight and the mushroom diameter variables could be explained in both ruffled and non-ruffled cultivations. Finally, the properties of the final quality of mushrooms were established by regression analysis.

Development of a Beam Trajectory Monitoring System Using e+/e- Pair Production Events

NASA Astrophysics Data System (ADS)

Kimura, Shota; Emoto, Yusaku; Fujihara, Kento; Ito, Hiroshi; Kawai, Hideyuki; Kobayashi, Atsushi; Mizuno, Takahiro

2018-01-01

In particle therapy, it is important to monitor the Bragg-peak position. It was simulated by GEANT4 Monte Carlo Simulation Code that the distribution of secondary generated gamma rays on the carbon beam therapy and the proton beam therapy. This simulation shows that gamma rays whose energy is 10 MeV or more are intensively generated at the Bragg-peak position. We are developing the system to monitor the Bragg-peak position which can measure pair production events occurred in the detector by gamma rays from irradiation points. The momentum direction of the gamma ray can be determined by measuring passing points and energy of e+ and e- generated by pair production. This system has 5 parts. The first is the conversion part. This part consists of several layers. Each layer is composed of a La-GPS ((Gd0.75La0.24Ce0.01)2Si2O7) scintillator plate and wavelength-shifting fibre (WLSF) sheets. The scintillator plate is sandwiched between sheets, where the directions of the sheets are in orthogonally x and y directions. In this part, gamma rays are converted to e+ e- pairs and the position where the conversion occured is determined. The second is the tracking part. This part consists of 2 layers of scintillating fibre tracker. Each layer has 6 scintillating fibre sheets for x, x', u, u', v, and v'. The third is the energy measurement part. It measures the energy of e+ and e- by scintillator array and Silicon Photomultipliers. The fourth is the veto counter for bremsstrahlung gamma rays from e+ and e-. The fifth is the beam monitor. By experiment, the number of photoelectrons of La-GPS with a WLSF (B-3(300)MJ, Kuraray) sheet and scintillating fibre (SCSF-78, Kuraray) when charged particle passed was measured as 9.7 and 7.6 respectively.

Influence of fibre distribution and grain size on the mechanical behaviour of friction stir processed Mg–C composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mertens, A., E-mail: anne.mertens@ulg.ac.be; Simar, A.; Adrien, J.

Short C fibres–Mg matrix composites have been produced by friction stir processing sandwiches made of a layer of C fabric stacked between two sheets of Mg alloy AZ31B or AZ91D. This novel processing technique can allow the easy production of large-scale metal matrix composites. The paper investigates the microstructure of FSPed C fibre–Mg composites in relation with the fragmentation of the C fibres during FSP and their influence on the tensile properties. 3D X-ray tomography reveals that the fibres orient like onion rings and are more or less fragmented depending on the local shear stress during the process. The fibremore » volume fraction can be increased from 2.3% to 7.1% by reducing the nugget volume, i.e. by using a higher advancing speed in AZ31B alloy or a stronger matrix alloy, like AZ91D alloy. A higher fibre volume fraction leads to a smaller grain size which brings about an increase of the composite yield strength by 15 to 25%. However, a higher fibre volume fraction also leads to a lower fracture strain. Fracture surface observations reveal that damage occurs by fibre/matrix decohesion along fibres oriented perpendicularly to the loading direction. - Graphical abstract: Display Omitted - Highlights: • C–Mg MMCs were produced by FSP sandwiches made of a C fabric between Mg sheets. • Fibre fragmentation and erosion is larger when the temperature reached during FSP is lower. • A lower advancing speed brings a lower fibre volume fraction and a lower grain size. • X-ray tomography reveals that fibres orient along the FSP material flow. • The fibres and grain size reduction increase the yield strength by 15 to 25%.« less

Can plant-based natural flax replace mineral-based basalt and synthetic E-glass for fibre reinforced polymer tubular energy absorbers? A comparative study on quasi-static axial crushing

NASA Astrophysics Data System (ADS)

Yan, Libo; Wang, Bo; Kasal, Bohumil

2017-12-01

Using plant-based natural fibres to substitute glass fibres as reinforcement of composite materials is of particular interest due to their economic, technical and environmental significance. One potential application of plant-based natural fibre reinforced polymer (FRP) composites is in automotive engineering as crushable energy absorbers. Current study experimentally investigated and compared the energy absorption efficiency of plant-based natural flax, mineral-based basalt and glass FRP composite tubular energy absorbers subjected to quasi-static axial crushing. The effects of number of flax fabric layer, the use of foam-filler and the type of fibre materials on the crashworthiness characteristics and energy absorption capacities were discussed. In addition, the failure mechanisms of the hollow and foam-filled flax, basalt and glass FRP tubes in quasi-static axial crushing were analysed and compared. The test results showed that the energy absorption capabilities of both hollow and foam-filled energy absorbers made of flax were superior to the corresponding energy absorbers made of basalt and were close to energy absorbers made of glass. This study therefore indicated that flax fibre has the great potential to be suitable replacement of basalt and glass fibres for crushable energy absorber application.

