Image registration reveals central lens thickness minimally increases during accommodation

PubMed Central

Schachar, Ronald A; Mani, Majid; Schachar, Ira H

2017-01-01

Purpose To evaluate anterior chamber depth, central crystalline lens thickness and lens curvature during accommodation. Setting California Retina Associates, El Centro, CA, USA. Design Healthy volunteer, prospective, clinical research swept-source optical coherence biometric image registration study of accommodation. Methods Ten subjects (4 females and 6 males) with an average age of 22.5 years (range: 20–26 years) participated in the study. A 45° beam splitter attached to a Zeiss IOLMaster 700 (Carl Zeiss Meditec Inc., Jena, Germany) biometer enabled simultaneous imaging of the cornea, anterior chamber, entire central crystalline lens and fovea in the dilated right eyes of subjects before, and during focus on a target 11 cm from the cornea. Images with superimposable foveal images, obtained before and during accommodation, that met all of the predetermined alignment criteria were selected for comparison. This registration requirement assured that changes in anterior chamber depth and central lens thickness could be accurately and reliably measured. The lens radii of curvatures were measured with a pixel stick circle. Results Images from only 3 of 10 subjects met the predetermined criteria for registration. Mean anterior chamber depth decreased, −67 μm (range: −0.40 to −110 μm), and mean central lens thickness increased, 117 μm (range: 100–130 μm). The lens surfaces steepened, anterior greater than posterior, while the lens, itself, did not move or shift its position as appeared from the lack of movement of the lens nucleus, during 7.8 diopters of accommodation, (range: 6.6–9.7 diopters). Conclusion Image registration, with stable invariant references for image correspondence, reveals that during accommodation a large increase in lens surface curvatures is associated with only a small increase in central lens thickness and no change in lens position. PMID:28979092

Evaluation of Anterior Segment Parameters in Obesity

PubMed Central

Uzun, Feyzahan; Karaca, Emine Esra; Kalaycı, Mustafa

2015-01-01

Purpose To investigate anterior segment parameters in obese patients in comparison to healthy individuals. Methods Thirty-four obese subjects and 34 age-sex-matched healthy subjects were enrolled in this prospective cross-sectional study. Ophthalmological examinations including intraocular pressure (IOP), central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and axial length (AL) measurements were performed on each subject. Height and weight of all subjects were recorded and body mass index (BMI) was calculated. Results IOP was significantly higher in the obese group (p = 0.003). The mean ACD in obese subjects was significantly lower than that in control subjects (p = 0.036). AL, ACV, ACA and CCT were not significantly different between the groups. There was a positive correlation between BMI and IOP (r = 0.404, p < 0.001). ACD and ACA were negatively correlated with BMI. Conclusions IOP was significantly higher and ACD was significantly lower in obese subjects. AL, ACV, ACA and CCT were not significantly different between the groups. The impact of obesity on anterior chamber parameters should be further investigated. PMID:26240505

The mechanism of transient myopia induced by sulfonamide therapy.

PubMed

Bovino, J A; Marcus, D F

1982-07-01

We performed acute and convalescent A-scan echographic ocular measurements documenting the anterior chamber depth, lens thickness, and axial length of a patient with acute transient sulfamethoxazole-induced myopia. Shallowing of the anterior chamber, independent of changes in the thickness of the lens, was the only anatomic variation found that could explain the myopia. Swelling of the ciliary body, with forward movement of the lens-iris diaphragm, could produce this transient anatomic change.

[Pigment dispersion syndrome and pigmentary glaucoma. Morphometric analysis of the anterior chamber segment with SL-OCT].

PubMed

Birner, B; Tourtas, T; Wessel, J M; Jünemann, A G; Mardin, C Y; Kruse, F E; Laemmer, R

2014-01-01

The purpose of this study was to analyze if anterior chamber parameters are risk factors for the development of pigment dispersion syndrome (PDS) and/or for the conversion to pigmentary glaucoma (PG). This study included a total of 63 eyes from 35 patients with PDS and PG and 65 eyes from 49 unaffected volunteers as the control group. The following parameters were measured by slit lamp optical coherence tomography (SL-OCT): anterior chamber volume (ACV) and depth (ACD), angle opening distance (AOD) and the trabecular iris space area (TISA) at 500 µm and 750 μm from the scleral spur. Comparisons between the following groups were performed: between the PDS/PG and the control group, between PDS and PG and between male and female patients. The results of ACV, ACD, AOD and TISA were significantly higher in PDS/PG patients when compared to the control group. There were no significant differences between PDS and PG. The gender-specific comparison also showed no significant differences. Significantly higher anterior chamber parameters are a possible risk factor for development of PDS; however, a higher risk of conversion to PG does not seem to correlate with increased anterior chamber parameters. The parameters of the anterior chamber are apparently not associated with the male predominance of PDS and PG.

Crystalline lens power and refractive error.

PubMed

Iribarren, Rafael; Morgan, Ian G; Nangia, Vinay; Jonas, Jost B

2012-02-01

To study the relationships between the refractive power of the crystalline lens, overall refractive error of the eye, and degree of nuclear cataract. All phakic participants of the population-based Central India Eye and Medical Study with an age of 50+ years were included. Calculation of the refractive lens power was based on distance noncycloplegic refractive error, corneal refractive power, anterior chamber depth, lens thickness, and axial length according to Bennett's formula. The study included 1885 subjects. Mean refractive lens power was 25.5 ± 3.0 D (range, 13.9-36.6). After adjustment for age and sex, the standardized correlation coefficients (β) of the association with the ocular refractive error were highest for crystalline lens power (β = -0.41; P < 0.001) and nuclear lens opacity grade (β = -0.42; P < 0.001), followed by axial length (β = -0.35; P < 0.001). They were lowest for corneal refractive power (β = -0.08; P = 0.001) and anterior chamber depth (β = -0.05; P = 0.04). In multivariate analysis, refractive error was significantly (P < 0.001) associated with shorter axial length (β = -1.26), lower refractive lens power (β = -0.95), lower corneal refractive power (β = -0.76), higher lens thickness (β = 0.30), deeper anterior chamber (β = 0.28), and less marked nuclear lens opacity (β = -0.05). Lens thickness was significantly lower in eyes with greater nuclear opacity. Variations in refractive error in adults aged 50+ years were mostly influenced by variations in axial length and in crystalline lens refractive power, followed by variations in corneal refractive power, and, to a minor degree, by variations in lens thickness and anterior chamber depth.

Optical and Biometric Characteristics of Anisomyopia in Human Adults

PubMed Central

Tian, Yibin; Tarrant, Janice; Wildsoet, Christine F.

2011-01-01

Purpose To investigate the role of higher order optical aberrations and thus retinal image degradation in the development of myopia, through the characterization of anisomyopia in human adults in terms of their optical and biometric characteristics. Methods The following data were collected from both eyes of fifteen young adult anisometropic myopes and sixteen isometropic myopes: subjective and objective refractive errors, corneal power and shape, monochromatic optical aberrations, anterior chamber depth, lens thickness, vitreous chamber depth, and best corrected visual acuity. Monochromatic aberrations were analyzed in terms of their higher order components, and further analyzed in terms of 31 optical quality metrics. Interocular differences for the two groups (anisomyopes vs. isomyopes) were compared and the relationship between measured ocular parameters and refractive errors also analyzed across all eyes. Results As expected, anisomyopes and isomyopes differed significantly in terms of interocular differences in vitreous chamber depth, axial length and refractive error. However, interocular differences in other optical properties showed no significant intergroup differences. Overall, higher myopia was associated with deeper anterior and vitreous chambers, higher astigmatism, more prolate corneas, and more positive spherical aberration. Other measured optical and biometric parameters were not significantly correlated with spherical refractive error, although some optical quality metrics and corneal astigmatism were significantly correlated with refractive astigmatism. Conclusions An optical cause for anisomyopia related to increased higher order aberrations is not supported by our data. Corneal shape changes and increased astigmatism in more myopic eyes may be a by-product of the increased anterior chamber growth in these eyes; likewise, the increased positive spherical aberration in more myopic eyes may be a product of myopic eye growth. PMID:21797915

Anterior Segment Morphology in Primary Angle Closure Glaucoma using Ultrasound Biomicroscopy

PubMed Central

Balakrishna, Nagalla

2017-01-01

Aim To evaluate the configuration of the anterior chamber angle quantitatively and study the morphological changes in the eye with ultrasound biomicroscopy (UBM) in primary angle closure glaucoma (PACG) patients after laser peripheral iridotomy (LPI). Materials and methods A total of 185 eyes of 185 PACG patients post-LPI and 126 eyes of 126 normal subjects were included in this prospective study. All subjects underwent complete ophthalmic evaluation, A-scan biometry, and UBM. The anterior segment and angle parameters were measured quantitatively and compared in both groups using Student’s t-test. Results The PACG patients had shorter axial length, shallower central anterior chamber depth anterior chamber depth (ACD), and anteriorly located lens when compared with normal subjects. Trabecular iris angle (TIA) was significantly narrow (5.73 ± 7.76°) in patients with PACG when compared with normal subjects (23.75 ± 9.38°). The angle opening distance at 500 pm from scleral spur (AOD 500), trabecular-ciliary process distance (TCPD), iris-ciliary process distance (ICPD), and iris-zonule distance (IZD) were significantly shorter in patients with PACG than in normal subjects (p < 0.0001). The iris lens angle (ILA), scleral-iris angle (SIA), and scleral-ciliary process angle (SCPA) were significantly narrower in patients with PACG than in normal subjects (p < 0.0001). The iris-lens contact distance (ILCD) was greater in PACG group than in normal (p = 0.001). Plateau iris was seen in 57/185 (30.8%) of the eyes. Anterior positioned ciliary processes were seen in 130/185 eyes (70.3%) of eyes. Conclusion In PACG patients, persistent apposition angle closure is common even after LPI, which could be due to anterior rotation of ciliary body and plateau iris and overcrowding of anterior segment due to shorter axial length and relative anterior lens position. How to cite this article: Mansoori T, Balakrishna N. Anterior Segment Morphology in Primary Angle Closure Glaucoma using Ultrasound Biomicroscopy. J Curr Glaucoma Pract 2017;11(3):86-91. PMID:29151682

The effects of methylphenidate on refraction and anterior segment parameters in children with attention deficit hyperactivity disorder.

PubMed

Larrañaga-Fragoso, Paula; Noval, Susana; Rivero, José C; Boto-de-los-Bueis, Ana

2015-08-01

Methylphenidate hydrochloride is used as first-line treatment for attention deficit hyperactivity disorder (ADHD). However, there is concern that this treatment may be associated with increased risk of angle closure glaucoma and disturbance of ocular refraction. The aim of this study was to investigate the effects of methylphenidate treatment on refraction, intraocular pressure, and the anterior chamber in children with ADHD. In this prospective pilot study, children diagnosed with ADHD were examined before the start of methylphenidate treatment and again 3 and 9 months after the start of treatment. Ocular examination before and after cycloplegia was performed at each visit, including Pentacam imaging of the anterior chamber. A total of 14 patients (mean age, 11 years) were recruited. The mean visual acuity, sphere, spherical equivalent refraction, intraocular pressure, and cup:disk ratio did not change significantly after the start of treatment. The anterior chamber depth after cycloplegia decreased significantly between baseline and 9 months, from 3.26 ± 0.22 mm to 3.24 ± 0.23 mm in the right eye (P = 0.037) and from 3.28 ± 0.22 mm to 3.25 ± 0.24 mm in the left eye (P = 0.001). Methylphenidate does not seem to affect refraction in most children with ADHD. After 9 months of treatment, however, there was a reduction in the anterior chamber depth, which has been described as a powerful predictor of angle closure glaucoma. Further investigation of the potential ocular side effects of methylphenidate treatment is warranted. Copyright © 2015 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Comparison of AL-Scan and IOLMaster 500 Partial Coherence Interferometry Optical Biometers.

PubMed

Hoffer, Kenneth J; Savini, Giacomo

2016-10-01

To investigate agreement between the ocular biometry measurements provided by a newer optical biometer, the AL-Scan (Nidek Co, Ltd., Gamagori, Japan) and those provided by the IOLMaster 500 (Carl Zeiss Meditec, Jena Germany), which are both based on partial coherence interferometry. Axial length, corneal power, and anterior chamber depth (corneal epithelium to lens) were measured in 86 eyes of 86 patients scheduled for cataract surgery using both biometers. All values were analyzed using a paired t test, the Pearson product moment correlation coefficient (r), and Bland-Altman plots. The mean axial length values of both instruments were exactly the same (23.46 ± 0.99 mm) for both) and showed excellent agreement and correlation. On the contrary, the AL-Scan measured a steeper mean corneal power by 0.08 diopters (D) at the 2.4-mm zone but by only 0.03 D at the 3.3-mm zone, only the former being statistically significant. The AL-Scan measured a deeper anterior chamber depth by 0.13 mm, which was statistically significant (P < .001). Agreement between the two units was good. However, the small but statistically significant difference in corneal power (at the IOLMaster-comparable 2.4-mm zone) and in the anterior chamber depth measurement make lens constant optimization necessary when calculating the intraocular lens power by means of theoretical formulas. [J Refract Surg. 2016;32(10):694-698.]. Copyright 2016, SLACK Incorporated.

[Are biometric parameters of anterior segment of the eyeball influenced by type 2 diabetes?].

PubMed

Dmuchowska, Diana A; Kraśnicki, Paweł; Mariak, Zofia

2012-01-01

To answer the question whether biometric parameters of anterior segment of the eyeball are influenced by type 2 diabetes, at the stage when the lens is still transparent, so before cataract development. Fifty subjects (28 women and 22 men), at the age of 63.3 +/- 11.3 years were enrolled in this prospective study. They were divided in 2 groups: patients with type 2 diabetes (24 subjects) and analogous age group in good general health - control group (26 subjects). None of the tested individuals presented lens opacities. The planned biometric measurements included: central corneal thickness, anterior chamber depth and axial lens thickness. The data were statistically analyzed. There was no difference between the groups of both proven and potential parameters that are associated with biometric measurements of the anterior segment of the eyeball, such as: gender, age, smoking and axial length of the eye. In diabetic patients, as opposed to the subjects in the control group, statistically significantly increased lens thickness (4.78 +/- 0.50 mm vs 4.43 +/- 0.50; p = 0.016), central corneal thickness (561.5 +/- 31.6 microm vs 542.2 +/- 35.2; p = 0.047), and the tendency for shallow anterior chamber (3.06 +/- 0.40 mm vs 3.22 +/- 0.38; p = 0.159), were observed. In patients with diabetes there was no association of the biometric parameters values with the duration of diabetes and presence of diabetic retinopathy. Type 2 diabetes contributes to increased axial corneal and lens thickness at the stage when the lens is transparent, albeit it does not significantly affect anterior chamber depth.

21 CFR 886.4275 - Intraocular fluid.

Code of Federal Regulations, 2010 CFR

2010-04-01

... performance of surgery, such as to maintain anterior chamber depth, preserve tissue integrity, protect tissue from surgical trauma, or function as a tamponade during retinal reattachment. (b) Classification. Class...

21 CFR 886.4275 - Intraocular fluid.

Code of Federal Regulations, 2011 CFR

2011-04-01

... performance of surgery, such as to maintain anterior chamber depth, preserve tissue integrity, protect tissue from surgical trauma, or function as a tamponade during retinal reattachment. (b) Classification. Class...

Effects of Birth Weight on Anterior Segment Measurements in Full-Term Children Without Low Birth Weight by Dual-Scheimpflug Analyzer.

PubMed

Yeter, Volkan; Aritürk, Nurşen; Bİrİncİ, Hakki; Süllü, Yüksel; Güngör, İncİ

2015-10-01

To evaluate the effects of birth weight on ocular anterior segment parameters in full-term children without low birth weight using the Galilei Dual-Scheimpflug Analyzer. Retrospective cohort study. The right eyes from 110 healthy children, 3-6 years of age, were scanned with the Galilei Dual-Scheimpflug Analyzer. A total of 78 eyes were measured in full-term children with birth weight of >2500 g. Central, paracentral, pericentral, and the thinnest corneal thicknesses; anterior and posterior keratometry (average, steep, flat); axial curvatures; asphericity of cornea; anterior chamber depth and volume; and iridocorneal angle values were measured. Axial length, lens thickness, and vitreous length were obtained by ultrasound biometry. The mean age of children was 55.86 ± 12.52 (mean ± SD) months. Mean birth weight and gestational age were 3426.3 ± 545 g and 39.4 ± 1.2 weeks, respectively. Although lens thickness, vitreous length, axial length, and anterior chamber volume were moderately correlated with birth weight (P < .05), there was no relationship between birth weight and anterior chamber depth. With the exception of pericentral corneal thickness, all regions of corneal thicknesses were correlated with birth weight (P < .05). Birth weight was negatively correlated with anterior curvature (P < .05) and had no relationship to posterior curvature. While central and paracentral axial curvatures correlated with birth weight (P < .05), pericentral axial curvature did not. Preschoolers who were born heavier had thicker cornea and lens, longer axial length, and flatter corneal curve. The thicknesses and axial curves of central cornea within 7 mm may be particularly associated with birth weight. Copyright © 2015 Elsevier Inc. All rights reserved.

High frequency ultrasound imaging in pupillary block glaucoma.

PubMed Central

Aslanides, I M; Libre, P E; Silverman, R H; Reinstein, D Z; Lazzaro, D R; Rondeau, M J; Harmon, G K; Coleman, D J

1995-01-01

BACKGROUND--The diagnosis of pupillary block glaucoma requires sufficient clarity of the ocular media. This is particularly important for assessment of both the presence and patency of an iridotomy, and the determination of central anterior chamber depth. METHODS--High frequency ultrasonography was used in three patients with suspected pupillary block to determine iris configuration, posterior chamber volume, and ciliary body conformation. RESULTS--All patients demonstrated high frequency ultrasonographic findings consistent with pupillary block: iris bombé, a formed posterior chamber, and a lack of anterior rotation of the ciliary processes. CONCLUSION--High frequency ultrasound imaging appears to be a valuable adjunct in making or corroborating the diagnosis of pupillary block glaucoma. Images PMID:8534666

Manipulation of intraocular pressure for studying the effects on accommodation.

PubMed

He, Lin; Wendt, Mark; Glasser, Adrian

2012-09-01

A reliable experimental system in which IOP can be manipulated or a rapid IOP change can be induced while simultaneously and continuously measuring IOP and the ocular accommodative changes would be useful for understanding the physiological effect of intraocular pressure (IOP) on the accommodative mechanism. In this study, an IOP perfusion and recording system was developed and tested using 13 enucleated pig eyes. The vitreous chamber of the pig eyes was cannulated with a needle connected to two fluid reservoirs at different heights. One reservoir was set to achieve one of three baseline pressures of 5.5 mmHg, 13.0 mmHg and 20.5 mmHg. The other reservoir was moved to achieve pressures of 1.5 mmHg, 3.0 mmHg, 4.5 mmHg and 6.0 mmHg higher than the baseline pressure. The height differential between the reservoirs determined the amplitude of IOP changes. Rapid IOP changes were induced by switching the reservoirs with a solenoid pinch-valve. Two needles, one each attached to a pressure transducer were inserted into the anterior chamber and vitreous chamber respectively. Custom developed software was used to measure the anterior chamber pressure and vitreous chamber pressure at 80 Hz. A high-resolution continuous A-scan ultrasound biometer (CUB) was used to dynamically measure changes in ocular biometry including anterior chamber depth (ACD), lens thickness (LT) and vitreous chamber depth (VCD) while the vitreous chamber pressure was manipulated. The changes in ACD, LT and VCD were analyzed as a function of the pressure change. Perfusion-induced axial biometric changes were quantified by the slopes of linear regression relationships. Both anterior chamber pressure and vitreous chamber pressure changed relatively systematically with the induced vitreous chamber pressure changes (anterior chamber: y = 0.863x + 0.030, r(2) = 0.983; vitreous chamber: y = 0.883x + 0.009, r(2) = 0.981). At perfusion pressures of 5.5, 13.0 and 20.5 mmHg, the slopes for ACD were -5.72, -2.75 and -2.36 μm/mmHg, for LT were -3.31, -1.59 and -1.03 μm/mmHg and for VCD were 19.05, 8.63 and 5.18 μm/mmHg. The system was able to manipulate and monitor IOP while axial biometry changes were recorded. This system will allow the relationship between IOP and accommodation to be studied in non-human primate eyes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Glaucoma anterior chamber morphometry based on optical Scheimpflug images.

PubMed

Alonso, Ruiz Simonato; Ambrósio Junior, Renato; Paranhos Junior, Augusto; Sakata, Lisandro Massanori; Ventura, Marcelo Palis

2010-01-01

To compare the performance of gonioscopy and noncontact morphometry with anterior chamber tomography (High Resolution Pentacam - HR) using optical Scheimpflug images in the evaluation of the anterior chamber angle (ACA). Transversal study. 112 eyes from 74 subjects evaluated at the Glaucoma Department, Fluminense Federal University, underwent gonioscopy and Pentacam HR. Using gonioscopy, the ACA was graded using the Shaffer Classification (SC) by a single experienced examiner masked to the Pentacam HR findings. Narrow angle was determined in eyes in which the posterior trabecular meshwork could not be seen in two or more quadrants on non-indentation gonioscopy (SC Grade 2 or less). Pentacam HR images of the nasal and temporal quadrants were evaluated by custom software to automatically obtain anterior chamber measurements, such as: anterior chamber angle (ACA), anterior chamber volume (ACV) and anterior chamber depth (ACD). Based on gonioscopy results, 74 (60.07%) eyes of patients classified as open-angle (SC 3 and 4) and 38 (33.93%) eyes of patients classified as narrow-angle (SC 1 and 2). Noncontact morphometry with Scheimpflug images revealed a mean ACA of 39.20 ± 5.31 degrees for open-angle and 21.18 ± 7.98 degrees for narrow-angle. The open-angle group showed significant greater ACV and ACD values when compared to narrow-angle group (ACV of 193 ± 36 mm³ vs. 90 ± 25 mm³, respectively, p<0.001; and ACD of 3,09 ± 0,42 mm vs. 1,55 ± 0,64 mm, respectively, p<0.0001.). In screening eyes with open-angle and narrow-angle with the Pentacam ACA of 20º (SC Grade 2) using the ROC curves, the analysis showed 52.6% of sensitivity and 100% of specificity. The Pentacam showed ability in detecting eyes at risk for angle closure analyzing ACV and ACD.

Objective evaluation of the changes in the crystalline lens during accommodation in young and presbyopic populations using Pentacam HR system.

PubMed

Ni, Yao; Liu, Xia-Lin; Wu, Ming-Xing; Lin, Ying; Sun, Yu-Ying; He, Chang; Liu, Yi-Zhi

2011-01-01

To quantify the changes in the lens profile with accommodation in different age groups. The Pentacam HR system was used to obtain the images of the anterior eye segment from 23 young and 15 presbyopic emmetropic subjects in unaccommodated (with an accommodation stimulus of 0.0D) and accommodated (with an accommodation stimulus of 5.0D for the young group and 1.0D for the presbyopic group) states. The phakic crystalline lens shape, including curvature of crystalline lens and central lens thickness (CLT), and the measurements of anterior segment length (ASL), central anterior chamber depth (CACD) were investigated. The anterior chamber volume (ACV) was also measured. The reduction of CACD and ACV were significant in both groups after accommodation stimulus. From the profile of anterior eye segment, a significant decrease in anterior crystalline lens radii of curvature (-2.52mm) and a mean increase in CLT (0.222mm) and ASL (0.108mm) were found in the young group with an accommodation stimulus of 5.0D. However, no statistically significant changes of CLT, ASL, or crystalline lens radii of curvature were found in the presbyopic group. Our data showed that the shallowing of anterior chamber during accommodation was caused by the forward bulging of the anterior lens surface, rather than by anterior shifting of lens position in either young or presbyopic subjects.

Assessment of intraocular measurements in neonatal foals and association with gender, laterality, and body weight: a clinical study.

PubMed

Valentini, Simona; Castagnetti, Carolina; Musella, Vincenzo; Spinella, Giuseppe

2014-01-01

Objective of this study was to describe intraocular measurements in newly born foals (1-7 days of age) and assess the association between globe measurements and gender, laterality, and body weight. B-scan ultrasonographic biometry was performed on both eyes of 22 healthy foals (44 eyes) ages 1-7 days using a 10-MHz transducer. Intraocular measurements (anterior chamber depth, central lens thickness, vitreous chamber depth, axial globe length, longitudinal globe length, lens poles distance) were carried out using the ultrasound internal calipers. The influence of gender (male or female), laterality (right or left eye), and body weight ("light" <48 kg; "heavy" ≥48 kg) on ocular measurements was analysed by the Student t test. Values of P<0.05 were accepted as significant for all analyses. Mean anterior chamber depth was 2.2±0.5 mm (Standard Deviation); central lens thickness was 9.9±0.8 mm; vitreous chamber depth was 15.5±1.1 mm; axial globe length was 27.6±1.6 mm; longitudinal globe length was 35.8±1.2 mm, and lens poles distance was 16.4±1.0 mm. Intraocular measurements were not influenced by gender, laterality nor body weight. This study provides reference values for intraocular measurements in neonatal foals and may be useful in the diagnosis and treatment of congenital and acquired pathologies involving the globe.

Assessment of Intraocular Measurements in Neonatal Foals and Association with Gender, Laterality, and Body Weight: A Clinical Study

PubMed Central

Valentini, Simona; Castagnetti, Carolina; Musella, Vincenzo; Spinella, Giuseppe

2014-01-01

Objective of this study was to describe intraocular measurements in newly born foals (1–7 days of age) and assess the association between globe measurements and gender, laterality, and body weight. B-scan ultrasonographic biometry was performed on both eyes of 22 healthy foals (44 eyes) ages 1–7 days using a 10-MHz transducer. Intraocular measurements (anterior chamber depth, central lens thickness, vitreous chamber depth, axial globe length, longitudinal globe length, lens poles distance) were carried out using the ultrasound internal calipers. The influence of gender (male or female), laterality (right or left eye), and body weight (“light” <48 kg; “heavy” ≥48 kg) on ocular measurements was analysed by the Student t test. Values of P<0.05 were accepted as significant for all analyses. Mean anterior chamber depth was 2.2±0.5 mm (Standard Deviation); central lens thickness was 9.9±0.8 mm; vitreous chamber depth was 15.5±1.1 mm; axial globe length was 27.6±1.6 mm; longitudinal globe length was 35.8±1.2 mm, and lens poles distance was 16.4±1.0 mm. Intraocular measurements were not influenced by gender, laterality nor body weight. This study provides reference values for intraocular measurements in neonatal foals and may be useful in the diagnosis and treatment of congenital and acquired pathologies involving the globe. PMID:25296286

Effect of primary iris and ciliary body cyst on anterior chamber angle in patients with shallow anterior chamber*

PubMed Central

Wang, Bing-hong; Yao, Yu-feng

2012-01-01

Objective: To evaluate the prevalence of primary iris and/or ciliary body cysts in eyes with shallow anterior chamber and their effect on the narrowing of the anterior chamber angle. Methods: Among the general physical check-up population, subjects with shallow anterior chambers, as judged by van Herick technique, were recruited for further investigation. Ultrasound biomicroscope (UBM) was used to detect and measure the cysts located in the iris and/or ciliary body, the anterior chamber depth (ACD), the angle opening distance at 500 μm (AOD500), and the trabecular-iris angle (TIA). A-scan ultrasonography was used to measure the ocular biometry, including lens thickness, axial length, lens/axial length factor (LAF), and relative lens position (RLP). The effect of the cyst on narrowing the corresponding anterior chamber angle and the entire angle was evaluated by the UBM images, ocular biometry, and gonioscopic grading. The eye with unilateral cyst was compared with the eye without the cyst for further analysis. Results: Among the 727 subjects with shallow anterior chamber, primary iris and ciliary body cysts were detected in 250 (34.4%) patients; among them 96 (38.4%) patients showed unilateral single cyst, 21 (8.4%) patients had unilateral double cysts, and 42 (16.8%) patients manifested unilateral multiple and multi-quadrants cysts. Plateau iris configuration was found in 140 of 361 (38.8%) eyes with cysts. The mean size of total cysts was (0.6547±0.2319) mm. In evaluation of the effect of the cyst size and location on narrowing the corresponding angle to their position, the proportion of the cysts causing corresponding angle narrowing or closure among the cysts larger than 0.8 mm (113/121, 93.4%) was found to be significantly higher than that of the cysts smaller than 0.8 mm (373/801, 46.6%), and a significant higher proportion was also found in the cysts located at iridociliary sulcus (354/437, 81.0%) than in that at the pars plicata (131/484, 27.1%). In evaluating the effect of the cyst on the entire anterior chamber angle, the eyes with multiple and multi-quadrants cysts manifested significant narrowing of the entire anterior chamber angle as compared with the eyes without cysts, based on the data analysis in comparison of TIA, AOD500, and gonioscopic grading evaluation. The unilateral single or double cysts in the eyes had no significant effect on narrowing of anterior chamber angle as compared with eyes without cysts. The iris and/or ciliary body cysts did not seem to affect the axial length, ACD, lens thickness, RLP, LAF. Conclusions: The prevalence of primary iris and ciliary body cyst was 34.4% in the subjects with shallow anterior chamber. The cysts larger than 0.8 mm, locating at iridociliary sulcus, or multiple and extensive cysts were inclined to cause the angle narrowing or closure. PMID:22949363

Diurnal Alterations of Refraction, Anterior Segment Biometrics, and Intraocular Pressure in Long-Time Dehydration due to Religious Fasting.

PubMed

Baser, Gonen; Cengiz, Hakan; Uyar, Murat; Seker Un, Emine

2016-01-01

To investigate the effects of dehydration due to fasting on diurnal changes of intraocular pressure, anterior segment biometrics, and refraction. The intraocular pressures, anterior segment biometrics (axial length: AL; Central corneal thickness: CCT; Lens thickness: LT; Anterior chamber depth: ACD), and refractive measurements of 30 eyes of 15 fasting healthy male volunteers were recorded at 8:00 in the morning and 17:00 in the evening in the Ramadan of 2013 and two months later. The results were compared and the statistical analyses were performed using the Rstudio software version 0.98.501. The variables were investigated using visual (histograms, probability plots) and analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk test) to determine whether or not they were normally distributed. The refractive values remained stable in the fasting as well as in the control period (p = 0.384). The axial length measured slightly shorter in the fasting period (p = 0.001). The corneal thickness presented a diurnal variation, in which the cornea measured thinner in the evening. The difference between the fasting and control period was not statistically significant (p = 0.359). The major differences were observed in the anterior chamber depth and IOP. The ACD was shallower in the evening during the fasting period, where it was deeper in the control period. The diurnal IOP difference was greater in the fasting period than the control period. Both were statistically significant (p = 0.001). The LT remained unchanged in both periods. The major difference was shown in the anterior chamber shallowing in the evening hours and IOP. Our study contributes the hypothesis that the posterior segment of the eye is more responsible for the axial length alterations and normovolemia has a more dominant influence on diurnal IOP changes.

Non-invasive measurements of the dynamic changes in the ciliary muscle, crystalline lens morphology, and anterior chamber during accommodation with a high-resolution OCT.

PubMed

Esteve-Taboada, José J; Domínguez-Vicent, Alberto; Monsálvez-Romín, Daniel; Del Águila-Carrasco, Antonio J; Montés-Micó, Robert

2017-07-01

The purpose of the study was to assess non-invasively the changes in the anterior chamber eye, crystalline lens morphology, and ciliary muscle during accommodation by means of an anterior chamber optical coherence tomographer (OCT), and correlate them with vergence. Twenty-five eyes of twenty-five healthy subjects, whose mean age was 29.9±7.1 years, were included and measured with an anterior chamber OCT. The central corneal thickness (CCT), anterior chamber depth (ACD), anterior crystalline lens radius of curvature (ALRC), crystalline lens thickness (CLT), and ciliary muscle area (CMA) were measured for each participant at 0, -1, -2, and -3 D of target vergence. A linear model was used to assess the correlation of each eye parameter with the vergence demand. The mean CCT showed no change for all the accommodative stimuli. The mean ACD and ALRC decreased with the vergence, about 4.5 and 30 % at -3 D, respectively. On the contrary, the CLT and CMA showed an opposite tendency, where the mean CLT was increased by 4.0 % and the mean CMA was done by 26% at -3 D. Statistical significant differences (p < 0.001) were obtained among all vergences for each eye metric, except for the CCT (p = 0.76). The ACD and ALRC decreased about 2 and 10 % per dioptre of accommodation, respectively; whereas the CLT and CMA increased about 2 and 9 %, respectively. These results add knowledge regarding the understanding of accommodation and give new perspectives for biomechanics and biometry.

Biometric analysis of pigment dispersion syndrome using anterior segment optical coherence tomography.

PubMed

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

2011-08-01

To compare anterior chamber volume (ACV), iris volume, and iridolenticular contact (ILC) area before and after laser peripheral iridotomy (LPI) in eyes with pigment dispersion syndrome (PDS) using anterior segment optical coherence tomography (AS OCT) and image processing software. Cross-sectional study. Eighteen eyes of 18 patients with PDS; 30 eyes of 30 controls matched for age, gender, and refraction. Anterior segment OCT imaging was performed in all eyes before LPI and 1, 4, and 12 weeks after LPI. At each visit, 12 cross-sectional images of the AS were taken: 4 in bright conditions with accommodation (accommodation), 4 in bright conditions without accommodation (physiological miosis), and 4 under dark conditions (physiologic mydriasis). Biometric parameters were estimated using AS OCT radial sections and customized image-processing software. Anterior chamber volume, iris volume-to-length ratio, ILC area, AS OCT anterior chamber depth, and A-scan ultrasonography axial length. Before LPI, PDS eyes had a significantly greater ACV and ILC area than control eyes (P<0.01) and a significantly smaller iris volume-to-length ratio than the controls (P<0.05). After LPI, ACV and ILC area decreased significantly in PDS eyes, but iris volume-to-length ratio increased significantly (P<0.02) and was not significantly different from that of controls. These biometric changes were stable over time. Iris volume-to-length ratio decreased significantly from accommodation to mydriasis and from miosis to mydriasis, both in PDS and control eyes (P<0.01). In PDS eyes, ILC area decreased significantly from accommodation to mydriasis, both before and after LPI (P<0.01). On multivariate analysis, greater anterior chamber (AC) volume (P<0.02) and larger AC depth (P<0.05) before LPI were significant predictors of a larger ILC area. Pigment dispersion syndrome eyes do not have an iris that is abnormally large, relative to the AS size, but have a weakly resistant iris that is stretched and pushed against the lens when there is a pressure difference across the iris. The author(s) have no proprietary or commercial interest in any materials discussed in this article. Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Anterior segment parameters of rabbits with rotating Scheimpflug camera.

PubMed

Yüksel, Harun; Türkcü, Fatih M; Ari, Şeyhmus; Çinar, Yasin; Cingü, Abdullah K; Şahin, Muhammed; Şahin, Alparslan; Özkurt, Zeynep; Çaça, İhsan

2015-05-01

Rabbit is one of the most commonly used experimental animals for corneal studies due to similarity of size to human cornea and ease of manipulation. In this study, we assessed anterior segment parameters of the healthy rabbit eyes with Pentacam HR (Oculus, Wetzlar, Germany). Six-month-old, approximately 2.5-3 kg weighted, 30 female New Zealand rabbits were used in the study. Right eye of the each rabbit was imaged with Pentacam HR under intramuscular ketamine hydrochloride (Ketalar; Eczacibasi, Turkey) anesthesia (50 mg/kg). After the imaging, the rabbits with blinking errors, which results in low-quality images, were excluded from the study. Keratometric readings, central corneal thickness (CCT), anterior chamber depth (ACD), and anterior and posterior elevation values, and lens density were noted. In this study, the flattest and the steepest keratometric values were found as 43.34 ± 1.86, 42.7 ± 2.0, and 43.9 ± 1.9 diopters, respectively. The mean CCT and ACD of rabbits were found as 388 ± 39 μm and 2.08 ± 0.16 mm, respectively. Mean of the anterior and posterior elevation at thinnest point was found as 1.29 ± 4.28 and 3.91 ± 6.17 μm, respectively. Keratometric readings and anterior and posterior elevation values of rabbits were similar to human; however, corneal thickness and anterior chamber depth (ACD) values were lower than humans. © 2014 American College of Veterinary Ophthalmologists.

Comparison of slitlamp optical coherence tomography and scanning peripheral anterior chamber depth analyzer to evaluate angle closure in Asian eyes.

PubMed

Wong, Hon-Tym; Chua, Jocelyn L L; Sakata, Lisandro M; Wong, Melissa H Y; Aung, Han T; Aung, Tin

2009-05-01

To evaluate the effectiveness of slitlamp optical coherence tomography (SL-OCT) and Scanning Peripheral Anterior Chamber depth analyzer (SPAC) in detecting angle closure, using gonioscopy as the reference standard. A total of 153 subjects underwent gonioscopy, SL-OCT, and SPAC. The anterior chamber angle (ACA) was classified as closed on gonioscopy if the posterior trabecular meshwork could not be seen; with SL-OCT, closure was determined by contact between the iris and angle wall anterior to the scleral spur; and with SPAC by a numerical grade of 5 or fewer and/or a categorical grade of suspect or potential. A closed ACA was identified in 51 eyes with gonioscopy, 86 eyes with SL-OCT, and 61 eyes with SPAC (gonioscopy vs SL-OCT, P < .001; gonioscopy vs SPAC, P = .10; SL-OCT vs SPAC, P < .001; McNemar test). Of the 51 eyes with a closed ACA on gonioscopy, SL-OCT detected a closed ACA in 43, whereas SPAC identified 41 (P = .79). An open angle in all 4 quadrants was observed in 102 eyes with gonioscopy, but SL-OCT and SPAC identified 43 and 20 of these eyes, respectively, as having angle closure. The overall sensitivity and specificity for SL-OCT were 84% and 58% vs 80% and 80% for SPAC. Using gonioscopy as the reference, SL-OCT and SPAC showed good sensitivity for detecting eyes at risk of angle closure.

Effect of Nocturnal Intermittent Peritoneal Dialysis on Intraocular Pressure and Anterior Segment Optical Coherence Tomography Parameters.

PubMed

Chong, Ka Lung; Samsudin, Amir; Keng, Tee Chau; Kamalden, Tengku Ain; Ramli, Norlina

2017-02-01

To evaluate the effect of nocturnal intermittent peritoneal dialysis (NIPD) on intraocular pressure (IOP) and anterior segment optical coherence tomography (ASOCT) parameters. Systemic changes associated with NIPD were also analyzed. Observational study. Nonglaucomatous patients on NIPD underwent systemic and ocular assessment including mean arterial pressure (MAP), body weight, serum osmolarity, visual acuity, IOP measurement, and ASOCT within 2 hours both before and after NIPD. The Zhongshan Angle Assessment Program (ZAAP) was used to measure ASOCT parameters including anterior chamber depth, anterior chamber width, anterior chamber area, anterior chamber volume, lens vault, angle opening distance, trabecular-iris space area, and angle recess area. T tests and Pearson correlation tests were performed with P<0.05 considered statistically significant. A total of 46 eyes from 46 patients were included in the analysis. There were statistically significant reductions in IOP (-1.8±0.6 mm Hg, P=0.003), MAP (-11.9±3.1 mm Hg, P<0.001), body weight (-0.7±2.8 kg, P<0.001), and serum osmolarity (-3.4±2.0 mOsm/L, P=0.002) after NIPD. All the ASOCT parameters did not have any statistically significant changes after NIPD. There were no statistically significant correlations between the changes in IOP, MAP, body weight, and serum osmolarity (all P>0.05). NIPD results in reductions in IOP, MAP, body weight, and serum osmolarity in nonglaucomatous patients.

The Effect of Age, Accommodation and Refractive Error on the Adult Human Eye

PubMed Central

Richdale, Kathryn; Bullimore, Mark A.; Sinnott, Loraine T.; Zadnik, Karla

2015-01-01

Purpose To quantify changes in ocular dimensions associated with age, refractive error, and accommodative response, in vivo, in 30- to 50-year-old human subjects. Methods The right eyes of 91 adults were examined using ultrasonography, phakometry, keratometry, pachymetry, interferometry, anterior segment optical coherence tomography, and high resolution magnetic resonance imaging. Accommodation was measured subjectively with a push-up test and objectively using open-field autorefraction. Regression analyses were used to assess differences in ocular parameters with age, refractive error and accommodation. Results With age, crystalline lens thickness increased (0.03 mm/yr), anterior lens curvature steepened (0.11 mm/yr), anterior chamber depth decreased (0.02 mm/y) and lens equivalent refractive index decreased (0.001 /y) (all p < 0.01). With increasing myopia, there were significant increases in axial length (0.37 mm/D), vitreous chamber depth (0.34 mm/D), vitreous chamber height (0.09 mm/D) and ciliary muscle ring diameter (0.10 mm/D) (all p < 0.05). Increasing myopia was also associated with steepening of both the cornea (0.16 mm/D) and anterior lens surface (0.011 mm/D) (both p < 0.04). With accommodation, the ciliary muscle ring diameter decreased (0.08 mm/D), and the muscle thinned posteriorly (0.008 mm/D), allowing the lens to shorten equatorially (0.07 mm/D) and thicken axially (0.06 mm/D) (all p < 0.03). Conclusions Refractive error is significantly correlated with not only the axial dimensions, but the anterior equatorial dimension of the adult eye. Further testing and development of accommodating intraocular lenses should account for differences in patients’ preoperative refractive error. PMID:26703933

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.

Characterisation of the porcine eyeball as an in-vitro model for dry eye.

PubMed

Menduni, Francesco; Davies, Leon N; Madrid-Costa, D; Fratini, Antonio; Wolffsohn, James S

2018-02-01

To characterise the anatomical parameters of the porcine eye for potentially using it as a laboratory model of dry eye. Anterior chamber depth and angle, corneal curvature, shortest and longest diameter, endothelial cell density, and pachymetry were measured in sixty freshly enucleated porcine eyeballs. Corneal steepest meridian was 7.85±0.32mm, corneal flattest meridian was 8.28±0.32mm, shortest corneal diameter was 12.69±0.58mm, longest corneal diameter was 14.88±0.66mm and central corneal ultrasonic pachymetry was 1009±1μm. Anterior chamber angle was 28.83±4.16°, anterior chamber depth was 1.77±0.27mm, and central corneal thickness measured using OCT was 1248±144μm. Corneal endothelial cell density was 3250±172 cells/mm 2 . Combining different clinical techniques produced a pool of reproducible data on the porcine eye anatomy, which can be used by researchers to assess the viability of using the porcine eye as an in-vitro/ex-vivo model for dry eye. Due to the similar morphology with the human eye, porcine eyeballs may represent a useful and cost effective model to individually study important key factors in the development of dry eye, such as environmental and mechanical stresses. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Baerveldt drainage tube motility in the anterior chamber.

PubMed

Tan, Annelie N; De Witte, Pauline M; Webers, Carroll A B; Berendschot, Tos T J M; De Brabander, John; Schouten, Johannes S A G; Beckers, Henny J M

2014-01-01

To investigate the stability in position of the Baerveldt glaucoma drainage tube over time and to study movement of the drainage tube in the anterior chamber (AC) under varying light conditions. This prospective study included 70 eyes with implantation of a Baerveldt glaucoma drainage tube in the anterior chamber. Anterior segment optical coherence tomography (AS-OCT) images were made preoperatively to quantify AC depth. AS-OCT images were made twice under photopic and twice under scotopic conditions, in the angle parallel to the Baerveldt tube to quantify drainage tube position, at 3, 6, 12, and 24 months postoperatively. Tube-corneal (T-C) and tube-iris (T-I) distances were measured. Additionally, the central AC depth and the peripheral angle opening (AOD 500) were determined. Two subgroups were distinguished according to tube position: free in the AC (group 1, n = 48) and transiridal (group 2, n = 22). After 24 months of follow-up, the drainage tube was found to move statistically significantly closer (0.12 mm) to the corneal endothelium in group 1 (p<0.01). There was no statistically significant difference in T-C distance over time in group 2. The T-C distance did not differ under photopic versus scotopic circumstances (p = 0.32). In both groups, the T-I distance was larger under scotopic conditions, a result of pupil dilation. The Baerveldt glaucoma drainage tube remained in a stable position when a transiridal implantation was performed, whereas the tube moved closer to the endothelium when placed free into the AC. Transiridal implantation of the Baerveldt tube seems a safe alternative for tube implantation with respect to tube motility.

Imaging late capsular block syndrome: ultrasound biomicroscopy versus Scheimpflug camera.

PubMed

Kucukevcilioglu, Murat; Hurmeric, Volkan; Erdurman, Fazıl Cuneyt; Ceylan, Osman Melih

2011-11-01

We describe 2 patients with late capsular block syndrome whose anterior chamber morphology was evaluated with ultrasound biomicroscopy and Scheimpflug imaging before and after neodymium:YAG laser capsulotomy. Pretreatment ultrasound biomicroscopy examination showed significant capsular bag distension in both patients. Scheimpflug imaging failed to capture the posterior capsule displaced far behind the intraocular lens. Automatic anterior chamber depth measurements were incorrect with Scheimpflug imaging in 1 patient. Ultrasound biomicroscopy seems to be superior to Scheimpflug imaging in eyes with extremely distended capsular bags. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Correlation of corneal thickness, endothelial cell density and anterior chamber depth with ocular surface temperature in normal subjects.

PubMed

Pattmöller, Johanna; Wang, Jiong; Zemova, Elena; Seitz, Berthold; Eppig, Timo; Langenbucher, Achim; Szentmáry, Nóra

2015-09-01

To analyze corneal surface temperature profile in a young and healthy study population and to determine the impact of corneal thickness (CT), anterior chamber depth (ACD), and endothelial cell density (ECD) on surface temperature. In this prospective, single-center study 61 healthy right eyes of 61 subjects without tear film pathologies (mean age 24.9 ± 6.7 years) were recruited. Ocular surface temperature (OST) was measured with the Ocular Surface Thermographer TG-1000. From Pentacam HR CT and ACD, and from specular microscopy ECD and central corneal thickness (CCT) were acquired. From the raw measurement data (OST, CT and ACD) we extracted a) local OST the corneal center and 3mm away from the center at the 3, 6, and 9 o'clock positions, and b) Zernike parameters Z1, Z2 and Z3 to evaluate the general temperature profile within a 6mm circular area around the center. Overall, there was no correlation between OST and CT, ACD or ECD. Local OST did not correlate with CT at any measurement position. On average local OST was highest at measurement positions where CT was lowest, but without reaching statistical significance. Baseline OST was highest at thin corneal regions and temperature decay over time was smallest in those regions. Z1, Z2 and Z3 correlated well with CT. In healthy subjects corneal thickness, endothelial cell density and anterior chamber depth have no effect on corneal surface temperature. The general temperature profile seems to be influenced by the corneal thickness profile effecting a higher temperature and lower decay at thinner corneal regions. Copyright © 2014. Published by Elsevier GmbH.

High-hyperopia database, part I: clinical characterisation including morphometric (biometric) differentiation of posterior microphthalmos from nanophthalmos

PubMed Central

Relhan, N; Jalali, S; Pehre, N; Rao, H L; Manusani, U; Bodduluri, L

2016-01-01

Purpose To characterise and differentiate posterior microphthalmos (PM) and nanophthalmos (NO) using morphometric parameters. Patients and methods Consecutive case database of patients with hyperopia >+7.00 D sphere was analysed retrospectively for clinical and biometric characterisation. Thirty-eight consecutive high-hyperopic subjects (75 eyes) with axial lengths <20.5 mm underwent uniform comprehensive ocular evaluation. Twenty-five subjects were diagnosed as PM and 13 as NO based on the horizontal corneal diameter. Parameters analysed included visual acuity, refraction, horizontal corneal diameter, anterior chamber depth, lens thickness, axial length, fundus changes, and associated ocular pathology. Primary outcome measures: ocular biometry difference between PM and NO. Secondary outcome measures: differences in associated ocular pathologies between PM and NO. Results Hyperopia ranged from +7 to +17 D and was similar in the two groups. Lens thickness was statistically more in NO than in PM group (4.53±0.75 mm vs 3.82±0.48 mm, P <0.001), whereas anterior chamber depth was more in the PM than in NO group (3.26±0.36 mm, vs 2.59±0.37 mm, P<0.001). NO had higher association with angle-closure glaucoma (66.7% vs 0%) and pigmentary retinopathy (38.5 vs 8.0%) but lesser association with macular folds (0% vs 24%) as compared with PM. NO was associated with poorer visual acuity. Conclusion PM and NO have significant differences in lens thickness, anterior chamber depth, prevalence of glaucoma, pigmentary retinopathy, macular pathology, and visual acuity while being similar in hyperopic refraction. PMID:26493039

Cataract, phacoemulsification and intraocular pressure: Is the anterior segment anatomy the missing piece of the puzzle?

PubMed

Masis Solano, Marisse; Lin, Shan C

2018-01-29

Cataract extraction is a safe and effective surgery that has a lowering effect on the intraocular pressure. The specific mechanisms for this effect are still unclear. A direct inflammatory effect on the trabecular meshwork, alteration of the blood aqueous barrier, changes in the ciliary body and mechanical changes of the anterior segment anatomy are the key to understand cataract surgery and it's effects on aqueous humor dynamics. Additionally, with the advent of AS OCT, changes in the anterior segment of the eye have been studied and several parameters (such as lens vault, angle opening distance and anterior chamber depth) have been identified as predictors of intraocular pressure change. In eyes with narrow angles there is a greater drop in intraocular pressure after cataract surgery and it is correlated with parameters related to anterior chamber space. It is safe to affirm that cataract surgery is an important part of the modern glaucoma treatment and evidence should be analyzed as part of a bigger picture in order to more accurately understand its clinical relevance. Copyright © 2018. Published by Elsevier Ltd.

Precise measurement of scleral radius using anterior eye profilometry.

PubMed

Jesus, Danilo A; Kedzia, Renata; Iskander, D Robert

2017-02-01

To develop a new and precise methodology to measure the scleral radius based on anterior eye surface. Eye Surface Profiler (ESP, Eaglet-Eye, Netherlands) was used to acquire the anterior eye surface of 23 emmetropic subjects aged 28.1±6.6years (mean±standard deviation) ranging from 20 to 45. Scleral radius was obtained based on the approximation of the topographical scleral data to a sphere using least squares fitting and considering the axial length as a reference point. To better understand the role of scleral radius in ocular biometry, measurements of corneal radius, central corneal thickness, anterior chamber depth and white-to-white corneal diameter were acquired with IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany). The estimated scleral radius (11.2±0.3mm) was shown to be highly precise with a coefficient of variation of 0.4%. A statistically significant correlation between axial length and scleral radius (R 2 =0.957, p<0.001) was observed. Moreover, corneal radius (R 2 =0.420, p<0.001), anterior chamber depth (R 2 =0.141, p=0.039) and white-to-white corneal diameter (R 2 =0.146, p=0.036) have also shown statistically significant correlations with the scleral radius. Lastly, no correlation was observed comparing scleral radius to the central corneal thickness (R 2 =0.047, p=0.161). Three-dimensional topography of anterior eye acquired with Eye Surface Profiler together with a given estimate of the axial length, can be used to calculate the scleral radius with high precision. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Gonioscopy and ultrasound biomicroscopy in the detection of angle closure in patients with shallow anterior chamber.

PubMed

Cui, Shan-shan; Zou, Yan-hong; Li, Qian; Li, Li-na; Zhang, Ning; Liu, Xi-pu

2014-12-01

To assess the agreement between gonioscopy and ultrasound biomicroscopy (UBM) in detecting angle closure in Chinese patients with shallow anterior chamber. An observational comparative study of the two different examination methods was conducted. Patients with normal intraocular pressure and temporal peripheral anterior chamber depth less than a quarter of corneal thickness based on slit lamp examination were included in this study from December 2007 to May 2009 in the outpatient clinic of First Hospital of Tsinghua University. Gonioscopy was performed with a Goldman goniolens in dark room first and followed by full beam light and indentation. If the filtering trabecular meshwork was invisible or any peripheral anterior synechia was found, that quadrant of the angle was considered closed. UBM was first undertaken in a darkened room then repeated with normal room lighting. If iridotrabecular apposition was showed, that quadrant of the angle was considered closed. The status of angle closure of each quadrant with different methods was recorded. 85 eyes of 46 patients were included in this study. The agreement between gonioscopy and UBM was poor (Κ<0.4) with Kappa analysis in both dark and light conditions in each quadrant. The accordance of agreement between gonioscopy and UBM was hardly affected by age or sex, while in dark condition, eyes with deeper anterior chamber (P=0.005) or plateau iris configuration tended to produce different results (P=0.075) in the 2 methods. Gonioscopy and UBM are both indispensable methods for detecting angle closure, neither can completely replace the other.

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

Is being female a risk factor for shallow anterior chamber? The associations between anterior chamber depth and age, sex, and body height

PubMed Central

Hsu, Wei-Cherng; Shen, Elizabeth P; Hsieh, Yi-Ting

2014-01-01

Aim of Study: To analyze the association between anterior chamber depth (ACD) and age, sex, and body height (BH). Materials and Methods: One thousand four hundred eighty eyes of 1480 adults 40 years of age and older receiving preoperative evaluation for cataract surgery were recruited consecutively from June 1, 2006, to December 31, 2010. ACD was measured with the Zeiss IOLMaster. Univariate and multivariate linear regression models were used to analyze the correlations, and receiving operator characteristic (ROC) curves and the area under the curve (AUC) were used for evaluating the predictability of an ACD less than 2.70 mm. Results: ACD was negatively correlated with age and positively correlated with BH in both univariate and multivariate regression analysis (P < 0.001). Sex was associated with ACD in univariate analysis, but not after adjustment with age and BH. In predicting an ACD less than 2.70 mm, the AUCs of ROC curves for ‘age and sex’, ‘age and BH’, and ‘age, sex, and BH’ were 0.687, 0.689, and 0.689, respectively. Conclusion: Age and BH were independent associating factors of ACD; however, sex was not. Older people and shorter ones likely had shallower ACD, and therefore were predisposed to Primary angle closure glaucoma (PACG). The predictability of ACD by age and BH solely was low, and adding sex did not increase it. PMID:24145564

Anterior segment morphology and morphometry in selected reptile species using optical coherence tomography.

PubMed

Rival, Franck; Linsart, Adeline; Isard, Pierre-François; Besson, Christian; Dulaurent, Thomas

2015-01-01

To provide new and original images of the anterior segment (AS) of the eye of selected Ophidian, Chelonian, and Saurian species and to compare the AS architecture among and within these three groups. 17 Saurians, 14 Ophidians, and 11 Chelonians with no concurrent systemic or eye disease were included in the study. Age, weight, nose-cloaca distance (NCD), and pupil shape were collected for each animal. The AS was examined by optical coherence tomography (OCT). After gross description of the appearance of the AS, the central and peripheral corneal thickness (CCT, PCT) and anterior chamber depth (ACD) were measured using the software provided with the OCT device. The ratio CCT/ACD was then calculated for each animal. Pupil shape was a vertical slit in all the crepuscular or nocturnal animals (except for 1 chelonian and 1 ophidian). Each group had its own particular AS architecture. Saurians had a regularly thin cornea with a flat anterior lens capsule and a deep anterior chamber. Ophidians had a thick cornea with a narrow anterior chamber due to a very anteriorly anchored spherical lens. The spectacle was difficult to identify in all ophidians except in Python molurus bivitattus in which it was more obvious. Chelonians displayed an intermediate architecture which more closely resembled the Saurian type than the Ophidian type. Despite grossly similar AS architecture, the three groups of reptiles in the study demonstrated differences that are suggestive of a link between anatomical disparities and variations in environment and lifestyle. © 2014 American College of Veterinary Ophthalmologists.

In vivo biometry in the mouse eye with low coherence interferometry.

PubMed

Schmucker, Christine; Schaeffel, Frank

2004-01-01

A major drawback of the mouse model of myopia is that the ocular dimensions cannot be measured in vivo, and that histological techniques post-mortem suffer from limited resolution. We have tested the potential of a newly developed technique, optical low coherence interferometry (OLCI), adapted for short measurement distances by Meditec, Carl Zeiss, Jena, Germany (the "ACMaster"). Using this technique, ocular biometry was performed in mice with normal vision and after deprivation of form vision. Axial eye length, corneal thickness and anterior chamber depth were measured in 23 mice, aged 25-53 days, and standard deviations from repeated measurements in the same eyes, as well as intra-individual and inter-individual variability were determined in different age groups. The data were compared to those from a preceding study in which biometrical data were obtained from frozen sections [Vision Res. 44 (2004) 1857]. Refractions were measured by automated infrared photorefraction. Mice had either normal visual exposure or were monocularly deprived of form vision for 14 days. Using OLCI, axial length could be determined with an average standard deviation of 8.0 +/- 2.9 microm, corneal thickness with 3.5 +/- 2.1 microm, and anterior chamber depth with 10.6 +/- 12.3 microm. Neither axial length, nor corneal thickness, nor anterior chamber depth were significantly different in left and right eyes of individual mice that had normal visual experience (mean absolute difference between axial lengths: 17 +/- 18 microm, between corneal thickness 5.1 +/- 4.8 microm, and between anterior chamber depths 16.7 +/- 14.8 microm). Compared to the variability that was previously found in frozen sections, the variability of axial length measurements with OLCI was 2.7 times less. After two weeks of form deprivation, OLCI revealed a significant axial elongation in the occluded eyes, compared to the contralateral fellow eyes (+38 +/- 36 microm or 1.16%, p = 0.045, n = 7, paired t-test). In this sample, no accompanying myopic shift was observed in the occluded eyes but this observation is not unexpected given the inherently variable responses of mouse eye growth to visual deprivation. OLCI had sufficient resolution in living mice to detect axial length changes in vivo that were equivalent to a dioptric change of 2 D. Using this technique, it was confirmed that mouse eyes respond to form deprivation by axial elongation, similar to the eyes of other animal models. The lack of a myopic shift in this sample, despite the axial elongation, demonstrates that biometric data are particularly important when the mouse eye is used as a model to study myopia.

Nature of the refractive errors in rhesus monkeys (Macaca mulatta) with experimentally induced ametropias.

PubMed

Qiao-Grider, Ying; Hung, Li-Fang; Kee, Chea-Su; Ramamirtham, Ramkumar; Smith, Earl L

2010-08-23

We analyzed the contribution of individual ocular components to vision-induced ametropias in 210 rhesus monkeys. The primary contribution to refractive-error development came from vitreous chamber depth; a minor contribution from corneal power was also detected. However, there was no systematic relationship between refractive error and anterior chamber depth or between refractive error and any crystalline lens parameter. Our results are in good agreement with previous studies in humans, suggesting that the refractive errors commonly observed in humans are created by vision-dependent mechanisms that are similar to those operating in monkeys. This concordance emphasizes the applicability of rhesus monkeys in refractive-error studies. Copyright 2010 Elsevier Ltd. All rights reserved.

Nature of the Refractive Errors in Rhesus Monkeys (Macaca mulatta) with Experimentally Induced Ametropias

PubMed Central

Qiao-Grider, Ying; Hung, Li-Fang; Kee, Chea-su; Ramamirtham, Ramkumar; Smith, Earl L.

2010-01-01

We analyzed the contribution of individual ocular components to vision-induced ametropias in 210 rhesus monkeys. The primary contribution to refractive-error development came from vitreous chamber depth; a minor contribution from corneal power was also detected. However, there was no systematic relationship between refractive error and anterior chamber depth or between refractive error and any crystalline lens parameter. Our results are in good agreement with previous studies in humans, suggesting that the refractive errors commonly observed in humans are created by vision-dependent mechanisms that are similar to those operating in monkeys. This concordance emphasizes the applicability of rhesus monkeys in refractive-error studies. PMID:20600237

Malignant glaucoma after cataract surgery.

PubMed

Varma, Devesh K; Belovay, Graham W; Tam, Diamond Y; Ahmed, Iqbal Ike K

2014-11-01

To report a series of eyes that developed malignant glaucoma after cataract surgery. Private academic practice, Toronto, Ontario, Canada. Retrospective case series. Eyes that developed malignant glaucoma after cataract surgery were treated with medical therapy. This was followed by laser iridozonulohyaloidotomy, anterior chamber reformation and intraocular lens (IOL) pushback, and finally with surgical iridozonulohyaloidovitrectomy if all other measures were unsuccessful. Refraction, intraocular pressure (IOP), gonioscopy, and anterior chamber depth (ACD) by anterior segment optical coherence tomography were analyzed before treatment and after treatment. The study evaluated 20 eyes of 18 female patients aged 44 to 86 years. Preoperatively, the mean refraction was +3.11 diopters (D) ± 2.89 (SD), the mean axial length was 21.30 ± 1.40 mm, and all eyes had narrow or closed angles. Malignant glaucoma was diagnosed a mean of 5.8 ± 7.1 weeks postoperatively. At diagnosis, the mean refraction was -2.15 ± 2.95 D; the mean ACD, 2.49 ± 0.72 mm; and the mean IOP, 28.3 ± 10.8 mm Hg on a mean of 1.3 ± 1.6 medications. Two eyes responded to cycloplegia, 7 to laser iridozonulohyaloidotomy, and 6 to anterior chamber reformation-IOL pushback; 5 eyes required vitrectomy. Posttreatment, the mean refraction was -0.56 ± 1.07 D; the mean ACD, 3.30 ± 0.50 mm; and the mean IOP, 14.4 ± 4.60 mm Hg on a mean of 1.2 ± 1.4 medications. Cycloplegia was discontinued in 17 eyes. Malignant glaucoma can occur after phacoemulsification and presents with myopic surprise, anterior chamber shallowing and, possibly, elevated IOP. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Anterior chamber angle assessment using gonioscopy and ultrasound biomicroscopy.

PubMed

Narayanaswamy, Arun; Vijaya, Lingam; Shantha, B; Baskaran, Mani; Sathidevi, A V; Baluswamy, Sukumar

2004-01-01

Comparison of anterior chamber angle measurements using ultrasound biomicroscopy (UBM) and gonioscopy. Five hundred subjects were evaluated for grading of angle width by the Shaffer method. UBM was done in the same group to document angle width, angle opening distance (AOD 500), and anterior chamber depth. Biometric parameters were documented in all subjects. UBM and gonioscopic findings were compared. A study was conducted in 282 men and 218 women with a mean age of 57.32 +/- 12.48 years. Gonioscopic grading was used to segregate occludable (slit-like, grades 1 and 2) from nonoccludable (grades 3 and 4) angles. Subjective assessment by gonioscopy resulted in an overestimation of angle width within the occludable group when compared with values obtained by UBM. This did not affect the segregation of occludable versus nonoccludable angles by gonioscopy. Biometric parameters in eyes with occludable angles were significantly lower in comparison with eyes with nonoccludable angles, except for lens thickness. AOD 500 correlated well with angle width. We concluded that clinical segregation into occludable and nonoccludable angles by an experienced observer using gonioscopy is fairly accurate. However, UBM is required for objective quantification of angles, and AOD 500 can be a reliable and standard parameter to grade angle width.

Ethnic differences in primary angle-closure glaucoma.

PubMed

Yip, Jennifer L Y; Foster, Paul J

2006-04-01

Observational studies from different countries have shown that populations of East Asian origin have a higher frequency of primary angle-closure glaucoma compared with those of European or African descent. As half of all cases of glaucoma reside in Asia, and with primary angle-closure glaucoma carrying a higher rate of visual morbidity, primary angle-closure glaucoma poses an important public health problem; however, the inconsistent use of techniques and definitions to detect and diagnose primary angle-closure glaucoma has resulted in difficulties in interpreting the accuracy and comparability of such data. Therefore it is important to review these studies in the light of a consistent classification system. There are increasing reports that support previous findings on the incidence and prevalence of primary angle-closure glaucoma in different ethnic groups. There have also been further investigations into the mechanism and natural history of primary angle-closure glaucoma in Asian populations. International investigations into primary angle-closure glaucoma have demonstrated reproducible evidence that ethnic variations do exist. Cross-sectional studies in this area have also suggested that differences in anterior chamber depth, together with its association with peripheral anterior synechiae, may be part of the underlying mechanism behind these differences. The ideas generated need to be further explored with longitudinal data of changes in anterior chamber depth and peripheral anterior synechiae in different populations. The detailed mechanisms behind the development of angle-closure and primary angle-closure glaucoma should also be investigated.

Clinical Analysis of Ocular Parameters Contributing to Intraoperative Pain during Standard Phacoemulsification

PubMed Central

Kim, Myung Jun

2017-01-01

Purpose. To study the correlation between ocular parameters and subjective pain that patients perceived during phacoemulsification. Methods. Medical records of 142 patients who underwent standard phacoemulsification under topical anesthesia between March and August 2016 were retrospectively reviewed. The pain during phacoemulsification and 1 h after surgery was assessed and compared using a visual analog scale. In addition, demographic data, preoperative biometric parameters, and intraoperative surgical parameters were recorded. Results. Mean age of patients was 67.49 ± 12.50 years. The mean pain score was 2.26 ± 0.85 during phacoemulsification and 0.40 ± 0.69 postoperatively. Intraoperative pain was significantly associated with higher preoperative intraocular pressure (β = 0.220, P = 0.016), greater anterior chamber depth (β = 0.210, P = 0.028), and greater axial length (β = 0.181, P = 0.043). Conclusions. To reduce the subjective pain when patients have high preoperative intraocular pressure, large anterior chamber depth, or great axial length, supplementary procedures may be required. PMID:28491473

[Screening method for angle closure and angle closure glaucoma using scanning laser polarimeter GDxVCC and photodynamic gonioscopy in a darkened room. One-year outcomes of systematic peripheral iridotomy].

PubMed

Malek-Chehire, N; Renard, G; Dreyfus, J-F; Lebuisson, D A; Pierre-Kahn, V

2013-12-01

Angle closure glaucoma, a recognized major world health issue disproportionately affecting women and Asians, is not often considered in our European populations, normotensive subjects, myopic patients, or subjects with a deep anterior chamber. Early diagnosis is worthwhile, as laser peripheral iridotomy (LPI) is an effective one-step treatment of the causal mechanism. We have performed a retrospective study of patients who underwent an LPI, the indication for which was based on "photodynamic" gonioscopy in a darkened room showing iridotrabecular contact in darkness. Such photodynamic gonioscopy was motivated by the presence of even minute defects in the nerve fiber layer as seen on the GDxVCC or the presence of a Van Herick sign (narrow limbal anterior chamber depth). One hundred and three eyes of 103 patients underwent LPI and a minimum 1-year follow-up (mean follow-up almost 2 years). Mean age was 63.7±11.8 years, and women accounted for 63.1% of cases. The vast majority (78.6%) of patients had neither glaucoma nor ocular hypertension. There were 60.1% hyperopes and 39.9% myopes. Over half (57%) had a deep or a very deep anterior chamber. After LPI, there was immediate deepening of the limbal depth of the anterior chamber in 100% of cases. The aqueous humor that flowed forward was almost always viscous-looking. After 1 year, the IOP was 1.3mm Hg±2.4 lower (P<.001) (t test). All patients who had experienced morning headaches (44% of patients) were relieved of this symptom. GDxVCC after 1 year was clearly improved in 18% of cases, slightly improved in 20%, stable in 50%, slightly worse in 11% of cases, and clearly worse in 1%. Cases treated at an earlier stage had a better improvement in GDxVCC. Our study shows frequent chronic angle closure in our European population even with deep anterior chambers. Absence of a Van Herick sign does not rule out angle closure at night. A photodynamic gonioscopy with the Goldmann three-lens mirror (to avoid unintentional indentation with the small diameter lenses in these normotensive eyes) should be performed in a darkened room. LPI is an effective one-step treatment of the underlying cause, that is particularly beneficial if performed early. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Biometric parameters in different stages of primary angle closure using low-coherence interferometry.

PubMed

Yazdani, Shahin; Akbarian, Shadi; Pakravan, Mohammad; Doozandeh, Azadeh; Afrouzifar, Mohsen

2015-03-01

To compare ocular biometric parameters using low-coherence interferometry among siblings affected with different degrees of primary angle closure (PAC). In this cross-sectional comparative study, a total of 170 eyes of 86 siblings from 47 families underwent low-coherence interferometry (LenStar 900; Haag-Streit, Koeniz, Switzerland) to determine central corneal thickness, anterior chamber depth (ACD), aqueous depth (AD), lens thickness (LT), vitreous depth, and axial length (AL). Regression coefficients were applied to show the trend of the measured variables in different stages of angle closure. To evaluate the discriminative power of the parameters, receiver operating characteristic curves were used. Best cutoff points were selected based on the Youden index. Sensitivity, specificity, positive and negative predicative values, positive and negative likelihood ratios, and diagnostic accuracy were determined for each variable. All biometric parameters changed significantly from normal eyes to PAC suspects, PAC, and PAC glaucoma; there was a significant stepwise decrease in central corneal thickness, ACD, AD, vitreous depth, and AL, and an increase in LT and LT/AL. Anterior chamber depth and AD had the best diagnostic power for detecting angle closure; best levels of sensitivity and specificity were obtained with cutoff values of 3.11 mm for ACD and 2.57 mm for AD. Biometric parameters measured by low-coherence interferometry demonstrated a significant and stepwise change among eyes affected with various degrees of angle closure. Although the current classification scheme for angle closure is based on anatomical features, it has excellent correlation with biometric parameters.

Does Dry Eye Affect Repeatability of Corneal Topography Measurements?

PubMed

Doğan, Aysun Şanal; Gürdal, Canan; Köylü, Mehmet Talay

2018-04-01

The purpose of this study was to assess the repeatability of corneal topography measurements in dry eye patients and healthy controls. Participants underwent consecutive corneal topography measurements (Sirius; Costruzione Strumenti Oftalmici, Florence, Italy). Two images with acquisition quality higher than 90% were accepted. The following parameters were evaluated: minimum and central corneal thickness, aqueous depth, apex curvature, anterior chamber volume, horizontal anterior chamber diameter, iridocorneal angle, cornea volume, and average simulated keratometry. Repeatability was assessed by calculating intra-class correlation coefficient. Thirty-three patients with dry eye syndrome and 40 healthy controls were enrolled to the study. The groups were similar in terms of age (39 [18-65] vs. 30.5 [18-65] years, p=0.198) and gender (M/F: 4/29 vs. 8/32, p=0.366). Intra-class correlation coefficients among all topography parameters within both groups showed excellent repeatability (>0.90). The anterior segment measurements provided by the Sirius corneal topography system were highly repeatable for dry eye patients and are sufficiently reliable for clinical practice and research.

[Two cases of Vogt-Koyanagi-Harada disease presenting shallow anterior chamber].

PubMed

Takemoto, Daisuke; Ijiri, Shigeyuki; Shimizu, Michiharu; Higashide, Tomomi; Sugiyama, Kazuhisa

2015-05-01

We report two cases of Vogt-Koyanagi-Harada disease (VKH) in which shallow anterior chambers were improved after steroid pulse therapy. The patients were women aged 65 and 72. They had headaches, decreased visual acuity and shallow anterior chamber in both eyes. There was no inflammation in the anterior chamber. Ultrasound biomicroscopy (UBM) showed ciliary edema, ciliochoroidal detachment, and angle closure. One case showed high intraocular pressure (IOP), and a diagnosis of acute primary angle closure was made. Although cataract surgery was performed in the left eye, postoperative optical coherence tomography (OCT) revealed serous retinal detachment in both eyes. The shallow anterior chamber and UBM findings were improved and serous retinal detachment disappeared after steroid pulse therapy in both cases. VKH may cause shallow anterior chamber and angle closure. The inflammatory changes of VKH in the anterior segment, i. e. ciliary edema and ciliochoroidal detachment, may exacerbate the shallow anterior chambers and narrow angles and result in an acute increase in IOP in eyes with short axial length. VKH associated with shallow anterior chamber may be misdiagnosed as acute primary angle closure. For differential diagnosis, examinations of the ocular fundus including OCT are useful.

Axial length changes after retinal detachment surgery.

PubMed

Burton, T C; Herron, B E; Ossoinig, K C

1977-01-01

A-scan echography was an accurate method for detecting changes in the depth of the anterior chamber, lens thickness, and length of the vitreous cavity after retinal detachment surgery in 30 eyes. Approximately 60% of the eyes had significant alterations in axial lengths exceeding+/-0.36 mm in aphakic eyes and +/-0.54 mm in phakic eyes. However, the operation of scleral bucklingg with large segments of hard silicone rubber implants or explants supported by an encircling band failed to result in a significant predictable shift of axial change in phakic or aphakic eyes. A-scan echography showed significant shallowing of the anterior chamber, and scleral buckling significantly increases lens thickness for at least six weeks. This induced a minor myopic refractive change that may explain some of the difference in postoperative refracitons between phakic and aphakic eyes.

Preoperative Biometric Parameters Predict the Vault after ICL Implantation: A Retrospective Clinical Study.

PubMed

Zheng, Qian-Yin; Xu, Wen; Liang, Guan-Lu; Wu, Jing; Shi, Jun-Ting

2016-01-01

To investigate the correlation between the preoperative biometric parameters of the anterior segment and the vault after implantable Collamer lens (ICL) implantation via this retrospective study. Retrospective clinical study. A total of 78 eyes from 41 patients who underwent ICL implantation surgery were included in this study. Preoperative biometric parameters, including white-to-white (WTW) diameter, central corneal thickness, keratometer, pupil diameter, anterior chamber depth, sulcus-to-sulcus diameter, anterior chamber area (ACA) and central curvature radius of the anterior surface of the lens (Lenscur), were measured. Lenscur and ACA were measured with Rhinoceros 5.0 software on the image scanned with ultrasound biomicroscopy (UBM). The vault was assessed by UBM 3 months after surgery. Multiple stepwise regression analysis was employed to identify the variables that were correlated with the vault. The results showed that the vault was correlated with 3 variables: ACA (22.4 ± 4.25 mm2), WTW (11.36 ± 0.29 mm) and Lenscur (9.15 ± 1.21 mm). The regressive equation was: vault (mm) = 1.785 + 0.017 × ACA + 0.051 × Lenscur - 0.203 × WTW. Biometric parameters of the anterior segment (ACA, WTW and Lenscur) can predict the vault after ICL implantation using a new regression equation. © 2016 The Author(s) Published by S. Karger AG, Basel.

Phakic Intraocular Lens Implantation: Refractive Outcome and Safety in Patients with Anterior Chamber Depth between 2.8 and 3.0 versus ≥3.0 mm.

PubMed

Guerra, Marta G; Silva, Andreia M M; Marques, Sara H M; Melo, Sofia H; Póvoa, João A; Lobo, Conceição; Murta, Joaquim Neto

2017-01-01

To compare endothelial cell (EC) variation after anterior chamber phakic intraocular lens (AC-pIOL) implantation in highly myopic patients with a preoperative anterior chamber depth (ACD) between 2.8 and 3.0 versus ≥3.0 mm. A total of 280 eyes submitted to primary AC-pIOL implantation were analyzed. Pre- and postoperative values for uncorrected distance visual acuity, corrected distance visual acuity, spherical equivalent, ACD (endothelial surface), and EC count were collected. The eyes were divided into 2 groups: group A - ACD between 2.8 and 3.0 mm; group B - ACD ≥3.0 mm. Mean global EC loss (ECL) and loss for each ACD group, according to pIOL type, were analyzed. Significant improvement of the spherical equivalent (-11.38 ± 4.57 vs. -0.49 ± 0.79; p = 0.000) and a significant decrease in EC density (2,810.95 ± 343.88 vs. 2,584.09 ± 374.88 cells/mm2; p = 0.000) were noted. The mean annual ECL was -2.19 ± 3.97%. Regarding group A (n = 80), a mean annual ECL of -2.06 ± 3.88% was registered, higher for the Acrysof Cachet® subtype, while group B (n = 200) showed -2.25 ± 4.01% ECL, higher for the Verisyse® subtype. There was no significant difference between the groups (p = 0.96). AC-pIOL implantation significantly improves the spherical equivalent in myopic patients. The mean annual ECL after pIOL implantation was higher in the larger ACD group, but this value was not statistically significant. A 2.8-mm ACD value seems to be a safe cutoff for AC-pIOL implantation. © 2017 S. Karger AG, Basel.

Impact of the Femtosecond Laser in Line with the Femtosecond Laser-Assisted Cataract Surgery (FLACS) on the Anterior Chamber Characteristics in Comparison to the Manual Phacoemulsification.

PubMed

Pahlitzsch, Milena; Torun, Necip; Pahlitzsch, Marie Luise; Klamann, Matthias K J; Gonnermann, Johannes; Bertelmann, Eckart; Pahlitzsch, Thomas

2017-01-01

To assess the alterations of the anterior chamber conditions including laser flare photometry after femtosecond laser-assisted cataract surgery (FLACS) compared to the manual phacoemulsification. Data of n=70 FLACS (mean age 67.2 ± 8.9 years) and n=40 manual phacoemulsification (mean age 69.5 ± 9.6 years) were analyzed. The procedures were performed by LenSx Alcon, USA, and Alcon Infiniti Vision System, USA. The following parameters were recorded: laser flare photometry (Kowa FM 700, Japan), anterior chamber (AC) depth, AC volume, AC angle (Pentacam, Oculus Inc., Germany), lens density, pupil diameter, endothelial cell count and pachymetry. The analysis was performed preoperatively, immediately after femtosecond laser procedure and one day postoperatively. Between FLACS and the phaco control group, there was a significant difference in the AC depth (p=0.023, 3.77 mm vs. 4.05 mm) one day postoperatively. The AC angle (p=0.016) showed a significant difference immediately after the femto laser treatment. The central and thinnest pachymetry and endothelial cell count did not show a significant difference between the two study cohorts (p=0.165, p=0.291, p=0.979). The phaco cohort (n=40) demonstrated a non-statistically significant difference in the flare photometry of 15.80 photons/ms one postoperative day compared to the FLACS group 26.62 photons/ms (p=0.322). In this study population, no evidence for an additive damage caused by the use of the femtosecond laser was demonstrated. Furthermore, no increase in the central and thinnest corneal thickness and no increased endothelial cell loss was demonstrated by the laser energy.

Rabbit cornea microstructure response to changes in intraocular pressure visualized by using nonlinear optical microscopy.

PubMed

Wu, Qiaofeng; Yeh, Alvin T

2008-02-01

To characterize the microstructural response of the rabbit cornea to changes in intraocular pressure (IOP) by using nonlinear optical microscopy (NLOM). Isolated rabbit corneas were mounted on an artificial anterior chamber in series with a manometer and were hydrostatically pressurized by a reservoir. The chamber was mounted on an upright microscope stage of a custom-built NLOM system for corneal imaging without using exogenous stains or dyes. Second harmonic generation in collagen was used to image through the full thickness of the central corneal stroma at IOPs between 5 and 20 mm Hg. Microstructural morphology changes as a function of IOP were used to characterize the depth-dependent response of the central cornea. Regional collagen lamellae architecture through the full thickness of the stroma was specifically imaged as a function of IOP. Hypotensive corneas showed gaps between lamellar structures that decreased in size with increasing IOP. These morphologic features appear to result from interwoven lamellae oriented along the anterior-posterior axis and parallel to the cornea surface. They appear throughout the full thickness and disappear with tension in the anterior but persist in the posterior central cornea, even at hypertensive IOP. NLOM reveals interwoven collagen lamellae sheets through the full thickness of the rabbit central cornea oriented along the anterior-posterior axis and parallel to the surface. The nondestructive nature of NLOM allows 3-dimensional imaging of stromal architecture as a function of IOP in situ. Collagen morphologic features were used as an indirect measure of depth-dependent mechanical response to changes in IOP.

Refractive states of eyes and associations between ametropia and age, breed, and axial globe length in domestic cats.

PubMed

Konrade, Kricket A; Hoffman, Allison R; Ramey, Kelli L; Goldenberg, Ruby B; Lehenbauer, Terry W

2012-02-01

To determine the refractive states of eyes in domestic cats and to evaluate correlations between refractive error and age, breed, and axial globe measurements. 98 healthy ophthalmologically normal domestic cats. The refractive state of 196 eyes (2 eyes/cat) was determined by use of streak retinoscopy. Cats were considered ametropic when the mean refractive state was ≥ ± 0.5 diopter (D). Amplitude-mode ultrasonography was used to determine axial globe length, anterior chamber length, and vitreous chamber depth. Mean ± SD refractive state of all eyes was -0.78 ± 1.37 D. Mean refractive error of cats changed significantly as a function of age. Mean refractive state of kittens (≤ 4 months old) was -2.45 ± 1.57 D, and mean refractive state of adult cats (> 1 year old) was -0.39 ± 0.85 D. Mean axial globe length, anterior chamber length, and vitreous chamber depth were 19.75 ± 1.59 mm, 4.66 ± 0.86 mm, and 7.92 ± 0.86 mm, respectively. Correlations were detected between age and breed and between age and refractive states of feline eyes. Mean refractive error changed significantly as a function of age, and kittens had greater negative refractive error than did adult cats. Domestic shorthair cats were significantly more likely to be myopic than were domestic mediumhair or domestic longhair cats. Domestic cats should be included in the animals in which myopia can be detected at a young age, with a likelihood of progression to emmetropia as cats mature.

[Multifocal phakic intraocular lens implant to correct presbyopia].

PubMed

Baikoff, G; Matach, G; Fontaine, A; Ferraz, C; Spera, C

2005-03-01

Presbyopic surgery is considered as the new frontier in refractive surgery. Different solutions are proposed: myopization of one eye, insertion of an accommodative crystalline lens, scleral surgery, the effects of which are still unknown, and finally multifocal phakic implants. We therefore decided to undertake a prospective study under the Huriet law to determine its efficacy and specify the conditions required for an anterior chamber multifocal phakic implant. Fifty-five eyes of 33 patients received an anterior chamber foldable multifocal phakic implant. Twenty-one females and 12 males underwent surgery. Initial refraction was between -5D and +5D. The implant's single addition was +2.50. Recuperating a distant uncorrected visual acuity of 0.6 or better and near uncorrected vision of Parinaud 3 or better can be considered a very good postoperative result. Average follow-up was 42.6+/-18 weeks. Mean postoperative refraction was -0.12+/-0.51 D. Mean postoperative uncorrected visual acuity was 0.78+/-0.20. Postoperative uncorrected visual acuity was Parinaud 2.3+/-0.6. Eighty-four percent of eyes operated on recuperated 0.6 or better without correction and Parinaud 3 or better without correction. Lenses in four eyes were explanted for different reasons, essentially optical, and no severe anatomical complications were observed. Placing an anterior chamber multifocal phakic implant to correct presbyopia is an effective technique with good predictability and has the advantage of being reversible in case of intolerance, optical parasite effects or undesired complications. Considering the particularity of this surgery, it is imperative to respect very strict inclusion criteria: anterior chamber depth equal to or above 3.1 mm, open angle, endothelial cell count equal to or above 2000 cells/mm2, absence of an incipient cataract or the slightest evidence of macular alteration.

Modeling the drug transport in the anterior segment of the eye.

PubMed

Avtar, Ram; Tandon, Deepti

2008-10-02

The aim of the present work is the development of a simple mathematical model for the time course concentration profile of topically administered drugs in the anterior chamber aqueous humor and investigation of the effects of various model parameters on the aqueous humor concentration of lipophilic and hydrophilic drugs. A simple pharmacokinetic model for the transient drug transport in the anterior segment has been developed by using the conservation of mass in the precorneal tear film, Fick's law of diffusion and Michaelis-Menten kinetics of drug metabolism in cornea, and the conservation of mass in the anterior chamber. An analytical solution describing the drug concentration in the anterior chamber has been obtained. The model predicts that an increase in the drug metabolic (consumption) rate in the corneal epithelium reduces the drug concentration in the anterior chamber for both lipophilic and hydrophilic molecules. A decrease in the clearance rate and distribution volume of the drug in the anterior chamber raises the aqueous humor concentration significantly. It is also observed that decay rate of drug concentration in the anterior chamber is higher for lipophilic molecules than that for hydrophilic molecules. The bioavailability of drugs applied topically to the eye may be improved by a rise in the precorneal tear volume, diffusion coefficient in corneal epithelium and distribution coefficient across the endothelium anterior chamber interface, and by reducing the drug metabolism, drug clearance rate and distribution volume in anterior chamber.

The Relationship Between High-Order Aberration and Anterior Ocular Biometry During Accommodation in Young Healthy Adults

PubMed Central

Ke, Bilian; Mao, Xinjie; Jiang, Hong; He, Jichang; Liu, Che; Li, Min; Yuan, Ying

2017-01-01

Purpose This study investigated the anterior ocular anatomic origin of high-order aberration (HOA) components using optical coherence tomography and a Shack-Hartmann wavefront sensor. Methods A customized system was built to simultaneously capture images of ocular wavefront aberrations and anterior ocular biometry. Relaxed, 2-diopter (D) and 4-D accommodative states were repeatedly measured in 30 young subjects. Custom software was used to correct optical distortions and measure biometric parameters from the images. Results The anterior ocular biometry changed during 2-D accommodation, in which central lens thickness, ciliary muscle thicknesses at 1 mm posterior to the scleral spur (CMT1), and the maximum value of ciliary muscle thickness increased significantly, whereas anterior chamber depth, CMT3, radius of anterior lens surface curvature (RAL), and radius of posterior lens surface curvature (RPL) decreased significantly. The changes in the anterior ocular parameters during 4-D accommodation were similar to those for the 2-D accommodation. \\begin{document}\

Bilateral spontaneous crystalline lens dislocation to the anterior chamber: a case report.

PubMed

Jovanović, Milos

2013-01-01

There are various reasons for the lens dislocation. Spontaneous dislocation of a clear lens is extremely rare, especially its dislocation to the anterior chamber. The author presents a case of spontaneous clear lens dislocation to the anterior chamber in both eyes in a patient without the history of any trauma. Dislocation occurred spontaneously, first in the left eye, along with a sudden decrease of vision. The ophthalmologist found a clear lens in the anterior chamber, without any sign of an elevated intraocular pressure, as should have been expected. The dislocated lens was removed surgically (intracapsular extraction) with the preventive basal iridectomy. Two years later, the same happened in the right eye: clear lens moved spontaneously to the anterior chamber, with a decrease of vision, but again without any rise of intraocular pressure and/or any pain. Intracapsular extraction of the lens with basal iridectomy was done again. The presented case demonstrates that spontaneous dislocation of the transparent lens to the eye anterior chamber can occur in both eyes at different time intervals. We suggest the removal of dislocated lens in the anterior chamber by the intracapsular extraction.

The efficacy of bromfenac ophthalmic solution 0.07% dosed once daily in achieving zero-to-trace anterior chamber cell severity following cataract surgery

PubMed Central

Silverstein, Steven M; Jackson, Mitchell A; Goldberg, Damien F; Muñoz, Mauricio

2014-01-01

Purpose To evaluate the efficacy of bromfenac ophthalmic solution 0.07% dosed once daily in achieving zero-to-trace (0–5 cells) anterior chamber cells, following cataract surgery with posterior chamber intraocular lens implantation. Methods The study designed employed two Phase III, double-masked, placebo-controlled, multicenter clinical trials of 440 subjects, randomized to either bromfenac ophthalmic solution 0.07% (n=222) or placebo (n=218). Subjects self-dosed once daily, beginning 1 day before undergoing cataract surgery with intraocular lens implantation (day –1) and again on the day of surgery (day 0) and for 14 days postoperatively. Follow-up was on days 1, 3, 8, and 15. The outcome measures included the percentage of subjects with zero-to-trace anterior chamber cells at each visit, as determined by the percentage of subjects with ≤5 anterior chamber cells, overall anterior chamber cell grades, and summed ocular inflammation score (SOIS) (combined anterior chamber cell and flare scores). Results The proportion of subjects with zero-to-trace anterior chamber cells was significantly higher in the bromfenac 0.07% group compared with the placebo group as early as day 3 (P=0.0007), continued at day 8 (P<0.0001), and through day 15 (P<0.0001). At day 15, 80.2% of subjects in the bromfenac 0.07% group achieved zero-to-trace anterior chamber cells compared with 47.2% of subjects who did so in the placebo group. The overall anterior chamber cell scores were significantly lower in the bromfenac 0.07% group compared with the placebo group at days 3, 8, and 15 (P<0.0001 at each visit). The SOIS were also significantly lower in the bromfenac group compared with the placebo group at days 3, 8, and 15 (P<0.0001 at each visit). Conclusion Bromfenac ophthalmic solution 0.07%, dosed once daily was clinically effective in achieving zero-to-trace anterior chamber cell severity after cataract surgery and was superior to placebo in all anterior chamber cell severity and inflammation outcome measures. PMID:24876763

[Changes of axial dimensions of the eye during growth in emmetropia, myopia and hyperopia].

PubMed

Katuzny, Bartłomiej J; Koszewska-Kołodziejczak, Aleksandra

2005-01-01

The aim ot this study was to evaluate changes ot axial dimensions ot the eye during growth in emmetropia, myopia and hyperopia. We examined 183 children (363 eyes) aged 4 to 19 with emmetropia, myopia and hyperopia. All measurements were performed after cycloplegia with 1% tropicamidum (Polfa Warszawa). Total and corneal refraction was examined with autokeratorefractometer (Nikon NRK-8000). Then we used ultrasound biometer Ocuscan (Alcon, USA), to measure axial length of the eye, axial length of the vitreous cavity, axial dimension of the lens and axial depth of the anterior chamber. 1. Growth of the axial length of the emmetropic eyes is finished at the age of 12, in hyperopic eyes in the age of 11 and in myopic eyes growth is proportional until the age of 14 and then significantly accelerates. 2. Growth of the axial length is mainly caused by increasing axial length of vitreous cavity. A little role in human eye growth is also played by increasing depth of the anterior chamber. 3. Between 4 and 19 years old, mean cycloplegic axial dimension of the lens is slightly decreasing in emmetropic and hyperopic eyes, whereas in myopic eyes is constant.

Correlation between ocular parameters and amplitude of accommodation

PubMed Central

Abraham, Lekha Mary; Kuriakose, Thomas; Sivanandam, Viswanathan; Venkatesan, Nithya; Thomas, Ravi; Muliyil, Jayaprakash

2010-01-01

Aim: To study the relationship between ocular parameters and amplitude of accommodation (AA) in the peri-presbyopic age group (35–50 years). Materials and Methods: Three hundred and sixteen right eyes of consecutive patients in the age group 35–50 years, who attended our outpatient clinic, were studied. Emmetropes, hypermetropes and myopes with best-corrected visual acuity of 20/20, J1 in both eyes were included. The AA was calculated by measuring the near point of accommodation. The axial length (AL), central anterior chamber depth (CACD) and lens thickness (LT) were also measured. Results: There was moderate correlation (Pearson’s correlation coefficient r = 0.56) between AL and AA as well as between CACD and AA (r = 0.53) in myopes in the age group 35–39 years. In the other age groups and the groups taken as a whole, there was no correlation. In hypermetropes and emmetropes, there was no correlation between AA and the above ocular parameters. No significant correlation existed between LT and AA across different age groups and refractive errors. Conclusion: There was no significant correlation between AA and ocular parameters like anterior chamber depth, AL and LT. PMID:20952831

Comparing approaches to screening for angle closure in older Chinese adults

PubMed Central

Andrews, J; Chang, D S; Jiang, Y; He, M; Foster, P J; Munoz, B; Kashiwagi, K; Friedman, D S

2012-01-01

Aims Primary angle-closure glaucoma is expected to account for nearly 50% of bilateral glaucoma blindness by 2020. This study was conducted to assess the performance of the scanning peripheral anterior chamber depth analyzer (SPAC) and limbal anterior chamber depth (LACD) as screening methods for angle closure. Methods This study assessed two clinical populations to compare SPAC, LACD, and gonioscopy: the Zhongshan Angle-closure Prevention Trial, from which 370 patients were eligible as closed-angle participants and the Liwan Eye Study, from which 72 patients were selected as open-angle controls. Eligible participants were assessed by SPAC, LACD, and gonioscopy. Results Angle status was defined by gonioscopy. Area under the receiver operating characteristic curve (AUROC) for SPAC was 0.92 (0.89–0.95) whereas AUROC for LACD was 0.94 (0.92–0.97). Using conventional cutoff points, sensitivity/specificity was 93.0%/70.8% for SPAC and 94.1%/87.5% for LACD. Sequential testing using both SPAC and LACD increased the specificity to 94.4% and decreased the sensitivity to 87.0%. Conclusion SPAC has significantly lower specificity than LACD measurement using conventional cutoffs but interpretation of the findings can be performed by modestly trained personnel. PMID:21997356

Accuracy of a new partial coherence interferometry analyser for biometric measurements.

PubMed

Holzer, M P; Mamusa, M; Auffarth, G U

2009-06-01

Precise biometry is an essential preoperative measurement for refractive surgery as well as cataract surgery. A new device based on partial coherence interferometry technology was tested and evaluated for accuracy of measurements. In a prospective study 200 eyes of 100 healthy phakic volunteers were examined with a functional prototype of the new ALLEGRO BioGraph (Wavelight AG)/LENSTAR LS 900 (Haag Streit AG) biometer and with the IOLMaster V.5 (Carl Zeiss Meditec AG). As recommended by the manufacturers, repeated measurements were performed with both devices and the results compared using Spearman correlation calculations (WinSTAT). Spearman correlation showed high correlations for axial length and keratometry measurements between the two devices tested. Anterior chamber depth, however, had a lower correlation between the two biometry devices. In addition, the mean values of the anterior chamber depth differed (IOLMaster 3.48 (SD 0.42) mm versus BioGraph/LENSTAR 3.64 (SD 0.26) mm); however, this difference was not statistically different (p>0.05, t test). The new biometer provided results that correlated very well with those of the IOLMaster. The ALLEGRO BioGraph/LENSTAR LS 900 is a precise device containing additional features that will be helpful tools for any cataract or refractive surgeon.

Method for measuring anterior chamber volume by image analysis

NASA Astrophysics Data System (ADS)

Zhai, Gaoshou; Zhang, Junhong; Wang, Ruichang; Wang, Bingsong; Wang, Ningli

2007-12-01

Anterior chamber volume (ACV) is very important for an oculist to make rational pathological diagnosis as to patients who have some optic diseases such as glaucoma and etc., yet it is always difficult to be measured accurately. In this paper, a method is devised to measure anterior chamber volumes based on JPEG-formatted image files that have been transformed from medical images using the anterior-chamber optical coherence tomographer (AC-OCT) and corresponding image-processing software. The corresponding algorithms for image analysis and ACV calculation are implemented in VC++ and a series of anterior chamber images of typical patients are analyzed, while anterior chamber volumes are calculated and are verified that they are in accord with clinical observation. It shows that the measurement method is effective and feasible and it has potential to improve accuracy of ACV calculation. Meanwhile, some measures should be taken to simplify the handcraft preprocess working as to images.

Biometric Factors Associated With Acute Primary Angle Closure: Comparison of the Affected and Fellow Eye.

PubMed

Atalay, Eray; Nongpiur, Monisha E; Baskaran, Mani; Sharma, Sourabh; Perera, Shamira A; Aung, Tin

2016-10-01

To compare ocular biometric and anterior segment parameters between the affected and fellow eye in subjects with acute primary angle closure (APAC). We evaluated 76 subjects with unilateral APAC who had undergone bilateral laser peripheral iridotomy before enrollment. Imaging was done using anterior segment optical coherence tomography and a customized software was used to measure the following: angle opening distance (AOD750); trabecular-iris space area (TISA750); iris thickness (IT750); iris curvature (ICURV); iris area (IAREA); anterior chamber depth; area and volume (ACD; ACA and ACV); anterior chamber width (ACW); anterior vault (ACD+LV); lens vault (LV); and pupil diameter (PD). We used A-scan ultrasonography to measure axial length (AL) and lens thickness (LT). Mean differences in ocular biometric and anterior segment parameters were assessed using linear mixed model adjusting for PD. A total of 53 subjects (36 females, 67.9%) with a mean age of 62.7 ± 8.1 years were analyzed after excluding 17 unanalyzable images in at least one eye. Affected eyes had shallower ACD, smaller ACA, ACV, anterior vault, TISA750, AOD750, and ICURV (all P < 0.05). Axial length, ACW, LV, LT, IAREA, and IT750 did not differ between the eyes. In the affected eyes, IT750 was significantly associated AOD750 (P < 0.05); whereas in the fellow eyes, IT750 and AL was predictive of AOD750 (all P < 0.05). Eyes with previous APAC had smaller anterior segment dimensions when compared with their fellow eyes. Iris thickness was the strongest predictor of angle width in both affected and fellow eyes.

Altered Anterior Segment Biometric Parameters in Mice Deficient in SPARC.

PubMed

Ho, Henrietta; Htoon, Hla M; Yam, Gary Hin-Fai; Toh, Li Zhen; Lwin, Nyein Chan; Chu, Stephanie; Lee, Ying Shi; Wong, Tina T; Seet, Li-Fong

2017-01-01

Secreted protein acidic and rich in cysteine (SPARC) and Hevin are structurally related matricellular proteins involved in extracellular matrix assembly. In this study, we compared the anterior chamber biometric parameters and iris collagen properties in SPARC-, Hevin- and SPARC-/Hevin-null with wild-type (WT) mice. The right eyes of 53 WT, 35 SPARC-, 56 Hevin-, and 63 SPARC-/Hevin-null mice were imaged using the RTVue-100 Fourier-domain optical coherence tomography system. The parameters measured were anterior chamber depth (ACD), trabecular-iris space area (TISA), angle opening distance (AOD), and pupil diameter. Biometric data were analyzed using analysis of covariance and adjusted for age, sex, and pupil diameter. Expression of Col1a1, Col8a1, and Col8a2 transcripts in the irises was measured by quantitative polymerase chain reaction. Collagen fibril thickness was evaluated by transmission electron microscopy. Mice that were SPARC- and SPARC-/Hevin-null had 1.28- and 1.25-fold deeper ACD, 1.45- and 1.53-fold larger TISA, as well as 1.42- and 1.51-fold wider AOD than WT, respectively. These measurements were not significantly different between SPARC- and SPARC-/Hevin-null mice. The SPARC-null iris expressed lower Col1a1, but higher Col8a1 and Col8a2 transcripts compared with WT. Collagen fibrils in the SPARC- and SPARC-/Hevin-null irises were 1.5- and 1.7-fold thinner than WT, respectively. The Hevin-null iris did not differ from WT in these collagen properties. SPARC-null mice have deeper anterior chamber as well as wider drainage angles compared with WT. Therefore, SPARC plays a key role in influencing the spatial organization of the anterior segment, potentially via modulation of collagen properties, while Hevin is not likely to be involved.

Single-shot dimension measurements of the mouse eye using SD-OCT.

PubMed

Jiang, Minshan; Wu, Pei-Chang; Fini, M Elizabeth; Tsai, Chia-Ling; Itakura, Tatsuo; Zhang, Xiangyang; Jiao, Shuliang

2012-01-01

The authors demonstrate the feasibility and advantage of spectral-domain optical coherence tomography (SD-OCT) for single-shot ocular biometric measurement during the development of the mouse eye. A high-resolution SD-OCT system was built for single-shot imaging of the whole mouse eye in vivo. The axial resolution and imaging depth of the system are 4.5 μm (in tissue) and 5.2 mm, respectively. The system is capable of acquiring a cross-sectional OCT image consisting of 2,048 depth scans in 85 ms. The imaging capability of the SD-OCT system was validated by imaging the normal ocular growth and experimental myopia model using C57BL/6J mice. The biometric dimensions of the mouse eye can be calculated directly from one snapshot of the SD-OCT image. The biometric parameters of the mouse eye including axial length, corneal thickness, anterior chamber depth, lens thickness, vitreous chamber depth, and retinal thickness were successfully measured by the SD-OCT. In the normal ocular growth group, the axial length increased significantly from 28 to 82 days of age (P < .001). The lens thickness increased and the vitreous chamber depth decreased significantly during this period (P < .001 and P = .001, respectively). In the experimental myopia group, there were significant increases in vitreous chamber depth and axial length in comparison to the control eyes (P = .040 and P < .001, respectively). SD-OCT is capable of providing single-shot direct, fast, and high-resolution measurements of the dimensions of young and adult mouse eyes. As a result, SD-OCT is a potentially powerful tool that can be easily applied to research in eye development and myopia using small animal models. Copyright 2012, SLACK Incorporated.

Intraocular pressure, ultrasonographic and echobiometric findings of juvenile Yacare caiman (Caiman yacare) eye.

PubMed

Ruiz, Thaís; Campos, Wilma N S; Peres, Thalita P S; Gonçalves, Gentil F; Ferraz, Rosa H S; Néspoli, Pedro E B; Sousa, Valéria R F; Ribeiro, Alexandre P

2015-01-01

The aim was to determine the intraocular pressure (IOP), the ultrasonographic and echobiometric findings in the eyes of juvenile Yacare caiman (Caiman yacare). Twenty-two healthy caimans from a breeding farm in Brazilian Pantanal. Intraocular pressure was measured under physical restraint and topical anesthesia by applanation tonometry. Five individual measurements of each eye were recorded by the same examiner. B-mode ultrasonography was performed with a 10-MHz linear transducer, and the anterior chamber depth, lens thickness, vitreous depth, and axial globe length were measured. Unpaired and paired t-tests were used to assess data. Pearson's test was used to assess correlations between IOP and ocular structures (P < 0.05). Mean ± SD IOP of the 44 eyes studied was 9.56 ± 2.69 mmHg, (range 5.4-15.6 mmHg). IOP did not differ significantly between right and left eyes or between genders (P > 0.05). Echobiometric measurements did not differ significantly between eyes and genders (P > 0.05). Intraocular structures measured in male and female subjects were, respectively, 2.61 ± 0.13 and 2.55 ± 0.18 mm for anterior chamber depth, 7.60 ± 0.17 and 7.54 ± 0.20 mm for lens thickness, 6.83 ± 0.20 and 6.90 ± 0.22 mm for vitreous chamber depth, and 17.55 ± 0.25 and 17.54 ± 0.29 mm for axial globe length. Correlations were not observed (P > 0.05). Reference values of tonometry and distances of intraocular structures of Yacare caiman were described. IOP did not correlate with echobiometric measurements in this crocodilian. The ultrasonographic appearance was similar to other domestic and wild species. © 2014 American College of Veterinary Ophthalmologists.

Gadolinium-enhanced 7.0 T magnetic resonance imaging assessment of the aqueous inflow in rat eyes in vivo.

PubMed

Li, Lu; Yuan, Yuxiang; Chen, Liwen; Li, Mu; Ji, Pingting; Gong, Jieling; Zhao, Yin; Zhang, Hong

2017-09-01

The goal of this study was to calculate the anterior chamber volume and assess aqueous inflow in rat eyes in vivo, under anesthetic condition. Gadolinium-contrast agent (Gd-DTPA, 234.5 mg/ml) was administered to Sprague-Dawley rat eyes via anterior chamber injection or instillation of 234.5 or 117.25 mg/ml Gd-DTPA in 0.2% azone as eye drops, and changes of Gd signal visualized by 7.0 T magnetic resonance imaging (MRI). The safety of local application of Gd-DTPA and azone were performed after MRI scanning. The anterior chamber injection of Gd-DTPA (234.5 mg/ml) group was used for anterior chamber volume and aqueous inflow calculating. Serial changes in Gd-DTPA relative concentration in the anterior chamber was determined based on the initial Gd signal gray values and the initial relative concentration of Gd-DTPA after anterior chamber Gd-DTPA injection. The mean aqueous inflow in rat eyes in vivo was assessed based on changes in Gd-DTPA relative concentration and the anterior chamber volume. Eye drops of Gd-DTPA (234.5 mg/ml) in 0.2% azone readily allowed safe assessment of the aqueous inflow by 7.0 T MRI. Under anesthetic condition in vivo, the mean anterior chamber volume (ACV) in rats was 8493.6 ± 657.4 μm 3 , no differences were observed in the aqueous inflow measured by topical instillation of 234.5 mg/ml Gd-DTPA in 0.2% azone (0.182 ± 0.011 μl/min) between that measured by anterior chamber injection (0.165 ± 0.041 μl/min, P > 0.05), Timolol reduced aqueous inflow to 0.124 ± 0.020 μl/min (P < 0.05). Our results indicated that Gd-enhanced 7.0 T MRI allows evaluation of the Gd signal variation and anterior chamber volume in rats in vivo. The aqueous inflow calculation via non-invasive local application of 234.5 mg/ml Gd-DTPA can be assessed by the variability of relative concentration of Gd-DTPA in anterior chamber and ACV in vivo, under anesthetic condition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Age, Gender, Biometry, Refractive Error, and the Anterior Chamber Angle among Alaskan Eskimos

PubMed Central

Wojciechowski, Robert; Congdon, Nathan; Anninger, William; Broman, Aimee Teo

2011-01-01

Background The prevalence of angle-closure glaucoma (ACG) is greater for Eskimos/Inuit than it is for any other ethnic group in the world. Although it has been suggested that this prevalence may be due to a population tendency toward shallower anterior chamber angles, available evidence for other populations such as Chinese with high rates of ACG has not consistently demonstrated such a tendency. Methods A reticule, slit-lamp, and standard Goldmann one-mirror goniolens were used to make measurements in the anterior chamber (AC) angle according to a previously reported protocol for biometric gonioscopy (BG) (Ophthalmology 1999;106:2161–7). Measurements were made in all four quadrants of one eye among 133 phakic Alaskan Eskimos aged 40 years and older. Automatic refraction, dilated examination of the anterior segment and optic nerve, and A-scan measurements of AC depth, lens thickness, and axial length were also carried out for all subjects. Results Both central and peripheral AC measurements for the Eskimo subjects were significantly lower than those previously reported by us for Chinese, blacks, and whites under the identical protocol. Eskimos also seemed to have somewhat more hyperopia. There were no differences in biometric measurements between men and women in this Eskimo population. Angle measurements by BG seemed to decline more rapidly over life among Eskimos and Chinese than blacks or whites. Although there was a significant apparent decrease in AC depth, increase in lens thickness, and increase in hyperopia with age among Eskimos, all of these trends seemed to reverse in the seventh decade and beyond. Conclusions Eskimos do seem to have shallower ACs than do other racial groups. Measurements of the AC angle seem to decline more rapidly over life among Eskimos than among blacks or whites, a phenomenon also observed by us among Chinese, another group with high ACG prevalence. This apparent more rapid decline may be due to a cohort effect with higher prevalence of myopia and resulting wider angles among younger Eskimos and Chinese. PMID:12578783

Phakic iris-fixated intraocular lens placement in the anterior chamber: effects on aqueous flow.

PubMed

Repetto, Rodolfo; Pralits, Jan O; Siggers, Jennifer H; Soleri, Paolo

2015-05-01

Phakic intraocular lenses (pIOLs) are used for correcting vision; in this paper we investigate the fluid dynamical effects of an iris-fixated lens in the anterior chamber. In particular, we focus on changes in the wall shear stress (WSS) on the cornea and iris, which could be responsible for endothelial and pigment cell loss, respectively, and also on the possible increase of the intraocular pressure, which is known to correlate with the incidence of secondary glaucoma. We use a mathematical model to study fluid flow in the anterior chamber in the presence of a pIOL. The governing equations are solved numerically using the open source software OpenFOAM. We use an idealized standard geometry for the anterior chamber and a realistic geometric description of the pIOL. We consider separately the main mechanisms that produce fluid flow in the anterior chamber. The numerical simulations allow us to obtain a detailed description of the velocity and pressure distribution in the anterior chamber, and indicated that implantation of the pIOL significantly modifies the fluid dynamics in the anterior chamber. However, lens implantation has negligible influence on the intraocular pressure and does not produce a significant increase of the shear stress on the cornea, while the shear stress on the iris, although increased, is not enough to cause detachment of cells. We conclude that alterations in the fluid dynamics in the anterior chamber as a result of lens implantation are unlikely to be the cause of medical complications associated with its use.

Cling film as a barrier against CJD in corneal contact A-scan ultrasonography.

PubMed

Rani, Asha; Dunne, Mark C M; Barnes, Derek A

2003-01-01

To determine the validity of covering a corneal contact transducer probe with cling film as protection against the transmission of Creutzfeldt-Jakob disease (CJD). The anterior chamber depth, lens thickness and vitreous chamber depth of the right eyes of 10 subjects was recorded, under cycloplegia, with and without cling film covering over the transducer probe of a Storz Omega Compu-scan Biometric Ruler. Measurements were repeated on two occasions. Cling film covering did not influence bias or repeatability. Although the 95% limits of agreement between measurements made with and without cling film covering tended to exceed the intrasessional repeatability, they did not exceed the intersessional repeatability of measurements taken without cling film. The results support the use of cling film as a disposable covering for corneal contact A-scan ultrasonography to avoid the risk of spreading CJD from one subject to another.

Volume-based characterization of postocclusion surge.

PubMed

Zacharias, Jaime; Zacharias, Sergio

2005-10-01

To propose an alternative method to characterize postocclusion surge using a collapsible artificial anterior chamber to replace the currently used rigid anterior chamber model. Fundación Oftamológica Los Andes, Santiago, Chile. The distal end of a phacoemulsification handpiece was placed inside a compliant artificial anterior chamber. Digital recordings of chamber pressure, chamber volume, inflow, and outflow were performed during occlusion break of the phacoemulsification tip. The occlusion break profile of 2 different consoles was compared. Occlusion break while using a rigid anterior chamber model produced a simultaneous increase of chamber inflow and outflow. In the rigid chamber model, pressure decreased sharply, reaching negative pressure values. Alternatively, with the collapsible chamber model, a delay was observed in the inflow that occurs to compensate the outflow surge. Also, the chamber pressure drop was smaller in magnitude, never undershooting below atmospheric pressure into negative values. Using 500 mm Hg as vacuum limit, the Infiniti System (Alcon) performed better that the Legacy (Alcon), showing an 18% reduction in peak volume variation. The collapsible anterior chamber model provides a more realistic representation of the postocclusion surge events that occur in the real eye during cataract surgery. Peak volume fluctuation (mL), half volume recovery time(s), and volume fluctuation integral value (mL x s) are proposed as realistic indicators to characterize the postocclusion surge performance. These indicators show that the Infiniti System has a better postocclusion surge behavior than the Legacy System.

Changes in ocular biometry and anterior chamber parameters after pharmacologic mydriasis and peripheral iridotomy in primary angle closure suspects.

PubMed

Razeghinejad, Mohammad Reza; Lashkarizadeh, Hamid; Nowroozzadeh, Mohammad Hossein; Yazdanmehr, Mohammad

2016-01-01

The aim of this study was to evaluate the effects of pharmacologic mydriasis and Peripheral Iridotomy (PI) on ocular biometry and anterior chamber parameters in primary angle closure suspects. In this prospective interventional case series, 21 primary angle closure suspects were enrolled. Intraocular pressure, refraction, ocular biometry (Lenstar, LS900), and anterior chamber parameters (Pentacam HR) were measured at four occasions: before PI (before and after mydriasis with phenylephrine) and two weeks after PI (before and after mydriasis). The study was conducted on both eyes and only one eye per patient, in random, was included in the analysis. The mean age of the participants was 60±7 years and 17 (81%) were female. There were no significant differences in intraocular pressure, refraction, keratometry, biometric and anterior chamber parameters between groups, except for anterior chamber volume, which showed increments with PI and mydriasis. The corresponding values for anterior chamber volume were as follows: 88.2±13.7mm(3) before PI, undilated; 106.3±18.8 before PI, dilated; 99.0±14.6 after PI, undilated, and 107.4±16.5 after PI, dilated (P<0.001). This study showed no change in the ocular biometric and anterior chamber parameters including iridocorneal angle after PI and/or pharmacologic mydriasis except for increments in anterior chamber volume. This factor has the potential to be used as a numerical proxy for iris position in evaluating and monitoring patients with primary angle closure suspects after PI. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Determinants and two-year change in anterior chamber angle width in a Chinese population.

PubMed

Congdon, Nathan G; Kong, Xiangbin; Meltzer, Mirjam E; Chen, Qianyun; Zeng, Yangfa; Huang, Yuanzhou; Zhang, Jian; He, Mingguang

2012-12-01

To study the population distribution and longitudinal changes in anterior chamber angle width and its determinants among Chinese adults. Prospective cohort, population-based study. Persons aged 35 years or more residing in Guangzhou, China, who had not previously undergone incisional or laser eye surgery. In December 2008 and December 2010, all subjects underwent automated keratometry, and a random 50% sample had anterior segment optical coherence tomography with measurement of angle-opening distance at 500 μm (AOD500), angle recess area (ARA), iris thickness at 750 μm (IT750), iris curvature, pupil diameter, corneal thickness, anterior chamber width (ACW), lens vault (LV), and lens thickness (LT) and measurement of axial length (AL) and anterior chamber depth (ACD) by partial coherence laser interferometry. Baseline and 2-year change in AOD500 and ARA in the right eye. A total of 745 subjects were present for full biometric testing in both 2008 and 2010 (mean age at baseline, 52.2 years; standard deviation [SD], 11.5 years; 53.7% were female). Test completion rates in 2010 varied from 77.3% (AOD500: 576/745) to 100% (AL). Mean AOD500 decreased from 0.25 mm (SD, 0.13 mm) in 2008 to 0.21 mm (SD, 13 mm) in 2010 (difference, -0.04; 95% confidence interval [CI], -0.05 to -0.03). The ARA decreased from 21.5 ± 3.73 10(-2) mm(2) to 21.0 ± 3.64 10(-2) mm(2) (difference, -0.46; 95% CI, -0.52 to -0.41). The decrease in both was most pronounced among younger subjects and those with baseline AOD500 in the widest quartile at baseline. The following baseline variables were significantly associated with a greater 2-year decrease in both AOD500 and ARA: deeper ACD, steeper iris curvature, smaller LV, greater ARA, and greater AOD500. By using simple regression models, we could explain 52% to 58% and 93% of variation in baseline AOD500 and ARA, respectively, but only 27% and 16% of variation in 2-year change in AOD500 and ARA, respectively. Younger persons and those with the least crowded anterior chambers at baseline have the largest 2-year decreases in AOD500 and ARA. The ability to predict change in angle width based on demographic and biometric factors is relatively poor, which may have implications for screening. The author(s) have no proprietary or commercial interest in any materials discussed in this article. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Automatic anterior chamber angle assessment for HD-OCT images.

PubMed

Tian, Jing; Marziliano, Pina; Baskaran, Mani; Wong, Hong-Tym; Aung, Tin

2011-11-01

Angle-closure glaucoma is a major blinding eye disease and could be detected by measuring the anterior chamber angle in the human eyes. High-definition OCT (Cirrus HD-OCT) is an emerging noninvasive, high-speed, and high-resolution imaging modality for the anterior segment of the eye. Here, we propose a novel algorithm which automatically detects a new landmark, Schwalbe's line, and measures the anterior chamber angle in the HD-OCT images. The distortion caused by refraction is corrected by dewarping the HD-OCT images, and three biometric measurements are defined to quantitatively assess the anterior chamber angle. The proposed algorithm was tested on 40 HD-OCT images of the eye and provided accurate measurements in about 1 second.

Temperature in the anterior chamber during phacoemulsification.

PubMed

Suzuki, Hisaharu; Oki, Kotaro; Igarashi, Tsutomu; Shiwa, Toshihiko; Takahashi, Hiroshi

2014-05-01

To evaluate changes in the aqueous humor temperature using 2 phacoemulsification units (Stellaris 28.5 kHz device and Whitestar Signature 40 kHz device). Nippon Medical School, Musashikosugi Hospital, Kawasaki City, Kanagawa, Japan. Experimental study. Aqueous humor temperatures were measured with a temperature probe set in the anterior chamber during ultrasound (US) oscillation in porcine eyes under 5 conditions. Continuous longitudinal oscillation caused a rapid rise in aqueous humor temperature, while the pulse and elliptical modes suppressed temperature elevation. Reducing the number of US tip vibrations did not reduce the temperature in the anterior chamber. However, raising the vacuum setting allowed the aspirations to rise to the set value, thereby lowering the temperature in the anterior chamber. Because differences in the phacoemulsification settings can lead to temperature elevations in the anterior chamber, surgeons must carefully monitor these settings to prevent corneal tissue damage. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Association of biometric factors with anterior chamber angle widening and intraocular pressure reduction after uneventful phacoemulsification for cataract.

PubMed

Huang, Guofu; Gonzalez, Eduardo; Lee, Roland; Chen, Yi-Chun; He, Mingguang; Lin, Shan C

2012-01-01

To evaluate anterior chamber biometric factors associated with the degree of angle widening and intraocular pressure (IOP) reduction after phacoemulsification. University of California, San Francisco, California, USA. Case series. Anterior chamber parameters obtained by anterior segment coherence tomography were compared preoperatively and 3 months postoperatively. Measurements included the angle opening distance 500 μm anterior to the scleral spur (AOD500), trabecular-iris space area 500 μm from the scleral spur (TISA500), iris curvature (I-Curv), anterior chamber angle (ACA), trabecular-iris space area, anterior chamber volume, anterior chamber width, and lens vault (LV). The study enrolled 73 eyes. The mean patient age was 77.45 years ± 7.84 (SD); 65.75% of patients were women. From preoperatively to 3 months postoperatively, the mean AOD500 increased significantly (0.254 ± 0.105 to 0.433 ± 0.108 mm) and the mean IOP decreased significantly (14.97 ± 3.35 to 12.62 ± 3.37 mm Hg) (P<.001). The reduction in IOP was correlated with the increase in AOD500 (r = 0.240, P=.041) and preoperative LV (r = 0.235, P=.045). After adjusting for related factors, AOD500 widening was positively correlated with LV (β = 0.458, P=.044) and I-Curv (β = 0.235, P=.043) and negatively correlated with preoperative TISA500 (β = -0.269, P=.025) and ACA (β = -0.919, P=.027). Surgically induced AOD widening was significantly correlated with anterior chamber biometric factors. Preoperative LV appears to be a significant factor in angle widening and IOP reduction after phacoemulsification. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

The effect of pharmacologic pupillary dilatation on anterior segment parameters in patients with exfoliation syndrome.

PubMed

Mocan, Mehmet Cem; Ustunel, Saim; Dikmetas, Ozlem; Bozkurt, Banu; Irkec, Murat

2014-01-01

The purpose of this study was to evaluate the effect of pharmacologic pupillary dilatation on anterior chamber depth (ACD) and anterior chamber angle (ACA) in eyes with exfoliation syndrome (XFS). Thirty-six eyes of 36 patients with XFS were evaluated with slit-lamp examination, Goldmann applanation tonometry and ultrasound biomicroscopy (UBM) under standard light conditions. Primary outcome parameters were defined as the change in ACD and ACA measured before and 40 min after instillation of a single drop of either 1% cyclopentolate (Group I; n=12), 2.5% phenylephrine (Group II; n=12) or 1% tropicamide (Group III; n=12). Change in intraocular pressure (IOP) during the same time interval was included as a secondary outcome measure. The average predilatation ACD, ACA and IOP values in the study subjects were 2.54±0.40 mm, 27.9±6.3° and 14.9±3.1 mmHg, respectively. There were no significant differences in the mean age (p=0.461), the female/male ratio (p=0.232), baseline ACD (p=0.841), ACA (p=0.761) or IOP (p=0.070) within the three groups. Differences in dilation induced changes in ACD (p=0.108), ACA (p=0.636) and IOP (p=0.160) between the three groups were not statistically significant. Pupillary dilatation with a single drop of 1.0% cyclopentolate, 2.5% phenylephrine or 1% tropicamide is not associated with shallowing of the anterior chamber or narrowing of the ACA in patients with XFS who present with open angles. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

[Changes of structures of anterior chamber angle in rabbit chronic high intraocular pressure model].

PubMed

Lei, Xun-wen; Wei, Ping; Li, Xiao-lin; Yang, Kan; Lei, Jian-zhen

2009-10-01

To observe the anterior chamber angle changes occurred in compound Carbomer-induced chronic high intraocular pressure (IOP) model in rabbit eyes. It was an experimental study. Thirty two rabbits were randomly divided into eight groups. Compound Carbomer (0.3%, 0.3 ml) was injected into the left anterior chamber. A group of rabbits were randomly killed after 1, 2, 3, 4, 6, 8, 10 and 12 weeks. The anterior chamber of the rabbit eye specimens was observed. IOP increased slowly following the application of the drug, high IOP lasted for 3 months. The drug-induced changes of anterior chamber angle consisted of early inflammatory response and late fibrous changes. Inflammatory response occurred in early stage and reduced or disappeared after 3 weeks. Fibrous degeneration and adhesion obstruction occurred in the anterior chamber angle after 4 weeks. Under the electron microscope, the trabecular was expanded and deformed, with hyperplasia of collagen and elastic fibers. Endothelial cells were separated from the trabecular, and showed the morphology of lymphocytes, with the function similar to the macrophages. Phagocytized Carbomer particles were transported through the vacuoles of Schlemm's canal endothelial cells. Large vacuoles gradually reduced. Excessive Carbomer particles were accumulated in the endothelial cells and obstructed the Schlemm's canal. This induced the fibrous proliferation and the destruction of anterior chamber angle structures. The obstruction of aqueous humor outflow induced by compound Carbomer in rabbit high IOP model is caused mainly by the changes in trabecular endothelial cells.

[Chamber Angle Assessment in Clinical Practice - A Comparison between Optical Coherence Tomography and Gonioscopy].

PubMed

Mösler, M P; Werner, J U; Lang, G K

2015-07-01

In glaucoma the structures of the anterior chamber are important for classification, therapy, progression and prognosis. In this context anterior segment optical coherence tomography (AS-OCT) gains more relevance. This study compares AS-OCT with gonioscopy in diagnostic performance of chamber angle (CA) assessment. 104 consecutive subjects with glaucoma underwent AS-OCT imaging using the Visante OCT. RESULTS were compared to gonioscopic grading from patient history using the Shaffer system. In addition, anterior chamber depth (ACD) assessment using slitlamp examination was evaluated as a prognostic factor for chamber angle width (CAW) and verified by AS-OCT measurement. Average CAW was 29° (AS-OCT). 17 % of the CAs that were "wide" in gonioscopy (variance 5-55°), showed a "narrow" CA in AS-OCT. 35 % of the CAs that were "narrow" in gonioscopy (variance 0-39°) showed a "wide" CA in AS-OCT. ACD assessment using slitlamp examination is a good predictor for CAW. In this context the technique provides equal informative value as gonioscopy. In cases of "wide" ACDs it is even superior. The critical ACD for an increased risk of angle closure is 2.4 mm. Concerning the critical ACD (< 2.4 mm) the technique gave the possibility to estimate, whether the patients were in the crucial range or not. Average ACD was 2.7 mm (AS-OCT). A strong correlation (correlation coefficient 0.83) between ACD and CAW was observed. Variation of 1 mm in the ACD leads to a change of 18.9° in the CAW. All patients with angle closure glaucoma were below this threshold and 74 % of patients with critical ACD had "narrow" (AS-OCT) CAs. In the case of routine clinical practice with inexperienced residents or circumstances that make gonioscopy difficult or impossible, optical coherence tomography is an effective alternative to the gold standard and is to some extent even superior. Georg Thieme Verlag KG Stuttgart · New York.

Management of bipseudophakia with implantation of an iris claw lens.

PubMed

Izak, Milan G J; Werner, Liliana; Izak, Andrea M; Apple, David J

2003-07-01

We discuss a case of bipseudophakia with secondary dislocation of a posterior chamber intraocular lens (IOL) into the anterior chamber that was managed by explantation of the anterior and posterior chamber IOLs and implantation of an iris claw IOL.

Effect of Ramadan fasting in tropical summer months on ocular refractive and biometric characteristics.

PubMed

Nowroozzadeh, Mohammad Hosein; Mirhosseini, Amirhossein; Meshkibaf, Mohammad Hassan; Roshannejad, Javad

2012-03-01

Islamic Ramadan is the month of fasting, in which intake of food and drink is restricted from sunrise until sunset. The objective of the present study was to find out the effect of altered eating habits during Ramadan fasting on ocular refractive and biometric properties. In this prospective case series, 40 eyes of 22 healthy volunteers with a mean age of 60.55 ± 12.20 years were enrolled. Patients with any systemic disorder and eyes with pathology or previous surgery were excluded. One month before Ramadan (at 8.00 am), during Ramadan fasting (at 8.00 am and 4.00 pm) and one month later during the non-fasting period (at 8.00 am), ocular refractive and biometric characteristics were measured using an autokeratorefractometer (Auto-Kerato-Refractometer KR-8900; Topcon Co, Tokyo, Japan) and contact ultrasonic biometry (Nidek Echoscan US 800; Nidek Co, Tokyo, Japan). Anterior chamber depth was significantly increased during fasting compared with baseline measurements and returned to baseline one month after Ramadan (3.22 ± 0.07 mm and 4.33 ± 0.17 mm for non-fasting and fasting, respectively; p < 0.001). The anterior chamber depth measurements were significantly larger at 8.00 am during fasting compared with 4.00 pm (p = 0.01). Axial length was significantly decreased during fasting and returned to baseline one month after Ramadan (23.09 ± 0.14 mm and 22.65 ± 0.18 mm, for non-fasting and fasting, respectively; p < 0.001). Intraocular lens power calculations were significantly increased during fasting and returned to baseline one month after Ramadan (SRK-T formula: 21.46 ± 0.27 D and 22.92 ± 0.46 D, for non-fasting and fasting, respectively; p < 0.001). There were no significant differences in spherical equivalent, corneal astigmatism, mean keratometry and flatter and steeper corneal radii of curvature between time intervals. Ramadan fasting is associated with statistically significant alterations in anterior chamber depth and axial length that result in both statistically and clinically significant changes in intraocular lens power calculations. Therefore, relying on measurements taken during this month might lead to refractive errors after cataract surgery. © 2012 The Authors. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

Correlation between anterior chamber characteristics and laser flare photometry immediately after femtosecond laser treatment before phacoemulsification

PubMed Central

Pahlitzsch, M; Torun, N; Pahlitzsch, M L; Klamann, M K J; Gonnermann, J; Bertelmann, E; Pahlitzsch, T

2016-01-01

Purpose To assess the anterior chamber (AC) characteristics and its correlation to laser flare photometry immediately after femtosecond laser-assisted capsulotomy and photodisruption. Patients and methods The study included 97 cataract eyes (n=97, mean age 68.6 years) undergoing femtosecond laser-assisted cataract surgery (FLACS). Three cohorts were analysed relating to the flare photometry directly post femtosecond laser treatment (flare <100 n=28, 69.6±7 years; flare 100–249 n=47, 67.7±8 years; flare >249 photon counts per ms cohort n=22, 68.5±10 years). Flare photometry (KOWA FM-700), corneal topography (Oculus Pentacam, Germany: AC depth, volume, angle, pachymetry), axial length, pupil diameter, and endothelial cells were assessed before FLACS, immediately after femtosecond laser treatment and 1 day postoperative (LenSx Alcon, USA). Statistical data were analysed by SPSS v19.0, Inc. Results The AC depth, AC volume, AC angle, central and thinnest corneal thickness showed a significant difference between flare <100 vs flare 100–249 10 min post femtosecond laser procedure (P=0.002, P=0.023, P=0.007, P=0.003, P=0.011, respectively). The AC depth, AC volume, and AC angle were significantly larger (P=0.001, P=0.007, P=0.003, respectively) in the flare <100 vs flare >249 cohort 10 min post femtosecond laser treatment. Conclusions A flat AC, low AC volume, and a narrow AC angle were parameters associated with higher intraocular inflammation. These criteria could be used for patient selection in FLACS to reduce postoperative intraocular inflammation. PMID:27229702

Correlation between anterior chamber characteristics and laser flare photometry immediately after femtosecond laser treatment before phacoemulsification.

PubMed

Pahlitzsch, M; Torun, N; Pahlitzsch, M L; Klamann, M K J; Gonnermann, J; Bertelmann, E; Pahlitzsch, T

2016-08-01

PurposeTo assess the anterior chamber (AC) characteristics and its correlation to laser flare photometry immediately after femtosecond laser-assisted capsulotomy and photodisruption.Patients and methodsThe study included 97 cataract eyes (n=97, mean age 68.6 years) undergoing femtosecond laser-assisted cataract surgery (FLACS). Three cohorts were analysed relating to the flare photometry directly post femtosecond laser treatment (flare <100 n=28, 69.6±7 years; flare 100-249 n=47, 67.7±8 years; flare >249 photon counts per ms cohort n=22, 68.5±10 years). Flare photometry (KOWA FM-700), corneal topography (Oculus Pentacam, Germany: AC depth, volume, angle, pachymetry), axial length, pupil diameter, and endothelial cells were assessed before FLACS, immediately after femtosecond laser treatment and 1 day postoperative (LenSx Alcon, USA). Statistical data were analysed by SPSS v19.0, Inc.ResultsThe AC depth, AC volume, AC angle, central and thinnest corneal thickness showed a significant difference between flare <100 vs flare 100-249 10 min post femtosecond laser procedure (P=0.002, P=0.023, P=0.007, P=0.003, P=0.011, respectively). The AC depth, AC volume, and AC angle were significantly larger (P=0.001, P=0.007, P=0.003, respectively) in the flare <100 vs flare >249 cohort 10 min post femtosecond laser treatment.ConclusionsA flat AC, low AC volume, and a narrow AC angle were parameters associated with higher intraocular inflammation. These criteria could be used for patient selection in FLACS to reduce postoperative intraocular inflammation.

Evaluation of the anterior chamber angle in glaucoma: a report by the american academy of ophthalmology.

PubMed

Smith, Scott D; Singh, Kuldev; Lin, Shan C; Chen, Philip P; Chen, Teresa C; Francis, Brian A; Jampel, Henry D

2013-10-01

To assess the published literature pertaining to the association between anterior segment imaging and gonioscopy and to determine whether such imaging aids in the diagnosis of primary angle closure (PAC). Literature searches of the PubMed and Cochrane Library databases were last conducted on July 6, 2011. The searches yielded 371 unique citations. Members of the Ophthalmic Technology Assessment Committee Glaucoma Panel reviewed the titles and abstracts of these articles and selected 134 of possible clinical significance for further review. The panel reviewed the full text of these articles and identified 79 studies meeting the inclusion criteria, for which the panel methodologist assigned a level of evidence based on a standardized grading scheme adopted by the American Academy of Ophthalmology. Three, 70, and 6 studies were rated as providing level I, II, and III evidence, respectively. Quantitative and qualitative parameters defined from ultrasound biomicroscopy (UBM), anterior segment optical coherence tomography (OCT), Scheimpflug photography, and the scanning peripheral anterior chamber depth analyzer (SPAC) demonstrate a strong association with the results of gonioscopy. There is substantial variability in the type of information obtained from each imaging method. Imaging of structures posterior to the iris is possible only with UBM. Direct imaging of the anterior chamber angle (ACA) is possible using UBM and OCT. The ability to acquire OCT images in a completely dark environment allows greater sensitivity in detecting eyes with appositional angle closure. Noncontact imaging using OCT, Scheimpflug photography, or SPAC makes these methods more attractive for large-scale PAC screening than contact imaging using UBM. Although there is evidence suggesting that anterior segment imaging provides useful information in the evaluation of PAC, none of these imaging methods provides sufficient information about the ACA anatomy to be considered a substitute for gonioscopy. Longitudinal studies are needed to validate the diagnostic significance of the parameters measured by these instruments for prospectively identifying individuals at risk for PAC. Proprietary or commercial disclosure may be found after the references. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Partitioning an Artificial Anterior Chamber With a Latex Diaphragm to Simulate Anterior and Posterior Segment Pressure Dynamics: The "DMEK Practice Stage," Where Surgeons Can Rehearse the "DMEK Dance".

PubMed

Sáles, Christopher S; Straiko, Michael D; Fernandez, Ana Alzaga; Odell, Kelly; Dye, Philip K; Tran, Khoa D

2018-02-01

To present a novel apparatus for simulating the anterior and posterior segment pressure dynamics involved in executing Descemet membrane endothelial keratoplasty (DMEK) surgery when using a chamber-shallowing technique. An artificial anterior chamber (AAC), 18-mm trephine, latex glove, two 3-mL syringes, and one donor cornea comprising an intact corneoscleral cap from which a DMEK tissue was peeled and punched are required for the model. After making the corneal incisions with the corneoscleral cap mounted on the AAC in the usual fashion, the corneoscleral cap is remounted onto the dried AAC over an 18-mm latex diaphragm. The space between the latex diaphragm and the cornea is filled with saline to pressurize the anterior chamber, and the posterior segment is pressurized with air from a syringe. The resulting apparatus comprises a posterior segment and anterior chamber that exert pressure on each other by way of a distensible latex diaphragm. A novice and experienced DMEK surgeon and 2 eye bank technicians were able to assemble the apparatus and perform the routine steps of a DMEK procedure, including maneuvers that require shallowing the anterior chamber and lowering its pressure. Only one cornea was required per apparatus. We present a novel in vitro model of the human eye that more closely mimics the anterior and posterior segment pressure dynamics of in vivo DMEK surgery than average human and animal cadaveric globes. The model is easy to assemble, inexpensive, and applicable to a range of teaching environments.

Clear-cornea cataract surgery: pupil size and shape changes, along with anterior chamber volume and depth changes. A Scheimpflug imaging study.

PubMed

Kanellopoulos, Anastasios John; Asimellis, George

2014-01-01

To investigate, by high-precision digital analysis of data provided by Scheimpflug imaging, changes in pupil size and shape and anterior chamber (AC) parameters following cataract surgery. The study group (86 eyes, patient age 70.58±10.33 years) was subjected to cataract removal surgery with in-the-bag intraocular lens implantation (pseudophakic). A control group of 75 healthy eyes (patient age 51.14±16.27 years) was employed for comparison. Scheimpflug imaging (preoperatively and 3 months postoperatively) was employed to investigate central corneal thickness, AC depth, and AC volume. In addition, by digitally analyzing the black-and-white dotted line pupil edge marking in the Scheimpflug "large maps," the horizontal and vertical pupil diameters were individually measured and the pupil eccentricity was calculated. The correlations between AC depth and pupil shape parameters versus patient age, as well as the postoperative AC and pupil size and shape changes, were investigated. Compared to preoperative measurements, AC depth and AC volume of the pseudophakic eyes increased by 0.99±0.46 mm (39%; P<0.001) and 43.57±24.59 mm(3) (36%; P<0.001), respectively. Pupil size analysis showed that the horizontal pupil diameter was reduced by -0.27±0.22 mm (-9.7%; P=0.001) and the vertical pupil diameter was reduced by -0.32±0.24 mm (-11%; P<0.001). Pupil eccentricity was reduced by -39.56%; P<0.001. Cataract extraction surgery appears to affect pupil size and shape, possibly in correlation to AC depth increase. This novel investigation based on digital analysis of Scheimpflug imaging data suggests that the cataract postoperative photopic pupil is reduced and more circular. These changes appear to be more significant with increasing patient age.

Application of 5-Fluorouracil-Polycaprolactone Sustained-Release Film in Ahmed Glaucoma Valve Implantation Inhibits Postoperative Bleb Scarring in Rabbit Eyes.

PubMed

Bi, Xiu-Zeng; Pan, Wei-Hua; Yu, Xin-Ping; Song, Zong-Ming; Ren, Zeng-Jin; Sun, Min; Li, Cong-Hui; Nan, Kai-Hui

2015-01-01

This study was designed to investigate whether 5-fluorouracil (5-Fu)-polycaprolactone sustained-release film in Ahmed glaucoma valve implantation inhibits postoperative bleb scarring in rabbit eyes. Eighteen New Zealand white rabbits were randomly divided into three groups (A, B and C; n = 6 per group). Group A received combined 5-Fu-polycaprolactone sustained-release film application and Ahmed glaucoma valve implantation, group B received local infiltration of 5-Fu and Ahmed glaucoma valve implantation, and group C received Ahmed glaucoma valve implantation. Postoperative observations were made of the anterior segment, intraocular pressure, central anterior chamber depth, blebs, drainage tube, and accompanying ciliary body detachment. The pathology of the blebs and surrounding tissues were observed at month 3 postoperatively. We revealed that the 5-Fu-polycaprolactone sustained-release film maintained a release concentration range of 13.7 ± 0.12 to 37.41 ± 0.47 μg/ml over three months in vitro. Postoperatively, diffuse blebs with ridges were found in all eyes in group A, two blebs were observed in group B, and no bleb formation was present in group C. The postoperative central anterior chamber depth in group A was significantly less than that of the other two groups. The postoperative intraocular pressure of group A stabilized at 6.33-8.67 mmHg, whereas that of group C gradually remained at 7.55-10.02 mmHg. The histopathology showed that the fibrous tissue thickness of the blebs in group A was significantly thinner than that of the other groups. We conclude that the 5-Fu-polycaprolactone sustained-release film had a sustained drug release effect, which promoted the inhibition of bleb scarring after Ahmed glaucoma valve implantation.

Clinical Efficacy of Ciliary Ring Incision Combined with Modified Partial Pars Plana Vitrectomy for Malignant Glaucoma.

PubMed

Yu, Jianchun; Chen, Xing; Zhou, Danying; Shen, Jian; Wu, Yanbing; Sun, Qingzhu

2018-06-10

BACKGROUND Currently, safe and effective surgical treatment of malignant glaucoma is still under investigation. This study evaluated the clinical efficacy of ciliary ring incision combined with modified partial pars plana vitrectomy in the treatment of malignant glaucoma. The technique is particularly useful in the treatment of "phakic" patients with malignant glaucoma, especially those who wish to preserve the natural lens. MATERIAL AND METHODS We retrospectively analyzed 13 cases (16 eyes) of malignant glaucoma in which patients underwent ciliary ring incision combined with modified partial pars plana vitrectomy based on follow-up data collected from May 2004 to March 2017. The data we analyzed included postoperative best-corrected visual acuity(BCVA), intraocular pressure (IOP), anterior chamber depth (ACD), optic cup changes, and surgical complications; some patients underwent visual field tracking. The mean follow-up period was 33.1±10.6 (range, 19-46) months. RESULTS A statistically significant number of eyes had improved visual acuity 1 year after surgery compared with the preoperative difference (Z=-3.853, P=0.000). Increases in the mean anterior chamber depth and decreases in the mean IOP measured at the 1-week and the 1-year follow-ups were also statistically significant. There were no serious complications during the follow-up period. CONCLUSIONS Ciliary ring incision combined with modified partial pars plana vitrectomy for malignant glaucoma not only provided a clear and reliable intraoperative vitrectomy channel, but it also caused less disturbance of intraocular tissue structure and fewer complications. It also has the advantage of preserving the lens and avoiding further damage to the anatomy in the anterior segment of the eye.

Effect of Fasting on Corneal Biomechanical and Structural Parameters.

PubMed

Sarici, Ahmet M; Yuksel Elgin, Cansu; Dikkaya, Funda

2016-07-01

To evaluate the effects of hunger and thirst on corneal biomechanical and structural parameters during Ramadan fasting. Corneal biomechanical properties and intraocular pressures of 29 eyes of 29 healthy subjects were evaluated by Reichert ocular response analyzer; and structural and anatomical properties of cornea and anterior eye chamber of same eyes were scanned with Oculus Pentacam anterior segment analyzer. Each eye has been evaluated at 8 am and 4 pm both during and 1 month after Ramadan. Changes of subjects' weight were calculated and their relationship with corneal biomechanical and structural parameters was assessed. Intraday changes in horizontal corneal astigmatism (p = 0.02), anterior chamber volume (p = 0.01), intraocular pressure associated with the Goldmann IOPg (p = 0.02) and corneal resistance factor (CRF) (p = 0.04) were significantly different when measured during the fasting period in Ramadan and 1 month thereafter. Moreover, when we compared 8 am measurements taken during and after Ramadan, we observed significant differences for anterior chamber volume (p = 0.04) and anterior chamber angle values (p = 0.03). Similarly, for 4 pm measurements, there were significant differences for IOPg (p = 0.01) and CRF values (p = 0.00). Fasting lasting for more than 12 h during Ramadan creates an important window of opportunity to investigate the response of anterior chamber of eye to hunger and thirst. The current study contributes to the existing literature on the effects of dietary habits and water intake on corneal and anterior chamber properties.

Viscoelastic Tamponade Applied to the Ocular Surface for Enhanced Control of Gaseous Egress From the Anterior Chamber During Final Bubble Titration in DMEK Surgery: The "Polite" Burp.

PubMed

Sales, Christopher S; Fernandez, Ana Alzaga; Anwar, Zane

2018-07-01

To present a novel technique for enhancing the surgeon's control over the volume of air or gas that is "burped" from the anterior chamber during final bubble and intraocular pressure (IOP) titration in Descemet membrane endothelial keratoplasty. After ascertaining that the intracameral bubble is either too large and/or has rendered IOP too high, a bead of ophthalmic viscoelastic is applied to the ocular surface over a paracentesis incision, which is then depressed in the usual fashion to burp gas from the anterior chamber. The weight and viscosity of the viscoelastic create a tamponade that slows the egress of gas from the anterior chamber, thereby making it more controllable. If the bubble size or IOP needs to be reduced at the conclusion of the Descemet membrane endothelial keratoplasty procedure, application of ophthalmic viscoelastic over the paracentesis can enhance the surgeon's control over the volume of gas burped from the anterior chamber, thereby reducing the tendency to swing between a bubble that is too large or too small.

An evaluation of the effects of eyeball structure on ocular pulse amplitude in healthy subjects.

PubMed

Ishii, Kotaro; Mori, Mikiro; Oshika, Tetsuro

2012-12-01

To evaluate the effects of eyeball structure on ocular pulse amplitude (OPA) measured using dynamic contour tonometer (DCT). In 86 eyes of 43 healthy subjects, we measured OPA and intraocular pressure (IOP) with DCT (DCT-IOP), IOP with Goldmann applanation tonometry (GAT-IOP), central corneal thickness (CCT), corneal thickness 2 mm (2 mmCT) and 4 mm (4 mmCT) apart from the center, corneal volume within a 3.5-mm radius from the corneal center, corneal curvature, anterior chamber depth, anterior chamber volume, and axial length (AL). OPA had a significant positive correlation with GAT-IOP (Pearson's r = 0.412, p < 0.001), DCT-IOP (r = 0.350, p < 0.001), and 4 mmCT (r = 0.244, p = 0.0231), and had a significant negative correlation with AL (r = -0.268, p = 0.0122). In a multiple linear regression analysis, AL and GAT-IOP were significantly associated with OPA. OPA measured with DCT is significantly influenced by several factors, such as IOP, peripheral corneal thickness (4 mmCT), and AL.

Age-related changes in optical and biometric characteristics of emmetropic eyes.

PubMed

Atchison, David A; Markwell, Emma L; Kasthurirangan, Sanjeev; Pope, James M; Smith, George; Swann, Peter G

2008-04-28

We measured optical and biometric parameters of emmetropic eyes as a function of age. There were approximately 20 subjects each in age groups 18-29, 30-39, 40-49, 50-59, and 60-69 years with similar male and female numbers. One eye was tested for each subject, having spherical equivalent in the range -0.88 D to +0.75 D and

A proposed simple method for measurement in the anterior chamber angle: biometric gonioscopy.

PubMed

Congdon, N G; Spaeth, G L; Augsburger, J; Klancnik, J; Patel, K; Hunter, D G

1999-11-01

To design a system of gonioscopy that will allow greater interobserver reliability and more clearly defined screening cutoffs for angle closure than current systems while being simple to teach and technologically appropriate for use in rural Asia, where the prevalence of angle-closure glaucoma is highest. Clinic-based validation and interobserver reliability trial. Study 1: 21 patients 18 years of age and older recruited from a university-based specialty glaucoma clinic; study 2: 32 patients 18 years of age and older recruited from the same clinic. In study 1, all participants underwent conventional gonioscopy by an experienced observer (GLS) using the Spaeth system and in the same eye also underwent Scheimpflug photography, ultrasonographic measurement of anterior chamber depth and axial length, automatic refraction, and biometric gonioscopy with measurement of the distance from iris insertion to Schwalbe's line using a reticule based in the slit-lamp ocular. In study 2, all participants underwent both conventional gonioscopy and biometric gonioscopy by an experienced gonioscopist (NGC) and a medical student with no previous training in gonioscopy (JK). Study 1: The association between biometric gonioscopy and conventional gonioscopy, Scheimpflug photography, and other factors known to correlate with the configuration of the angle. Study 2: Interobserver agreement using biometric gonioscopy compared to that obtained with conventional gonioscopy. In study 1, there was an independent, monotonic, statistically significant relationship between biometric gonioscopy and both Spaeth angle (P = 0.001, t test) and Spaeth insertion (P = 0.008, t test) grades. Biometric gonioscopy correctly identified six of six patients with occludable angles according to Spaeth criteria. Biometric gonioscopic grade was also significantly associated with the anterior chamber angle as measured by Scheimpflug photography (P = 0.005, t test). In study 2, the intraclass correlation coefficient between graders for biometric gonioscopy (0.97) was higher than for Spaeth angle grade (0.72) or Spaeth insertion grade (0.84). Biometric gonioscopy correlates well with other measures of the anterior chamber angle, shows a higher degree of interobserver reliability than conventional gonioscopy, and can readily be learned by an inexperienced observer.

A Case of Retained Graphite Anterior Chamber Foreign Body Masquerading as Stromal Keratitis

PubMed Central

Han, Eun Ryung; Wee, Won Ryang; Lee, Jin Hak

2011-01-01

We report a case of a retained graphite anterior chamber foreign body that was masquerading as stromal keratitis. A 28-year-old male visited with complaints of visual disturbance and hyperemia in his right eye for four weeks. On initial examination, he presented with a stromal edema involving the inferior half of the cornea, epithelial microcysts, and moderate chamber inflammation. Suspecting herpetic stromal keratitis, he was treated with anti-viral and anti-inflammatory agents. One month after the initial visit, anterior chamber inflammation was improved and his visual acuity recovered to 20/20, but subtle corneal edema still remained. On tapering the medication, after three months, a foreign body was incidentally identified in the inferior chamber angle and was surgically removed resulting in complete resolution of corneal edema. The removed foreign body was a fragment of graphite and he subsequently disclosed a trauma with mechanical pencil 12 years earlier. This case showed that the presence of an anterior chamber foreign body should always be considered in the differential diagnosis of idiopathic localized corneal edema. PMID:21461226

Clinical and Anterior Segment Anatomical Features in Primary Angle Closure Subgroups Based on Configurations of Iris Root Insertion.

PubMed

Hong, Ji Wook; Yun, Sung-Cheol; Sung, Kyung Rim; Lee, Jong Eun

2016-06-01

To compare the clinical and anterior segment anatomical features in primary angle closure sub-groups based on configurations of iris root insertion. Primary angle closure patients were imaged using anterior segment optical coherence tomography. Anterior chamber depth, iris curvature, iris thickness (IT) at the scleral spur and 500, 750, and 1,500 µm from the scleral spur (IT0, IT500, IT750, and IT1500), lens vault, iris area, angle opening distance (AOD500), angle recess area (ARA750), and trabecular iris space area (TISA750) were measured. Iris root insertion was categorized into a non-basal insertion group (NBG) and basal insertion group (BG). In total, 43 eyes of 39 participants belonged to the NBG and 89 eyes of 53 participants to the BG. The mean age of participants was greater in the NBG than the BG (62.7 ± 5.7 vs. 59.8 ± 7.3 years, p = 0.043), and the baseline intraocular pressure was higher in the BG than the NBG (16.4 ± 4.4 vs. 14.9 ± 3.3 mmHg, p = 0.037). The BG showed a greater IT0 (0.265 ± 0.04 vs. 0.214 ± 0.03 mm, p < 0.001) and iris area (1.59 ± 0.24 vs. 1.52 ± 0.27 mm(2), p = 0.045), lower ARA750 (0.112 ± 0.08 vs. 0.154 ± 0.08 mm(2), p = 0.017) and AOD500 (0.165 ± 0.07 vs. 0.202 ± 0.08 mm, p = 0.014) compared to the NBG. The BG had a narrower anterior chamber angle, thicker peripheral iris, and higher pretreatment intraocular pressure.

Anterior segment biometry during accommodation imaged with ultra-long scan depth optical coherence tomography

PubMed Central

Du, Chixin; Shen, Meixiao; Li, Ming; Zhu, Dexi; Wang, Michael R.; Wang, Jianhua

2012-01-01

Purpose To measure by ultra-long scan depth optical coherence tomography (UL-OCT) dimensional changes in the anterior segment of human eyes during accommodation. Design Evaluation of diagnostic test or technology. Participants Forty-one right eyes of healthy subjects with a mean age of 34 years (range, 22–41 years) and a mean refraction of −2.5±2.6 diopters (D) were imaged in two repeated measurements at minimal and maximal accommodation. Methods A specially adapted designed UL-OCT instrument was used to image from the front surface of the cornea to the back surface of the crystalline lens. Custom software corrected the optical distortion of the images and yielded the biometric measurements. The coefficient of repeatability (COR) and the intraclass correlation coefficient (ICC) were calculated to evaluate the repeatability and reliability. Main Outcome Measures Anterior segment parameters and associated repeatability and reliability upon accommodation. The dimensional results included central corneal thickness (CCT), anterior chamber depth and width (ACD, ACW), pupil diameter (PD), lens thickness (LT), anterior segment length (ASL=ACD+LT), lens central position (LCP=ACD+1/2LT) and horizontal radii of the lens anterior and posterior surface curvatures (LAC, LPC). Results Repeated measurements of each variable within each accommodative state did not differ significantly (P>0.05). The CORs and ICCs for CCT, ACW, ACD, LT, LCP, and ASL were excellent (1.2% to 3.59% and 0.998 to 0.877, respectively). They were higher for PD (18.90% to 21.63% and 0.880 to 0.874, respectively), and moderate for LAC and LPC (34.86% to 42.72% and 0.669 to 0.251, respectively) in the two accommodative states. Compared to minimal accommodation, PD, ACD, LAC, LPC, and LCP decreased and LT and ASL increased significantly at maximal accommodation (P<0.05), while CCT and ACW did not change (P>0.05). Conclusions UL-OCT measured changes in anterior segment dimensions during accommodation with good repeatability and reliability. During accommodation, the back surface of the lens became steeper as the lens moved forward. PMID:22902211

Ultrasonographic and macroscopic anatomy of the enucleated eyes of the buffalo (Bos bubalis) and the one-humped camel (Camelus dromedarius) of different ages.

PubMed

Kassab, A

2012-02-01

The ultrasonographic appearance and measurements of the normal buffalo and camel eye globes were described in 60 buffaloes (Bos bubalis) aged 1 year (28 eyes) and 10 years (32 eyes), and in 51 humped camels (Camelus dromedarius) aged 1 year (26 eyes) and 10 years (24 eyes). Ocular measurements were recorded by A- and B-scan ultrasonographic examination of 40 buffalo eyes (18 young and 22 adult eyes) and 34 camel eyes (14 young and 20 adult eyes) using a KANGH ultrasound scanner equipped with 10 MHz probe. For gross measurements, 20 buffalo and 16 camel eye globes were frozen and dissected and the same measurements were made using fine callipers macroscopically. The aqueous and vitreous humour of the buffalo and camel eyes appeared anechoic. The cornea, anterior and posterior lens capsule and iris appeared hyperechoic. The ocular measurements for the axial length, vitreous chamber depth (VCD), corneal thickness, lens thickness and scleroretinal rim thickness increase with the advance of age in both buffaloes and camels. Except for the anterior chamber depth, VCD and lens thickness, which were larger in adult camels than in adult buffaloes, no other differences between ocular dimensions were observed in both species. The results of this study are valuable for comparative ocular anatomy and will be useful for ultrasonographic evaluation of ocular diseases in buffaloes and camels. © 2011 Blackwell Verlag GmbH.

The Relationship between Crystalline Lens Power and Refractive Error in Older Chinese Adults: The Shanghai Eye Study.

PubMed

He, Jiangnan; Lu, Lina; He, Xiangui; Xu, Xian; Du, Xuan; Zhang, Bo; Zhao, Huijuan; Sha, Jida; Zhu, Jianfeng; Zou, Haidong; Xu, Xun

2017-01-01

To report calculated crystalline lens power and describe the distribution of ocular biometry and its association with refractive error in older Chinese adults. Random clustering sampling was used to identify adults aged 50 years and above in Xuhui and Baoshan districts of Shanghai. Refraction was determined by subjective refraction that achieved the best corrected vision based on monocular measurement. Ocular biometry was measured by IOL Master. The crystalline lens power of right eyes was calculated using modified Bennett-Rabbetts formula. We analyzed 6099 normal phakic right eyes. The mean crystalline lens power was 20.34 ± 2.24D (range: 13.40-36.08). Lens power, spherical equivalent, and anterior chamber depth changed linearly with age; however, axial length, corneal power and AL/CR ratio did not vary with age. The overall prevalence of hyperopia, myopia, and high myopia was 48.48% (95% CI: 47.23%-49.74%), 22.82% (95% CI: 21.77%-23.88%), and 4.57% (95% CI: 4.05-5.10), respectively. The prevalence of hyperopia increased linearly with age while lens power decreased with age. In multivariate models, refractive error was strongly correlated with axial length, lens power, corneal power, and anterior chamber depth; refractive error was slightly correlated with best corrected visual acuity, age and sex. Lens power, hyperopia, and spherical equivalent changed linearly with age; Moreover, the continuous loss of lens power produced hyperopic shifts in refraction in subjects aged more than 50 years.

Anterior chamber paracentesis to improve diagnosis and treatment of infectious uveitis in South Africa.

PubMed

Schaftenaar, Erik; Lecuona, Karin; Baarsma, Seerp; Meenken, Christina; Verjans, Georges; McIntyre, James; Peters, Remco

2015-09-22

Infectious uveitis is a significant cause of blindness in South Africa, especially among HIV-infected individuals. The visual outcome of uveitis depends on early clinical and laboratory diagnosis to guide therapeutic intervention. Analyses of aqueous humor, obtained by anterior chamber paracentesis, directs the differential diagnosis in infectious uveitis. However, although safe and potentially cost-effective, diagnostic anterior chamber paracentesis is not common practice in ophthalmic care across Africa. We seek to draw attention to this important procedure that could improve the diagnosis and prognosis of infectious uveitis.

Comparison of Scheimpflug imaging and spectral domain anterior segment optical coherence tomography for detection of narrow anterior chamber angles.

PubMed

Grewal, D S; Brar, G S; Jain, R; Grewal, S P S

2011-05-01

To compare the performance of anterior chamber volume (ACV) and anterior chamber depth (ACD) obtained using Scheimpflug imaging with angle opening distance (AOD500) and trabecular-iris space area (TISA500) obtained using spectral domain anterior segment optical coherence tomography (SD-ASOCT) in detecting narrow angles classified using gonioscopy. In this prospective, cross-sectional observational study, 265 eyes of 265 consecutive patients underwent sequential Scheimpflug imaging, SD-ASOCT imaging, and gonioscopy. Correlations between gonioscopy grading, ACV, ACD, AOD500, and TISA500 were evaluated. Area under receiver operating characteristic curve (AUC), sensitivity, specificity, and likelihood ratios (LRs) were calculated to assess the performance of ACV, ACD, AOD500, and TISA500 in detecting narrow angles (defined as Shaffer grade ≤1 in all quadrants). SD-ASOCT images were obtained at the nasal and temporal quadrants only. Twenty-eight eyes (10.6%) were classified as narrow angles on gonioscopy. ACV correlated with gonioscopy grading (P<0.001) for temporal (r=0.204), superior (r=0.251), nasal (r=0.213), and inferior (r=0.236) quadrants. ACV correlated with TISA500 for nasal (r=0.135, P=0.029) and temporal (P=0.160, P=0.009) quadrants and also with AOD500 for nasal (r=0.498, P<0.001) and temporal (r=0.517, P<0.001) quadrants. For detection of narrow angles, ACV (AUC=0.935; 95% confidence interval (CI) =0.898-0.961) performed similar to ACD (AUC=0.88, P=0.06) and significantly better than AOD500 nasal (AUC=0.761, P=0.001), AOD500 temporal (AUC=0.808, P<0.001), TISA500 nasal (AUC=0.756, P<0.001), and TISA500 temporal (AUC=0.738, P<0.001). Using a cutoff of 113 mm(3), ACV had 90% sensitivity and 88% specificity for detecting narrow angles. Positive and negative LRs for ACV were 8.63 (95% CI=7.4-10.0) and 0.11 (95% CI=0.03-0.4), respectively. ACV measurements using Scheimpflug imaging outperformed AOD500 and TISA500 using SD-ASOCT for detecting narrow angles.

Predictors of intraocular pressure change after phacoemulsification in patients with pseudoexfoliation syndrome.

PubMed

Moghimi, Sasan; Johari, Mohammadkarim; Mahmoudi, Alireza; Chen, Rebecca; Mazloumi, Mehdi; He, Mingguang; Lin, Shan C

2017-03-01

To evaluate anterior chamber biometric factors and intraoperative metrics associated with the intraocular pressure (IOP) reduction after phacoemulsification in non-glaucomatous pseudoexfoliative syndrome (PXS) eyes. Thirty-three patients were enrolled in this prospective interventional study. Images were excluded if they had poor quality, poor perpendicularity or inability to locate sclera spurs. Anterior chamber depth (ACD), anterior chamber area (ACA), iris thickness, iris area, iris curvature, lens vault, angle opening distance (AOD500, AOD750) and trabecular iris space area (TISA500, TISA750) were measured in qualified images using the Zhongshan Angle Assessment Program and compared preoperatively and 3 months postoperatively. Cumulative dissipated energy (CDE), aspiration time and infusion fluid usage during cataract surgery were obtained from the phacoemulsification machine's metrics record. Postoperative IOP change was compared with these anatomical and intraoperative metric parameters. Mean IOP was 18.1±3.4 mm Hg preoperatively and decreased by 3.3 mm Hg (18%) to 14.8±3.6 mm Hg at 3 months postoperatively (p<0.001). All angle parameters, ACD and ACA increased significantly postoperatively (p<0.001 for all) and iris curvature decreased (p<0.001). In univariate analysis, preoperative IOP (B=-0.668, p=0.002), infusion fluid usage (B=-0.040, p=0.04) and aspiration time (B=-0.045, p=0.003) were negatively associated with IOP decrease after phacoemulsification. Changes in IOP did not demonstrate significant associations with CDE measurements or anterior segment optical coherence tomography measurements, including preoperative angle, iris or anterior segment parameters. In the final multivariate regression model, preoperative IOP (B=-0.668, p=0.002) and infusion fluid usage (B=-0.041, p=0.04) were significantly associated with IOP drop and together can predict 45.1% (p=0.002) of the variability in IOP change. Non-glaucomatous patients with PXS experience moderate IOP reduction following phacoemulsification, and this effect is correlated with preoperative IOP, aspiration time and infusion fluid used intraoperatively. 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/.

Clinical and ultrasonographic findings of some ocular conditions in sheep and goats

PubMed Central

El-Tookhy, O.; Tharwat, M.

2013-01-01

This study was carried out to describe the ultrasonographic findings in relation to the clinical symptoms of some common ocular conditions in sheep and goats. Fifty animals (32 goats and 18 sheep) with different ocular problems were examined. Ultrasonographic examination was performed using a B-mode ocular ultrasound unit, and the structure of the globe was evaluated at a depth of 4-6 cm. Early cases (n=35, 70%) showed varying ocular conditions; hypopyon, (n=8, 16%), stromal abscesses, (n=4, 8%), and anterior uveitis (n=23, 46%). Hypopyon appeared clinically as a white or yellowish material in the anterior chamber, and ultrasonographically as a hyperechoic mass in the anterior chamber. Severe iridocyclitis was noticed in acute cases of infectious keratoconjunctivitis (IKC) accompanied by blepharospasm, photophobia, excessive tearing and eyelid margin crust formation. Ultrasonographically, the pupil appeared constricted with increased hyperechoic thickening of the ciliary body. In chronic cases of IKC, corneal pigmentation (n=5, 10%) and cataract (n=10, 20%) were seen. Ultrasonographically the type and degree of cataract were diagnosed. The present study provides an inside view of the inner ocular structures during the course of certain eye diseases where ophthalmoscopic examination is not possible. Our findings, although preliminary, are relevant for the more complete diagnosis of certain external ocular conditions in sheep and goat herds. PMID:26623306

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.

Implantation of ArtificialIris, a CustomFlex irisprosthesis, in a trauma patient with an Artisan lens

PubMed Central

Doroodgar, Farideh; Jabbarvand, Mahmoud; Niazi, Feizollah; Niazi, Sana; Sanginabadi, Azad

2017-01-01

Abstract Purpose: To evaluate probable complications of ArtificialIris implantation with iris fixated intraocular lens. Method: Development of photophobia, glare, and psychological strain during face-to-face communication in a 23-year-old man with a widespread traumatic iris defect terminate to make a decision for performing implantation of an ArtificialIris (Humanoptics, Erlangen, Germany) under the remnant iris without removing the patient's existing Artisan lens. Results: Without any intraoperative or postoperative complications, the patient's visual acuity increased by 1 line, the endothelial cell loss was comparable with the cell loss associated with standard cataract surgery, and the anterior-chamber depth and anterior-chamber anatomy did not change. At the final follow-up examination, the mean intraocular pressure did not differ from baseline, and we achieved high level of patient satisfaction and subjective vision improvement. We discuss the particular importance of considering the patient's expectations, the appropriate measurements, ways to perfect color evaluation, and the types of ArtificialIris products. Conclusion: The implantation of the ArtificialIris in patients with aphakic iris-supported lenses (ie, pre-existing Artisan lenses) is a feasible approach and a useful option for patients with thin irises and iris hypoplasia who are at risk of subluxation or the dislocation of the posterior-chamber intraocular lens (PCIOL), and also those with sclerally fixed PCIOLs. PMID:29137026

OCT-based crystalline lens topography in accommodating eyes.

PubMed

Pérez-Merino, Pablo; Velasco-Ocana, Miriam; Martinez-Enriquez, Eduardo; Marcos, Susana

2015-12-01

Custom Spectral Domain Optical Coherence Tomography (SD-OCT) provided with automatic quantification and distortion correction algorithms was used to measure anterior and posterior crystalline lens surface elevation in accommodating eyes and to evaluate relationships between anterior segment surfaces. Nine young eyes were measured at different accommodative demands. Anterior and posterior lens radii of curvature decreased at a rate of 0.78 ± 0.18 and 0.13 ± 0.07 mm/D, anterior chamber depth decreased at 0.04 ± 0.01 mm/D and lens thickness increased at 0.04 ± 0.01 mm/D with accommodation. Three-dimensional surface elevations were estimated by subtracting best fitting spheres. In the relaxed state, the spherical term accounted for most of the surface irregularity in the anterior lens (47%) and astigmatism (70%) in the posterior lens. However, in accommodated lenses astigmatism was the predominant surface irregularity (90%) in the anterior lens. The RMS of high-order irregularities of the posterior lens surface was statistically significantly higher than that of the anterior lens surface (x2.02, p<0.0001). There was significant negative correlation in vertical coma (Z3 (-1)) and oblique trefoil (Z3 (-3)) between lens surfaces. The astigmatic angle showed high degree of alignment between corneal surfaces, moderate between corneal and anterior lens surface (~27 deg), but differed by ~80 deg between the anterior and posterior lens surfaces (including relative anterior/posterior lens astigmatic angle shifts (10-20 deg).

OCT-based crystalline lens topography in accommodating eyes

PubMed Central

Pérez-Merino, Pablo; Velasco-Ocana, Miriam; Martinez-Enriquez, Eduardo; Marcos, Susana

2015-01-01

Custom Spectral Domain Optical Coherence Tomography (SD-OCT) provided with automatic quantification and distortion correction algorithms was used to measure anterior and posterior crystalline lens surface elevation in accommodating eyes and to evaluate relationships between anterior segment surfaces. Nine young eyes were measured at different accommodative demands. Anterior and posterior lens radii of curvature decreased at a rate of 0.78 ± 0.18 and 0.13 ± 0.07 mm/D, anterior chamber depth decreased at 0.04 ± 0.01 mm/D and lens thickness increased at 0.04 ± 0.01 mm/D with accommodation. Three-dimensional surface elevations were estimated by subtracting best fitting spheres. In the relaxed state, the spherical term accounted for most of the surface irregularity in the anterior lens (47%) and astigmatism (70%) in the posterior lens. However, in accommodated lenses astigmatism was the predominant surface irregularity (90%) in the anterior lens. The RMS of high-order irregularities of the posterior lens surface was statistically significantly higher than that of the anterior lens surface (x2.02, p<0.0001). There was significant negative correlation in vertical coma (Z3−1) and oblique trefoil (Z3−3) between lens surfaces. The astigmatic angle showed high degree of alignment between corneal surfaces, moderate between corneal and anterior lens surface (~27 deg), but differed by ~80 deg between the anterior and posterior lens surfaces (including relative anterior/posterior lens astigmatic angle shifts (10-20 deg). PMID:26713216

Fixed dilated pupil (Urrets-Zavalia syndrome) after air/gas injection after deep lamellar keratoplasty for keratoconus.

PubMed

Maurino, Vincenzo; Allan, Bruce D S; Stevens, Julian D; Tuft, Stephen J

2002-02-01

To describe three cases of fixed dilated pupil and presumed iris ischemia (Urrets-Zavalia syndrome) after anterior chamber air/gas injection after deep lamellar keratoplasty for keratoconus. Interventional case series. Three eyes of three patients with keratoconus underwent deep lamellar keratoplasty and intraoperative or postoperative injection of air/gas in the anterior chamber to appose the host-donor lamellar graft interface. Urrets-Zavalia syndrome was diagnosed on clinical grounds in three cases and was associated with the Descemet membrane microperforation intraoperatively and introduction of air/gas into the anterior chamber intraoperatively or postoperatively. A fixed dilated pupil is an uncommon complication of penetrating keratoplasty for keratoconus that can also develop after deep lamellar keratoplasty. Leaving an air or gas bubble in the anterior chamber of a phakic eye after deep lamellar keratoplasty is a risk factor and should therefore be avoided.

Relationship between intraocular pressure and angle configuration: an anterior segment OCT study.