Diagnostic Capability of Peripapillary Retinal Volume Measurements in Glaucoma

PubMed Central

Simavli, Huseyin; Poon, Linda Yi-Chieh; Que, Christian John; Liu, Yingna; Akduman, Mustafa; Tsikata, Edem; de Boer, Johannes F.; Chen, Teresa C.

2017-01-01

Purpose To determine the diagnostic capability of spectral domain optical coherence tomography (SD-OCT) peripapillary retinal volume (RV) measurements. Materials and Methods A total of 156 patients, 89 primary open angle (POAG) and 67 normal subjects, were recruited. SD-OCT peripapillary RV was calculated for four quadrants using 3 annuli of varying scan circle diameters: outer circumpapillary annuli of circular grids 1, 2, and 3 (OCA1, OCA2, OCA3). Area under the receiver operating characteristic (AUROC) curves and pairwise comparisons of receiver operating characteristic (ROC) curves were performed to determine which quadrants were best for diagnosing POAG. The pairwise comparisons of the best ROC curves for RV and RNFL were performed. The artifact rates were analyzed. Results Pairwise comparisons showed that the smaller annuli OCA1 and OCA2 had better diagnostic performance than the largest annulus OCA3 (p<0.05 for all quadrants). OCA1 and OCA2 had similar diagnostic performance, except for the inferior quadrant which was better for OCA1 (p=0.0033).The pairwise comparisons of the best ROC curves for RV and RNFL were not statistically significant. Retinal volume measurements had lower rates of artifacts at 7.4% while RNFL measurements had higher rates at 42.9%. Conclusion Peripapillary RV measurements have excellent ability for diagnosing not only glaucoma patients but also a subset of early glaucoma patients. The inferior quadrant of peripapillary annulus OCA1 demonstrated the best diagnostic capability for both glaucoma and early glaucoma. The diagnostic ability of RV is comparable to that of RNFL parameters in glaucoma but with lower artifact rates. PMID:28079657

Tie-fibre structure and organization in the knee menisci

PubMed Central

Andrews, Stephen H J; Rattner, Jerome B; Abusara, Ziad; Adesida, Adetola; Shrive, Nigel G; Ronsky, Janet L

2014-01-01

The collagenous structure of the knee menisci is integral to the mechanical integrity of the tissue and the knee joint. The tie-fibre structure of the tissue has largely been neglected, despite previous studies demonstrating its correlation with radial stiffness. This study has evaluated the structure of the tie-fibres of bovine menisci using 2D and 3D microscopy techniques. Standard collagen and proteoglycan (PG) staining and 2D light microscopy techniques were conducted. For the first time, the collagenous structure of the menisci was evaluated using 3D, second harmonic generation (SHG) microscopy. This technique facilitated the imaging of collagen structure in thick sections (50–100 μm). Imaging identified that tie-fibres of the menisci arborize from the outer margin of the meniscus toward the inner tip. This arborization is associated with the structural arrangement of the circumferential fibres. SHG microscopy has definitively demonstrated the 3D organization of tie-fibres in both sheets and bundles. The hierarchy of the structure is related to the organization of circumferential fascicles. Large tie-fibre sheets bifurcate into smaller sheets to surround circumferential fascicles of decreasing size. The tie-fibres emanate from the lamellar layer that appears to surround the entire meniscus. At the tibial and femoral surfaces these tie-fibre sheets branch perpendicularly into the meniscal body. The relationship between tie-fibres and blood vessels in the menisci was also observed in this study. Tie-fibre sheets surround the blood vessels and an associated PG-rich region. This subunit of the menisci has not previously been described. The size of tie-fibre sheets surrounding the vessels appeared to be associated with the size of blood vessel. These structural findings have implications in understanding the mechanics of the menisci. Further, refinement of the complex structure of the tie-fibres is important in understanding the consequences of injury and disease in the menisci. The framework of meniscus architecture also defines benchmarks for the development of tissue-engineered replacements in the future. PMID:24617800

Enhanced all-optical modulation in a graphene-coated fibre with low insertion loss

PubMed Central

Zhang, Haojie; Healy, Noel; Shen, Li; Huang, Chung Che; Hewak, Daniel W.; Peacock, Anna C.

2016-01-01

Graphene is a highly versatile two-dimensional material platform that offers exceptional optical and electrical properties. Of these, its dynamic conductivity and low effective carrier mass are of particular interest for optoelectronic applications as they underpin the material’s broadband nonlinear optical absorption and ultra-fast carrier mobility, respectively. In this paper, we utilize these phenomena to demonstrate a high-speed, in-fibre optical modulator developed on a side-polished optical fibre platform. An especially low insertion loss (<1 dB) was achieved by polishing the fibre to a near atomically smooth surface (<1 nm RMS), which minimized scattering and ensured excellent contact between the graphene film and the fibre. In order to enhance the light-matter interaction, the graphene film is coated with a high index polyvinyl butyral layer, which has the added advantage of acting as a barrier to the surrounding environment. Using this innovative approach, we have fabricated a robust and stable all-fibre device with an extinction ratio as high as 9 dB and operation bandwidth of 0.5 THz. These results represent a key step towards the integration of low-dimensional materials within standard telecoms networks. PMID:27001353

Internal retinal layer thickness and macular migration after internal limiting membrane peeling in macular hole surgery.