PubMed

Chong, Rachel S; Sakata, Lisandro M; Narayanaswamy, Arun K; Ho, Sue-Wei; He, Mingguang; Baskaran, Mani; Wong, Tien Yin; Perera, Shamira A; Aung, Tin

2013-03-05

To assess the relationship between intraocular pressure (IOP) and anterior chamber angle (ACA) configuration as assessed by gonioscopy and anterior segment optical coherence tomography (AS-OCT). A total of 2045 subjects aged 50 years and older, were recruited from a community clinic and underwent AS-OCT, Goldmann applanation tonometry, and gonioscopy. A quadrant was classified as closed on gonioscopy if the posterior trabecular meshwork could not be seen. A closed quadrant on AS-OCT was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. Customized software (Zhongshan Angle Assessment Program, Guangzhou, China) was used to measure AS-OCT parameters on AS-OCT scans, including anterior chamber depth, area, and volume; iris thickness (IT) and curvature; lens vault; angle opening distance; and trabecular-iris space area. IOP values were adjusted for age, sex, diabetes and hypertension status, body mass index, central corneal thickness, and presence of peripheral anterior synechiae. Mean age of study subjects was 63.2 ± 8.0 years, 52.6% were female, and 89.4% were Chinese. Mean IOP was 14.8 ± 2.4 mm Hg (range 826). IOP (mean ± SE) increased with number of quadrants with gonioscopic angle closure (none: 14.6 ± 0.2; one: 14.7 ± 0.3; two: 15.0 ± 0.3; three: 15.0 ± 0.3; four: 15.6 ± 0.3 mm Hg; P < 0.001), and on AS-OCT (none: 14.7 ± 0.2; one: 15.0 ± 0.2; two: 14.8 ± 0.2; three: 15.1 ± 0.3; four: 16.0 ± 0.3 mm Hg; P < 0.001). IOP also increased in association with most of the ACA quantitative parameters measured on AS-OCT images, except for IT and lens vault. There was an association between the extent of angle closure, as assessed on AS-OCT and gonioscopy, with increasing IOP.

The effect of internal fixation lamp on anterior chamber angle width measured by anterior segment optical coherence tomography.

PubMed

Nakamine, Sakari; Sakai, Hiroshi; Arakaki, Yoshikuni; Yonahara, Michiko; Kaiya, Tadayoshi

2018-01-01

To study the effect of the internal fixation lamp on anterior chamber width measured by anterior segment optical coherence tomography. In a prospective cross sectional observational study, consecutive 22 right eyes of 22 patients (4 men and 18 women) with suspected primary angle closure underwent swept source domain anterior segment optical coherence tomography (AS-OCT), (CASIA SS-1000, Tomey, Nagoya, Japan). Anterior chamber parameters of angle opening distance (AOD), trabecular-iris angle (TIA), angle recess area (ARA) at 500 or 750 µm from scleral spur and pupil diameter were measured by AS-OCT in a three-dimensional mode in 4 quadrants (superior, inferior, temporal and nasal) in dark room setting both with and without internal fixation lamp. Anterior segment parameters of AOD 500 in superior, inferior and temporal quadrants, AOD 750 at superior and nasal, TIA 500 at superior, and inferior and TIA 750 at superior and nasal, and ARA 500 or 750 at superior and inferior with internal fixation lamp were greater and the pupil diameter was significantly (all P < 0.05, paired t test) smaller than when measured without fixation lamp. Internal fixation lamp of the anterior segment OCT makes the pupil constrict and angle wider. When using AS-OCT with usual setting with internal fixation lamp on with eyes in which the anterior chamber angle is narrow but open, it is recommended that the internal fixation lamp be turned off to ensure a clear indication as to whether the angle is open or closed in the dark.

Comparison of anterior chamber depth measurements by 3-dimensional optical coherence tomography, partial coherence interferometry biometry, Scheimpflug rotating camera imaging, and ultrasound biomicroscopy.

PubMed

Nakakura, Shunsuke; Mori, Etsuko; Nagatomi, Nozomi; Tabuchi, Hitoshi; Kiuchi, Yoshiaki

2012-07-01

To evaluate the congruity of anterior chamber depth (ACD) measurements using 4 devices. Saneikai Tsukazaki Hospital, Himeji City, Japan. Comparative case series. In 1 eye of 42 healthy participants, the ACD was measured by 3-dimensional corneal and anterior segment optical coherence tomography (CAS-OCT), partial coherence interferometry (PCI), Scheimpflug imaging, and ultrasound biomicroscopy (UBM). The differences between the measurements were evaluated by 2-way analysis of variance and post hoc analysis. Agreement between the measurements was evaluated using Bland-Altman analysis. To evaluate the true ACD using PCI, the automatically calculated ACD minus the central corneal thickness measured by CAS-OCT was defined as PCI true. Two ACD measurements were also taken with CAS-OCT. The mean ACD was 3.72 mm ± 0.23 (SD) (PCI), 3.18 ± 0.23 mm (PCI true), 3.24 ± 0.25 mm (Scheimpflug), 3.03 ± 0.25 mm (UBM), 3.14 ± 0.24 mm (CAS-OCT auto), and 3.12 ± 0.24 mm (CAS-OCT manual). A significant difference was observed between PCI biometry, Scheimpflug imaging, and UBM measurements and the other methods. Post hoc analysis showed no significant differences between PCI true and CAS-OCT auto or between CAS-OCT auto and CAS-OCT manual. Strong correlations were observed between all measurements; however, Bland-Altman analysis showed good agreement only between PCI true and Scheimpflug imaging and between CAS-OCT auto and CAS OCT manual. The ACD measurements obtained from PCI biometry, Scheimpflug imaging, CAS-OCT, and UBM were significantly different and not interchangeable except for PCI true and CAS-OCT auto and CAS-OCT auto and CAS-OCT manual. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

PLATEAU IRIS SYNDROME--CASE SERIES.

PubMed

Feraru, Crenguta Ioana; Pantalon, Anca Delia; Chiselita, Dorin; Branisteanu, Daniel

2015-01-01

Plateau iris is characterized by closing the anterior chamber angle due to a large ciliary body or due to its anterior insertion that alters the position of iris periphery in respect to the trabecular meshwork. There are two aspects that need to be differentiated: plateau iris configuration and plateau iris syndrome. The first describes a situation when the iris root is flat and the anterior chamber is not shallow, the latter refers to a post laser iridotomy condition in which a patent iridotomy has removed the relative pupillary block, but goniscopically confirmed angle closure recurs without central shallowing of the anterior chamber. Isolated plateau iris syndrome is rare compared to plateau iris configuration. We hereby present two case reports of plateau iris syndrome in young patients who came to an ophthalmologic consult by chance.

Spontaneous anterior chamber hemorrhage from the iris: a unique cinematographic documentation.

PubMed Central

Welch, R B

1980-01-01

A 54-year-old white female was observed with an apparent spontaneous idiopathic anterior chamber hemorrhage from the pupillary border of the iris. This event was documented by cinematography. A review of the literature concerning anterior chamber hemorrhage is presented and reports of spontaneous hyphema enumerated. The relationship of the entity of pupillary vascular tufts to the present report are discussed and etiologic factors considered. It is apparent that closer scrutiny of the pupillary border should be performed and iris angiography obtained in a variety of eyes to delineate normal and abnormal variants. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 PMID:6167051

The Relationship between Crystalline Lens Power and Refractive Error in Older Chinese Adults: The Shanghai Eye Study

PubMed Central

He, Jiangnan; Lu, Lina; He, Xiangui; Xu, Xian; Du, Xuan; Zhang, Bo; Zhao, Huijuan; Sha, Jida; Zhu, Jianfeng; Zou, Haidong; Xu, Xun

2017-01-01

Purpose To report calculated crystalline lens power and describe the distribution of ocular biometry and its association with refractive error in older Chinese adults. Methods Random clustering sampling was used to identify adults aged 50 years and above in Xuhui and Baoshan districts of Shanghai. Refraction was determined by subjective refraction that achieved the best corrected vision based on monocular measurement. Ocular biometry was measured by IOL Master. The crystalline lens power of right eyes was calculated using modified Bennett-Rabbetts formula. Results We analyzed 6099 normal phakic right eyes. The mean crystalline lens power was 20.34 ± 2.24D (range: 13.40–36.08). Lens power, spherical equivalent, and anterior chamber depth changed linearly with age; however, axial length, corneal power and AL/CR ratio did not vary with age. The overall prevalence of hyperopia, myopia, and high myopia was 48.48% (95% CI: 47.23%–49.74%), 22.82% (95% CI: 21.77%–23.88%), and 4.57% (95% CI: 4.05–5.10), respectively. The prevalence of hyperopia increased linearly with age while lens power decreased with age. In multivariate models, refractive error was strongly correlated with axial length, lens power, corneal power, and anterior chamber depth; refractive error was slightly correlated with best corrected visual acuity, age and sex. Conclusion Lens power, hyperopia, and spherical equivalent changed linearly with age; Moreover, the continuous loss of lens power produced hyperopic shifts in refraction in subjects aged more than 50 years. PMID:28114313

Heritability of myopia and ocular biometrics in Koreans: the healthy twin study.

PubMed

Kim, Myung Hun; Zhao, Di; Kim, Woori; Lim, Dong-Hui; Song, Yun-Mi; Guallar, Eliseo; Cho, Juhee; Sung, Joohon; Chung, Eui-Sang; Chung, Tae-Young

2013-05-01

To estimate the heritabilities of myopia and ocular biometrics among different family types among a Korean population. We studied 1508 adults in the Healthy Twin Study. Spherical equivalent, axial length, anterior chamber depth, and corneal astigmatism were measured by refraction, corneal topography, and A-scan ultrasonography. To see the degree of resemblance among different types of family relationships, intraclass correlation coefficients (ICC) were calculated. Variance-component methods were applied to estimate the genetic contributions to eye phenotypes as heritability based on the maximum likelihood estimation. Narrow sense heritability was calculated as the proportion of the total phenotypic variance explained by additive genetic effects, and linear and nonlinear effects of age, sex, and interactions between age and sex were adjusted. A total of 240 monozygotic twin pairs, 45 dizygotic twin pairs, and 938 singleton adult family members who were first-degree relatives of twins in 345 families were included in the study. ICCs for spherical equivalent from monozygotic twins, pooled first-degree pairs, and spouse pairs were 0.83, 0.34, and 0.20, respectively. The ICCs of other ocular biometrics were also significantly higher in monozygotic twins compared with other relative pairs, with greater consistency and conformity. The estimated narrow sense heritability (95% confidence interval) was 0.78 (0.71-0.84) for spherical equivalent; 0.86 (0.82-0.90) for axial length; 0.83 (0.76-0.91) for anterior chamber depth; and 0.70 (0.63-0.77) for corneal astigmatism. The estimated heritability of spherical equivalent and ocular biometrics in the Korean population suggests the compelling evidence that all traits are highly heritable.

Macular Structures, Optical Components, and Visual Acuity in Preschool Children after Intravitreal Bevacizumab or Laser Treatment.

PubMed

Lee, Yung-Sung; See, Lai-Chu; Chang, Shu-Hao; Wang, Nan-Kai; Hwang, Yih-Shiou; Lai, Chi-Chun; Chen, Kuan-Jen; Wu, Wei-Chi

2018-05-10

To investigate the macular structures, optical components, and visual acuity in preschool-aged children with a history of type I retinopathy of prematurity who underwent either intravitreal bevacizumab (IVB), laser, or a combination of treatments. Comparative interventional case series. A referred medical center in Taiwan. 80 eyes from 42 patients (33 IVB-treated eyes from 17 children, 24 laser-treated eyes from 13 children, and 23 laser + IVB-treated eyes from 12 children). Spectral-domain optical coherence tomography. The retinal thickness in the foveal area and the associated morphologic changes in foveal depression. Compared with the laser-treated and laser + IVB-treated eyes, the IVB-treated eyes had less myopia and deeper anterior chamber depths but presented similar axial lengths and corneal curvatures (P = .001, .002, .95 and .16, respectively). The IVB-treated eyes had significantly thinner foveal, parafoveal, and perifoveal retinal thicknesses (P < .01 for all) and a higher incidence of foveal depression than the laser- or laser + IVB-treated eyes. The macular and subfoveal choroidal thicknesses did not differ among the groups (P = .21 and .63, respectively). Moreover, compared with the eyes treated with laser or laser + IVB, the IVB-treated eyes had better uncorrected visual acuity, although a significant difference was not observed in best-corrected visual acuity (P = .008 and .29, respectively). Compared with laser therapy, IVB-treated eyes were associated with deeper anterior chamber depths and thinner foveal, parafoveal and perifoveal thicknesses. Moreover, these IVB-treated eyes had less refractive errors and better uncorrected visual acuity. Copyright © 2018. Published by Elsevier Inc.

Comparability of anterior chamber depth measurements with partial coherence interferometry and optical low-coherence reflectometry in pseudophakic eyes.

PubMed

Luft, Nikolaus; Hirnschall, Nino; Farrokhi, Sanaz; Findl, Oliver

2015-08-01

To assess whether anterior chamber depth (ACD) measurements in pseudophakic eyes obtained with partial coherence interferometry (PCI) and optical low-coherence reflectometry (OLCR) devices can be used interchangeably. Vienna Institute for Research in Ocular Surgery, A Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria. Prospective case series. The ACD measurements in 1 eye of each pseudophakic patient were performed with the PCI-based ACMaster device and the OLCR-based Lenstar LS900 device at least 1 day postoperatively. The study comprised 65 eyes of 65 patients with a mean age of 71.7 years ± 9.0 (SD) (range 39 to 91 years). In 15 eyes, no valid ACD readings could be obtained with the OLCR device. No obvious reason for these measurement failures was identified; however, tear-film alterations shortly after surgery were suspected. No significant difference in the mean ACD in the remaining 50 eyes was found between PCI measurements (5019 ± 660 μm; range 4008 to 6181 μm) and OLCR measurements (5015 ± 663 μm; range 4017 to 6163 μm) (P = .06). Three (6%) of 50 measurements were not within the 95% limits of agreement in the Bland-Altman analysis. Pseudophakic ACD measurements with the PCI and OLCR devices can be used interchangeably. The OLCR device proved to be more user-friendly and faster; however, in a substantial number of eyes, no usable values were obtainable. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Comparison of two Nd:YAG laser posterior capsulotomy: cruciate pattern vs circular pattern with vitreous strand cutting

PubMed Central

Kim, Jin-Soo; Choi, Jung Yeol; Kwon, Ji-Won; Wee, Won Ryang; Han, Young Keun

2018-01-01

AIM To investigate the effects and safety of neodymium: yttrium-aluminium-garnet (Nd:YAG) laser posterior capsulotomy with vitreous strand cutting METHODS A total of 40 eyes of 37 patients with symptomatic posterior capsular opacity (PCO) were included in this prospective randomized study and were randomly subjected to either cruciate pattern or round pattern Nd:YAG posterior capsulotomy with vitreous strand cutting (modified round pattern). The best corrected visual acuity (BCVA), intraocular pressure (IOP), refractive error, endothelial cell count (ECC), anterior segment parameters, including anterior chamber depth (ACD) and anterior chamber angle (ACA) were measured before and 1mo after the laser posterior capsulotomy. RESULTS In both groups, the BCVA improved significantly (P<0.001 for the modified round pattern group, P=0.001 for the cruciate pattern group); the IOP and ECC did not significantly change. The ACD significantly decreased (P<0.001 for both) and the ACA significantly increased (P=0.001 for the modified round pattern group and P=0.034 for the cruciate group). The extent of changes in these parameters was not significantly different between the groups. CONCLUSION Modified round pattern Nd:YAG laser posterior capsulotomy is an effective and safe method for the treatment of PCO. This method significantly changes the ACD and ACA, but the change in refraction is not significant. Modified round pattern Nd:YAG laser posterior capsulotomy can be considered a good alternative procedure in patients with symptomatic PCO. PMID:29487812

Comparison of two Nd:YAG laser posterior capsulotomy: cruciate pattern vs circular pattern with vitreous strand cutting.

PubMed

Kim, Jin-Soo; Choi, Jung Yeol; Kwon, Ji-Won; Wee, Won Ryang; Han, Young Keun

2018-01-01

To investigate the effects and safety of neodymium: yttrium-aluminium-garnet (Nd:YAG) laser posterior capsulotomy with vitreous strand cutting. A total of 40 eyes of 37 patients with symptomatic posterior capsular opacity (PCO) were included in this prospective randomized study and were randomly subjected to either cruciate pattern or round pattern Nd:YAG posterior capsulotomy with vitreous strand cutting (modified round pattern). The best corrected visual acuity (BCVA), intraocular pressure (IOP), refractive error, endothelial cell count (ECC), anterior segment parameters, including anterior chamber depth (ACD) and anterior chamber angle (ACA) were measured before and 1mo after the laser posterior capsulotomy. In both groups, the BCVA improved significantly ( P <0.001 for the modified round pattern group, P =0.001 for the cruciate pattern group); the IOP and ECC did not significantly change. The ACD significantly decreased ( P <0.001 for both) and the ACA significantly increased ( P =0.001 for the modified round pattern group and P =0.034 for the cruciate group). The extent of changes in these parameters was not significantly different between the groups. Modified round pattern Nd:YAG laser posterior capsulotomy is an effective and safe method for the treatment of PCO. This method significantly changes the ACD and ACA, but the change in refraction is not significant. Modified round pattern Nd:YAG laser posterior capsulotomy can be considered a good alternative procedure in patients with symptomatic PCO.

Assessment of narrow angles by gonioscopy, Van Herick method and anterior segment optical coherence tomography.

PubMed

Park, Seong Bae; Sung, Kyung Rim; Kang, Sung Yung; Jo, Jung Woo; Lee, Kyoung Sub; Kook, Michael S

2011-07-01

To evaluate anterior chamber (AC) angles using gonioscopy, Van Herick technique and anterior segment optical coherence tomography (AS-OCT). One hundred forty-eight consecutive subjects were enrolled. The agreement between any two of three diagnostic methods, gonioscopy, AS-OCT and Van Herick, was calculated in narrow-angle patients. The area under receiver-operating characteristic curves (AUC) for discriminating between narrow and open angles determined by gonioscopy was calculated in all participants for AS-OCT parameter angle opening distance (AOD), angle recess area, trabecular iris surface area and anterior chamber depth (ACD). As a subgroup analysis, capability of AS-OCT parameters for detecting angle closure defined by AS-OCT was assessed in narrow-angle patients. The agreement between the Van Herick method and gonioscopy in detecting angle closure was excellent in narrow angles (κ = 0.80, temporal; κ = 0.82, nasal). However, agreement between gonioscopy and AS-OCT and between the Van Herick method and AS-OCT was poor (κ = 0.11-0.16). Discrimination capability of AS-OCT parameters between open and narrow angles determined by gonioscopy was excellent for all AS-OCT parameters (AUC, temporal: AOD500 = 0.96, nasal: AOD500 = 0.99). The AUCs for detecting angle closure defined by AS-OCT image in narrow angle subjects was good for all AS-OCT parameters (AUC, 0.80-0.94) except for ACD (temporal: ACD = 0.70, nasal: ACD = 0.63). Assessment of narrow angles by gonioscopy and the Van Herick technique showed good agreement, but both measurements revealed poor agreement with AS-OCT. The angle closure detection capability of AS-OCT parameters was excellent; however, it was slightly lower in ACD.

Utility of bleb imaging with anterior segment optical coherence tomography in clinical decision-making after trabeculectomy.

PubMed

Singh, Mandeep; Aung, Tin; Aquino, Maria C; Chew, Paul T K

2009-08-01

To determine if imaging of blebs with anterior segment optical coherence tomography (ASOCT) affects clinical decision-making with regard to laser suture lysis (LSL) after trabeculectomy. In this prospective observational case series, we included patients with poorly controlled intraocular pressure (IOP) after standardized trabeculectomy from May to November 2006. One observer assessed IOP, anterior chamber depth and bleb formation, and recorded a decision of whether or not to undertake LSL based on clinical grounds. A second observer masked to clinical data recorded a decision of whether or not to perform LSL based on ASOCT assessment of scleral flap position, presence of a sub-flap space, patency of the internal ostium, and bleb wall thickening. We compared the 2 observers' decisions to determine how ASOCT influenced decision-making. Seven eyes of 7 patients were included. On the basis of clinical examination, LSL was recommended in all 7 (100.0%) cases due to presence of elevated IOP, deep anterior chambers and poorly formed blebs. Using ASOCT, LSL was recommended in 5/7 (71.4%) cases with apposed scleral flaps, absent sub-flap spaces, and absent bleb wall thickening. In 2/7 (28.7%) cases, LSL was not recommended based on ASOCT findings of an elevated scleral flap, a patent sub-flap space, and bleb wall thickening. All 7 patients had good IOP control and formed blebs at a mean of 8.4+/-2.6 months after trabeculectomy, with a mean IOP of 14.3+/-3.2 mm Hg with no medications. This small study suggests that ASOCT imaging may affect decision-making with regard to LSL by providing information not apparent on clinical examination.

Phacoemulsification combined with posterior capsulorhexis and anterior vitrectomy in the management of malignant glaucoma in phakic eyes.

PubMed

Liu, Xing; Li, Mei; Cheng, Bing; Mao, Zhen; Zhong, Yimin; Wang, Dandan; Cao, Dan; Yu, Fenfen; Congdon, Nathan G

2013-11-01

  To describe sequential phacoemulsification-intraocular lens (IOL) implantation-posterior capsulorhexis-anterior vitrectomy in the management of phakic malignant glaucoma.   Twenty consecutive patients (25 eyes) with phakic malignant glaucoma were enrolled at the Zhongshan Ophthalmic Center, Sun Yat-sen University. All patients underwent phacoemulsification, IOL implantation and posterior capsulorhexis together with anterior vitrectomy via a clear corneal paracentesis. Visual acuity, intraocular pressure (IOP), anterior chamber depth (ACD), surgical complications and medications required after the surgery were recorded.   After surgery, the mean LogMAR visual acuity and ACD increased significantly (visual acuity from -1.56 ± 1.17 to -0.54 ± 0.81, p < 0.001; ACD from 0.367 ± 0.397 mm to 2.390 ± 0.575 mm, p < 0.001), and mean IOP decreased significantly (from 39.6 ± 10.6 mm Hg to 14.5 ± 4.1 mmHg, p < 0.001). No serious perioperative complications occurred, and only five eyes required topical glaucoma medications after surgery.   Combined phacoemulsification-IOL implantation-posterior capsulorhexis-anterior vitrectomy surgery is a safe and effective method for treating patients with phakic malignant glaucoma. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

Comparison of Scheimpflug imaging and spectral domain anterior segment optical coherence tomography for detection of narrow anterior chamber angles

PubMed Central

Grewal, D S; Brar, G S; Jain, R; Grewal, S P S

2011-01-01

Purpose To compare the performance of anterior chamber volume (ACV) and anterior chamber depth (ACD) obtained using Scheimpflug imaging with angle opening distance (AOD500) and trabecular-iris space area (TISA500) obtained using spectral domain anterior segment optical coherence tomography (SD-ASOCT) in detecting narrow angles classified using gonioscopy. Methods In this prospective, cross-sectional observational study, 265 eyes of 265 consecutive patients underwent sequential Scheimpflug imaging, SD-ASOCT imaging, and gonioscopy. Correlations between gonioscopy grading, ACV, ACD, AOD500, and TISA500 were evaluated. Area under receiver operating characteristic curve (AUC), sensitivity, specificity, and likelihood ratios (LRs) were calculated to assess the performance of ACV, ACD, AOD500, and TISA500 in detecting narrow angles (defined as Shaffer grade ≤1 in all quadrants). SD-ASOCT images were obtained at the nasal and temporal quadrants only. Results Twenty-eight eyes (10.6%) were classified as narrow angles on gonioscopy. ACV correlated with gonioscopy grading (P<0.001) for temporal (r=0.204), superior (r=0.251), nasal (r=0.213), and inferior (r=0.236) quadrants. ACV correlated with TISA500 for nasal (r=0.135, P=0.029) and temporal (P=0.160, P=0.009) quadrants and also with AOD500 for nasal (r=0.498, P<0.001) and temporal (r=0.517, P<0.001) quadrants. For detection of narrow angles, ACV (AUC=0.935; 95% confidence interval (CI) =0.898–0.961) performed similar to ACD (AUC=0.88, P=0.06) and significantly better than AOD500 nasal (AUC=0.761, P=0.001), AOD500 temporal (AUC=0.808, P<0.001), TISA500 nasal (AUC=0.756, P<0.001), and TISA500 temporal (AUC=0.738, P<0.001). Using a cutoff of 113 mm3, ACV had 90% sensitivity and 88% specificity for detecting narrow angles. Positive and negative LRs for ACV were 8.63 (95% CI=7.4–10.0) and 0.11 (95% CI=0.03–0.4), respectively. Conclusions ACV measurements using Scheimpflug imaging outperformed AOD500 and TISA500 using SD-ASOCT for detecting narrow angles. PMID:21336254

Agreement of Anterior Segment Parameters Obtained From Swept-Source Fourier-Domain and Time-Domain Anterior Segment Optical Coherence Tomography.

PubMed

Chansangpetch, Sunee; Nguyen, Anwell; Mora, Marta; Badr, Mai; He, Mingguang; Porco, Travis C; Lin, Shan C

2018-03-01

To assess the interdevice agreement between swept-source Fourier-domain and time-domain anterior segment optical coherence tomography (AS-OCT). Fifty-three eyes from 41 subjects underwent CASIA2 and Visante OCT imaging. One hundred eighty-degree axis images were measured with the built-in two-dimensional analysis software for the swept-source Fourier-domain AS-OCT (CASIA2) and a customized program for the time-domain AS-OCT (Visante OCT). In both devices, we examined the angle opening distance (AOD), trabecular iris space area (TISA), angle recess area (ARA), anterior chamber depth (ACD), anterior chamber width (ACW), and lens vault (LV). Bland-Altman plots and intraclass correlation (ICC) were performed. Orthogonal linear regression assessed any proportional bias. ICC showed strong correlation for LV (0.925) and ACD (0.992) and moderate agreement for ACW (0.801). ICC suggested good agreement for all angle parameters (0.771-0.878) except temporal AOD500 (0.743) and ARA750 (nasal 0.481; temporal 0.481). There was a proportional bias in nasal ARA750 (slope 2.44, 95% confidence interval [CI]: 1.95-3.18), temporal ARA750 (slope 2.57, 95% CI: 2.04-3.40), and nasal TISA500 (slope 1.30, 95% CI: 1.12-1.54). Bland-Altman plots demonstrated in all measured parameters a minimal mean difference between the two devices (-0.089 to 0.063); however, evidence of constant bias was found in nasal AOD250, nasal AOD500, nasal AOD750, nasal ARA750, temporal AOD500, temporal AOD750, temporal ARA750, and ACD. Among the parameters with constant biases, CASIA2 tends to give the larger numbers. Both devices had generally good agreement. However, there were proportional and constant biases in most angle parameters. Thus, it is not recommended that values be used interchangeably.

Radiation induced violations of blood circulation in the ciliary body and changes of the anterior chamber angle in the pathogenesis of glaucoma in clean up workers of the Chornobyl NPP accident and residents of contaminated areas.

PubMed

Garkava, N A; Fedirko, P A; Babenko, T F; Dorichevska, R E

2017-12-01

Estimate changes blood filling of the ciliary body and changes of the anterior chamber angle; study their influence to glaucoma pathogenesis in irradiated persons. Used the results of a randomly selected group survey of 41 clean up workers of the Chornobyl NPP accident (clean up workers), and 18 inhabitants of the zone of guaranteed voluntary resettlement; age at the time of the survey was 45-50 years. The control group consisted of 41 persons of the same age had not radiation exposure. State of the anterior chamber angle studied by gonioscopy, which was conducted 35 clean up workers and 35 persons of the control group. Changes of the blood circulation in the ciliary body examine by the ophtalmoreog raphy, what was done on 12 eyes of 6 clean up workers, control was 12 eyes of 6 persons had not radiation exposure. Detection revealed of the blood circulation in the ciliary body in all clean up workers, reography coefficient was probably lower (p < 0.05), than in the control group. The research of the state of the anterior chamber angle revealed a higher relative risk of appearance of involution changes of the anterior chamber angle in clean up work ers of ChNPP accident, in comparison with the control group was 3.5 (1.27; 9.5) χ2 = 7.48, p = 0.031. The same changes are characteristic for inhabitants of radiation polluted territories. Influence ionizing radiation causes a blood circulation decrease in the ciliary body and development changes of the angle of the anterior chamber. Presence of these changes can explain the features of the pathogene sis of glaucoma in irradiated late manifestation and, at the same time, severe course. N. A. Garkava, P. A. Fedirko, T. F. Babenko, R. E. Dorichevska.

Quantitative ionization chamber alignment to a water surface: Theory and simulation.

PubMed

Siebers, Jeffrey V; Ververs, James D; Tessier, Frédéric

2017-07-01

To examine the response properties of cylindrical cavity ionization chambers (ICs) in the depth-ionization buildup region so as to obtain a robust chamber-signal - based method for definitive water surface identification, hence absolute ionization chamber depth localization. An analytical model with simplistic physics and geometry is developed to explore the theoretical aspects of ionization chamber response near a phantom water surface. Monte Carlo simulations with full physics and ionization chamber geometry are utilized to extend the model's findings to realistic ion chambers in realistic beams and to study the effects of IC design parameters on the entrance dose response. Design parameters studied include full and simplified IC designs with varying central electrode thickness, wall thickness, and outer chamber radius. Piecewise continuous fits to the depth-ionization signal gradient are used to quantify potential deviation of the gradient discontinuity from the chamber outer radius. Exponential, power, and hyperbolic sine functional forms are used to model the gradient for chamber depths of zero to the depth of the gradient discontinuity. The depth-ionization gradient as a function of depth is maximized and discontinuous when a submerged IC's outer radius coincides with the water surface. We term this depth the gradient chamber alignment point (gCAP). The maximum deviation between the gCAP location and the chamber outer radius is 0.13 mm for a hypothetical 4 mm thick wall, 6.45 mm outer radius chamber using the power function fit, however, the chamber outer radius is within the 95% confidence interval of the gCAP determined by this fit. gCAP dependence on the chamber wall thickness is possible, but not at a clinically relevant level. The depth-ionization gradient has a discontinuity and is maximized when the outer-radius of a submerged IC coincides with the water surface. This feature can be used to auto-align ICs to the water surface at the time of scanning and/or be applied retrospectively to scan data to quantify absolute IC depth. Utilization of the gCAP should yield accurate and reproducible depth calibration for clinical depth-ionization measurements between setups and between users. © 2017 American Association of Physicists in Medicine.

SU-E-T-104: An Examination of Dose in the Buildup and Build-Down Regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tome, W; Kuo, H; Phillips, J

2015-06-15

Purpose: To examine dose in the buildup and build-down regions and compare measurements made with various models and dosimeters Methods: Dose was examined in a 30×30cm {sup 2} phantom of water-equivalent plastic with 10cm of backscatter for various field sizes. Examination was performed with radiochromic film and optically-stimulated-luminescent-dosimeter (OSLD) chips, and compared against a plane-parallel chamber with a correction factor applied to approximate the response of an extrapolation chamber. For the build-down region, a correction factor to account for table absorption and chamber orientation in the posterior-anterior direction was applied. The measurement depths used for the film were halfway throughmore » their sensitive volumes, and a polynomial best fit curve was used to determine the dose to their surfaces. This chamber was also compared with the dose expected in a clinical kernel-based computer model, and a clinical Boltzmann-transport-equation-based (BTE) computer model. The two models were also compared against each other for cases with air gaps in the buildup region. Results: Within 3mm, all dosimeters and models agreed with the chamber within 10% for all field sizes. At the entrance surface, film differed in comparison with the chamber from +90% to +15%, the BTE-model by +140 to +3%, and the kernel-based model by +20% to −25%, decreasing with increasing field size. At the exit surface, film differed in comparison with the chamber from −10% to −15%, the BTE-model by −53% to −50%, the kernel-based model by −55% to −57%, mostly independent of field size. Conclusion: The largest differences compared with the chamber were found at the surface for all field sizes. Differences decreased with increasing field size and increasing depth in phantom. Air gaps in the buildup region cause dose buildup to occur again post-gap, but the effect decreases with increasing phantom thickness prior to the gap.« less

Large variations in ocular dimensions in a multiethnic population with similar genetic background.

PubMed

Niu, Zhiqiang; Li, Jun; Zhong, Hua; Yuan, Zhonghua; Zhou, Hua; Zhang, Yang; Yuan, Yuansheng; Chen, Qin; Pan, Chen-Wei

2016-03-07

We aimed to describe the ethnic variations in ocular dimensions among three ethnic groups with similar genetic ancestry from mainland of China. We included 2119 ethnic Bai, 2202 ethnic Yi and 2183 ethnic Han adults aged 50 years or older in the study. Ocular dimensions including axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD) and lens thickness (LT) were measured using A-scan ultrasonography. Bai Chinese had longer ALs (P < 0.001), deeper ACDs (P < 0.001) but shallower VCDs (P < 0.001) compared with the other two ethnic groups. There were no ethnic variations in LTs. Diabetes was associated with shallower ACDs and this association was stronger in Bai Chinese compared with Yi or Han Chinese (P for interaction = 0.02). Thicker lenses were associated with younger age (P = 0.04), male gender (P < 0.001), smoking history (P = 0.01), alcohol intake (P = 0.03), the presence of cataract (P < 0.001), and the presence of diabetes (P < 0.001). There were significant differences in ocular dimensions among different ethnic groups with small differences in genetics but large variations in cultures and lifestyles.

Posterior corneal surface differences between non-laser in situ keratomileusis (LASIK) and 10-year post-LASIK myopic eyes.

PubMed

Dai, Ma-Li; Wang, Qin-Mei; Lin, Zu-Shun; Yu, Ye; Huang, Jin-Hai; Savini, Giacomo; Zhang, Jia; Wang, Ling; Xu, Chen-Chen

2018-03-01

To evaluate the posterior corneal surface differences between non-laser in situ keratomileusis (LASIK) and 10-year post-LASIK myopic eyes. The study included 130 eyes from 65 patients, who were treated with myopic LASIK 10 years ago. In addition, 130 eyes from 65 unoperated myopic patients of matching present age and preoperative refraction were divided into control group. Data on the posterior corneal surface and anterior chamber were obtained from Pentacam software and compared between the groups. Postoperative visual acuity (VA) and refractive error were also analysed. The mean preoperative spherical equivalent (SE) was -6.99 ± 1.78 dioptre (D) in the LASIK group. Ten years after surgery, the mean SE was -0.45 ± 1.22 D, the efficacy index was 0.98, and the safety index was 1.01. The posterior corneal elevations of the LASIK group at 2 mm corneal diameter were significantly lower than those of the control group. However, posterior corneal elevations at 6 mm corneal diameter were higher in the LASIK group than the controls (p < 0.01 for all). The mean Q-values of posterior corneal surface demonstrated significant positive direction compared to that of control eyes at 6 and 7 mm corneal diameters (p < 0.05 for both). At the thinnest point of the cornea, the anterior chamber depths were shallower in the LASIK group than in controls. Meanwhile, the anterior chamber volumes (ACV) were smaller in the LASIK group than in the control group. Our results demonstrated that the posterior corneal surface tends to show signs of central flattening and peripheral steepening 10 years after myopic LASIK surgery compared to that of non-operated myopic eyes. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Angle stability and outflow in dual blade ab interno trabeculectomy with active versus passive chamber management

PubMed Central

Wang, Chao; Dang, Yalong; Waxman, Susannah; Xia, Xiaobo; Weinreb, Robert N.

2017-01-01

Purpose To compare intraoperative angle stability and postoperative outflow of two ab interno trabeculectomy devices that excise the trabecular meshwork with or without active aspiration and irrigation. We hypothesized that anterior segment optical coherence tomography (AS-OCT) allows for a quantitative comparison of intraoperative angle stability in a microincisional glaucoma surgery (MIGS) pig eye training model. Methods Twelve freshly enucleated porcine eyes were measured with AS-OCT at baseline, at the beginning of the procedure and at its conclusion to determine the anterior chamber depth (ACD) and the nasal angle α in degrees. The right and left eye of pairs were randomly assigned to an active dual blade goniectome (aDBG) and a passive dual blade goniectome (pDBG) group, respectively. The aDBG had irrigation and aspiration ports while the pDBG required surgery under viscoelastic. We performed the procedures using our MIGS training system with a standard, motorized ophthalmic operating microscope. We estimated outflow by obtaining canalograms with fluorescent spheres. Results In aDBG, the nasal angle remained wide open during the procedure at above 90° and did not change towards the end (100±10%, p = 0.9). In contrast, in pDBG, ACD decreased by 51±19% to 21% below baseline (p<0.01) while the angle progressively narrowed by 40±12% (p<0.001). Canalograms showed a similar extent of access to the outflow tract with the aDBG and the pDBG (p = 0.513). The average increase for the aDBG in the superonasal and inferonasal quadrants was between 27 to 31% and for the pDBG between 15 to 18%. Conclusion AS-OCT demonstrated that active irrigation and aspiration improved anterior chamber maintenance and ease of handling with the aDBG in this MIGS training model. The immediate postoperative outflow was equally good with both devices. PMID:28486513

Comparative study of induced changes in effective lens position and refraction after Nd:YAG laser capsulotomy according to intraocular lens design.

PubMed

Monteiro, Tiago; Soares, Andreia; Leite, Ricardo Dourado; Franqueira, Nuno; Faria-Correia, Fernando; Vaz, Fernando

2018-01-01

To evaluate and compare the changes in refraction and effective intraocular lens (IOL) position between a plate-haptic IOL and a c-loop single-piece IOL after neodymium-doped yttrium aluminium garnet (YAG) laser posterior capsulotomy. In a prospective study, anterior chamber depth and subjective refraction were measured in 110 pseudophakic eyes from 110 patients, before and 1 month after YAG laser capsulotomy. Patients were divided into 2 groups according to the IOL design: group 1 (plate-haptic acrylic hydrophilic AT LISA tri 839MP ® ) and group 2 (c-loop acrylic hydrophobic single-piece AcrySof ® SA60AT). Lens position was obtained through optical coherence biometry (Biograph WaveLight OB820 ® ). YAG laser capsulotomy was performed 37.8±9.8 months after surgery in group 1 and 40.6±8.6 months in group 2 ( p =0.125). Significant changes were found in the lens effective position after treatment in the 2 groups. The YAG posterior capsulotomy led to a change of anterior chamber depth in group 1 from 4.03±0.32 mm to 3.86±0.34 mm ( p =0.02) and in group 2 from 4.03±0.37 mm to 4.14±0.45 mm ( p =0.025). After YAG laser posterior capsulotomy, no significant changes were observed in mean spherical equivalent, sphere or cylinder for both groups ( p >0.05). YAG laser posterior capsulotomy can induce a significant change in the IOL position according to the IOL type; however, the refractive change after treatment is clinically insignificant.

Morphometric assessment of normal human ciliary body using ultrasound biomicroscopy.

PubMed

Okamoto, Yoshifumi; Okamoto, Fumiki; Nakano, Shinichiro; Oshika, Tetsuro

2017-12-01

To quantitatively assess the biometry of the ciliary body in normal human eyes using ultrasound biomicroscopy. We evaluated 85 eyes of 85 normal subjects (35 men and 50 women), whose age ranged from 11 to 86 years (mean ± SD, 56.8 ± 20.4 years). The eyes were assessed along the 3-, 6-, 9-, and 12-o'clock meridians relative to the center of the cornea. Clinical data were collected, including age, axial length, ciliary body length (CBL), ciliary body thickness (CBT), anterior chamber depth, iris root thickness, trabecular-iris angle, and scleral-ciliary process angle. Axial length was measured using A-scan ultrasonography. CBL and CBT tended to be larger in the superior than in the inferior quadrant, but the differences among the four quadrants were not statistically significant. The average CBL showed a significant positive correlation with the average CBT (r = 0.40, P < 0.001). Average CBL and CBT were significantly correlated with axial length (r = 0.33, P = 0.031; r = 0.46, P < 0.01 respectively). In addition, the average CBL was significantly correlated with anterior chamber depth (r = 0.23, P < 0.05), trabecular-iris angle (r = 0.29, P = 0.01), and scleral-ciliary process angle (r = 0.40, P < 0.001). Ultrasound biomicroscopic imaging demonstrated that the ciliary body is similar in size in all circumferences, and eyes with longer axial length have an elongated and thicker ciliary body. The values obtained in the present study may serve as standard clinical references.

Comparative study of induced changes in effective lens position and refraction after Nd:YAG laser capsulotomy according to intraocular lens design

PubMed Central

Monteiro, Tiago; Soares, Andreia; Leite, Ricardo Dourado; Franqueira, Nuno; Faria-Correia, Fernando; Vaz, Fernando

2018-01-01

Purpose To evaluate and compare the changes in refraction and effective intraocular lens (IOL) position between a plate-haptic IOL and a c-loop single-piece IOL after neodymium-doped yttrium aluminium garnet (YAG) laser posterior capsulotomy. Methods In a prospective study, anterior chamber depth and subjective refraction were measured in 110 pseudophakic eyes from 110 patients, before and 1 month after YAG laser capsulotomy. Patients were divided into 2 groups according to the IOL design: group 1 (plate-haptic acrylic hydrophilic AT LISA tri 839MP®) and group 2 (c-loop acrylic hydrophobic single-piece AcrySof® SA60AT). Lens position was obtained through optical coherence biometry (Biograph WaveLight OB820®). Results YAG laser capsulotomy was performed 37.8±9.8 months after surgery in group 1 and 40.6±8.6 months in group 2 (p=0.125). Significant changes were found in the lens effective position after treatment in the 2 groups. The YAG posterior capsulotomy led to a change of anterior chamber depth in group 1 from 4.03±0.32 mm to 3.86±0.34 mm (p=0.02) and in group 2 from 4.03±0.37 mm to 4.14±0.45 mm (p=0.025). After YAG laser posterior capsulotomy, no significant changes were observed in mean spherical equivalent, sphere or cylinder for both groups (p>0.05). Conclusion YAG laser posterior capsulotomy can induce a significant change in the IOL position according to the IOL type; however, the refractive change after treatment is clinically insignificant. PMID:29593378

Comparison of axial length, anterior chamber depth and intraocular lens power between IOLMaster and ultrasound in normal, long and short eyes.

PubMed

Dong, Jing; Zhang, Yaqin; Zhang, Haining; Jia, Zhijie; Zhang, Suhua; Wang, Xiaogang

2018-01-01

To compare the axial length (AL), anterior chamber depth (ACD) and intraocular lens power (IOLP) of IOLMaster and Ultrasound in normal, long and short eyes. Seventy-four normal eyes (≥ 22 mm and ≤ 25 mm), 74 long eyes (> 25 mm) and 78 short eyes (< 22 mm) underwent AL and ACD measurements with both devices in the order of IOLMaster followed by Ultrasound. The IOLP were calculated using a free online LADAS IOL formula calculator. The difference in AL and IOLP between IOLMaster and Ultrasound was statistically significant when all three groups were combined. The difference in ACD between IOLMaster and Ultrasound was statistically significant in the normal group (P<0.001) and short eye group (P<0.001) but not the long eye group (P = 0.465). For the IOLP difference between IOLMaster and Ultrasound in the normal group, the percentage of IOLP differences <|0.5|D, ≥|0.5|D<|0.75|D, ≥|0.75|D<|1.0|D, and ≥|1.0|D were 90.5%, 8.1%, 1.4% and 0%, respectively. For the long eye group, they were 90.5%, 5.4%, 4.1% and 0%, respectively. For the short eye group, they were 61.5%, 23.1%, 10.3%, and 5.1%, respectively. IOLMaster and Ultrasound have statistically significant differences in AL measurements and IOLP (using LADAS formula) for normal, long eye and short eye. The two instruments agree regarding ACD measurements for the long eye group, but differ for the normal and short eye groups. Moreover, the high percentage of IOLP differences greater than |0.5|D in the short eye group is noteworthy.

Refractive Outcomes of Three-Port Lens-Sparing Vitrectomy for Retinopathy of Prematurity (An AOS Thesis)

PubMed Central

Holz, Eric R.

2009-01-01

Purpose: To study the refractive outcomes of 3-port lens-sparing vitrectomy (LSV) for subtotal retinal detachments due to retinopathy of prematurity (ROP). Lens-sparing vitrectomy may provide superior refractive outcomes by limiting induced myopia of prematurity. Methods: This is a retrospective, consecutive, nonrandomized, comparative (paired eye) study. Entrance criteria were previous complete ablative laser for threshold ROP in both eyes, followed by LSV in one eye for stage 4A traction retinal detachment. Both eyes then maintained complete retinal attachment. Main outcome variables were cycloplegic refraction, keratometry, and biometric values for axial length, lens thickness, and anterior chamber depth. Results: Nine patients met inclusion criteria. Lens-sparing vitrectomy eyes were significantly less myopic than control eyes (−6.78 D vs −10.33 D, P < .005). The reduction in myopia in LSV eyes was predominantly due to increased anterior chamber depth (3.81 mm ± 0.217 vs 2.96 mm ± 0.232, P < .005). There was a minor contribution from reduced corneal power in LSV eyes (43.89 D ± 0.253 vs 44.20 D ± 0.265, P < .005). There was a minor negative impact from increased lens thickness in LSV eyes (3.85 ± 0.32 mm vs 3.74 ± 0.31, P < .005). There was no significant difference in axial length or lens power between the LSV and control groups. Conclusions: The data demonstrate that infant eyes undergoing 3-port LSV for stage 4A ROP develop less myopia than fellow eyes treated with laser alone. The difference is due to posterior displacement of the lens-iris diaphragm with a smaller contribution from reduced corneal power. The reduction in myopia may improve functional outcomes following 3-port LSV for stage 4A ROP. PMID:20126504

Comparative Efficacy of the New Optical Biometer on Intraocular Lens Power Calculation (AL-Scan versus IOLMaster).

PubMed

Ha, Ahnul; Wee, Won Ryang; Kim, Mee Kum

2018-05-15

To evaluate the agreement in axial length (AL), keratometry, and anterior chamber depth measurements between AL-Scan and IOLMaster biometers and to compare the efficacy of the AL-Scan on intraocular lens (IOL) power calculations and refractive outcomes with those obtained by the IOLMaster. Medical records of 48 eyes from 48 patients who underwent uneventful phacoemulsification and IOL insertion were retrospectively reviewed. One of the two types of monofocal aspheric IOLs were implanted (Tecnis ZCB00 [Tecnis, n = 34] or CT Asphina 509M [Asphina, n = 14]). Two different partial coherence interferometers measured and compared AL, keratometry (2.4 mm), anterior chamber depth, and IOL power calculations with SRK/T, Hoffer Q, Holladay2, and Haigis formulas. The difference between expected and actual final refractive error was compared as refractive mean error (ME), refractive mean absolute error (MAE), and median absolute error (MedAE). AL measured by the AL-Scan was shorter than that measured by the IOLMaster (p = 0.029). The IOL power of Tecnis did not differ between the four formulas; however, the Asphina measurement calculated using Hoffer Q for the AL-Scan was lower (0.28 diopters, p = 0.015) than that calculated by the IOLMaster. There were no statistically significant differences between the calculations by MAE and MedAE for the four formulas in either IOL. In SRK/T, ME in Tecnis-inserted eyes measured by AL-Scan showed a tendency toward myopia (p = 0.032). Measurement by AL-Scan provides reliable biometry data and power calculations compared to the IOLMaster; however, refractive outcomes of Tecnis-inserted eyes by AL-Scan calculated using SRK/T can show a slight myopic tendency. © 2018 The Korean Ophthalmological Society.

[The effects of glycemic control on ophthalmic refraction in diabetic patients].

PubMed

Li, Hai-yan; Luo, Guo-chun; Guo, Jiang; Liang, Zhen

2010-10-01

To evaluate effects of glycemic control on refraction in diabetic patients. Twenty newly diagnosed diabetic patients were included in this study. The random blood glucose, glycosylated hemoglobin A1c (HbA1c) levels, fasting C-peptide and postprandial 2 h C-peptide levels were measured before treatment. The patients with random blood glucose ≥ 12.0 mmol/L and HbA1c ≥ 10.0% were selected. Refraction, intraocular pressure, radius of the anterior corneal curvature, depth of the anterior chamber, lens thickness, vitreous length, and axial length were measured on admission and at the end of week 1, 2, 3 and 4 during glycaemic control. A transient hyperopic change occurred in all the patients receiving glycemic control with a mean maximum hyperopic changes of 1.6 D (0.50 D ∼ 3.20 D). There was a positive correlation between the magnitude of the maximum hyperopic changes and the HbA1c levels on admission (r = 0.84, P < 0.05). There was a positive correlation between the magnitude of the maximum hyperopic changes and the daily rate of blood glucose reduction over the first 7 days of the treatment (r = 0.53, P < 0.05). There was no significant correlation between the magnitude of the maximum hyperopic changes and the levels of random blood glucose on admission. No significant correlation was observed between the maximum hyperopic changes and fasting C-peptide or postprandial 2 h C-peptide. There were no significant correlations between the magnitude of the maximum hyperopic changes and age, blood press, body mass index, triglyceride, total cholesterol, low-density lipoprotein or high-density lipoprotein. No significant changes were observed in the intraocular pressure, radius of the anterior corneal curvature, depth of the anterior chamber, lens thickness, vitreous length and axial length during glycemic control. Transient hyperopic changes occur after glycemic control in diabetic patients with severe hyperglycaemia. The degrees of transient hyperopia are highly dependent on HbA1c levels before treatment and the rate of reduction of glucose level over the first 7 days of treatment. This is probably due to the decrease of refractive power by lens hydration, not morphological change of lens.

A Rare Presentation of Cyclitis Induced Myopia.

PubMed

Ijaz, Umar; Habib, Asad; Rathore, Hassan Sajjad

2018-03-01

Unilateral cyclitis leading to myopia is a rare and clinical relevant entity. In clinical settings, pseudomyopia is generally encountered in the form of accommodative spasm, which is always bilateral. Cyclitis due to inflammation, on the other hand, can cause pseudomyopia unilaterally and it is a very rare presentation. A young male with acute anterior uveitis, presented with acute episode of unilateral myopia. When patient was examined on first visit, there were no cells in anterior chamber; so he was started on cycloplegic eye drops, but his condition didn't improve. Examination on subsequent visit revealed cellular reaction in anterior chamber and narrowing of anterior chamber angles on anterior segment optical coherence tomography (OCT). Treatment for uveitis was started and patient's visual acuity and refractive error improved. Pseudomyopia is a known complication of several drugs and certain medical conditions. The possible mechanism is supraciliary exudation causing relaxation of zonular fibers and increased convexity of the crystalline lens. Myopia in the setting of a mild cellular reaction can easily be missed and has not been reported yet to the best of authors' literature search.

Intraocular concentrations of gatifloxacin and moxifloxacin in the anterior chamber via diffusion through the cornea using collagen shields.

PubMed

Kleinmann, Guy; Larson, Scott; Neuhann, Irmingard M; Hunold, Anne C; LeBoyer, Russell; Hickman, Scott; Mamalis, Nick; Olson, Randall J

2006-02-01

To evaluate the penetration of gatifloxacin and moxifloxacin into the anterior chamber, and any adverse reaction to the cornea, using collagen shields presoaked in oversaturated solutions of the antibiotics. Collagen shields, presoaked for 10 minutes in an oversaturated solution of gatifloxacin or moxifloxacin, were placed on the surface of each of the corneas of 15 rabbits for a total of 30 eyes (15 in each group). The antibiotics were prepared by dissolving the powder form of the antibiotics in a solution until no further particulate could be further dissolved. Aqueous humor samples were taken 3.5 and 6 hours later. The initial concentrations of gatifloxacin and moxifloxacin were 5.43 +/- 0.16 mg/mL and 3.14 +/- 0.22 mg/mL, respectively. The average concentration of gatifloxacin in the anterior chamber was higher than that of moxifloxacin at the 3.5-hour sample (6.32 +/- 2.67 microg/mL versus 3.55 +/- 3.5 microg/mL, P = 0.0034). The concentrations of both antibiotics, although decreased, remained relatively high at the 6-hour sample (1.39 +/- 1.13 microg/mL versus 0.816 +/- 0.6 microg/mL at 6 hours, respectively, P = 0.22). No obvious clinical or histologic signs of toxicity were noticed in either group. Gatifloxacin and moxifloxacin showed good penetration into the anterior chamber with no obvious adverse reaction to the cornea. The concentrations in the anterior chamber exceeded the minimal inhibitory concentration (MIC) 90 of most organisms responsible for postoperative endophthalmitis (POE).

Responses of the Ocular Anterior Segment and Refraction to 0.5% Tropicamide in Chinese School-Aged Children of Myopia, Emmetropia, and Hyperopia.

PubMed

Yuan, Ying; Zhang, Zhengwei; Zhu, Jianfeng; He, Xiangui; Du, Ergang; Jiang, Kelimu; Zheng, Wenjing; Ke, Bilian

2015-01-01

Purpose. To investigate the changes of anterior segment after cycloplegia and estimate the association of such changes with the changes of refraction in Chinese school-aged children of myopia, emmetropia, and hyperopia. Methods. 309 children were recruited and eligible subjects were assigned to three groups: hyperopia, emmetropia, or myopia. Cycloplegia was achieved with five cycles of 0.5% tropicamide. The Pentacam system was used to measure the parameters of interest before and after cycloplegia. Results. In the myopic group, the lenses were thinner and the lens position was significantly more posterior than that of the emmetropic and hyperopic groups in the cycloplegic status. The correlations between refraction and lens thickness (age adjusted; r = 0.26, P < 0.01), and lens position (age adjusted; r = -0.31, P < 0.01) were found. After cycloplegia, ACD and ACV significantly increased, while ACA significantly decreased. Changes in refraction, ACD, ACV, and ACA were significantly different among the three groups (P < 0.05, all). Changes of refraction were correlated with changes of ACD (r = 0.41, P < 0.01). Conclusions. Myopia presented thinner lenses and smaller changes of anterior segment and refraction after cycloplegia when compared to emmetropia and hyperopia. Changes of anterior chamber depth were correlated with refraction changes. This may contribute to a better understanding of the relationship between anterior segment and myopia.

Determination of relative ion chamber calibration coefficients from depth-ionization measurements in clinical electron beams

NASA Astrophysics Data System (ADS)

Muir, B. R.; McEwen, M. R.; Rogers, D. W. O.

2014-10-01

A method is presented to obtain ion chamber calibration coefficients relative to secondary standard reference chambers in electron beams using depth-ionization measurements. Results are obtained as a function of depth and average electron energy at depth in 4, 8, 12 and 18 MeV electron beams from the NRC Elekta Precise linac. The PTW Roos, Scanditronix NACP-02, PTW Advanced Markus and NE 2571 ion chambers are investigated. The challenges and limitations of the method are discussed. The proposed method produces useful data at shallow depths. At depths past the reference depth, small shifts in positioning or drifts in the incident beam energy affect the results, thereby providing a built-in test of incident electron energy drifts and/or chamber set-up. Polarity corrections for ion chambers as a function of average electron energy at depth agree with literature data. The proposed method produces results consistent with those obtained using the conventional calibration procedure while gaining much more information about the behavior of the ion chamber with similar data acquisition time. Measurement uncertainties in calibration coefficients obtained with this method are estimated to be less than 0.5%. These results open up the possibility of using depth-ionization measurements to yield chamber ratios which may be suitable for primary standards-level dissemination.

Iris as a reflector for differential absorption low-coherence interferometry to measure glucose level in the anterior chamber

PubMed Central

Zhou, Yong; Zeng, Nan; Ji, Yanhong; Li, Yao; Dai, Xiangsong; Li, Peng; Duan, Lian; Ma, Hui; He, Yonghong

2011-01-01

We present a method of glucose concentration detection in the anterior chamber with a differential absorption optical low-coherent interferometry (LCI) technique. Back-reflected light from the iris, passing through the anterior chamber twice, was selectively obtained with the LCI technique. Two light sources, one centered within (1625 nm) and the other centered outside (1310 nm) of a glucose absorption band were used for differential absorption measurement. In the eye model and pig eye experiments, we obtained a resolution glucose level of 26.8 mg/dL and 69.6 mg/dL, respectively. This method has a potential application for noninvasive detection of glucose concentration in aqueous humor, which is related to the glucose concentration in blood. PMID:21280906

Corneal toxicity after Ozurdex(®) migration into anterior chamber.

PubMed

Bernal, L; Estévez, B

2016-06-01

To describe a case of corneal toxicity after migration of a dexamethasone implant into the anterior chamber. A 62-year-old man with aphakia and a history of vitrectomy received a dexamethasone implant for a refractory Irvine-Gass syndrome. Thirty days later, the implant migrated into the anterior chamber causing endothelial contact with secondary corneal oedema that justified the removal of the implant without resolution of the oedema. Clinical tolerability to dislocated implant is poor in cases with pre-existing corneal oedema, and because of this, it must be removed early. In cases of aphakia and vitrectomy, the increased risk of Ozurdex(®) dislocation justifies performing a prior endothelial count. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Anterior chamber configuration in patients with glaucoma: MR gonioscopy evaluation with half-Fourier single-shot RARE sequence and microscopy coil.

PubMed

Tanitame, Keizo; Sasaki, Ko; Sone, Takashi; Uyama, Shinji; Sumida, Masumi; Ichiki, Toshio; Ito, Katsuhide

2008-10-01

The purpose of the study was to determine the accuracy of half-Fourier single-shot rapid acquisition with relaxation enhancement high-spatial-resolution magnetic resonance (MR) imaging performed with a microscopy coil in the diagnosis of narrow anterior chamber angle in patients with glaucoma. Slit-lamp biomicroscopy served as the reference standard. The institutional review board approved this study, and written informed consent was obtained from the 20 recruited patients. There was excellent agreement between MR gonioscopy and slit-lamp biomicroscopy in the classification of anterior chamber angles as narrow or open (kappa = 0.89 [95% confidence interval: 0.69, 1.10]). MR gonioscopy has substantial potential as a technique used to evaluate glaucoma. (c) RSNA, 2008.

Objective measurement of accommodative biometric changes using ultrasound biomicroscopy

PubMed Central

Ramasubramanian, Viswanathan; Glasser, Adrian

2015-01-01

PURPOSE To demonstrate that ultrasound biomicroscopy (UBM) can be used for objective quantitative measurements of anterior segment accommodative changes. SETTING College of Optometry, University of Houston, Houston, Texas, USA. DESIGN Prospective cross-sectional study. METHODS Anterior segment biometric changes in response to 0 to 6.0 diopters (D) of accommodative stimuli in 1.0 D steps were measured in eyes of human subjects aged 21 to 36 years. Imaging was performed in the left eye using a 35 MHz UBM (Vumax) and an A-scan ultrasound (A-5500) while the right eye viewed the accommodative stimuli. An automated Matlab image-analysis program was developed to measure the biometry parameters from the UBM images. RESULTS The UBM-measured accommodative changes in anterior chamber depth (ACD), lens thickness, anterior lens radius of curvature, posterior lens radius of curvature, and anterior segment length were statistically significantly (P < .0001) linearly correlated with accommodative stimulus amplitudes. Standard deviations of the UBM-measured parameters were independent of the accommodative stimulus demands (ACD 0.0176 mm, lens thickness 0.0294 mm, anterior lens radius of curvature 0.3350 mm, posterior lens radius of curvature 0.1580 mm, and anterior segment length 0.0340 mm). The mean difference between the A-scan and UBM measurements was −0.070 mm for ACD and 0.166 mm for lens thickness. CONCLUSIONS Accommodating phakic eyes imaged using UBM allowed visualization of the accommodative response, and automated image analysis of the UBM images allowed reliable, objective, quantitative measurements of the accommodative intraocular biometric changes. PMID:25804579

A method of measuring anterior chamber volume using the anterior segment optical coherence tomographer and specialized software.

PubMed

Wang, Ningli; Wang, Bingsong; Zhai, Gaoshou; Lei, Kun; Wang, Lan; Congdon, Nathan

2007-05-01

To describe and evaluate a new method for measuring anterior chamber volume (ACV). Observational case series. The authors measured ACV using the anterior chamber (AC) optical coherence tomographer (OCT) and applied image-processing software developed by them. Repeatability was evaluated. The ACV was measured in patient groups with normal ACs, shallow ACs, and deep ACs. The volume difference before and after laser peripheral iridotomy (LPI) was analyzed for the shallow and deep groups. Coefficients of repeatability for intraoperator, interoperator, and interimage measurements were 0.406%, 0.958%, and 0.851%, respectively. The limits of agreement for intraoperator and interoperator measurement were -0.911 microl to 1.343 microl and -7.875 microl to -2.463 microl, respectively. There were significant ACV differences in normal, shallow, and deep AC eyes (P < .001) and before and after LPI in shallow AC (P < .001) and deep AC (P = .008) eyes. The ACV values obtained by this method were repeatable and in accord with clinical observation.

Two-year changes in refractive error and related biometric factors in an adult Chinese population.

PubMed

He, Mingguang; Kong, Xiangbin; Chen, Qianyun; Zeng, Yangfa; Huang, Yuanzhou; Zhang, Jian; Morgan, Ian G; Meltzer, Mirjam E; Jin, Ling; Congdon, Nathan

2014-08-01

This article provides, to our knowledge, the first longitudinal population-based data on refractive error (RE) in Chinese persons. To study cohort effects and changes associated with aging in REs among Chinese adults. A 2-year, longitudinal population-based cohort study was conducted in southern China. Participants, identified using cluster random sampling, included residents of Yuexiu District, Guangzhou, China, aged 35 years or older who had undergone no previous eye surgery. Participants underwent noncycloplegic automated refraction and keratometry in December 2008 and December 2010; in a random 50% sample of the participants, anterior segment ocular coherence tomography measurement of lens thickness, as well as measurement of axial length and anterior chamber depth by partial coherence laser interferometry, were performed. Two-year change in spherical equivalent refraction (RE), lens thickness, axial length, and anterior chamber depth in the right eye. A total of 745 individuals underwent biometric testing in both 2008 and 2010 (2008 mean [SD] age, 52.2 [11.5] years; 53.7% women). Mean RE showed a 2-year hyperopic shift from -0.44 (2.21) to -0.31 (2.26) diopters (D) (difference, +0.13; 95% CI, 0.11 to 0.16). A consistent 2-year hyperopic shift of 0.09 to 0.22 D was observed among participants aged 35 to 64 years when stratifying by decade, suggesting that a substantial change in RE with aging may occur during this 30-year period. Cross-sectionally, RE increased only in the cohort younger than 50 years (0.11 D/y; 95% CI, 0.06 to 0.16). In the cross-sectional data, axial length decreased at -0.06 mm/y (95% CI, -0.09 to -0.04), although the 2-year change in axial length was positive and thus could not explain the cross-sectional difference. These latter results suggest a cohort effect, with greater myopia developing among younger persons. This first Chinese population-based longitudinal study of RE provides evidence for both important longitudinal aging changes and cohort effects, most notably greater myopia prevalence among younger persons.

On the wall perturbation correction for a parallel-plate NACP-02 chamber in clinical electron beams.

PubMed

Zink, K; Wulff, J

2011-02-01

In recent years, several Monte Carlo studies have been published concerning the perturbation corrections of a parallel-plate chamber in clinical electron beams. In these studies, a strong depth dependence of the relevant correction factors (p(wall) and P(cav)) for depth beyond the reference depth is recognized and it has been shown that the variation with depth is sensitive to the choice of the chamber's effective point of measurement. Recommendations concerning the positioning of parallel-plate ionization chambers in clinical electron beams are not the same for all current dosimetry protocols. The IAEA TRS-398 as well as the IPEM protocol and the German protocol DIN 6800-2 interpret the depth of measurement within the phantom as the water equivalent depth, i.e., the nonwater equivalence of the entrance window has to be accounted for by shifting the chamber by an amount deltaz. This positioning should ensure that the primary electrons traveling from the surface of the water phantom through the entrance window to the chamber's reference point sustain the same energy loss as the primary electrons in the undisturbed phantom. The objective of the present study is the determination of the shift deltaz for a NACP-02 chamber and the calculation of the resulting wall perturbation correction as a function of depth. Moreover, the contributions of the different chamber walls to the wall perturbation correction are identified. The dose and fluence within the NACP-02 chamber and a wall-less air cavity is calculated using the Monte Carlo code EGSnrc in a water phantom at different depths for different clinical electron beams. In order to determine the necessary shift to account for the nonwater equivalence of the entrance window, the chamber is shifted in steps deltaz around the depth of measurement. The optimal shift deltaz is determined from a comparison of the spectral fluence within the chamber and the bare cavity. The wall perturbation correction is calculated as the ratio between doses for the complete chamber and a wall-less air cavity. The high energy part of the fluence spectra within the chamber strongly varies even with small chamber shifts, allowing the determination of deltaz within micrometers. For the NACP-02 chamber a shift deltaz = -0.058 cm results. This value is independent of the energy of the primary electrons as well as of the depth within the phantom and it is in good agreement with the value recommended in the German dosimetry protocol. Applying this shift, the calculated wall perturbation correction as a function of depth is varying less than 1% from zero up to the half value depth R50 for electron energies in the range of 6-21 MeV. The remaining depth dependence can mainly be attributed to the scatter properties of the entrance window. When neglecting the nonwater equivalence of the entrance window, the variation of p(wall) with depth is up to 10% and more, especially for low electron energies. The variation of the wall perturbation correction for the NACP-02 chamber in clinical electron beams strongly depends on the positioning of the chamber. Applying a shift deltaz = -0.058 cm toward the focus ensures that the primary electron spectrum within the chamber bears the largest resemblance to the fluence of a wall-less cavity. Hence, the influence of the chamber walls on the perturbation correction can be separated out and the residual variation of p(wall) with depth is minimized.

Femtosecond laser–assisted cataract surgery in vitrectomized eye with posterior chamber phakic intraocular lens

PubMed Central

Anisimova, Natalia; Malyugin, Boris; Arbisser, Lisa B.; Sobolev, Nikolay

2017-01-01

Summary We describe a case of femtosecond laser–assisted cataract surgery (FLACS) in an eye with multiple comorbidities, including retinal detachment surgery, high myopia, posterior chamber phakic intraocular lens (PC pIOL) and residual, emulsified, silicone oil located in the anterior chamber. FLACS was affected by the optical blockage, but the incomplete capsular tear was recoverable. The case suggests that silicone oil bubbles concentrated at the dome of the posterior corneal surface, along with the PC pIOL optic edges and scars after corneal astigmatic relaxing incisions can lead to incomplete anterior capsulotomy. PMID:28924422

High prevalence of narrow angles among Filipino-American patients.

PubMed

Seider, Michael I; Sáles, Christopher S; Lee, Roland Y; Agadzi, Anthony K; Porco, Travis C; Weinreb, Robert N; Lin, Shan C

2011-03-01

To determine the prevalence of gonioscopically narrow anterior chamber angles in a Filipino-American clinic population. The records of 122 consecutive, new, self-declared Filipino-American patients examined in a comprehensive ophthalmology clinic in Vallejo, California were reviewed retrospectively. After exclusion, 222 eyes from 112 patients remained for analysis. Data were collected for anterior chamber angle grade as determined by gonioscopy (Shaffer system), age, sex, manifest refraction (spherical equivalent), intraocular pressure, and cup-to-disk ratio. Data from both eyes of patients were included and modeled using standard linear mixed-effects regression. As a comparison, data were also collected from a group of 30 consecutive White patients from the same clinic. After exclusion, 50 eyes from 25 White patients remained for comparison. At least 1 eye of 24% of Filipino-American patients had a narrow anterior chamber angle (Shaffer grade ≤ 2). Filipino-American angle grade significantly decreased with increasingly hyperopic refraction (P=0.007) and larger cup-to-disk ratio (P=0.038). Filipino-American women had significantly decreased angle grades compared with men (P=0.028), but angle grade did not vary by intraocular pressure or age (all, P≥ 0.059). Narrow anterior chamber angles are highly prevalent in Filipino-American patients in our clinic population.

Design of a novel system for spectroscopy measurements of the aqueous humor

NASA Astrophysics Data System (ADS)

Miller, Joe; Uttamchandani, Deepak G.

2001-06-01

The authors report on the design of a system which will enable real time measurements of (therapeutic) drug concentrations in the anterior chamber of the eye. Currently the concentration of therapeutic drugs in the anterior chamber is determined by analyzing samples which have been removed from the aqueous humor of laboratory animal eyes. This sampling via paracentesis can be painful and does not provide a continuous measurement. Our system will be far less invasive, removing the need for sampling via paracentesis, and also providing a continuous measurement, enabling a more complete understanding of the kinetics of ophthalmic drugs. A key component in our novel system is a specially constructed contact lens. We report on the design, optimization and manufacture of such a contact lens system capable of directing UV/VIS light in, across and out of the anterior chamber of the eye, thereby enabling absorption spectroscopy measurements of the aqueous humor to be undertaken. Design of the one piece contact lens/mirror system was achieved using the Zemax optical design software package and the lens was fabricated from synthetic fused silica. Results from modeling of the lens and experimental measurements on light propagation across the anterior chamber of animal eyes assisted by the lens will be reported.

Refractive and Biometric Outcomes in Patients with Retinopathy of Prematurity Treated with Intravitreal Injection of Ranibizumab as Compared with Bevacizumab: A Clinical Study of Correction at Three Years of Age.

PubMed

Chen, Yen-Chih; Chen, San-Ni; Yang, Benjamin Chi-Lan; Lee, Kun-Hsien; Chuang, Chih-Chun; Cheng, Chieh-Yin

2018-01-01

To compare refractive and biometric outcomes in patients with type 1 retinopathy of prematurity (ROP) treated with intravitreal injection of ranibizumab (IVR) versus bevacizumab (IVB), at a corrected age of 3 years. A retrospective case series compared cycloplegic refractive statuses and biometric statuses in patients who received either IVR or IVB for type 1 ROP, from April 2011 to April 2014. A total of 62 eyes (33 patients) with type 1 ROP were evaluated (26 eyes in 13 IVR patients and 36 eyes in 20 IVB patients). There were no differences in birth statuses including gestational age and birth body weight between the two groups. The prevalence of refractive error greater than 1 D was higher in the IVB group ( p = 0.03), and there was a higher prevalence of high myopia (<-5.0 D, p = 0.03) in the IVB group. Comparisons in biometric finding showed that IVB patients had shallower anterior chamber depth ( p = 0.01). Both IVR and IVB showed low refractive errors, even followed at the corrected age of 3 years. No difference was noted between the two groups in refractive statuses. However, IVB was associated with shallower anterior chamber and higher prevalence of refractive error at the corrected age of 3 years. This trial is registered with NCT03334513.

Experimental microendoscopic photoablative laser goniotomy as a surgical model for the treatment of dysgenetic glaucoma.

PubMed

Jacobi, P C; Dietlein, T S; Krieglstein, G K

1996-11-01

The aim of this study was to investigate the feasibility of photoablative Er:YAG laser goniotomy under microendoscopic control in a surgical cloudy corneal model of primary infantile glaucoma. Pectinate ligaments of 12 freshly enucleated cadaver porcine eyes were treated by ab interno single-pulse (5 mJ, 200 microseconds) Er:YAG laser (2.94 microns) photoablation. Through a clear corneal incision near the limbus an ophthalmic microendoscope (18 and 20 gauge) was inserted into the anterior chamber. Internal structures were observed and photoablative laser goniotomy was conducted under video guidance. Following treatment all eyes were prepared for light and scanning electron microscopy. Anterior chamber angle structures and tissue photoablation were clearly visualized on the videoscreen using ophthalmic microendoscopy. Energy settings of 5 mJ per pulse proved to be sufficient for reproducible photoablation of pectinate ligaments, accompanied by the root of the iris falling back and exposing trabecular meshwork. This was confirmed histopathologically. Scatter thermal damage was less than 30 microns. This new therapeutic modality, which combines endoscopic visualization of the internal structures with photoablative laser goniotomy, can be effective in the management of dysgenetic glaucoma in the presence of a cloudy cornea. High reproducibility of contact laser photoablation enabled sufficient control of incision depth and was not accompanied by inadvertent tissue damage to adjacent intraocular structures.

Static and dynamic crystalline lens accommodation evaluated using quantitative 3-D OCT.

PubMed

Gambra, Enrique; Ortiz, Sergio; Perez-Merino, Pablo; Gora, Michalina; Wojtkowski, Maciej; Marcos, Susana

2013-01-01

Custom high-resolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT) provided with automatic quantification and distortion correction algorithms was used to characterize three-dimensionally (3-D) the human crystalline lens in vivo in four subjects, for accommodative demands between 0 to 6 D in 1 D steps. Anterior and posterior lens radii of curvature decreased with accommodative demand at rates of 0.73 and 0.20 mm/D, resulting in an increase of the estimated optical power of the eye of 0.62 D per diopter of accommodative demand. Dynamic fluctuations in crystalline lens radii of curvature, anterior chamber depth and lens thickness were also estimated from dynamic 2-D OCT images (14 Hz), acquired during 5-s of steady fixation, for different accommodative demands. Estimates of the eye power from dynamical geometrical measurements revealed an increase of the fluctuations of the accommodative response from 0.07 D to 0.47 D between 0 and 6 D (0.044 D per D of accommodative demand). A sensitivity analysis showed that the fluctuations of accommodation were driven by dynamic changes in the lens surfaces, particularly in the posterior lens surface.

Static and dynamic crystalline lens accommodation evaluated using quantitative 3-D OCT

PubMed Central

Gambra, Enrique; Ortiz, Sergio; Perez-Merino, Pablo; Gora, Michalina; Wojtkowski, Maciej; Marcos, Susana

2013-01-01

Custom high-resolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT) provided with automatic quantification and distortion correction algorithms was used to characterize three-dimensionally (3-D) the human crystalline lens in vivo in four subjects, for accommodative demands between 0 to 6 D in 1 D steps. Anterior and posterior lens radii of curvature decreased with accommodative demand at rates of 0.73 and 0.20 mm/D, resulting in an increase of the estimated optical power of the eye of 0.62 D per diopter of accommodative demand. Dynamic fluctuations in crystalline lens radii of curvature, anterior chamber depth and lens thickness were also estimated from dynamic 2-D OCT images (14 Hz), acquired during 5-s of steady fixation, for different accommodative demands. Estimates of the eye power from dynamical geometrical measurements revealed an increase of the fluctuations of the accommodative response from 0.07 D to 0.47 D between 0 and 6 D (0.044 D per D of accommodative demand). A sensitivity analysis showed that the fluctuations of accommodation were driven by dynamic changes in the lens surfaces, particularly in the posterior lens surface. PMID:24049680

Preoperative and postoperative size and movements of the lens capsular bag: ultrasound biomicroscopy analysis.

PubMed

Modesti, Marina; Pasqualitto, Giacomo; Appolloni, Rossella; Pecorella, Irene; Sourdille, Philippe

2011-10-01

To evaluate capsular bag size and accommodative movement before and after cataract surgery using ultrasound biomicroscopy (UBM) and anterior segment optical coherence tomography (AS-OCT). Ophthalmology Unit, Fabia Mater Clinic, Rome, Italy. Cohort study. Eyes having cataract surgery and monofocal intraocular lens (IOL) implantation were studied using UBM. The following parameters were measured preoperatively and 1, 2, and 12 months postoperatively: anterior chamber depth (ACD) (also by AS-OCT), capsular bag thickness, capsular bag diameter, ciliary ring diameter, sulcus-to-sulcus (STS) diameter, ciliary process-capsular bag distance, ciliary apex-capsular bag plane, and IOL tilting. The preoperative and postoperative capsular bag volumes were calculated at 12 months. The results were compared with the changes during accommodation. The study comprised 24 eyes. With the exception of the ciliary apex-capsular bag plane, which appeared to be unmodified postoperatively, all measured parameters showed significant variation after IOL implantation. Only the ACD did not change significantly during accommodation. After cataract surgery, the capsular bag stretched horizontally and with reduced vertical diameter as a result of adaptation to the implanted IOL. The capsular bag-IOL complex filled all available space, compressing the zonular fibers and almost abolishing the space between the ciliary apex and the capsular bag. There was anterior chamber deepening and a decrease in the ciliary ring diameter and STS diameter. In the absence of zonular fiber tension, the shape of the ciliary processes may be modified. No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Distinct iris gene expression profiles of primary angle closure glaucoma and primary open angle glaucoma and their interaction with ocular biometric parameters.

PubMed

Seet, Li-Fong; Narayanaswamy, Arun; Finger, Sharon N; Htoon, Hla M; Nongpiur, Monisha E; Toh, Li Zhen; Ho, Henrietta; Perera, Shamira A; Wong, Tina T

2016-11-01

This study aimed to evaluate differences in iris gene expression profiles between primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) and their interaction with biometric characteristics. Prospective study. Thirty-five subjects with PACG and thirty-three subjects with POAG who required trabeculectomy were enrolled at the Singapore National Eye Centre, Singapore. Iris specimens, obtained by iridectomy, were analysed by real-time polymerase chain reaction for expression of type I collagen, vascular endothelial growth factor (VEGF)-A, -B and -C, as well as VEGF receptors (VEGFRs) 1 and 2. Anterior segment optical coherence tomography (ASOCT) imaging for biometric parameters, including anterior chamber depth (ACD), anterior chamber volume (ACV) and lens vault (LV), was also performed pre-operatively. Relative mRNA levels between PACG and POAG irises, biometric measurements, discriminant analyses using genes and biometric parameters. COL1A1, VEGFB, VEGFC and VEGFR2 mRNA expression was higher in PACG compared to POAG irises. LV, ACD and ACV were significantly different between the two subgroups. Discriminant analyses based on gene expression, biometric parameters or a combination of both gene expression and biometrics (LV and ACV), correctly classified 94.1%, 85.3% and 94.1% of the original PACG and POAG cases, respectively. The discriminant function combining genes and biometrics demonstrated the highest accuracy in cross-validated classification of the two glaucoma subtypes. Distinct iris gene expression supports the pathophysiological differences that exist between PACG and POAG. Biometric parameters can combine with iris gene expression to more accurately define PACG from POAG. © 2016 The Authors. Clinical & Experimental Ophthalmology published by John Wiley & Sons Australia, Ltd on behalf of Royal Australian and New Zealand College of Ophthalmologists.

Relationship between relative lens position and appositional closure in eyes with narrow angles.

PubMed

Otori, Yasumasa; Tomita, Yuki; Hamamoto, Ayumi; Fukui, Kanae; Usui, Shinichi; Tatebayashi, Misako

2011-03-01

To investigate the relationship between relative lens position (RLP) and appositional closure in eyes with narrow angles. Ultrasound biomicroscopy (UBM) was used to measure anterior chamber depth (ACD) and lens thickness (LT), and the IOLMaster to measure axial length (AL). The number of quadrants with appositional closure was assessed by UBM under dark conditions. The RLP was calculated thus: RLP = 10 × (ACD + 0.5 LT) /AL. This study comprised 30 consecutive patients (30 eyes) with narrow-angle eyes defined as Shaffer grade 2 or lower and without peripheral anterior synechiae (24 women, 6 men; mean age ± SD, 67.3 ± 10.4 years; range, 42-87 years). Under dark conditions, 66.7% of the eyes with narrow angles showed appositional closure in at least one quadrant. Of the various ocular biometric parameters, only the RLP significantly decreased with appositional closure in at least one quadrant (P = 0.005). A decrease in the RLP can be predictive of appositional closure for narrow-angle eyes under dark conditions.

Automated 3-D cell counting method for grading uveitis of rodent eye in vivo with optical coherence tomograph.

PubMed

Choi, Woo June; Pepple, Kathryn L; Wang, Ruikang K

2018-05-24

In preclinical vision research, cell grading in small animal models is essential for the quantitative evaluation of intraocular inflammation. Here, we present a new and practical optical coherence tomography (OCT) image analysis method for the automated detection and counting of aqueous cells in the anterior chamber (AC) of a rodent model of uveitis. Anterior segment OCT (AS-OCT) images are acquired with a 100kHz swept-source OCT (SS-OCT) system. The proposed method consists of two steps. In the first step, we first despeckle and binarize each OCT image. After removing AS structures in the binary image, we then apply area thresholding to isolate cell-like objects. Potential cell candidates are selected based on their best fit to roundness. The second step performs the cell counting within the whole AC, in which additional cell tracking analysis is conducted on the successive OCT images to eliminate redundancy in cell counting. Finally, 3-D cell grading using the proposed method is demonstrated in longitudinal OCT imaging of a mouse model of anterior uveitis in vivo. Rendering of anterior segment (orange) of mouse eye and automatically counted anterior chamber cells (green). Inset is a top view of the rendering, showing the cell distribution across the anterior chamber. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Scheimpflug image-based changes in anterior segment parameters during accommodation induced by short-term reading.

PubMed

Lipecz, Agnes; Tsorbatzoglou, Alexis; Hassan, Ziad; Berta, Andras; Modis, Laszlo; Nemeth, Gabor

2017-05-11

To analyze the effect of the accommodation on the anterior segment data (corneal and anterior chamber parameters) induced by short-time reading in a healthy, nonpresbyopic adult patient group. Images of both eyes of nonpresbyopic volunteers were captured with a Scheimpflug device (Pentacam HR) in a nonaccommodative state. Fifteen minutes of reading followed and through fixation of the built-in target of Pentacam HR further accommodation was achieved and new images were captured by the device. Anterior segment parameters were observed and the differences were analyzed. Fifty-two healthy eyes of 26 subjects (range 20.04-28.58 years) were analyzed. No significant differences were observed in the keratometric values before and after the accommodative task (p = 0.35). A statistically significant difference was measured in the 5.0-mm-diameter and the 7.0-mm-diameter corneal volume (p = 0.01 and p = 0.03) between accommodation states. Corneal aberrometric data did not change significantly during short-term accommodation. Significant differences were observed between nonaccommodative and accommodative states of the eyes for all measured anterior chamber parameters. Among the parameters of the cornea, only corneal volume changed during the short-term accommodation process, showing some fine changes with accommodation of the cornea in young, emmetropic patients. The position of the pupil and the anterior chamber parameters were observed to change with accommodation as captured by a Scheimpflug device.

[Comparison of anterior chamber angle examination by UBM, SL-OCT and gonioscopy].

PubMed

Liu, Rui-jue; Wang, Men; Xia, Wen-tao; Yu, Xiao-ying; Chen, Jie-min; Zhou, Shu; Peng, Shu-ya; Liu, Dong-mei

2014-08-01

To compare the agreement of anterior chamber angle examination by ultrasound biomicroscope (UBM), slit lamp optical coherence tomography (SL-OCT), and gonioscopy in angle recession and angle closure. The anterior chamber angle was measured with UBM, SL-OCT and gonioscopy in turns for temporal, nasal, superior and inferior quadrant in the same dark room. The results were compared with the agreement of the three methods in angle recession and angle closure by χ2 test and Kappa test. There were no statistically significant differences of the three methods in testing angle closure and angle recession (P>0.05). The consistency of UBM and gonioscopy was better (Kappa value of 0.882) than that of SL-OCT and gonioscopy (Kappa value of 0.624). When testing angle recession, UBM is better than SL-OCT with gonioscopy as the standard. When testing angle closure, UBM, SL-OCT and gonioscopy have good agreement.

A new species of the genus Triplophysa (Cypriniformes: Nemacheilidae), Triplophysa daochengensis, from Sichuan Province, China

PubMed Central

WU, Yu-Yi; SUN, Zhi-Yu; GUO, Yan-Shu

2016-01-01

Triplophysa daochengensis sp. nov. is described from the Daocheng River, a northern tributary of the Jinsha River in Sichuan Province, China. The new species can be distinguished from its congeners by the following characters: body smooth and scales absent; lateral line complete; caudal peduncle compressed, depth unchanging; head length equal to caudal-peduncle length; lower jaw shovel-shaped; dorsal-fin origin anterior to pelvic-fin origin and closer to the tip of the snout than to the caudal-fin base, last unbranched ray hard; pelvic-fin tip not reaching anus; posterior chamber of gas bladder absent; intestine of spiral type with three winding coils. PMID:27686788

Comparison of OVD and BSS for Maintaining the Anterior Chamber during IOL Implantation

PubMed Central

Lee, Ho Young; Choy, Yoon Jung

2011-01-01

Purpose To compare surgical results between conventional intraocular lens (IOL) implantation using an ophthalmic viscosurgical device (OVD) and IOL implantation using a balanced salt solution (BSS) after irrigation/aspiration (I/A) of the lens cortex. Methods A randomized prospective study was conducted on 62 patients who underwent cataract surgery. Following completion of conventional I/A of the lens cortex, we divided patients into two groups according to whether or not BSS was used. In group A (n = 31), the anterior chamber and the capsular bag were completely filled with an OVD before IOL implantation. On the other hand, in group B (n = 31), BSS was irrigated into the anterior chamber through a previous side port during IOL implantation. Surgical results were compared between the two groups. Results In both groups, IOP peaked six hours after surgery. The occurrence of an IOP spike by postoperative day one was observed in six cases (6 / 31) in group A and in no cases (0 / 31) in group B, a difference that was statistically significant (p = 0.024). The values of endothelial cell density, central corneal thickness, anterior chamber inflammation, myopic shift, and posterior capsule opacification were not significantly different between the two groups. Conclusions Compared with the use of OVD for IOL implantation, use of BSS during IOL implantation resulted in reductions in postoperative IOP spike and OVD removal time. PMID:21350689

Racial differences in ocular oxidative metabolism: implications for ocular disease.

PubMed

Siegfried, Carla J; Shui, Ying-Bo; Holekamp, Nancy M; Bai, Fang; Beebe, David C

2011-07-01

To compare the Po(2) distribution in different regions in the eyes of patients undergoing intraocular surgery. Before initiation of intraocular cataract and/or glaucoma surgery, an optical oxygen sensor was introduced into the anterior chamber via a peripheral corneal paracentesis. The tip of the flexible fiberoptic probe was positioned by the surgeon for 3 measurements in all patients: (1) near the central corneal endothelium, (2) in the mid-anterior chamber, and (3) in the anterior chamber angle. In patients scheduled to undergo cataract extraction, Po(2) was also measured (4) at the anterior lens surface and (5) in the posterior chamber just behind the iris. Oxygen measurements at the 5 locations were compared using a 2-tailed unpaired t test and multivariate regression. The Po(2) value was significantly higher in African American patients at all 5 locations compared with Caucasian patients. Adjusting for age increased the significance of this association. Adjusting for race revealed that age was associated with increased Po(2) beneath the central cornea. Racial differences in oxygen levels in the human eye reflect an important difference in oxidative metabolism in the cornea and lens and may reflect differences in systemic physiologic function. Increased oxygen or oxygen metabolites may increase oxidative stress, cell damage, intraocular pressure, and the risk of developing glaucoma. Oxygen use by the cornea decreases with age.

Effects of diurnal, lighting, and angle-of-incidence variation on anterior segment optical coherence tomography (AS-OCT) angle metrics.

PubMed

Akil, Handan; Dastiridou, Anna; Marion, Kenneth; Francis, Brian A; Chopra, Vikas

2017-03-23

First reported study to assess the effect of diurnal variation on anterior chamber angle measurements, as well as, to re-test the effects of lighting and angle-of-incidence variation on anterior chamber angle (ACA) measurements acquired by time-domain anterior segment optical coherence tomography (AS-OCT). A total of 30 eyes from 15 healthy, normal subjects underwent anterior chamber imaging using a Visante time-domain AS-OCT according to an IRB-approved protocol. For each eye, the inferior angle was imaged twice in the morning (8 am - 10 am) and then again in the afternoon (3 pm - 5 pm), under light meter-controlled conditions with ambient room lighting 'ON' and lights 'OFF', and at 5° angle of incidence increments. The ACA metrics measured for each eye were: angle opening distance (AOD, measured 500 and 750 μm anterior from scleral spur), the trabecular-iris-space area (TISA, measured 500 and 750 μm anterior from scleral spur), and scleral spur angle. Measurements were performed by masked, certified Reading Center graders using the Visante's Internal Measurement Tool. Differences in measurements between morning and afternoon, lighting variations, and angle of incidence were compared. Mean age of the participants was 31.2 years (range 23-58). Anterior chamber angle metrics did not differ significantly from morning to afternoon imaging, or when the angle of incidence was offset by 5° in either direction away from the inferior angle 6 o'clock position. (p-value 0.13-0.93). Angle metrics at the inferior corneal limbus, 6 o'clock position (IC270), with room lighting 'OFF', showed a significant decrease (p < 0.05) compared to room lighting 'ON'. There does not appear to be significant diurnal variation in AS-OCT parameters in normal individuals, but lighting conditions need to be strictly controlled since variation in lighting led to significant variability in AS-OCT parameters. No changes in ACA parameters were noted by varying the angle-of-incidence, which gives confidence in being able to perform longitudinal studies in approximately the same area (plus/minus 5° of original scan location).

Clinical and biometric determinants of actual lens position after cataract surgery.

PubMed

Plat, Julien; Hoa, Didier; Mura, Frederic; Busetto, Timothe; Schneider, Christelle; Payerols, Arnaud; Villain, Max; Daien, Vincent

2017-02-01

To evaluate the preoperative clinical and biometric determinants associated with the actual lens position after cataract surgery. Department of Ophthalmology, University Hospital of Montpellier, France. Prospective longitudinal cohort study. The data collected included clinical factors (age, sex, history of vitrectomy) and biometry factors (axial length [AL], anterior chamber depth [ACD], lens thickness, white-to-white [WTW] distance) that might affect actual lens position. Each patient had optical low-coherence reflectometry biometry (Lenstar) preoperatively and 1 month postoperatively. The actual lens position was measured as the postoperative position of the center of the intraocular lens (IOL). Patients were stratified into 3 groups by type of IOL: Acrysof SN60WF or SN6AT (Group 1), Tecnis ZCB00 or ZCT (Group 2), and Asphina 409 MV (Group 3). The study comprised 168 eyes (mean age 73.3 years ± 9.8 [SD]). The mean actual lens position was 4.88 ± 0.29 mm, 5.01 ± 0.29 mm, and 5.05 ± 0.32 mm in Group 1 (n = 67 eyes), Group 2 (n = 52 eyes), and Group 3 (n = 49 eyes), respectively. In the overall population, AL, ACD, anterior segment depth, and WTW distance were correlated with actual lens position (r = 0.48, P < .0001; r = 0.64, P < .001; r = 0.58, P < .0001; r = 0.39, P < .001, respectively). The AL, ACD, anterior segment depth, and WTW distance correlated with actual lens position after cataract surgery. The integration of these data in IOL formulas could help improve refractive outcomes after the surgery. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Neovascular Glaucoma After Stereotactic Radiotherapy for Juxtapapillary Choroidal Melanoma: Histopathologic and Dosimetric Findings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernandes, Bruno F.; Weisbrod, Daniel; Yuecel, Yeni H.

2011-06-01

Purpose: Enucleation after stereotactic radiotherapy (SRT) for juxtapapillary choroidal melanoma may be required because of tumor progression (TP) or the development of intractable radiation-induced neovascular glaucoma (NVG). We compare pathologic changes and dosimetric findings in those eyes enucleated secondary to NVG as opposed to TP to better understand potential mechanisms. Methods and Materials: Patients with juxtapapillary choroidal melanoma treated with SRT (70 Gy in 5 fractions, alternate days over a total of 10 days) at the Princess Margaret Hospital, Toronto, Ontario, Canada, who underwent enucleation between 1998 and 2006 were selected. We correlated dosimetric data based on the patient's originalmore » SRT treatment plan with histopathologic findings in the retina, optic nerve head, and anterior chamber. A dedicated ocular pathologist reviewed each case in a blinded fashion. Results: Ten eyes in ten patients were enucleated after SRT. Six were enucleated secondary to NVG and four secondary to because of TP. Aggressive tumor features such as invasion of the sclera and epithelioid cell type were observed predominantly in the TP group. Retinal damage was more predominant in the NVG group, as were findings of radiation-related retinal vascular changes of fibrinoid necrosis and hyalinization. No conclusive radiation-related effects were found in the anterior chamber. The maximum point dose and dose to 0.1 cc were lower for the anterior chamber as compared with the dose to the tumor, retina, and optic nerve head. The mean 0.1-cc doses to the retina were 69.4 Gy and 73.5 Gy and to the anterior chamber were 4.9 Gy and 17.3 Gy for the NVG group and tumor progression group, respectively. Conclusions: Our findings suggest that NVG is due to radiation damage to the posterior chamber of the eye rather than primary radiation damage to the anterior segment.« less

Sensitivity, specificity and predictive values of anterior chamber tap in cases of bacterial endophthalmitis.

PubMed

Sjoholm-Gomez de Liano, Carl; Soberon-Ventura, Vidal F; Salcedo-Villanueva, Guillermo; Santos-Palacios, Abril; Guerrero-Naranjo, Jose Luis; Fromow-Guerra, Jans; García-Aguirre, Gerardo; Morales-Canton, Virgilio; Velez-Montoya, Raul

2017-01-01

To assess the sensitivity, specificity, positive predictive value and negative predictive value of anterior chamber tap for the diagnosis of bacterial endophthalmitis on a population with high prevalence. Retrospective, single centre, case series study. We reviewed all medical records with clinical diagnosis of bacterial endophthalmitis in our hospital from January 1st, 2000 to December 31st 2014. From each record, we documented general demographic data, best corrected visual acuity and vitreous and aqueous tap microbiological results. All cases were further divided according to the endophthalmitis aetiology to perform individual calculations of sensitivity, specificity, positive predictive value, negative predictive value, accuracy and prevalence. We used the results of the vitreous tap as the gold standard for diagnosis of bacterial endophthalmitis. We excluded those records in which the aqueous and vitreous samples were not taken simultaneously or had an incomplete microbiological report. Significance were assessed with chi squared statistics, with an alpha value of 0.05 for statistical significance. A total of 190 cases fulfilled the inclusion/exclusion criteria. Positive culture rate from vitreous samples was 64.74%. Positive culture rate from aqueous sample was 32.11%. Bacteria isolated from aqueous samples matched those isolated from vitreous samples 78.68% of the time. The overall sensitivity was 38.21%, specificity: 75.51%, positive predictive value: 79.66%, negative predictive value: 32.74% ( p  = 0.08). Subgroup analysis showed that anterior chamber taps in cases of post-surgical endophthalmitis had a moderate to low sensitivity (37.73%), high specificity (93%) and high positive predictive value (95%) ( p  < 0.04). The sensitivity and specificity of anterior chamber tap are low and should not be used for critical therapeutic decisions in patients with suspected bacterial endophthalmitis. In cases of post-surgical endophthalmitis, the result of an anterior chamber tap could be used for therapeutic guidance, but only in conjunction with clinical presentation and in the absence of a better method for diagnosis.

A Novel Method of Quantitative Anterior Chamber Depth Estimation Using Temporal Perpendicular Digital Photography

PubMed Central

Zamir, Ehud; Kong, George Y.X.; Kowalski, Tanya; Coote, Michael; Ang, Ghee Soon

2016-01-01

Purpose We hypothesize that: (1) Anterior chamber depth (ACD) is correlated with the relative anteroposterior position of the pupillary image, as viewed from the temporal side. (2) Such a correlation may be used as a simple quantitative tool for estimation of ACD. Methods Two hundred sixty-six phakic eyes had lateral digital photographs taken from the temporal side, perpendicular to the visual axis, and underwent optical biometry (Nidek AL scanner). The relative anteroposterior position of the pupillary image was expressed using the ratio between: (1) lateral photographic temporal limbus to pupil distance (“E”) and (2) lateral photographic temporal limbus to cornea distance (“Z”). In the first chronological half of patients (Correlation Series), E:Z ratio (EZR) was correlated with optical biometric ACD. The correlation equation was then used to predict ACD in the second half of patients (Prediction Series) and compared to their biometric ACD for agreement analysis. Results A strong linear correlation was found between EZR and ACD, R = −0.91, R2 = 0.81. Bland-Altman analysis showed good agreement between predicted ACD using this method and the optical biometric ACD. The mean error was −0.013 mm (range −0.377 to 0.336 mm), standard deviation 0.166 mm. The 95% limits of agreement were ±0.33 mm. Conclusions Lateral digital photography and EZR calculation is a novel method to quantitatively estimate ACD, requiring minimal equipment and training. Translational Relevance EZ ratio may be employed in screening for angle closure glaucoma. It may also be helpful in outpatient medical clinic settings, where doctors need to judge the safety of topical or systemic pupil-dilating medications versus their risk of triggering acute angle closure glaucoma. Similarly, non ophthalmologists may use it to estimate the likelihood of acute angle closure glaucoma in emergency presentations. PMID:27540496

The effect of vitrectomy with silicone oil tamponade on intraocular pressure and anterior chamber morphology.

PubMed

Suic, S P; Sikić, J

2001-01-01

We measured the tamponading effect of silicone oil, saline and air after vitrectomy, on intraocular pressure and aqueous humor outflow in 85 patients with highly proliferative retina and vitreous changes. Silicone oil as retinal tamponading agent after vitrectomy was used in 45 patients, and saline or air in 39 patients. The mean intraocular pressure measured at one month after treatment was greatly elevated in patients with silicone oil tamponade as compared to those with saline or air tamponade. At 6 and 12 months examinations, mean intraocular pressures were compared in these two groups of patients. Gonioscopy revealed silicone oil emulsification and presence of emulsified bubbles in the anterior chamber in 22.22% of patients, and narrowing of the chamber angle in several patients with silicone oil tamponade. Intraocular pressure elevation following vitrectomy with silicone oil tamponade was found to be of transient rather than permanent nature, since it regressed after silicone oil removal. This transient elevation was due to silicone oil tendency to emulsify. Silicone oil bubbles changed the morphology of the anterior chamber angle and fine trabecular structures by creating a barrier to aqueous humor outflow.

Evaluation of the lamina cribrosa in patients with diabetes mellitus using enhanced depth imaging spectral-domain optical coherence tomography.

PubMed

Akkaya, Serkan; Küçük, Bekir; Doğan, Hatice Karaköse; Can, Ertuğrul

2018-06-01

To compare the lamina cribrosa thickness and anterior lamina cribrosa depth between patients with and without diabetes mellitus and to investigate the effect of metabolic control and duration of diabetes mellitus on lamina cribrosa thickness and anterior lamina cribrosa depth using enhanced depth imaging spectral-domain optical coherence tomography. A total of 70 patients were enrolled in this cross-sectional study and were divided into the diabetes and control groups. Intraocular pressure, circumpapillary retinal nerve fibre layer thickness, anterior lamina cribrosa depth and lamina cribrosa thickness were compared between the groups. In the control group, the mean intraocular pressure was 14.6 ± 3.1 (mean ± standard deviation) mmHg, mean circumpapillary retinal nerve fibre layer thickness was 105.41 ± 5.86 μm, mean anterior lamina cribrosa depth was 420.3 ± 90.2 μm and mean lamina cribrosa thickness was 248.5 ± 5.4 μm. In the diabetes group, the mean intraocular pressure was 13.9 ± 2.2 mmHg, mean circumpapillary retinal nerve fibre layer thickness was 101.37 ± 10.97 μm, mean anterior lamina cribrosa depth was 351.4 ± 58.6 μm and mean lamina cribrosa thickness was 271.6 ± 33.9 μm. Lamina cribrosa thickness was significantly higher ( p < 0.001) and anterior lamina cribrosa depth was significantly lower ( p = 0.003) in the diabetes group. There was no statistical difference between the groups with regard to age, spherical equivalent, axial length, circumpapillary retinal nerve fibre layer thickness and intraocular pressure ( p  = 0.69, 0.26, 0.47, 0.06 and 0.46, respectively). Lamina cribrosa thickness and anterior lamina cribrosa depth were not significantly correlated with duration of diabetes mellitus (lamina cribrosa thickness: r = -0.078, p = 0.643; anterior lamina cribrosa depth: r = -0.062, p = 0.710) or HbA1c levels (lamina cribrosa thickness: r = -0.078, p = 0.596; anterior lamina cribrosa depth: r = -0.228, p = 0.169). The results of this study showed that the optical coherence tomography measurement of lamina cribrosa revealed thicker and more anteriorly positioned lamina cribrosa for patients with diabetes mellitus compared with those for healthy controls.

The clinical outcomes of surgical management of anterior chamber migration of a dexamethasone implant (Ozurdex®).

PubMed

Kang, Hyunseung; Lee, Min Woo; Byeon, Suk Ho; Koh, Hyoung Jun; Lee, Sung Chul; Kim, Min

2017-09-01

Our purpose was to describe the clinical course, and individualized management approaches, of patients with migration of a dexamethasone implant into the anterior chamber. This was a retrospective review of four patients with seven episodes of anterior chamber migration of a dexamethasone implant. After 924 intravitreal dexamethasone injections, anterior migration of the implant occurred in four eyes of four patients (0.43%). All four eyes were pseudophakic: one eye had a posterior chamber intraocular lens in the capsular bag but in a post-laser posterior capsulotomy state, two eyes had a sulcus intraocular lens (IOL), and one eye had an iris-fixated retropupillary IOL. All eyes had a prior vitrectomy and no lens capsule. The time interval from injection to detection of the implant migration ranged from 2 to 6 weeks. Of the four eyes with corneal edema, only one eye required a corneal transplantation, although it was unclear whether the implant migration was the direct cause of the corneal decompensation because the patient had a history of bullous keratopathy resulting from an extended history of uveitis. All patients underwent surgical intervention: two patients with a repositioning procedure, and the other two patients with removal due to repeated episodes, although surgical removal was not always necessary to reverse the corneal complications. In our study, not all patients required surgical removal of the implants. Repositioning the implant back into the vitreous cavity may be considered as an option in cases involving the first episode with no significant corneal endothelial decompensation. Considering potential anterior segment complications and the loss of drug effectiveness together, an individualized approach is recommended to obtain the best treatment outcomes and to minimize the risk of corneal complications.

Comparison of circumferential peripheral angle closure using iridotrabecular contact index after laser iridotomy versus combined laser iridotomy and iridoplasty.

PubMed

Cho, Hyun-Kyung; Kee, Changwon; Yang, Heon; Huh, Hyoun Do; Kim, Su Jin; Park, Young Min; Park, Jong Moon

2017-11-01

To compare the quantitative changes of peripheral angle after laser iridotomy (LI) alone (group A) or combined LI and Iridoplasty (group B) using iridotrabecular contact (ITC) index by swept-source anterior segment optical coherence tomography (AS-OCT). In this prospective comparative observational study, OCT images were obtained before and after the procedure. In each image frame, scleral spur (SS) and the ITC end point (EP) were marked and ITC index was calculated as a percentage of the angle closure from 360°. Age, gender, diagnosis and initial ITC index in Group B were matched with group A. Changes in ITC index, anterior chamber angle parameters, and intraocular pressure (IOP) were inspected. Thirty-three eyes (20 patients) with shallow anterior chamber were included in each group. Initial ITC index and initial IOP were not significantly different between the two groups (both p > 0.05). However, ITC index and IOP after the procedure were significantly lower in group B than those in group A (ITC index: 31.3 ± 23.2 in group A, 19.0 ± 21.3 in group B, p = 0.011, IOP: p = 0.004). All anterior chamber angle parameters in group B and all parameters in group A except nasal trabecular-iris angles (TIA) were significantly increased after the laser procedure (all p < 0.05). In patients with shallow anterior chamber, combined LI and Iridoplasty may open the peripheral angle better than LI alone. Iridoplasty may be able to additionally relieve the peripheral angle closure caused by other mechanisms than pupillary block. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Anterior Chamber Angle Measurements Using Schwalbe's Line with High Resolution Fourier-Domain Optical Coherence Tomography

PubMed Central

Qin, Bing; Francis, Brian A.; Li, Yan; Tang, Maolong; Zhang, Xinbo; Jiang, Chunhui; Cleary, Catherine; Huang, David

2012-01-01

Purpose To use Fourier-domain optical coherence tomography (OCT) to measure the angle opening distance at Schwalbe's line (AOD-SL) and determine its value in anterior chamber angle assessment. Methods Horizontal scans of the nasal and temporal anterior chamber angles in glaucoma subjects were performed by 830 nm wavelength Fourier-domain OCT. Images were graded by two ophthalmologists who assessed the visibility of Schwalbe’s line (SL), anterior limbus (AL), scleral spur (SS), and angle recess (AR). AOD-SL was measured with computer calipers. SL was manually identified by the termination of the corneal endothelium. Gonioscopy was used to classify anterior chamber angles according to a modified Shaffer system. Spearman's rho analysis was performed to assess correlation between AOD-SL and modified Shaffer grade. A cut-off value of AOD-SL for diagnosing occludable angles (modified Shaffer grade ≤1) was determined by receiver operating characteristic (ROC) analyses. Results Thirty-five glaucoma subjects (65 eyes) were enrolled. SL, AL, AR, and SS were visible by OCT in 97.7%, 99.2%, 87.3%, and 80.8% of eyes, respectively. Nasal and temporal AOD-SLs were 322.6 ± 200.2 µm and 341.4 ± 197.4 µm, respectively. Correlation coefficients between AOD-SL and modified Shaffer grade were 0.80 (nasal) and 0.81 (temporal). The diagnostic cut-off value of AOD-SL for occludable angles was 290 µm. The areas under the ROC curve, sensitivity, specificity values were 0.90, 0.80, 0.87 (nasal) and 0.90, 0.85, 0.77 (temporal). Conclusions The measurement of AOD-SL by Fourier-domain OCT is highly correlated with gonioscopy and may be a useful noncontact method of assessing angle closure risk. PMID:22827999

The ocular biometric differences of diabetic patients.

PubMed

Kocatürk, Tolga; Zengin, Mehmet Özgür; Cakmak, Harun; Evliçoglu, Gökhan Evren; Dündar, Sema Oruç; Omürlü, Imran Kurt; Unübol, Mustafa; Güney, Engin

2014-01-01

To investigate the differences in ocular biometric and keratometric characteristics in comparison with biometric measurements using the noncontact optical low coherence reflectometer (OLCR) (Lenstar LS 900, Haag-Streit) on diabetic patients. The eyes of 170 patients were included in this study, including 81 diabetic and 89 nondiabetic subjects. Optical biometric measurements of diabetic and nondiabetic patients (between the ages of 25 and 85 years) who applied to the ophthalmology clinic were noted from March to June 2013. Detailed ophthalmologic examinations were done for every subject. Biometric measurements were done using the noncontact OLCR device. Patient age ranged from 29 to 83 years. Subgroup analyses were done in diabetic patients according to their Hba1C levels. The minimum Hba1C value was 5.3, maximum was 12.4, and mean was 7.56 ± 1.48. The median duration of diabetes was 5 years (25th-75th percentile 3.00-11.75). Diabetic patients were found to have thicker lens and shallower anterior chamber in both eyes compared to nondiabetic control subjects. There were no statistical differences between the groups according to central corneal thickness, axial length, or keratometric values in both eyes. However, lens thicknesses were found to be thicker and anterior chamber depth values were found to be shallower in the diabetic group in both eyes. It may useful to determine eyeglasses prescription, refractive surgery calculation, lens selection, and previous cataract surgery according to biometric measurements after the regulation of blood glucose.

A chandelier-illuminated anterior chamber maintainer for use during descemet stripping automated endothelial keratoplasty in patients with advanced bullous keratopathy.

PubMed

Inoue, Tomoyuki; Oshima, Yusuke; Hori, Yuich; Maeda, Naoyuki

2010-08-01

A new 25-gauge illuminated anterior chamber maintainer composed of a 25-gauge infusion cannula through which a 29-gauge chandelier fiber probe passes was developed for use during Descemet stripping automated endothelial keratoplasty to treat patients with advanced bullous keratopathy. This device, which is compatible with a xenon or mercury vapor illuminator to generate powerful wide-angle illumination from the cone-shaped chandelier fiber tip, is self-retained at the corneal limbus after insertion of the infusion cannula through a corneal side port. Because of its bifunctionality, that is, bright illumination and adequate irrigation flow, excellent visibility with stable anterior chamber maintenance can be concurrently obtained for Descemet stripping, endothelial graft insertion, and subsequent intraocular manipulations without the need for use of a biologic staining technique or ophthalmic viscosurgical products even in patients with severe corneal haze. This new device facilitates safe and simple intraocular manipulation during Descemet stripping automated endothelial keratoplasty.

A comparison between internal and surface temperature measurement techniques during phacoemulsification cataract surgery: thermocamera versus thermocouple.

PubMed

Innocenti, B; Diciotti, S; Bocchi, L; Mencucci, R; Corvi, A

2008-01-01

Corneal and scleral burns, one of the main complications that can occur during a cataract operation, are produced by overheating due to the use of the phacoemulsifier. The temperature of the anterior chamber of the eye can be measured both invasively using thermocouples and non-invasively, but only superficially, using a thermocamera. To compare the measures obtained from both techniques an in vitro experimental analysis was conducted on pigs' eyes. During a simulated phacoemulsification cataract operation both the surface temperature with a thermocamera and the temperature inside the anterior chamber with a thermocouple were recorded. For each procedure, the maximum temperature values measured by each technique were compared. The results of this research show that the difference between the maximum values measured with the two techniques is on average 0.5 degrees C. It is possible to employ a thermocamera technique instead of a thermocouple technique to provide an indication of the temperature inside the anterior chamber.

Cellular and Molecular Mechanisms of Anterior Chamber-Associated Immune Deviation (ACAID): What We Have Learned from Knockout Mice

PubMed Central

Vendomèle, Julie; Khebizi, Quentin; Fisson, Sylvain

2017-01-01

Anterior chamber-associated immune deviation (ACAID) is a well-known phenomenon that can occur after an antigen is introduced without any danger signal into the anterior chamber of a murine eye. It is reported to lead to an antigen-specific immune deviation throughout the body. Despite the relatively little evidence of this phenomenon in humans, it has been suggested as a potential prophylactic strategy in allograft rejections and in several autoimmune diseases. Cellular and molecular mechanisms of ACAID have been explored in different murine models mainly as proofs of concept, first by direct analyses of immune components in normal immunocompetent settings and by cell transfer experiments. Later, use of knockout (KO) mice has helped considerably to decipher ACAID mechanisms. However, several factors raise questions about the reliability and validity of studies using KO murine models. This mini-review summarizes results obtained with KO mice and discusses their advantages, their potential weaknesses, and their potential methods for further progress. PMID:29250068

Surgical management of malignant glaucoma: a retrospective analysis of fifty eight eyes.

PubMed

Balekudaru, S; Choudhari, N S; Rewri, P; George, R; Bhende, P S; Bhende, M; Lingam, V; Lingam, G

2017-06-01

PurposeTo assess outcomes of surgical management of malignant glaucoma in terms of re-formation of anterior chamberMethodsThis was a retrospective analysis of consecutive patients who underwent surgical treatment for malignant glaucoma between January 1995 and December 2013 at a tertiary care ophthalmic institute, with a minimum follow up of 2 months.ResultsFifty eight eyes of 58 patients were included. Fifty two (89.7%) patients had primary angle closure glaucoma. The majority had undergone glaucoma filtration surgery earlier (n=53, 91.4%). Lensectomy and anterior vitrectomy was performed in 15 (25.9%) eyes (Group 1). Vitrectomy and anterior chamber re-formation was performed in 27 (46.6%) eyes (Group 2). Vitrectomy-phacoemulsification-vitrectomy was performed in 16 (27.6%) eyes (Group 3). Communication between the two segments of eye through anterior hyaloid, lens capsule complex and/or iris was achieved in all groups. The median follow-up (Inter-quartile range) was 30 (71.5) months. Anterior chamber re-formation was achieved in 56 (96.5%) eyes at final visit. The improvement in mean±SD LogMAR visual acuity (1.1±1 to 0.7±0.8) and reduction in number ±SD of anti-glaucoma medications (2.1±1.1 to 1±1.6) between onset and final visit were significant (P=0.02 and <0.01, respectively). The intraocular pressure (mm Hg) at onset and at final visit was 30.7±17.4 and 14±6.2, 32.8±12.6 and 15.3±7.4, and 27.2±14 and 10.9±3 in groups 1-3, respectively (all P<0.01).ConclusionOur anatomical success rate was high. The key element in achieving this outcome was the establishment of a patent communication between the vitreous cavity and the anterior chamber.

Auto-cortex of crystalline lens-induced iris neovascularization

PubMed Central

Liu, Lin; Li, Yong-Ping; Zhang, Bo; Zhang, Wen-Xin

2012-01-01

AIM To investigate auto-cortex of crystalline lens induced iris neovascularization (INV). METHODS Thirty-six eyes of 36 guinea-pigs were included and divided into three groups randomly in this cohort study. Group A: the right lens nucleus was extracted and the remaining cortical lens material was aspirated thoroughly. Group B: the lens was removed and 30µL precipitated lens cortex was injected into the anterior chamber again. Group C: aspirated the lens cortex of the left eyes and inject them into the right anterior chambers about 10µL. Clinical changes were followed by slit-lamp examination and photograph. The eye balls were enucleated at the day of 2, 4, 7, 11, 13, 17 after operation. HE was used to detect the pathological changes. RESULTS Group A: INV had not been observed until the end of empirical study. The stromal layer contained thick wall vessels, without expansion. Group B: All eyes developed INV. Postoperative (po) 7 days; the eyes developed intense and extensive INV. The vessels of iris expanded remarkably and neovascularization was observed erupting from it's lateral wall and stretching towards the anterior surface. Po11 days, INV regressed gradually after lens cortex had been absorbed. Group C: Po four (4) days, new blood vessels liking red line were presented on the anterior surface of the iris and they were not obvious. CONCLUSION Anterior chamber inside lens coriaceous can induce iris new blood vessels. PMID:22553749

Prediction of accommodative optical response in prepresbyopic patients using ultrasound biomicroscopy

PubMed Central

Ramasubramanian, Viswanathan; Glasser, Adrian

2015-01-01

PURPOSE To determine whether relatively low-resolution ultrasound biomicroscopy (UBM) can predict the accommodative optical response in prepresbyopic eyes as well as in a previous study of young phakic subjects, despite lower accommodative amplitudes. SETTING College of Optometry, University of Houston, Houston, USA. DESIGN Observational cross-sectional study. METHODS Static accommodative optical response was measured with infrared photorefraction and an autorefractor (WR-5100K) in subjects aged 36 to 46 years. A 35 MHz UBM device (Vumax, Sonomed Escalon) was used to image the left eye, while the right eye viewed accommodative stimuli. Custom-developed Matlab image-analysis software was used to perform automated analysis of UBM images to measure the ocular biometry parameters. The accommodative optical response was predicted from biometry parameters using linear regression, 95% confidence intervals (CIs), and 95% prediction intervals. RESULTS The study evaluated 25 subjects. Per-diopter (D) accommodative changes in anterior chamber depth (ACD), lens thickness, anterior and posterior lens radii of curvature, and anterior segment length were similar to previous values from young subjects. The standard deviations (SDs) of accommodative optical response predicted from linear regressions for UBM-measured biometry parameters were ACD, 0.15 D; lens thickness, 0.25 D; anterior lens radii of curvature, 0.09 D; posterior lens radii of curvature, 0.37 D; and anterior segment length, 0.42 D. CONCLUSIONS Ultrasound biomicroscopy parameters can, on average, predict accommodative optical response with SDs of less than 0.55 D using linear regressions and 95% CIs. Ultrasound biomicroscopy can be used to visualize and quantify accommodative biometric changes and predict accommodative optical response in prepresbyopic eyes. PMID:26049831

Rotating drum variable depth sampler

DOEpatents

Nance, Thomas A [Aiken, SC; Steeper, Timothy J [Trenton, SC

2008-07-01

A sampling device for collecting depth-specific samples in silt, sludge and granular media has three chambers separated by a pair of iris valves. Rotation of the middle chamber closes the valves and isolates a sample in a middle chamber.

Crystalline lens thickness determines the perceived chromatic difference in magnification.

PubMed

Chen, Yun; Schaeffel, Frank

2014-03-01

Since the origin of the high interindividual variability of the chromatic difference in retinal image magnification (CDM) in the human eye is not well understood, optical parameters that might determine its magnitude were studied in 21 healthy subjects with ages ranging from 21 to 58 years. Two psychophysical procedures were used to quantify CDM. They produced highly correlated results. First, a red and a blue square, presented on a black screen, had to be matched in size by the subjects with their right eyes. Second, a filled red and blue square, flickering on top of each other at 2 Hz, had to be adjusted in perceived brightness and then in size to minimize the impression of flicker. CDM varied widely among subjects from 0.0% to 3.6%. Biometric ocular parameters were measured with low coherence interferometry and crystalline lens tilt and decentration with a custom-built Purkinjemeter. Correlations were studied between CDM and corneal power, anterior chamber depth, lens thickness, lens tilt and lens decentration, and vitreous chamber depths. Lens thickness was found significantly correlated with CDM and accounted for 64% of its variance. Vertical lens tilt and decentration were also significantly correlated. It was also found that CDM increased by 3.5% per year, and part of this change can be attributed to the age-related increase in lens thickness.

Trypan blue staining of the anterior capsule under an air bubble with a modified cannula.

PubMed

Toprak, Ahmet Baris; Erkin, Esin Fatma; Guler, Cenap

2003-01-01

To attain good visibility of the anterior capsule in the advanced or white cataract, trypan blue 0.1% is used to stain the anterior capsule. The dye is usually injected under an air bubble. However, it is difficult to inject the dye properly due to capillary forces. An ordinary anterior chamber cannula was modified and its coverage area increased to facilitate the staining of the anterior capsule under an air bubble. The anterior capsule was stained properly by using the modified cannula in all of the cases.

Transient anterior subcapsular vacuolar change of the crystalline lens in patients after posterior chamber phakic intraocular lens implantation.

PubMed

Chung, Jin Kwon; Shin, Jin Hee; Lee, Sung Jin

2013-10-25

We present two cases of transient vacuolar changes in the anterior subcapsular space of the crystalline lens in patients after posterior chamber phakic intraocular lens implantation. Implantable collamer lenses (ICL) were implanted in healthy myopic patients. Vacuolar changes developed just after the irrigating procedure through the narrow space between the ICL and the crystalline lens. Slit-lamp examinations and spectral domain optical coherence tomography showed bleb-like lesions in the anterior subcapsular space of one eye in each case, though the lesions gradually improved without visual deterioration. Consequently, the lesions turned into a few anterior subcapsular small faint opacities. Direct irrigation of the narrow space confined by the ICL and the crystalline lens is at risk for the development of vacuolar changes in the crystalline lens. The observed spontaneous reversal indicates that surgeons should not rush to surgical intervention but rather opt for close follow over several weeks.

Dynamic gonioscopy using optical coherence tomography.

PubMed

Matonti, Frederic; Chazalon, Elodie; Trichet, Elodie; Khaled, El Samak; Denis, Danièle; Hoffart, Louis

2012-01-01

To describe the use of anterior segment optical coherence tomography (AS-OCT) in studying the dynamic changes of the anterior chamber angle by corneal indentation. In a prospective observational study, the anterior segments of 21 eyes were imaged using AS-OCT. After the initial scan, a second scan was executed on the same areas with a central corneal indentation. An evaluation of the reopening of the angle and its measurement were performed. With AS-OCT, the indirect signs were accurate enough to guide the diagnosis in all plateau iris confirmed by ultrabiomicroscopy. The angle widths were significantly increased after indentation. This method would appear to offer a convenient and rapid method of assessing the configuration of the anterior chamber; it may help during the routine clinical assessment and treatment of patients with narrow or closed angles, particularly when gonioscopy is difficult to interpret. Copyright 2012, SLACK Incorporated.

Scheimpflug imaging in anterior megalophthalmos

PubMed Central

Nemeth, Gabor; Hassan, Ziad; Berta, Andras; Modis, Laszlo

2013-01-01

We report an anterior megalophthalmos case with decreased corneal thickness and show the findings using Scheimpflug imaging. A 25-year-old male was diagnosed with anterior megalophthalmos. In both eyes, enlarged corneal length was measured. Beside a comparatively good visual acuity, a thin but clear cornea, a fairly deep anterior chamber, and central lens opacity were found. Scheimpflug images were taken using Pentacam HR. Scheimpflug-based imaging can provide us new data at the examination of this syndrome affecting the whole anterior segment. PMID:23275220

Scheimpflug imaging in anterior megalophthalmos.

PubMed

Nemeth, Gabor; Hassan, Ziad; Berta, Andras; Modis, Laszlo

2013-01-01

We report an anterior megalophthalmos case with decreased corneal thickness and show the findings using Scheimpflug imaging. A 25-year-old male was diagnosed with anterior megalophthalmos. In both eyes, enlarged corneal length was measured. Beside a comparatively good visual acuity, a thin but clear cornea, a fairly deep anterior chamber, and central lens opacity were found. Scheimpflug images were taken using Pentacam HR. Scheimpflug-based imaging can provide us new data at the examination of this syndrome affecting the whole anterior segment.

INTRAOCULAR LENS SCAFFOLD TO PREVENT INTRAOCULAR FOREIGN BODY SLIPPAGE.

PubMed

Agarwal, Amar; Ashok Kumar, Dhivya; Agarwal, Athiya

2017-01-01

To report the application of intraocular lens (IOL) scaffold technique in intraocular foreign body (IOFB) removal. Patient with IOFB in posterior segment is included. The IOFB is retrieved from the posterior segment (pars plana vitrectomy and exteriorization of the IOFB from the retinal surface using an intravitreal forceps via the posterior capsulotomy) and placed on the iris. A three-piece posterior chamber IOL is placed in the sulcus via the clear corneal incision. IOFB is then removed from the anterior chamber over the IOL by forceps. Metallic IOFB of 4 mm × 3 mm has been retrieved by IOL scaffold technique after rescuing it from the posterior segment. There has been no drop or slip of IOFB in the vitreous during removal. Posterior chamber IOL served as scaffold during IOFB removal from anterior chamber. The IOL scaffold maneuver has shown to prevent slippage by acting as a barrier between the IOFB and the vitreous.

Constant light rearing disrupts compensation to imposed- but not induced-hyperopia and facilitates compensation to imposed myopia in chicks

PubMed Central

Padmanabhan, Varuna; Shih, Jennifer; Wildsoet, Christine F.

2007-01-01

Purpose While rearing chicks in constant light (CL) inhibits anterior segment growth, these conditions also induce excessive enlargement of the vitreous chamber. The mechanisms underlying these effects are poorly understood although it has been speculated that the enlarged vitreous chambers are a product of emmetropization, a compensatory response to the altered anterior segments. We examined the ability of eyes to compensate to defocusing lenses in CL as a direct test of their ability to emmetropize. We also studied recovery responses, i.e. from lens-induced changes in CL as well as CL-induced changes alone or combined with lens-induced changes in eyes returned to normal diurnal lighting (NL). Methods Hatchling White-Leghorn chicks were reared in either CL or NL (control) lighting conditions (n = 36) for two weeks, with lenses of either +10 or −10 D power fitted to one eye of all chicks at the beginning of the second week. The lenses were removed at the end of the same week, at which time some CL chicks (n = 14) were shifted to NL, the rest of the chicks remaining in their respective original lighting conditiobns. Retinoscopy, IR photo-keratometry and high-frequency A-scan ultrasonography were used to track refractions, corneal radius of curvature and ocular axial dimensions respectively; data were collected on experimental days 0, 7, 9, 14 and 21. Results Under CL, eyes showed near normal, albeit slightly exaggerated responses to +10 D lenses while the response to −10 D lenses was disrupted. With +10 D lenses, lens-wearing eyes became more hyperopic (RE), and had shorter vitreous chambers (VC) and optical axial lengths (OL) relative to their fellows by the end of the lens period (RE: +10.5 ± 1.5 D, CL, +8.25 ± 2.5 D, NL; VC: −0.363 ± 0.129 mm, CL; −0.306 ± 0.110 mm, NL; OL: -0.493 ± 0.115 mm, CL, −0.379 ± 0.106 mm, NL (mean interocular difference ± SD). With −10 D lenses, the NL group showed a myopic shift in RE and increased elongation of both VC depth and OL (RE: −10.75 ± 2.0 D; VC depth: 0.554 ± 0.097 mm; OL: 0.746 ± 0.166 mm), while the CL group showed a small hyperopic shift in RE (+4.0 ± 6.0 D). Nonetheless, CL eyes were able to recover from lens-induced hyperopia, whether they were left in CL or returned to NL. One week of exposure to NL was sufficient to reverse the effects of 2 weeks of CL on anterior and vitreous chamber dimensions. Conclusion CL impairs emmetropization. Specifically, it disrupts compensation to lens-imposed hyperopia but not imposed myopia. However, CL eyes are able to recover from lens-induced hyperopia, suggesting that the mechanisms underlying the compensatory responses to defocusing lenses are different from those involved in recovery responses. The ocular growth effects of CL on young eyes are reversible under NL. PMID:17512028

Variable-Depth Liner Evaluation Using Two NASA Flow Ducts

NASA Technical Reports Server (NTRS)

Jones, M. G.; Nark, D. M.; Watson, W. R.; Howerton, B. M.

2017-01-01

Four liners are investigated experimentally via tests in the NASA Langley Grazing Flow Impedance Tube. These include an axially-segmented liner and three liners that use reordering of the chambers. Chamber reordering is shown to have a strong effect on the axial sound pressure level profiles, but a limited effect on the overall attenuation. It is also shown that bent chambers can be used to reduce the liner depth with minimal effects on the attenuation. A numerical study is also conducted to explore the effects of a planar and three higher-order mode sources based on the NASA Langley Curved Duct Test Rig geometry. A four-segment liner is designed using the NASA Langley CDL code with a Python-based optimizer. Five additional liner designs, four with rearrangements of the first liner segments and one with a redistribution of the individual chambers, are evaluated for each of the four sources. The liner configuration affects the sound pressure level profile much more than the attenuation spectra for the planar and first two higher-order mode sources, but has a much larger effect on the SPL profiles and attenuation spectra for the last higher-order mode source. Overall, axially variable-depth liners offer the potential to provide improved fan noise reduction, regardless of whether the axially variable depths are achieved via a distributed array of chambers (depths vary from chamber to chamber) or a group of zones (groups of chambers for which the depth is constant).

Vergence analysis reveals the influence of axial distances on accommodation with age and axial ametropia.

PubMed

Davies, Leon N; Dunne, Mark C M; Gibson, George A; Wolffsohn, James S

2010-07-01

Despite numerous investigations, the aetiology and mechanism of accommodation and presbyopia remains equivocal. Using Gaussian first-order ray tracing calculations, we examine the contribution that ocular axial distances make to the accommodation response. Further, the influence of age and ametropia are also considered. The data show that all changes in axial distances during accommodation reduce the accommodation response, with the reduction in anterior chamber depth contributing most to this overall attenuation. Although the total power loss due to the changes in axial distances remained constant with increasing age, hyperopes exhibited less accommodation than myopes. The study, therefore, enhances our understanding of biometric accommodative changes and demonstrates the utility of vergence analysis in the assessment of accommodation.

Incision integrity and postoperative outcomes after microcoaxial phacoemulsification performed using 2 incision-dependent systems.

PubMed

Vasavada, Vaishali; Vasavada, Abhay R; Vasavada, Viraj A; Srivastava, Samaresh; Gajjar, Devarshi U; Mehta, Siddharth

2013-04-01

To compare incision integrity and clinical outcomes of 2 microcoaxial phacoemulsification systems. Iladevi Cataract & IOL Research Centre, Ahmedabad, India. Prospective randomized clinical trial. Eyes were randomized to have phacoemulsification using a 1.8 mm clear corneal incision (CCI) system (Group 1, Stellaris system) or a 2.2 mm CCI system (Group 2, Intrepid Infiniti system). Incision enlargement at end of surgery was measured. At the conclusion of surgery, trypan blue was applied over the conjunctival surface, anterior chamber aspirate withdrawn, and ingress into anterior chamber measured. Postoperative observations included evaluation of the CCI using anterior segment optical coherence tomography (AS-OCT), change in central corneal thickness (CCT), and anterior segment inflammation at 1 day, 1 week, and 1 month and endothelial cell loss and surgically induced astigmatism (SIA) at 3 months. Incision enlargement (P<.001) and trypan blue ingress in the anterior chamber (mean 1.7 log units ± 0.6 [SD] versus 3.8 ± 0.6 log units, P<.001) was significantly greater in Group 1 (n = 50) than in Group 2 (n = 50). On AS-OCT, endothelial misalignment and gaping were more frequent in Group 1 at 1 day (P=.001) and 1 week (P=.018). There were no significant differences in SIA, change in CCT, endothelial cell loss, or anterior segment inflammation (P>.05). At the end of surgery, it is not the initial incision size alone but also the distortion of the incision during subsequent stages of surgery that determine the integrity of the CCI. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Spontaneous dislocation of a crystalline lens to the anterior chamber with pupillary block glaucoma in Noonan Syndrome: a case report.

PubMed

Mukhopadhyaya, Udayaditya; Chakraborti, Chandana; Mondal, Anindita; Pattyanayak, Ujjal; Agarwal, Rajesh Kumar; Tripathi, Partha

2014-01-01

We report a 13-year-old child with Noonan Syndrome who developed spontaneous dislocation of the crystalline lens in anterior chamber leading to pupillary block glaucoma in the left eye and subluxation of lens in right eye. Intracapsular extraction of the dislocated lens was done in the left eye. Prompt diagnosis and management is needed in such cases to avoid glaucoma and corneal endothelial cell damage. We could not find any such case after thorough Medline search.

Changes in Anterior Segment Morphology and Predictors of Angle Widening after Laser Iridotomy in South Indian Eyes.

PubMed

Zebardast, Nazlee; Kavitha, Srinivasan; Krishnamurthy, Palaniswamy; Friedman, David S; Nongpiur, Monisha E; Aung, Tin; Quigley, Harry A; Ramulu, Pradeep Y; Venkatesh, Rengaraj

2016-12-01

To compare anterior segment optical coherence tomography (ASOCT) angle morphology before and after laser peripheral iridotomy (LPI) in a cohort of South Indian subjects with primary angle-closure suspect (PACS) or primary angle-closure/primary angle-closure glaucoma (PAC/PACG) and to examine baseline parameters associated with angle widening. Prospective observational study. A total of 244 subjects aged ≥30 years with PACS or PAC/PACG in at least 1 eye. The ASOCT images and angle gonioscopic grades were analyzed for all subjects at baseline and 2 weeks after LPI. Multivariable linear and logistic regression models were used to determine predictors of angle widening (change in mean angle opening distance [AOD750]) and angle opening (all 4 quadrants with trabecular meshwork [TM] visible on gonioscopy after LPI). Change in ASOCT parameters with LPI and baseline predictors of angle widening. Laser peripheral iridotomy resulted in angle widening on ASOCT with significant increases in AOD750, angle recess area, and trabecular iris surface area (P < 0.05 for all). Gonioscopically, 44.7% of all subjects had open angles in all 4 quadrants after LPI, with a greater percentage of angles open in the PACS group compared with the PAC/PACG group (52.4% vs. 36.4%; P = 0.01). In multivariable regression analyses, greater postoperative angle widening as defined by change in AOD750 was associated with shorter baseline AOD750 and axial length, and greater baseline anterior chamber depth, iris curvature, and lens vault (P ≤ 0.002 for all). Gonioscopic angle opening after LPI was more common with wider baseline angle width (modified Shaffer grade) and lower cup-to-disc ratio (P < 0.001 for both). In a South Indian population with PACS or PAC/PACG, LPI results in significant anterior chamber angle widening seen on both ASOCT and gonioscopy, although some degree of persistent iridotrabecular contact was present in approximately half of PACS eyes and approximately two thirds of PAC/PACG eyes on gonioscopy. The greatest widening by ASOCT was observed in eyes with features most consistent with greater baseline pupillary block. Copyright © 2016 American Academy of Ophthalmology. All rights reserved.

Comparison of ultrasound biomicroscopy and ultrasonographic parameters in eyes with phacomorphic glaucoma and eyes with mature cataract.

PubMed

Subbiah, Sujata; Thomas, Philip A; Nelson Jesudasan, C A

2017-08-01

To compare data on anatomical and biometric parameters, and their combination, obtained by using ultrasound biomicroscopy (UBM) and A-scan in eyes with phacomorphic glaucoma (PG) and eyes with mature cataract and to determine differences that may predispose to development of PG. Eighty patients (80 eyes) were enrolled in this cross-sectional study. Anterior chamber parameters, namely anterior chamber depth (ACD), angle-opening distance (AOD), iris-lens contact distance (ILCD), and trabecular-ciliary process distance (TCPD), among other parameters, were assessed by UBM (35 MHz), while axial length (AL) and lenticular thickness (LT) were determined by A-scan biometry. Absolute lenticular position (ALP) and relative lenticular position (RLP) were also compared. The mean AL of eyes with PG was less (P = 0.64) than the mean AL of eyes with mature cataract. The mean ILCD value in eyes with PG (1.30 ± 0.78 mm) was significantly higher (P = 0.0015) than that in eyes with mature cataract (0.86 ± 0.32 mm). The mean AOD value in eyes with PG (0.15 ± 0.10 mm) was significantly lower (P < 0.0001) than that in eyes with mature cataract (0.23 ± 0.06 mm); similarly, the mean RLP value in eyes with PG (0.20 ± 0.02) was significantly lower (P < 0.0001) than that in eyes with mature cataract (0.17 ± 0.02). TCPD showed negative correlation with LT r = -0.514; P = 0.017, r 2  = 0.264, in eyes with phacomorphic glaucoma and mature cataracts showed significant negative correlation of ILCD with AL (r = -0.575; P = 0.025, r 2  = 0.330). The results of UBM examination suggest that there are multiple mechanisms underlying the pathophysiology of PG, namely crowding of the anterior segment, increased iris-lens contact distance, and a more pronounced anterior shift of the lens. Simultaneous evaluation of anatomic and biometric parameters can improve diagnostic accuracy in predicting cases at risk for PG.

Effect of counting chamber depth on the accuracy of lensless microscopy for the assessment of boar sperm motility.

PubMed

Soler, Carles; Picazo-Bueno, José Á; Micó, Vicente; Valverde, Anthony; Bompart, Daznia; Blasco, Francisco J; Álvarez, Juan G; García-Molina, Almudena

2018-05-04

Sperm motility is one of the most significant parameters in the prediction of male fertility. Until now, both motility analysis using an optical microscope and computer-aided sperm analysis (CASA-Mot) entailed the use of counting chambers with a depth to 20µm. Chamber depth significantly affects the intrinsic sperm movement, leading to an artificial motility pattern. For the first time, laser microscopy offers the possibility of avoiding this interference with sperm movement. The aims of the present study were to determine the different motility patterns observed in chambers with depths of 10, 20 and 100µm using a new holographic approach and to compare the results obtained in the 20-µm chamber with those of the laser and optical CASA-Mot systems. The ISAS®3D-Track results showed that values for curvilinear velocity (VCL), straight line velocity, wobble and beat cross frequency were higher for the 100-µm chambers than for the 10- and 20-µm chambers. Only VCL showed a positive correlation between chambers. In addition, Bayesian analysis confirmed that the kinematic parameters observed with the 100-µm chamber were significantly different to those obtained using chambers with depths of 10 and 20µm. When an optical analyser CASA-Mot system was used, all kinematic parameters, except VCL, were higher with ISAS®3D-Track, but were not relevant after Bayesian analysis. Finally, almost three different three-dimensional motility patterns were recognised. In conclusion, the use of the ISAS®3D-Track allows for the analysis of the natural three-dimensional pattern of sperm movement.

Hong's grading for evaluating anterior chamber angle width.

PubMed

Kim, Seok Hwan; Kang, Ja Heon; Park, Ki Ho; Hong, Chul

2012-11-01

To compare Hong's grading method with anterior segment optical coherence tomography (AS-OCT), gonioscopy, and the dark-room prone-position test (DRPT) for evaluating anterior chamber width. The anterior chamber angle was graded using Hong's grading method, and Hong's angle width was calculated from the arctangent of Hong's grades. The correlation between Hong's angle width and AS-OCT parameters was analyzed. The area under the receiver operating characteristic curve (AUC) for Hong's grading method when discriminating between narrow and open angles as determined by gonioscopy was calculated. Correlation analysis was performed between Hong's angle width and intraocular pressure (IOP) changes determined by DRPT. A total of 60 subjects were enrolled. Of these subjects, 53.5 % had a narrow angle. Hong's angle width correlated significantly with the AS-OCT parameters (r = 0.562-0.719, P < 0.01). A Bland-Altman plot showed relatively good agreement between Hong's angle width and the angle width obtained by AS-OCT. The ability of Hong's grading method to discriminate between open and narrow angles was good (AUC = 0.868, 95 % CI 0.756-0.942). A significant linear correlation was found between Hong's angle width and IOP change determined by DRPT (r = -0.761, P < 0.01). Hong's grading method is useful for detecting narrow angles. Hong's grading correlated well with AS-OCT parameters and DRPT.

Anterior segment sparing to reduce charged particle radiotherapy complications in uveal melanoma

NASA Technical Reports Server (NTRS)

Daftari, I. K.; Char, D. H.; Verhey, L. J.; Castro, J. R.; Petti, P. L.; Meecham, W. J.; Kroll, S.; Blakely, E. A.; Chatterjee, A. (Principal Investigator)

1997-01-01

PURPOSE: The purpose of this investigation is to delineate the risk factors in the development of neovascular glaucoma (NVG) after helium-ion irradiation of uveal melanoma patients and to propose treatment technique that may reduce this risk. METHODS AND MATERIALS: 347 uveal melanoma patients were treated with helium-ions using a single-port treatment technique. Using univariate and multivariate statistics, the NVG complication rate was analyzed according to the percent of anterior chamber in the radiation field, tumor size, tumor location, sex, age, dose, and other risk factors. Several University of California San Francisco-Lawrence Berkeley National Laboratory (LBNL) patients in each size category (medium, large, and extralarge) were retrospectively replanned using two ports instead of a single port. By using appropriate polar and azimuthal gaze angles or by treating patients with two ports, the maximum dose to the anterior segment of the eye can often be reduced. Although a larger volume of anterior chamber may receive a lower dose by using two ports than a single port treatment. We hypothesize that this could reduce the level of complications that result from the irradiation of the anterior chamber of the eye. Dose-volume histograms were calculated for the lens, and compared for the single and two-port techniques. RESULTS: NVG developed in 121 (35%) patients. The risk of NVG peaked between 1 and 2.5 years posttreatment. By univariate and multivariate analysis, the percent of lens in the field was strongly correlated with the development of NVG. Other contributing factors were tumor height, history of diabetes, and vitreous hemorrhage. Dose-volume histogram analysis of single-port vs. two-port techniques demonstrate that for some patients in the medium and large category tumor groups, a significant decrease in dose to the structures in the anterior segment of the eye could have been achieved with the use of two ports. CONCLUSION: The development of NVG after helium-ion irradiation is correlated to the amount of lens, anterior chamber in the treatment field, tumor height, proximity to the fovea, history of diabetes, and the development of vitreous hemorrhage. Although the influence of the higher LET deposition of helium-ions is unclear, this study suggests that by reducing the dose to the anterior segment of the eye may reduce the NVG complications. Based on this retrospective analysis of LBNL patients, we have implemented techniques to reduce the amount of the anterior segment receiving a high dose in our new series of patients treated with protons using the cyclotron at the UC Davis Crocker Nuclear Laboratory (CNL).

Optical coherence tomography in anterior segment imaging

PubMed Central

Kalev-Landoy, Maya; Day, Alexander C.; Cordeiro, M. Francesca; Migdal, Clive

2008-01-01

Purpose To evaluate the ability of optical coherence tomography (OCT), designed primarily to image the posterior segment, to visualize the anterior chamber angle (ACA) in patients with different angle configurations. Methods In a prospective observational study, the anterior segments of 26 eyes of 26 patients were imaged using the Zeiss Stratus OCT, model 3000. Imaging of the anterior segment was achieved by adjusting the focusing control on the Stratus OCT. A total of 16 patients had abnormal angle configurations including narrow or closed angles and plateau irides, and 10 had normal angle configurations as determined by prior full ophthalmic examination, including slit-lamp biomicroscopy and gonioscopy. Results In all cases, OCT provided high-resolution information regarding iris configuration. The ACA itself was clearly visualized in patients with narrow or closed angles, but not in patients with open angles. Conclusions Stratus OCT offers a non-contact, convenient and rapid method of assessing the configuration of the anterior chamber. Despite its limitations, it may be of help during the routine clinical assessment and treatment of patients with glaucoma, particularly when gonioscopy is not possible or difficult to interpret. PMID:17355288

Biocompatibility of Genipin and Glutaraldehyde Cross-Linked Chitosan Materials in the Anterior Chamber of the Eye

PubMed Central

Lai, Jui-Yang

2012-01-01

Chitosan is a naturally occurring cationic polysaccharide and has attracted much attention in the past decade as an important ophthalmic biomaterial. We recently demonstrated that the genipin (GP) cross-linked chitosan is compatible with human retinal pigment epithelial cells. The present work aims to further investigate the in vivo biocompatibility of GP-treated chitosan (GP-chi group) by adopting the anterior chamber of a rabbit eye model. The glutaraldehyde (GTA) cross-linked samples (GTA-chi group) were used for comparison. The 7-mm-diameter membrane implants made from either non-cross-linked chitosan or chemically modified materials with a cross-linking degree of around 80% were inserted in the ocular anterior chamber for 24 weeks and characterized by slit-lamp and specular microscopic examinations, intraocular pressure measurements, and corneal thickness measurements. The interleukin-6 expressions at mRNA level were also detected by quantitative real-time reverse transcription polymerase chain reaction. Results of clinical observations showed that the overall ocular scores in the GTA-chi groups were relatively high. In contrast, the rabbits bearing GP-chi implants in the anterior chamber of the eye exhibited no signs of ocular inflammation. As compared to the non-cross-linked counterparts, the GP-chi samples improved the preservation of corneal endothelial cell density and possessed better anti-inflammatory activities, indicating the benefit action of the GP cross-linker. In summary, the intracameral tissue response to the chemically modified chitosan materials strongly depends on the selection of cross-linking agents. PMID:23109832

A methodology based on the "anterior chamber of rabbit eyes" model for noninvasively determining the biocompatibility of biomaterials in an immune privileged site.

PubMed

Lu, Pei-Lin; Lai, Jui-Yang; Tabata, Yasuhiko; Hsiue, Ging-Ho

2008-07-01

In this study, a novel methodology based on the anterior chamber of rabbit eyes model was developed to evaluate the in vivo biocompatibility of biomaterials in an immune privileged site. The 7-mm-diameter membrane implants made from either a biological tissue material (amniotic membrane, AM group) or a biomedical polymeric material (gelatin, GM group) were inserted in rabbit anterior chamber for 36 months and characterized by biomicroscopic examinations, intraocular pressure measurements, and corneal thickness measurements. The noninvasive ophthalmic parameters were scored to provide a quantitative grading system. In this animal model, both AM and GM implants were visible in an ocular immune privileged site during clinical observations. The implants of the AM group appeared as soft tissue patches and have undergone a slow dissolution process resulting in a partial reduction of their size. Additionally, the AM implants did not induce any foreign body reaction or change in ocular tissue response for the studied period. By contrast, in the GM groups, significant corneal edema, elevated intraocular pressure, and increased corneal thickness were noted in the early postoperative phase (within 3 days), but resolved rapidly with in vivo dissolution of the gelatin. The results from the ocular grading system showed that both implants had good long-term biocompatibility in an ocular immune privileged site for up to 3 years. It is concluded that the anterior chamber of rabbit eyes model is an efficient method for noninvasively determining the immune privileged tissue/biomaterial interactions. (c) 2007 Wiley Periodicals, Inc.

Acoustic Panel Liner for an Engine Nacelle

NASA Technical Reports Server (NTRS)

Nark, Douglas M. (Inventor); Ayle, Earl (Inventor); Jones, Michael G. (Inventor); Ichihashi, Fumitaka (Inventor)

2016-01-01

An acoustic panel liner includes a face sheet, back plate, and liner core positioned there-between, which may be used in an engine nacelle. Elongated chambers contain variable amounts of septa at a calibrated depth or depths. The septa may have varying DC flow resistance. The chambers may have a hexagonal or other polygonal cross sections. The septa, such as mesh caps, may be bonded to an inner wall of a corresponding chamber. The insertion depths may be the same or different. If different, the pattern of distribution of the depths may be randomized.

Trocar anterior chamber maintainer: Improvised infusion technique.

PubMed

Agarwal, Amar; Narang, Priya; Kumar, Dhivya A; Agarwal, Ashvin

2016-02-01

We present an improvised technique of infusion that uses a trocar cannula as an anterior chamber maintainer (ACM). Although routinely used in posterior segment surgery, the trocar cannula has been infrequently used in complex anterior segment procedures. The trocar ACM creates a transconjunctival biplanar wound of appropriate size that is self-sealing and overcomes the shortcomings of an ACM, such as spontaneous extrusion and forced introduction into the eye from variability in the size of the corneal paracentesis incision. Constant infusion inflow through the trocar ACM is used to maintain positive intraocular pressure through a self-sealing sclerotomy incision at the limbus. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Uveal effusion following acute primary angle-closure: a retrospective case series

PubMed Central

Yang, Jian-Gang; Li, Jian-Jun; Tian, Hua; Li, Yan-Hong; Gong, Yu-Jing; Su, An-Le; He, Na

2017-01-01

AIM To evaluate the morphological changes in anterior segment in Chinese patients with uveal effusion (UE) after the attack of acute primary angle-closure (APAC) using ultrasound biomicroscopy (UBM), and to assess the clinical course and prognosis of the disease. METHODS In a retrospective case series, 26 eyes in 26 consecutive patients diagnosed with UE after the treatment of intraocular pressure (IOP)-lowering medication for the attack of APAC were enrolled. The unaffected fellow eyes served as controls. The morphological changes were observed by ultrasonography, slit lamp microscopy and gonioscopy. UBM was used to assess the degree and extent of effusion based on the analysis of parameters associated with UE. RESULTS The mean IOP was 9.2 (SD 2.1) mm Hg at the diagnosis of UE after IOP-lowering medication, while 14.1 (SD, 2.6) mm Hg in the fellow eyes (P=0.000). The anterior chamber depth (ACD) (P=0.000), angle opening distance at 500 µm (AOD500) (P<0.01) and anterior chamber angle (ACA) (P<0.05) were decreased significantly, while ciliary body thickness (CBT) (P<0.05) increased significantly in UE eyes. UE grade analysis showed 7 eyes in grade 1, 9 eyes in grade 2, and 10 eyes in grade 3. Quadrant scores were performed of 4 eyes in 1 quadrant, 3 eyes in 3 quadrants, and 19 eyes in 4 quadrants. There was the positive correlation between grade and quadrant score (r=0.644, P=0.000). The effusion on all eyes were recovered after medication, which mean IOP was 13.9 (SD, 2.8) mm Hg. CONCLUSION UE is a frequent complication in Chinese patients after the attack of APAC, partially associated with hypotony. The severity of UE is correlation with height of effusion, extent of detachment, and shallower ACD. PMID:28393032

Anterior segment biometry using ultrasound biomicroscopy and the Artemis-2 very high frequency ultrasound scanner

PubMed Central

Al-Farhan, Haya M; AlMutairi, Reem N

2013-01-01

Purpose To compare the precision of anterior chamber angle (ACA) and anterior chamber depth (ACD) measurements taken with ultrasound biomicroscopy (UBM) and the Artemis-2 Very High Frequency Ultrasound Scanner (VHFUS) in normal subjects. Design Prospective study. Methods We randomly selected one eye from each of 59 normal subjects in this study. Two subjects dropped out of the study; the associated data were excluded from analysis. ACA and ACD measurements were obtained using the VHFUS and the UBM. The results were compared statistically using repeated-measures analysis of variance for the intraobserver repeatability, unpaired t-test, and limits of agreement. Results The average ACA values for the UBM and the VHFUS (±standard deviation) were 41.83° ± 5.03° and 33.36° ± 6.03°, respectively. The average ACD values were 2.96 ± 0.34 mm and 2.87 ± 0.31 mm. The intraobserver repeatability analysis of variance P-values for ACA and ACD measurements using UBM were 0.10 and 0.68, respectively; for the Artemis-2 VHFUS, the respective values were 0.68 and 0.09. The difference in ACA measurements was statistically significant (t = 8.41; P < 0.0001), while the difference in ACD values was not (t = 1.51; P < 0.13). The mean ACA difference was 8.50° ± 2.50°, and the limits of agreement were +13.30° to −3.60°. The mean ACD difference was 0.09 ± 0.27 mm, and the limits of agreement ranged from 0.61 mm to −0.43 mm. The mean difference percentage of ACD was 3.1% for both instruments. Conclusion In case of the ACD, both instruments can be used interchangeably; however, with the ACA instruments, they cannot be used interchangeably. PMID:23345968

[Evaluation of free radical quantity in the anterior chamber following femtosecond laser-assisted capsulotomy].

PubMed

Tóth, Gábor; Sándor, Gábor László; Kleiner, Dénes; Szentmáry, Nóra; Kiss, Huba J; Blázovics, Anna; Nagy, Zoltán Zsolt

2016-11-01

Femtosecond laser is a revolutionary, innovative treatment method used in cataract surgery. To evaluate free radical quantity in the anterior chamber of the eye, during femtosecond laser assisted capsulotomy, in a porcine eye model. Seventy fresh porcine eyes were collected within 2 hours post mortem, were transported at 4 ºC and treated within 7 hours. Thirty-five eyes were used as control and 35 as femtosecond laser assisted capsulotomy group. A simple luminol-dependent chemiluminescence method was used to measure the total scavenger capacity in the aqueous humour, as an indicator of free radical production. The emitted photons were expressed in relative light unit %. The relative light unit % was lower in the control group (median 1%, interquartile range [0.4-3%]) than in the femtosecond laser assisted capsulotomy group (median 4.4%, interquartile range [1.5%-21%]) (p = 0.01). Femtosecond laser assisted capsulotomy decreases the antioxidant defense of the anterior chamber, which refers to a significant free radical production during femtosecond laser assisted capsulotomy. Orv. Hetil., 2016, 157(47), 1880-1883.

Effects of aqueous humor hydrodynamics on human eye heat transfer under external heat sources.

PubMed

Tiang, Kor L; Ooi, Ean H

2016-08-01

The majority of the eye models developed in the late 90s and early 00s considers only heat conduction inside the eye. This assumption is not entirely correct, since the anterior and posterior chambers are filled aqueous humor (AH) that is constantly in motion due to thermally-induced buoyancy. In this paper, a three-dimensional model of the human eye is developed to investigate the effects AH hydrodynamics have on the human eye temperature under exposure to external heat sources. If the effects of AH flow are negligible, then future models can be developed without taking them into account, thus simplifying the modeling process. Two types of external thermal loads are considered; volumetric and surface irradiation. Results showed that heat convection due to AH flow contributes to nearly 95% of the total heat flow inside the anterior chamber. Moreover, the circulation inside the anterior chamber can cause an upward shift of the location of hotspot. This can have significant consequences to our understanding of heat-induced cataractogenesis. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

SU-E-T-562: Scanned Percent Depth Dose Curve Discrepancy for Photon Beams with Physical Wedge in Place (Varian IX) Using Different Sensitive Volume Ion Chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, H; Sarkar, V; Rassiah-Szegedi, P

2014-06-01

Purpose: To investigate and report the discrepancy of scanned percent depth dose (PDD) for photon beams with physical wedge in place when using ion chambers with different sensitive volumes. Methods/Materials: PDD curves of open fields and physical wedged fields (15, 30, 45, and 60 degree wedge) were scanned for photon beams (6MV and 10MV, Varian iX) with field size of 5x5 and 10x10 cm using three common scanning chambers with different sensitive volumes - PTW30013 (0.6cm3), PTW23323 (0.1cm3) and Exradin A16 (0.007cm3). The scanning system software used was OmniPro version 6.2, and the scanning water tank was the Scanditronix Wellhoffermore » RFA 300.The PDD curves from the three chambers were compared. Results: Scanned PDD curves of the same energy beams for open fields were almost identical between three chambers, but the wedged fields showed non-trivial differences. The largest differences were observed between chamber PTW30013 and Exradin A16. The differences increased as physical wedge angle increased. The differences also increased with depth, and were more pronounced for 6MV beam. Similar patterns were shown for both 5x5 and 10x10 cm field sizes. For open fields, all PDD values agreed with each other within 1% at 10cm depth and within 1.62% at 20 cm depth. For wedged fields, the difference of PDD values between PTW30013 and A16 reached 4.09% at 10cm depth, and 5.97% at 20 cm depth for 6MV with 60 degree physical wedge. Conclusion: We observed a significant difference in scanned PDD curves of photon beams with physical wedge in place obtained when using different sensitive volume ion chambers. The PDD curves scanned with the smallest sensitive volume ion chamber showed significant difference from larger chamber results, beyond 10cm depth. We believe this to be caused by varying response to beam hardening by the wedges.« less

Simultaneous refraction measurement and OCT axial biometry of the eye during accommodation (Conference Presentation)

NASA Astrophysics Data System (ADS)

De Freitas, Carolina; Hernandez, Victor M.; Ruggeri, Marco; Durkee, Heather A.; Williams, Siobhan; Gregori, Giovanni; Ho, Arthur; Manns, Fabrice; Parel, Jean-Marie

2016-03-01

The purpose of this project is to design and evaluate a system that will enable objective assessment of the optical accommodative response in real-time while acquiring axial biometric information. The system combines three sub-systems which were integrated and mounted on a joystick x-y-z adjustable modified slit-lamp base to facilitate alignment and data acquisition: (1) a Shack-Hartmann wavefront sensor for dynamic refraction measurement, provided software calculates sphere, cylinder and axis values, (2) an extended-depth Optical Coherence Tomography (OCT) system using an optical switch records high-resolution cross-sectional images across the length of the eye, from which, dynamic axial biometry (corneal thickness, anterior chamber depth, crystalline lens thickness and vitreous depth) can be extracted, and (3) a modified dual-channel accommodation stimulus unit based on the Badal optometer for providing a step change in accommodative stimulus. The prototypal system is capable of taking simultaneous measurements of both the optical and the mechanical response of lens accommodation. These measurements can provide insight into correlating changes in lens shape with changes in lens power and ocular refraction and ultimately provide a more comprehensive understanding of accommodation, presbyopia and an objective assessment of presbyopia correction techniques.

SU-F-T-73: Experimental Determination of the Effective Point of Measurement in Electron Beams Using a Commercial Scintillation Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simiele, E; Smith, B; Culberson, W

2016-06-15

Purpose: The aim of this work was to determine experimentally the effective point of measurement (EPOM) in clinical electron beams for three cylindrical ionization chambers using a commercial scintillation detector as a reference detector. Methods: Percent depth dose (PDD) curves were measured using an Exradin W1 scintillation detector and were used as a representative PDD to water. Depth dose curves were measured with the Exradin A18, A1SL, and A28 ionization chambers. The raw ionization chamber curve data were corrected by the chamber fluence perturbation correction factor and restricted mass collisional stopping power ratio at each depth to obtain a percentmore » depth dose curve to the gas volume (PDDGV) of the detector. Ratios of the W1 PDD to the ion chamber PDDGV were calculated for each measurement depth. The W1 PDD curve was shifted by small depth increments, Δz, until the ratio of the W1 PDD to the ion chamber PDDGV was depth-independent (optimal Δz). A MATLAB routine was developed to determine the optimal Δz value. Results: The optimal Δz shift was used as an estimate of the EPOM for each chamber. The average calculated EPOM shifts (expressed as a fraction of the chamber cavity radius) for the A18, A1SL, and A28 ionization chambers were 0.21 ± 0.04, 0.10 ± 0.05, and 0.22 ± 0.03, respectively. Conclusion: The experimentally determined EPOM values for the A18 and A1SL in this work agreed with the simulated values of Muir and Rogers (MedPhys 2014). The results also indicate that the Exradin W1 scintillator is water equivalent for electron energies of 6 MeV, 9 MeV, 12 MeV, and 16 MeV. In addition, we confirmed that the AAPM TG51 recommended EPOM shift of 0.5 times the cavity radius is not accurate for the A18 and A1SL chambers.« less

Evaluation of circumferential angle closure using iridotrabecular contact index after laser iridotomy by swept-source optical coherence tomography.

PubMed

Cho, Hyun-Kyung; Ahn, Dongsub; Kee, Changwon

2017-05-01

To investigate the quantitative changes of circumferential angle closure after laser iridotomy (LI) using the iridotrabecular contact (ITC) index by Swept-Source optical coherence tomography (OCT). In this prospective observational study conducted in a hospital setting, 42 eyes of 36 patients (five males, 31 females) who underwent LI were included. The mean age was 65.00 ± 8.13 years old and the diagnosis included primary angle closure (PAC, 21 eyes), PAC suspect (16 eyes) and PAC glaucoma (five eyes). Optical coherence tomography (OCT) images were obtained pre-LI and at 1 week post-LI. In each image frame, the scleral spur (SS) and the ITC end-point were marked, from which the ITC index was calculated as a percentage of the angle closure across 360°. Measurements inspected before and after LI included: central anterior chamber depth (ACD), anterior chamber volume (ACV), lens vault (LV), nasal and temporal angle opening distance (AOD), angle recess area (ARA), trabecular-iris space area (TISA), trabecular-iris angle (TIA) at 500 μm and 750 μm from the SS and intraocular pressure (IOP). The ITC index and IOP decreased significantly after LI from 71.52 ± 26.29 to 35.31 ± 27.19 and from 20.64 ± 12.72 mmHg to 14.02 ± 3.49 mmHg, respectively (p < 0.001 and p < 0.001). Central ACD (1.94 ± 0.31 mm pre-LI) and LV (1.13 ± 0.32 mm pre-LI) did not show a significant change after LI (all p > 0.05), but ACV increased significantly after LI (p < 0.001). Most of the angle parameters except for nasal TIAs increased significantly after LI (all p < 0.05). The ITC index from patients with shallow anterior chamber angle showed a significant decrease after LI, but part of the angle closure was not relieved after LI. Other mechanisms besides pupillary block may play a role together in causing angle closure. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

An ocular cysticercosis in Bali, Indonesia caused by Taenia solium Asian genotype.

PubMed

Swastika, Kadek; Dewiyani, Cokorda I; Yanagida, Tetsuya; Sako, Yasuhiko; Sudarmaja, Made; Sutisna, Putu; Wandra, Toni; Dharmawan, Nyoman S; Nakaya, Kazuhiro; Okamoto, Munehiro; Ito, Akira

2012-06-01

An ocular cysticercosis case of a nine-year-old Balinese girl in Indonesia is reported. She presented with redness and pain in the left eye and showed a cysticercus in the anterior chamber in December 2010. Morphological feature of the cysticercus removed from the anterior chamber indicated that it was an immature cysticercus of Taenia species with no hooklets. However, mitochondrial DNA analysis using a piece of histopathological specimen revealed it a cysticercus of Taenia solium Asian genotype. Serology by immunoblot and ELISA highly specific to cysticercosis was negative. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Air Pump-Assisted Graft Centration, Graft Edge Unfolding, and Graft Uncreasing in Young Donor Graft Pre-Descemet Endothelial Keratoplasty.

PubMed

Jacob, Soosan; Narasimhan, Smita; Agarwal, Amar; Agarwal, Athiya; A I, Saijimol

2017-08-01

To assess an air pump-assisted technique for graft centration, graft edge unfolding, and graft uncreasing while performing pre-Descemet endothelial keratoplasty (PDEK) using young donor grafts. Continuous pressurized air infusion was used for graft centration, graft edge unfolding, and graft unwrinkling. Ten eyes of 10 patients underwent PDEK with donors aged below 40 years. In all eyes, the donor scrolled into tight scrolls. In all cases, the air pump-assisted technique was effective in positioning and centering the graft accurately and in straightening infolded graft edges and smoothing out graft creases and wrinkles. Endothelial cell loss was 38.6%. Postoperative best-corrected visual acuity at 6 months was 0.66 ± 0.25 in decimal equivalent. Continuous pressurized air infusion acted as a third hand providing a continuous pressure head that supported the graft and prevented graft dislocation as well as anterior chamber collapse during intraocular maneuvering. Adequate maneuvering space was available in all cases, and bleeding, if any, was tamponaded successfully in all cases. Although very young donor grafts may be used for PDEK, they are difficult to center and unroll completely before floating against host stroma. An air pump-assisted technique using continuous pressurized air infusion allows successful final graft positioning even with very young donor corneas. It thus makes surgery easier as several key steps are made easier to handle. It additionally helps in tamponading hemorrhage during peripheral iridectomy, increasing surgical space, preventing fluctuations in the anterior chamber depth, and promoting graft adherence.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asadi, Somayeh; Masoudi, Seyed Farhad, E-mail: masoudi@kntu.ac.ir; Shahriari, Majid

In ophthalmic brachytherapy dosimetry, it is common to consider the water phantom as human eye anatomy. However, for better clinical analysis, there is a need for the dose determination in different parts of the eye. In this work, a full human eye is simulated with MCNP-4C code by considering all parts of the eye, i.e., the lens, cornea, retina, choroid, sclera, anterior chamber, optic nerve, and bulk of the eye comprising vitreous body and tumor. The average dose in different parts of this full model of the human eye is determined and the results are compared with the dose calculatedmore » in water phantom. The central axes depth dose and the dose in whole of the tumor for these 2 simulated eye models are calculated as well, and the results are compared.« less

Pupillary Reconstruction and Outcome after Artificial Iris Implantation.

PubMed

Mayer, Christian S; Reznicek, Lukas; Hoffmann, Andrea E

2016-05-01

Patients with iris defects suffer from severe visual impairment, especially increased glare sensitivity and cosmetic disturbances. This constitutes a great psychological strain for those patients. Until recently, possible treatment options were iris print contact lenses, sunglasses, and simple iris prostheses. The aim of this study was to investigate structural and functional outcome parameters and patient satisfaction after implantation of this new artificial iris prosthesis. Prospective case series investigating functional results and patient satisfaction after surgical iris reconstruction. Thirty-seven consecutive patients with traumatic iris defects presenting from 2011 through 2014 underwent pupillary reconstruction with a new artificial iris implant at the Department of Ophthalmology, Technical University Munich. The custom-made, flexible silicone iris prosthesis ArtificialIris (HumanOptics, Erlangen, Germany) used in this study is a novel and innovative device in the surgical treatment of iris defects. Patients were examined before and after iris reconstruction with the iris implant placed in the ciliary sulcus. Change of best-corrected visual acuity (BCVA), intraocular pressure (IOP), pupillary aperture, glare, contrast sensitivity, endothelial cell density, anterior chamber depth, anterior chamber angle, and patient satisfaction were assessed. Thirty-two eyes of 32 patients (mean age, 52.9±16.0 years) were included. After implantation and during follow-up, BCVA and IOP did not change significantly (BCVA, 0.77±0.62 logarithm of the minimum angle of resolution [logMAR] preoperatively vs. 0.68±0.64 logMAR 1 month postoperatively [P = 0.792]; IOP, 14.94±3.55 mmHg preoperatively vs. 17.72±5.88 mmHg 1 month postoperatively [P = 0.197]). The pupillary aperture was reduced significantly (42.11±20.1 mm(2) to 8.7±0.3 mm(2); P < 0.001). Contrast sensitivity increased significantly (0.80±0.51 to 0.93±0.49; P = 0.014). Endothelial cell count revealed a significant decrease postoperatively (1949±716 per 1 mm(2) to 1841±689 per 1 mm(2); P = 0.003). Anterior chamber depth (4.03±1.06 mm preoperatively vs. 4.29±0.70 mm postoperatively; P = 0.186) and angle (43.2±13.5° preoperatively vs. 40.5±10.8° postoperatively; P = 0.772) showed no significant differences. Subjective impairment through glare (9.12±1.62 preoperatively vs. 3.07±2.29 postoperatively; P < 0.001) and cosmetic disturbance (6.33±3.21 preoperatively vs. 1.58±0.86 postoperatively; P < 0.001) improved significantly. Patient satisfaction with the overall result was 8.91±1.51 of 10 points on an analog scale. The implantation of the artificial iris is a new and effective therapeutic option for the treatment of distinctive traumatic iris defects and results in an individual, aesthetically appealing, and good functional outcome in addition to high patient satisfaction. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Comparative Study of Anterior Eye Segment Measurements with Spectral Swept-Source and Time-Domain Optical Coherence Tomography in Eyes with Corneal Dystrophies

PubMed Central

Teper, Sławomir J.; Janiszewska, Dominika A.; Lyssek-Boron, Anita; Dobrowolski, Dariusz; Koprowski, Robert; Wylegala, Edward

2015-01-01

Purpose. To compare anterior eye segment measurements and morphology obtained with two optical coherence tomography systems (TD OCT, SS OCT) in eyes with corneal dystrophies (CDs). Methods. Fifty healthy volunteers (50 eyes) and 54 patients (96 eyes) diagnosed with CD (epithelial basement membrane dystrophy, EBMD = 12 eyes; Thiel-Behnke CD = 6 eyes; lattice CD TGFBI type = 15 eyes; granular CD type 1 = 7 eyes, granular CD type 2 = 2 eyes; macular CD = 23 eyes; and Fuchs endothelial CD = 31 eyes) were recruited for the study. Automated and manual central corneal thickness (aCCT, mCCT), anterior chamber depth (ACD), and nasal and temporal trabecular iris angle (nTIA, tTIA) were measured and compared with Bland-Altman plots. Results. Good agreement between the TD and SS OCT measurements was demonstrated for mCCT and aCCT in normal individuals and for mCCT in the CDs group. The ACD, nTIA, and tTIA measurements differed significantly in both groups. TBCD, LCD, and FECD caused increased CCT. MCD caused significant corneal thinning. FECD affected all analyzed parameters. Conclusions. Better agreement between SS OCT and TD OCT measurements was demonstrated in normal individuals compared to the CDs group. OCT provides comprehensive corneal deposits analysis and demonstrates the association of CD with CCT, ACD, and TIA measurements. PMID:26457303

Comparative Study of Anterior Eye Segment Measurements with Spectral Swept-Source and Time-Domain Optical Coherence Tomography in Eyes with Corneal Dystrophies.

PubMed

Nowinska, Anna K; Teper, Sławomir J; Janiszewska, Dominika A; Lyssek-Boron, Anita; Dobrowolski, Dariusz; Koprowski, Robert; Wylegala, Edward

2015-01-01

To compare anterior eye segment measurements and morphology obtained with two optical coherence tomography systems (TD OCT, SS OCT) in eyes with corneal dystrophies (CDs). Fifty healthy volunteers (50 eyes) and 54 patients (96 eyes) diagnosed with CD (epithelial basement membrane dystrophy, EBMD = 12 eyes; Thiel-Behnke CD = 6 eyes; lattice CD TGFBI type = 15 eyes; granular CD type 1 = 7 eyes, granular CD type 2 = 2 eyes; macular CD = 23 eyes; and Fuchs endothelial CD = 31 eyes) were recruited for the study. Automated and manual central corneal thickness (aCCT, mCCT), anterior chamber depth (ACD), and nasal and temporal trabecular iris angle (nTIA, tTIA) were measured and compared with Bland-Altman plots. Good agreement between the TD and SS OCT measurements was demonstrated for mCCT and aCCT in normal individuals and for mCCT in the CDs group. The ACD, nTIA, and tTIA measurements differed significantly in both groups. TBCD, LCD, and FECD caused increased CCT. MCD caused significant corneal thinning. FECD affected all analyzed parameters. Better agreement between SS OCT and TD OCT measurements was demonstrated in normal individuals compared to the CDs group. OCT provides comprehensive corneal deposits analysis and demonstrates the association of CD with CCT, ACD, and TIA measurements.