PubMed

Faria, Mun Y; Ferreira, Nuno P; Mano, Sofia; Cristóvao, Diana M; Sousa, David C; Monteiro-Grillo, Manuel E

2018-05-01

To provide a spectral-domain optical coherence tomography (SD-OCT)-based analysis of retinal layers thickness and nasal displacement of closed macular hole after internal limiting membrane peeling in macular hole surgery. In this nonrandomized prospective interventional study, 36 eyes of 32 patients were subjected to pars plana vitrectomy and 3.5 mm diameter internal limiting membrane (ILM) peeling for idiopathic macular hole (IMH). Nasal and temporal internal retinal layer thickness were assessed with SD-OCT. Each scan included optic disc border so that distance between optic disc border and fovea were measured. Thirty-six eyes had a successful surgery with macular hole closure. Total nasal retinal thickening (p<0.001) and total temporal retinal thinning (p<0.0001) were observed. Outer retinal layers increased thickness after surgery (nasal p<0.05 and temporal p<0.01). Middle part of inner retinal layers (mIRL) had nasal thickening (p<0.001) and temporal thinning (p<0.05). The mIRL was obtained by deducting ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL) thickness from overall thickness of the inner retinal layer. Papillofoveal distance was shorter after ILM peeling in macular hole surgery (3,651 ± 323 μm preoperatively and 3,361 ± 279 μm at 6 months; p<0.0001). Internal limiting membrane peel is associated with important alteration in inner retinal layer architecture, with thickening of mIRL and shortening of papillofoveal distance. These factors may contribute to recovery of disrupted foveal photoreceptor and vision improvement after IMH closure.

Optic Nerve Head Development in Healthy Infants and Children Using Handheld Spectral-Domain Optical Coherence Tomography.

PubMed

Patel, Aarti; Purohit, Ravi; Lee, Helena; Sheth, Viral; Maconachie, Gail; Papageorgiou, Eleni; McLean, Rebecca J; Gottlob, Irene; Proudlock, Frank A

2016-10-01

To determine feasibility of optic nerve head (ONH) imaging and to characterize ONH development in full-term infants without sedation using handheld spectral-domain optical coherence tomography (SD OCT). Prospective cross-sectional study. Three hundred fifty-two children aged between 1 day and 13 years. All participants were imaged using handheld SD OCT without sedation during a single scan session. The percentage of successful scans was calculated. Interexaminer reproducibility and differences between right and left eyes were assessed using intraclass correlation coefficients (ICCs). Images were analyzed using ImageJ software. The developmental trajectories over time for ONH parameters were calculated using fractional polynomial modelling. Disc and cup diameter (expressed as distance in micrometers and visual angle in degrees), cup depth, Bruch's membrane opening-minimum rim width (BMO-MRW), retinal thickness, and retinal nerve fiber layer (RNFL; 1700 μm and 6° from the disc center). On average, 70% of participants were imaged successfully. Interexaminer reliability was excellent (ICC, >0.89) for diametric and retinal thickness parameters. Right and left eyes were similar for diametric measurements (ICC, >0.79), but more variable for nasal BMO-MRW, RNFL, and retinal thickness. The mean disc and cup diameter increase by 30% and 40%, respectively, between birth and 13 years of age when expressed as a distance measure, but remained constant (at 5°-5.5° and 2°, respectively) when expressed as a visual angle with reference to the eye nodal point. The peripapillary temporal RNFL demonstrated a marked initial decrease of nearly 35% between birth and approximately 18 months of age. This was followed by a slow increase up to 12 years of age when measured at 1700 μm from the disc center, although there was little change when measured at 6° from the disc center. We demonstrated feasibility of handheld SD OCT imaging of the ONH in full-term infants and children without anaesthesia or sedation. This is the first in vivo handheld SD OCT study to describe the development of ONH parameters during the critical early years of visual maturation. Our results provide a normative database for use in routine practice and further studies of ONH pathologic features. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Effect of spectrum bias on the diagnostic accuracy of spectral-domain optical coherence tomography in glaucoma.