Ultrasonography and optical low-coherence interferometry compared in the chicken eye.

PubMed

Penha, Alexandra Marcha; Burkhardt, Eva; Schaeffel, Frank; Feldkaemper, Marita P

2012-06-01

To compare ocular biometry [anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), and axial length (AL)] using A-scan ultrasonography and optical low-coherence interferometry (OLCI) in the chicken eye. Two-week-old chicks (n = 42) were measured. Bland-Altman plots and repeatability and correlation analyses were calculated for both methods. There was a high correlation between both methods for ACD (r = 0.6144, p < 0.0001), VCD (r = 0.9595, p < 0.0001), and AL (r = 0.9290, p < 0.0001) but not for LT (r = 0.1604, p = 0.144). Measurements by OLCI were more consistent (smaller coefficients of variation and higher intraclass correlation). Bland-Altman plots showed that ultrasound provided larger values for LT, VCD, and AL but not for ACD [differences between ultrasound and OLCI (mean ± SD): ACD = -0.11 ± 0.12 mm; LT = 0.10 ± 0.09 mm; VCD = 0.25 ± 0.08 mm; AL = 0.50 ± 0.16 mm]. A high correlation between both techniques was found for three of the four parameters (ACD, VCD, and AL). However, as the absolute values were different, both techniques cannot replace each other mainly because (1) one is non-contact and the other contact and can induce a minor indentation of the cornea and (2) each device uses different types of waves that cross the ocular interfaces differently. While consistency and repeatability were better by OLCI, a disadvantage is that, different from humans, it can only be used in anesthetized chicks.

Height, weight, body mass index and ocular biometry in patients with sickle cell disease.

PubMed

Osuobeni, Ebi Peter; Okpala, Iheanyi; Williamson, Tom H; Thomas, Peter

2009-03-01

To investigate the effects of physical size on refractive error and the dimensions of optical components in sickle cell disease (SCD). The design was cross sectional. Height and weight of adult patients suffering from SCD were measured, and body mass index (BMI) was calculated. Anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD) and axial length (AL) were measured using A-scan ultrasonography. Corneal radius of curvature (CR) was measured using a keratometer. Non-cycloplegic refractive error was determined subjectively. Subjects with SC genotype were significantly taller than those with SS genotype. In the unadjusted data, height was correlated with VCD [p = 0.02, 0.44 mm deeper per 10 cm increase in height, 95% CI (0.65, 8.25)] and AL [p = 0.03, 0.42 mm longer for every 10 cm increase in height, 95%CI (0.49, 7.99)]. The relationship between height, VCD and AL was absent after adjustment for age, gender, genotype and weight. BMI (kg m(-2)) was correlated with AL/CR ratio in both unadjusted (p = 0.04, -0.10 decrease per 1 kg m(-2), 95% CI (-0.018, -0.001) and adjusted data (p = 0.05, -0.10 decrease per 10 kg m(-2), 95% CI (-0.0189, 0.0001). Refractive error was not related to height, weight or BMI. Physical size does not affect refractive error or optical components in adult patients with SCD.

SU-D-207-07: Implementation of Full/half Bowtie Filter Model in a Commercial Treatment Planning System for Kilovoltage X-Ray Imaging Dose Estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, S; Alaei, P

2015-06-15

Purpose: To implement full/half bowtie filter models in a commercial treatment planning system (TPS) to calculate kilovoltage (kV) x-ray imaging dose of Varian On-Board Imager (OBI) cone beam CT (CBCT) system. Methods: Full/half bowtie filters of Varian OBI were created as compensator models in Pinnacle TPS (version 9.6) using Matlab software (version 2011a). The profiles of both bowtie filters were acquired from the manufacturer, imported into the Matlab system and hard coded in binary file format. A Pinnacle script was written to import each bowtie filter data into a Pinnacle treatment plan as a compensator. A kV x-ray beam modelmore » without including the compensator model was commissioned per each bowtie filter setting based on percent depth dose and lateral profile data acquired from Monte Carlo simulations. To validate the bowtie filter models, a rectangular water phantom was generated in the planning system and an anterior/posterior beam with each bowtie filter was created. Using the Pinnacle script, each bowtie filter compensator was added to the treatment plan. Lateral profile at the depth of 3cm and percent depth dose were measured using an ion chamber and compared with the data extracted from the treatment plans. Results: The kV x-ray beams for both full and half bowtie filter have been modeled in a commercial TPS. The difference of lateral and depth dose profiles between dose calculations and ion chamber measurements were within 6%. Conclusion: Both full/half bowtie filter models provide reasonable results in kV x-ray dose calculations in the water phantom. This study demonstrates the possibility of using a model-based treatment planning system to calculate the kV imaging dose for both full and half bowtie filter modes. Further study is to be performed to evaluate the models in clinical situations.« less

Heparan sulfate deficiency leads to Peters anomaly in mice by disturbing neural crest TGF-β2 signaling

PubMed Central

Iwao, Keiichiro; Inatani, Masaru; Matsumoto, Yoshihiro; Ogata-Iwao, Minako; Takihara, Yuji; Irie, Fumitoshi; Yamaguchi, Yu; Okinami, Satoshi; Tanihara, Hidenobu

2009-01-01

During human embryogenesis, neural crest cells migrate to the anterior chamber of the eye and then differentiate into the inner layers of the cornea, the iridocorneal angle, and the anterior portion of the iris. When proper development does not occur, this causes iridocorneal angle dysgenesis and intraocular pressure (IOP) elevation, which ultimately results in developmental glaucoma. Here, we show that heparan sulfate (HS) deficiency in mouse neural crest cells causes anterior chamber dysgenesis, including corneal endothelium defects, corneal stroma hypoplasia, and iridocorneal angle dysgenesis. These dysfunctions are phenotypes of the human developmental glaucoma, Peters anomaly. In the neural crest cells of mice embryos, disruption of the gene encoding exostosin 1 (Ext1), which is an indispensable enzyme for HS synthesis, resulted in disturbed TGF-β2 signaling. This led to reduced phosphorylation of Smad2 and downregulated expression of forkhead box C1 (Foxc1) and paired-like homeodomain transcription factor 2 (Pitx2), transcription factors that have been identified as the causative genes for developmental glaucoma. Furthermore, impaired interactions between HS and TGF-β2 induced developmental glaucoma, which was manifested as an IOP elevation caused by iridocorneal angle dysgenesis. These findings suggest that HS is necessary for neural crest cells to form the anterior chamber via TGF-β2 signaling. Disturbances of HS synthesis might therefore contribute to the pathology of developmental glaucoma. PMID:19509472

Effect of laser peripheral iridotomy on anterior chamber angle anatomy in primary angle closure spectrum eyes

PubMed Central

Kansara, Seema; Blieden, Lauren S.; Chuang, Alice Z.; Baker, Laura A.; Bell, Nicholas P.; Mankiewicz, Kimberly A.; Feldman, Robert M.

2015-01-01

Purpose To evaluate the change in trabecular-iris circumference volume (TICV) after laser peripheral iridotomy (LPI) in primary angle closure (PAC) spectrum eyes Patients and Methods Forty-two chronic PAC spectrum eyes from 24 patients were enrolled. Eyes with anterior chamber abnormalities affecting angle measurement were excluded. Intraocular pressure, slit lamp exam, and gonioscopy were recorded at each visit. Anterior segment optical coherence tomography (ASOCT) with 3D mode angle analysis scans were taken with the CASIA SS-1000 (Tomey Corp., Nagoya, Japan) before and after LPI. Forty-two pre-LPI ASOCT scans and 34 post-LPI ASOCT scans were analyzed using the Anterior Chamber Analysis and Interpretation (ACAI, Houston, TX) software. A mixed-effect model analysis was used to compare the trabecular-iris space area (TISA) changes among 4 quadrants, as well as to identify potential factors affecting TICV. Results There was a significant increase in all average angle parameters after LPI (TISA500, TISA750, TICV500, and TICV750). The magnitude of change in TISA500 in the superior angle was significantly less than the other angles. The changes in TICV500 and TICV750 were not associated with any demographic or ocular characteristics. Conclusion TICV is a useful parameter to quantitatively measure the effectiveness of LPI in the treatment of eyes with PAC spectrum disease. PMID:26066504

A young Botswana patient with congenital iris ectropion uvea.

PubMed

Shifa, Jemal Zeberga; Nkomazana, Othokawa; Bekele, Negussie Alula; Kassa, Mamo Woldu

2016-01-01

Congenital iris ectropion is a rare condition; non-progressive anomaly characterised by the presence of iris pigment epithelium on the anterior surface of the iris stroma and is frequently associated with anterior iris insertion, dysgenesis of the drainage angle and glaucoma. This paper describes unusual case of bilateral case of congenital iris ectropion in adult patient with pupillary abnormality, normal anterior chamber angle structure and with no evidence of glaucoma.

Biometric gonioscopy and the effects of age, race, and sex on the anterior chamber angle

PubMed Central

Congdon, N G; Foster, P J; Wamsley, S; Gutmark, J; Nolan, W; Seah, S K; Johnson, G J; Broman, A T

2002-01-01

Aim: To utilise a novel method for making measurements in the anterior chamber in order to compare the anterior chamber angles of people of European, African, and east Asian descent aged 40 years and over. Methods: A cross sectional study on 15 people of each sex from each decade from the 40s to the 70s, from each of three racial groups—black, white, and Chinese Singaporeans. Biometric gonioscopy (BG) utilises a slit lamp mounted reticule to make measurements from the apparent iris insertion to Schwalbe's line through a Goldmann one mirror goniolens. The main outcome measures were BG measurements of the anterior chamber angle as detailed above. Results: There was no significant difference in angle measurement between black, white, and Chinese races in this study. However, at younger ages people of Chinese race appeared to have deeper angles than white or black people, whereas the angles of older Chinese were significantly narrower (p = 0.004 for the difference in slope of BG by age between Chinese and both black and white people). Conclusion: The failure to detect a difference in angle measurements between these groups was surprising, given the much higher prevalence of angle closure among Chinese. It appears that the overall apparent similarity of BG means between Chinese and Western populations may mask very different trends with age. The apparently more rapid decline in angle width measurements with age among Chinese may be due to the higher prevalence of cataract or “creeping angle closure.” However, longitudinal inferences from cross sectional data are problematic, and this may represent a cohort phenomenon caused by the increasing prevalence of myopia in the younger Singaporean population. PMID:11801496

Surgical management of anterior chamber epithelial cysts.

PubMed

Haller, Julia A; Stark, Walter J; Azab, Amr; Thomsen, Robert W; Gottsch, John D

2003-03-01

To review management strategies for treatment of anterior chamber epithelial cysts. Retrospective review of consecutive interventional case series. Charts of patients treated for epithelial ingrowth over a 10-year period by a single surgeon were reviewed. Cases of anterior chamber epithelial cysts were identified and recorded, including details of ocular history, preoperative and postoperative acuity, intraocular pressure (IOP), and ocular examination, type of surgical intervention, and details of further procedures performed. Seven eyes with epithelial cysts were identified. Patient age ranged from 1.5 to 53 years at presentation. Four patients were children. In four eyes, cysts were secondary to trauma, one case was presumably congenital, one case developed after corneal perforation in an eye with Terrien's marginal degeneration, and one case developed after penetrating keratoplasty (PK). Three eyes were treated with vitrectomy, en bloc resection of the cyst and associated tissue, fluid-air exchange and cryotherapy. The last four eyes were treated with a new conservative strategy of cyst aspiration (three cases) or local excision (one keratin "pearl" cyst), and endolaser photocoagulation of the collapsed cyst wall/base. All epithelial tissue was successfully eradicated by clinical criteria; one case required repeat excision (follow-up, 9 to 78 months, mean 45). Two eyes required later surgery for elevated IOP, two for cataract extraction and one for repeat PK. Final visual acuity ranged from 20/20 to hand motions, depending on associated ocular damage. Best-corrected visual results were obtained in the more conservatively managed eyes. Anterior chamber epithelial cysts can be managed conservatively in selected cases with good results. This strategy may be particularly useful in children's eyes, where preservation of the lens, iris, and other structures may facilitate amblyopia management. Copyright 2003 by Elsevier Science Inc.

Effects of Geometric Variations on Lift Augmentation of Simple-plenum-chamber Ground-effect Models

NASA Technical Reports Server (NTRS)

Davenport, Edwin E.

1961-01-01

Considerable interest has been shown during recent years in ground-effect vehicles. Of the various types proposed, the simple-plenum-chamber vehicle has indicated promise because, although the lift augmentation obtainable appears to be less than that of an annular jet, it may be somewhat less complicated structurally. The present investigation was undertaken to study the effects of some geometric variations upon lift augmentation of a simple plenum chamber within ground proximity. The variables included the ratio inlet area to exit area, plenum-chamber depth, and entrance configuration. An optimum plenum-chamber depth appeared to be between 3 and 10 percent of the plenum-chamber diameter with a ratio of inlet diameter to plenum-chamber diameter of 0.15 for the range of plenum-chamber depths investigated. The most important effect of multiple inlets was the elimination of negative lift augmentation, which was experienced with single sharp-edged inlets, at intermediate heights. Installation of a flared inlet and a turning-vane assembly improved lift augmentation of a single-inlet configuration at intermediate heights.

Involvement of the Anterior Segment of the Eye in Patients with Mucopolysaccharidoses: A Review of Reported Cases and Updates on the Latest Diagnostic Instrumentation.

PubMed

Bruscolini, A; Amorelli, G M; Rama, P; Lambiase, A; La Cava, M; Abbouda, A

2017-01-01

Mucopolysaccharidoses (MPS) are a heterogeneous group of rare inherited disorders, characterized by the lack or malfunction of lysosomal enzymes necessary for glycosaminoglycan (GAGs) catabolism, and their subsequent accumulation in many tissues and organs throughout the body. An overview of the current knowledge of corneal and anterior segment manifestations in patients with MPS was provided and clinical guidelines for their diagnosis and management were furnished. The anterior segment of the eye is usually involved in every subtype of MPS, with major complications including varying degrees of corneal opacification and raised intraocular pressure (IOP) with development of glaucoma. Their recognition and management can be very useful in the diagnosis of MPS. Novel techniques are available to objectively measure the grade and extent of corneal clouding and give information about the anatomy of the anterior chamber and the structures of the angle beyond the clouded cornea. It is advisable to take advantage of this new instrumentation in order to obtain thorough information on the ocular involvement and its related anterior chamber complications for a better management of patients with MPS, both in terms of visual prognosis and therapeutic outcome.

The change of magma chamber depth in and around the Baekdu Volcanic area from late Cenozoic

NASA Astrophysics Data System (ADS)

Lee, S. H.; Oh, C. W.; Lee, Y. S.; Lee, S. G.; Liu, J.

2016-12-01

The Baekdu Volcano is a 2750m high stratovolcanic cone resting on a basaltic shield and plateau and locates on the North Korea-China border. Its volcanic history can be divided into four stages (from the oldest to the youngest): (i) preshield plateau-forming eruptions, (ii) basalt shield formation, (iii) construction of a trachytic composite cone, and (iv) explosive ignimbrite forming eruptions. In the First stage, a fissure eruption produced basalts from the Oligocene to the Miocene (28-13 Ma) forming preshield plateau. Fissure and central eruptions occurred together during the shield-forming eruptions (4.21-1.70 Ma). In the third stage, the trachytic composite volcano formed during the Pleistocene (0.61-0.09 Ma). In this stage, magma changed to an acidic melt. The latest stage has been characterized by explosive ignimbrite-forming eruptions during the Holocene. The composite volcanic part consists of the Xiaobaishan, Lower, Middle and Upper Trachytes with rhyolites. The whole rock and clinopyroxene in basalts, trachytic and rhyolite, are analyzed to study the depth of magma chambers under the Baekdu Volcano. From the rhyolite, 9.8-12.7kbar is obtained for the depth of magma chamber. 3.7-4.1, 8.9-10.5 and 8.7 kbar are obtained from the middle, lower and Xiaobaishan trachytes. From the first and second stage basalts, 16.9-17.0 kbar and 14-14.4kbar are obtained respectively. The first stage basalt give extrusive age of 11.98 Ma whereas 1.12 and 1.09 Ma are obtained from the feldspar and groundmass in the second stage basalt. The Xiaobaishan trachyte and rhyolite give 0.25 and 0.21 Ma whereas the Middle trachyte gives 0.07-0.06 Ma. These data indicate that the magma chambers of the first and second stage basalts were located in the mantle and the magma chamber for the second stage basalt may have been underplated below continental crust. The Xiaobisan trachyte and rhyolite originated from the magma chamber in the depth of ca. 30-40 km and the Middle trachyte originated from the magma chamber in the depth of 9-13 km. These depths of magma chambers for trychyte and rhyolite are similar to the first, third and fourth magma chambers figured out from the seismic survey and the result of this study suggest that the depth of magma chambers under the Baekdu Volcano moved to shallow depth as time passed.

Anterior chamber depth studies.

PubMed

Hoffer, Kenneth J; Savini, Giacomo

2015-09-01

To compare the anterior chamber depth (ACD; corneal epithelium to lens) using 3 modalities and compare the change 1 day and 3 months postoperatively. Private practice, Santa Monica, California, USA. Nonrandomized prospective series. The mean optical pachymetry and immersion ultrasound (US) of the ACD and partial coherence interferometry (PCI) were measured. Optical pachymetry ACD was measured in 675 eyes postoperatively at 1 day and 3 months. The optical pachymetry ACD in 492 eyes was 3.17 mm ± 0.42 (SD); by immersion US, it was 2.99 ± 0.51 mm (0.18 mm deeper; P < .0001). In 178 eyes, the optical pachymetry ACD was 3.23 ± 0.45 mm; the PCI was 3.19 ± 0.48 mm (0.04 mm deeper), which was not statistically different (P > .05). In 675 eyes, optical pachymetry ACD preoperatively was 3.19 ± 0.40 mm. The postoperative 1-day optical pachymetry ACD was 4.35 ± 0.35 mm with a mean refractive error of -0.30 diopter (D); the final 3-month optical pachymetry ACD was 4.47 ± 0.31 mm, with a mean refractive error of -0.07 D (P < .0001). This is a mean intraocular lens (IOL) position shift of +0.12 mm posteriorly; the +0.23 D change represents a ratio of 1.92 D/mm of IOL axial movement. The PCI ACD was comparable with optical pachymetry, but careful immersion US led to a 0.18 mm shorter ACD reading that cannot be corrected by sound velocity. The posterior capsule contracted and moved the IOL posteriorly 0.12 mm, resulting in 0.23 D hyperopic shift. Dr. Hoffer owns the registered trademark name "Hoffer(®)" and receives royalties for its commercial use from Alcon Laboratories, Inc., Appasamy Associates, Carl Zeiss Meditec AG, DGH Technology, Inc., Ellex iScience, Inc., Haag-Streit AG, Nidek Co., Ltd., Tomey Corp., Topcon Medical Systems, Inc., and Ziemer USA, Inc., as well as royalties from Slack, Inc. for the textbook IOL Power. Neither author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

The Relationship between Anterior Chamber Depth, Axial Length and Intraocular Lens Power among Candidates for Cataract Surgery.

PubMed

Sedaghat, Mohammad Reza; Azimi, Ali; Arasteh, Peyman; Tehranian, Naghmeh; Bamdad, Shahram

2016-10-01

Basic anatomical parameters in ophthalmology are variable in different countries according to ethnic groups, genetics and some environmental factors. The aim of this study was to determine the relationship between axial length (AL), anterior chamber depth (ACD) and intraocular lens power (IOL) in a referral center from eastern Iran among patients who had cataract surgery, in comparison to studies from other regions of the world. In a cross-sectional retrospective study from 2011 to 2013, the records of 698 cataract patients referring to Khatam Al Anbia general hospital in Mashhad, Iran were evaluated. We divided patients, based on their AL and ACD, into three separate groups and compared their results. The SPSS software was used for data analysis. The Chi-Square test and the Independent-samples t-test were used to compare qualitative and quantitative data between two groups, respectively. The Kendall and the Pearson product-moment correlation tests were used to assess the relationship between AL and ACD. The linear Regression model was used to obtain a mathematical model to estimate ACD, using AL, age and sex. Among individuals who had normal AL (between 22-24.5mm), there was a positive correlation between AL and ACD (p<0.001, r=0.17), however, among individuals with short (AL<22mm) or long sightedness (AL>24.5mm), no significant correlation was detected. We also found that older people have shorter AL (p=0.001 and r=-0.287). Men have an average longer AL (23.7±2.4mm vs. 22.9±2.1mm; p<0.001) and deeper ACD compared to women (2.93±0.45mm vs. 2.82±0.42mm, p=0.002). Our findings were mostly similar to previous literature from other regions of the world and although some anatomical variations may exist regarding ophthalmic anatomy, factors like race and geographical area have little effect on the relationship between ACD, AL and IOL power calculation, furthermore our results support the use of third and fourth generation formulas for IOL power calculation.

Ethnic differences in lens parameters measured by ocular biometry in a cataract surgery population.

PubMed

Wang, Dajiang; Amoozgar, Behzad; Porco, Travis; Wang, Zhen; Lin, Shan C

2017-01-01

To investigate whether differences exist in lens position and other lens parameters among major ethnic groups with cataractous eyes, which may help explain racial differences in angle closure risk. This retrospective, cross-sectional study included 807 adult patients who had cataract surgery between years 2014 and 2016 at the University of California, San Francisco (UCSF). Adult patients of white, Asian, Hispanic and African-American ethnicity were included. Lens position (LP), defined as anterior chamber depth (ACD) + 1/2 lens thickness (LT), was assessed using measurements from optical biometry. Other assessed biometric parameters included axial length (AL), relative lens position (RLP) (defined as LP/AL), and anterior chamber depth (ACD). A total of 807 patients and 1361 eyes were included in this study from a database of patients having cataract surgery. Mean age was 69.2 years (age range from 18 to 101 years old), and 60.3% of patients were women. The mean LP measurements were 5.54±0.32 mm for white, 5.38±0.32 mm for Asian, 5.32±0.30 mm for Hispanic, and 5.40±0.28 mm for African-American participants. After adjusting for age, sex, and AL, significant differences were found when comparing LP in paired comparisons among White cohort with Asians (P<0.001), Hispanics (P<0.001) and African-Americans (P = 0.003). Additionally, when comparing RLP, similar significant results were found when comparing Whites with Asians (P<0.001), Hispanics (P<0.001) and African-Americans (P = 0.002). Lastly, pair-wise comparison of LT between ethnic groups showed significant differences while comparing Asians with Whites (P = 0.001) and Asians with African-Americans (P<0.001). The results of this study suggest that the LP of Hispanic, Asian, and African-American patients are significantly smaller than that of White patients, and among all ethnic groups, Hispanics and after Asians have the smallest LP (P<0.001) and RLP (P<0.001). These findings may have implications for the relative risk of angle closure and the potential IOP response after cataract surgery among different ethnic groups.

Demographics and ocular biometric characteristics of patients undergoing cataract surgery in Auckland, New Zealand.

PubMed

Yoon, Jinny J; Misra, Stuti L; McGhee, Charles Nj; Patel, Dipika V

2016-03-01

The aim is to investigate ethnic variation, in presentation and biometric parameters, within the population undergoing cataract surgery in Auckland. The design is a retrospective study. Four thousand nine hundred thirty-one eyes of 3524 consecutive patients undergoing cataract surgery in Auckland Public Hospital over 18 months were included in the study. Analysis of preoperative medical records was performed. Age, gender, self-reported ethnicity, keratometry, anterior chamber depth, axial length and intraocular lens (IOL) power data were collected. Māori (4.7%) were under-represented compared with the proportion of Māori attending the eye clinic (5.5%) and in the major patient catchment area (8.2%). People of Māori, Pacific and Indian ethnicities presented at a significantly younger age (66.4, 65.9 and 67.9 years, respectively) than those of Caucasian and Asian ethnicities (76.4 and 71.3 years, respectively, P < 0.001). Advanced cataract was more likely in Pacific peoples and Māori than Caucasians. The mean axial length was longest in Asian eyes (23.83 ± 1.52 mm). The mean anterior chamber depth in the eyes of Pacific peoples (3.20 ± 0.39 mm) was significantly greater than that of Caucasians (3.09 ± 0.42 mm, P = 0.001) and Asians (3.05 ± 0.49 mm, P < 0.001). The mean IOL power in Asian eyes was 19.45D. This was significantly lower than the IOL power required by Caucasian (20.72D, P < 0.001) and Pacific ethnicities (20.61D, P = 0.001). With-the-rule astigmatism was highly prevalent in Māori and Pacific peoples, whereas in all other ethnicities, against-the-rule astigmatism was more common. This study identified significant ethnic variation in presentation for cataract surgery and ocular biometric parameters. These data may help identify potential biometric refinements and those at risk of developing ocular morbidities known to be associated with these parameters. © 2015 Royal Australian and New Zealand College of Ophthalmologists.

SU-D-19A-01: Can Farmer-Type Ionization Chambers Be Used to Improve the Accuracy of Low-Energy Electron Beam Reference Dosimetry?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muir, B R; McEwen, M R

2014-06-01

Purpose: To investigate the use of cylindrical Farmer-type ionization chambers to improve the accuracy of low-energy electron beam calibration. Historically, these chamber types have not been used in beams with incident energies less than 10 MeV (R{sub 5} {sub 0} < 4.3 cm) because early investigations suggested large (up to 5 %) fluence perturbation factors in these beams, implying that a significant component of uncertainty would be introduced if used for calibration. More recently, the assumptions used to determine perturbation corrections for cylindrical chambers have been questioned. Methods: Measurements are made with cylindrical chambers in Elekta Precise 4, 8 andmore » 18 MeV electron beams. Several chamber types are investigated that employ graphite walls and aluminum electrodes with very similar specifications (NE2571, NE2505/3, FC65-G). Depth-ionization scans are measured in water in the 8 and 18 MeV beams. To reduce uncertainty from chamber positioning, measurements in the 4 MeV beam are made at the reference depth in Virtual Water™. The variability of perturbation factors is quantified by comparing normalized response of various chambers. Results: Normalized ion chamber response varies by less than 0.7 % for similar chambers at average electron energies corresponding to that at the reference depth from 4 or 6 MeV beams. Similarly, normalized measurements made with similar chambers at the reference depth in the 4 MeV beam vary by less than 0.4 %. Absorbed dose calibration coefficients derived from these results are stable within 0.1 % on average over a period of 6 years. Conclusion: These results indicate that the uncertainty associated with differences in fluence perturbations for cylindrical chambers with similar specifications is only 0.2 %. The excellent long-term stability of these chambers in both photon and electron beams suggests that these chambers might offer the best performance for all reference dosimetry applications.« less

[Opacification of an intraocular lens: calcification of hydrophilic intraocular lenses after gas tamponade of the anterior chamber].

PubMed

Schmidinger, G; Pemp, B; Werner, L

2013-11-01

A patient with endothelial dystrophy was treated with Descemet stripping automated endothelial keratoplasty (DSAEK) combined with cataract extraction and implantation of a hydrophilic intraocular lens (IOL, Lentis-L312, Oculentis) but visual acuity dropped from 0.15 logMAR to 0.52 logMAR 18 months later due to calcification of the IOL. With new methods of lamellar corneal transplantation being used more frequently the number of necessary anterior chamber tamponades with air/gas are increasing. In cataract cases in which a gas tamponade and transplantation might be necessary later on (cornea guttata), hydrophilic IOLs should be avoided.

[Quant therapy and the composition of the moister of the eye anterior chamber (an experimental study)].

PubMed

Pavliuk, E Iu; Sherkhoeva, D Ts; Pavliuk, A Iu; Khristoforov, V N

2005-01-01

We examined 12 rabbits, 6 of whom (12 eyes) were exposed to magneto-infrared laser radiation (MILR) and another 6 (12 eyes) were controls. The parameters of pulse and continuous infrared LED radiation were as follows: wavelength--860 nm, pulse capacity--2 W, mean radiation capacity--10 mW, magnetic field strength--up to 17 mTl. A study of the moister of the anterior chamber showed a MILR-induced activated metabolism, i.e. a better acid-base balance (ABB), more intense oxygenation in the ocular tissues and decreased acidosis. Higher concentrations of buffer bases (ABEe and SBEc) cause shifts in ABB towards metabolic alkalosis. A lower concentration of glucose denotes intensified processes related with its utilization. A lack of changes in the quantity of salts in the moister of the anterior chamber rules out the possibility of that the content of glucose would go down due to its dissolution with a big volume of newly produced moister. A lack of an increase in the concentration of whole protein, as observed after MILR, can be regarded as indirect evidence to absence of any adverse effect on the vascular wall.

A boussinesq model of natural convection in the human eye and the formation of Krukenberg's spindle.

PubMed

Heys, Jeffrey J; Barocas, Victor H

2002-03-01

The cornea of the human eye is cooled by the surrounding air and by evaporation of the tear film. The temperature difference between the cornea and the iris (at core body temperature) causes circulation of the aqueous humor in the anterior chamber of the eye. Others have suggested that the circulation pattern governs the shape of the Krukenberg spindle, a distinctive vertical band of pigment on the posterior cornea surface in some pathologies. We modeled aqueous humor flow the human eye, treating the humor as a Boussinesq fluid and setting the corneal temperature based on infrared surface temperature measurements. The model predicts convection currents in the anterior chamber with velocities comparable to those resulting from forced flow through the gap between the iris and lens. When paths of pigment particles are calculated based on the predicted flow field, the particles circulate throughout the anterior chamber but tend to be near the vertical centerline of the eye for a greatest period of time. Further, the particles are usually in close proximity to the cornea only when they are near the vertical centerline. We conclude that the convective flow pattern of aqueous humor is consistent with a vertical pigment spindle.

[Gonioscopy - How, Why, What for?

PubMed

Unterlauft, J D

2017-08-01

Aim Gonioscopy is used to exam the anterior chamber angle and the neighbouring structures. Gonioscopy can be performed using a contact lens, with the patient sitting at the slit lamp or in a supine position. Due to the total inner reflection of the cornea, the anterior chamber angle would otherwise be invisible in a healthy eye. During normal daily clinical routine, gonioscopy is often omitted, due to lack of time, although additional information could be gained. Materials and Methods The aim is to give a summary of the diagnostic possibilities using gonioscopy and to emphasise the importance of this relatively easy clinical method. Results The development of gonioscopy, the appropriate tools, proper procedure at the slit lamp and the most popular grading systems are described. In addition, an overview of detectable pathological changes in the anterior chamber angle is given and future prospects about developments in gonioscopy. Conclusion Gonioscopy can provide additional information otherwise missed by slit lamp examination or ophthalmoscopy alone. Up to now, no (semi-)automatic devices have been developed which could completely replace gonioscopy. Therefore gonioscopy remains an important part of a complete ophthalmological examination and should be learned, mastered and performed regularly by every ophthalmologist. Georg Thieme Verlag KG Stuttgart · New York.

A new slit lamp-based technique for anterior chamber angle estimation.

PubMed

Gispets, Joan; Cardona, Genís; Tomàs, Núria; Fusté, Cèlia; Binns, Alison; Fortes, Miguel A

2014-06-01

To design and test a new noninvasive method for anterior chamber angle (ACA) estimation based on the slit lamp that is accessible to all eye-care professionals. A new technique (slit lamp anterior chamber estimation [SLACE]) that aims to overcome some of the limitations of the van Herick procedure was designed. The technique, which only requires a slit lamp, was applied to estimate the ACA of 50 participants (100 eyes) using two different slit lamp models, and results were compared with gonioscopy as the clinical standard. The Spearman nonparametric correlation between ACA values as determined by gonioscopy and SLACE were 0.81 (p < 0.001) and 0.79 (p < 0.001) for each slit lamp. Sensitivity values of 100 and 87.5% and specificity values of 75 and 81.2%, depending on the slit lamp used, were obtained for the SLACE technique as compared with gonioscopy (Spaeth classification). The SLACE technique, when compared with gonioscopy, displayed good accuracy in the detection of narrow angles, and it may be useful for eye-care clinicians without access to expensive alternative equipment or those who cannot perform gonioscopy because of legal constraints regarding the use of diagnostic drugs.

Model of transient drug diffusion across cornea.

PubMed

Zhang, Wensheng; Prausnitz, Mark R; Edwards, Aurélie

2004-09-30

A mathematical model of solute transient diffusion across the cornea to the anterior chamber of the eye was developed for topical drug delivery. Solute bioavailability was predicted given solute molecular radius and octanol-to-water distribution coefficient (Phi), ocular membrane ultrastructural parameters, tear fluid hydrodynamics, as well as solute distribution volume (Vd) and clearance rate (Cla) in the anterior chamber. The results suggest that drug bioavailability is primarily determined by solute lipophilicity. In human eyes, bioavailability is predicted to range between 1% and 5% for lipophilic molecules (Phi>1), and to be less than 0.5% for hydrophilic molecules (Phi<0.01). The simulations indicate that the distribution coefficient that maximizes bioavailability is on the order of 10. It was also found that the maximum solute concentration in the anterior chamber (Cmax) and the time needed to reach Cmax significantly depend on Phi, Vd, and Cla. Consistent with experimental findings, model predictions suggest that drug bioavailability can be increased by lowering the conjunctival-to-corneal permeability ratio and reducing precorneal solute drainage. Because of its mechanistic basis, this model will be useful to predict drug transport kinetics and bioavailability for new compounds and in diseased eyes.

CASA-Mot technology: how results are affected by the frame rate and counting chamber.

PubMed

Bompart, Daznia; García-Molina, Almudena; Valverde, Anthony; Caldeira, Carina; Yániz, Jesús; Núñez de Murga, Manuel; Soler, Carles

2018-04-04

For over 30 years, CASA-Mot technology has been used for kinematic analysis of sperm motility in different mammalian species, but insufficient attention has been paid to the technical limitations of commercial computer-aided sperm analysis (CASA) systems. Counting chamber type and frame rate are two of the most important aspects to be taken into account. Counting chambers can be disposable or reusable, with different depths. In human semen analysis, reusable chambers with a depth of 10µm are the most frequently used, whereas for most farm animal species it is more common to use disposable chambers with a depth of 20µm . The frame rate was previously limited by the hardware, although changes in the number of images collected could lead to significant variations in some kinematic parameters, mainly in curvilinear velocity (VCL). A frame rate of 60 frames s-1 is widely considered to be the minimum necessary for satisfactory results. However, the frame rate is species specific and must be defined in each experimental condition. In conclusion, we show that the optimal combination of frame rate and counting chamber type and depth should be defined for each species and experimental condition in order to obtain reliable results.

Ocular Biometrics of Myopic Eyes With Narrow Angles.

PubMed

Chong, Gabriel T; Wen, Joanne C; Su, Daniel Hsien-Wen; Stinnett, Sandra; Asrani, Sanjay

2016-02-01

The purpose of this study was to compare the ocular biometrics between myopic patients with and without narrow angles. Patients with a stable myopic refraction (myopia worse than -1.00 D spherical equivalent) were prospectively recruited. Angle status was assessed using gonioscopy and biometric measurements were performed using an anterior segment optical coherence tomography and an IOLMaster. A total of 29 patients (58 eyes) were enrolled with 13 patients (26 eyes) classified as having narrow angles and 16 patients (32 eyes) classified as having open angles. Baseline demographics of age, sex, and ethnicity did not differ significantly between the 2 groups. The patients with narrow angles were on average older than those with open angles but the difference did not reach statistical significance (P=0.12). The central anterior chamber depth was significantly less in the eyes with narrow angles (P=0.05). However, the average lens thickness, although greater in the eyes with narrow angles, did not reach statistical significance (P=0.10). Refractive error, axial lengths, and iris thicknesses did not differ significantly between the 2 groups (P=0.32, 0.47, 0.15). Narrow angles can occur in myopic eyes. Routine gonioscopy is therefore recommended for all patients regardless of refractive error.

Liquid fuel vaporizer and combustion chamber having an adjustable thermal conductor

DOEpatents

Powell, Michael R; Whyatt, Greg A; Howe, Daniel T; Fountain, Matthew S

2014-03-04

The efficiency and effectiveness of apparatuses for vaporizing and combusting liquid fuel can be improved using thermal conductors. For example, an apparatus having a liquid fuel vaporizer and a combustion chamber can be characterized by a thermal conductor that conducts heat from the combustion chamber to the vaporizer. The thermal conductor can be a movable member positioned at an insertion depth within the combustion chamber that corresponds to a rate of heat conduction from the combustion chamber to the vaporizer. The rate of heat conduction can, therefore, be adjusted by positioning the movable member at a different insertion depth.

Preliminary study of a new intraocular method in the diagnosis and treatment of Propionibacterium acnes endophthalmitis following cataract extraction.

PubMed

Owens, S L; Lam, S; Tessler, H H; Deutsch, T A

1993-04-01

Late endophthalmitis, due to Propionibacterium acnes, developed in three patients following uncomplicated extracapsular cataract extraction and posterior chamber intraocular lens (PC-IOL) insertion. Cultures from the capsular bag yielded P. acnes in all three. With topical anesthesia and through an anterior chamber paracentesis, culture specimens were taken from and clindamycin irrigated into the capsular bag. Filtered 100% oxygen was introduced into the anterior chamber in two; the third also received an injection of gentamicin and dexamethasone into the capsular bag. After treatment, two patients received oral antibiotics; one received hyperbaric oxygen therapy. Visual acuity was improved and inflammation reduced in all three. However, after treatment, ocular toxic effects due to clindamycin were suspected in one. This approach offers several clear advantages, including topical anesthesia, outpatient management, elimination of the need for vitrectomy, and retention of the intraocular lens (IOL).

Late glaucoma after interstitial keratitis.

PubMed

Grant, W M

1975-01-01

In a systematic study of 45 patients who had syphilitic interstitial keratitis early in life and, many years later, were discovered to have glaucoma, there was evidence of two different but equally common mechanisms. In one group of patients, a deep-chamber type of glaucoma was superimposed on old inflammatory changes, was characteristically refractory to medical treatment, but did well with filtering surgery. The other group of patients had reversible angle-closure glaucoma associated with anatomically small anterior segments, and typically responded well to iridectomy. The late, refractory, deep-chamber type of glaucoma may involve endothelialization and formation of glass membrane in the angle, as seen in one excised eye. Occurrence of the shallow-chamber, reversible angle-closure type of glaucoma after interstitial keratitis may be coincidental, since no other evidence supports the idea that small anterior segments might be particularly prevalent among patients who have had congenital syphilis or interstitial keratitis.

Intracapsular lens extraction for the treatment of pupillary block glaucoma associated with anterior subluxation of the crystalline lens.

PubMed

Kim, Yong Joon; Ha, Seung Joo

2013-01-01

To report a case of pupillary block glaucoma associated with spontaneous crystalline lens subluxation into the anterior chamber in a 34-year-old man. Dry vitrectomy was performed for securing enough retrolental space, and an intracapsular lens extraction was then performed via a corneolimbal incision. Additional endothelial cell damage was avoided with an injection of viscoelastics and gentle extraction of the crystalline lens. After deepening of the anterior chamber, scleral fixation of the intraocular lens was performed with an ab externo technique. Two months after the operation, a well-fixated intraocular lens was observed and intraocular pressure was stable. The postoperative corneal astigmatism was -3.5 dpt, and the patient had a best-corrected visual acuity of 20/25. Postoperative complications included decreased endothelial cell count and sector iris paralysis near the incision site. An anteriorly subluxated crystalline lens can cause pupillary block glaucoma in healthy young adults. To prevent intraoperative complications, intracapsular lens extraction with dry vitrectomy can be a good surgical option. The endothelial cell density should be closely monitored after surgery.

Evaluation and comparison of indentation ultrasound biomicroscopy gonioscopy in relative pupillary block, peripheral anterior synechia, and plateau iris configuration.

PubMed

Matsunaga, Koichi; Ito, Kunio; Esaki, Koji; Sugimoto, Kota; Sano, Toru; Miura, Katsuya; Sasoh, Mikio; Uji, Yukitaka

2004-12-01

To evaluate and compare the findings and changes of the anterior chamber angle configuration with indentation ultrasound biomicroscopy (UBM) gonioscopy in relative pupillary block (RPB), peripheral anterior synechia (PAS), and plateau iris configuration (PIC). This study included 73 eyes of 52 patients with RPB (n = 26), PAS (n = 21), or PIC (n = 26). First, a conventional UBM scan was performed using a normal size standard eye cup before indentation. Then, for indentation UBM gonioscopy, scans were performed using a new eye cup that we designed. For evaluation of the angle, angle opening distance 500 and angle recess area were recorded and evaluated with regard to the effect of expansion on the anterior chamber angle. Indentation UBM gonioscopy showed the characteristic images in each of the eyes. The angle of all examined eyes was significantly widened with indentation (P < 0.01). The angle changes in eyes with RPB were significantly greater than in eyes with PAS or PIC (P < 0.01). Indentation UBM gonioscopy is a very useful method for observing the angle and diagnosis of RPB, PAS, and PIC.

Large (9 mm) Deep Anterior Lamellar Keratoplasty with Clearance of a 6-mm Optical Zone Optimizes Outcomes of Keratoconus Surgery.

PubMed

Busin, Massimo; Leon, Pia; Nahum, Yoav; Scorcia, Vincenzo

2017-07-01

To evaluate the outcomes of a 9-mm deep anterior lamellar keratoplasty (DALK) with removal of the deep stroma limited to the central 6-mm optical zone. Prospective, noncomparative, interventional case series. A total of 80 consecutive keratoconic eyes without deep stromal scarring, with at least 1 postoperative examination 1 month after complete suture removal. A standardized DALK was performed, including (1) deep trephination of the recipient bed 450 to 550 μm in depth and 9 mm in diameter; (2) pneumatic dissection; (3) debulking of approximately 80% of the anterior stroma; (4) removal of the deep stroma (bubble roof) from a central 6-mm optical zone; and (5) transplantation of a 9-mm anterior corneal lamella cut by microkeratome-assisted dissection (400-μm head) and sutured with a double running 10-0 nylon suture. Success rate and type of pneumatic dissection obtained; best spectacle-corrected visual acuity (BSCVA), refractive astigmatism (RA), and topographic astigmatism (TA), central corneal thickness (CCT) and endothelial cell density 12 months postoperatively; and intraoperative and postoperative complications. Pneumatic dissection created a "big bubble" in 67 of 80 eyes (83.7%), all of them but 1 (1.5%) being of type 1 according to the classification by Dua et al. After complete suture removal, BSCVA averaged 0.09±0.72 logarithm of the minimum angle of resolution (logMAR) and was ≥20/20 in 28 eyes (35%), ≥20/25 in 54 eyes (67.5%), and ≥20/40 in 76 eyes (95%); RA averaged 3.10±1.30 diopters (D), with 73 eyes (91%) within 4.5 D and none above 6 D; regular TA was detected in 72 eyes (90%); mean CCT was 492±62.10 μm; postoperative endothelial cell density averaged 2026±397cells/mm 2 with a mean cell loss of 11.2%. Intraoperative complications included loss of suction (n = 1) and perforation (n = 4). No conversion to penetrating keratoplasty was necessary. After surgery, double anterior chamber was observed in 2 cases (2.5%), both managed successfully by air filling of the anterior chamber. Stromal rejection was observed in 6 eyes (7.5%) and was reversed with topical steroids in all cases. In keratoconic eyes without deep stromal scars, the combination of a graft larger than conventional ones with limited removal of deep stroma can improve visual and refractive outcomes of DALK, while minimizing the rate of complications. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Refractive Outcomes After Femtosecond Laser-Assisted Cataract Surgery in Eyes With Anterior Chamber Phakic Intraocular Lenses.

PubMed

Steinwender, Gernot; Shajari, Mehdi; Kohnen, Thomas

2018-05-01

To report the efficacy, predictability, and safety of femtosecond laser-assisted cataract surgery (FLACS) in eyes with anterior chamber phakic intraocular lenses (IOLs). This retrospective case series included eyes with previous implantation of an angle-supported and an iris-fixated phakic IOL for the correction of myopia that underwent a combined procedure of phakic IOL ex-plantation and FLACS with in-the-bag implantation of a posterior chamber IOL. Postoperative corrected distance visual acuity (CDVA), predictability of refractive outcome, and occurrence of intraoperative and postoperative complications were analyzed. Ten eyes of 7 patients with significant cataract were included: 5 eyes with an angle-supported foldable hydrophobic phakic IOL, 4 eyes with an angle-supported polymethylmethacrylate (PMMA) phakic IOL, and 1 eye with an iris-fixated PMMA phakic IOL. Mean follow-up after FLACS was 8.4 ± 5.8 months. Mean interval between phakic IOL implantation and FLACS was 11.9 ± 4.0 years. After the combined procedure of phakic IOL explantation and FLACS, mean manifest refractive spherical equivalent (MRSE) was -0.11 ± 0.49 diopters (D) and MRSE was within ± 0.75 D of target refraction in all eyes. Four eyes received a toric posterior chamber IOL after phacoemulsification. Mean preoperative CDVA of 0.40 ± 0.23 logMAR improved significantly to 0.22 ± 0.11 logMAR postoperatively (P = .027). No intraoperative or postoperative complications occurred. The results in this series showed that FLACS in eyes with previous implantation of both rigid and foldable anterior chamber phakic IOLs offers good refractive outcomes with a high level of predictability and safety. [J Refract Surg. 2018;34(5):338-342.]. Copyright 2018, SLACK Incorporated.

[Eyeball structure changes in high myopic patients and their significance for forensic assessment].

PubMed

Liu, Yi-Chang; Xia, Wen-Tao; Zhou, Xing-Tao; Liu, Rui-Jue; Bian, Shi-Zhong; Ying, Chong-Liang; Zhu, Guang-You

2008-10-01

There are irreversible eyeball structural changes in high myopic patients. These changes include axial length, corneal radius, anterior chamber depth, fundus degeneration, macula thickness, etc. There is a close relationship between the damage degree of visual function and these changes. The incidence of complications, such as vitreous opacity, posterior vitreous detachment, cataract, glaucoma, posterior staphyloma and retina detachment, is also highly related to the myopia diopter. More and more researches have indicated that the myopia diopter and the level of visual function are affected by multiple factors. It is promising to detect all of these changes by different kinds of methods, and to assess visual function through these changes. By clarifying these changes, it is also useful to distinguish traumatic damage from disease to provide evidence for forensic assessment of eye injuries.

Experimental investigation of the effect of air cavity size in cylindrical ionization chambers on the measurements in 60Co radiotherapy beams

NASA Astrophysics Data System (ADS)

Swanpalmer, John; Johansson, Karl-Axel

2011-11-01

In the late 1970s, Johansson et al (1978 Int. Symp. National and International Standardization of Radiation Dosimetry (Atlanta 1977) vol 2 (Vienna: IAEA) pp 243-70) reported experimentally determined displacement correction factors (pdis) for cylindrical ionization chamber dosimetry in 60Co and high-energy photon beams. These pdis factors have been implemented and are currently in use in a number of dosimetry protocols. However, the accuracy of these factors has recently been questioned by Wang and Rogers (2009a Phys. Med. Biol. 54 1609-20), who performed Monte Carlo simulations of the experiments performed by Johansson et al. They reported that the inaccuracy of the pdis factors originated from the normalization procedure used by Johansson et al. In their experiments, Johansson et al normalized the measured depth-ionization curves at the depth of maximum ionization for each of the different ionization chambers. In this study, we experimentally investigated the effect of air cavity size of cylindrical ionization chambers in a PMMA phantom and 60Co γ-beam. Two different pairs of air-filled cylindrical ionization chambers were used. The chambers in each pair had identical construction and materials but different air cavity volume (diameter). A 20 MeV electron beam was utilized to determine the ratio of the mass of air in the cavity of the two chambers in each pair. This ratio of the mass of air in each pair was then used to compare the ratios of the ionizations obtained at different depths in the PMMA phantom and 60Co γ-beam using the two pairs of chambers. The diameter of the air cavity of cylindrical ionization chambers influences both the depth at which the maximum ionization is observed and the ionization per unit mass of air at this depth. The correction determined at depths of 50 mm and 100 mm is smaller than the correction currently used in many dosimetry protocols. The results presented here agree with the findings of Wang and Rogers' Monte Carlo simulations and show that the normalization procedure employed by Johansson et al is not correct.

A model for predicting sulcus-to-sulcus diameter in posterior chamber phakic intraocular lens candidates: correlation between ocular biometric parameters.

PubMed

Ghoreishi, Mohammad; Abdi-Shahshahani, Mehdi; Peyman, Alireza; Pourazizi, Mohsen

2018-02-21

The aim of this study was to determine the correlation between ocular biometric parameters and sulcus-to-sulcus (STS) diameter. This was a cross-sectional study of preoperative ocular biometry data of patients who were candidates for phakic intraocular lens (IOL) surgery. Subjects underwent ocular biometry analysis, including refraction error evaluation using an autorefractor and Orbscan topography for white-to-white (WTW) corneal diameter and measurement. Pentacam was used to perform WTW corneal diameter and measurements of minimum and maximum keratometry (K). Measurements of STS and angle-to-angle (ATA) were obtained using a 50-MHz B-mode ultrasound device. Anterior optical coherence tomography was performed for anterior chamber depth measurement. Pearson's correlation test and stepwise linear regression analysis were used to find a model to predict STS. Fifty-eight eyes of 58 patients were enrolled. Mean age ± standard deviation of sample was 28.95 ± 6.04 years. The Pearson's correlation coefficient between STS with WTW, ATA, mean K was 0.383, 0.492, and - 0.353, respectively, which was statistically significant (all P < 0.001). Using stepwise linear regression analysis, there is a statistically significant association between STS with WTW (P = 0.011) and mean K (P = 0.025). The standardized coefficient was 0.323 and - 0.284 for WTW and mean K, respectively. The stepwise linear regression analysis equation was: (STS = 9.549 + 0.518 WTW - 0.083 mean K). Based on our result, given the correlation of STS with WTW and mean K and potential of direct and essay measurement of WTW and mean K, it seems that current IOL sizing protocols could be estimating with WTW and mean K.

Study of the effective point of measurement for ion chambers in electron beams by Monte Carlo simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, L. L. W.; Rogers, D. W. O.

In current dosimetry protocols for electron beams, for plane-parallel chambers, the effective point of measurement is at the front face of the cavity, and, for cylindrical chambers, it is at a point shifted 0.5r upstream from the cavity center. In this study, Monte Carlo simulations are employed to study the issue of effective point of measurement for both plane-parallel chambers and cylindrical thimble chambers in electron beams. It is found that there are two ways of determining the position of the effective point of measurement: One is to match the calculated depth-ionization curve obtained from a modeled chamber to amore » calculated depth-dose curve; the other is to match the electron fluence spectrum in the chamber cavity to that in the phantom. For plane-parallel chambers, the effective point of measurement determined by the first method is generally not at the front face of the chamber cavity, which is obtained by the second method, but shifted downstream toward the cavity center by an amount that could be larger than one-half a millimeter. This should not be ignored when measuring depth-dose curves in electron beams. For cylindrical chambers, these two methods also give different positions of the effective point of measurement: The first gives a shift of 0.5r, which is in agreement with measurements for high-energy beams and is the same as the value currently used in major dosimetry protocols; the latter gives a shift of 0.8r, which is closer to the value predicted by a theoretical calculation assuming no-scatter conditions. The results also show that the shift of 0.8r is more appropriate if the cylindrical chamber is to be considered as a Spencer-Attix cavity. In electron beams, since the water/air stopping-power ratio changes with depth in a water phantom, the difference of the two shifts (0.3r) will lead to an incorrect evaluation of the water/air stopping-power ratio at the point of measurement, thus resulting in a systematic error in determining the absorbed dose by cylindrical chambers. It is suggested that a shift of 0.8r be used for electron beam calibrations with cylindrical chambers and a shift of 0.4r-0.5r be used for depth-dose measurements.« less

Study of the effective point of measurement for ion chambers in electron beams by Monte Carlo simulation.

PubMed

Wang, L L W; Rogers, D W O

2009-06-01

In current dosimetry protocols for electron beams, for plane-parallel chambers, the effective point of measurement is at the front face of the cavity, and, for cylindrical chambers, it is at a point shifted 0.5r upstream from the cavity center. In this study, Monte Carlo simulations are employed to study the issue of effective point of measurement for both plane-parallel chambers and cylindrical thimble chambers in electron beams. It is found that there are two ways of determining the position of the effective point of measurement: One is to match the calculated depth-ionization curve obtained from a modeled chamber to a calculated depth-dose curve; the other is to match the electron fluence spectrum in the chamber cavity to that in the phantom. For plane-parallel chambers, the effective point of measurement determined by the first method is generally not at the front face of the chamber cavity, which is obtained by the second method, but shifted downstream toward the cavity center by an amount that could be larger than one-half a millimeter. This should not be ignored when measuring depth-dose curves in electron beams. For cylindrical chambers, these two methods also give different positions of the effective point of measurement: The first gives a shift of 0.5r, which is in agreement with measurements for high-energy beams and is the same as the value currently used in major dosimetry protocols; the latter gives a shift of 0.8r, which is closer to the value predicted by a theoretical calculation assuming no-scatter conditions. The results also show that the shift of 0.8r is more appropriate if the cylindrical chamber is to be considered as a Spencer-Attix cavity. In electron beams, since the water/air stopping-power ratio changes with depth in a water phantom, the difference of the two shifts (0.3r) will lead to an incorrect evaluation of the water/air stopping-power ratio at the point of measurement, thus resulting in a systematic error in determining the absorbed dose by cylindrical chambers. It is suggested that a shift of 0.8r be used for electron beam calibrations with cylindrical chambers and a shift of 0.4r-0.5r be used for depth-dose measurements.

Depth of origin of magma in eruptions.

PubMed

Becerril, Laura; Galindo, Ines; Gudmundsson, Agust; Morales, Jose Maria

2013-09-26

Many volcanic hazard factors--such as the likelihood and duration of an eruption, the eruption style, and the probability of its triggering large landslides or caldera collapses--relate to the depth of the magma source. Yet, the magma source depths are commonly poorly known, even in frequently erupting volcanoes such as Hekla in Iceland and Etna in Italy. Here we show how the length-thickness ratios of feeder dykes can be used to estimate the depth to the source magma chamber. Using this method, accurately measured volcanic fissures/feeder-dykes in El Hierro (Canary Islands) indicate a source depth of 11-15 km, which coincides with the main cloud of earthquake foci surrounding the magma chamber associated with the 2011-2012 eruption of El Hierro. The method can be used on widely available GPS and InSAR data to calculate the depths to the source magma chambers of active volcanoes worldwide.

Depth of origin of magma in eruptions

PubMed Central

Becerril, Laura; Galindo, Ines; Gudmundsson, Agust; Morales, Jose Maria

2013-01-01

Many volcanic hazard factors - such as the likelihood and duration of an eruption, the eruption style, and the probability of its triggering large landslides or caldera collapses - relate to the depth of the magma source. Yet, the magma source depths are commonly poorly known, even in frequently erupting volcanoes such as Hekla in Iceland and Etna in Italy. Here we show how the length-thickness ratios of feeder dykes can be used to estimate the depth to the source magma chamber. Using this method, accurately measured volcanic fissures/feeder-dykes in El Hierro (Canary Islands) indicate a source depth of 11–15 km, which coincides with the main cloud of earthquake foci surrounding the magma chamber associated with the 2011–2012 eruption of El Hierro. The method can be used on widely available GPS and InSAR data to calculate the depths to the source magma chambers of active volcanoes worldwide. PMID:24067336

Correlating Corneal Biomechanics and Ocular Biometric Properties with Lamina Cribrosa Measurements in Healthy Subjects.

PubMed

Pérez Bartolomé, Francisco; Martínez de la Casa, Jose María; Camacho Bosca, Irene; Sáenz-Francés, Federico; Aguilar Munoa, Soledad; Martín Juan, Alberto; Garcia-Feijoo, Julian

2018-01-01

To examine interrelations between corneal biomechanics, ocular biometric variables and optic disc size (ODS), lamina cribosa depth (LCD) or thickness (LCT) in a healthy population. In a cross-sectional case-control study, the following measurements were made in 81 eyes of 81 participants: axial length, anterior chamber depth, lens thickness, and central corneal thickness using the optical biometer Lenstar LS900; and corneal hysteresis (CH), corneal resistance factor (CRF), Goldman-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) using the Ocular Response Analyzer. Serial horizontal enhanced depth imaging optical coherence tomography (EDI OCT) B-scans of the optic nerve head were obtained in each participant. Mean ODS, mean LCD, and mean LCT were measured in 11 equally spaced horizontal B-scans, excluding the LC insertion area under Bruch's membrane and scleral rim. LCD was measured in 74 of 81 eyes (91.36%); LCT in 60/81 (75.3%); ODS in 81/81 (100%). CRF was poorly, but significantly, correlated with LCT (Pearson's R = 0.264; P = 0.045). IOPcc, IOPg, CH, and ocular biometrics variables were poorly (non-significantly) correlated with LCD, LCT, and ODS. CRF was poorly but directly correlated with LCT. No association was detected between CH or ocular biometric variables and ODS, LCD, or LCT.

[Experimental hypertony caused by obstruction of the anterior chamber angle ab interno (author's transl)].

PubMed

Maguritsas, N; Vikas, C; Theodossiadis, G; Vergados, I; Velissaropoulos, P

1976-07-01

In 30 rabbits, separated into 3 groups (A, B and C), the entire area (A), three quarters (B) half of the anterior chamber angle (C) was experimentally obstructed by means of a homologous scleral graft. In groups A and B a statistically significant change of the intraocular pressure and of the cornea diameter was shown as compared with the control eye and group C. This change is due to the obstructed area of the angle. The increased intraocular pressure lasted for some months. The graft was well tolerated by the tissue of the angle and the obstruction of the angle was total, as was confirmed by means of the histological preparations.

Ophthalmic diagnostic tests, orbital anatomy, and adnexal histology of the broad-snouted caiman (Caiman latirostris).

PubMed

Oriá, Arianne P; Oliveira, Alberto Vinícius D; Pinna, Melissa H; Martins Filho, Emanoel F; Estrela-Lima, Alessandra; Peixoto, Tiago C; Silva, Renata Maria M da; Santana, Fernanda O; Meneses, Íris Daniela S; Requião, Kátia G; Ofri, Ron

2015-01-01

The aim of this study was to establish normal ophthalmic parameters for selected diagnostic tests, and to describe the orbital anatomy and adnexal histology of the broad-snouted caiman. A total of 35 Caiman latirostris that were free of obvious ocular diseases were used to measure the parameters in this investigation. Ages ranged from 5 to 15 years. Ophthalmic diagnostic tests were conducted, including evaluation of tear production with Schirmer Tear test-1 (STT1), culture of the conjunctival bacterial flora, applanation tonometry, conjunctival cytology, nictiating membrane incursion frequency test (NMIFT), endodontic absorbent paper point tear test (EAPPTT), palpebral fissure length measurement (PFL) and B-mode ultrasonography. Adnexal histology and skull samples were studied. Mean (±SD) STT1 was 3.4 ± 3.6 mm/min (95% confidence interval of 2.01-4.78 mm/min), intraocular pressure (IOP) was 12.9 ± 6.2 mmHg, NMIFT was 6.0 ± 3.5, EAPPTT was 17.1 ± 2.5 mm/min, PFL was 28.9 ± 3.0 mm, anterior chamber depth was 3.1 ± 0.3 mm, lens axial length was 8.4 ± 0.6 mm, vitreous chamber depth was 7.9 ± 0.7 mm and axial globe length was 19.9 ± 1.3 mm. For all animals evaluated, Bacillus sp., Diphteroids and Staphylococcus sp. were predominant. © 2013 American College of Veterinary Ophthalmologists.

Ethnic variations in myopia and ocular biometry among adults in a rural community in China: the Yunnan minority eye studies.

PubMed

Pan, Chen-Wei; Chen, Qin; Sheng, Xun; Li, Jun; Niu, Zhiqiang; Zhou, Hua; Wei, Tao; Yuan, Yuansheng; Zhong, Hua

2015-05-01

To determine the prevalence of myopia and ocular biometry in population-based samples of ethnic Yi and Han people living in an inland rural community in China. A random cluster sampling strategy was used to select ethnic Han and Yi adults aged 50 years or older living in Yunnan. Refractive error was determined by subjective refraction and ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD), and lens thickness (LT), which were measured using an Echoscan. Adults of Yi ethnicity had lower prevalence of myopia (10.3% vs. 8.1%; P = 0.02) and high myopia (2.3% vs. 1.6%; P = 0.10) than their counterparts of Han ethnicity. The prevalence of myopia increased with age (P for trend < 0.05), whereas the mean AL did not differ significantly among age groups in both ethnic groups (both P for trend > 0.05). In multivariate analysis, time spent outdoors was associated with myopia (P = 0.003) and AL (P < 0.001) but not high myopia (P = 0.33). No interaction effect was detected between ethnicity and other risk factors on myopia (all P > 0.05). Adjustment for lens nuclear opacity score reduced the excess prevalence of myopia in Han ethnicity by 37.5%. There was little evidence showing that ethnic disparities existed in the prevalence and risk factors between the major and minor ethnic groups living in the same communities in rural China. The "cohort effect" on myopia observed in many other populations was not seen in this study.

Central corneal thickness measurements and ultrasonographic study of the growing equine eye.

PubMed

Herbig, Lena E; Eule, J Corinna

2015-11-01

The aim of this study was to determine the central corneal thickness (CCT) of healthy equine eyes with high-frequency ultrasound (HF) and ultrasound biomicroscopy (UBM) and to measure the axial dimensions with B-mode ultrasound. Additionally, the influence of the age on the measured dimensions of the globe was analyzed. Fifty warm blood horses (mean age 23.0 ± 21.12 months) were divided into 3 age groups (group 1: 0-6 months; group 2: ≥7-30 months; and group 3: ≥31-78 months). Corneal measurements were performed with a 22-MHz and a 50-MHz transducer. Crystalline lens thickness (CLT), vitreous chamber depth (VCD), and axial globe length (AGL) were measured at a frequency of 10 MHz. Anterior chamber depth (ACD) was calculated. The eyes were measured under general anesthesia nonrelated to this study. The mean CCT of 50 eyes was 818 ± 41 μm. The mean values ± SD in mm for axial dimensions were AGL 34.7 ± 2.7, ACD 3.4 ± 0.7, CLT 10.0 ± 0.9, and VCD of 20.4 ± 1.5. A positive correlation with increasing age was found for all dimensions. No significant differences were found between the gender and the left or right eye. HF and UBM are valuable high-resolution imaging tools for CCT measurements in horses. The here-obtained values support previous findings that a positive correlation with increasing age exists for CCT, ACD, CLT, VCD, and AGL in horse. © 2015 American College of Veterinary Ophthalmologists.

Relation of anthropometric measurements to ocular biometric changes and refractive error in children with thalassemia.

PubMed

Elkitkat, Rania S; El-Shazly, Amany A; Ebeid, Weam M; Deghedy, Marwa R

2018-03-01

To evaluate and correlate anthropometric, biometric, and refractive error changes in thalassemia major (TM). One hundred children with TM and another hundred healthy controls were recruited. Height, weight, body mass index (BMI), and occipitofrontal circumference (OFC) were the anthropometric parameters recorded. Full ophthalmologic examination was performed, including best-corrected visual acuity, cycloplegic refraction, slit-lamp examination, Goldmann applanation tonometry, indirect ophthalmoscopy, keratometry (K readings), and ocular biometry. Compared to controls, children with TM were shorter and lighter, with a smaller BMI (p<0.001); however, no significant difference existed in OFC. Regarding ocular biometric data, patients with thalassemia had steeper mean K readings (p = 0.03), shorter axial length (AXL) (p = 0.005), shorter vitreous chamber depth (p<0.001), and thicker crystalline lens (p<0.001) than controls. Patients with thalassemia had a significant myopic shift (p = 0.003). Multiple regression analyses only showed a significant correlation between corneal astigmatism and both weight and height (β = -0.05 and p = 0.03 and β = 0.06 and p = 0.04, respectively). Spherical equivalent was significantly correlated to K readings, lens thickness, and anterior chamber depth (p<0.0001 for all parameters). Compared to controls, children with TM have significant retardation in general and ocular growth (smaller BMI and shorter AXL). Ocular growth changes probably resulted in compensatory biometric changes (steeper corneas and thicker lenses) to reach emmetropization, with an exaggerated response and subsequent myopic shift. However, growth retardation is not directly related to ocular growth changes, myopic shift, or variations in biometric parameters.

Femtosecond laser cutting of multiple thin corneal stromal lamellae for endothelial bioengineering.

PubMed

Bernard, Aurélien; He, Zhiguo; Forest, Fabien; Gauthier, Anne-Sophie; Peocʼh, Michel; Dumollard, Jean-Marc; Acquart, Sophie; Montard, Romain; Delbosc, Bernard; Gain, Philippe; Thuret, Gilles

2015-02-01

To assess the feasibility of cutting multiple thin stromal lamellae in human donor corneas using a commercial femtosecond laser (FSL) to provide cell carriers for future endothelial graft bioengineering. Eight edematous organ-cultured corneas not suitable for grafting for endothelial reasons were mounted on a Ziemer anterior chamber and cut with a Z6 FSL with 6 successive parallel cuts, from depth to surface. Target thickness of each lamella ranged from 100 to 150 μm depending on initial corneal thickness. Thickness was measured using anterior segment optical coherence tomography before and after cutting on mounted corneas, and on each stromal lamella after detachment. Scanning electron microscopy observation was performed on 4 lamellae and histological cross sections on 1 cornea before detachment. A median of 5 (minimum 3, maximum 7) lamellae was obtained per cornea. All lamellae still attached were the most posterior ones, suggesting that FSL was less efficient because of light scattering by edematous stroma. Cut precision and postdetachment swelling were correlated with anterior-posterior position within the cornea. Median lamella thickness was 127 μm (56-222 μm) before detachment and 196 μm (80-304 μm) after detachment. Surface state was consistent with previously reported FSL lamellar cuts during Descemet stripping automated endothelial keratoplasty. Up to 7 thin lamellae can be cut in stored corneas with an FSL. This method, once optimized primarily by using deswelled, more transparent corneas, could prove effective for recycling unsuitable donor corneas in corneal bioengineering processes.

The nest architecture of the Florida harvester ant, Pogonomyrmex badius.

PubMed

Tschinkel, Walter R

2004-01-01

The architecture of the subterranean nests of the Florida harvester ant, Pogonomyrmex badius, was studied through excavation and casting. Nests are composed of two basic units: descending shafts and horizontal chambers. Shafts form helices with diameters of 4 to 6 cm, and descend at an angle of about 15-20 degrees near the surface, increasing to about 70 degrees below about 50 cm in depth. Superficial chambers (< 15 cm deep) appear to be modified shafts with low angles of descent, and are distinct from deeper chambers. In larger nests, they have a looping, connected morphology. Chambers begin on the outside of the helix as horizontal-floored, circular indentations, becoming multi-lobed as they are enlarged. Chamber height is about 1 cm, and does not change with area. Chamber area is greatest in the upper reaches of the nest, and decreases with depth. Vertical spacing between chambers is least in the upper reaches and increases to a maximum at about 70 to 80% of the maximum depth of the nest. The distribution of chamber area is top-heavy, with about half the total area occurring in the top quarter of the nest. Each 10% depth increment of the nest contains 25 to 40% less area than the decile above it, no matter what the size of the nest. Nests grow by simultaneous deepening, addition of new chambers and/or shafts and enlargement of existing chambers. As a result, the vertical spacing between chambers is similar at all nest sizes, and the relative distribution of chamber area with relative nest depth did not change during colony growth (that is, the size-free nest shape was the same at all colony sizes). Total chamber area increased somewhat more slowly than the population of workers excavating the nest. The branching of shafts was consistently shallow (< 40 cm), somewhat more so in large nests than small. Large colonies rarely had more than 4 shaft/chamber series. Each new series contributed less to the total chamber area because its chambers were smaller. Incipient colonies were usually 40 to 50 cm deep while mature colonies were commonly 2.5 to 3.0 m deep. Workers captured near the top of a mature nest (and therefore older) and penned in escape proof enclosures, excavated larger nests than did young workers captured from the bottom of the nest. Most of this difference was due to a larger fraction of older workers engaging in digging, rather than an increase in their rate of work. All ages of workers produced similar top-heavy nests. When different ages of workers from different levels of a mature colony were allowed to re-assort themselves in a vertical test apparatus buried in the soil, older workers moved upward to assume positions in the upper parts of the nest, much as in the colonies from which they were taken. The vertical organization of workers based on age is therefore the product of active movement and choice. A possible template imparting information on depth is a carbon dioxide gradient. Carbon dioxide concentrations increased 5-fold between the surface and the depths of the nest. A preference of young workers for high carbon dioxide concentrations, and a tendency for workers to dig more under low carbon dioxide concentrations could explain both the vertical age-distribution of workers, and the top-heaviness of the nest's architecture.

Comparison of factors associated with occludable angle between american Caucasians and ethnic Chinese.

PubMed

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-11-21

To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40-80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese.

Comparison of Factors Associated With Occludable Angle Between American Caucasians and Ethnic Chinese

PubMed Central

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-01-01

Purpose. To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. Methods. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40–80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. Results. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Conclusions. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese. PMID:24168992

Iris concavity, corneal biomechanics, and their correlations with ocular biometry in a cohort of 10- to 12-year-old UK school boys: baseline data.

PubMed

Shah, Ameet; Low, Sancy; Garway-Heath, David F; Foster, Paul J; Barton, Keith

2014-04-17

Pigment dispersion syndrome is associated with iris concavity. This study investigated the prevalence of iris concavity, defined as a measurement of ≤-0.1 mm, in a cohort of 10- to 12-year-old boys, and explored the relationship between iris curvature and anterior segment biometry. Associations with corneal biomechanical parameters also were explored. A cohort of school boys (n = 96) was recruited from a local school. Anterior segment optical coherence tomography (AS-OCT) was performed under accommodative and nonaccommodative conditions, and iris curvature quantified. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured with the ocular response analyzer (ORA). Noncontact axial biometry was performed using laser interferometry. The prevalence of iris concavity was 24% on distance fixation, increasing to 65% on accommodation. Variables significantly associated with nonaccommodating iris curvature were lens vault (P = 0.02) and mean keratometry (P = 0.02). For both variables acting jointly, R(2) = 0.30. Variables associated significantly with accommodating iris curvature were anterior chamber depth (P = 0.009), lens vault (P = 0.049), and mean scleral spur angle (P < 0.0001). For these three variables acting jointly, R(2) = 0.33. Significant association was found between CH and spur-to-spur distance (R(2) = 0.07, P = 0.025). Iris concavity was a common finding in this cohort and related to anterior segment biometric parameters. Further work is required to clarify whether anatomical differences exist between iris concavity seen in the adolescent eye and that found in adults with pigment dispersion syndrome. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Reliability and repeatability of swept-source Fourier-domain optical coherence tomography and Scheimpflug imaging in keratoconus.

PubMed

Szalai, Eszter; Berta, András; Hassan, Ziad; Módis, László

2012-03-01

To evaluate the repeatability and reliability of a recently introduced swept-source Fourier-domain anterior segment optical coherence tomography (AS-OCT) system and a high-resolution Scheimpflug camera and to assess the agreement between the 2 instruments when measuring healthy eyes and eyes with keratoconus. Department of Ophthalmology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary. Evaluation of diagnostic test or technology. Three consecutive series of anterior segment images were taken with AS-OCT (Casia SS-1000) followed by rotating Scheimpflug imaging (Pentacam high resolution). Axial keratometry in the steep and flat meridians and astigmatism values were recorded. Pachymetry in the apex, center, and the thinnest position and anterior chamber depth (ACD) measurements were also taken. This study enrolled 57 healthy volunteers (57 eyes) and 56 patients (84 eyes) with keratoconus. Significant difference was found in all measured anterior segment parameters between normal eyes and keratoconic eyes (P<.05). In keratoconic eyes, the difference between repeated measurements was less with AS-OCT than with Scheimpflug imaging in every keratometry and astigmatism value, in apical thickness, and in ACD. For keratometry, the thinnest and central pachymetry measurement repeatability was better in healthy eyes than in keratoconic eyes with both instruments. In general, the mean difference between AS-OCT and Scheimpflug imaging was higher in cases of keratoconus. Significant differences in keratometry, pachymetry, and ACD results were found between AS-OCT and Scheimpflug imaging. However, the repeatability of the measurements was comparable. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Traumatic anterior dislocation of the crystalline lens and its surgical management.

PubMed

Srećković, Sunčica; Janićijević Petrović, Mirjana; Jovanović, Svetlana; Paunović, Svetlana; Sarenac, Tatjana

2012-02-01

This paper reports a case of a 57-year old female who had sustained a blunt ocular trauma resulting in anterior dislocation of the crystalline lens and acute painful visual loss in the left eye. The patient was managed with anterior chamber intracapsular phacoemulsification through a small anterior capsulotomy, pars plana vitrectomy, and surgical iridotomy. Aphakia was corrected by a contact lens. Two months after the surgery, the best corrected visual acuity was 0.9 in the left eye. The vision and retina remained stable in her follow-up examination 1 year later. Anterior dislocation of the crystalline lens can cause severe complications so that dislocated lens should be removed immediately.

Ultrasonographic biometry of the normal eye of the Persian cat.

PubMed

Mirshahi, A; Shafigh, S H; Azizzadeh, M

2014-07-01

To describe the normal ultrasonographic biometry of the Persian cat's eyes using B-mode ultrasonography. In a cross-sectional study, 20 healthy Persian cats with no history of previous ophthalmic disease were examined. Ocular biometry of the left and right eyes was measured using B-mode ultrasonography. Comparison of the average measurements between left and right eyes and between vertical and horizontal planes was performed using paired-sample t test. Correlation of ocular parameters with sex, age, head circumference and eye colour was evaluated. Mean ± standard deviation (SD) measurements of the ocular structures of anterior chamber, lens thickness, vitreous chamber and anterior to posterior dimension of the globe in 40 eyes were 4.1 ± 0.7, 7.7 ± 0.5, 8.2 ± 0.4 and 20.7 ± 1.0 mm, respectively. No significant difference was found between the ocular biometry of the left and right eyes or the horizontal and vertical planes. Of the ocular parameters, the following had a significant positive correlation with head circumference: axial globe length, anterior chamber and lens thickness. The vitreous body had a positive correlation with age. Regarding the breed predisposition of Persian cats to ocular problems, the present study provides baseline information for further clinical investigations of ocular abnormalities using B-mode ultrasonography. © 2014 Australian Veterinary Association.

SU-F-T-72: Experimental Determination of the Positionuncertainties for ROOS Ionization Chambers in Clinical Electron Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voigts-Rhetz, P von; Zink, K; University Hospital Giessen-Marburg, Marburg

2016-06-15

Purpose: National and international dosimetry protocols assume a position accuracy for ionization chambers of less than 0.2mm. To follow this precept the manufacturer PTW-Freiburg introduced a positioning assistance system (TRUFIX) for their particular ion chambers. Aim of this study is an experimental investigation of the positioning uncertainties for ROOS-type ionization chambers. Methods: For all measurements a linear accelerator Elekta Synergie was used. The experiments were performed in a water-phantom. To collimate the electron beam a 10×10cm{sup 2} applicator was installed. All measured depth dose curves were normalized to their maximum. In all cases the TRUFIX system was applied for chambermore » positioning. For the first measurement series, to determine the positioning reproducibility of a ROOS chamber, one person placed the chamber three times in a 6 MeV electron beam. The mean value of this three measurements was the reference for further six random persons who repeated this procedure. The results were compared for different depths (R{sub 50}, z{sub ref} and R{sub p}). To investigate the impact of different individual chambers of the same type 10 different ROOS chambers were placed by the same person in a 6, 12 and 18MeV electron beam and the measured reference depths z{sub ref} were compared. Results: The absolute positioning reproducibility is less than 0.1mm for the same person. The positioning uncertainties are increasing up to +/−0.3mm if different persons perform the chamber’s positioning within the water phantom. The comparison of the 10 different ROOS chambers resulted in reference depths z{sub ref} with deviations in the range of +/−0.45mm for all energies. Conclusion: The position accuracy of 0.2mm can be fulfilled with the TRUFIX system. The comparison of the 10 different ROOS ionization chambers showed noticeable deviations in the determined reference depth. The impact of a positioning uncertainty of about 0.3–0.4mm on the total perturbation correction will be considered.« less

Free radical development in phacoemulsification cataract surgery.

PubMed

Takahashi, Hiroshi

2005-02-01

Phacoemulsification and aspiration (PEA) has become the most popular cataract surgery, due to the establishment of safe surgical techniques and development of associated instruments. However, corneal endothelial damage still represents a serious complication, as excessive damage can lead to irreversible bullous keratopathy. In addition to causes such as mechanical or heat injuries, free radical formation due to ultrasound has been posited as another cause of corneal endothelium damage in PEA. Ultrasound in aqueous solution induces cavitation, directly causing water molecule disintegration and resulting in the formation of hydroxylradicals, the most potent of the reactive oxygen species. Considering the oxidative insult to endothelial cells caused by free radicals, their presence in the anterior chamber may represent one of the most harmful factors during these procedures. Indeed, some researchers have recently started to evaluate PEA from the perspective of oxidative stress. Conversely, the major ingredient in ophthalmic viscosurgical devices (OVDs), which are indispensable for maintaining the anterior chamber in PEA surgery, is sodium hyaluronate, a known free radical scavenger. OVDs can thus be expected to provide some anti-free radical effect during PEA procedures. In addition, since commercially available OVDs display different properties regarding retention in the anterior chamber during PEA, the anti-free radical effect of OVDs is likely to depend on behavior during irrigation and aspiration. The present study followed standard PEA procedures in an eye model and measured hydroxylradicals in the anterior chamber using electron spin resonance. The kinetics of free radical intensity and effects of several OVDs during clinical PEA were also demonstrated. These studies may be of significance in re-evaluating OVDs as a chemical protectant for corneal endothelium, since the OVD has thus far only been regarded as a physical barrier. In addition, many reports about corneal endothelium damage during PEA have been published, but objective evaluation of various damaging factors has been difficult. The present assay of free radicals in a simulation of clinical PEA offers the first method to quantitatively assess stress on the corneal endothelium.

Assessing the True Intraocular Pressure in the Non-human Primate.

PubMed

McAllister, Faith; Harwerth, Ronald; Patel, Nimesh

2018-02-01

For glaucoma patients, high intraocular pressure (IOP) is a risk factor for progressive neuropathy. Similarly, animal models used to study the disease are based on an experimental elevation of IOP. Thus, accurate IOP measurements are important in characterizing experimental models and resulting effects. The purpose of the present study was to investigate IOP measurements in a non-human primate model of experimental glaucoma by comparing clinical tonometry (Tono-Pen and TonoVet) to the true IOP from intracameral manometry. A total of 17 rhesus macaque eyes from 12 animals were used for this study. Eleven eyes had no previous experimental intervention, whereas six eyes were at varying stages of laser-induced experimental glaucoma. IOPs were adjusted by inserting a needle in the anterior chamber that was attached to a pressure transducer and syringe pump system. The anterior chamber IOP was adjusted to values between 10 and 50 mmHg and corresponding measures with Tono-Pen and TonoVet were taken. The IOPs by TonoVet and Tono-Pen were linearly related over the range of pressures tested (slope = 0.68 normal/healthy and 0.72 experimental glaucoma). For the most, TonoVet measures overestimated IOP at all anterior chamber pressure settings (mean difference of 3.17 mmHg, 95% CI 12.53 to -4.74 normal and 3.90 mmHg, 95% CI 12.90 to -6.53 experimental glaucoma). In contrast, Tono-Pen measures overestimated IOP at lower IOPs and underestimated at higher IOP (slope = -0.26 normal and -0.21 experimental glaucoma). The TonoVet and Tono-Pen tonometers that are often used to assess IOP in both clinical and experimental settings generally reflect the status of IOP, but the results from this study suggest that the instruments need calibration with true anterior chamber pressure for accurate measures in experimental models of glaucoma.

Interface quality of different corneal lamellar–cut depths for femtosecond laser–assisted lamellar anterior keratoplasty

PubMed Central

Zhang, Chenxing; Bald, Matthew; Tang, Maolong; Li, Yan; Huang, David

2015-01-01

PURPOSE To evaluate interface quality of different corneal lamellar–cut depths with the femtosecond laser and determine a feasible range of depth for femtosecond laser–assisted lamellar anterior keratoplasty. SETTING Casey Eye Institute, Portland, Oregon, USA. DESIGN Experimental study. METHODS Full lamellar cuts were made on 20 deepithelialized human cadaver corneas using the femtosecond laser. The cut depth was 17% to 21% (100 μm), 31%, 35%, 38% to 40%, and 45% to 48% of the central stromal thickness. Scanning electron microscopy images of cap and bed surfaces were subjectively graded for ridge and roughness using a scale of 1 to 5 (1 = best). The graft–host match was evaluated by photography and optical coherence tomography in a simulated procedure. RESULTS The ridge score was correlated with the cut depth (P = .0078, R = 0.58) and better correlated with the percentage cut depth (P = .00024, R = 0.73). The shallowest cuts had the least ridges (score 1.25). The 31% cut depth produced significantly less ridges (score 2.15) than deeper cuts. The roughness score ranged from 2.19 to 3.08 for various depths. A simulated procedure using a 100 μm host cut and a 177 μm (31%) graft had a smooth interface and flush anterior junction using an inverted side-cut design. CONCLUSIONS The femtosecond laser produced more ridges in deeper lamellar cuts. A depth setting of 31% stromal thickness might produce adequate surface quality for femtosecond laser–assisted lamellar anterior keratoplasty. The inverted side-cut design produced good edge apposition even when the graft was thicker than the host lamellar–cut depth. PMID:25747165

Effect of chamber characteristics, loading and analysis time on motility and kinetic variables analysed with the CASA-mot system in goat sperm.

PubMed

Del Gallego, R; Sadeghi, S; Blasco, E; Soler, C; Yániz, J L; Silvestre, M A

2017-02-01

Several factors unrelated to the semen samples could be influencing in the sperm motility analysis. The aim of the present research was to study the effect of four chambers with different characteristics, namely; slide-coverslip, Spermtrack, ISAS D4C10, and ISAS D4C20 on the sperm motility. The filling procedure (drop or capillarity) and analysis time (0, 120 and 240s), depth of chamber (10 or 20μm) and field on motility variables were analysed by use of the CASA-mot system in goat sperm. Use of the drop-filling chambers resulted in greater values than capillarity-filling chambers for all sperm motility and kinetic variables, except for LIN (64.5% compared with 56.3% of motility for drop- and capillarity-filling chambers respectively, P<0.05). There were no significant differences in total sperm motility between different chamber depths, however, use of the 20μm-chambers resulted in greater sperm progressive motility rate, VSL and LIN, and less VCL and VAP than chambers with a lesser depth. There was less sperm motility and lesser values for kinetic variables as time that elapsed increased between sample loading and sperm evaluation. For sperm motility, use of droplet-loaded chambers resulted in similar values of MOT in all microscopic fields, but sperm motility assessed in capillarity-loaded chambers was less in the central fields than in the outermost microscopic fields. For goats, it is recommended that sperm motility be analysed using the CASA-mot system with a drop-loaded chamber within 2min after filling the chamber. Copyright © 2016 Elsevier B.V. All rights reserved.

A case report of progressive obstruction of Ex-PRESS miniature glaucoma shunt after transient flat anterior chamber and treatment using Nd:YAG laser.

PubMed

Tanito, Masaki; Sano, Ichiya; Ohira, Akihiro

2015-01-08

We report a case of Ex-PRESS miniature glaucoma shunt obstruction resulting from progressive iris synechial formation after transient anterior chamber shallowing. A 68-year-old woman with pseudoexfoliation glaucoma in her right eye underwent filtration surgery with implantation of the Ex-PPESS shunt (model P-50, Alcon Japan, Tokyo, Japan) in combination with intra-surgical 0.04% mitomycin C use. After the anterior chamber injection of viscoelastic material and 100% sulfur hexafluoride gas for treatment of early postoperative over filtration, the intraocular pressure (IOP) was controlled between 9 and 12 mmHg. On postoperative day 121, gonioscopy showed that synechial formation around the shunt obstructed the axial port leaving the relief port opened. On postoperative day 274, the intraocular pressure increased to 40 mmHg and synechiae obstructed both the axial and relief ports. Dispersion of iris tissue by neodymium:yttrium-aluminium-garnet (Nd:YAG) laser (2 mJ, one shot to each port) opened both ports and immediately lowered the IOP, leaving peripheral anterior synechiae around the shunt. Up to postoperative day 400, the IOP was controlled between 13 and 15 mmHg, and the cystic bleb was maintained. The synechiae formed gradually extends around the shunt's shaft and can result in later external obstruction of the relief port. The current case requires further follow-up since synechiae remaining around the shaft can cause future obstruction. We emphasize the fact that, if the iris synechiae to the shunt once formed, it can progress and obstruct the shunt ports later.

Anterior Segment Ischemia after Strabismus Surgery

PubMed Central

Göçmen, Emine Seyhan; Atalay, Yonca; Evren Kemer, Özlem; Sarıkatipoğlu, Hikmet Yavuz

2017-01-01

A 46-year-old male patient was referred to our clinic with complaints of diplopia and esotropia in his right eye that developed after a car accident. The patient had right esotropia in primary position and abduction of the right eye was totally limited. Primary deviation was over 40 prism diopters at near and distance. The patient was diagnosed with sixth nerve palsy and 18 months after trauma, he underwent right medial rectus muscle recession. Ten months after the first operation, full-thickness tendon transposition of the superior and inferior rectus muscles (with Foster suture) was performed. On the first postoperative day, slit-lamp examination revealed corneal edema, 3+ cells in the anterior chamber and an irregular pupil. According to these findings, the diagnosis was anterior segment ischemia. Treatment with 0.1/5 mL topical dexamethasone drops (16 times/day), cyclopentolate hydrochloride drops (3 times/day) and 20 mg oral fluocortolone (3 times/day) was initiated. After 1 week of treatment, corneal edema regressed and the anterior chamber was clean. Topical and systemic steroid treatment was gradually discontinued. At postoperative 1 month, the patient was orthophoric and there were no pathologic symptoms besides the irregular pupil. Anterior segment ischemia is one of the most serious complications of strabismus surgery. Despite the fact that in most cases the only remaining sequel is an irregular pupil, serious circulation deficits could lead to phthisis bulbi. Clinical properties of anterior segment ischemia should be well recognized and in especially risky cases, preventative measures should be taken. PMID:28182149

Experimental determination of the effective point of measurement of cylindrical ionization chambers for high-energy photon and electron beams.

PubMed

Huang, Yanxiao; Willomitzer, Christian; Zakaria, Golam Abu; Hartmann, Guenther H

2010-01-01

Measurements of depth-dose curves in water phantom using a cylindrical ionization chamber require that its effective point of measurement is located at the measuring depth. Recommendations for the position of the effective point of measurement with respect to the central axis valid for high-energy electron and photon beams are given in dosimetry protocols. According to these protocols, the use of a constant shift P(eff) is currently recommended. However, this is still based on a very limited set of experimental results. It is therefore expected that an improved knowledge of the exact position of the effective point of measurement will further improve the accuracy of dosimetry. Recent publications have revealed that the position of the effective point of measurement is indeed varying with beam energy, field size and also with chamber geometry. The aim of this study is to investigate whether the shift of P(eff) can be taken to be constant and independent from the beam energy. An experimental determination of the effective point of measurement is presented based on a comparison between cylindrical chambers and a plane-parallel chamber using conventional dosimetry equipment. For electron beams, the determination is based on the comparison of halfvalue depth R(50) between the cylindrical chamber of interest and a well guarded plane-parallel Roos chamber. For photon beams, the depth of dose maximum, d(max), the depth of 80% dose, d(80), and the dose parameter PDD(10) were used. It was again found that the effective point of measurement for both, electron and photon beams Dosimetry, depends on the beam energy. The deviation from a constant value remains very small for photons, whereas significant deviations were found for electrons. It is therefore concluded that use of a single upstream shift value from the centre of the cylindrical chamber as recommended in current dosimetry protocols is adequate for photons, however inadequate for accurate electron beam dosimetry.

The effect of bevacizumab for anterior segment neovascularization after silicone oil removal in eyes with previous vitreoretinal surgery.

PubMed

Batman, C; Ozdamar, Y

2010-07-01

To report the outcomes of the use of intracameral bevacizumab for iris neovascularization occurring after silicone oil (SO) removal in eyes undergoing vitreoretinal surgery (VRS). This study included 12 eyes that had iris neovascularization after SO removal. The clinical outcomes of 12 eyes after intravitreal bevacizumab injection were reviewed. There were eight men and four women with an average age of 41.58+/-12.68 years. All eyes had VRS for various vitreoretinal diseases. After the mean follow-up period of 9.7+/-5.3 months, SO removal was performed. Then, the patients were followed for more than 2 months and detailed retinal examinations and intraocular pressure (IOP) were normal during this period, but rubeosis iridis (RI) developed. RI was treated with 1 dose of 1.25 mg bevacizumab into the anterior chamber. After a mean follow-up period of 4.8+/-2.2 months, the regression of iris neovacularization was detected and IOP was below 21 mmHg in all eyes. Anterior segment neovascularization (ASNV) may develop through various mechanisms in patients with VRS after SO removal, and anterior chamber injection of bevacizumab may lead to regression of ASNV.

SU-F-T-321: The Effect of an Electromagnetic Array Used for Patient Localization and Tumor Tracking On OSLD in Vivo Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rea, A; Kuruvilla, A; Gill, G

Purpose: The purpose of this study was to observe the effect of an electromagnetic array used for patient localization and tumor tracking on optically-stimulated luminescent in-vivo dosimetry. Methods: A linear accelerator equipped with four photon energies was used to irradiate optically stimulated luminescent dosimeters (OSLDs) at the respective dmax depths and in the buildup region, with and without the presence of an electromagnetic array used for tumor tracking and patient localization. The OSLDs were placed on solid water slabs under 5 mm bolus and on each face of an octagonal phantom, and irradiated using both static beam and arc geometry,more » with and without the electromagnetic array under our setup. The electromagnetic array was placed 6 cm above the phantom to coincide with similar distances used during patient treatment. Ionization chamber measurements in a water phantom were also taken initially for comparison with the simple geometry OSLD measurements and published data. Results: Under simple geometry, a negligible change was observed at dmax for all energies when the electromagnetic array was placed over the setup. When measuring at five millimeter depth, increases of 1.3/3.1/16/18% were observed for energies 4X/6X/10X/15X respectively when the electromagnetic array was in place. Measurements using the octagonal phantom yielded scattered results for the lateral and posterior oblique fields, and showed increases in dose to the OSLDs placed on the anterior and lateral anterior faces of the phantom. Conclusion: Placing the electromagnetic array very close to the patient’s surface acts as a beam spoiler in the buildup region (at 5 mm depth), which in turn causes an increase in the measured dose reading of the OSLD. This increase in dose is more pronounced when the OSLD is placed directly underneath the electromagnetic array than off to one side or the other.« less

Neodymium:YAG laser cutting of intraocular lens haptics.

PubMed

Gorn, R A; Steinert, R F

1985-11-01

Neodymium:YAG laser cutting of polymethylmethacrylate and polypropylene anterior chamber and posterior chamber intraocular lens haptics was studied in terms of ease of transection and physical structure of the cut areas as seen by scanning electron microscopy. A marked difference was discovered, with the polymethylmethacrylate cutting easily along transverse planes, whereas the polypropylene resisted cutting along longitudinal fibers. Clinical guidelines are presented.

Progress in anterior chamber angle imaging for glaucoma risk prediction - A review on clinical equipment, practice and research.

PubMed

V K, Shinoj; Hong, Xun Jie Jeesmond; V M, Murukeshan; M, Baskaran; Tin, Aung

2016-12-01

The visualization capabilities of various ocular imaging instruments can generally be categorized into photographic (e.g. gonioscopy, Pentacam, RetCam) and optical tomographic (e.g. optical coherence tomography (OCT), photoacoustic (PA) imaging, ultrasound biomicriscopy (UBM)) methods. These imaging instruments allow vision researchers and clinicians to visualize the iridocorneal angle, and are essential in the diagnosis and management of glaucoma. Each of these imaging modalities has particular benefits and associated drawbacks in obtaining repeatable and reliable measurement in the evaluation of the angle. This review article in this context summarized recent progresses in anterior chamber imaging techniques in glaucoma diagnosis and follow-up procedures. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Vitrectomy-assisted phacoemulsification for lenticular coloboma.

PubMed

Agarwal, Ashvin; Narang, Priya; Agarwal, Amar

2017-02-01

We describe a technique to prevent continuous vitreous hydration during phacoemulsification in eyes with lenticular coloboma. The hydration results from communication between the anterior and posterior chambers from the edges of the colobomatous defect. To avoid this, a valved trocar is placed at the pars plana site around the area of the lenticular defect, which allows a limited dry vitrectomy during phacoemulsification. Intermittent vitrectomy with a moderate cutting rate and low vacuum parameters accompanied by temporary halting of the phacoemulsification procedure prevents vitreous herniation into the anterior chamber and limits the extension of zonular compromise, facilitating safe phacoemulsification with appropriate capsule expansion and fixation devices and implantation of an intraocular lens. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

The toxic effect of different concentrations of povidone iodine on the rabbit's cornea.

PubMed

Jiang, Jin; Wu, Miaoqin; Shen, Ting

2009-01-01

To investigate the effects of polyvinylpyrrolidone (i.e., povidone) iodine (PVP-I) in different concentrations on the rabbit's cornea. PVP-I in various concentrations was instilled into the conjunctival sac and injected into the anterior chamber independently. The toxicity to the cornea was assessed by fluorescence dye, specular microscopy, and corneal pachymetry. After conjunctival sac PVP-I instillation, severe epithelial damage was observed at the concentrations of 5.0% and 2.5%. After anterior chamber PVP-I injection, significant corneal edema was observed at the concentrations of 2.0% and 1.5%. It can be safe and feasible to use 0.5% or 1.0% concentrations of PVP-I in conjunctival sac instillation for preoperative antisepsis.

Ultrasound biomicroscopic findings in hallerman-streiff syndrome.

PubMed

Sato, Miho; Terasaki, Hiroko; Amano, Emil; Okamoto, Yoko; Miyake, Yozo

2002-01-01

To demonstrate the usefulness of ultrasound biomicroscopy in detecting the morphological changes in the lens caused by the spontaneous absorption of lens material and to detect fundus abnormalities in a patient with Hallermann-Streiff syndrome. Case report of an infant diagnosed at the age of 2 months as having Hallermann-Streiff syndrome. Spontaneous lens absorption occurred during the course of follow-up and was detected only by ultrasound biomicroscopy after the patient was prepared for cataract surgery. The changes in the anterior chamber depth and lens shapes were documented by ultrasound biomicroscopy. Retinal folds that were barely observable by conventional ophthalmoscopy because of a dense cataract were clearly shown by ultrasound biomicroscopy. Ultrasound biomicroscopy can be used to examine the lenses of eyes that are not observable with conventional optical instruments. Ultrasound biomicroscopy can also be used to study the posterior segment of microphthalmic eyes. We recommend preoperative ultrasound biomicroscopy to prevent unnecessary anesthesia and surgical preparation.

The importance of hyporheic sediment respiration in several mid-order Michigan rivers: Comparison between methods in estimates of lotic metabolism

USGS Publications Warehouse

Uzarski, D.G.; Stricker, C.A.; Burton, T.M.; King, D. K.; Steinman, A.D.

2004-01-01

Metabolism was measured in four Michigan streams, comparing estimates made using a flow-through chamber designed to include the hyporheic zone to a 20 cm depth and a traditional closed chamber that enclosed to a 5 cm depth. Mean levels of gross primary productivity and community respiration were consistently greater in the flow-through chamber than the closed chamber in all streams. Ratios of productivity to respiration (P/R) were consistently greater in the closed chambers than the flow-through chambers. P/R ratios were consistently <1 in all streams when estimated with flow-through chambers, suggesting heterotrophic conditions. Maintenance of stream ecosystem structure and function therefore is dependent on subsidies either from the adjacent terrestrial system or upstream sources. Our results suggest that stream metabolism studies that rely on extrapolation of closed chambers to the whole reach will most likely underestimate gross primary productivity and community respiration.

The nest architecture of the ant Odontomachus brunneus.

PubMed

Cerquera, Lina M; Tschinkel, Walter R

2010-01-01

The architecture of the subterranean nests of the ant Odontomachus brunneus (Patton) (Hymenoptera: Formicidae) was studied by means of casts with dental plaster or molten metal. The entombed ants were later recovered by dissolution of plaster casts in hot running water. O. brunneus excavates simple nests, each consisting of a single, vertical shaft connecting more or less horizontal, simple chambers. Nests contained between 11 and 177 workers, from 2 to 17 chambers, and 28 to 340 cm(2) of chamber floor space and reached a maximum depth of 18 to 184 cm. All components of nest size increased simultaneously during nest enlargement, number of chambers, mean chamber size, and nest depth, making the nest shape (proportions) relatively size-independent. Regardless of nest size, all nests had approximately 2 cm(2) of chamber floor space per worker. Chambers were closer together near the top and the bottom of the nest than in the middle, and total chamber area was greater near the bottom. Colonies occasionally incorporated cavities made by other animals into their nests.

Characterizing a Rat Brca2 Knockout Model

DTIC Science & Technology

2007-05-01

synechiae (adhesion of iris to lens), and anterior segment dysgenesis (adhesion of lens to cornea). The cataractous lens cells extend circumferentially...around the lens capsule to the posterior (arrowheads). ac, anterior chamber; c, cornea; i, iris ; l, lens; lc, lens capsule; r, retina; m, mineralization...to DSB forma - tion, chromosomal damage, and cell death resulting from ionizing radiation (reviewed by Pellegrini and Venkitaraman, 2004). Evidence from

Comparison of efficacy and ocular surface toxicity of topical preservative-free methylprednisolone and preserved prednisolone in the treatment of acute anterior uveitis.

PubMed

Hedayatfar, Alireza; Hashemi, Hassan; Asgari, Soheila; Chee, Soon-Phaik

2014-04-01

The aim of this study was to compare the antiinflammatory effect and ocular surface toxicity of topical nonpreserved methylprednisolone sodium succinate 1% and preserved prednisolone acetate suspension 1% for the management of acute anterior uveitis (AAU). In this prospective, randomized, investigator-masked, comparative clinical trial, patients with mild-to-moderate noninfectious AAU were assigned randomly to receive either hourly nonpreserved methylprednisolone 1% (group A) or preserved prednisolone 1% (group B) eye drops followed by a 2-week tapering regimen. Anterior chamber cells and flare were clinically evaluated for the objective comparison of the antiinflammatory effect. The main outcome measure was the percentage of patients with a resolution of inflammation (anterior chamber cells <1+) on day 14. Ocular surface toxicity was assessed by means of the corneal fluorescein staining score, tear breakup time, Schirmer I test, and questionnaire-based grading of ocular discomfort parameters. Seventy-two eyes of 68 patients were studied, of which 38 eyes were enrolled in group A and 34 eyes were enrolled in group B. On day 14, 76.3% of the patients in group A had resolution of inflammation compared with 70.6% of the patients in group B, proving noninferiority (χ = 0.303, P = 0.582). The mean anterior chamber cell grade reduction for patients in group A was similar to that in group B (2.52 vs. 2.86, respectively; P = 0.92). Group A patients showed significantly lower corneal fluorescein staining scores (P < 0.001) and reported milder subjective ocular discomfort (0.55 vs. 1.43, P = 0.01) as compared with group B. Both preparations demonstrated equal antiinflammatory effects for the treatment of AAU. Nonpreserved methylprednisolone eye drops exhibited a significantly lower ocular surface toxicity profile and milder subjective discomfort when compared with that exhibited by preserved prednisolone.

Caldera subsidence and magma chamber depth of the Olympus Mons volcano, Mars

NASA Technical Reports Server (NTRS)

Zuber, M. T.; Mouginis-Mark, P. J.

1992-01-01

An axisymmetric finite element model is constructed to calculate elastic stresses in a volcanic edifice to examine the relationship between surface tectonism, caldera subsidence, and the physical characteristics of Olympus Mons' magmatic reservoir. Model results indicate that the surface stress state is not strongly sensitive to the aspect ratio or pressure distribution of the magma chamber, or to the contrast in stiffness between the magma chamber and surroundings, but is strongly dependent on the depth and width of the chamber. A gross similarity is suggested between the configurations of the magmatic plumbing systems of Olympus Mons and several well-studied terrestrial volcanoes such as the Hawaiian shields.

Truly simultaneous SS-OCT of the anterior and posterior human eye with full anterior chamber and 50° retinal field of views (Conference Presentation)

NASA Astrophysics Data System (ADS)

McNabb, Ryan P.; Viehland, Christian; Keller, Brenton; Vann, Robin R.; Izatt, Joseph A.; Kuo, Anthony N.

2017-02-01

Optical coherence tomography (OCT) has revolutionized clinical observation of the eye and is an indispensable part of the modern ophthalmic practice. Unlike many other ophthalmic imaging techniques, OCT provides three-dimensional information about the imaged eye. However, conventional clinical OCT systems image only the anterior or the posterior eye during a single acquisition. Newer OCT systems have begun to image both during the same acquisition but with compromises such as limited field of view in the posterior eye or requiring rapid switching between the anterior and posterior eye during the scan. We describe here the development and demonstration of an OCT system with truly simultaneous imaging of both the anterior and posterior eye capable of imaging the full anterior chamber width and 50° on the retina (macula, optic nerve, and arcades). The whole eye OCT system was developed using custom optics and optomechanics. Polarization was utilized to separate the imaging channels. We utilized a 200kHz swept-source laser (Axsun Technologies) centered at 1040±50nm of bandwidth. The clock signal generated by the laser was interpolated 4x to generate 5504 samples per laser sweep. With the whole eye OCT system, we simultaneously acquired anterior and posterior segments with repeated B-scans as well as three-dimensional volumes from seven healthy volunteers (other than refractive error). On three of these volunteers, whole eye OCT and partial coherence interferometry (LenStar PCI, Haag-Streit) were used to measure axial eye length. We measured a mean repeatability of ±47µm with whole eye OCT and a mean difference from PCI of -68µm.

Egress route of emulsified 20 centistokes silicone oil from anterior chamber of rabbit.

PubMed

Ohira, A; Chihara, E; Soji, T

1994-07-01

Silicone oil is used in recent clinical practice, however, it may cause adverse reactions in the eyes. When the high viscosity silicone oil is contaminated with low molecular weight silicone oil, the contamination may cause ocular toxicity or elevation of the intraocular pressure. To obtain information on the distribution of this preparation, emulsified 20 centistokes silicone oil was injected into the anterior chamber of rabbit eyes. The silicone oil droplets were visualized by light and electron microscopy by using oil soluble phthalocyanine blue. This copper containing dye remains in the tissue after removal of the silicone oil by organic solvents. Two and 4 weeks after an injection, the silicone emulsion was observed as numerous small vacuoles with blue precipitate at the margin of vacuoles within elongated trabecular endothelial cells, fibroblasts along the route of uveoscleral outflow and cells of the iris. Three hours after the injection, only a few vacuoles were present in these cells. These results demonstrated that the emulsified silicone oil leaves the anterior chamber through the conventional and unconventional routes. Phagocytosis by the trabecular endothelial cells and fibroblasts along the uveoscleral route caused an accumulation of the emulsified silicone oil in these cells. With chronic exposure to emulsified silicone oil, changes in the trabecular meshwork may lead to a reduction in the outflow of aqueous humor and cause glaucoma.

[Diode laser in "Malignant Glaucoma" treatment].

PubMed

Bresson Dumont, H; Ballereau, L; Lehoux, A; Santiago, P-Y

2006-05-01

Malignant glaucoma remains one of the most dramatic complications of ocular surgery. It can occur after glaucoma surgery but also after iridotomy, capsulotomy, or cataract extraction. However, the mechanisms remain unclear. to evaluate diode laser cyclodestruction as a complementary treatment in refractory malignant glaucoma. Seven women with malignant glaucoma with onset several months before (mean, 43 months; range, 12-96 months), in whom shallow anterior chamber and high IOP (25 mmHg +/- 5.5 treated with 2.86 +/- 0.9 topical and systemic medications) persisted despite prior surgical treatment (mean, 2; range, 1-5). Controlateral eyes had hyperopia (mean, +3.7 D, range, +1 to +6), five had shallow anterior chamber and high IOP. UBM detected plateau iris in four women. Seven eyes with malignant glaucoma and three controlateral eyes underwent cyclodestruction with diode laser (Viridis Twin Quantel Medical, laser, 810 nm), 22 burns around 270 degrees , 2 mm from the limbus for glaucomatous eyes and 15 inferior burns for controlateral eyes. Resolution of malignant glaucoma, with lower pressure (mean, 35%; range, 10%-70%), lower levels of medications (64%), final IOP at 13.2 mmHg (+/- 4.7), and deepening anterior chamber was achieved in all cases (mean follow-up, 18 months; range, 12-22). Cycloplegic topical treatment was stopped in 70% of cases. Diode laser cyclodestruction can help to resolve refractory malignant glaucoma. Larger UBM studies could help us to better understand the mechanisms of malignant glaucoma.

Comparative evaluation of aqueous humor viscosity.

PubMed

Davis, Kyshia; Carter, Renee; Tully, Thomas; Negulescu, Ioan; Storey, Eric

2015-01-01

To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Twenty-six raptors, ten dogs, three cats, and one horse. Animals were euthanized for reasons unrelated to this study. Immediately, after horizontal and vertical corneal dimensions were measured, and anterior chamber paracentesis was performed to quantify anterior chamber volume and obtain aqueous humor samples for viscosity analysis. Dynamic aqueous humor viscosity was measured using a dynamic shear rheometer (AR 1000 TA Instruments, New Castle, DE, USA) at 20 °C. Statistical analysis included descriptive statistics, unpaired t-tests, and Tukey's test to evaluate the mean ± standard deviation for corneal diameter, anterior chamber volume, and aqueous humor viscosity amongst groups and calculation of Spearman's coefficient for correlation analyses. The mean aqueous humor viscosity in the barred owl was 14.1 centipoise (cP) ± 9, cat 4.4 cP ± 0.2, and dog 2.9 cP ± 1.3. The aqueous humor viscosity for the horse was 1 cP. Of the animals evaluated in this study, the raptor aqueous humor was the most viscous. The aqueous humor of the barred owl is significantly more viscous than the dog (P < 0.0001). The aqueous humor viscosity of the raptor, dog, cat, and horse can be successfully determined using a dynamic shear rheometer. © 2014 American College of Veterinary Ophthalmologists.

ANTERIOR CHAMBER FLARE DURING BEVACIZUMAB TREATMENT IN EYES WITH EXUDATIVE AGE-RELATED MACULAR DEGENERATION.

PubMed

Hautamäki, Asta; Luoma, Arto; Immonen, Ilkka

2016-11-01

To study the anterior chamber flare during bevacizumab treatment of exudative age-related macular degeneration. During a 2-year prospective follow-up, 50 patients recently diagnosed with exudative age-related macular degeneration were treated at once-a-month visits if subretinal or intraretinal fluid or a new hemorrhage was present in the lesion area. Flare was measured weekly during the first month and then monthly in both eyes. Higher flare was associated with older age (P = 0.007, Linear Mixed Model), higher number of smoking pack-years (P = 0.019), macular cysts (P = 0.041), and pseudophakia (P = 0.003). The levels gradually increased during the follow-up (P < 0.0001) but less in the eyes with classic CNV (P = 0.011). Flare decreased during treatment-free periods lasting for at least two consecutive visits (P = 0.005). A peak in flare was observed 1 week after the first injection (P = 0.034, Wilcoxon signed rank test). In the fellow eyes, higher flare values in the beginning of the follow-up were associated with later conversion into exudative age-related macular degeneration (P = 0.015, Mann-Whitney U test). Anterior chamber flare correlated poorly with the CNV activity. Higher levels may, however, precede or exist early in the process that leads to the development of exudative age-related macular degeneration.

Anterior but not posterior choroid changed before and during Valsalva manoeuvre in healthy Chinese: a UBM and SS-OCT study

PubMed Central

Li, Fei; Gao, Kai; Li, Xingyi; Chen, Shida; Huang, Wenbin; Zhang, Xiulan

2017-01-01

Purpose To determine if the anterior choroid is involved in ocular change during the Valsalva manoeuvre (VM). Materials and methods Fifty-three healthy volunteers aged 18–65 years with normal visual field test results and no history of intraocular pressure (IOP) exceeding 21 mm Hg were recruited. Anterior and posterior choroidal changes before and during VM were recorded by ultrasound microscope and swept-source optical coherence tomography, respectively. Parameters of the anterior segment included ciliary body thickness (CBT0), thickness of the choroid at a distance of 4 mm from the root of the iris (CT4), anterior placement of the ciliary body (APCB) and trabecular–ciliary angle (TCA). Thickness of different layers of retina and posterior choroid were also measured and compared before and during VM. IOP, blood pressure (BP), heart rate (HR), axial length, spherical equivalent refractive error and pupil diameter (PD) were also recorded and analysed. Results VM caused elevated IOP, systolic BP, diastolic BP and increased HR. There was a significant increase in anterior parameters including CBT0, CT4 and APCB (p<0.001), but not in TCA or PD (p>0.05). The mean change of CBT0, CT4 and APCB were: from 1.00±0.09 mm to 1.11±0.10 mm (p<0.001), from 0.29±0.04 mm to 0.36±0.05 mm (p<0.001), from 0.76±0.11 mm to 0.88±0.13 mm (p<0.001), respectively. However, there is no significant change in posterior choroid (from 215.74±60.23 µm to 214.82±61.32 µm, p=0.17). Conclusion We found that VM did not affect the posterior choroid, but it did cause thickening of the anterior choroid and the ciliary body, both of which led to a larger anterior placement of the ciliary body and a narrowed anterior chamber. The anterior (but not the posterior) choroid could be related to IOP elevation and a narrowed anterior chamber in primary angle closure diseases. PMID:28432110

Eye Growth in Term- And Preterm-Born Eyes Modeled From Magnetic Resonance Images

PubMed Central

Munro, Robert J.; Fulton, Anne B.; Chui, Toco Y. P.; Moskowitz, Anne; Ramamirtham, Ramkumar; Hansen, Ronald M.; Prabhu, Sanjay P.; Akula, James D.

2015-01-01

Purpose. We generated a model of eye growth and tested it against an eye known to develop abnormally, one with a history of retinopathy of prematurity (ROP). Methods. We reviewed extant magnetic resonance images (MRIs) from term and preterm-born patients for suitable images (n = 129). We binned subjects for analysis based upon postmenstrual age at birth (in weeks) and ROP history (“Term” ≥ 37, “Premature” ≤ 32 with no ROP, “ROP” ≤ 32 with ROP). We measured the axial positions and curvatures of the cornea, anterior and posterior lens, and inner retinal surface. We fit anterior chamber depth (ACD), posterior segment depth (PSD), axial length (AL), and corneal and lenticular curvatures with logistic growth curves that we then evaluated for significant differences. We also measured the length of rays from the centroid to the surface of the eye at 5° intervals, and described the length versus age relationship of each ray, Lray(x), using the same logistic growth curve. We determined the rate of ray elongation, Eray(x), from Lray dy/dx. Then, we estimated the scleral growth that accounted for Eray(x), G(x), at every age and position. Results. Relative to Term, development of ACD, PSD, AL, and corneal and lenticular curvatures was delayed in ROP eyes, but not Premature eyes. In Term infants, G(x) was fast and predominantly equatorial; in age-matched ROP eyes, maximal G(x) was offset by approximately 90°. Conclusions. We produced a model of normal eye growth in term-born subjects. Relative to normal, the ROP eye is characterized by delayed, abnormal growth. PMID:26024095

Relationship between iris surface features and angle width in Asian eyes.

PubMed

Sidhartha, Elizabeth; Nongpiur, Monisha Esther; Cheung, Carol Y; He, Mingguang; Wong, Tien Yin; Aung, Tin; Cheng, Ching-Yu

2014-10-23

To examine the associations between iris surface features with anterior chamber angle width in Asian eyes. In this prospective cross-sectional study, we recruited 600 subjects from a large population-based study, the Singapore Epidemiology of Eye Diseases (SEED) study. We obtained standardized digital slit-lamp iris photographs and graded the iris crypts (by number and size), furrows (by number and circumferential extent), and color (higher grade denoting darker iris). Vertical and horizontal cross-sections of anterior chamber were imaged using anterior segment optical coherence tomography. Angle opening distance (AOD), angle recess area (ARA), and trabecular-iris space area (TISA) were measured using customized software. Associations of the angle width with the iris surface features in the subject's right eyes were assessed using linear regression analysis. A total of 464 eyes of the 464 subjects (mean age: 57.5 ± 8.6 years) had complete and gradable data for crypts and color, and 423 eyes had gradable data for furrows. After adjustment for age, sex, ethnicity, pupil size, and corneal arcus, higher crypt grade was independently associated with wider AOD750 (β [change in angle width per grade higher] = 0.018, P = 0.023), ARA750 (β = 0.022, P = 0.049), and TISA750 (β = 0.011, P = 0.019), and darker iris was associated narrower ARA750 (β = -0.025, P = 0.044) and TISA750 (β = -0.013, P = 0.011). Iris surface features, assessed and measured from slit-lamp photographs, correlated well with anterior chamber angle width; irises with more crypts and lighter color were associated with wider angle. These findings may provide another imaging modality to assess angle closure risk based on iris surface features. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Anterior segment biometry with 2 imaging technologies: very-high-frequency ultrasound scanning versus optical coherence tomography.

PubMed

Piñero, David P; Plaza, Ana Belén; Alió, Jorge L

2008-01-01

To determine the interchangeability of 2 anterior segment imaging systems: a very-high-frequency (VHF) ultrasound scanning system (Artemis 2, Ultralink LLC) and an optical coherence tomography (OCT) system (Visante, Zeiss). Vissum Instituto Oftalmologico de Alicante, Alicante, Spain. This study comprised 20 eyes without pathology or previous surgery. The anterior chamber depth (ACD), central corneal thickness (CCT), angle-to-angle distance (ATA), and the iridocorneal angle size (IAS) at the 0-degree and 180-degree positions were measured with 2 imaging techniques: VHF ultrasound scanning and OCT. Analysis of agreement and interchangeability was performed by the Bland and Altman method. In addition, each measurement was performed 3 times consecutively to determine intrasession repeatability by means of the coefficient of variation (CV) and the intraclass correlation coefficient (ICC). No statistically significant differences were found between imaging techniques in ACD, CCT, or ATA (P>.40). The ranges of agreement were 0.20 mm, 16.11 mum, and 0.80 mm for ACD, CCT, and ATA, respectively. Regarding IAS, no statistically significant differences were found in the nasal (P = .78) or temporal (P = .63) measurements between devices. However, the range of agreement for nasal (14.3 degrees) and temporal (14.90 degrees) values was relevant, indicating the 2 techniques cannot be used interchangeably for IAS measurement. Excellent intrasession repeatability scores were obtained (CV and ICC). The Artemis 2 and the Visante OCT systems provide equivalent and repeatable measurements of the ACD, CCT, and ATA and can be used interchangeably for these purposes.

Temporal evolution of intraocular pressure elevation after pupillary dilation in pigment dispersion syndrome.

PubMed

Jewelewicz, Daniel A; Radcliffe, Nathan M; Liebmann, Jeffrey; Ritch, Robert

2009-03-01

To report 4 patients with pigment dispersion syndrome (PDS) who had delayed intraocular pressure (IOP) spikes after pharmacologic pupillary dilation. Four patients with a diagnosis of PDS with documented IOP spike after pharmacologic pupillary dilation were included. Study patients were examined before and after pupillary dilation. The amount of pigment present in the anterior chamber and the IOP were measured at hourly intervals. Although maximal pigment liberation occurred immediately after maximal dilation, the IOP continued to elevate for at least 1.5 hours. The increase in IOP after pupillary dilation may not occur simultaneously with maximal pigment liberation but may follow it after the pigment has settled out of the anterior chamber. This has implications for monitoring patients with PDS after dilation to detect and treat rises in IOP.

Factors controlling the structures of magma chambers in basaltic volcanoes

NASA Technical Reports Server (NTRS)

Wilson, L.; Head, James W.

1991-01-01

The depths, vertical extents, and lateral extents of magma chambers and their formation are discussed. The depth to the center of a magma chamber is most probably determined by the density structure of the lithosphere; this process is explained. It is commonly assumed that magma chambers grow until the stress on the roof, floor, and side-wall boundaries exceed the strength of the wall rocks. Attempts to grow further lead to dike propagation events which reduce the stresses below the critical values of rock failure. The tensile or compressive failure of the walls is discussed with respect to magma migration. The later growth of magma chambers is accomplished by lateral dike injection into the country rocks. The factors controlling the patterns of growth and cooling of such dikes are briefly mentioned.

The geochemical and petrological characteristics of prenatal caldera volcano: a case of the newly formed small dacitic caldera, Hijiori, Northeast Japan

NASA Astrophysics Data System (ADS)

Miyagi, Isoji; Kita, Noriko; Morishita, Yuichi

2017-09-01

Evaluating the magma depth and its physical properties is critical to conduct a better geophysical assessment of magma chambers of caldera volcanoes that may potentially cause future volcanic hazards. To understand pre-eruptive conditions of a magma chamber before its first appearance at the surface, this paper describes the case of Hijiori caldera volcano in northeastern Japan, which emerged approximately 12,000 years ago at a place where no volcano ever existed. We estimated the depth, density, bulk modulus, vesicularity, crystal content, and bulk H_2O content of the magma chamber using petrographic interpretations, bulk and microchemical compositions, and thermodynamic calculations. The chemical mass balance calculations and thermodynamic modeling of the erupted magmas indicate that the upper portion of the Hijiori magmatic plumbing system was located at depths between 2 and 4 km, and had the following characteristics: (1) pre-eruptive temperature: about 780 °C; (2) bulk magma composition: 66 ± 1.5 wt% SiO2; (3) bulk magmatic H_2O: approximately 2.5 wt%, and variable characteristics that depend on depth; (4) crystal content: ≤57 vol%; (5) bulk modulus of magma: 0.1-0.8 GPa; (6) magma density: 1.8-2.3 g/cm3; and (7) amount of excess magmatic H_2O: 11-32 vol% or 48-81 mol%. The range of melt water contents found in quartz-hosted melt inclusions (2-9 wt%) suggests the range of depth phenocrysts growth to be wide (2˜13 km). Our data suggest the presence of a vertically elongated magma chamber whose top is nearly solidified but highly vesiculated; this chamber has probably grown and re-mobilized by repeated injections of a small amount of hot dacitic magma originated from the depth.

Width of anterior chamber angle determined by OCT, and correlation to refraction and age in a German working population: the MIPH Eye&Health Study.

PubMed

Vossmerbaeumer, Urs; Schuster, Alexander K; Fischer, Joachim E

2013-12-01

Optical coherence tomography (OCT) of the anterior segment allows quantitative analysis of the geometry of the chamber angle. We performed bilateral spectral-domain OCT measurements in healthy, emmetropic, hyperopic, and myopic subjects to establish correlations between the width of the angle, the refraction, and intraocular pressure of the test persons. Out of 4,617 eyes (2,309 subjects), those with refractive errors of < -4 or > +3 diopters were identified by objective refraction measurement (KR-8800 Kerato-Refractometer, Topcon Inc., Japan) and examined using the anterior segment mode of a spectral-domain 3D OCT-2000 (Topcon Inc., Japan). Non-contact tonometry was performed (CT-80, Topcon Inc., Japan). One hundred and eight eyes of 54 emmetropic subjects (± 0.5 dpt) served as reference group. Previous ocular surgery was exclusion criterion in all groups. Width of the chamber angle was determined using semi-automated software tools and statistical analysis of the data (Pearson correlation, ANOVA with post-hoc test and Bonferroni correction, regression analysis) was performed using SPSS software (SPSS 19.0, Chicago, IL, USA). Six hundred and sixty-eight eyes of 398 persons (292 male, 96 female) were included in the study. Mean hyperopic refraction was +4.24 (+3  to +7.75) dpt, mean myopic refraction was -5.86 (-4 to -11.75) dpt. Valid chamber angle OCT measurements could be obtained from 50 (69.4 %) hyperopic and 400 (71.4 %) myopic eyes meeting the inclusion criteria. The mean width of the chamber angle was determined as 31.8° (range: 13.5 to 45.6, SD 7.49) in the hyperopic group, 40.8° (range: 19.3 to 66.0, SD 8.1) in the myopic group, and 36.3° (range: 21.1 to 51.8, SD 6.8) in the emmetropic reference group. Correlation was highly significant (p > 0.001) between refractive error and the aperture of the chamber angle as measured from OCT. The association of the intraocular pressure and the refraction was also highly significant (p > 0.001) for the three groups. The spectral-domain OCT yielded measurements that could be used for digital analysis of the chamber angle geometry. Our results highlight the correlation between refraction and aperture of the angle in hyperopia and myopia as determined by the 3D OCT-2000: hyperopia is associated with a narrower chamber angle, myopia with a wider aperture of the angle.

Fluid mechanics of the human eye: aqueous humour flow in the anterior chamber.

PubMed

Fitt, A D; Gonzalez, G

2006-01-01

We consider and compare the various different kinds of flow that may take place in the anterior chamber of a human eye. The physical mechanisms responsible for causing such flows may be classified as follows: (i) buoyancy-driven flow arising from the temperature difference between the anterior surface of the cornea and the iris, (ii) flow generated by the aqueous production of the ciliary body, (iii) flow generated by the interaction between buoyancy and gravity while sleeping while sleeping in a face-up position, (iv) flow generated by phakodenesis (lens tremor), (v) flow generated by Rapid Eye Movement (REM) during sleep. Each flow is studied using a traditional fluid mechanics/asymptotic analysis approach. We also assess the veracity of a hypothesis that was recently advanced [see Maurice, D.M., 1998. The Von Sallman Lecture 1996: An ophthalmological explanation of REM sleep. Exp. Eye. Res. 66, 139-145, for details] to suggest that, contrary to previous opinion, the purpose of REM during sleep is to ensure corneal respiration in the absence of the buoyant mixing that routinely takes place due to (i) above during waking conditions.

Association of Baseline Anterior Segment Parameters With the Development of Incident Gonioscopic Angle Closure.

PubMed

Nongpiur, Monisha E; Aboobakar, Inas F; Baskaran, Mani; Narayanaswamy, Arun; Sakata, Lisandro M; Wu, Renyi; Atalay, Eray; Friedman, David S; Aung, Tin

2017-03-01

Baseline anterior segment imaging parameters associated with incident gonioscopic angle closure, to our knowledge, are unknown. To identify baseline quantitative anterior segment optical coherence tomography parameters associated with the development of incident gonioscopic angle closure after 4 years among participants with gonioscopically open angles at baseline. Three hundred forty-two participants aged 50 years or older were recruited to participate in this prospective, community-based observational study. Participants underwent gonioscopy and anterior segment optical coherence tomography imaging at baseline and after 4 years. Custom image analysis software was used to quantify anterior chamber parameters from anterior segment optical coherence tomography images. Baseline anterior segment optical coherence tomography measurements among participants with gonioscopically open vs closed angles at follow-up. Of the 342 participants, 187 (55%) were women and 297 (87%) were Chinese. The response rate was 62.4%. Forty-nine participants (14.3%) developed gonioscopic angle closure after 4 years. The mean age (SD) at baseline of the 49 participants was 62.9 (8.0) years, 15 (30.6%) were men, and 43 (87.8%) were Chinese. These participants had a smaller baseline angle opening distance at 750 µm (AOD750) (0.15 mm; 95% CI, 0.12-0.18), trabecular iris surface area at 750 µm (0.07 mm2; 95% CI, 0.05-0.08), anterior chamber area (30 mm2; 95% CI, 2.27-3.74), and anterior chamber volume (24.32 mm2; 95% CI, 18.20-30.44) (all P < .001). Baseline iris curvature (-0.08; 95% CI, -0.12 to -0.04) and lens vault (LV) measurements (-0.29 mm; 95% CI, -0.37 to -0.21) were larger among these participants ( all P < .001). A model consisting of the LV and AOD750 measurements explained 38% of the variance in gonioscopic angle closure occurring at 4 years, with LV accounting for 28% of this variance. For every 0.1 mm increase in LV and 0.1 mm decrease in AOD750, the odds of developing gonioscopic angle closure was 1.29 (95% CI, 1.07-1.57) and 3.27 (95% CI, 1.87-5.69), respectively. In terms of per SD change in LV and AOD750, this translates to an odds ratio of 2.14 (95% CI, 2.48-12.34) and 5.53 (95% CI, 1.22-3.77), respectively. A baseline LV cut-off value of >0.56 mm had 64.6% sensitivity and 84.0% specificity for identifying participants who developed angle closure. These findings suggest that smaller AOD750 and larger LV measurements are associated with the development of incident gonioscopic angle closure after 4 years among participants with gonioscopically open angles at baseline.

Facts about Glaucoma

MedlinePlus

... Clinical Director Laboratories, Sections and Units Division of Epidemiology and Clinical Applications eyeGENE Research Directors Office Office ... In the front of the eye is a space called the anterior chamber. A clear fluid flows ...

The use of low dose methotrexate in children with chronic anterior and intermediate uveitis.

PubMed

Malik, A R; Pavesio, C

2005-07-01

To assess the efficacy of low dose methotrexate (MTX) therapy for children with chronic anterior and intermediate uveitis. A retrospective case review of 10 children who received MTX for chronic uveitis at a tertiary referral centre was performed. The following data were recorded for each patient: age, sex, race, duration of uveitis, primary diagnosis, anatomical localisation of uveitis, corticosteroid therapy, dose range of MTX, duration of MTX therapy, and side effects of MTX therapy. Several clinical parameters were evaluated to study the effect of MTX. These included visual acuity, anterior chamber inflammation, and topical and oral corticosteroid requirement. After MTX VA of 6/6 or better was present in 100% right eyes and 80% left eyes (p = 0.055 and p = 0.016, respectively). Anterior chamber inflammation decreased in 60% of children after MTX (p = 0.0168). The requirement of topical steroid decreased from a mean of 5.6 times a day before MTX to 1.5 times a day after MTX (p = 0.005). The dose of oral steroid decreased from a mean of 18 mg per day to 2.85 mg per day (p = 0.012). The most common adverse effect was nausea (20%). No patient required discontinuation of MTX because of side effects. MTX is effective and safe for chronic anterior and intermediate uveitis in children. An increase awareness of its efficacy is required among paediatricians and ophthalmologists to prevent sight threatening complication of chronic uveitis and its treatment with long term use of steroids.

Realize multiple hermetic chamber pressures for system-on-chip process by using the capping wafer with diverse cavity depths

NASA Astrophysics Data System (ADS)

Cheng, Shyh-Wei; Weng, Jui-Chun; Liang, Kai-Chih; Sun, Yi-Chiang; Fang, Weileun

2018-04-01

Many mechanical and thermal characteristics, for example the air damping, of suspended micromachined structures are sensitive to the ambient pressure. Thus, micromachined devices such as the gyroscope and accelerometer have different ambient pressure requirements. Commercially available process platforms could be used to fabricate and integrate devices of various functions to reduce the chip size. However, it remains a challenge to offer different ambient pressures for micromachined devices after sealing them by wafer level capping (WLC). This study exploits the outgassing characteristics of the CMOS chip to fabricate chambers of various pressures after the WLC of the Si-above-CMOS (TSMC 0.18 µm 1P5M CMOS process) MEMS process platform. The pressure of the sealed chamber can be modulated by the chamber volume after the outgassing. In other words, the pressure of hermetic sealed chambers can be easily and properly defined by the etching depth of the cavity on an Si capping wafer. In applications, devices sealed with different cavity depths are implemented using the Si-above-CMOS (TSMC 0.18 µm 1P5M CMOS process) MEMS process platform to demonstrate the present approach. Measurements show the feasibility of this simple chamber pressure modulation approach on eight-inch wafers.

Monte Carlo study of si diode response in electron beams.

PubMed

Wang, Lilie L W; Rogers, David W O

2007-05-01

Silicon semiconductor diodes measure almost the same depth-dose distributions in both photon and electron beams as those measured by ion chambers. A recent study in ion chamber dosimetry has suggested that the wall correction factor for a parallel-plate ion chamber in electron beams changes with depth by as much as 6%. To investigate diode detector response with respect to depth, a silicon diode model is constructed and the water/silicon dose ratio at various depths in electron beams is calculated using EGSnrc. The results indicate that, for this particular diode model, the diode response per unit water dose (or water/diode dose ratio) in both 6 and 18 MeV electron beams is flat within 2% versus depth, from near the phantom surface to the depth of R50 (with calculation uncertainty <0.3%). This suggests that there must be some other correction factors for ion chambers that counter-balance the large wall correction factor at depth in electron beams. In addition, the beam quality and field-size dependence of the diode model are also calculated. The results show that the water/diode dose ratio remains constant within 2% over the electron energy range from 6 to 18 MeV. The water/diode dose ratio does not depend on field size as long as the incident electron beam is broad and the electron energy is high. However, for a very small beam size (1 X 1 cm(2)) and low electron energy (6 MeV), the water/diode dose ratio may decrease by more than 2% compared to that of a broad beam.

Anterior Eye Imaging with Optical Coherence Tomography

NASA Astrophysics Data System (ADS)

Huang, David; Li, Yan; Tang, Maolong

The development of corneal and anterior segment optical coherence tomography (OCT) technology has advanced rapidly in recently years. The scan geometry and imaging wavelength are both important choices to make in designing anterior segment OCT systems. Rectangular scan geometry offers the least image distortion and is now used in most anterior OCT systems. The wavelength of OCT light source affects resolution and penetration. An optimal choice of the OCT imaging wavelength (840, 1,050, or 1,310 nm) depends on the application of interest. Newer generation Fourier-domain OCT technology can provide scan speed 100-1000 times faster than the time-domain technology. Various commercial anterior OCT systems are available on the market. A wide spectrum of diagnostic and surgical applications using anterior segment OCT had been investigated, including mapping of corneal and epithelial thicknesses, keratoconus screening, measuring corneal refractive power, corneal surgery planning and evaluation in LASIK, intracorneal ring implantation, assessment of angle closure glaucoma, anterior chamber biometry and intraocular lens implants, intraocular lens power calculation, and eye bank donor cornea screening.

Structure of the southern Juan de Fuca Ridge from seismic reflection records

USGS Publications Warehouse

Morton, Janet L.; Sleep, Norman H.; Normark, William R.; Tompkins, Donald H.

1987-01-01

Twenty-four-channel seismic reflection records were obtained from the axial region of the southern Juan de Fuca Ridge. Two profiles are normal to the strike of the spreading center and intersect the ridge at latitude 44°40′N and 45°05′N; a third profile extends south along the ridge axis from latitude 45°20′N and crosses the Blanco Fracture Zone. Processing of the axial portions of the cross-strike lines resolved a weak reflection centered beneath the axis. The reflector is at a depth similar to seismically detected magma chambers on the East Pacific Rise and a Lau Basin spreading center; we suggest that the reflector represents the top of an axial magma chamber. In the migrated sections the top of the probable magma chamber is relatively flat and 1–2 km wide, and the subbottom depth of the chamber is greater where the depth to the ridge axis is greater.

Intraoperative fracture of phacoemulsification sleeve

PubMed Central

2010-01-01

Background We describe a case of intraoperative fracture of phacoemulsification sleeve during phacoemulsification surgery. Case presentation Phacoemulsification surgery was performed in the left eye of a 58-year-old lady with grade II nuclear sclerosis & grade I cortical cataract. Towards the end of quadrant removal, there was anterior chamber instability with impaired followability of nuclear fragments. The distal part of the fractured sleeve remained inside the anterior chamber upon removal of the phacoemulsification probe. The retained sleeve was retrieved with a pair of forceps through the corneal incision site, which did not require widening. There was no missing fragments retained intraocularly and the patient had an uneventful recovery with vision of 20/25 at three months post-operatively. Conclusion Phacoemulsification sleeve fracture is an uncommon complication. With early identification of this condition and proper management, major complications can be avoided. PMID:21118542

Is anterior chamber lens implantation after intracapsular cataract extraction safe in rural black patients in Africa? A pilot study in KwaZulu-Natal, South Africa.

PubMed

Cook, C D; Evans, J R; Johnson, G J

1998-01-01

There are an estimated 16 million people blind from cataract world-wide. In many areas the routine operation is intracapsular cataract extraction (ICCE). The role of modern anterior chamber (AC) intraocular lenses (IOLs) is being explored, and they have been shown to be safe and successful in Asia. Are they equally safe in rural black African populations? One hundred black patients aged 50 years and over who attended Edendale Hospital were enrolled in a pilot study of insertion of AC IOLs after ICCE. They were followed up for 6 months. With financial remuneration, the follow-up rate at 8 weeks increased from the usual 30% to 72%. At 6 months, 67% of eyes achieved a correlated visual acuity of 6/18 or better. Thirty per cent had persistent uveitis, 16% had peripheral anterior synechiae beyond the points of haptic contact, and 5% had an intraocular pressure greater than 21 mmHg. A randomised trial comparing ICCE with AC IOL and extracapsular cataract extraction with posterior chamber IOL is probably not justified at this time in this population. However, there may be wide variations in the reaction of the eyes of different African ethnic groups to IOLs. In view of the successful use of AC IOLs in Asian eyes, further pilot studies of AC IOLs may be warranted in other parts of Africa where ICCE is the routine procedure.

Dual-wavelength polarimetric glucose sensing in the presence of birefringence and motion artifact using anterior chamber of the eye phantoms

PubMed Central

Pirnstill, Casey W.; Coté, Gerard L.

2013-01-01

Abstract. Noninvasive glucose monitoring is being investigated as a tool for effectively managing diabetes mellitus. Optical polarimetry has emerged as one such method, which can potentially be used to ascertain blood glucose levels by measuring the aqueous humor glucose levels in the anterior chamber of the eye. The key limitation for realizing this technique is the presence of sample noise due to corneal birefringence, which in the presence of motion artifact can confound the glucose signature in the aqueous humor of the eye. We present the development and characterization of a real-time, closed-loop, dual-wavelength polarimetric system for glucose monitoring using both a custom-built plastic eye phantom (in vitro) and isolated rabbit corneas (ex vivo) mounted in an artificial anterior chamber. The results show that the system can account for these noise sources and can monitor physiologic glucose levels accurately for a limited range of motion-induced birefringence. Using the dual-wavelength system in vitro and ex vivo, standard errors were 14.5  mg/dL and 22.4  mg/dL, respectively, in the presence of birefringence with motion. The results indicate that although dual-wavelength polarimetry has a limited range of compensation for motion-induced birefringence, when aligned correctly, it can minimize the effect of time-varying corneal birefringence for a range of motion larger than what has been reported in vivo. PMID:23299516

Anterior Chamber Air Bubble to Achieve Graft Attachment After DMEK: Is Bigger Always Better?

PubMed

Ćirković, Aleksandar; Beck, Christina; Weller, Julia M; Kruse, Friedrich E; Tourtas, Theofilos

2016-04-01

To analyze the influence of the size of the air bubble subsequent to Descemet membrane endothelial keratoplasty (DMEK) surgery on the rate of graft detachment and need for rebubbling, the incidence of pupillary block, and the observed endothelial cell loss. This is a single-center, retrospective, consecutive case series of 74 cases undergoing DMEK and fulfilling the inclusion criteria concerning the size of the air bubble at the end of surgery. Based on the medical records, patients were divided into 2 groups (n = 37, respectively). The first group had an air bubble with a volume of approximately 50% and the second group of approximately 80% of the anterior chamber (AC) volume, respectively. Patients who did not comply with instructions to remain in the supine position until complete resorption of AC air or cases in which difficulties in graft preparation (eg, radial breaks) occurred were excluded from data analysis. The central corneal thickness and endothelial cell density were measured 6 months after surgery. Ten of 37 patients (27.0%) in the 50% air bubble group and 3 of 37 patients (8.1%) in the 80% air bubble group needed 1 rebubbling procedure (P = 0.032). There was no difference between the groups after 6 months regarding endothelial cell density and central corneal thickness. No pupillary block was observed. Larger air bubbles of 80% anterior chamber volume decrease the risk of graft detachment after DMEK with no detrimental effect on the outcome and risk for pupillary block.

Fluid temperature at the corneal endothelium during phacoemulsification: comparison of an ophthalmic viscosurgical device and balanced salt solution using the finite element method.

PubMed

Reepolmaha, Somporn; Limtrakarn, Wiroj; Uthaisang-Tanechpongtamb, Wanlaya; Dechaumphai, Pramote

2010-01-01

The purpose of this study was to estimate and compare the temperatures of two different anterior chamber solutions at the corneal endothelial level during phacoemulsification. An ophthalmic viscosurgical device (OVD) and balanced salt solution (BSS) were compared using the finite element method (FEM). The thermal properties of an OVD (IAL-F) and BSS were studied in an experimental setting. A computer-aided design model of ocular anatomy was created in two dimensions. The phaco needle was considered to be the only source of heat generation. Then, the FEM was used to demonstrate the transient temperature distribution in the two ocular models at 10, 20, 30, 40, 50 and 60 s. In these models, the anterior chamber was filled with IAL-F (IAL-F model) or BSS (BSS model). The heat generation rate of the phaco needle was 0.0004 cal/s/mm(2). The maximum corneal endothelial temperatures for the two models at 60 s were 52.67 and 41.57 degrees C, respectively. The experimental IAL-F model showed fewer changes in temperature for any given time and location. At larger distances from the heat source, less temperature variation was detected. Phacoemulsification is a potential heat-generating procedure performed between the delicate anterior chamber structures. During this procedure, IAL-F protects the endothelium against heat better than BSS. Copyright 2009 S. Karger AG, Basel.

Ocular volumetry using fast high-resolution MRI during visual fixation.

PubMed

Tanitame, K; Sone, T; Miyoshi, T; Tanitame, N; Otani, K; Akiyama, Y; Takasu, M; Date, S; Kiuchi, Y; Awai, K

2013-04-01

Volumetry may be useful for evaluating treatment response and prognosis of intraocular lesions. Phantom, volunteer, and patient studies were performed to determine whether ocular MR volumetry is reproducible. Half-Fourier single-shot RARE and FSPGR sequences at 1.5T with a 76-mm-diameter surface coil were optimized to obtain still ocular images. Volumetry accuracies of each sequence were compared with simulated subretinal phantom volumes. Ocular volumetry was performed in 15 volunteers twice in 1 week by using contiguous axial images of the globes while the subjects stared at a target, and images were acquired in 2 seconds before the subjects were instructed to blink, with this process repeated as necessary. Imaging, intraobserver, and interobserver reproducibility for volumes of the whole eyeball and anterior chamber were assessed. Ocular volumetry was also performed in 6 patients with intraocular tumors before and after treatment. The phantom study demonstrated that measurement error rates with RARE were significantly lower than with FSPGR (P<.01). The volunteer study demonstrated excellent imaging and intraobserver reproducibility of RARE volumetry for whole eyeballs and anterior chambers (P<.01). Although no interobserver differences were observed in anterior chamber volume measurement (P=.33), there was a significant difference between the 2 observers in eyeball volume measurement (P<.01). Follow-up volumetric data were useful for treatment decisions in all patients. Ocular volumetry from contiguous ultrafast RARE images obtained during visual fixation is feasible in volunteer and patient studies and is superior to FSPGR images.

A Novel Method for Measuring Anterior Segment Area of the Eye on Ultrasound Biomicroscopic Images Using Photoshop

PubMed Central

Wu, Ziqiang; Lin, Jialiu; Huang, Jingjing

2015-01-01

Purpose To describe a novel method for quantitative measurement of area parameters in ocular anterior segment ultrasound biomicroscopy (UBM) images using Photoshop software and to assess its intraobserver and interobserver reproducibility. Methods Twenty healthy volunteers with wide angles and twenty patients with narrow or closed angles were consecutively recruited. UBM images were obtained and analyzed using Photoshop software by two physicians with different-level training on two occasions. Borders of anterior segment structures including cornea, iris, lens, and zonules in the UBM image were semi-automatically defined by the Magnetic Lasso Tool in the Photoshop software according to the pixel contrast and modified by the observers. Anterior chamber area (ACA), posterior chamber area (PCA), iris cross-section area (ICA) and angle recess area (ARA) were drawn and measured. The intraobserver and interobserver reproducibilities of the anterior segment area parameters and scleral spur location were assessed by limits of agreement, coefficient of variation (CV), and intraclass correlation coefficient (ICC). Results All of the parameters were successfully measured by Photoshop. The intraobserver and interobserver reproducibilities of ACA, PCA, and ICA were good, with no more than 5% CV and more than 0.95 ICC, while the CVs of ARA were within 20%. The intraobserver and interobserver reproducibilities for defining the spur location were more than 0.97 ICCs. Although the operating times for both observers were less than 3 minutes per image, there was significant difference in the measuring time between two observers with different levels of training (p<0.001). Conclusion Measurements of ocular anterior segment areas on UBM images by Photoshop showed good intraobserver and interobserver reproducibilties. The methodology was easy to adopt and effective in measuring. PMID:25803857

Potential errors in relative dose measurements in kilovoltage photon beams due to polarity effects in plane-parallel ionisation chambers

NASA Astrophysics Data System (ADS)

Dowdell, S.; Tyler, M.; McNamara, J.; Sloan, K.; Ceylan, A.; Rinks, A.

2016-12-01

Plane-parallel ionisation chambers are regularly used to conduct relative dosimetry measurements for therapeutic kilovoltage beams during commissioning and routine quality assurance. This paper presents the first quantification of the polarity effect in kilovoltage photon beams for two types of commercially available plane-parallel ionisation chambers used for such measurements. Measurements were performed at various depths along the central axis in a solid water phantom and for different field sizes at 2 cm depth to determine the polarity effect for PTW Advanced Markus and Roos ionisation chambers (PTW-Freiburg, Germany). Data was acquired for kilovoltage beams between 100 kVp (half-value layer (HVL)  =  2.88 mm Al) and 250 kVp (HVL  =  2.12 mm Cu) and field sizes of 3-15 cm diameter for 30 cm focus-source distance (FSD) and 4  ×  4 cm2-20  ×  20 cm2 for 50 cm FSD. Substantial polarity effects, up to 9.6%, were observed for the Advanced Markus chamber compared to a maximum 0.5% for the Roos chamber. The magnitude of the polarity effect was observed to increase with field size and beam energy but was consistent with depth. The polarity effect is directly influenced by chamber design, with potentially large polarity effects for some plane-parallel ionisation chambers. Depending on the specific chamber used, polarity corrections may be required for output factor measurements of kilovoltage photon beams. Failure to account for polarity effects could lead to an incorrect dose being delivered to the patient.

Correlation Between Corneal Button Size and Intraocular Pressure During Femtosecond Laser-Assisted Keratoplasty.

PubMed

Choi, Mihyun; Lee, Yong Eun; Whang, Woong-Joo; Yoo, Young-Sik; Na, Kyung-Sun; Joo, Choun-Ki

2016-03-01

To evaluate changes in intraocular pressure (IOP) in recipient and donor eyes during femtosecond laser-assisted keratoplasty (FLAK) and to assess for differences in the diameter of trephinated corneal buttons according to changes in pressure. Twenty porcine whole eyes (recipient model) and 20 porcine-corneoscleral rims (donor model) were prepared, and anterior chamber pressures were measured using a fiberoptic sensing device (Opsens, Quebec, Canada) during the femtosecond laser corneal cutting process. To determine the diameter of corneal buttons, 10 porcine whole eyes (recipient model) and 12 corneoscleral rims (donor model) of each baseline IOP were cut with the femtosecond laser programmed to the following pattern: "vertical side cut"; 1200 μm (depth), 8 mm (diameter). Digital photographs were obtained using microscopy and subsequently analyzed. The IOP (mean ± SD) for the recipient model was 10.2 (±0.9) mm Hg at baseline and ranged from 96.6 (±4.5) to ∼138.4 (±3.8) mm Hg during the corneal cutting process. This shows that the maximum IOP during FLAK increased 13.5 times compared with baseline. In the donor model, the mean pressure elevation from baseline artificial anterior chamber (AAC) pressure to corneal cutting was 15.8 (±5.4) mm Hg. This showed a positive correlation with baseline IOP [correlation coefficient (CC) = 0.827, P = 0.006]. As the baseline IOP in the recipient eye increased, trephinated corneal button size was reduced by up to 3.9% in diameter (CC = -0.945, P = 0.015). In addition, in donor eyes, the diameter was decreased by up to 11.7% as the baseline AAC pressure increased (CC = -0.934, P = 0.006). During the FLAK procedure, the IOP increases in both recipient and donor eyes. The diameter of the trephinated donor and recipient corneal buttons was decreased as the initial baseline IOP increased. Ophthalmic surgeons can determine the AAC pressure based on the baseline IOP in the recipient patient.

Short-term effects of intravitreal bevacizumab on cornea and anterior chamber.

PubMed

Güler, Mete; Capkın, Musa; Simşek, Ali; Bilak, Semsettin; Bilgin, Burak; Hakim Reyhan, Ali; Fırat, Müge

2014-10-01

To determine the short-term effects of single-dose intravitreal bevacizumab injection on central corneal thickness (CCT), simulated keratometry (Sim K), anterior chamber depth (ACD), iridocorneal angle (ICA) and intraocular pressure (IOP) measurements. Prospective, nonrandomized, interventional clinical trial. Forty-three eyes of 43 patients aged between 41 and 78 years (average 62 ± 13 years) received an intravitreal injection of 2.5 mg/0.1 mL bevacizumab. Patients who had not undergone additional intravitreal anti-vascular endothelial growth factor therapy within 6 months were included in the study. CCT, Sim K, ACD and ICA measurements were obtained with Sirius Topographer. IOP measurements were taken after topographic measurements with Goldmann applanation tonometer. The CCT, ACD, ICA and IOP measurements were taken before and after 3rd, 15th days and 1st month of intravitreal bevacizumab injection. Pre- and postinjection of 3rd, 15th days and 1st month CCT (p = 0.999), Sim K (p = 0.746), ACD (p = 0.996), ICA (p = 0.632) and IOP (p = 0.707) measurements were not statistically different. Mean CCT (p = 1.000), Sim K (0.972), ACD (p = 0.998), ICA (0.667) and IOP (0.951) values were similar before and after 3rd day of bevacizumab injection. Mean CCT (p = 0.999), Sim K (p = 0.994), ACD (p = 1.000), ICA (p = 0.999) and IOP (p = 1.000) measurements were also similar before and after 15th day of injection. Preinjection and 1st month of postinjection CCT (p = 0.999), Sim K (p = 0.932), ACD (p = 0.998), ICA (p = 1.000) and IOP (p = 0.741) measurements did not change significantly. Single-dose intravitreal bevacizumab injection does not affect CCT, Sim K, ACD, ICA and IOP in short-term period.

Light intensity modulates corneal power and refraction in the chick eye exposed to continuous light.

PubMed

Cohen, Yuval; Belkin, Michael; Yehezkel, Oren; Avni, Isaac; Polat, Uri

2008-09-01

Continuous exposure of chicks to light was shown to result in severe hyperopia, accompanied by anterior segment changes, such as severe corneal flattening. Since rearing chicks in complete darkness results only in mild hyperopia and minor changes in corneal curvature, we hypothesized that light intensity may play a role in the development of refractive changes under continuous light illumination. To test this hypothesis, we examined the effects of rearing chicks under various continuous light intensities. More specifically, we investigated the refractive parameters of the chicks' eyes, and avoided light cycling effects on ocular development. To this end, thirty-eight chicks were reared under 24-h incandescent illumination, at three different light intensities: 10,000 lux (n=13), 500 lux (n=12), and 50 lux (n=13). Their eyes underwent repeated retinoscopy, keratometry, and ultrasound biometry, as well as caliper measurements of enucleated eyes. Both refraction and corneal refractive power were found to be correlated with light intensity. On day 90 after hatching, exposure to light intensities of 10,000, 500, and 50 lux resulted in hyperopia of +11.97+/-3.7 (mean+/-SD) +7.9+/-4.08 and +0.63+/-3.61 diopters (D), respectively. Under those intensities, corneal refractive power was 46.10+/-3.62, 49.72+/-4.16, and 56.88+/-4.92D, respectively. Axial length did not differ significantly among the groups. The vitreous chamber was significantly deeper in the high than in the low-intensity groups. Thus, during the early life of chicks exposed to continuous lighting, light intensity affects the vitreous chamber depth as well as the anterior segment parameters, most notably the cornea. The higher the intensity, the more severe was the corneal flattening observed and the hyperopia that developed, whereas continuous illumination at low intensities resulted in emmetropia. Thus, light intensity is an important factor that should be taken into account when studying refractive development.

Optimization of Variable-Depth Liner Configurations for Increased Broadband Noise Reduction

NASA Technical Reports Server (NTRS)

Jones, M. G.; Watson, W. R.; Nark, D. M.; Schiller, N. H.; Born, J. C.

2016-01-01

This paper employs three acoustic propagation codes to explore variable-depth liner configurations for the NASA Langley Grazing Flow Impedance Tube (GFIT). The initial study demonstrates that a variable impedance can acceptably be treated as a uniform impedance if the spatial extent over which this variable impedance occurs is less than one-third of a wavelength of the incident sound. A constrained optimization study is used to design a variable-depth liner and to select an optimization metric. It also provides insight regarding how much attenuation can be achieved with variable-depth liners. Another optimization study is used to design a liner with much finer chamber depth resolution for the Mach 0.0 and 0.3 test conditions. Two liners are designed based on spatial rearrangement of chambers from this liner to determine whether the order is critical. Propagation code predictions suggest this is not the case. Both liners are fabricated via additive manufacturing and tested in the GFIT for the Mach 0.0 condition. Predicted and measured attenuations compare favorably across the full frequency range. These results clearly suggest that the chambers can be arranged in any order, thus offering the potential for innovative liner designs to minimize depth and weight.

Development of Extended-Depth Swept Source Optical Coherence Tomography for Applications in Ophthalmic Imaging of the Anterior and Posterior Eye

NASA Astrophysics Data System (ADS)

Dhalla, Al-Hafeez Zahir

Optical coherence tomography (OCT) is a non-invasive optical imaging modality that provides micron-scale resolution of tissue micro-structure over depth ranges of several millimeters. This imaging technique has had a profound effect on the field of ophthalmology, wherein it has become the standard of care for the diagnosis of many retinal pathologies. Applications of OCT in the anterior eye, as well as for imaging of coronary arteries and the gastro-intestinal tract, have also shown promise, but have not yet achieved widespread clinical use. The usable imaging depth of OCT systems is most often limited by one of three factors: optical attenuation, inherent imaging range, or depth-of-focus. The first of these, optical attenuation, stems from the limitation that OCT only detects singly-scattered light. Thus, beyond a certain penetration depth into turbid media, essentially all of the incident light will have been multiply scattered, and can no longer be used for OCT imaging. For many applications (especially retinal imaging), optical attenuation is the most restrictive of the three imaging depth limitations. However, for some applications, especially anterior segment, cardiovascular (catheter-based) and GI (endoscopic) imaging, the usable imaging depth is often not limited by optical attenuation, but rather by the inherent imaging depth of the OCT systems. This inherent imaging depth, which is specific to only Fourier Domain OCT, arises due to two factors: sensitivity fall-off and the complex conjugate ambiguity. Finally, due to the trade-off between lateral resolution and axial depth-of-focus inherent in diffractive optical systems, additional depth limitations sometimes arises in either high lateral resolution or extended depth OCT imaging systems. The depth-of-focus limitation is most apparent in applications such as adaptive optics (AO-) OCT imaging of the retina, and extended depth imaging of the ocular anterior segment. In this dissertation, techniques for extending the imaging range of OCT systems are developed. These techniques include the use of a high spectral purity swept source laser in a full-field OCT system, as well as the use of a peculiar phenomenon known as coherence revival to resolve the complex conjugate ambiguity in swept source OCT. In addition, a technique for extending the depth of focus of OCT systems by using a polarization-encoded, dual-focus sample arm is demonstrated. Along the way, other related advances are also presented, including the development of techniques to reduce crosstalk and speckle artifacts in full-field OCT, and the use of fast optical switches to increase the imaging speed of certain low-duty cycle swept source OCT systems. Finally, the clinical utility of these techniques is demonstrated by combining them to demonstrate high-speed, high resolution, extended-depth imaging of both the anterior and posterior eye simultaneously and in vivo.

In vivo real-time rectal wall dosimetry for prostate radiotherapy

PubMed Central

Hardcastle, Nicholas; Cutajar, Dean L.; Metcalfe, Peter E.; Lerch, Michael L. F.; Perevertaylo, Vladimir L.; Tomé, Wolfgang A.; Rosenfeld, Anatoly B.

2010-01-01

Rectal balloons are used in external beam prostate radiotherapy to provide reproducible anatomy and rectal dose reductions. This is an investigation into the combination of a MOSFET radiation detector with a rectal balloon for real time in vivo rectal wall dosimetry. The MOSFET used in the study is a radiation detector that provides a water equivalent depth of measurement of 70μm. Two MOSFETs were combined in a face-to-face orientation. The reproducibility, sensitivity and angular dependence were measured for the dual MOSFET in a 6MV photon beam. The dual MOSFET was combined with a rectal balloon and irradiated with hypothetical prostate treatments in a phantom. The anterior rectal wall dose was measured in real time and compared with the planning system calculated dose. The dual MOSFET showed angular dependence within ± 2.5% in the azimuth and +2.5%/-4% in the polar axes. When compared with an ion chamber measurement in a phantom, the dual MOSFET agreed within 2.5% for a range of radiation path lengths and incident angles. The dual MOSFET had reproducible sensitivity for fraction sizes of 2-10Gy. For the hypothetical prostate treatments the measured anterior rectal wall dose was 2.6% and 3.2% lower than the calculated dose for 3DCRT and IMRT plans. This was expected due to limitations of the dose calculation method used at the balloon cavity interface. A dual MOSFET combined with a commercial rectal balloon was shown to provide reproducible measurements of the anterior rectal wall dose in real time. The measured anterior rectal wall dose agreed with the expected dose from the treatment plan for 3DCRT and IMRT plans. The dual MOSFET could be read out in real time during the irradiation, providing capability for real time dose monitoring of the rectal wall dose during treatment. PMID:20571209

Morphology and histology of the digestive system of the vector leafhopper Psammotettix striatus (L.) (Hemiptera: Cicadellidae).

PubMed

Zhang, Fangmei; Zhang, Chunni; Dai, Wu; Zhang, Yalin

2012-06-01

The vector leafhopper Psammotettix striatus (L.) (Hemiptera: Cicadellidae) is an important economic pest that is a serious threat to wheat in Northwest China, causing great losses to agricultural production by transmitting wheat blue dwarf (WBD) in a persistent circulative manner. Studies on morphology and ultrastructure of the digestive system were made using light, scanning and transmission electron microscopy. The gross morphology of the alimentary canal consists of esophagus (foregut), midgut, hindgut, and special filter chamber. The esophagus, a narrow and slender tube, runs through the whole thorax extending into the filter chamber and connecting with the anterior midgut. The midgut consists of three major regions, anterior, middle and posterior midgut. The anterior midgut is composed of exceptionally thick epithelial cells surrounding a large lumen. Numerous well-developed microvilli occur at the basal region of the epithelium. A large number of electron-lucent and lipid-like vesicles are observed under the microvilli. The posterior midgut is smaller than the anterior midgut in diameter. Numerous different concentric circular bodies are characteristic of the posterior midgut. The hindgut arises from the posterior midgut at the boundary of the filter chamber. It extends downward toward the anus where the hindgut enlarges to form the rectum. The rectum is formed by various cells typical of epithelium, whose nuclei are relatively smaller than those of the midgut. Relatively large muscle cells are present at the well-defined and thick basement membrane. There are two pairs of Malpighian tubules. Numerous mitochondria and lamellar rough endoplasmic reticulum in the cells of the anterior segment of the Malpighian tubules; the sub-anterior segment of the tubules resemble the distal segment which are wave-like, amount vesicles in the cells; numerous tightly packed large vesicles contain two types of brochosomes in the inflated segment of the Malpighian tubules. The salivary system of P. striatus contains one pair of salivary glands, which are made up of the principal and accessory gland. The principal glands are divided into anterior, mid- and posterior lobes. About nineteen acini are observed in the principal glands of P. striatus, and vary in structure and colour. Five cellular types are found in the principal glands by transmission electron microscopy, which are rich in secretory granules, modified in size, electron-dense and shape. Rough endoplasmic reticulum in the shape of vesicular and lamellar, mitochondria and Golgi complexes are observed. The accessory gland has only an oval or a rod-shaped acinus. Copyright © 2012 Elsevier Ltd. All rights reserved.

Genetic covariance between central corneal thickness and anterior chamber volume: a Hungarian twin study.

PubMed

Toth, Georgina Zsofia; Racz, Adel; Tarnoki, Adam Domonkos; Tarnoki, David Laszlo; Szekelyhidi, Zita; Littvay, Levente; Suveges, Ildiko; Nemeth, Janos; Nagy, Zoltan Zsolt

2014-10-01

Few, and inconsistent, studies have showed high heritability of some parameters of the anterior segment of the eye; however, no heritability of anterior chamber volume (ACV) has been reported, and no study has been performed to investigate the correlation between the ACV and central corneal thickness (CCT). Anterior segment measurements (Pentacam, Oculus) were obtained from 220 eyes of 110 adult Hungarian twins (41 monozygotic and 14 same-sex dizygotic pairs; 80% women; age 48.6 ± 15.5 years) obtained from the Hungarian Twin Registry. Age- and sex-adjusted heritability of ACV was 85% (bootstrapped 95% confidence interval; CI: 69% to 93%), and 88% for CCT (CI: 79% to 95%). Common environmental effects had no influence, and unshared environmental factors were responsible for 12% and 15% of the variance, respectively. The correlation between ACV and CCT was negative and significant (r ph = -0.35, p < .05), and genetic factors accounted for the covariance significantly (0.934; CI: 0.418, 1.061) based on the bivariate Cholesky decomposition model. These findings support the high heritability of ACV and central corneal thickness, and a strong genetic covariance between them, which underscores the importance of identification of the specific genetic factors and the family risk-based screening of disorders related to these variables, such as open-angle and also angle closure glaucoma and corneal endothelial alterations.

Evaluation of iridociliary and lenticular elasticity using shear-wave elastography in rabbit eyes.

PubMed

Detorakis, Efstathios T; Drakonaki, Eleni E; Ginis, Harilaos; Karyotakis, Nikolaos; Pallikaris, Ioannis G

2014-01-01

A previous study has employed shear-wave ultrasound elastographic imaging to assess corneal rigidity in an ex-vivo porcine eye model. This study employs the same modality in vivo in a rabbit eye model in order to assess lens, ciliary body and total ocular rigidity changes following the instillation of atropine and pilocarpine. Ten non-pigmented female rabbits were examined. Measurements of the lens, ciliary body and total ocular rigidity as well as lens thickness and anterior chamber depth were taken with the Aixplorer system (SuperSonic Imagine, Aix-en-Provence, France) with the SuperLinear™ SL 15-4 transducer in both eyes at baseline as well as after pilocarpine and atropine instillation. The IOP was also measured with the TonoPen tonometer. Changes in rigidity in the examined areas following atropine instillation were statistically not significant. Ciliary body rigidity was significantly increased whereas lens and total ocular rigidity were significantly reduced following pilocarpine instillation. The decrease in lens rigidity following pilocarpine was significantly associated with the respective increase in ciliary body rigidity. Shear-wave ultrasound elastography can detect in vivo rigidity changes in the anterior segment of the rabbit eye model and may potentially be applied in human eyes, providing useful clinical information on conditions in which rigidity changes play an important role, such as glaucoma, pseudoexfoliation syndrome or presbyopia.

Relationship between postoperative refractive outcomes and cataract density: multiple regression analysis.

PubMed

Ueda, Tetsuo; Ikeda, Hitoe; Ota, Takeo; Matsuura, Toyoaki; Hara, Yoshiaki

2010-05-01

To evaluate the relationship between cataract density and the deviation from the predicted refraction. Department of Ophthalmology, Nara Medical University, Kashihara, Japan. Axial length (AL) was measured in eyes with mainly nuclear cataract using partial coherence interferometry (IOLMaster). The postoperative AL was measured in pseudophakic mode. The AL difference was calculated by subtracting the postoperative AL from the preoperative AL. Cataract density was measured with the pupil dilated using anterior segment Scheimpflug imaging (EAS-1000). The predicted postoperative refraction was calculated using the SRK/T formula. The subjective refraction 3 months postoperatively was also measured. The mean absolute prediction error (MAE) (mean of absolute difference between predicted postoperative refraction and spherical equivalent of postoperative subjective refraction) was calculated. The relationship between the MAE and cataract density, age, preoperative visual acuity, anterior chamber depth, corneal radius of curvature, and AL difference was evaluated using multiple regression analysis. In the 96 eyes evaluated, the MAE was correlated with cataract density (r = 0.37, P = .001) and the AL difference (r = 0.34, P = .003) but not with the other parameters. The AL difference was correlated with cataract density (r = 0.53, P<.0001). The postoperative refractive outcome was affected by cataract density. This should be taken into consideration in eyes with a higher density cataract. (c) 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Relationship between refractive error and ocular biometrics in twin children: the Guangzhou Twin Eye Study.

PubMed

Wang, Decai; Liu, Bin; Huang, Shengsong; Huang, Wenyong; He, Mingguang

2014-09-01

A cross-sectional study was conducted to explore the relationship between refractive error and ocular biometrics in children from the Guangzhou twin eye study. Twin participants aged 7-15 years were selected from Guangzhou Twin Eye Study. Ocular examinations included visual acuity measurement, ocular motility evaluation, autorefraction under cycloplegia, and anterior segment, media, and fundus examination. Axial length (AL), anterior chamber depth (ACD), and corneal curvature radius were measured using partial coherence laser interferometry. A multivariate linear regression model was used for statistical analysis. Twin children from Guangzhou city showed a decreased spherical equivalent with age, whereas both AL and ACD were increased and corneal curvature radius remained unchanged. When adjusted by age and gender, the data from 77% of twins presenting with spherical equivalent changes indicated that these were caused by predictable variables (R2 = 0.77, P < 0.001). Primary factors affecting children's refraction included axial length (β = -0.97,P < 0.001), ACD (β = 0.33, P < 0.001), and curvature radius (β = 2.10, P < 0.001). Girls had a higher tendency for myopic status than did boys (β = -0.26, P < 0.001). Age exerted no effect upon the changes in refraction (β = -0.01, P = 0.25). Refraction is correlated with ocular biometrics. Refractive status is largely determined by axial length as the major factor.

On the acoustic wedge design and simulation of anechoic chamber

NASA Astrophysics Data System (ADS)

Jiang, Changyong; Zhang, Shangyu; Huang, Lixi

2016-10-01

This study proposes an alternative to the classic wedge design for anechoic chambers, which is the uniform-then-gradient, flat-wall (UGFW) structure. The working mechanisms of the proposed structure and the traditional wedge are analyzed. It is found that their absorption patterns are different. The parameters of both structures are optimized for achieving minimum absorber depth, under the condition of absorbing 99% of normal incident sound energy. It is found that, the UGFW structure achieves a smaller total depth for the cut-off frequencies ranging from 100 Hz to 250 Hz. This paper also proposes a modification for the complex source image (CSI) model for the empirical simulation of anechoic chambers, originally proposed by Bonfiglio et al. [J. Acoust. Soc. Am. 134 (1), 285-291 (2013)]. The modified CSI model considers the non-locally reactive effect of absorbers at oblique incidence, and the improvement is verified by a full, finite-element simulation of a small chamber. With the modified CSI model, the performance of both decorations with the optimized parameters in a large chamber is simulated. The simulation results are analyzed and checked against the tolerance of 1.5 dB deviation from the inverse square law, stipulated in the ISO standard 3745(2003). In terms of the total decoration depth and anechoic chamber performance, the UGFW structure is better than the classic wedge design.

The use of low dose methotrexate in children with chronic anterior and intermediate uveitis

PubMed Central

Malik, A R; Pavesio, C

2005-01-01

Aim: To assess the efficacy of low dose methotrexate (MTX) therapy for children with chronic anterior and intermediate uveitis. Methods: A retrospective case review of 10 children who received MTX for chronic uveitis at a tertiary referral centre was performed. The following data were recorded for each patient: age, sex, race, duration of uveitis, primary diagnosis, anatomical localisation of uveitis, corticosteroid therapy, dose range of MTX, duration of MTX therapy, and side effects of MTX therapy. Several clinical parameters were evaluated to study the effect of MTX. These included visual acuity, anterior chamber inflammation, and topical and oral corticosteroid requirement. Results: After MTX VA of 6/6 or better was present in 100% right eyes and 80% left eyes (p = 0.055 and p = 0.016, respectively). Anterior chamber inflammation decreased in 60% of children after MTX (p = 0.0168). The requirement of topical steroid decreased from a mean of 5.6 times a day before MTX to 1.5 times a day after MTX (p = 0.005). The dose of oral steroid decreased from a mean of 18 mg per day to 2.85 mg per day (p = 0.012). The most common adverse effect was nausea (20%). No patient required discontinuation of MTX because of side effects. Conclusion: MTX is effective and safe for chronic anterior and intermediate uveitis in children. An increase awareness of its efficacy is required among paediatricians and ophthalmologists to prevent sight threatening complication of chronic uveitis and its treatment with long term use of steroids. PMID:15965154

Safety and efficacy of fibrin glue versus infinity suture in SICS with extended scleral flap

PubMed Central

Ambastha, Anita; Kusumesh, Rakhi; Bhasker, Gyan; Sinha, Bibhuti Prassan

2018-01-01

Purpose: To study the safety and efficacy of biologic fibrin glue (FG) in comparison with infinity suture in SICS with compromised scleral flap. Methods: A retrospective comparative study of patients who were treated with FG (Group A) with 10–0 nylon (Group B) as sealing agent for intraoperative compromised tunnels in SICS. Parameters noted were postoperative inflammation, wound integrity, anterior chamber (AC) depth, intraocular pressure (IOP), and surgically induced astigmatism (SIA) at postoperative day 1, 4 weeks, 6 weeks, and 6 months, respectively. Epi Info 7 software and SIA calculator, Version 2.1 were used to analyze the result. Results: We reviewed the two groups of 18 patients each and noted that there was no statistically significant difference in postoperative inflammation (P > 0.05), AC depth (P > 0.05), and IOP (P > 0.05) between both groups at each postoperative visit. One patient in Group A showed postoperative shallow AC and subconjunctival bleb. Exposed sutures causing foreign body sensation had to be removed in five patients in Group B. At the end of 6-month postoperative period, no statistically significant difference was found in SIA (P = 0.92) between the two groups. Conclusion: Biologic FG can be safely used in securing the compromised scleral incisions in SICS. It also avoids suture-related complications. PMID:29676309

Using continuous intraoperative optical coherence tomography measurements of the aphakic eye for intraocular lens power calculation.