PubMed

Rao, Harsha L; Kumbar, Tukaram; Addepalli, Uday K; Bharti, Neha; Senthil, Sirisha; Choudhari, Nikhil S; Garudadri, Chandra S

2012-02-29

To evaluate the influence of a control group on the diagnostic accuracy of spectral-domain optical coherence tomography (SD-OCT) in early glaucoma. In a diagnostic, case-control study, 119 eyes of 60 normal subjects with no findings suspicious for glaucoma (control cohort 1); 76 eyes of 41 subjects referred by general ophthalmologists as glaucoma suspects based on optic disc morphology, but found by glaucoma experts to be normal but with physiological variations in their optic nerves (control cohort 2); and 65 eyes of 46 early-glaucoma patients (cases) underwent imaging of the optic nerve head (ONH), retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) by SD-OCT. Areas under the receiver operating characteristic curves (AUC) of ONH parameters discriminating glaucomatous eyes from normal eyes of control cohort 2 were significantly lesser (P < 0.001) than those discriminating glaucomatous eyes from normal eyes of control cohort 1. AUCs of RNFL parameters discriminating glaucomatous eyes from normal eyes of control cohorts 2 and 1 were comparable. Although the AUCs of GCC thickness parameters were comparable, AUCs of GCC focal and global loss volume in control cohort 2 (0.684 and 0.671. respectively) were significantly less (P < 0.05) than in control cohort 1 (0.881 and 0.841, respectively). The effectiveness of most SD-OCT parameters in detecting glaucoma significantly decreased when evaluated against a clinically relevant control group with suspicious-looking optic nerves compared with that against a control group consisting of normal subjects with no findings suspicious for glaucoma.

Ocular characteristics associated with the location of focal lamina cribrosa defects in open-angle glaucoma patients.

PubMed

Park, H-Yl; Hwang, Y S; Park, C K

2017-04-01

PurposeTo investigate the clinical characteristics according to the location of focal lamina cribrosa (LC) defects and its associated ocular features.Patients and methodsA total of 139 open-angle glaucoma patients underwent Spectralis optical coherence tomography (OCT) with enhanced depth imaging. Alterations in the contour of the LC were investigated to find focal LC defects. The location of the visible LC defect from the neural canal wall (far-peripheral and mid-peripheral) and clock-hour position (superotemporal, temporal and inferotemporal) were classified. Disc ovality ratio and disc-foveal angle were measured from disc and retinal nerve fiber layer (RNFL) photographs. The disc tilt degree was measured using a Heidelberg Retina Tomograph (HRT) III system. The en face OCT image of the disc scans was registered to the disc and RNFL photographs, to determine whether the focal LC defects corresponded spatially to the glaucomatous damage location.ResultsEyes with far-peripheral LC defects were significantly myopic and had a higher disc ovality ratio. The disc tilt degree obtained by HRT revealed significant temporal disc tilt in eyes with temporal LC defects (P<0.001). Eyes with inferotemporal LC defects had a significantly larger disc-foveal angle (P=0.027). The inferotemporal LC defects corresponded to the location of glaucomatous damage in 81.6%; however, only 46.2% of eyes with a superotemporal LC defect and 3.2% of eyes with a temporal LC defect corresponded spatially with the glaucomatous damage location.ConclusionsThe clinical characteristics and association with glaucomatous damage location were different according to the location of focal LC defect.

Structure-function correlations in glaucoma using matrix and standard automated perimetry versus time-domain and spectral-domain OCT devices.

PubMed

Pinto, Luciano Moreira; Costa, Elaine Fiod; Melo, Luiz Alberto S; Gross, Paula Blasco; Sato, Eduardo Toshio; Almeida, Andrea Pereira; Maia, Andre; Paranhos, Augusto

2014-04-10

We examined the structure-function relationship between two perimetric tests, the frequency doubling technology (FDT) matrix and standard automated perimetry (SAP), and two optical coherence tomography (OCT) devices (time-domain and spectral-domain). This cross-sectional study included 97 eyes from 29 healthy individuals, and 68 individuals with early, moderate, or advanced primary open-angle glaucoma. The correlations between overall and sectorial parameters of retinal nerve fiber layer thickness (RNFL) measured with Stratus and Spectralis OCT, and the visual field sensitivity obtained with FDT matrix and SAP were assessed. The relationship also was evaluated using a previously described linear model. The correlation coefficients for the threshold sensitivity measured with SAP and Stratus OCT ranged from 0.44 to 0.79, and those for Spectralis OCT ranged from 0.30 to 0.75. Regarding FDT matrix, the correlation ranged from 0.40 to 0.79 with Stratus OCT and from 0.39 to 0.79 with Spectralis OCT. Stronger correlations were found in the overall measurements and the arcuate sectors for both visual fields and OCT devices. A linear relationship was observed between FDT matrix sensitivity and the OCT devices. The previously described linear model fit the data from SAP and the OCT devices well, particularly in the inferotemporal sector. The FDT matrix and SAP visual sensitivities were related strongly to the RNFL thickness measured with the Stratus and Spectralis OCT devices, particularly in the overall and arcuate sectors. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Intravitreal erythropoietin injection in late-stage optic neuropathy: a safety study on human.