PubMed

Hirnschall, Nino; Norrby, Sverker; Weber, Maria; Maedel, Sophie; Amir-Asgari, Sahand; Findl, Oliver

2015-01-01

To include intraoperative measurements of the anterior lens capsule of the aphakic eye into the intraocular lens power calculation (IPC) process and to compare the refractive outcome with conventional IPC formulae. In this prospective study, a prototype operating microscope with an integrated continuous optical coherence tomography (OCT) device (Visante attached to OPMI VISU 200, Carl Zeiss Meditec AG, Germany) was used to measure the anterior lens capsule position after implanting a capsular tension ring (CTR). Optical biometry (intraocular lens (IOL) Master 500) and ACMaster measurements (Carl Zeiss Meditec AG, Germany) were performed before surgery. Autorefraction and subjective refraction were performed 3 months after surgery. Conventional IPC formulae were compared with a new intraoperatively measured anterior chamber depth (ACD) (ACDIntraOP) partial least squares regression (PLSR) model for prediction of the postoperative refractive outcome. In total, 70 eyes of 70 patients were included. Mean axial eye length (AL) was 23.3 mm (range: 20.6-29.5 mm). Predictive power of the intraoperative measurements was found to be slightly better compared to conventional IOL power calculations. Refractive error dependency on AL for Holladay I, HofferQ, SRK/T, Haigis and ACDintraOP PLSR was r(2)=-0.42 (p<0.0001), r(2)=-0.5 (p<0.0001), r(2)=-0.34 (p=0.010), r(2)=-0.28 (p=0.049) and r(2)<0.001 (p=0.866), respectively, ACDIntraOP measurements help to better predict the refractive outcome and could be useful, if implemented in fourth-generation IPC formulae. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Lamina cribrosa position and Bruch's membrane opening differences between anterior ischemic optic neuropathy and open-angle glaucoma.

PubMed

Rebolleda, Gema; Pérez-Sarriegui, Ane; Díez-Álvarez, Laura; De Juan, Victoria; Muñoz-Negrete, Francisco J

2018-06-01

To compare the optic nerve head morphology among primary open-angle glaucoma, non-arteritic anterior ischemic optic neuropathy eyes, their fellow healthy eyes and control eyes, using spectral-domain optical coherence tomography with enhanced depth imaging. Observational cross-sectional study including 88 eyes of 68 patients. In this study, 23 non-arteritic anterior ischemic optic neuropathy eyes, 17 fellow unaffected eyes, 25 primary open-angle glaucoma eyes, and 23 age-matched control eyes were included. Peripapillary retinal nerve fiber layer thickness and optic disk area were evaluated. Bruch's membrane opening diameter, optic cup depth, anterior lamina cribrosa depth, and prelaminar tissue thickness were assessed. Non-arteritic anterior ischemic optic neuropathy and primary open-angle glaucoma eyes had similar visual field mean deviation and peripapillary retinal nerve fiber layer thickness (P = 0.6 and P = 0.56, respectively). Bruch's membrane opening diameter was significantly larger in primary open-angle glaucoma eyes than in control eyes (P = 0.02). Lamina cribrosa and disk cup were deeper in eyes with primary open-angle glaucoma than both control and non-arteritic anterior ischemic optic neuropathy eyes (P < 0.001). Prelaminar tissue thickness was significantly thinner in primary open-angle glaucoma eyes than in non-arteritic anterior ischemic optic neuropathy eyes (P < 0.001). Lamina cribrosa was shallower in both non-arteritic anterior ischemic optic neuropathy and unaffected fellow eyes compared to healthy eyes (P < 0.001 and P = 0.04, respectively). No differences were found in the optic disk area. A forward lamina cribrosa placement and not a smaller disk could be involved in the pathogenesis of non-arteritic anterior ischemic optic neuropathy. A significantly larger Bruch's membrane opening diameter was found in primary open-angle glaucoma eyes compared with control eyes. This issue has clinical implications because Bruch's membrane opening has been considered a stable reference for disk-related measures.

SU-F-T-582: Small Field Dosimetry in Radiosurgery Collimators with a Stealth Chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azcona, J; Barbes, B

2016-06-15

Purpose: The extraction of a reference signal for measuring small fields in scanning mode can be problematic. In this work we describe the use of a transmission chamber in small field dosimetry for radiosurgery collimators and compare TMR curves obtained with stereotactic diode and microionization chamber. Methods: Four radiosurgery cones of diameters 5, 10, 12.5, and 15mm supplied by Elekta Medical were commissioned in a 6MV FFF beam from an Elekta Versa linac. A transmission chamber manufactured by IBA (Stealth chamber) was attached to the lower part of the collimators and used for PDD and profile measurements in scanning modemore » with a Scanditronix stereotactic diode. It was also used for centering the stereotactic diode in the water tank to measure TMR and output factors, by integrating the signal. TMR measurements for all collimators and the OF for the largest collimator were also acquired on a polystyrene PTW 29672 phantom with a PTW PinPoint 3D chamber 0.016 cm3 volume. Results: Measured TMR with diode and microionization chamber agreed very well with differences larger than 1% only for depths above 15cm, except the smaller collimator, for which differences were always smaller than 2%. Calculated TMR were significantly different (up to 7%) from measured TMR. The differences are attributed to the change in response of the diode with depth, because the effective field aperture varies with depth. Furthermore, neglecting the ratio of phantom-scatter factors in the conversion formula also contributes to this difference. OF measured with diode and chamber showed a difference of 3.5%. Conclusion: The transmission chamber overcomes the problem of extracting a reference signal and is of great help for small field commissioning. Calculating TMR from PDD is strongly discouraged. Good agreement was found when comparing measurements of TMR with stereotactic diode in water with measurements with microionization chamber in polystyrene.« less

Comparison of peristaltic and Venturi pumps in bimanual microincisional cataract surgery.

PubMed

Karaguzel, Hande; Karalezli, Aylin; Aslan, Bekir Sitki

2009-12-01

Comparison of peristaltic and Venturi pumps in bimanual microincision phacoemulsification on the success of the cataract surgery by using sleeveless phaco tip. Bimanual microincision phacoemulsification was done in 49 eyes using a 1.4-mm temporal clear corneal incision. A peristaltic pump was used in 23 eyes, and a Venturi pump was used in 26 eyes for phacoemulsification. Intraoperative complications, anterior chamber stability, and mean duration of surgery were recorded. Duration of surgery was shorter in the Venturi pump group. Anterior chamber stability could not be established in 17 eyes in the peristaltic pump group; it was established in all eyes in the Venturi pump group. Corneal burns were observed in two eyes in the peristaltic pump group and no eyes in the Venturi pump group. Use of a Venturi pump system and a vented gas-forced infusion system can significantly shorten surgery time and reduce risk of thermal burns.

Non-invasive glucose monitor

NASA Technical Reports Server (NTRS)

Lambert, James L. (Inventor); Borchert, Mark S. (Inventor)

2001-01-01

A non-invasive method for determining blood level of an analyte of interest, such as glucose, comprises: generating an excitation laser beam (e.g., at a wavelength of 700 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor in the anterior chamber is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated aqueous humor; and then determining the blood glucose level (or the level of another analyte of interest) for the subject from the Raman spectrum. Preferably, the detecting step is followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing method is also disclosed.

[Unilateral iritis by cysticercal larva in the anterior chamber].

PubMed

Schmidt, U; Klauss, V; Stefani, F H

1990-01-01

An 8-year-old girl complained of progressive pain, visual loss and photophobia in her right eye for 1 week. Treatment with local steroids for acute iritis had not been successful. Slitlamp examination revealed a marked cellular and fibrinous inflammatory reaction of the anterior chamber and a whitish, fibrin-like structure on the surface of the iris. There was mild serum eosinophilia and leucocytosis. The suspected organic material was removed surgically. By light and electron microscopy, parts of the wall of a helminthic parasite were discovered, anatomically consistent with the diagnosis of an immature stage of Taenia solium found in cysticercosis. Such cases of intra-ocular parasitosis are described very rarely but might still occur, although there is no history of suspicious typical exposition to parasites. It is important to know that eosinophilia may be insignificant or even absent and that complete surgical removal will be the only successful treatment.

Reversal of retinal and optic disc ischemia in a patient with sickle cell trait and glaucoma secondary to traumatic hyphema.

PubMed

Wax, M B; Ridley, M E; Magargal, L E

1982-07-01

A 14-year-old black boy with sickle cell trait, who sustained a traumatic hyphema, developed moderately elevated intraocular pressure that failed to respond to carbonic anhydrase inhibitors and osmotic agents. On the tenth postinjury day, a sudden increased cupping of the optic disc and partial central retinal artery obstruction caused painless loss of vision. Reversal of the cupping, the retinal ischemia, and the intraocular pressure was documented following anterior chamber paracentesis, and visual acuity returned to 6/6. Pathophysiology of the posterior ischemia is discussed. This case documents the potentially debilitating course of traumatic hyphema in "benign" sickle cell trait and its avoidance with proper management. The authors endorse recent suggestions for careful observation of any sickle cell patient with traumatic hyphema, and recommend anterior chamber paracentesis, supplemental oxygen, and avoidance of osmotic agents, if secondary glaucoma develops following the initial trauma.

Evaluation of eyes with relative pupillary block by indentation ultrasound biomicroscopy gonioscopy.

PubMed

Matsunaga, Koichi; Ito, Kunio; Esaki, Koji; Sugimoto, Kota; Sano, Toru; Miura, Katsuya; Sasoh, Mikio; Uji, Yukitaka

2004-03-01

To investigate changes in anterior chamber angle configuration with indentation ultrasound biomicroscopy gonioscopy of relative pupillary block (RPB). Cross-sectional study. This study included 26 eyes of 26 patients with RPB. We determined angle opening distance 500 and angle recess area using indentation ultrasound biomicroscopy gonioscopy and compared a small-sized standard eye cup with a new eye cup with an area for inducing pressure. Indentation ultrasound biomicroscopy images documented concavity of the iris in eyes with RPB. Both the new and the small standard eye cups widened the anterior chamber angle significantly (P <.0001) without causing corneal damage. Angle changes were significantly greater for the new eye cup design. Indentation ultrasound biomicroscopy gonioscopy is a useful technique for observation and diagnosis of RPB. Using a small standard or the newly designed eye cup, the procedure can be performed easily and without causing corneal damage.

Fractured Anterior Chamber Intraocular Lens (ACIOL) Complicating Nd: YAG Laser for Peripheral Iridotomy.

PubMed

Farah, Edgard; Koutsandrea, Chryssanthi; Papaefthimiou, Ioannis; Papaconstantinou, Dimitris; Georgalas, Ilias

2013-01-01

Laser peripheral iridotomy is the procedure of choice for the treatment of angle-closure glaucoma caused by relative or absolute pupillary block. Nd: YAG laser iridotomy has been reported to have several complications such as Iris bleeding, hyphema, transient IOP elevation, intraocular inflammation, choroidal, retinal detachment and vitreous hemorrhage. We report a case of a 74 year old lady on anticoagulant treatment who developed pupillary block and angle closure glaucoma after cataract surgery and anterior chamber intraocular lens (ACIOL) insertion complicated with intraoperative bleeding. The patient was treated with Nd: YAG laser iridotomy , however, the ACIOL was inadvertently fractured after a single shot of laser and it had to be replaced. Although the incidence is rare. Ophthalmologists and Opticians should be aware that an ACIOL may be fractured even after a single Nd:YAG laser shot and avoid to perform it close to the ACIOL. Pretreatment counseling should include this rare complication.

Evaluation of Intraocular Inflammation with Laser Flare Photometry in Behçet Uveitis.

PubMed

Yalcindag, Fatime Nilufer; Bingol Kiziltunc, Pinar; Savku, Esra

2017-02-01

To evaluate the association between intraocular inflammation and laser flare photometry measurements in Behçet disease. In total, 45 patients were included in the study. The retrospective chart reviews of patients were performed. The flare levels were compared with the grade of anterior chamber cells, the presence of vitreous cells, the complications of uveitis, and fluorescein angiography scores. The attack group had higher flare intensity; the flare levels were higher in both groups compared with the values of healthy controls. The flare levels were related to the grade of the anterior chamber cells, the presence of vitreous cells and the fluorescein angiography scores. Patients with optic atrophy and/or maculopathy also had higher values. Higher flare values were correlated with poor vision. Laser flare photometry may reduce the necessity of fluorescein angiography in monitoring subclinical inflammation and may be an indicator of posterior segment activity when fluorescein angiography is not applicable.

Interictal spike detection comparing subdural and depth electrodes during electrocorticography.

PubMed

Privitera, M D; Quinlan, J G; Yeh, H S

1990-11-01

We compared the ability of subdural and depth electrodes to detect and localize interictal epileptiform discharges (IEDs) in the temporal lobe. Sixteen patients had simultaneous intraoperative recordings with depth and subdural electrodes while undergoing anterior temporal lobe resections under local anesthesia for medically intractable seizures. IEDs that were focal (detected at just 1 or 2 electrode contacts) typically registered at the nearest contact, regardless of type. IEDs that were regional (engaging more than 2 electrode contacts) typically appeared simultaneously at both electrode types. Neither method was better able to indicate whether an IED was mesial or lateral, posterior or anterior. Subdural and depth electrodes seem to provide complementary information on the location of IEDs within the temporal lobe.

Eliminating impingement optimizes patellar biomechanics in high knee flexion.

PubMed

Tang, Qi-heng; Zhou, Yi-xin; Tang, Jing; Shao, Hong-yi; Wang, Guang-zhi

2010-08-01

We investigated the impact of eliminating the impingement between extensor mechanism and tibial insert on patellar tracking and patellar ligament tension in high knee flexion. Six cadaveric specimens were tested on an Oxford-type testing rig. The Genesis II knee system was implanted into each specimen knee with the traditional tibial insert and high-flex insert successively. Compared to traditional insert, the high-flex insert was characterized with a chambered anterior post and a chambered anterior lip which eliminates patella-post and patellar ligament-anterior lip impingements. The patella was tracked with an NDI Optotrak Certus system. The patellar ligament tension was measured using a NKB S-type tension transducer. There was a decrease of resultant patellar translation relative to the femur with statistically significant (P<0.05) at 90 degrees to 150 degrees of knee flexion and a decrease of patellar ligament tension with statistical significance (P<0.05) at 100 degrees, 120 degrees, 130 degrees, and 140 degrees of flexion using high-flex insert compared to traditional insert. Eliminating the impingement between extensor mechanism and implant in high knee flexion altered patellar tracking and reduced patellar ligament tension, which would facilitate high knee flexion.

Dodick laser phacolysis: thermal effects.

PubMed

Alzner, E; Grabner, G

1999-06-01

To gather experimental data on whether Dodick laser phacolysis leads to corneal or scleral burns. The Eye Department, County Hospital Salzburg, Salzburg, Austria. The study was done using a pulsed neodymium:YAG (Nd:YAG) laser with a wavelength of 1064 nm; energy, 10 mJ; and duration of pulses, 14 ns. The light pulse is carried by a 400 microns quartz fiber to the laser phacolysis probe. The laser light hits a titanium target inside the tip, causing an optical breakdown and thus a shock wave. The generation of both plasma and the shock disrupt the nuclear material. The temperature at the ultrasonic phaco and laser phacolysis tip was measured under air and balanced salt solution (BSS) in a test chamber and in the anterior chambers of eye-bank eyes. Ultrasonic phacoemulsification led to a difference in temperature up to 55.3 degrees C under air, 12 degrees C in BSS, and 10.9 degrees C in the anterior chamber. There was no clinical significant heat generated by the laser phacolysis tip. This initial in vitro study demonstrates that the well-known risk of the tissue heating (i.e., phaco burn) does not occur with Dodick laser phacolysis, even when the irrigation flow is slow or discontinued.

An inverse method to determine the mechanical properties of the iris in vivo

PubMed Central

2014-01-01

Background Understanding the mechanical properties of the iris can help to have an insight into the eye diseases with abnormalities of the iris morphology. Material parameters of the iris were simply calculated relying on the ex vivo experiment. However, the mechanical response of the iris in vivo is different from that ex vivo, therefore, a method was put forward to determine the material parameters of the iris using the optimization method in combination with the finite element method based on the in vivo experiment. Material and methods Ocular hypertension was induced by rapid perfusion to the anterior chamber, during perfusion intraocular pressures in the anterior and posterior chamber were record by sensors, images of the anterior segment were captured by the ultrasonic system. The displacement of the characteristic points on the surface of the iris was calculated. A finite element model of the anterior chamber was developed using the ultrasonic image before perfusion, the multi-island genetic algorithm was employed to determine the material parameters of the iris by minimizing the difference between the finite element simulation and the experimental measurements. Results Material parameters of the iris in vivo were identified as the iris was taken as a nearly incompressible second-order Ogden solid. Values of the parameters μ1, α1, μ2 and α2 were 0.0861 ± 0.0080 MPa, 54.2546 ± 12.7180, 0.0754 ± 0.0200 MPa, and 48.0716 ± 15.7796 respectively. The stability of the inverse finite element method was verified, the sensitivity of the model parameters was investigated. Conclusion Material properties of the iris in vivo could be determined using the multi-island genetic algorithm coupled with the finite element method based on the experiment. PMID:24886660

Contribution of Different Anatomical and Physiologic Factors to Iris Contour and Anterior Chamber Angle Changes During Pupil Dilation: Theoretical Analysis

PubMed Central

Jouzdani, Sara; Amini, Rouzbeh; Barocas, Victor H.

2013-01-01

Purpose. To investigate the contribution of three anatomical and physiologic factors (dilator thickness, dynamic pupillary block, and iris compressibility) to changes in iris configuration and anterior chamber angle during pupil dilation. Methods. A mathematical model of the anterior segment based on the average values of ocular dimensions was developed to simulate pupil dilation. To change the pupil diameter from 3.0 to 5.4 mm in 10 seconds, active dilator contraction was applied by imposing stress in the dilator region. Three sets of parameters were varied in the simulations: (1) a thin (4 μm, 1% of full thickness) versus a thick dilator (covering the full thickness iris) to quantify the effects of dilator anatomy, (2) in the presence (+PB) versus absence of pupillary block (−PB) to quantify the effect of dynamic motion of aqueous humor from the posterior to the anterior chamber, and (3) a compressible versus an incompressible iris to quantify the effects of iris volume change. Changes in the apparent iris–lens contact and angle open distance (AOD500) were calculated for each case. Results. The thin case predicted a significant increase (average 700%) in iris curvature compared with the thick case (average 70%), showing that the anatomy of dilator plays an important role in iris deformation during dilation. In the presence of pupillary block (+PB), AOD500 decreased 25% and 36% for the compressible and incompressible iris, respectively. Conclusions. Iris bowing during dilation was driven primarily by posterior location of the dilator muscle and by dynamic pupillary block, but the effect of pupillary block was not as large as that of the dilator anatomy according to the quantified values of AOD500. Incompressibility of the iris, in contrast, had a relatively small effect on iris curvature but a large effect on AOD500; thus, we conclude that all three effects are important. PMID:23482467

[Hymenoptera stings in eyeball--clinical symptoms, patomechanism and treatment].

PubMed

Cichocka-Jarosz, Ewa; Weglarz, Monika; Romanowska-Dixon, Bozena

2009-01-01

Eyeball is a rare stings location additionally with very special immunology response, with no systemic anaphylactic reactions. The ACAID (Anterior Chamber Associated Immune Deviation) phenomenon causes a special immunology privilege of the eyeball, which prevents late immunological answer reaction and destruction processes of the anterior part of the eye. In case that sting penetrates the eyeball local allergic reaction can appear despite ACAID phenomenon. Adequate treatment is necessary for those patients. It can lead to permanent visual acuity deterioration.

Fine crustal and uppermost mantle S-wave velocity structure beneath the Tengchong volcanic area inferred from receiver function and surface-wave dispersion: constraints on magma chamber distribution

NASA Astrophysics Data System (ADS)

Li, Mengkui; Zhang, Shuangxi; Wu, Tengfei; Hua, Yujin; Zhang, Bo

2018-03-01

The Tengchong volcanic area is located in the southeastern margin of the collision zone between the Indian and Eurasian Plates. It is one of the youngest intraplate volcano groups in mainland China. Imaging the S-wave velocity structure of the crustal and uppermost mantle beneath the Tengchong volcanic area is an important means of improving our understanding of its volcanic activity and seismicity. In this study, we analyze teleseismic data from nine broadband seismic stations in the Tengchong Earthquake Monitoring Network. We then image the crustal and uppermost mantle S-wave velocity structure by joint analysis of receiver functions and surface-wave dispersion. The results reveal widely distributed low-velocity zones. We find four possible magma chambers in the upper-to-middle crust and one in the uppermost mantle. The chamber in the uppermost mantle locates in the depth range from 55 to 70 km. The four magma chambers in the crust occur at different depths, ranging from the depth of 7 to 25 km in general. They may be the heat sources for the high geothermal activity at the surface. Based on the fine crustal and uppermost mantle S-wave velocity structure, we propose a model for the distribution of the magma chambers.

Identification of Therapeutic Targets of Inflammatory Monocyte Recruitment to Modulate the Allogeneic Injury to Donor Cornea.

PubMed

Lapp, Thabo; Zaher, Sarah S; Haas, Carolin T; Becker, David L; Thrasivoulou, Chris; Chain, Benjamin M; Larkin, Daniel F P; Noursadeghi, Mahdad

2015-11-01

We sought to test the hypothesis that monocytes contribute to the immunopathogenesis of corneal allograft rejection and identify therapeutic targets to inhibit monocyte recruitment. Monocytes and proinflammatory mediators within anterior chamber samples during corneal graft rejection were quantified by flow cytometry and multiplex protein assays. Lipopolysaccharide or IFN-γ stimulation of monocyte-derived macrophages (MDMs) was used to generate inflammatory conditioned media (CoM). Corneal endothelial viability was tested by nuclear counting, connexin 43, and propidium iodide staining. Chemokine and chemokine receptor expression in monocytes and MDMs was assessed in microarray transcriptomic data. The role of chemokine pathways in monocyte migration across microvascular endothelium was tested in vitro by chemokine depletion or chemokine receptor inhibitors. Inflammatory monocytes were significantly enriched in anterior chamber samples within 1 week of the onset of symptoms of corneal graft rejection. The MDM inflammatory CoM was cytopathic to transformed human corneal endothelia. This effect was also evident in endothelium of excised human cornea and increased in the presence of monocytes. Gene expression microarrays identified monocyte chemokine receptors and cognate chemokines in MDM inflammatory responses, which were also enriched in anterior chamber samples. Depletion of selected chemokines in MDM inflammatory CoM had no effect on monocyte transmigration across an endothelial blood-eye barrier, but selective chemokine receptor inhibition reduced monocyte recruitment significantly. We propose a role for inflammatory monocytes in endothelial cytotoxicity in corneal graft rejection. Therefore, targeting monocyte recruitment offers a putative novel strategy to reduce donor endothelial cell injury in survival of human corneal allografts.

Pharmacologically and Edinger-Westphal stimulated accommodation in rhesus monkeys does not rely on changes in anterior chamber pressure.

PubMed

He, Lin; Wendt, Mark; Glasser, Adrian

2014-08-01

This study was undertaken to understand the role of anterior chamber pressure (ACP) during pharmacological and Edinger-Westphal (EW) stimulated accommodation in anesthetized monkeys. Experiments were performed on one iridectomized eye each of 7 anesthetized adolescent rhesus monkeys. Accommodation was induced by EW stimulation (n = 2) and intravenous administration of 0.25-4.0 mg/kg pilocarpine (n = 6). Accommodative refractive and biometric changes were measured with continuous 60 Hz infrared photorefraction (n = 6) and 100 Hz A-scan ultrasound biometry (n = 1). An ocular perfusion system was used to measure and manipulate ACP. Pressure was recorded via a 27-gauge needle in the anterior chamber connected to a pressure transducer (n = 7). The needle was also connected to a fluid reservoir to allow ACP to be manipulated and clamped (n = 4) by raising or lowering the fluid reservoir. In all six pharmacologically stimulated monkeys ACP increased during accommodation, from 0.70 to 2.38 mmHg, four of which showed pressure decreases preceding the pressure increases. Two eyes also showed increases in ACP during EW-stimulated accommodation of 2.8 and 7.2 mmHg. ACP increased with increasing EW stimulus amplitudes (n = 2). Clamping or externally manipulating ACP had no effect on resting refraction or on EW and pharmacologically stimulated accommodation in four eyes. The results show that EW stimulated and pharmacologically stimulated accommodation do not rely on ACP in rhesus monkeys. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of a micro-mechanical valve in a novel glaucoma implant.

PubMed

Siewert, Stefan; Schultze, Christine; Schmidt, Wolfram; Hinze, Ulf; Chichkov, Boris; Wree, Andreas; Sternberg, Katrin; Allemann, Reto; Guthoff, Rudolf; Schmitz, Klaus-Peter

2012-10-01

This paper describes methods for design, manufacturing and characterization of a micro-mechanical valve for a novel glaucoma implant. The implant is designed to drain aqueous humour from the anterior chamber of the eye into the suprachoroidal space in case of an elevated intraocular pressure (IOP). In contrast to any existing glaucoma drainage device (GDD), the valve mechanism is located in the anterior chamber and there, surrounded by aqueous humour, immune to fibrosis induced failure. For the prevention of hypotony the micro-mechanical valve is designed to open if the physiological pressure difference between the anterior chamber and the suprachoroidal space in the range of 0.8 mmHg to 3.7 mmHg is exceeded. In particular the work includes: (i) manufacturing and morphological characterization of polymer tubing, (ii) mechanical material testing as basis for (iii) the design of micro-mechanical valves using finite element analysis (FEA), (iv) manufacturing of microstent prototypes including micro-mechanical valves by femtosecond laser micromachining and (v) the experimental fluid-mechanical characterization of the manufactured microstent prototypes with regard to valve opening pressure. The considered materials polyurethane (PUR) and silicone (SIL) exhibit low elastic modulus and high extensibility. The unique valve design enables a low opening pressure of micro-mechanical valves. An ideal valve design for PUR and SIL with an experimentally determined opening pressure of 2 mmHg and 3.7 mmHg is identified. The presented valve approach is suitable for the inhibition of hypotony as a major limitation of today's GDD and will potentially improve the minimally invasive treatment of glaucoma.

Staphylococcus Alpha-Toxin Action on the Rabbit Iris: Toxic Effects and Their Inhibition.

PubMed

Arana, Angela M; Bierdeman, Michael A; Balzli, Charles L; Tang, Aihua; Caballero, Armando R; Patel, Rupesh; O'Callaghan, Richard J

2015-01-01

Staphylococcus aureus infection of the anterior chamber can occur after cataract surgery, causing inflammation and extensive damage to the iris. Alpha-toxin, the most potent S. aureus corneal toxin, was tested as a possible mediator of damage to the iris, and alpha-toxin anti-serum and a chemical toxin inhibitor were tested as potential pathology-reducing agents. The hemolytic activity of alpha-toxin and its inhibition by a chemical inhibitor or anti-serum were quantified in vitro. Purified alpha-toxin, heat-inactivated toxin, or alpha-toxin plus normal serum, alpha-toxin anti-serum, or the chemical inhibitor, methyl-β-cyclodextrin-cholesterol (CD-cholesterol), was injected into the rabbit anterior chamber. Pathological changes were photographed, quantified by slit-lamp examination (SLE) scoring, and further documented by histopathological analysis. At five hours post-injection, eyes injected with alpha-toxin or heat-inactivated toxin had a mean SLE score of 7.3 ± 0.59 or 0.84 ± 0.19, respectively. Active toxin caused moderate to severe iris edema, severe erosion of the iris, and mild to moderate fibrin accumulation in the anterior chamber. Alpha-toxin plus anti-serum or CD-cholesterol, in contrast to alpha-toxin alone, caused less iris edema and epithelium sloughing as well as significantly lower SLE scores than eyes receiving alpha-toxin alone (p ≤ 0.019). Alpha-toxin caused extensive iris damage and inflammation, and either anti-alpha-toxin anti-serum or CD-cholesterol was able to significantly reduce toxin-mediated damage and inflammation.

Parasympathetic, sympathetic, and sensory interactions in the iris: nerve growth factor regulates cholinergic ciliary ganglion innervation in vivo.

PubMed

Kessler, J A

1985-10-01

Interactions between peptidergic sensory nerves, noradrenergic sympathetic nerves, and cholinergic parasympathetic fibers were examined in the rat iris. The putative peptide neurotransmitter, substance P (SP), was used as an index of the trigeminal sensory innervation, tyrosine hydroxylase (TH) activity served to monitor the sympathetic fibers, and choline acetyltransferase (CAT) activity was used as an index of the parasympathetic innervation. Destruction of the sympathetic innervation by neonatal administration of 6-hydroxydopamine resulted in increased SP development and a smaller increase in CAT activity in the iris. Moreover, trigeminal ablation resulted in an increase in both TH and CAT activities. Finally, ciliary ganglionectomy resulted in increased SP and a smaller increase in TH activity in the iris. Administration of nerve growth factor (NGF) into the anterior chamber substantially increased both SP and TH activity in the iris and also increased CAT activity to a lesser extent. Moreover, administration of anti-NGF into the anterior chamber prevented both the sympathectomy-induced increases in SP and CAT, and the increases in TH and CAT activities after trigeminal ablation, suggesting that NGF mediated these increases. These observations suggest that the sympathetic, sensory, and parasympathetic innervations of the iris interact by altering availability of NGF elaborated by the iris. Regulation of iris CAT activity was examined in greater detail. Injection of the cholinergic toxin, AF64A, into the anterior chamber concurrently with ablation of the sympathetic and sensory innervations paradoxically increased CAT activity, whereas AF64A alone decreased CAT activity.(ABSTRACT TRUNCATED AT 250 WORDS)

3D evaluation of maxillary arches in unilateral cleft lip and palate patients treated with nasoalveolar moulding vs. Hotz's plate.

PubMed

Cerón-Zapata, A M; López-Palacio, A M; Rodriguez-Ardila, M J; Berrio-Gutiérrez, L M; De Menezes, M; Sforza, C

2016-02-01

To compare the three-dimensional changes occurring in the maxillary arch during the use of modified pre-surgical nasoalveolar moulding (PNAM) and Hotz's plate. A clinical trial including 32 children with unilateral cleft lip and palate (UCLP), 16 treated with Hotz's plate and 16 with PNAM, was performed. Impressions of the maxillary arches were taken: A. prior to pre-surgical orthopaedics, B. before cheiloplasty and C. after cheiloplasty. Models were digitised using a stereophotogrammetric instrument, and geodesic distances were calculated: anterior, canine and posterior widths of the arch, and lengths and cleft depths of the larger and shorter segments. The time and treatment effects were assessed by two-factor anova. A significant effect of treatment was found for cleft depth at the larger segment: children treated with Hotz's plate had significantly deeper cleft than children treated with PNAM. All distances significantly changed during time: the anterior and canine widths decreased, while the posterior width, the lengths and depths of the cleft segments increased. Significant treatment per time interactions was found. The anterior and canine widths reduced more with PNAM between time points A and B while Hotz's treatment was more effective between B and C. The shorter segment depth increased more between B and C with PNAM, and between A and B with Hotz's plate. During pre-surgical orthopaedics, therapy with PNAM obtained the best results in reducing the width at the anterior segment of the cleft. This treatment gave a lower increase in cleft depth than treatment with Hotz's plate. © 2015 John Wiley & Sons Ltd.

Three-dimensional anterior segment imaging in patients with type 1 Boston Keratoprosthesis with switchable full depth range swept source optical coherence tomography

PubMed Central

Poddar, Raju; Cortés, Dennis E.; Werner, John S.; Mannis, Mark J.

2013-01-01

Abstract. A high-speed (100 kHz A-scans/s) complex conjugate resolved 1 μm swept source optical coherence tomography (SS-OCT) system using coherence revival of the light source is suitable for dense three-dimensional (3-D) imaging of the anterior segment. The short acquisition time helps to minimize the influence of motion artifacts. The extended depth range of the SS-OCT system allows topographic analysis of clinically relevant images of the entire depth of the anterior segment of the eye. Patients with the type 1 Boston Keratoprosthesis (KPro) require evaluation of the full anterior segment depth. Current commercially available OCT systems are not suitable for this application due to limited acquisition speed, resolution, and axial imaging range. Moreover, most commonly used research grade and some clinical OCT systems implement a commercially available SS (Axsun) that offers only 3.7 mm imaging range (in air) in its standard configuration. We describe implementation of a common swept laser with built-in k-clock to allow phase stable imaging in both low range and high range, 3.7 and 11.5 mm in air, respectively, without the need to build an external MZI k-clock. As a result, 3-D morphology of the KPro position with respect to the surrounding tissue could be investigated in vivo both at high resolution and with large depth range to achieve noninvasive and precise evaluation of success of the surgical procedure. PMID:23912759

Echocardiographic characteristics of the criss-cross heart.

PubMed

Yang, Ya-Li; Wang, Xin-Fang; Cheng, Tsung O; Xie, Ming-Xing; Lü, Qing; He, Lin; Lu, Xiao-Fang; Wang, Jing; Li, Ling; Anderson, Robert H

2010-04-15

To assess the ultrasonic characteristics of the criss-cross heart, and explore the value of echocardiography in the diagnosis of this rare congenital cardiac defect. We reviewed the echocardiographic findings in 4 patients having criss-crossed atrioventricular connections at our hospital, and compared the findings with observations at surgery in 3 of the patients. In all 4 patients, there was usual atrial arrangement, right hand ventricular topology, and concordant atrioventricular connections. The inlet components of the ventricular mass, however, crossed such that the apical component of the morphologically right ventricle was situated anteriorly and superiorly, and extended to the left relative to the apex of the morphologically left ventricle. The ventriculo-arterial connections were concordant in 1 patient, double outlet from the morphologically right ventricle in 2, and discordant in the other. In all 4 patients, it proved impossible to obtain the standard 4-chamber view showing simultaneously all four chambers and both atrioventricular valves. A series of apical 4-chamber or subcostal coronal views, obtained by tilting the transducer from posterior to anterior, demonstrate initially the connection of the left-sided left atrium and the right-sided left ventricle through the mitral valve. More anterior angulation of the transducer then showed the right-sided right atrium to be connected to the left-sided right ventricle through the tricuspid valve, confirming the presence of twisted atrioventricular connections. Color Doppler imaging displayed the crossing of the atrioventricular connections without mixing of the streams. Short-axis views across the ventricular mass confirmed that the right ventricle was superior, anterior, and to the left of the left ventricle, and demonstrated the horizontal position of the ventricular septum. When viewed subcostally, the distance between the tricuspid valve and the orifice of the inferior vena cava was significantly increased relative to normal findings. The echocardiographic findings were confirmed during surgical interventions in 3 patients, apart from the failure to diagnose one instance of persistent patency of the left superior vena cava. The failure to obtain a characteristic 4-chamber view in any cut was diagnostic for recognition of the criss-crossed atrioventricular junctions. Transthoracic echocardiography provides definitive images of this rare arrangement, and accurately defines the associated cardiac abnormalities. Copyright 2009. Published by Elsevier Ireland Ltd.

Topographical investigation of changes in depth-wise proteoglycan distribution in rabbit femoral articular cartilage at 4 weeks after transection of the anterior cruciate ligament.

PubMed

Arokoski, Mikko E A; Tiitu, Virpi; Jurvelin, Jukka S; Korhonen, Rami K; Fick, James M

2015-09-01

In this study, we explore topographical changes in proteoglycan distribution from femoral condylar cartilage in early osteoarthritis, acquired from both the lateral and medial condyles of anterior cruciate ligament transected (ACLT) and contralateral (CNTRL) rabbit knee joints, at 4 weeks post operation. Four sites across the cartilage surface in a parasagittal plane were defined across tissue sections taken from femoral condyles, and proteoglycan (PG) content was quantified using digital densitometry. The greatest depth-wise change in PG content due to an ACLT (compared to the CNTRL group) was observed anteriorly (site C) from the most weight-bearing location within the lateral compartment. In the medial compartment, the greatest change was observed in the most weight-bearing location (site B). The depth-wise changes in PG content were observed up to 48% and 28% depth from the tissue surface at these aforementioned sites, respectively (p < 0.05). The smallest depth-wise change in PG content was observed posteriorly (site A) from the most weight-bearing location within both femoral condyles (up to 20% and up to 5% depth from the tissue surface at lateral and medial compartments, respectively). This study gives further insight into how early cartilage deterioration progresses across the parasagittal plane of the femoral condyle. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Anisometropia of ocular refractive and biometric measures among 66- to 79-year-old female twins.

PubMed

Pärssinen, Olavi; Kauppinen, Markku; Kaprio, Jaakko; Rantanen, Taina

2016-12-01

To examine the prevalence of anisometropia of spherical refraction (AnisoSR), astigmatism (AnisoAST) and spherical equivalent (AnisoSE) and their associations with spherical refraction (SR), refractive astigmatism (AST), spherical equivalent (SE) and interocular differences of ocular biometric parameters among elderly female twins. Refraction of 117 monozygotic (MZ) and 116 dizygotic (DZ) female twin subjects aged 66-79 years was assessed with an auto-refractor (Topcon AT) and controlled by subjective refraction. Corneal refraction, anterior chamber depth and axial length were measured with a Zeiss IOL Master. Participants with eyes operated for cataract or glaucoma were excluded, but the grade of nuclear opacity was not recorded. The associations between the absolute values of AnisoSR, AnisoAST and AnisoSE with SR, AST, SE, corneal refractive power (CR), corneal astigmatism (CAST), anterior chamber depth (ACD) and axial length (AL) and with their interocular differences were calculated. When calculating the interdependencies of the differences, the real and absolute differences between the right and left eye were used. Means ± standard deviations for AnisoSR, AnisoAST and AnisoSE were 0.67 ± 0.92 D, 0.42 ± 0.41 D and 0.65 ± 0.71 D, respectively. AnisoSR, AnisoAST and AnisoSE >1.0 D were present in 14.7%, 4.2% and 17.7% of cases, respectively. Anisometropia of spherical refraction (AnisoSR), AnisoAST and AnisoSE were higher the more negative the values of SR or SE. Hyperopic ametropia did not increase these anisometropia values. The correlations of AnisoSR and AnisoSE with the absolute values of interocular differences in CR and AL were non-significant. Using the real values of the interocular differences, the respective correlations were significant. The correlation between the real interocular differences in CR and AL was negative (r = -0.258, p < 0.001). Thus, the combined effect of the real interocular differences in CR and AL was a decrease in AnisoSR and AnisoSE (emmetropization). Higher AnisoSR and AnisoSE were associated with more myopic refraction and longer AL. Higher AnisoAST was associated with more negative SR and higher AST and CAST. The negative correlation between real interocular differences in CR and AL indicated their influence of emmetropization in AnisoSR and AnisoSE. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

SU‐C‐105‐05: Reference Dosimetry of High‐Energy Electron Beams with a Farmer‐Type Ionization Chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muir, B; Rogers, D

2013-06-15

Purpose: To investigate gradient effects and provide Monte Carlo calculated beam quality conversion factors to characterize the Farmer‐type NE2571 ion chamber for high‐energy reference dosimetry of clinical electron beams. Methods: The EGSnrc code system is used to calculate the absorbed dose to water and to the gas in a fully modeled NE2571 chamber as a function of depth in a water phantom. Electron beams incident on the surface of the phantom are modeled using realistic BEAMnrc accelerator simulations and electron beam spectra. Beam quality conversion factors are determined using calculated doses to water and to air in the chamber inmore » high‐energy electron beams and in a cobalt‐60 reference field. Calculated water‐to‐air stopping power ratios are employed for investigation of the overall ion chamber perturbation factor. Results: An upstream shift of 0.3–0.4 multiplied by the chamber radius, r-cav, both minimizes the variation of the overall ion chamber perturbation factor with depth and reduces the difference between the beam quality specifier (R{sub 5} {sub 0}) calculated using ion chamber simulations and that obtained with simulations of dose‐to‐water in the phantom. Beam quality conversion factors are obtained at the reference depth and gradient effects are optimized using a shift of 0.2r-cav. The photon‐electron conversion factor, k-ecal, amounts to 0.906 when gradient effects are minimized using the shift established here and 0.903 if no shift of the data is used. Systematic uncertainties in beam quality conversion factors are investigated and amount to between 0.4 to 1.1% depending on assumptions used. Conclusion: The calculations obtained in this work characterize the use of an NE2571 ion chamber for reference dosimetry of high‐energy electron beams. These results will be useful as the AAPM continues to review their reference dosimetry protocols.« less

Fibrinous iritis due to oxybuprocaine.

PubMed

Haddad, R

1989-01-01

Following minor surgery performed under topical application of oxybuprocaine (Dorsacaine, Novesin) two patients suffered from fibrinous iritis and moderate corneal swelling. We believe that this represents a toxic reaction caused by an inadvertent entry of this drug into the anterior chamber during the procedure.

Pseudophakodonesis and corneal endothelial contact: direct observations by high-speed cinematography.

PubMed

Jacobs, P M; Cheng, H; Price, N C

1983-10-01

High-speed cinematography was used to observe the movement of Federov type I lens implants within the anterior chamber. Our measurements suggest that in most patients contact between the lens implant and corneal endothelium does not occur.

Silicon microfabricated beam expander

NASA Astrophysics Data System (ADS)

Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

2015-03-01

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

Efficacy and safety of an extemporaneous preparation of 2% ganciclovir eye drops in CMV anterior uveitis

PubMed Central

Keorochana, Narumon; Choontanom, Raveewan

2017-01-01

Background To evaluate the efficacy and safety of an extemporaneous preparation of 2% ganciclovir topical eye drops in cytomegalovirus (CMV) anterior uveitis because many studies have confirmed the benefits of topical ganciclovir in varying concentrations. Design The study employed a retrospective cohort design. Methods This study enrolled 11 eyes (11 patients) with CMV anterior uveitis. All cases were proved by positive PCR for CMV DNA from aqueous tapping and received topical 2% ganciclovir, applied every 2 hours daily as induction therapy then tapered off and stopped based on clinical response. Outcome measures were best-corrected visual acuity, anterior chamber cell, coin-shaped and other keratic precipitates, intraocular pressure (IOP), the number of antiglaucoma drugs used, the frequency of steroid eye drops used daily and side effects over a 12-month follow-up period. Side effects after applying topical 2% ganciclovir were recorded using questionnaires and eye examination. Results Mean age was 49.0±17.8 years. IOP, number of antiglaucoma drugs used and keratic precipitates decreased significantly at first week (p<0.013, p<0.024 and p<0.031, respectively) followed by decreased anterior chamber cells and significantly reduced frequency of applying steroid eye drops at 4 weeks (p<0.034 and p<0.017, respectively). Visual acuity significantly improved at 5 months continuously. All clinical improvement was maintained to 12 months, and keratic precipitates were eliminated in 90% of all cases. However, in 27% of discontinued medicine cases, inflammation was recurrent. No significance was observed in all factors between recurrent and non-recurrent groups. The most common side effect was eye irritation (27.27%). No severe complications from the medicine was detected. Conclusion Extemporaneous preparation topical 2% ganciclovir was effective and safely controlled CMV anterior uveitis. The medication is non-invasive, economical and convenient for hospitals where commercial topical ganciclovir is unavailable. PMID:29354718

Efficacy and safety of an extemporaneous preparation of 2% ganciclovir eye drops in CMV anterior uveitis.

PubMed

Keorochana, Narumon; Choontanom, Raveewan

2017-01-01

To evaluate the efficacy and safety of an extemporaneous preparation of 2% ganciclovir topical eye drops in cytomegalovirus (CMV) anterior uveitis because many studies have confirmed the benefits of topical ganciclovir in varying concentrations. The study employed a retrospective cohort design. This study enrolled 11 eyes (11 patients) with CMV anterior uveitis. All cases were proved by positive PCR for CMV DNA from aqueous tapping and received topical 2% ganciclovir, applied every 2 hours daily as induction therapy then tapered off and stopped based on clinical response. Outcome measures were best-corrected visual acuity, anterior chamber cell, coin-shaped and other keratic precipitates, intraocular pressure (IOP), the number of antiglaucoma drugs used, the frequency of steroid eye drops used daily and side effects over a 12-month follow-up period. Side effects after applying topical 2% ganciclovir were recorded using questionnaires and eye examination. Mean age was 49.0±17.8 years. IOP, number of antiglaucoma drugs used and keratic precipitates decreased significantly at first week (p<0.013, p<0.024 and p<0.031, respectively) followed by decreased anterior chamber cells and significantly reduced frequency of applying steroid eye drops at 4 weeks (p<0.034 and p<0.017, respectively). Visual acuity significantly improved at 5 months continuously. All clinical improvement was maintained to 12 months, and keratic precipitates were eliminated in 90% of all cases. However, in 27% of discontinued medicine cases, inflammation was recurrent. No significance was observed in all factors between recurrent and non-recurrent groups. The most common side effect was eye irritation (27.27%). No severe complications from the medicine was detected. Extemporaneous preparation topical 2% ganciclovir was effective and safely controlled CMV anterior uveitis. The medication is non-invasive, economical and convenient for hospitals where commercial topical ganciclovir is unavailable.

SU-E-T-82: A Study On Enhanced Dynamic Wedge (EDW) Dosimetry Using 2D Seven29 Ion Chamber Array Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Syam; Aparna

2015-06-15

Purpose: To study the dosimetric properties of Enhanced Dynamic Wedge (EDW) using PTW Seven29 ion chamber array Methods: PTW Seven29 ion chamber array and Solid Water phantoms for different depths were used for the study. The study was carried out in Varian Clinac ix with photon energies, 6MV & 15MV. Primarily the solid water phantoms with the 2D array were scanned using a CT scanner (GE Optima 580) at different depths. These scanned images were used for EDW planning in an Eclipse treatment planning system (version 10). Planning was done for different wedge angles and for different depths for 6MVmore » & 15MV. A dose of 100 CGy was delivered in each cases. For each delivery, calculated the Monitoring Unit (MU) required. Same set-up was created before delivering the plans in Varian Clinac-ix. For each clinically relevant depth and for different wedge angles, the same MU was delivered as calculated. Different wedged dose distributions where reconstructed from the measured 2D array data using the in-house developed excel program. Results: It is observed that the shoulder like region in the profile which reduces as depth increases. For the same depth and energy, the percentage difference between planned and measured dose is lesser than 3%. For smaller wedge angles, the percentage difference is found to be greater than 3% for the largest wedge angle. Standard deviation between measured doses at shoulder region for planned and measured profiles is 0.08 and 0.02 respectively. Standard deviations between planned and measured wedge factors for different depths (2.5cm, 5cm, 10cm, and 15cm) are (0.0021, 0.0007, 0.0050, 0.0001) for 6MV and (0.0024, 0.0191, 0.0013, 0.0005) for 15MV respectively. Conclusion: The 2D Seven29 ion chamber array is a good tool for the Enhanced Dynamic Wedge (EDW) dosimetry.« less

An experimental study of recombination and polarity effect in a set of customized plane parallel ionization chambers.

PubMed

Kron, T; McNiven, A; Witruk, B; Kenny, M; Battista, J

2006-12-01

Plane parallel ionization chambers are an important tool for dosimetry and absolute calibration of electron beams used for radiotherapy. Most dosimetric protocols require corrections for recombination and polarity effects, which are to be determined experimentally as they depend on chamber design and radiation quality. Both effects were investigated in electron beams from a linear accelerator (Varian 21CD) for a set of four tissue equivalent plane parallel ionization chambers customized for the present research by Standard Imaging (Madison WI). All four chambers share the same design and air cavity dimensions, differing only in the diameter of their collecting electrode and the corresponding width of the guard ring. The diameters of the collecting electrodes were 2 mm, 4 mm, 10 mm and 20 mm. Measurements were taken using electron beams of nominal energy 6 to 20 MeV in a 10 cm x 10 cm field size with a SSD of 100 cm at various depths in a Solid Water slab phantom. No significant variation of recombination effect was found with radiation quality, depth of measurement or chamber design. However, the polarity effect exceeded 5% for the chambers with small collecting electrode for an effective electron energy below 4 MeV at the point of measurement. The magnitude of the effect increased with decreasing electron energy in the phantom. The polarity correction factor calculated following AAPM protocol TG51 ranged from approximately 1.00 for the 20.0 mm chamber to less than 0.95 for the 2 mm chamber at 4.1 cm depth in a electron beam of nominally 12 MeV. By inverting the chamber it could be shown that the polarity effect did not depend on the polarity of the electrode first traversed by the electron beam. Similarly, the introduction of an air gap between the overlying phantom layer and the chambers demonstrated that the angular distribution of the electrons at the point of measurement had a lesser effect on the polarity correction than the electron energy itself. The magnitude of the absolute difference between charge collected at positive and negative polarity was found to correlate with the area of the collecting electrode which is consistent with the explanation that differences in thickness of the collecting electrodes and the number of electrons stopped in them contribute significantly to the polarity effect. Overall, the polarity effects found in the present study would have a negligible effect on electron beam calibration at a measurement depth recommended by most calibration protocols. However, the present work tested the corrections under extreme conditions thereby aiming at greater understanding of the mechanism underlying the correction factors for these chambers. This may lead to better chamber design for absolute dosimetry and electron beam characterization with less reliance on empirical corrections.

Evaluation of Parallel-Element, Variable-Impedance, Broadband Acoustic Liner Concepts

NASA Technical Reports Server (NTRS)

Jones, Michael G.; Howerton, Brian M.; Ayle, Earl

2012-01-01

Recent trends in aircraft engine design have highlighted the need for acoustic liners that provide broadband sound absorption with reduced liner thickness. Three such liner concepts are evaluated using the NASA normal incidence tube. Two concepts employ additive manufacturing techniques to fabricate liners with variable chamber depths. The first relies on scrubbing losses within narrow chambers to provide acoustic resistance necessary for sound absorption. The second employs wide chambers that provide minimal resistance, and relies on a perforated sheet to provide acoustic resistance. The variable-depth chambers used in both concepts result in reactance spectra near zero. The third liner concept employs mesh-caps (resistive sheets) embedded at variable depths within adjacent honeycomb chambers to achieve a desired impedance spectrum. Each of these liner concepts is suitable for use as a broadband sound absorber design, and a transmission line model is presented that provides good comparison with their respective acoustic impedance spectra. This model can therefore be used to design acoustic liners to accurately achieve selected impedance spectra. Finally, the effects of increasing the perforated facesheet thickness are demonstrated, and the validity of prediction models based on lumped element and wave propagation approaches is investigated. The lumped element model compares favorably with measured results for liners with thin facesheets, but the wave propagation model provides good comparisons for a wide range of facesheet thicknesses.

Pseudophakodonesis and corneal endothelial contact: direct observations by high-speed cinematography.

PubMed Central

Jacobs, P M; Cheng, H; Price, N C

1983-01-01

High-speed cinematography was used to observe the movement of Federov type I lens implants within the anterior chamber. Our measurements suggest that in most patients contact between the lens implant and corneal endothelium does not occur. Images PMID:6615750

Femtosecond laser-assisted cataract surgery in Alport syndrome with anterior lenticonus.

PubMed

Ecsedy, Mónika; Súndor, Gúbor L; Takúcs, Úgnes I; Krúnitz, Kinga; Kiss, Zoltún; Kolev, Krasimir; Nagy, Zoltún Z

2015-01-01

To report the surgical treatment of 3 eyes of 2 patients with bilateral anterior lenticonus due to Alport syndrome using femtosecond laser-assisted cataract surgery (FLACS). Two patients with Alport syndrome presented to our department due to anterior lenticonus in both eyes. We performed FLACS with posterior chamber lens implantation in both eyes of one patient and in one eye of the other patient. Anterior segment morphologic changes were visualized with a Scheimpflug camera, and anterior segment optical coherence tomography preoperatively and 3 months after surgery. Ultrastructure of the cut capsule edges was observed with scanning electron microscopy and compared to the edge of femtosecond laser capsulotomy performed on an otherwise healthy patient with cataract (control). The intraocular lens (IOL) postoperative positioning parameters met the international requirements of aspherical and wavefront customized IOLs (tilt <10 degree, decentration <800 µm). Scanning electron microscopy revealed the same characteristics of the cut capsule edges in the Alport and in the control eyes. Femtosecond laser cataract surgery can be a safe and successful method for optical rehabilitation of anterior lenticonus in patients with Alport syndrome.

Pressure atomizer having multiple orifices and turbulent generation feature

DOEpatents

VanBrocklin, Paul G.; Geiger, Gail E.; Moran, Donald James; Fournier, Stephane

2002-01-01

A pressure atomizer includes a silicon plate having a top surface and a bottom surface. A portion of the top surface defines a turbulent chamber. The turbulent chamber is peripherally bounded by the top surface of the plate. The turbulent chamber is recessed a predetermined depth relative to the top surface. The silicon plate further defines at least one flow orifice. Each flow orifice extends from the bottom surface of the silicon plate to intersect with and open into the turbulent chamber. Each flow orifice is in fluid communication with the turbulent chamber.

Monte Carlo calculations of electron beam quality conversion factors for several ion chamber types.

PubMed

Muir, B R; Rogers, D W O

2014-11-01

To provide a comprehensive investigation of electron beam reference dosimetry using Monte Carlo simulations of the response of 10 plane-parallel and 18 cylindrical ion chamber types. Specific emphasis is placed on the determination of the optimal shift of the chambers' effective point of measurement (EPOM) and beam quality conversion factors. The EGSnrc system is used for calculations of the absorbed dose to gas in ion chamber models and the absorbed dose to water as a function of depth in a water phantom on which cobalt-60 and several electron beam source models are incident. The optimal EPOM shifts of the ion chambers are determined by comparing calculations of R50 converted from I50 (calculated using ion chamber simulations in phantom) to R50 calculated using simulations of the absorbed dose to water vs depth in water. Beam quality conversion factors are determined as the calculated ratio of the absorbed dose to water to the absorbed dose to air in the ion chamber at the reference depth in a cobalt-60 beam to that in electron beams. For most plane-parallel chambers, the optimal EPOM shift is inside of the active cavity but different from the shift determined with water-equivalent scaling of the front window of the chamber. These optimal shifts for plane-parallel chambers also reduce the scatter of beam quality conversion factors, kQ, as a function of R50. The optimal shift of cylindrical chambers is found to be less than the 0.5 rcav recommended by current dosimetry protocols. In most cases, the values of the optimal shift are close to 0.3 rcav. Values of kecal are calculated and compared to those from the TG-51 protocol and differences are explained using accurate individual correction factors for a subset of ion chambers investigated. High-precision fits to beam quality conversion factors normalized to unity in a beam with R50 = 7.5 cm (kQ (')) are provided. These factors avoid the use of gradient correction factors as used in the TG-51 protocol although a chamber dependent optimal shift in the EPOM is required when using plane-parallel chambers while no shift is needed with cylindrical chambers. The sensitivity of these results to parameters used to model the ion chambers is discussed and the uncertainty related to the practical use of these results is evaluated. These results will prove useful as electron beam reference dosimetry protocols are being updated. The analysis of this work indicates that cylindrical ion chambers may be appropriate for use in low-energy electron beams but measurements are required to characterize their use in these beams.

Ophthalmic diagnostic tests in captive red-footed tortoises (Chelonoidis carbonaria) in Salvador, northeast Brazil.

PubMed

Oriá, Arianne P; Silva, Renata M Monção; Pinna, Melissa H; Oliveira, Alberto Vinícius D; Ferreira, Paulo Roberto B; Martins Filho, Emanoel F; Meneses, Iris Daniela S; Requião, Kátia G; Ofri, Ron

2015-01-01

The aim of this study was to establish normal ophthalmic parameters for select diagnostic tests in red-footed tortoises (Chelonoides carbonaria). A total of 52 animals, approximately 20-30 years old, were studied. Ophthalmic diagnostic tests included culturing of the normal conjunctival bacterial flora in summer and winter, evaluation of tear production using Schirmer tear test (STT) and endodontic absorbent paper point tear test in two different environmental temperatures (EAPPTT-1 at 32 °C and EAPPTT-2 at 18 °C), cytology of conjunctival cells, B-mode ultrasonography, measurement of palpebral fissure length (PFL), and applanation tonometry (in two different positions). In both seasons, Gram-positive bacteria were predominant. Median (± IQR/2) STT was 12.0 ± 3.5 mm/min, EAPPTT-1 was 15.9 ± 0.7 mm/15 s, and EAPPTT-2 was 15.4 ± 0.4 mm/min (OD) and 17.8 ± 1.0 mm/min (OS). Anterior chamber depth was 1.0 ± 0.1 mm, lens axial length was 2.3 ± 0.1 mm, vitreous chamber depth was 4.3 ± 0.2 mm, and axial globe length was 7.7 ± 0.3 mm. PFL was 11.7 ± 1.7 mm. Intraocular pressure was 11.5 ± 2.8 mmHg for males and 14.0 ± 3.5 mmHg for females (dorsoventral position) and 18.0 ± 3.2 mmHg for males and 24.1 ± 3.0 mmHg for females (ventrodorsal position with inclination of 45°). The ophthalmic parameters reported here can aid in the diagnosis of eye diseases in red-footed tortoises (Chelonoides carbonaria). © 2014 American College of Veterinary Ophthalmologists.

Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

NASA Astrophysics Data System (ADS)

Watson, Peter G. F.; Popovic, Marija; Seuntjens, Jan

2018-01-01

Electronic brachytherapy sources are widely accepted as alternatives to radionuclide-based systems. Yet, formal dosimetry standards for these devices to independently complement the dose protocol provided by the manufacturer are lacking. This article presents a formalism for calculating and independently verifying the absorbed dose to water from a kV x-ray source (The INTRABEAM System) measured in a water phantom with an ionization chamber calibrated in terms of air-kerma. This formalism uses a Monte Carlo (MC) calculated chamber conversion factor, CQ , to convert air-kerma in a reference beam to absorbed dose to water in the measurement beam. In this work CQ was determined for a PTW 34013 parallel-plate ionization chamber. Our results show that CQ was sensitive to the chamber plate separation tolerance, with differences of up to 15%. CQ was also found to have a depth dependence which varied with chamber plate separation (0 to 10% variation for the smallest and largest cavity height, over 3 to 30 mm depth). However for all chamber dimensions investigated, CQ was found to be significantly larger than the manufacturer reported value, suggesting that the manufacturer recommended method of dose calculation could be underestimating the dose to water.

A Magnetic Microbead Occlusion Model to Induce Ocular Hypertension-Dependent Glaucoma in Mice

PubMed Central

Cueva Vargas, Jorge L.; Di Polo, Adriana

2016-01-01

The use of rodent models of glaucoma has been essential to understand the molecular mechanisms that underlie the pathophysiology of this multifactorial neurodegenerative disease. With the advent of numerous transgenic mouse lines, there is increasing interest in inducible murine models of ocular hypertension. Here, we present an occlusion model of glaucoma based on the injection of magnetic microbeads into the anterior chamber of the eye using a modified microneedle with a facetted bevel. The magnetic microbeads are attracted to the iridocorneal angle using a handheld magnet to block the drainage of aqueous humour from the anterior chamber. This disruption in aqueous dynamics results in a steady elevation of intraocular pressure, which subsequently leads to the loss of retinal ganglion cells, as observed in human glaucoma patients. The microbead occlusion model presented in this manuscript is simple compared to other inducible models of glaucoma and also highly effective and reproducible. Importantly, the modifications presented here minimize common issues that often arise in occlusion models. First, the use of a bevelled glass microneedle prevents backflow of microbeads and ensures that minimal damage occurs to the cornea during the injection, thus reducing injury-related effects. Second, the use of magnetic microbeads ensures the ability to attract most beads to the iridocorneal angle, effectively reducing the number of beads floating in the anterior chamber avoiding contact with other structures (e.g., iris, lens). Lastly, the use of a handheld magnet allows flexibility when handling the small mouse eye to efficiently direct the magnetic microbeads and ensure that there is little reflux of the microbeads from the eye when the microneedle is withdrawn. In summary, the microbead occlusion mouse model presented here is a powerful investigative tool to study neurodegenerative changes that occur during the onset and progression of glaucoma. PMID:27077732

Clinical outcomes of Ahmed glaucoma valve in anterior chamber versus ciliary sulcus.

PubMed

Bayer, A; Önol, M

2017-04-01

PurposeTo evaluate the outcomes of Ahmed glaucoma valve (AGV) tube insertion through the anterior chamber angle (ACA) or through the ciliary sulcus (CS).Patients and methodsIn this case-control study, we retrospectively reviewed the charts of consecutive glaucoma patients who had undergone AGV implantation either through the ACA or the CS between March 2009 and December 2014. The main outcome measures were intraocular pressure (IOP), number of glaucoma medications prescribed, best corrected visual acuity (BCVA), glaucoma type, success rate, complications, and survival ratios. Statistical analysis was carried out using SPSS.ResultsThere were 68 eyes in the ACA group and 35 eyes in the CS group. There were no significant differences between the groups for age, sex, laterality, IOP, preoperative glaucoma medication number, BCVA or glaucoma type (P>0.05). The postoperative follow-up period was 27.2±16.5 months and 30.2±17.7 months for the ACA and the CS groups (P=0.28); IOP values were significantly reduced at the last visit to 16.4±7.2 mm Hg and 14.4±6.8 mm Hg. The difference in the last-visit IOP between the groups was not significant (P=0.06), but the IOP reduction ratio was higher in the CS group (P=0.03). There was no significant difference in the number of postoperative medications (P=0.18). Postoperative complications were similar, but the incidence of flat anterior chamber was higher in the ACA group (P=0.05).ConclusionsThe use of an AGV can control IOP in the majority of cases whether placed in the ACA or the CS. The IOP reduction ratio seemed to be higher in the CS group.

Clinical outcomes of Ahmed glaucoma valve in anterior chamber versus ciliary sulcus

PubMed Central

Bayer, A; Önol, M

2017-01-01

Purpose To evaluate the outcomes of Ahmed glaucoma valve (AGV) tube insertion through the anterior chamber angle (ACA) or through the ciliary sulcus (CS). Patients and methods In this case-control study, we retrospectively reviewed the charts of consecutive glaucoma patients who had undergone AGV implantation either through the ACA or the CS between March 2009 and December 2014. The main outcome measures were intraocular pressure (IOP), number of glaucoma medications prescribed, best corrected visual acuity (BCVA), glaucoma type, success rate, complications, and survival ratios. Statistical analysis was carried out using SPSS. Results There were 68 eyes in the ACA group and 35 eyes in the CS group. There were no significant differences between the groups for age, sex, laterality, IOP, preoperative glaucoma medication number, BCVA or glaucoma type (P>0.05). The postoperative follow-up period was 27.2±16.5 months and 30.2±17.7 months for the ACA and the CS groups (P=0.28); IOP values were significantly reduced at the last visit to 16.4±7.2 mm Hg and 14.4±6.8 mm Hg. The difference in the last-visit IOP between the groups was not significant (P=0.06), but the IOP reduction ratio was higher in the CS group (P=0.03). There was no significant difference in the number of postoperative medications (P=0.18). Postoperative complications were similar, but the incidence of flat anterior chamber was higher in the ACA group (P=0.05). Conclusions The use of an AGV can control IOP in the majority of cases whether placed in the ACA or the CS. The IOP reduction ratio seemed to be higher in the CS group. PMID:27983734

The effect of biologic therapy different from infliximab or adalimumab in patients with refractory uveitis due to Behçet's disease: results of a multicentre open-label study.

PubMed

Santos-Gómez, Montserrat; Calvo-Río, Vanesa; Blanco, Ricardo; Beltrán, Emma; Mesquida, Marina; Adán, Alfredo; Cordero-Coma, Miguel; García-Aparicio, Ángel M; Valls Pascual, Elia; Martínez-Costa, Lucía; Hernández, María Victoria; Hernandez Garfella, Marisa; González-Vela, María C; Pina, Trinitario; Palmou-Fontana, Natalia; Loricera, Javier; Hernández, José L; González-Gay, Miguel A

2016-01-01

To assess the efficacy of other biologic therapies, different from infliximab (IFX) and adalimumab (ADA), in patients with Behçet's disease uveitis (BU). Multicenter study of 124 patients with BU refractory to at least one standard immunosuppressive agent that required IFX or ADA therapy. Patients who had to be switched to another biologic agent due to inefficacy or intolerance to IFX or ADA or patient's decision were assessed. The main outcome measures were the degree of anterior and posterior chamber inflammation and macular thickness. Seven (5.6%) of 124 cases (4 women/3 men; mean age, 43 (range 28- 67) years; 12 affected eyes) were studied. Five of them had been initially treated with ADA and 2 with IFX. The other biologic agents used were golimumab (n=4), tocilizumab (n=2) and rituximab (n=1). The ocular pattern was panuveitis (n=4) or posterior uveitis (n=3). Uveitis was bilateral in 5 patients (71.4%). At baseline, anterior chamber and vitreous inflammation were present in 6 (50%) and 7 (58.3%) of the eyes. All the patients (12 eyes) had macular thickening (OCT>250μm) and 4 of them (7 eyes), cystoid macular edema (OCT>300 μm). Besides reduction anterior chamber and vitreous inflammation, we observed a reduction of OCT values, from 330.4±58.5 μm at the onset of the biological agent to 273±50 μm at month 12 (p=0.06). Six patients achieved a complete remission of uveitis. The vast majority of patients with BU refractory to standard immunosuppressive drugs are successfully controlled with ADA and/or IFX. Other biologic agents appear to be also useful.

Comparison of depth-dose distributions of proton therapeutic beams calculated by means of logical detectors and ionization chamber modeled in Monte Carlo codes

NASA Astrophysics Data System (ADS)

Pietrzak, Robert; Konefał, Adam; Sokół, Maria; Orlef, Andrzej

2016-08-01

The success of proton therapy depends strongly on the precision of treatment planning. Dose distribution in biological tissue may be obtained from Monte Carlo simulations using various scientific codes making it possible to perform very accurate calculations. However, there are many factors affecting the accuracy of modeling. One of them is a structure of objects called bins registering a dose. In this work the influence of bin structure on the dose distributions was examined. The MCNPX code calculations of Bragg curve for the 60 MeV proton beam were done in two ways: using simple logical detectors being the volumes determined in water, and using a precise model of ionization chamber used in clinical dosimetry. The results of the simulations were verified experimentally in the water phantom with Marcus ionization chamber. The average local dose difference between the measured relative doses in the water phantom and those calculated by means of the logical detectors was 1.4% at first 25 mm, whereas in the full depth range this difference was 1.6% for the maximum uncertainty in the calculations less than 2.4% and for the maximum measuring error of 1%. In case of the relative doses calculated with the use of the ionization chamber model this average difference was somewhat greater, being 2.3% at depths up to 25 mm and 2.4% in the full range of depths for the maximum uncertainty in the calculations of 3%. In the dose calculations the ionization chamber model does not offer any additional advantages over the logical detectors. The results provided by both models are similar and in good agreement with the measurements, however, the logical detector approach is a more time-effective method.

Characterization of a new commercial single crystal diamond detector for photon- and proton-beam dosimetry.

PubMed

Akino, Yuichi; Gautam, Archana; Coutinho, Len; Würfel, Jan; Das, Indra J

2015-11-01

A synthetic single crystal diamond detector (SCDD) is commercially available and is characterized for radiation dosimetry in various radiation beams in this study. The characteristics of the commercial SCDD model 60019 (PTW) with 6- and 15-MV photon beams, and 208-MeV proton beams, were investigated and compared with the pre-characterized detectors: Semiflex (model 31010) and PinPoint (model 31006) ionization chambers (PTW), the EDGE diode detector (Sun Nuclear Corp) and the SFD Stereotactic Dosimetry Diode Detector (IBA). To evaluate the effects of the pre-irradiation, the diamond detector, which had not been irradiated on the day, was set up in the water tank, and the response to 100 MU was measured every 20 s. The depth-dose and profiles data were collected for various field sizes and depths. For all radiation types and field sizes, the depth-dose data of the diamond chamber showed identical curves to those of the ionization chambers. The profile of the diamond detector was very similar to those of the EDGE and SFD detectors, although the Semiflex and PinPoint chambers showed volume-averaging effects in the penumbrae region. The temperature dependency was within 0.7% in the range of 4-41°C. A dose of 900 cGy and 1200 cGy was needed to stabilize the chamber to the level within 0.5% and 0.2%, respectively. The PTW type 60019 SCDD detector showed suitable characteristics for radiation dosimetry, for relative dose, depth-dose and profile measurements for a wide range of field sizes. However, at least 1000 cGy of pre-irradiation will be needed for accurate measurements. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Iridoplasty of fixed-dilated pupil (Urrets-Zavalia syndrome) after deep anterior lamellar keratoplasty

PubMed Central

Ntora, Efthalia; Ziakas, Nikolaos

2017-01-01

A 38-year-old woman with advanced keratoconus initially developed Urrets-Zavalia Syndrome (UZS) in the left eye after deep anterior lamellar keratoplasty. During the uneventful surgery, a 7-mm-wide pupil unresponsive to light was noticed. On the first postoperative day, intraocular pressure (IOP) was elevated up to 45 mmHg with shallow anterior chamber (AC). A peripheral iridotomy in 2 o’clock position was conducted and a fixed combination of brinzolamide 1% and timolol 0.5% was administered topically. In the subsequent postoperative period, IOP was successfully reduced, but the patient reported severe photophobia, glare, and decreased vision. Twelve months after surgery, her best-corrected visual acuity (BCVA) was 20/200, the fixed-dilated pupil persisted, iris was atrophic, and lens opacities were detected. She was submitted for phacoemulsification cataract surgery combined with iridoplasty using the closed chamber slipping suture technique. Three months after surgery, her BCVA was 20/25, pupil diameter remained stable at 4 mm, and glare symptoms were significantly reduced. A very adequate cosmetic outcome was also achieved. Iridoplasty in postkeratoplasty patient with unilateral UZS was effective in improving patient's visual function disability and restoring residual anisocoria. This technique can be applied as a single procedure or combined with another one for the management of UZS. PMID:29118500

Primary iris stromal cyst with rapid growth.

PubMed

Xiao, Yang; Wang, Yu-Hong; Niu, Gai-Ling; Gao, Min

2009-11-01

To describe the clinical features and the surgical management of primary iris stromal cyst with rapid growth. A 14-year-old Chinese-Mongolian girl was referred to us with a 1-month history of obstructed vision and photophobia. On an examination, a semitransparent cyst with a densely pigmented posterior wall was revealed in the anterior chamber of the left eye. The information regarding the location and extent of the cyst was further analyzed by anterior segment optical coherence tomography and ultrasound biomicroscopy. It arose within the iris stroma, measuring 7.52 x 3.60 mm. Blood vessels on the surface of the lesion were revealed by iris angiography. There was no history of amniocentesis, birth trauma, antecedent ocular injury, or maternal illness during gestation. The diagnosis of primary iris stromal cyst was made. A combination of needle aspiration, piecemeal resection of cyst wall, cryotherapy, and argon laser photocoagulation with overlapped spots was used. Histopathology of the cyst wall revealed nonkeratinized, multilayered, stratified squamous epithelium with clusters of goblet cells. Complete resolution of the cyst was successfully achieved. The visual acuity improved to 20/25 from counting fingers. At 6 months of follow-up, there was no recurrence. Complete eradication and devitalization of any remaining epithelial cells are the key factors for preventing recurrence and diffuse epithelialization of the anterior chamber.

Correction factors for ionization chamber measurements with the ‘Valencia’ and ‘large field Valencia’ brachytherapy applicators

NASA Astrophysics Data System (ADS)

Gimenez-Alventosa, V.; Gimenez, V.; Ballester, F.; Vijande, J.; Andreo, P.

2018-06-01

Treatment of small skin lesions using HDR brachytherapy applicators is a widely used technique. The shielded applicators currently available in clinical practice are based on a tungsten-alloy cup that collimates the source-emitted radiation into a small region, hence protecting nearby tissues. The goal of this manuscript is to evaluate the correction factors required for dose measurements with a plane-parallel ionization chamber typically used in clinical brachytherapy for the ‘Valencia’ and ‘large field Valencia’ shielded applicators. Monte Carlo simulations have been performed using the PENELOPE-2014 system to determine the absorbed dose deposited in a water phantom and in the chamber active volume with a Type A uncertainty of the order of 0.1%. The average energies of the photon spectra arriving at the surface of the water phantom differ by approximately 10%, being 384 keV for the ‘Valencia’ and 343 keV for the ‘large field Valencia’. The ionization chamber correction factors have been obtained for both applicators using three methods, their values depending on the applicator being considered. Using a depth-independent global chamber perturbation correction factor and no shift of the effective point of measurement yields depth-dose differences of up to 1% for the ‘Valencia’ applicator. Calculations using a depth-dependent global perturbation factor, or a shift of the effective point of measurement combined with a constant partial perturbation factor, result in differences of about 0.1% for both applicators. The results emphasize the relevance of carrying out detailed Monte Carlo studies for each shielded brachytherapy applicator and ionization chamber.

Forecasting magma-chamber rupture at Santorini volcano, Greece.

PubMed

Browning, John; Drymoni, Kyriaki; Gudmundsson, Agust

2015-10-28

How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection, and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily cause an eruption but produces a net volume change that can be measured geodetically by inversion techniques. Using continuum-mechanics and fracture-mechanics principles, we calculate the amount of magma contained at shallow depth beneath Santorini volcano, Greece. We demonstrate through structural analysis of dykes exposed within the Santorini caldera, previously published data on the volume of recent eruptions, and geodetic measurements of the 2011-2012 unrest period, that the measured 0.02% increase in volume of Santorini's shallow magma chamber was associated with magmatic excess pressure increase of around 1.1 MPa. This excess pressure was high enough to bring the chamber roof close to rupture and dyke injection. For volcanoes with known typical extrusion and intrusion (dyke) volumes, the new methodology presented here makes it possible to forecast the conditions for magma-chamber failure and dyke injection at any geodetically well-monitored volcano.

Whole eye axial biometry during accommodation using ultra-long scan depth optical coherence tomography

PubMed Central

Zhong, Jianguang; Tao, Aizhu; Xu, Zhe; Jiang, Hong; Shao, Yilei; Zhang, Huicheng; Liu, Che; Wang, Jianhua

2014-01-01

PURPOSE To investigate changes of whole eye axial biometry during accommodation using ultra-long scan depth optical coherence tomography (UL-OCT). DESIGN Prospective, observational case series. METHODS Twenty-one adult subjects were enrolled. Using UL-OCT, the left eye of each subject was imaged with relaxed (0 D) and accommodative stimuli (+6 D). Full eye biometry included central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness, vitreous length and axial length (AL). RESULTS During accommodation (+6 D), the axial biometry of the whole eye changed significantly. Compared to the rest state, ACD at the accommodative state decreased significantly from 3.128 ± 0.305 mm to 2.961 ± 0.298 mm (paired t-test, P < 0.001). The lens thickness increased significantly from 3.723 ± 0.237 mm to 3.963 ± 0.234 mm (P < 0.001). The vitreous length decreased significantly from 17.129 ± 0.864 mm to 17.057± 0.848 mm (P < 0.001). AL was 24.519 ± 0.917 mm at the rest state and increased to 24.545±0.915 mm with +6 D accommodation stimulus. The elongated AL of 26.1 ± 13.4 μm between the rest and accommodative states was significant (P < 0.001). CONCLUSIONS During accommodation, whole eye axial biometry changed, including a decrease in ACD and vitreous length, and an increase in lens thickness and AL. UL-OCT provides an alternative method that is suitable for full eye biometry during accommodation. PMID:24487051

Ophthalmic variables in rehabilitated juvenile Kemp's ridley sea turtles (Lepidochelys kempii).

PubMed

Gornik, Kara R; Pirie, Christopher G; Marrion, Ruth M; Wocial, Julika N; Innis, Charles J

2016-03-15

To determine central corneal thickness (total corneal thickness [TCT], epithelial thickness [ET], and stromal thickness [ST]), anterior chamber depth (ACD), and intraocular pressure (IOP) in Kemp's ridley sea turtles (Lepidochelys kempii). Prospective cross-sectional study. 25 healthy rehabilitated juvenile Kemp's ridley sea turtles. PROCEDURES; Body weight and straight-line standard carapace length (SCL) were recorded. All turtles underwent a complete anterior segment ophthalmic examination. Central TCT, ET, ST, and ACD were determined by use of a spectral-domain optical coherence tomography device. Intraocular pressure was determined with a rebound tonometer; the horse setting was used to measure IOP in all 25 turtles, and the undefined setting was also used to measure IOP in 20 turtles. For each variable, 3 measurements were obtained bilaterally. The mean was calculated for each eye and used for analysis purposes. The mean ± SD body weight and SCL were 3.85 ± 1.05 kg (8.47 ± 2.31 lb) and 29 ± 3 cm, respectively. The mean ± SD TCT, ET, ST, and ACD were 288 ± 23 μm, 100 ± 6 μm, 190 ± 19 μm, and 581 ± 128 μm, respectively. Mean ± SD IOP was 6.5 ± 1.0 mm Hg when measured with the horse setting and 3.8 ± 1.1 mm Hg when measured with the undefined setting. Results provided preliminary reference ranges for objective assessment of ophthalmic variables in healthy juvenile Kemp's ridley sea turtles.

Comparison of anterior segment parameters and axial length measurements performed on a Scheimpflug device with biometry function and a reference optical biometer.

PubMed

Muzyka-Woźniak, Maria; Oleszko, Adam

2018-04-26

To compare measurements of axial length (AL), corneal curvature (K), anterior chamber depth (ACD) and white-to-white (WTW) distance on a new device combining Scheimpflug camera and partial coherence interferometry (Pentacam AXL) with a reference optical biometer (IOL Master 500). To evaluate differences between IOL power calculations based on the two biometers. Ninety-seven eyes of 97 consecutive cataract or refractive lens exchange patients were examined preoperatively on IOL Master 500 and Pentacam AXL units. Comparisons between two devices were performed for AL, K, ACD and WTW. Intraocular lens (IOL) power targeting emmetropia was calculated with SRK/T and Haigis formulas on both devices and compared. There were statistically significant differences between two devices for all measured parameters (P < 0.05), except ACD (P = 0.36). Corneal curvature measured with Pentacam AXL was significantly flatter then with IOL Master. The mean difference in AL was clinically insignificant (0.01 mm; 95% LoA 0.16 mm). Pentacam AXL yielded higher IOL power in 75% of eyes for Haigis formula and in 62% of eyes for SRK/T formula, with a mean difference within ± 0.5 D for 72 and 86% of eyes, respectively. There were statistically significant differences between AL, K and WTW measurements obtained with the compared biometers. Flatter corneal curvature measurements on Pentacam AXL necessitate formulas optimisation for Pentacam AXL.

The relationship between refractive and biometric changes during Edinger–Westphal stimulated accommodation in rhesus monkeys

PubMed Central

Vilupuru, Abhiram S.; Glasser, Adrian

2010-01-01

Experiments were undertaken to understand the relationship between dynamic accommodative refractive and biometric (lens thickness (LT), anterior chamber depth (ACD) and anterior segment length (ASL=ACD+LT)) changes during Edinger–Westphal stimulated accommodation in rhesus monkeys. Experiments were conducted on three rhesus monkeys (aged 11·5, 4·75 and 4·75 years) which had undergone prior, bilateral, complete iridectomies and implantation of a stimulating electrode in the Edinger–Westphal (EW) nucleus. Accommodative refractive responses were first measured dynamically with video-based infrared photorefraction and then ocular biometric responses were measured dynamically with continuous ultrasound biometry (CUB) during EW stimulation. The same stimulus amplitudes were used for the refractive and biometric measurements to allow them to be compared. Main sequence relationships (ratio of peak velocity to amplitude) were calculated. Dynamic accommodative refractive changes are linearly correlated with the biometric changes and accommodative biometric changes in ACD, ASL and LT show systematic linear correlations with increasing accommodative amplitudes. The relationships are relatively similar for the eyes of the different monkeys. Dynamic analysis showed that main sequence relationships for both biometry and refraction are linear. Although accommodative refractive changes in the eye occur primarily due to changes in lens surface curvature, the refractive changes are well correlated with A-scan measured accommodative biometric changes. Accommodative changes in ACD, LT and ASL are all well correlated over the full extent of the accommodative response. PMID:15721617

Toxic anterior segment syndrome outbreak after vitrectomy and silicone oil injection.

PubMed

Moisseiev, Elad; Barak, Adiel

2012-01-01

To report a rare outbreak of toxic anterior segment syndrome (TASS) in 4 patients who underwent vitrectomy with silicone oil injection. Review of the medical charts of all patients who underwent surgery in the operating theater of our department during a 10-day period in May 2011. We report on 4 patients who developed TASS after vitrectomy with silicone oil injection. The clinical presentation was typical of TASS, and different from the anterior chamber reaction that may occur after silicone oil injection. All cases were treated effectively with topical steroids, and the outbreak stopped after the silicone oil batch was exchanged. We discuss the possible mechanisms for this unusual TASS outbreak, and suggest the silicone oil as its cause.

Bilateral Herpes Simplex Uveitis: Review of the Literature and Own Reports‏.

PubMed

de-la-Torre, Alejandra; Valdes-Camacho, Juanita; Foster, C Stephen

2017-08-01

Herpes simplex-associated uveitis is usually considered a unilateral eye disease, and rarely included in the differential diagnosis whenever there is bilateral involvement. We report three cases of bilateral herpetic anterior uveitis. We evaluated three patients who presented with clinical manifestations of bilateral uveitis suggestive of viral origin. We found intraocular hypertension, cells in the anterior chamber, paralytic mydriasis, iris atrophy with transillumination defects, and variable anterior vitreous cellularity. According to the clinical findings, supported with herpes-specific antibody titers and aqueous humor PCR results in two of them, they were diagnosed with bilateral anterior herpetic uveitis. Our patients were initially misdiagnosed as having non-infectious uveitis and were treated with immunomodulatory medications, which could have favored the extension of infection bilaterally. Although uncommon, bilateral herpetic uveitis should always be considered in the differential diagnoses, when patients present with hypertensive uveitis in both eyes.

Vertical facial height and its correlation with facial width and depth: Three dimensional cone beam computed tomography evaluation based on dry skulls.

PubMed

Wang, Ming Feng; Otsuka, Takero; Akimoto, Susumu; Sato, Sadao

2013-01-01

The aim of the present study was to evaluate how vertical facial height correlates with mandibular plane angle, facial width and depth from a three dimensional (3D) viewing angle. In this study 3D cephalometric landmarks were identified and measurements from 43 randomly selected cone beam computed tomography (CBCT) images of dry skulls from the Weisbach collection of Vienna Natural History Museum were analyzed. Pearson correlation coefficients of facial height measurements and mandibular plane angle and the correlation coefficients of height-width and height-depth were calculated, respectively. The mandibular plane angle (MP-SN) significantly correlated with ramus height (Co-Go) and posterior facial height (PFH) but not with anterior lower face height (ALFH) or anterior total face height (ATFH). The ALFH and ATFH showed significant correlation with anterior cranial base length (S-N), whereas PFH showed significant correlation with the mandible (S-B) and maxilla (S-A) anteroposterior position. High or low mandibular plane angle might not necessarily be accompanied by long or short anterior face height, respectively. The PFH rather than AFH is assumed to play a key role in the vertical facial type whereas AFH seems to undergo relatively intrinsic growth.