PubMed

Acar, Ugur; Kucuk, Bekir; Sevinc, Mehmet Koray; Aykas, Seckin; Erdurmus, Mesut; Sobaci, Gungor

2018-06-01

To evaluate the whether intravitreal erythropoietin (EPO) administration has any beneficial or adverse effect in patients with late-stage optic neuropathy (ON) or not. The study examined 16 eyes of 16 patients who had late-stage ON and ≥1/20 best-corrected visual acuity (BCVA) in their affected eye. There were nonarteritic ischemic ON in 10 (62.5%) eyes, traumatic ON in 4 (25.0%) eyes and methanol-induced ON in 2 (12.5%) eyes. Using pars plana approach, 2000 IU/0.2 ml EPO was administered intravitreally with a 30-gauge needle. Injections were administered three times with 6-week intervals. We compared the differences in the BCVA, intraocular pressure (IOP), retinal nerve fiber layer (RNFL) thickness, pattern visual evoked potentials (p-VEP) and pattern electroretinography (p-ERG) parameters performed at initial examination and final visits. The mean age of the patients was 52.38 ± 12.00 years; 2 (12.50%) of them were female, and 14 (87.50%) of them were male. The mean BCVA levels of 16 patients with optic atrophy were 1.12 ± 0.25 logMAR at the initial examination and 1.08 ± 0.26 logMAR at the final visit (p = 0.102). There was no statistically significant difference between the initial and final RNFL thicknesses, IOP values, p-ERG or p-VEP responses. Intravitreal EPO injections have no beneficial or detrimental effect on the late stage of ON. Further studies are necessary to compare our results in patients with ON in earlier stages.

Relationship among visual field, blood flow, and neural structure measurements in glaucoma.

PubMed

Hwang, John C; Konduru, Ranjith; Zhang, Xinbo; Tan, Ou; Francis, Brian A; Varma, Rohit; Sehi, Mitra; Greenfield, David S; Sadda, Srinivas R; Huang, David

2012-05-17

To determine the relationship among visual field, neural structural, and blood flow measurements in glaucoma. Case-control study. Forty-seven eyes of 42 patients with perimetric glaucoma were age-matched with 27 normal eyes of 27 patients. All patients underwent Doppler Fourier-domain optical coherence tomography to measure retinal blood flow and standard glaucoma evaluation with visual field testing and quantitative structural imaging. Linear regression analysis was performed to analyze the relationship among visual field, blood flow, and structure, after all variables were converted to logarithmic decibel scale. Retinal blood flow was reduced in glaucoma eyes compared to normal eyes (P < 0.001). Visual field loss was correlated with both reduced retinal blood flow and structural loss of rim area and retinal nerve fiber layer (RNFL). There was no correlation or paradoxical correlation between blood flow and structure. Multivariate regression analysis revealed that reduced blood flow and structural loss are independent predictors of visual field loss. Each dB decrease in blood flow was associated with at least 1.62 dB loss in mean deviation (P ≤ 0.001), whereas each dB decrease in rim area and RNFL was associated with 1.15 dB and 2.56 dB loss in mean deviation, respectively (P ≤ 0.03). There is a close link between reduced retinal blood flow and visual field loss in glaucoma that is largely independent of structural loss. Further studies are needed to elucidate the causes of the vascular dysfunction and potential avenues for therapeutic intervention. Blood flow measurement may be useful as an independent assessment of glaucoma severity.

Manufacturing and testing of wavefront filters for DARWIN

NASA Astrophysics Data System (ADS)

Flatscher, R.; Artjushenko, V.; Sakharova, T.; Pereira do Carmo, Joao

2017-11-01

Wavefront filtering is mandatory in the realisation of nulling interferometers with high star light suppression capability required to detect extrasolar planets, such as the one foreseen for the ESA Darwin mission. This paper presents the design, manufacturing, and test results of single mode fibres to be used as wavefront filters in mid-infrared range. Fibres made from chalcogenide glass and silver halide crystals were produced. The first class can serve as wavefront filters up to a wavelength of 11 microns, while silver halide fibres can be used over the full Darwin wavelength range from 6.5 to 18 micron. The chalcogenide glass fibres were drawn by double crucible method whereas polycrystalline fibres from silver halides were fabricated by multiple extrusion from a crystalline preform. Multi-layer AR-coatings for fibre ends were developed and environmentally tested for both types of fibres. Special fibre facet polishing procedures were established, in particular for the soft silver halide fibre ends. Cable design and assembly process were also developed, including termination by SMA-connectors with ceramic ferrules and fibre protection by loose PEEK-tubings to prevent excessive bending and chemical attacks for fibres. The wavefront filtering capability of the fibres was demonstrated on a high quality Mach-Zehnder interferometer. Two different groups of laser sources were used to measure the wavefront filtering of the fibres by using a CO-laser for testing in the lower sub-band and a CO2-laser to check the upper sub-band. Measurements of the fibres far field intensity distribution and transmission were performed for numerous cable samples. Single mode behaviour was observed in more than 25 silver halide fibre cables before AR-coating of their ends, while after that 17 cables were compliant with all technical requirements. Residual cladding modes existing in short single mode fibres were effectively removed by applying of a proper absorbing jacket to the fibre's lateral surface and by adding an oversized output aperture in front of fibre ends. Several fibres were exposed to gamma radiation of total dose of 25, 50, and even 500 krad. No deterioration was found on AR-coated fibre ends and on fibre material. Five fibres were irradiated by proton radiation of 10MeV energy and 1010 p/cm2 equivalent fluence. Several fibres were cooled down to 10 K by plunging them in a dipstick into liquid Helium. Silver halide fibres survived that test when cables were properly assembled. The brittle chalcogenide glass fibres were much more sensitive to thermal gradients and the related cables did not survive the thermal shock. Critical issues have been revealed in multiple drawings of chalcogenide glass fibres where core and cladding composition were not stable at some fabrication stages - resulting in a poor single mode guiding. Much better results have been achieved with polycrystalline fibres from silver halides made with a small core and low NA and enabling single mode guiding in the mid infrared.

Spectral-Domain Optical Coherence Tomography for Glaucoma Diagnosis

PubMed Central

Gracitelli, Carolina P.B; Abe, Ricardo Y; Medeiros, Felipe A

2015-01-01

Identification of structural damage to the optic nerve and retinal nerve fiber layer (RNFL) is an essential component of diagnosis and management of glaucoma. The introduction of spectral-domain OCT (SD-OCT) has allowed objective quantification of damage to these structures with unprecedented resolution. In addition, recent attention has been directed towards imaging the macular area for quantifying loss of neural tissue caused by the disease. Many studies have evaluated and compared the diagnostic accuracies of a variety of parameters that can be obtained from imaging these areas of the ocular fundus. In this article, we critically review the existing literature evaluating the diagnostic accuracy of SD-OCT in glaucoma and we discuss issues related to how SD-OCT results should be incorporated into clinical practice. PMID:26069519

Effect of spatial filtering on crosstalk reduction in surface EMG recordings.

PubMed

Mesin, Luca; Smith, Stuart; Hugo, Suzanne; Viljoen, Suretha; Hanekom, Tania

2009-04-01

Increasing the selectivity of the detection system in surface electromyography (EMG) is beneficial in the collection of information of a specific portion of the investigated muscle and to reduce the contribution of undesired components, such as non-propagating components (due to generation or end-of-fibre effects) or crosstalk from nearby muscles. A comparison of the ability of different spatial filters to reduce the amount of crosstalk in surface EMG measurements was conducted in this paper using simulated signals. It focused on the influence of different properties of the muscle anatomy (changing subcutaneous layer thickness, skin conductivity, fibre length) and detection system (single, double and normal double differential, with two inter-electrode distances - IED) on the amount of crosstalk present in the measurements. A cylindrical multilayer (skin, subcutaneous tissue, muscle, bone) analytical model was used to simulate single fibre action potentials (SFAPs). Fibres were grouped together in motor units (MUs) and motor unit action potentials (MUAPs) were obtained by adding the SFAPs of the corresponding fibres. Interference surface EMG signals were obtained, modelling the recruitment of MUs and rate coding. The average rectified value (ARV) and mean frequency (MNF) content of the EMG signals were studied and used as a basis for determining the selectivity of each spatial filter. From these results it was found that the selectivity of each spatial filter varies depending on the transversal location of the measurement electrodes and on the anatomy. An increase in skin conductivity favourably affects the selectivity of normal double differential filters as does an increase in subcutaneous layer thickness. An increase in IED decreases the selectivity of all the analysed filters.

Effect of boron oxide addition on fibre drawing, mechanical properties and dissolution behaviour of phosphate-based glass fibres with fixed 40, 45 and 50 mol% P2O5

PubMed Central

Sharmin, Nusrat; Parsons, Andrew J; Rudd, Chris D

2014-01-01

Previous studies investigating manufacture of phosphate-based glass fibres from glasses fixed with P2O5 content less than 50 mol% showed that continuous manufacture without breakage was very difficult. In this study, nine phosphate-based glass formulations from the system P2O5-CaO-Na2O-MgO-B2O3 were prepared with P2O5 contents fixed at 40, 45 and 50 mol%, where Na2O was replaced by 5 and 10 mol% B2O3 and MgO and CaO were fixed to 24 and 16 mol%, respectively. The effect of B2O3 addition on the fibre drawing, fibre mechanical properties and dissolution behaviour was investigated. It was found that addition of 5 and 10 mol% B2O3 enabled successful drawing of continuous fibres from glasses with phosphate (P2O5) contents fixed at 40, 45 and 50 mol%. The mechanical properties of the fibres were found to significantly increase with increasing B2O3 content. The highest tensile strength (1200 ± 130 MPa) was recorded for 45P2O5-16CaO-5Na2O-24MgO-10B2O3 glass fibres. The fibres were annealed, and a comparison of the mechanical properties and mode of degradation of annealed and non-annealed fibres were investigated. A decrease in tensile strength and an increase in tensile modulus were observed for the annealed fibres. An assessment of the change in mechanical properties of both the annealed and non-annealed fibres was performed in phosphate-buffered saline (PBS) at 37℃ for 28 and 60 days, respectively. Initial loss of mechanical properties due to annealing was found to be recovered with degradation. The B2O3-containing glass fibres were found to degrade at a much slower rate as compared to the non-B2O3-containing fibres. Both annealed and non-annealed fibres exhibited a peeling effect of the fibre's outer layer during degradation. PMID:24939962

Effect of boron oxide addition on fibre drawing, mechanical properties and dissolution behaviour of phosphate-based glass fibres with fixed 40, 45 and 50 mol% P2O5.

PubMed

Sharmin, Nusrat; Parsons, Andrew J; Rudd, Chris D; Ahmed, Ifty

2014-11-01

Previous studies investigating manufacture of phosphate-based glass fibres from glasses fixed with P2O5 content less than 50 mol% showed that continuous manufacture without breakage was very difficult. In this study, nine phosphate-based glass formulations from the system P2O5-CaO-Na2O-MgO-B2O3 were prepared with P2O5 contents fixed at 40, 45 and 50 mol%, where Na2O was replaced by 5 and 10 mol% B2O3 and MgO and CaO were fixed to 24 and 16 mol%, respectively. The effect of B2O3 addition on the fibre drawing, fibre mechanical properties and dissolution behaviour was investigated. It was found that addition of 5 and 10 mol% B2O3 enabled successful drawing of continuous fibres from glasses with phosphate (P2O5) contents fixed at 40, 45 and 50 mol%. The mechanical properties of the fibres were found to significantly increase with increasing B2O3 content. The highest tensile strength (1200 ± 130 MPa) was recorded for 45P2O5-16CaO-5Na2O-24MgO-10B2O3 glass fibres. The fibres were annealed, and a comparison of the mechanical properties and mode of degradation of annealed and non-annealed fibres were investigated. A decrease in tensile strength and an increase in tensile modulus were observed for the annealed fibres. An assessment of the change in mechanical properties of both the annealed and non-annealed fibres was performed in phosphate-buffered saline (PBS) at 37℃ for 28 and 60 days, respectively. Initial loss of mechanical properties due to annealing was found to be recovered with degradation. The B2O3-containing glass fibres were found to degrade at a much slower rate as compared to the non-B2O3-containing fibres. Both annealed and non-annealed fibres exhibited a peeling effect of the fibre's outer layer during degradation. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Highly Strong and Elastic Graphene Fibres Prepared from Universal Graphene Oxide Precursors

PubMed Central

Huang, Guoji; Hou, Chengyi; Shao, Yuanlong; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang; Zhu, Meifang

2014-01-01

Graphene fibres are continuously prepared from universal graphene oxide precursors by a novel hydrogel-assisted spinning method. With assistance of a rolling process, meters of ribbon-like GFs, or GRs with improved conductivity, tensile strength, and a long-range ordered compact layer structure are successfully obtained. Furthermore, we refined our spinning process to obtained elastic GRs with a mixing microstructure and exceptional elasticity, which may provide a platform for electronic skins and wearable electronics, sensors, and energy devices. PMID:24576869

Additive Layer Manufacturing of Biologically Inspired Short Fibre Reinforced Composites

DTIC Science & Technology

2014-03-01

combination.   It   is   frequently   the   determining   factor   for   the   type   of   fracture   mechanism  observed   [9...Thin Solid Films, 1998. 334(1–2): p. 60-64. 56. Cannas, A., Fracture Mechanics and Failure Analysis of Hollow Shaped Fibre GFRP Composites, in ACCIS...architectures inspired by nature for improving the mechanical and functional properties of engineered materials. The study was advanced on two fronts: (1

Failure modes of vacuum plasma spray tungsten coating created on carbon fibre composites under thermal loads

NASA Astrophysics Data System (ADS)

Hirai, T.; Bekris, N.; Coad, J. P.; Grisolia, C.; Linke, J.; Maier, H.; Matthews, G. F.; Philipps, V.; Wessel, E.

2009-07-01

Vacuum plasma spray tungsten (VPS-W) coating created on a carbon fibre reinforced composite (CFC) was tested under two thermal load schemes in the electron beam facility to examine the operation limits and failure modes. In cyclic ELM-like short transient thermal loads, the VPS-W coating was destroyed sub-layer by sub-layer at 0.33 GW/m 2 for 1 ms pulse duration. At longer single pulses, simulating steady-state thermal loads, the coating was destroyed at surface temperatures above 2700 °C by melting of the rhenium containing multilayer at the interface between VPS-W and CFC. The operation limits and failure modes of the VPS-W coating in the thermal load schemes are discussed in detail.

Cholinergic neurons and fibres in the rat visual cortex.

PubMed

Parnavelas, J G; Kelly, W; Franke, E; Eckenstein, F

1986-06-01

Choline acetyltransferase (ChAT), the acetylcholine synthesizing enzyme, was localized immunocytochemically in neurons and fibres in the rat visual cortex using a monoclonal antibody. ChAT-labelled cells were non-pyramidal neurons, primarily of the bipolar form, distributed in layers II through VI but concentrated in layers II & III. Their perikarya contained a large nucleus and a small amount of perinuclear cytoplasm. The somata and dendrites of all labelled cells received Gray's type I and type II synapses. ChAT-stained axons formed a dense and diffuse network throughout the visual cortex and particularly in layer V. Electron microscopy revealed that the great majority formed type II synaptic contacts with dendrites of various sizes, unlabelled non-pyramidal somata and, on a few occasions, with ChAT-labelled cells. However, a very small number of terminals appeared to form type I synaptic contacts. This study describes the morphological organization of the cholinergic system in the visual cortex, the function of which has been under extensive investigation.

Evidence of the late lignification of the G-layer in Simarouba tension wood, to assist understanding how non-G-layer species produce tensile stress.

PubMed

Roussel, Jean-Romain; Clair, Bruno

2015-12-01

To recover verticality after disturbance, angiosperm trees produce 'tension wood' allowing them to bend actively. The driving force of the tension has been shown to take place in the G-layer, a specific unlignified layer of the cell wall observed in most temperate species. However, in tropical rain forests, the G-layer is often absent and the mechanism generating the forces to reorient trees remains unclear. A study was carried out on tilted seedlings, saplings and adult Simarouba amara Aubl. trees-a species known to not produce a G-layer. Microscopic observations were done on sections of normal and tension wood after staining or observed under UV light to assess the presence/absence of lignin. We showed that S. amara produces a cell-wall layer with all of the characteristics typical of G-layers, but that this G-layer can be observed only as a temporary stage of the cell-wall development because it is masked by a late lignification. Being thin and lignified, tension wood fibres cannot be distinguished from normal wood fibres in the mature wood of adult trees. These observations indicate that the mechanism generating the high tensile stress in tension wood is likely to be the same as that in species with a typical G-layer and also in species where the G-layer cannot be observed in mature cells. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effect of degumming time on silkworm silk fibre for biodegradable polymer composites

NASA Astrophysics Data System (ADS)

Ho, Mei-po; Wang, Hao; Lau, Kin-tak

2012-02-01

Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm fibre), animal-based fibre is a kind of sustainable natural materials for making novel composites. Silkworm silk fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing silk fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the silk fibre's properties, making the silk fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah silk are affected by the degumming time due to the change of the fibre structure and fibroin alignment.

Additive manufacturing of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] scaffolds for engineered bone development.

PubMed

Mota, Carlos; Wang, Shen-Yu; Puppi, Dario; Gazzarri, Matteo; Migone, Chiara; Chiellini, Federica; Chen, Guo-Qiang; Chiellini, Emo

2017-01-01

A wide range of poly(hydroxyalkanoate)s (PHAs), a class of biodegradable polyesters produced by various bacteria grown under unbalanced conditions, have been proposed for the fabrication of tissue-engineering scaffolds. In this study, the manufacture of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (or PHBHHx) scaffolds, by means of an additive manufacturing technique based on a computer-controlled wet-spinning system, was investigated. By optimizing the processing parameters, three-dimensional scaffolds with different internal architectures were fabricated, based on a layer-by-layer approach. The resulting scaffolds were characterized by scanning electron microscopy, which showed good control over the fibre alignment and a fully interconnected porous network, with porosity in the range 79-88%, fibre diameter 47-76 µm and pore size 123-789 µm. Moreover, the resulting fibres presented an internal porosity connected to the external fibre surface as a consequence of the phase-inversion process governing the solidification of the polymer solution. Scaffold compressive modulus and yield stress and strain could be varied in a certain range by changing the architectural parameters. Cell-culture experiments employing the MC3T3-E1 murine pre-osteoblast cell line showed good cell proliferation after 21 days of culture. The PHBHHx scaffolds demonstrated promising results in terms of cell differentiation towards an osteoblast phenotype. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

QBeRT: an innovative instrument for qualification of particle beam in real-time

NASA Astrophysics Data System (ADS)

Gallo, G.; Lo Presti, D.; Bonanno, D. L.; Longhitano, F.; Bongiovanni, D. G.; Reito, S.; Randazzo, N.; Leonora, E.; Sipala, V.; Tommasino, F.

2016-11-01

This paper describes an innovative beam diagnostic and monitoring system composed of a position sensitive detector and a residual range detector, based on scintillating optical fiber and on an innovative read-out strategy and reconstruction algorithm. The position sensitive detector consists of four layers of pre-aligned and juxtaposed scintillating fibres arranged to form two identical overlying and orthogonal planes. The 500 μm square section fibres are optically coupled to two Silicon Photomultiplier arrays using a channel reduction system patented by the Istituto Nazionale di Fisica Nucleare. The residual range detector is a stack of sixty parallel layers of the same fibres used in the position detector, each of which is optically coupled to a channel of Silicon Photomultiplier array by wavelength shifting fibres. The sensitive area of the two detectors is 9 × 9 cm2. After being fully characterized at CATANA proton therapy facility, the performance of the prototypes was tested during last year also at TIFPA proton irradiation facility. The unique feature of these detectors is the possibility to work in imaging conditions (e.g. a particle at a time up to 106 particles per second) and in therapy conditions up to 109 particles per second. The combined use of the two detectors, in imaging conditions, as an example of application, allows the particle radiography of an object. In therapy conditions, in particular, the system measures the position, the profiles, the energy and the fluence of the beam.