Image-guided intracranial cannula placement for awake in vivo microdialysis in nonhuman primates

NASA Astrophysics Data System (ADS)

Chen, Antong; Bone, Ashleigh; Hines, Catherine D. G.; Dogdas, Belma; Montgomery, Tamara O.; Michener, Maria; Winkelmann, Christopher T.; Ghafurian, Soheil; Lubbers, Laura S.; Renger, John; Bagchi, Ansuman; Uslaner, Jason M.; Johnson, Colena; Zariwala, Hatim A.

2016-03-01

Intracranial microdialysis is used for sampling neurochemicals and large peptides along with their metabolites from the interstitial fluid (ISF) of the brain. The ability to perform this in nonhuman primates (NHP) e.g., rhesus could improve the prediction of pharmacokinetic (PK) and pharmacodynamics (PD) action of drugs in human. However, microdialysis in rhesus brains is not as routinely performed as in rodents. One challenge is that the precise intracranial probe placement in NHP brains is difficult due to the richness of the anatomical structure and the variability of the size and shape of brains across animals. Also, a repeatable and reproducible ISF sampling from the same animal is highly desirable when combined with cognitive behaviors or other longitudinal study end points. Toward that end, we have developed a semi-automatic flexible neurosurgical method employing MR and CT imaging to (a) derive coordinates for permanent guide cannula placement in mid-brain structures and (b) fabricate a customized recording chamber to implant above the skull for enclosing and safeguarding access to the cannula for repeated experiments. In order to place the intracranial guide cannula in each subject, the entry points in the skull and the depth in the brain were derived using co-registered images acquired from MR and CT scans. The anterior/posterior (A/P) and medial-lateral (M/L) rotation in the pose of the animal was corrected in the 3D image to appropriately represent the pose used in the stereotactic frame. An array of implanted fiducial markers was used to transform stereotactic coordinates to the images. The recording chamber was custom fabricated using computer-aided design (CAD), such that it would fit the contours of the individual skull with minimum error. The chamber also helped in guiding the cannula through the entry points down a trajectory into the depth of the brain. We have validated our method in four animals and our results indicate average placement error of cannula to be 1.20 +/- 0.68 mm of the targeted positions. The approach employed here for derivation of the coordinates, surgical implantation and post implant validation is built using traditional access to surgical and imaging methods without the necessity of intra-operative imaging. The validation of our method lends support to its wider application in most nonhuman primate laboratories with onsite MR and CT imaging capabilities.

Fibrinous iritis due to oxybuprocaine.

PubMed Central

Haddad, R

1989-01-01

Following minor surgery performed under topical application of oxybuprocaine (Dorsacaine, Novesin) two patients suffered from fibrinous iritis and moderate corneal swelling. We believe that this represents a toxic reaction caused by an inadvertent entry of this drug into the anterior chamber during the procedure. Images PMID:2920158

21 CFR 886.1660 - Gonioscopic prism.

Code of Federal Regulations, 2010 CFR

2010-04-01

... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior chamber. The device may have angled mirrors to facilitate visualization of anatomical features. (b...

Influence of Ametropia and Its Correction on Measurement of Accommodation.

PubMed

Bernal-Molina, Paula; Vargas-Martín, Fernando; Thibos, Larry N; López-Gil, Norberto

2016-06-01

Amplitude of accommodation (AA) is reportedly greater for myopic eyes than for hyperopic eyes. We investigated potential explanations for this difference. Analytical analysis and computer ray tracing were performed on two schematic eye models of axial ametropia. Using paraxial and nonparaxial approaches, AA was specified for the naked and the corrected eye using the anterior corneal surface as the reference plane. Assuming that axial myopia is due entirely to an increase in vitreous chamber depth, AA increases with the amount of myopia for two reasons that have not always been taken into account. First is the choice of reference location for specifying refractive error and AA in diopters. When specified relative to the cornea, AA increases with the degree of myopia more than when specified relative to the eye's first Gaussian principal plane. The second factor is movement of the eye's second Gaussian principal plane toward the retina during accommodation, which has a larger dioptric effect in shorter eyes. Using the corneal plane (placed at the corneal vertex) as the reference plane for specifying accommodation, AA depends slightly on the axial length of the eye's vitreous chamber. This dependency can be reduced significantly by using a reference plane located 4 mm posterior to the corneal plane. A simple formula is provided to help clinicians and researchers obtain a value of AA that closely reflects power changes of the crystalline lens, independent of axial ametropia and its correction with lenses.

In vivo imaging of kidney glomeruli transplanted into the anterior chamber of the mouse eye

PubMed Central

Kistler, Andreas D.; Caicedo, Alejandro; Abdulreda, Midhat H.; Faul, Christian; Kerjaschki, Dontscho; Berggren, Per-Olof; Reiser, Jochen; Fornoni, Alessia

2014-01-01

Multiphoton microscopy enables live imaging of the renal glomerulus. However, repeated in vivo imaging of the same glomerulus over extended periods of time and the study of glomerular function independent of parietal epithelial and proximal tubular cell effects has not been possible so far. Here, we report a novel approach for non-invasive imaging of acapsular glomeruli transplanted into the anterior chamber of the mouse eye. After microinjection, glomeruli were capable of engrafting on the highly vascularized iris. Glomerular structure was preserved, as demonstrated by podocyte specific expression of cyan fluorescent protein and by electron microscopy. Injection of fluorescence-labeled dextrans of various molecular weights allowed visualization of glomerular filtration and revealed leakage of 70 kDa dextran in an inducible model of proteinuria. Our findings demonstrate functionality and long-term survival of glomeruli devoid of Bowman's capsule and provide a novel approach for non-invasive longitudinal in vivo study of glomerular physiology and pathophysiology. PMID:24464028

Chandelier Illumination for Descemet Membrane Endothelial Keratoplasty

PubMed Central

Hayashi, Takahiko; Yuda, Kentaro; Tsuchiya, Ayako; Oyakawa, Itaru; Mizuki, Nobuhisa; Kato, Naoko

2017-01-01

Purpose: To describe a simple technique that uses posterior chandelier illumination during Descemet membrane endothelial keratoplasty in cases of severe bullous keratopathy (BK). Methods: Five eyes of 4 patients with advanced BK undergoing Descemet membrane endothelial keratoplasty were retrospectively analyzed. The pupil of the host eye was not treated with mydriatic or miotic agents. The chandelier illuminator was inserted transconjunctivally into the vitreous cavity from the pars plana. Results: In all eyes, BK was secondary to laser iridotomy, which was performed for prevention or treatment of angle closure glaucoma. The implanted graft was clearly confirmed in the anterior chamber using activated chandelier illumination. The graft was immediately attached to the host cornea, with eventual healing of BK in all eyes. No complication involving insertion or removal of the 25-gauge trocar and the chandelier illuminator was observed. No vision-threatening complication was observed in any of the 5 eyes. Conclusions: The chandelier illuminator provided good visibility of the anterior chamber and enhanced the safety of surgery by preventing formation of an inverted graft. PMID:28644235

Comparative Analysis of Anterior Chamber Flare Grading between Clinicians with Different Levels of Experience and Semi-automated Laser Flare Photometry.

PubMed

Agrawal, Rupesh; Keane, Pearse A; Singh, Jasmin; Saihan, Zubin; Kontos, Andreas; Pavesio, Carlos E

2016-01-01

To assess correlation for anterior chamber flare grading between clinicians with different levels of experience and with semi-automated flare reading in a cohort of patients with heterogeneous uveitic entities. Fifty-nine observations from 36 patients were recorded and analyzed for statistical association. In each patient, flare was assessed objectively using the Kowa FM-700 laser flare photometer, and subjective masked grading by two clinicians was performed. The study demonstrated disparity in flare readings between clinical graders with one step disagreement in clinical grading in 26 (44.06%) eyes (p < 0.001) and concordance between the flare readings by experienced grader and flare photometry. After review of semi-automated flare readings, management was changed in 11% of the patients. Laser flare photometry can be a valuable tool to remove the observer bias in grading flare for selected cohort of uveitis patients. It can be further applied to titrate therapy in intraocular inflammation.

Fungal corneal ulcer and bacterial orbital cellulitis occur as complications of bacterial endophthalmitis after cataract surgery in an immunocompetent patient.

PubMed

Kim, Eun Chul; Kim, Man Soo; Kang, Nam Yeo

2013-03-01

To report a case of fungal corneal ulcer and bacterial orbital cellulitis as complications of bacterial endophthalmitis following cataract surgery. A 51-year-old man underwent anterior chamber irrigation and aspiration in the left eye one day after cataract surgery because of bacterial endophthalmitis. Marked lid swelling with purulent discharge was developed after 5 days. Slit lamp examination showed generalized corneal ulcer and pus in the total anterior chamber. A computerized tomography scan showed left retrobulbar fat stranding with thickened optic disc. Streptococcus pneumonia was cultured from corneal scraping, vireous, and subconjunctival pus. The patient improved gradually with antibiotics treatments, but the corneal ulcer did not fully recover 2 months after cataract surgery. Candida albicans was detected in repetitive corneal culture. After antifungal and antibacterial therapy, the corneal epithelium had healed, but phthisis bulbi had developed. Fungal corneal ulcer and bacterial orbital cellulitis can occur as complications of endophthalmitis in an immunocompetent patient.

Incisor malalignment and the risk of periodontal disease progression.

PubMed

Alsulaiman, Ahmed A; Kaye, Elizabeth; Jones, Judith; Cabral, Howard; Leone, Cataldo; Will, Leslie; Garcia, Raul

2018-04-01

The objective of this study was to investigate the association between incisor crowding, irregularity, and periodontal disease progression in the anterior teeth. Data collected over 35 years from men enrolled in the Veterans Affairs Dental Longitudinal Study included information concerning pocket depth and alveolar bone loss. Plaster casts of the maxillary (n = 400) and mandibular (n = 408) arches were available for baseline measurements. Periodontal disease in the anterior teeth was defined as per arch sum of pathologic pocket depth and sum of teeth with any alveolar bone loss in the anterior sextants. Incisor malalignment status was defined by the anterior tooth size-arch length discrepancy index and Little's Irregularity Index. Adjusted mixed effects linear models computed the beta (β) estimates and 95% confidence intervals (95% CI) of the amounts of change in periodontal disease outcomes by the level of malalignment. In the anterior maxillary arch, crowding and spacing were significantly associated with an increased per-arch sum of pathologic pocket depth (β, 0.70 mm; 95% CI, 0.20-1.21, and β, 0.49 mm; 95% CI, 0.06-0.91, respectively). In the anterior mandibular arch, incisor crowding and irregularity were significantly associated with an increased per-arch sum of pathologic pocket depth (mild crowding: β, 0.47 mm; 95% CI, 0.01-0.93; severe irregularity: β, 0.94 mm; 95% CI, 0.50-1.38), and the sum number of teeth with alveolar bone loss (mild and moderate-to-severe crowding: β, 0.45 teeth; 95% CI, 0.08-0.82; and β, 0.45 teeth; 95% CI, 0.13-0.83, respectively; moderate irregularity: β, 0.34 teeth; 95% CI, 0.06-0.62). Certain incisor malalignment traits (ie, maxillary incisor crowding, maxillary incisor spacing, mandibular incisor mild crowding, mandibular incisor moderate-to-severe crowding, mandibular incisor moderate irregularity, and mandibular incisor severe irregularity) are associated with significant periodontal disease progression. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Bilateral cataract extraction with posterior chamber intraocular lens implantation simultaneous in pediatric cataracts.

PubMed

Caça, Ihsan; Sakalar, Yildirim Bayezit; Ari, Seyhmus; Alakus, Fuat; Dogan, Eyüp

2008-01-01

We evaluated the results of simultaneous bilateral cataract extraction with intraocular lens (IOL) inplantation 32 pediatric cataract patients. Simultaneous cataract extraction and posterior capsulotomy with anterior vitrectomy and IOL implantation is an effective and safe procedure in bilateral pediatric cataracts treatment.

Limitations of silicon diodes for clinical electron dosimetry.

PubMed

Song, Haijun; Ahmad, Munir; Deng, Jun; Chen, Zhe; Yue, Ning J; Nath, Ravinder

2006-01-01

This work investigates the relevance of several factors affecting the response of silicon diode dosemeters in depth-dose scans of electron beams. These factors are electron energy, instantaneous dose rate, dose per pulse, photon/electron dose ratio and electron scattering angle (directional response). Data from the literature and our own experiments indicate that the impact of these factors may be up to +/-15%. Thus, the different factors would have to cancel out perfectly at all depths in order to produce true depth-dose curves. There are reports of good agreement between depth-doses measured with diodes and ionisation chambers. However, our measurements with a Scantronix electron field detector (EFD) diode and with a plane-parallel ionisation chamber show discrepancies both in the build-up and in the low-dose regions, with a ratio up to 1.4. Moreover, the absolute sensitivity of two diodes of the same EFD model was found to differ by a factor of 3, and this ratio was not constant but changed with depth between 5 and 15% in the low-dose regions of some clinical electron beams. Owing to these inhomogeneities among diodes even of the same model, corrections for each factor would have to be diode-specific and beam-specific. All these corrections would have to be determined using parallel plane chambers, as recommended by AAPM TG-25, which would be unrealistic in clinical practice. Our conclusion is that in general diodes are not reliable in the measurement of depth-dose curves of clinical electron beams.

Characterization of ocular biometrics and aqueous humor dynamics in primary angle closure suspects.

PubMed

Guo, Li; Deng, Yuan; Fang, Li; Liu, Chaoqi; Guo, Tao

2017-02-01

Detailed characterizations of ocular biometrics and parameters of aqueous humor dynamics are lacking in primary angle closure suspect (PACS) patients. This study aims to characterize these parameters and compare them with age-matched healthy volunteers.Elderly healthy volunteers (60.6 ± 7.2 years of age, mean ± SD, n = 28) and PACS patients (64.1 ± 11.6 years, n = 30) completed the study. Parameters investigated were axial length (AXL), anterior chamber depth (ACD), anterior chamber volume (ACV), central cornea thickness (CCT), intraocular pressure (IOP), aqueous flow (Fa), outflow facility (C), episcleral venous pressure (EVP), and uveoscleral outflow (Fu). Comparisons and correlations were made between and within groups.In healthy volunteers, ocular biometric parameters, IOP, and EVP correlated very well between the 2 eyes of each individual, but Fa, C, and Fu were not significantly correlated. Biometric parameters of the PACS group significantly (P < 0.001) differed from those of the healthy controls: AXL (23.31 ± 1.03 mm [PACS] vs 22.39 ± 1.04 mm [Control]; mean ± SD), ACD (2.44 ± 0.33 mm [PACS] vs 1.86 ± 0.25 mm [Control]), ACV (136.0 ± 36.1 μL [PACS] vs 81.4 ± 21.8 μL [Control]), CCT (526.9 ± 37.0 μm [PACS] vs 556.1 ± 28.4 μm [Control]). There was no significant change in IOP, Fa, C, EVP, or Fu between Control and PACS. Furthermore, IOP showed no significant correlations with AXL, ACD, ACV, CCT, or C in both groups.The PACS eyes had a shorter AXL, a shallower ACD, and a smaller ACV, but a thicker CCT. Despite these morphological changes, the PACS eyes did not have any significant changes in IOP, and aqueous humor dynamics parameters. This is consistent with the findings that IOP did not show significant correlations with biometrics, or C.

Comparison of the measurements of a novel optical biometry: Nidek AL-Scan with Sirius and a ultrasound biometry.

PubMed

Çağlar, Çağatay; Kocamış, Sücattin İlker; Demir, Emre; Durmuş, Mustafa

2017-06-01

To investigate the accuracy of the measurements of Nidek AL-Scan by comparing with Sirius (CSO, Florence, Italy), a corneal tomography which also employs the Scheimpflug principle, and a commonly used device, ultrasound biometry (UB) (Aviso A/B, Quantel Medical, MT, USA). Right eyes of 85 healthy volunteers (58 women 27 men) with a mean age of 39.24 ± 14.37 years (range 15-68) were enrolled into this comparative prospective study. Average K 2.4, average K 3.3, CCT (central corneal thickness), WTW (white to white distance), ACD (anterior chamber depth) and AL (axial length) were obtained from the AL-Scan and compared with average SimK, CCT, WTW (horizontal anterior chamber diameter) and ACD obtained from Sirius and also compared with ACD and AL obtained from UB. The statistically significant difference was found between all of the measurements (p < 0.001) except the average keratometry values (K2.4, K3.3, SimK) (p = 0.083). There was a perfect correlation between keratometry, CCT and AL measurements of the devices (ICC = 0.977, 0.954, 0.923, respectively) and there was a strong correlation between the WTW measurements of AL-Scan and Sirius (ICC = 0.865). While ACD parameter of AL-Scan and UB showed a perfect correlation (ICC = 0.977), there was a moderate correlation between AL-Scan and Sirius and also between UB and Sirius (ICC = 0.608 and 0.664, respectively). There was a high correlation between the all measurements, besides ACD, of AL-Scan and Sirius and they can be used interchangeably for average keratometry and WTW confidently. However, ACD and CCT have a broader 95 % LoA (-0.039 to 0.744 and -24.985 to 3.691, respectively). In addition, AL-Scan and UB were in good agreement regarding ACD, while differences in AL measurements of UB and AL-Scan were clinically important (95 % LoA = -0.091 to 0.703). Furthermore, UB and Sirius have a moderate agreement regarding ACD (95 % LoA = -0.047 to 0.680).

Structural and functional characterization of the contractile aorta and associated hemocytes of the mosquito Anopheles gambiae.

PubMed

Sigle, Leah T; Hillyer, Julián F

2018-06-22

The primary pump of the circulatory system of insects is a dorsal vessel that traverses the length of the insect. The anterior portion, located in the head, neck and thorax, is the aorta, and the posterior portion, located in the abdomen, is the heart. Here, we characterize the structure and function of the aorta and conical chamber of the mosquito, Anopheles gambiae The aorta begins in the head with an excurrent opening located above the dorsal pharyngeal plate and ends at the thoraco-abdominal junction where it joins the conical chamber of the heart. The aorta lacks ostia, and based on the diameter of the vessel as well as the density and helical orientation of muscle, consists of three regions: the anterior aorta, the bulbous chamber, and the posterior aorta. The aorta contracts in the anterograde direction, but these contractions are independent of heart contractions and do not play a major role in hemolymph propulsion. Intravital imaging of the venous channels, the first abdominal segment and the neck revealed that hemolymph only travels through the aorta in the anterograde direction, and does so only during periods of anterograde heart flow. Furthermore, hemolymph only enters the thoraco-abdominal ostia of the conical chamber when the heart contracts in the retrograde direction, propelling this hemolymph to the posterior of the body. Finally, very few hemocytes associate with the aorta, and unlike what is seen in the periostial regions of the heart, infection does not induce the aggregation of hemocytes on the aorta. © 2018. Published by The Company of Biologists Ltd.

Estimation of axial curvature of anterior sclera: correlation between axial length and anterior scleral curvature as affected by angle kappa.

PubMed

Lee, Sang-Mok; Choi, Hyuk Jin; Choi, Heejin; Kim, Mee Kum; Wee, Won Ryang

2016-10-07

BACKGROUND: Though the development and fitting of scleral contact lenses are expanding steadily, there is no simple method to provide scleral metrics for scleral contact lens fitting yet. The aim of this study was to establish formulae for estimation of the axial radius of curvature (ARC) of the anterior sclera using ocular biometric parameters that can be easily obtained with conventional devices. A semi-automated stitching method and a computational analysis tool for calculating ARC were developed by using the ImageJ and MATLAB software. The ARC of all the ocular surface points were analyzed from the composite horizontal cross-sectional images of the right eyes of 24 volunteers; these measurements were obtained using anterior segment optical coherence tomography for a previous study (AS-OCT; Visante). Ocular biometric parameters were obtained from the same volunteers with slit-scanning topography and partial coherence interferometry. Correlation analysis was performed between the ARC at 8 mm to the axis line (ARC[8]) and other ocular parameters (including age). With ARC obtained on several nasal and temporal points (7.0, 7.5, 8.0, 8.5, and 9.0 mm from the axis line), univariate and multivariate linear regression analyses were performed to develop a model for estimating ARC with the help of ocular biometric parameters. Axial length, spherical equivalent, and angle kappa showed correlations with temporal ARC[8] (tARC[8]; Pearson's r = 0.653, -0.579, and -0.341; P = 0.001, 0.015, and 0.015, respectively). White-to-white corneal diameter (WTW) and anterior chamber depth (ACD) showed correlation with nasal ARC[8] (nARC[8]; Pearson's r = -0.492 and -0.461; P = 0.015 and 0.023, respectively). The formulae for estimating scleral curvatures (tARC, nARC, and average ARC) were developed as a function of axial length, ACD, WTW, and distance from the axis line, with good determinant power (72 - 80 %; SPSS ver. 22.0). Angle kappa showed strong correlation with axial length (Pearson's r = -0.813, P <0.001), and the different correlation patterns of nasal and temporal ARC with axial length can be explained by the ocular surface deviation represented by angle kappa. Axial length, ACD, and WTW are useful parameters for estimating the ARC of the anterior sclera, which is important for the haptic design of scleral contact lenses. Angle kappa affects the discrepancies between the nasal and temporal scleral curvature.

MO-FG-CAMPUS-IeP1-05: New Ionization Chamber Dosimetry of Absorbed Dose to Water in Diagnostic KV X-Ray Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Araki, F; Ohno, T

Purpose: To develop new ionization chamber dosimetry of absorbed dose to water in diagnostic kV x-ray beams, by using a beam quality conversion factor, kQ, for Co-60 to kV x-ray and an ionization conversion factor for a water-substitute plastic phantom. Methods: kQ was calculated for aluminum half value-layers (Al-HVLs) of 1.5 mm to 8 mm which were generated by kV x-ray beams of 50 to 120 kVp. Twenty-two energy spectra for ten effective energies (Eeff) were calculated by a SpecCalc program. Depth doses in water were calculated at 5 × 5 to 30 × 30 cm{sup 2} fields. Output factorsmore » were also obtained from the dose ratio for a 10 × 10 cm{sup 2} field. kQ was obtained for a PTW30013 Former ion chamber. In addition, an ionization conversion factor of the PWDT phantom to water was calculated. All calculations were performed with EGSnrc/cavity code and egs-chamber codes. Results: The x-ray beam energies for 1.5 mm to 8 mm Al-HVLs ranged in Eeff of 25.7 to 54.3 keV. kQ for 1.5 mm to 8 mm Al-HVLs were 0.831 to 0.897, at 1 and 2 cm depths for a 10 × 10 cm2 field. Similarly, output factors for 5 × 5 to 30 × 30 cm{sup 2} fields were 0.937 to 1.033 for 25.7 keV and 0.857 to 1.168 for 54.3 keV. The depth dose in a PWDT phantom decreased up to 5% compared to that in water at depth of ten percent of maximum dose for 1.5 mm Al-HVL. The ionization ratios of water/PWDT phantoms for the PTW30013 chamber were 1.012 to 1.007 for 1.5 mm to 8 mm Al-HVLs at 1 cm depth. Conclusion: It became possible to directly measure the absorbed dose to water with the ionization chamber in diagnostic kV x-ray beams, by using kQ and the PWDT phantom.« less

Effect of depth on shear-wave elastography estimated in the internal and external cervical os during pregnancy

PubMed Central

Hernandez-Andrade, Edgar; Aurioles-Garibay, Alma; Garcia, Maynor; Korzeniewski, Steven J.; Schwartz, Alyse G.; Ahn, Hyunyoung; Martinez-Varea, Alicia; Yeo, Lami; Chaiworapongsa, Tinnakorn; Hassan, Sonia S.; Romero, Roberto

2014-01-01

Aim To investigate the effect of depth on cervical shear-wave elastography. Methods Shear-wave elastography was applied to estimate the velocity of propagation of the acoustic force impulse (shear-wave) in the cervix of 154 pregnant women at 11-36 weeks of gestation. Shear-wave speed (SWS) was evaluated in cross-sectional views of the internal and external cervical os in five regions of interest: anterior, posterior, lateral right, lateral left, and endocervix. Distance from the center of the US transducer to the center of the each region of interest was registered. Results In all regions, SWS decreased significantly with gestational age (p=0.006). In the internal os SWS was similar among the anterior, posterior and lateral regions, and lower in the endocervix. In the external os, the endocervix and anterior regions showed similar SWS values, lower than those from the posterior and lateral regions. In the endocervix, these differences remained significant after adjustment for depth, gestational age and cervical length. SWS estimations in all regions of the internal os were higher than those of the external os, suggesting denser tissue. Conclusion Depth from the ultrasound probe to different regions in the cervix did not significantly affect the SWS estimations. PMID:25029081

Intraocular lens power estimation by accurate ray tracing for eyes underwent previous refractive surgeries

NASA Astrophysics Data System (ADS)

Yang, Que; Wang, Shanshan; Wang, Kai; Zhang, Chunyu; Zhang, Lu; Meng, Qingyu; Zhu, Qiudong

2015-08-01

For normal eyes without history of any ocular surgery, traditional equations for calculating intraocular lens (IOL) power, such as SRK-T, Holladay, Higis, SRK-II, et al., all were relativley accurate. However, for eyes underwent refractive surgeries, such as LASIK, or eyes diagnosed as keratoconus, these equations may cause significant postoperative refractive error, which may cause poor satisfaction after cataract surgery. Although some methods have been carried out to solve this problem, such as Hagis-L equation[1], or using preoperative data (data before LASIK) to estimate K value[2], no precise equations were available for these eyes. Here, we introduced a novel intraocular lens power estimation method by accurate ray tracing with optical design software ZEMAX. Instead of using traditional regression formula, we adopted the exact measured corneal elevation distribution, central corneal thickness, anterior chamber depth, axial length, and estimated effective lens plane as the input parameters. The calculation of intraocular lens power for a patient with keratoconus and another LASIK postoperative patient met very well with their visual capacity after cataract surgery.

Interruption of Transmission of Onchocerca volvulus in the Oaxaca Focus, Mexico

PubMed Central

Rodríguez-Pérez, Mario A.; Unnasch, Thomas R.; Domínguez-Vázquez, Alfredo; Morales-Castro, Alba L.; Peña-Flores, Graciela P.; Orozco-Algarra, María E.; Arredondo-Jiménez, Juan I.; Richards, Frank; Vásquez-Rodríguez, Miguel A.; Rendón, Vidal García

2010-01-01

All endemic communities of the Oaxaca focus of onchocerciasis in southern Mexico have been treated annually or semi-annually with ivermectin since 1994. In-depth epidemiologic assessments were performed in communities during 2007 and 2008. None of the 52,632 Simulium ochraceum s.l. collected in four sentinel communities was found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), resulting in an upper bound of the infection rate in the vectors of 0.07/2,000. The prevalence of microfilariae (mf) in the cornea and/or anterior chamber of the eye was also zero (0 of 1,039 residents examined; 95%-UL = 0.35%). Similarly, all 1,164 individuals examined by skin biopsy were mf negative (95%-UL = 0.31%), and sera collected from 3,569 children from 25 communities did not harbor Ov16 IgG4-antibodies (95%-UL = 0.09%). These meet the criteria for absence of morbidity and parasite transmission in the Oaxaca focus. As a result mass treatments with ivermectin were halted in 2009. PMID:20595472

In vivo confocal microscopic analysis of normal human anterior limbal stroma

PubMed Central

Mathews, Saumi; Chidambaram, Jaya Devi; Lanjewar, Shruti; Mascarenhas, Jeena; Prajna, Namperumalsamy Venkatesh; Muthukkaruppan, Veerappan; Chidambaranathan, Gowri Priya

2015-01-01

Purpose To characterize the microarchitecture of the anterior limbal stroma in healthy individuals using in vivo confocal microscopy (IVCM) and to correlate it with mesenchymal stem cells (MSCs), a component of the limbal-niche. Methods The corneal side of the superior limbus was scanned in 30 eyes of 17 normal subjects beyond the basal epithelium, deep into the stroma using a HRT III laser scanning microscope. The IVCM findings were correlated with the immunohistochemical features of MSCs in the anterior limbal stroma. Results Clusters of hyperreflective structures were observed in the anterior limbal stroma, subjacent to the basal epithelium (depth: 50.2±8.7 - 98±12.8 μm), but not in the corneal stroma. The structures showed unique morphology compared to epithelial cells, keratocytes, neurons and dendritic cells. In parallel, confocal analysis of immunostained sections showed clusters of cells, double positive for MSC specific markers (CD90 and CD105) in the anterior limbal stroma at a depth of 55.3±12.7 μm to 72±37.6 μm. The organization and distribution of the MSC clusters locates them within the hyperreflective region in the anterior limbal stroma. Conclusions The hyperreflective structures, demonstrated for the first time in the human anterior limbal stroma, probably represent an important component of the limbal-niche. Our approach of in vivo imaging may pave the way for assessing the limbal stromal health. PMID:25742388

Nongranulomatous anterior uveitis in a patient with Usher syndrome.

PubMed

Alzuhairy, Sultan Abdulaziz S; Alfawaz, Abdullah

2013-10-01

A 34-year-old female with Usher syndrome, but no family history of similar illness, presented with complaints of vision reduction, redness, and photophobia. Biomicroscopic examination showed mildly injected conjunctivae bilateral, small, round keratic precipitates; bilateral +2 cells with no flare reaction in the anterior chamber; and bilateral posterior subcapsular cataracts. No associated posterior synechiae, angle neovascularization, or iris changes were detected; normal intraocular pressures were obtained. Fundus examination demonstrated waxy pallor of both optic nerves, marked vasoconstriction in retinal vessels, and retinal bone spicule pigment formation, with a normal macula. Electroretinography confirmed the diagnosis of retinitis pigmentosa, optical coherent tomography was normal and otolaryngology consultation was conducted. To our knowledge, an association between Usher syndrome and bilateral nongranulomatous anterior uveitis has not been previously reported, and our purpose is to report this association.

Anterior-segment imaging for assessment of glaucoma

PubMed Central

Ursea, Roxana; Silverman, Ronald H

2010-01-01

This article summarizes the physics, technology and clinical application of ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT) for assessment of the anterior segment in glaucoma. UBM systems use frequencies ranging from approximately 35 to 80 MHz, as compared with typical 10-MHz systems used for general-purpose ophthalmic imaging. OCT systems use low-coherence, near-infrared light to provide detailed images of anterior segment structures at resolutions exceeding that of UBM. Both technologies allow visualization of the iridocorneal angle and, thus, can contribute to the diagnosis and management of glaucoma. OCT systems are advantageous, being noncontact proceedures and providing finer resolution than UBM, but UBM systems are superior for the visualization of retroiridal structures, including the ciliary body, posterior chamber and zonules, which can provide crucial diagnostic information for the assessment of glaucoma. PMID:20305726

A perspective of gene therapy in the glaucomas.

PubMed

Kaufman, P L; Jia, W W; Tan, J; Chen, Z; Gabelt, B T; Booth, V; Tufaro, F; Cynader, M

1999-06-01

Gene therapy in the anterior and posterior segment tissues may have the potential to favorably influence aqueous hydrodynamics and retinal ganglion cell biology, thereby preventing, delaying, or minimizing glaucomatous damage to the optic nerve. We demonstrated the feasibility of using a herpes viral vector (ribonucleotide reductase defective HSV-1, hrR3) to deliver the lacZ reporter gene to living cat and rat eyes. Cats received injections into the anterior chamber and rats into the vitreous cavity. In cats, lacZ expression was detectable at 1 to 2 days in the anterior outer portion of the ciliary muscle and the lining of the intertrabecular spaces of the corneoscleral and uveal meshwork. Rat eyes showed lacZ expression in the retinal pigment epithelium and photoreceptor outer segments 2 days after injection.

Nonpenetrating glaucoma surgery with goniosynechiolysis ab interno: a surgical technique.

PubMed

Mirshahi, A; Scharioth, G B

2009-01-01

To present a surgical technique for treatment of peripheral anterior synechiae (PAS or goniosynechiae) at the operative field during nonpenetrating glaucoma surgery. After usual preparation of a superficial and a deep scleral flap with externalization of the Schlemm's canal and peeling the juxtacanalicular trabecular meshwork, the goniosynechia is transected by a spatula introduced to the anterior chamber through a paracentesis. A Descemet's window provides full visual control at the peripheral cornea at the basis of the superficial scleral flap. With this surgical technique, selective treatment of goniosynechiae is possible exactly at the area where creation of low outflow resistance is intended by the surgeon during nonpenetrating glaucoma surgery. This technique enables the surgeon to perform nonpenetrating glaucoma surgery even in the presence of peripheral anterior synechiae.

Learning micro incision surgery without the learning curve

PubMed Central

Navin, Shoba; Parikh, Rajul

2008-01-01

We describe a method of learning micro incision cataract surgery painlessly with the minimum of learning curves. A large-bore or standard anterior chamber maintainer (ACM) facilitates learning without change of machine or preferred surgical technique. Experience with the use of an ACM during phacoemulsification is desirable. PMID:18292624

Forecasting magma-chamber rupture at Santorini volcano, Greece

PubMed Central

Browning, John; Drymoni, Kyriaki; Gudmundsson, Agust

2015-01-01

How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection, and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily cause an eruption but produces a net volume change that can be measured geodetically by inversion techniques. Using continuum-mechanics and fracture-mechanics principles, we calculate the amount of magma contained at shallow depth beneath Santorini volcano, Greece. We demonstrate through structural analysis of dykes exposed within the Santorini caldera, previously published data on the volume of recent eruptions, and geodetic measurements of the 2011–2012 unrest period, that the measured 0.02% increase in volume of Santorini’s shallow magma chamber was associated with magmatic excess pressure increase of around 1.1 MPa. This excess pressure was high enough to bring the chamber roof close to rupture and dyke injection. For volcanoes with known typical extrusion and intrusion (dyke) volumes, the new methodology presented here makes it possible to forecast the conditions for magma-chamber failure and dyke injection at any geodetically well-monitored volcano. PMID:26507183

Toward optimizing patient-specific IMRT QA techniques in the accurate detection of dosimetrically acceptable and unacceptable patient plans

PubMed Central

McKenzie, Elizabeth M.; Balter, Peter A.; Stingo, Francesco C.; Jones, Jimmy; Followill, David S.; Kry, Stephen F.

2014-01-01

Purpose: The authors investigated the performance of several patient-specific intensity-modulated radiation therapy (IMRT) quality assurance (QA) dosimeters in terms of their ability to correctly identify dosimetrically acceptable and unacceptable IMRT patient plans, as determined by an in-house-designed multiple ion chamber phantom used as the gold standard. A further goal was to examine optimal threshold criteria that were consistent and based on the same criteria among the various dosimeters. Methods: The authors used receiver operating characteristic (ROC) curves to determine the sensitivity and specificity of (1) a 2D diode array undergoing anterior irradiation with field-by-field evaluation, (2) a 2D diode array undergoing anterior irradiation with composite evaluation, (3) a 2D diode array using planned irradiation angles with composite evaluation, (4) a helical diode array, (5) radiographic film, and (6) an ion chamber. This was done with a variety of evaluation criteria for a set of 15 dosimetrically unacceptable and 9 acceptable clinical IMRT patient plans, where acceptability was defined on the basis of multiple ion chamber measurements using independent ion chambers and a phantom. The area under the curve (AUC) on the ROC curves was used to compare dosimeter performance across all thresholds. Optimal threshold values were obtained from the ROC curves while incorporating considerations for cost and prevalence of unacceptable plans. Results: Using common clinical acceptance thresholds, most devices performed very poorly in terms of identifying unacceptable plans. Grouping the detector performance based on AUC showed two significantly different groups. The ion chamber, radiographic film, helical diode array, and anterior-delivered composite 2D diode array were in the better-performing group, whereas the anterior-delivered field-by-field and planned gantry angle delivery using the 2D diode array performed less well. Additionally, based on the AUCs, there was no significant difference in the performance of any device between gamma criteria of 2%/2 mm, 3%/3 mm, and 5%/3 mm. Finally, optimal cutoffs (e.g., percent of pixels passing gamma) were determined for each device and while clinical practice commonly uses a threshold of 90% of pixels passing for most cases, these results showed variability in the optimal cutoff among devices. Conclusions: IMRT QA devices have differences in their ability to accurately detect dosimetrically acceptable and unacceptable plans. Field-by-field analysis with a MapCheck device and use of the MapCheck with a MapPhan phantom while delivering at planned rotational gantry angles resulted in a significantly poorer ability to accurately sort acceptable and unacceptable plans compared with the other techniques examined. Patient-specific IMRT QA techniques in general should be thoroughly evaluated for their ability to correctly differentiate acceptable and unacceptable plans. Additionally, optimal agreement thresholds should be identified and used as common clinical thresholds typically worked very poorly to identify unacceptable plans. PMID:25471949

Toward optimizing patient-specific IMRT QA techniques in the accurate detection of dosimetrically acceptable and unacceptable patient plans.

PubMed

McKenzie, Elizabeth M; Balter, Peter A; Stingo, Francesco C; Jones, Jimmy; Followill, David S; Kry, Stephen F

2014-12-01

The authors investigated the performance of several patient-specific intensity-modulated radiation therapy (IMRT) quality assurance (QA) dosimeters in terms of their ability to correctly identify dosimetrically acceptable and unacceptable IMRT patient plans, as determined by an in-house-designed multiple ion chamber phantom used as the gold standard. A further goal was to examine optimal threshold criteria that were consistent and based on the same criteria among the various dosimeters. The authors used receiver operating characteristic (ROC) curves to determine the sensitivity and specificity of (1) a 2D diode array undergoing anterior irradiation with field-by-field evaluation, (2) a 2D diode array undergoing anterior irradiation with composite evaluation, (3) a 2D diode array using planned irradiation angles with composite evaluation, (4) a helical diode array, (5) radiographic film, and (6) an ion chamber. This was done with a variety of evaluation criteria for a set of 15 dosimetrically unacceptable and 9 acceptable clinical IMRT patient plans, where acceptability was defined on the basis of multiple ion chamber measurements using independent ion chambers and a phantom. The area under the curve (AUC) on the ROC curves was used to compare dosimeter performance across all thresholds. Optimal threshold values were obtained from the ROC curves while incorporating considerations for cost and prevalence of unacceptable plans. Using common clinical acceptance thresholds, most devices performed very poorly in terms of identifying unacceptable plans. Grouping the detector performance based on AUC showed two significantly different groups. The ion chamber, radiographic film, helical diode array, and anterior-delivered composite 2D diode array were in the better-performing group, whereas the anterior-delivered field-by-field and planned gantry angle delivery using the 2D diode array performed less well. Additionally, based on the AUCs, there was no significant difference in the performance of any device between gamma criteria of 2%/2 mm, 3%/3 mm, and 5%/3 mm. Finally, optimal cutoffs (e.g., percent of pixels passing gamma) were determined for each device and while clinical practice commonly uses a threshold of 90% of pixels passing for most cases, these results showed variability in the optimal cutoff among devices. IMRT QA devices have differences in their ability to accurately detect dosimetrically acceptable and unacceptable plans. Field-by-field analysis with a MapCheck device and use of the MapCheck with a MapPhan phantom while delivering at planned rotational gantry angles resulted in a significantly poorer ability to accurately sort acceptable and unacceptable plans compared with the other techniques examined. Patient-specific IMRT QA techniques in general should be thoroughly evaluated for their ability to correctly differentiate acceptable and unacceptable plans. Additionally, optimal agreement thresholds should be identified and used as common clinical thresholds typically worked very poorly to identify unacceptable plans.

Drilling through lateral transmuscular portal lowers the risk of suprascapular nerve injury during arthroscopic SLAP repair.

PubMed

Kocaoglu, Baris; Ulku, Tekin Kerem; Sayilir, Safiye; Ozbaydar, Mehmet Ugur; Bayramoglu, Alp; Karahan, Mustafa

2017-10-01

The aim of our study was to evaluate the risk of medial glenoid perforation and possible injury to suprascapular nerve during arthroscopic SLAP repair using lateral transmuscular portal. Ten cadaveric shoulder girdles were isolated and drilled at superior glenoid rim from both anterior-superior portal (1 o'clock) and lateral transmuscular portal (12 o'clock) for SLAP repairs. Drill hole depth was determined by the manufacturer's drill stop (20 mm), and any subsequent drill perforations through the medial bony surface of the glenoid were directly confirmed by dissection. The bone tunnel depth and subsequent distance to the suprascapular nerve, scapular height and width, were compared for investigated locations. Four perforations out of ten (40 %) occurred through anterior-superior portal with one associated nerve injury. One perforation out of ten (10 %) occurred through lateral transmuscular portal without any nerve injury. The mean depth was calculated as 17.6 mm (SD 3) for anterior-superior portal and 26.5 mm (SD 3.6) for lateral transmuscular portal (P < 0.001). It is anatomically possible that suprascapular nerve could sustain iatrogenic injury during labral anchor placement during SLAP repair. However, lateral transmuscular portal at 12 o'clock drill entry location has lower risk of suprascapular nerve injury compared with anterior-superior portal at 1 o'clock drill entry location.

Sexual dimorphism of the internal mandibular chamber in Fayum Pliohyracidae (Mammalia)

USGS Publications Warehouse

de Blieux, D.D.; Baumrind, M.R.; Simons, E.L.; Chatrath, P.S.; Meyer, G.E.; Attia, Y.S.

2006-01-01

An internal mandibular fenestra and chamber are found in many fossil hyracoids. The internal mandibular fenestra is located on the lingual surface of the mandibular corpus and opens into a chamber within the mandible. The mandibular chamber is maximally developed in late Eocene Thyrohyrax meyeri and early Oligocene Thyrohyrax domorictus from the Fayum Province of Egypt. The function of this chamber is unknown as it is not found in extant hyraxes, nor is it known to occur in any other mammal. In Thyrohyrax, this feature appears to be sexually dimorphic because it is confined to roughly one half of the specimens that otherwise cannot be separated by dental characteristics or measurements. It has been suggested that the chamber is found in females based on the presumed distribution of this character in other fossil hyracoids. Fossils from Fayum Quarry L-41, preserving the sexually dimorphic anterior dentition, show that, in Thyrohyrax meyeri and Thyrohyrax domorictus, the internal mandibular chamber is found in males. In Thyrohyrax litholagus, an internal mandibular fenestra and inflated mandibular chamber occurs in males whereas females show the variable presence of an internal mandibular fossa or fenestra but lack an expanded chamber. Other genera show differing patterns of sexual variation in which some Fayum hyracoids have an internal mandibular fenestra in both sexes but with the greatest development of the mandibular chamber occurring in males. We review functions proposed for the internal mandibular chamber and suggest that it housed a laryngeal air sac that may have had a vocal function by acting as a resonating chamber. ?? 2006 by the Society of Vertebrate Paleontology.

A high-resolution 3D ultrasonic system for rapid evaluation of the anterior and posterior segment.

PubMed

Peyman, Gholam A; Ingram, Charles P; Montilla, Leonardo G; Witte, Russell S

2012-01-01

Traditional ultrasound imaging systems for ophthalmology employ slow, mechanical scanning of a single-element ultrasound transducer. The goal was to demonstrate rapid examination of the anterior and posterior segment with a three-dimensional (3D) commercial ultrasound system incorporating high-resolution linear probe arrays. The 3D images of the porcine eye were generated in approximately 10 seconds by scanning one of two commercial linear arrays (25- and 50-MHz). Healthy enucleated pig eyes were compared with those with induced injury or placement of a foreign material (eg, metal). Rapid, volumetric imaging was also demonstrated in one human eye in vivo. The 50-MHz probe provided exquisite volumetric images of the anterior segment at a depth up to 15 mm and axial resolution of 30 μm. The 25-MHz probe provided a larger field of view (lateral X depth: 20 × 30 mm), sufficient for capturing the entire anterior and posterior segments of the pig eye, at a resolution of 60 μm. A 50-MHz scan through the human eyelid illustrated detailed structures of the Meibomian glands, cilia, cornea, and anterior segment back to the posterior capsule. The 3D system with its high-frequency ultrasound arrays, fast data acquisition, and volume rendering capability shows promise for investigating anterior and posterior structures of the eye. Copyright 2012, SLACK Incorporated.

A quantitative method for studying human arterial baroreflexes

NASA Technical Reports Server (NTRS)

Eckberg, Dwain L.; Fritsch, Janice M.; Goble, Ross L.

1991-01-01

A new system is described that delivers precise, stereotyped pressure changes to the human neck and elicits neurally-mediated heart rate changes. The centerpiece of this system is a Silastic chamber that is strapped to the anterior neck. This chamber is connected to a stepping-motor-controlled bellows assembly. A strain-gauge transducer measures the intensity of pressure changes. The entire system is controlled by microprocessors, and both stimuli and responses are displayed on a digital oscilloscope. The end-product of this system is a reproducible baroreceptor stimulus-cardiac response relation that can be recorded rapidly and safely in astronauts in space.

Iris coloboma in one eye and pigment dispersion syndrome in the fellow eye.

PubMed

Galvis, Virgilio; Tello, Alejandro; Valarezo, Paul; Prada, Angélica M

2013-05-22

We report a case of a 43-year-old patient with coloboma of the iris, zonule, ciliary body, choroid and retina in the right eye and pigment dispersion syndrome in the left eye. Considering the hypothesis of the pigment dispersion syndrome pathogenesis in which a difference of pressures in the anterior and posterior chambers creates a posterior convexity of the iris leading to reverse pupillary block, iris touch and consequently causing pigment dispersion, we suggest that the presence of an iris coloboma, by equalising the pressures in the two chambers, prevented the onset of syndrome in that eye.

Unilateral uveitis masquerade syndrome caused by diffuse large B-cell lymphoma diagnosed using multiparametric flow cytometry of the aqueous humor.

PubMed

Monsalvo, Silvia; Serrano, Cristina; Prieto, Elena; Fernández-Sanz, Guillermo; Puente, Maria-Camino; Rodriguez-Pinilla, Maria; Garcia Raso, Aranzazu; Llamas, Pilar; Cordoba, Raul

2017-07-01

The uveitis masquerade syndromes (UMS) are a group of ocular diseases that may mimic chronic intraocular inflammation. Many malignant entities such as non-Hodgkin's lymphomas may masquerade as uveitis. We report a case of an HIV-positive patient with masquerade syndrome presenting unilateral uveitis. 45-year-old Caucasian man with a diagnosis of diffuse large B-cell lymphoma (DLBCL). The patient was diagnosed by a biopsy of an abdominal mass which showed fragments of gastric mucosa with diffuse growth of neoplastic cells. At diagnosis, the patient suffered from unilateral blurring of vision and a sudden decrease of left-eye visual acuity. A slit-lamp examination of the left eye revealed a diagnosis of anterior uveitis. The patient exhibited no signs of posterior uveitis. An anterior-chamber paracentesis was performed and analyzed by multiparameter flow cytometry (MFC), showing cells CD45, CD19, CD20, CD22, and CD38 positives, and moderate expression of CD10 with kappa light chain restriction, showing a monoclonal B-cell population. The patient received CHOP-R with intrathecal methotrexate followed by consolidation high dose methotrexate obtaining a complete response which is ongoing. Differential diagnosis between chronic uveitis and ocular lymphoma may be challenging. We advocate anterior-chamber paracentesis in cases of refractory uveitis in patients with hematologic malignancies. © 2016 International Clinical Cytometry Society. © 2016 International Clinical Cytometry Society.

On the use of unshielded cables in ionization chamber dosimetry for total-skin electron therapy.

PubMed

Chen, Z; Agostinelli, A; Nath, R

1998-03-01

The dosimetry of total-skin electron therapy (TSET) usually requires ionization chamber measurements in a large electron beam (up to 120 cm x 200 cm). Exposing the chamber's electric cable, its connector and part of the extension cable to the large electron beam will introduce unwanted electronic signals that may lead to inaccurate dosimetry results. While the best strategy to minimize the cable-induced electronic signal is to shield the cables and its connector from the primary electrons, as has been recommended by the AAPM Task Group Report 23 on TSET, cables without additional shielding are often used in TSET dosimetry measurements for logistic reasons, for example when an automatic scanning dosimetry is used. This paper systematically investigates the consequences and the acceptability of using an unshielded cable in ionization chamber dosimetry in a large TSET electron beam. In this paper, we separate cable-induced signals into two types. The type-I signal includes all charges induced which do not change sign upon switching the chamber polarity, and type II includes all those that do. The type-I signal is easily cancelled by the polarity averaging method. The type-II cable-induced signal is independent of the depth of the chamber in a phantom and its magnitude relative to the true signal determines the acceptability of a cable for use under unshielded conditions. Three different cables were evaluated in two different TSET beams in this investigation. For dosimetry near the depth of maximum buildup, the cable-induced dosimetry error was found to be less than 0.2% when the two-polarity averaging technique was applied. At greater depths, the relative dosimetry error was found to increase at a rate approximately equal to the inverse of the electron depth dose. Since the application of the two-polarity averaging technique requires a constant-irradiation condition, it was demonstrated than an additional error of up to 4% could be introduced if the unshielded cable's spatial configuration were altered during the two-polarity measurements. This suggests that automatic scanning systems with unshielded cables should not be used in TSET ionization chamber dosimetry. However, the data did show that an unshielded cable may be used in TSET ionization chamber dosimetry if the size of cable-induced error in a given TSET beam is pre-evaluated and the measurement is carefully conducted. When such an evaluation has not been performed, additional shielding should be applied to the cable being used, making measurements at multiple points difficult.

Determinants of lens vault and association with narrow angles in patients from Singapore.

PubMed

Tan, Gavin S; He, Mingguang; Zhao, Wanting; Sakata, Lisandro M; Li, Jialiang; Nongpiur, Monisha E; Lavanya, Raghavan; Friedman, David S; Aung, Tin

2012-07-01

To describe the distribution and determinants of lens vault and to investigate the association of lens vault with narrow angles. Prospective cross-sectional study. Phakic subjects 50 years and older were evaluated at a primary healthcare clinic with gonioscopy, partial laser interferometry, and anterior segment optical coherence tomography (AS-OCT). Narrow angles were defined as posterior trabecular meshwork not visible for ≥2 quadrants on non-indentation gonioscopy. Lens vault was defined as the perpendicular distance between the anterior pole of the crystalline lens and the horizontal line joining the 2 scleral spurs on horizontal AS-OCT scans. Analysis of covariance, multivariate logistic regression, and area under the receiver operating characteristic curves (AUC) were performed. Of the 2047 subjects recruited, 582 were excluded because of poor image quality or inability to locate scleral spurs, leaving 1465 subjects for analysis. Eyes with narrow angles had greater lens vault compared to eyes with open angles (775.6 µm vs 386.5 µm, P < .0001). Women had significantly greater lens vault than men (497.28 µm vs 438.56 µm, P < .001), and lens vault increased significantly with age (P for trend <.001). Adjusted for age and sex, significant associations with greater lens vault were shorter axial length, shallower anterior chamber depth(ACD), higher intraocular pressure, and more hyperopic spherical equivalent (all P < .001). On multivariate analysis, subjects with lens vault >667.6 µm were more likely to have narrow angles (OR 2.201, 95% CI: 1.070-4.526) compared to those with lens vault ≤462.7 µm. The AUC for lens vault (0.816) and ACD (0.822) for detecting narrow angles were similar (P = .582). Lens vault was independently associated with narrow angles and may be useful in screening to detect eyes with narrow angles. Copyright © 2012 Elsevier Inc. All rights reserved.

Immediate implants placed into infected sockets: a case report with 3-year follow-up.

PubMed

Naves, Marina de Melo; Horbylon, Bruna Zacharias; Gomes, Camila de Freitas; Menezes, Helder Henrique Machado de; Bataglion, César; Magalhães, Denildo de

2009-01-01

The esthetics and functional integrity of the periodontal tissue may be compromised by dental loss. Immediate implants became a viable option to maintain the periodontal architecture because of their anatomic compatibility with the dental socket and the possibility of eliminating local contamination. This article describes the procedure of immediate implant placement in the anterior maxilla replacing teeth with chronic periapical lesions, which were condemned due to endodontic lesions persisting after failed endodontic treatment and endodontic surgery, and discusses the relationship between the procedure and periapical lesions. Surgical removal of hopeless teeth 11, 12 and 21 was performed conservatively in such a way to preserve the anatomy and gingival esthetics. A second surgical access was gained at the apical level, allowing the debridement of the surgical chamber for elimination of the periapical lesion, visual orientation for setting of the implants and filling of the surgical chamber with xenogenous bovine bone graft. After this procedure, the bone chamber was covered with an absorbent membrane and the healing screws were positioned on the implants. Later, a provisional partial removable denture was installed and the implants were inserted after 6 months. After 3 years of rehabilitation, the implants present satisfactory functional and esthetic conditions, suggesting that immediate implant placement combined with guided bone regeneration may be indicated for replacing teeth lost due to chronic periapical lesions with endodontic failure history in the anterior maxilla.

Comparison of gonioscopy and anterior segment ocular coherence tomography in detecting angle closure in different quadrants of the anterior chamber angle.

PubMed

Sakata, Lisandro M; Lavanya, Raghavan; Friedman, David S; Aung, Han T; Gao, Hong; Kumar, Rajesh S; Foster, Paul J; Aung, Tin

2008-05-01

To compare the performance of gonioscopy and anterior segment (AS) optical coherence tomography (OCT) in detecting angle closure in the different quadrants of the anterior chamber angle (ACA). Cross-sectional observational study. Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic problems recruited from a community clinic in Singapore. All subjects underwent gonioscopy and AS OCT imaging in the dark. Using gonioscopy, the ACA was graded using the Scheie system by a single examiner masked to AS OCT findings. The ACA in a particular quadrant was classified as closed if the posterior trabecular meshwork could not be seen on gonioscopy. A closed ACA on AS OCT imaging was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. After excluding eyes with poor image quality, a total of 423 right eyes were included in the analysis. A closed angle in at least 1 quadrant was observed in 59% of the eyes by AS OCT and in 33% of the eyes by gonioscopy (P<0.001), with fair agreement between the two methods (kappa = 0.40). The frequency of closed angles by AS OCT and gonioscopy were 48% versus 29% superiorly, 43% versus 22% inferiorly, 18% versus 14% nasally, and 12% versus 20% temporally, respectively. Of the 119 of 1692 quadrants that were closed on gonioscopy but open on AS OCT, a steep iris profile was present in 61 (51%) of 119 quadrants on AS OCT, and of the 276 of 1692 quadrants that were open on gonioscopy but closed on AS OCT, 196 (71%) of 276 quadrants showed short iridoangle contact on AS OCT. The highest rates of closed angles on gonioscopy and AS OCT images were observed in the superior quadrant. Anterior segment OCT tended to detect more closed ACAs than gonioscopy, particularly in the superior and inferior quadrants. Variations in the iris profile and level of iridoangle contact also may explain some of the differences seen between gonioscopy and AS OCT.

Anterior segment photography in pediatric eyes using the Lytro light field handheld noncontact camera.

PubMed

Marcus, Inna; Tung, Irene T; Dosunmu, Eniolami O; Thiamthat, Warakorn; Freedman, Sharon F

2013-12-01

To compare anterior segment findings identified in young children using digital photographic images from the Lytro light field camera to those observed clinically. This was a prospective study of children <9 years of age with an anterior segment abnormality. Clinically observed anterior segment examination findings for each child were recorded and several digital images of the anterior segment of each eye captured with the Lytro camera. The images were later reviewed by a masked examiner. Sensitivity of abnormal examination findings on Lytro imaging was calculated and compared to the clinical examination as the gold standard. A total of 157 eyes of 80 children (mean age, 4.4 years; range, 0.1-8.9) were included. Clinical examination revealed 206 anterior segment abnormalities altogether: lids/lashes (n = 21 eyes), conjunctiva/sclera (n = 28 eyes), cornea (n = 71 eyes), anterior chamber (n = 14 eyes), iris (n = 43 eyes), and lens (n = 29 eyes). Review of Lytro photographs of eyes with clinically diagnosed anterior segment abnormality correctly identified 133 of 206 (65%) of all abnormalities. Additionally, 185 abnormalities in 50 children were documented at examination under anesthesia. The Lytro camera was able to document most abnormal anterior segment findings in un-sedated young children. Its unique ability to allow focus change after image capture is a significant improvement on prior technology. Copyright © 2013 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

A systematic Monte Carlo study of secondary electron fluence perturbation in clinical proton beams (70-250 MeV) for cylindrical and spherical ion chambers.

PubMed

Verhaegen, F; Palmans, H

2001-10-01

Current dosimetry protocols for clinical protons do not take into account any secondary electron fluence perturbation in ion chambers. In this work, we performed a systematic study of secondary electron fluence perturbation factors for spherical and cylindrical ion chambers in proton beams (70-250 MeV). The electron fluence perturbation factor, pe, was calculated using Monte Carlo transport of protons and secondary electrons. The influence of proton energy, cavity wall material (graphite, water, A150, PMMA, polystyrene), cavity radius, cavity wall thickness and positioning depth in water is studied. The influence of inelastic nuclear proton interactions is briefly discussed. It was found that pe depends on wall material; the largest values for pe were obtained for ion chambers with A150 walls (pe=1.009), the smallest values for graphite walls. The perturbation factor was found to be largely independent of proton energy. A slight decrease of pe with cavity radius was obtained, especially for low energy protons. The wall thickness was found to have no effect on pe in the range studied (0.025-0.1 cm). The depth of the cavity in a water phantom was also found to have an insignificant effect on pe. Based on the results in the paper for spherical and cylindrical ion chambers, a method to calculate pe for a thimble ion chamber is presented. The results presented in this paper for cylindrical and spherical ion chambers are in contradiction to the calculated electron fluence perturbation factors for planar ion chambers in the paper by Casnati et al.

Full ocular biometry through dual-depth whole-eye optical coherence tomography

PubMed Central

Kim, Hyung-Jin; Kim, Minji; Hyeon, Min Gyu; Choi, Youngwoon; Kim, Beop-Min

2018-01-01

We propose a new method of determining the optical axis (OA), pupillary axis (PA), and visual axis (VA) of the human eye by using dual-depth whole-eye optical coherence tomography (OCT). These axes, as well as the angles “α” between the OA and VA and “κ” between PA and VA, are important in many ophthalmologic applications, especially in refractive surgery. Whole-eye images are reconstructed based on simultaneously acquired images of the anterior segment and retina. The light from a light source is split into two orthogonal polarization components for imaging the anterior segment and retina, respectively. The OA and PA are identified based on their geometric definitions by using the anterior segment image only, while the VA is detected through accurate correlation between the two images. The feasibility of our approach was tested using a model eye and human subjects. PMID:29552378

Imaging of the iridocorneal angle with the RTVue spectral domain optical coherence tomography.

PubMed

Perera, Shamira A; Ho, Ching Lin; Aung, Tin; Baskaran, Mani; Ho, Henrietta; Tun, Tin A; Lee, Tian Loon; Kumar, Rajesh S

2012-04-02

To determine the ability of the RTVue spectral domain optical coherence tomography (SDOCT) to image the anterior chamber angle (ACA). Consecutive subjects, recruited from glaucoma clinics, prospectively underwent ophthalmic evaluation including gonioscopy by an ophthalmologist and anterior chamber imaging with SDOCT, adapted with a corneal lens adapter (cornea anterior module-low magnification [CAM-L]) and anterior segment OCT (ASOCT), both performed by a technician. Two different ophthalmologists, masked to gonioscopy findings, assessed visualization of the scleral spur (SS), Schwalbe's line (SL), and trabecular meshwork (TM) by the two modalities. The ability to detect a closed angle was compared with gonioscopy. The average age (SD) of the 81 subjects enrolled was 64.1 (11.4) years; the majority were Chinese (91.4%) and female (61.7%). SDOCT images revealed the SS in 26.9% (56/324) of quadrants and the SL in 44.1% (143/324) of quadrants; in ASOCT images, the SS could be visualized in 69.1% (224/324) of quadrants (P < 0.0001), but the SL was undetectable. The TM was detected equally well (17.3%, P < 0.92) using either device. The angle status was gradable in only 41.7% images with SDOCT, compared with 71.3% of ASOCT images (P < 0.0001). ACA was classified as closed in 19.3% of quadrants (26/135) with SDOCT images and in 44.2% (102/231) with ASOCT images compared with 37.7% (122/324) on gonioscopy. When analyzing the horizontal quadrants only, both modalities agreed well with gonioscopy, 0.75 and 0.74, respectively (AC1 statistics). The RTVue SDOCT allowed visualization of SL, TM, and SS. However, these landmarks were not detected in a large percentage of images.

Golimumab in refractory uveitis related to spondyloarthritis. Multicenter study of 15 patients.

PubMed

Calvo-Río, Vanesa; Blanco, Ricardo; Santos-Gómez, Montserrat; Rubio-Romero, Esteban; Cordero-Coma, Miguel; Gallego-Flores, Adela; Veroz, Raúl; Torre, Ignacio; Hernández, Félix Francisco; Atanes, Antonio; Loricera, Javier; González-Vela, M C; Palmou, Natalia; Hernández, José L; González-Gay, Miguel A

2016-08-01

To assess the efficacy of golimumab (GLM) in refractory uveitis associated to spondyloarthritis (SpA). Multicenter study of SpA-related uveitis refractory to at least 1 immunosuppressive drug. The main outcome variables were degree of anterior and posterior chamber inflammation, visual acuity, and macular thickness. A total of 15 patients (13 men/2 women; 18 affected eyes; mean age 39 ± 6 years) were evaluated. The underlying SpA subtypes were ankylosing spondylitis (n = 8), psoriatic arthritis (n = 6) and non-radiographic axial SpA (n = 1). The ocular involvement patterns were recurrent anterior uveitis in 8 patients and chronic anterior uveitis in 7. Before GLM they have received methotrexate (n = 13), sulfasalazine (n = 6), pulses of methylprednisolone (n = 4), azathioprine (n = 3), leflunomide (n = 2), and cyclosporine (n = 1). Overall, 10 of them had also been treated with TNF-α blockers; etanercept (n = 7), adalimumab (n = 7), infliximab (n = 6), and certolizumab (n = 1). GLM was given at the standard dose (50mg/sc/monthly) as monotherapy (n = 7) or in combination with conventional immunosuppressive drugs (n = 8), mainly methotrexate. Most patients had rapid and progressive improvement of intraocular inflammation parameters. The median number of cells in the anterior chamber at 2 years [0 (0-0)] was significantly reduced compared to baseline findings [1 (0-3); p = 0.04]. The mean best corrected visual acuity value also improved (0.84 ± 0.3 at 2 years versus 0.62 ± 0.3 at baseline; p = 0.03). Only minor side effects were observed after a mean follow-up of 23 ± 7 months. Our results indicate that GLM may be a useful therapeutic option in refractory SpA-related uveitis. Copyright © 2016 Elsevier Inc. All rights reserved.

Insulin acts as a powerful stimulator of axial myopia in chicks.

PubMed

Feldkaemper, Marita P; Neacsu, Irina; Schaeffel, Frank

2009-01-01

In animal models, it has been shown that the retina can use the defocus of the projected image to control emmetropization. Glucagon may be involved in the sign of defocus detection, at least in chickens. Since glucagon and insulin often have opposite effects in metabolic pathways, the effect of insulin on eye growth was investigated. Chicks were treated with either positive or negative spectacle lenses and intravitreally injected with saline or different amounts of insulin. Refraction, axial length, and corneal curvature were measured. Effects of insulin on vitreal glucose concentration, on retinal ZENK and glucagon mRNA levels, and on the number of ZENK-immunoreactive glucagon amacrine cells were studied. Insulin injections (0.3 nmol) caused only a small myopic shift in control chicks. When positive lenses were worn, insulin injections (0.3; 0.03 nmol) not only blocked hyperopia but rather induced high amounts of axial myopia. Insulin also enhanced myopia that was induced by negative lenses. Axial elongation was mostly due to an increase in anterior chamber depth and a thickening of the crystalline lens. Insulin temporarily reduced vitreal glucose levels. Insulin increased retinal ZENK mRNA levels, whereas the number of ZENK-immunoreactive glucagon amacrine cells was reduced, a finding that is typically linked to the development of myopia. Given that insulin is used in therapy for human metabolic disorders and has been proposed to treat corneal epithelial disease, its powerful myopiagenic effect, which is mostly due to its effects on the optics of the anterior segment of the eye, merits further investigation.

Poster — Thur Eve — 21: Off-axis dose perturbation effects in water in a 5 × 5 cm{sup 2} 18 MV photon beam for the PTW microLion and Exradin A1SL ionization chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Grady, K; Davis, S D; Papaconstadopoulos, P

2014-08-15

A PTW microLion liquid ionization chamber and an Exradin A1SL air-filled ionization chamber have been modeled using the egs-chamber user code of the EGSnrc system to determine their perturbation effects in water in a 5 × 5 cm{sup 2} 18 MV photon beam. A model of the Varian CL21EX linear accelerator was constructed using the BEAMnrc Monte Carlo code, and was validated by comparing measured PDDs and profiles from the microLion and A1SL chambers to calculated results that included chamber models. Measured PDDs for a 5 × 5 cm{sup 2} field for the microLion chamber agreed with calculations to withinmore » 1.5% beyond a depth of 0.5 cm, and the A1SL PDDs agreed within 1.0% beyond 1.0 cm. Measured and calculated profiles at 10 cm depth agreed within 1.0% for both chambers inside the field, and within 4.0% near the field edge. Local percent differences increased up to 15% at 4 cm outside the field. The ratio of dose to water in the absence of the chamber relative to dose in the chamber's active volume as a function of off-axis distance was calculated using the egs-chamber correlated sampling technique. The dose ratio was nearly constant inside the field and consistent with the stopping power ratios of water to detector material, but varied up to 3.3% near the field edge and 5.2% at 4 cm outside the field. Once these perturbation effects are fully characterized for more field sizes and detectors, they could be applied to clinical water tank measurements for improved dosimetric accuracy.« less

Surgical extraction of intraocular Parelaphostrongylus tenuis (Nematoda: Metastrongyloidea) in a horse

USDA-ARS?s Scientific Manuscript database

Case Description – A 4-year-old Hanoverian horse from Wisconsin presented for evaluation of a worm-like structure in the anterior chamber of the right eye. Clinical Findings – Ophthalmic examination of the right eye revealed a white, thin, mobile parasite, presumably a nematode, present in the ventr...

Impaired swim bladder inflation in early-life stage fathead minnows exposed to a deiodinase inhibitor, iopanoic acid (article)

EPA Science Inventory

The present study investigated whether inhibition of deiodinase, the enzyme which converts thyroxine (T4) to the more biologically-active form, 3,5,3'-triiodothyronine (T3), would impact inflation of the posterior and/or anterior chamber of the swim bladder, processes previously ...

Impaired swim bladder inflation in early-life stage fathead minnows exposed to a deiodinase inhibitor, iopanoic acid (presentation)

EPA Science Inventory

The present study investigated whether inhibition of deiodinase, the enzyme which converts thyroxine (T4) to the more biologically-active form, 3,5,3'-triiodothyronine (T3), would impact inflation of the posterior and/or anterior chamber of the swim bladder, processes previously ...

Intraocular gnathostomiasis from coastal part of Maharashtra.

PubMed

Sujata, Dharmshale N; Renu, Bharadwaj S

2013-01-01

Intraocular infestation by live Gnathostoma spinigerum is a rare occurrence in humans. Most of the published reports are from South-East Asia. We report a case of ocular gnathostomiasis from Western Maharashtra, where the worm was removed live from the anterior chamber of the left eye. Identification of the worm was confirmed by light microscopy.

21 CFR 886.1660 - Gonioscopic prism.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior chamber...

21 CFR 886.1660 - Gonioscopic prism.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior chamber...

21 CFR 886.1660 - Gonioscopic prism.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior chamber...

21 CFR 886.1660 - Gonioscopic prism.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior chamber...

The albino chick as a model for studying ocular developmental anomalies, including refractive errors, associated with albinism.

PubMed

Rymer, Jodi; Choh, Vivian; Bharadwaj, Shrikant; Padmanabhan, Varuna; Modilevsky, Laura; Jovanovich, Elizabeth; Yeh, Brenda; Zhang, Zhan; Guan, Huanxian; Payne, W; Wildsoet, Christine F

2007-10-01

Albinism is associated with a variety of ocular anomalies including refractive errors. The purpose of this study was to investigate the ocular development of an albino chick line. The ocular development of both albino and normally pigmented chicks was monitored using retinoscopy to measure refractive errors and high frequency A-scan ultrasonography to measure axial ocular dimensions. Functional tests included an optokinetic nystagmus paradigm to assess visual acuity, and flash ERGs to assess retinal function. The underlying genetic abnormality was characterized using a gene microarray, PCR and a tyrosinase assay. The ultrastructure of the retinal pigment epithelium (RPE) was examined using transmission electron microscopy. PCR confirmed that the genetic abnormality in this line is a deletion in exon 1 of the tyrosinase gene. Tyrosinase gene expression in isolated RPE cells was minimally detectable, and there was minimal enzyme activity in albino feather bulbs. The albino chicks had pink eyes and their eyes transilluminated, reflecting the lack of melanin in all ocular tissues. All three main components, anterior chamber, crystalline lens and vitreous chamber, showed axial expansion over time in both normal and albino animals, but the anterior chambers of albino chicks were consistently shallower than those of normal chicks, while in contrast, their vitreous chambers were longer. Albino chicks remained relatively myopic, with higher astigmatism than the normally pigmented chicks, even though both groups underwent developmental emmetropization. Albino chicks had reduced visual acuity yet the ERG a- and b-wave components had larger amplitudes and shorter than normal implicit times. Developmental emmetropization occurs in the albino chick but is impaired, likely because of functional abnormalities in the RPE and/or retina as well as optical factors. In very young chicks the underlying genetic mutation may also contribute to refractive error and eye shape abnormalities.

Intra-ocular pressure normalization technique and equipment

NASA Technical Reports Server (NTRS)

Mcgannon, W. J. (Inventor)

1980-01-01

A method and apparatus for safely reducing abnormally high intraocular pressure in an eye during a predetermined time interval is presented. This allows maintenance of normal intraocular pressure during glaucoma surgery. According to the invention, a pressure regulator of the spring biased diaphragm type is provided with additional bias by a column of liquid. The height of the column of liquid is selected such that the pressure at a hypodermic needle connected to the output of the pressure regulator is equal to the measured pressure of the eye. The hypodermic needle can then be safely inserted into the anterior chamber of the eye. Liquid is then bled out of the column to reduce the bias on the diaphragm of the pressure regulator and, consequently, the output pressure of the regulator. This lowering pressure of the regulator also occurs in the eye by means of a small second bleed path provided between the pressure regulator and the hypodermic needle. Alternately, a second hypodermic needle may be inserted into the eye to provide a controlled leak off path for excessive pressure and clouded fluid from the anterior chamber.

Transverse depth-dependent changes in corneal collagen lamellar orientation and distribution

PubMed Central

Abass, Ahmed; Hayes, Sally; White, Nick; Sorensen, Thomas; Meek, Keith M.

2015-01-01

It is thought that corneal surface topography may be stabilized by the angular orientation of out-of plane lamellae that insert into the anterior limiting membrane. In this study, micro-focus X-ray scattering data were used to obtain quantitative information about lamellar inclination (with respect to the corneal surface) and the X-ray scatter intensity throughout the depth of the cornea from the centre to the temporal limbus. The average collagen inclination remained predominantly parallel to the tissue surface at all depths. However, in the central cornea, the spread of inclination angles was greatest in the anterior-most stroma (reflecting the increased lamellar interweaving in this region), and decreased with tissue depth; in the peripheral cornea inclination angles showed less variation throughout the tissue thickness. Inclination angles in the deeper stroma were generally higher in the peripheral cornea, suggesting the presence of more interweaving in the posterior stroma away from the central cornea. An increase in collagen X-ray scatter was identified in a region extending from the sclera anteriorly until about 2 mm from the corneal centre. This could arise from the presence of larger diameter fibrils, probably of scleral origin, which are known to exist in this region. Incorporation of this quantitative information into finite-element models will further improve the accuracy with which they can predict the biomechanical response of the cornea to pathology and refractive procedures. PMID:25631562

Constraints on the depth and geometry of the magma chamber of the Olympus Mons Volcano, Mars

NASA Technical Reports Server (NTRS)

Zuber, Maria T.; Mouginis-Mark, Peter J.

1990-01-01

The summit caldera of the Olympus Mons volcano exhibits one of the clearest examples of tectonic processes associated with shield volcanism on Mars. The radial distance from the center of the transition from concentric ridges to concentric graben within the oldest crater provides a constraint on the geometry and depth of the subsurface magmatic reservoir at the time of subsidence. Here, researchers use this constraint to investigate the size, shape, and depth of the reservoir. Their approach consists of calculating radial surface stresses corresponding to the range of subsurface pressure distributions representing an evacuating magma chamber. They then compare stress patterns to the observed radial positions of concentric ridges and graben. The problem is solved by employing the finite element approach using the program TECTON.

High-resolution ultrasound imaging of the eye – a review

PubMed Central

Silverman, Ronald H

2009-01-01

This report summarizes the physics, technology and clinical application of ultrasound biomicroscopy (UBM) of the eye, in which frequencies of 35 MHz and above provide over a threefold improvement in resolution compared with conventional ophthalmic ultrasound systems. UBM allows imaging of anatomy and pathology involving the anterior segment, including regions obscured by overlying optically opaque anatomic or pathologic structures. UBM provides diagnostically significant information in conditions such as glaucoma, cysts and neoplasms, trauma and foreign bodies. UBM also can provide crucial biometric information regarding anterior segment structures, including the cornea and its constituent layers and the anterior and posterior chambers. Although UBM has now been in use for over 15 years, new technologies, including transducer arrays, pulse encoding and combination of ultrasound with light, offer the potential for significant advances in high-resolution diagnostic imaging of the eye. PMID:19138310

Uveitis induced by programmed cell death protein 1 inhibitor therapy with nivolumab in metastatic melanoma patient.

PubMed

Kanno, Hiroaki; Ishida, Kyoko; Yamada, Wataru; Nishida, Takashi; Takahashi, Nobumichi; Mochizuki, Kiyofumi; Mizuno, Yuki; Matsuyama, Kanako; Takahashi, Tomoko; Seishima, Mariko

2017-11-01

Nivolumab, a new immune checkpoint inhibitor, binds to programmed cell death-protein 1 receptors on T cell, blockades binding of its ligands, and augments the immunologic reaction against tumor cells. Augmented immune response, however, may lead to immune-related adverse events. Herein we describe a rare case of bilateral anterior uveitis induced by nivolumab treatment for metastatic melanoma. A 54-year-old woman presented with mild conjunctival redness and blurred vision two months after initiating nivolumab treatment. Ophthalmological examination revealed bilateral non-granulomatous anterior uveitis. The flare values in the anterior chamber were monitored as an objective inflammatory index during nivolumab therapy and clinical time course was reported in this paper. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

High-resolution ultrasound imaging of the eye - a review.

PubMed

Silverman, Ronald H

2009-01-01

This report summarizes the physics, technology and clinical application of ultrasound biomicroscopy (UBM) of the eye, in which frequencies of 35 MHz and above provide over a threefold improvement in resolution compared with conventional ophthalmic ultrasound systems. UBM allows imaging of anatomy and pathology involving the anterior segment, including regions obscured by overlying optically opaque anatomic or pathologic structures. UBM provides diagnostically significant information in conditions such as glaucoma, cysts and neoplasms, trauma and foreign bodies. UBM also can provide crucial biometric information regarding anterior segment structures, including the cornea and its constituent layers and the anterior and posterior chambers. Although UBM has now been in use for over 15 years, new technologies, including transducer arrays, pulse encoding and combination of ultrasound with light, offer the potential for significant advances in high-resolution diagnostic imaging of the eye.

Serial corneal endothelial cell loss with lathe-cut and injection-molded posterior chamber intraocular lenses.

PubMed

Kraff, M C; Sanders, D R; Lieberman, H L

1983-01-01

We compared endothelial cell loss of patients implanted with lathe-cut posterior chamber lenses and those implanted with injection-molded lenses over a three-year postoperative period. Results were based on more than 2,500 measurements of corneal endothelial density. Although the technique of cataract extraction (anterior chamber phacoemulsification, posterior chamber phacoemulsification, or planned extracapsular extraction) significantly affected cell loss (P less than .01), the type of implant (lathe-cut or injection-molded) did not. Significant continuing endothelial cell loss did not occur during the first three postoperative years with injection-molded lenses. There was, however, a statistically significant 7% to 15% additional cell loss after surgery over the first two to three postoperative years with lathe-cut implants. There have been no cases of corneal endothelial decompensation developing after implantation of injection-molded or lathe-cut lenses. Because a standard field clinical specular microscope was used in this study, cell counting errors cannot be ruled out as a cause of these findings.

Conductive heat transfer from an isothermal magma chamber and its application to the measured heat flow distribution from mount hood, Oregon

USGS Publications Warehouse

Nathenson, Menuel; Tilling, Robert I.; ,

1993-01-01

A steady-state solution for heat transfer from an isothermal, spherical magma chamber, with an imposed regional geothermal gradient far from the chamber, is developed. The extensive published heat-flow data set for Mount Hood, Oregon, is dominated by conductive heat transfer in the deeper parts of most drill holes and provides an ideal application of such a model. Magma-chamber volumes or depths needed to match the distribution of heat-flow data are larger or shallower than those inferred from geologic evidence.

Plate Versus Intramedullary Nail Fixation of Anterior Tibial Stress Fractures: A Biomechanical Study.

PubMed

Markolf, Keith L; Cheung, Edward; Joshi, Nirav B; Boguszewski, Daniel V; Petrigliano, Frank A; McAllister, David R

2016-06-01

Anterior midtibial stress fractures are an important clinical problem for patients engaged in high-intensity military activities or athletic training activities. When nonoperative treatment has failed, intramedullary (IM) nail and plate fixation are 2 surgical options used to arrest the progression of a fatigue fracture and allow bone healing. A plate will be more effective than an IM nail in preventing the opening of a simulated anterior midtibial stress fracture from tibial bending. Controlled laboratory study. Fresh-frozen human tibias were loaded by applying a pure bending moment in the sagittal plane. Thin transverse saw cuts, 50% and 75% of the depth of the anterior tibial cortex, were created at the midtibia to simulate a fatigue fracture. An extensometer spanning the defect was used to measure the fracture opening displacement (FOD) before and after the application of IM nail and plate fixation constructs. IM nails were tested without locking screws, with a proximal screw only, and with proximal and distal screws. Plates were tested with unlocked bicortical screws (standard compression plate) and locked bicortical screws; both plate constructs were tested with the plate edge placed 1 mm from the anterior tibial crest (anterior location) and 5 mm posterior to the crest. For the 75% saw cut depth, the mean FOD values for all IM nail constructs were 13% to 17% less than those for the saw cut alone; the use of locking screws had no significant effect on the FOD. The mean FOD values for all plate constructs were significantly less than those for all IM nail constructs. The mean FOD values for all plates were 28% to 46% less than those for the saw cut alone. Anterior plate placement significantly decreased mean FOD values for both compression and locked plate constructs, but the mean percentage reductions for locked and unlocked plates were not significantly different from each other for either plate placement. The percentage FOD reductions for all plate constructs and the unlocked IM nail were significantly less with a 50% saw cut depth. Plate fixation was superior to IM nail fixation in limiting the opening of a simulated midtibial stress fracture, and anterior-posterior placement of the plate was an important variable for this construct. Results from these tests can help guide the selection of fixation hardware for patients requiring surgical treatment for a midtibial stress fracture. © 2016 The Author(s).

Predictors of femtosecond laser intrastromal astigmatic keratotomy efficacy for astigmatism management in cataract surgery.

PubMed

Day, Alexander C; Stevens, Julian D

2016-02-01

To evaluate the factors associated with the efficacy of femtosecond laser intrastromal astigmatic keratotomy (AK). Moorfields Eye Hospital, London, United Kingdom. Prospective case series. Eyes having intrastromal AK for corneal cylinder correction were analyzed. Preoperative biometric parameters included axial length, anterior chamber depth, central corneal thickness, and Ocular Response Analyzer corneal hysteresis (CH) and corneal resistance factor (CRF). Preoperative and 1-month postoperative corneal keratometry was measured using the Topcon KR8100PA topographer-autorefractor. Astigmatic analyses were performed using the Alpins method. The study analyzed 319 eyes of 213 patients with a mean target induced astigmatism of 1.24 diopters (D) ± 0.44 (SD), mean surgically induced astigmatism (SIA) of 0.71 ± 0.43 D, and mean difference vector of 0.79 ± 0.41 D. Two multiple regression models were constructed for SIA prediction. Model 1, based on previous manual limbal relaxing incision parameters, confirmed age and astigmatism meridian (with/against the rule and oblique) to be associated with SIA in addition to AK arc length, AK start depth, and preoperative corneal cylinder magnitude. Model 2, additionally considering other parameters, found only lower CH (-0.06 DC per unit CH), a higher CRF (0.04 D per unit CRF), and the astigmatism meridian to be independent predictors of greater SIA (after adjusting for intrastromal AK arc length, start depth, and preoperative corneal cylinder). With-the-rule astigmatism was associated with a 0.13 D higher SIA than against-the-rule astigmatism, holding all other variables constant. Corneal biomechanical parameters and astigmatism meridian were independent predictors of femtosecond laser intrastromal AK efficacy even after adjusting for AK arc length, AK start depth, and preoperative corneal cylinder. Dr. Stevens is a previous consultant to Optimedica, Inc. which is now part of Abbott Medical Optics, Inc. Drs. Stevens and Day have no financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

A study on the suitability of the PTW microDiamond detector for kilovoltage x-ray beam dosimetry.

PubMed

Damodar, Joshita; Odgers, David; Pope, Dane; Hill, Robin

2018-05-01

Kilovoltage x-ray beams are widely used in treating skin cancers and in biological irradiators. In this work, we have evaluated four dosimeters (ionization chambers and solid state detectors) in their suitability for relative dosimetry of kilovoltage x-ray beams in the energy range of 50 - 280kVp. The solid state detectors, which have not been investigated with low energy x-rays, were the PTW 60019 microDiamond synthetic diamond detector and the PTW 60012 diode. The two ionization chambers used were the PTW Advanced Markus parallel plate chamber and the PTW PinPoint small volume chamber. For each of the dosimeters, percentage depth doses were measured in water over the full range of x-ray beams and for field sizes ranging from 2cm diameter to 12 × 12cm. In addition, depth doses were measured for a narrow aperture (7mm diameter) using the PTW microDiamond detector. For comparison, the measured data was compared with Monte Carlo calculated doses using the EGSnrc Monte Carlo package. The depth dose results indicate that the Advanced Markus parallel plate and PinPoint ionization chambers were suitable for depth dose measurements in the beam quality range with an uncertainty of less than 3%, including in the regions closer to the surface of the water as compared with Monte Carlo depth dose data for all six energy beams. The response of the PTW Diode E detector was accurate to within 4% for all field sizes in the energy range of 50-125kVp but showed larger variations for higher energies of up to 12% with the 12 × 12cm field size. In comparison, the microDiamond detector had good agreement over all energies for both smaller and larger field sizes generally within 1% as compared to the Advanced Markus chamber field and Monte Carlo calculations. The only exceptions were in measuring the dose at the surface of the water phantom where larger differences were found. For the 7mm diameter field, the agreement between the microDiamond detector and Monte Carlo calculations was good being better than 1% except at the surface. Based on these results, the PTW microDiamond detector has shown to be a suitable detector for relative dosimetry of low energy x-ray beams over a wide range of x-ray beam energies. Copyright © 2018 Elsevier Ltd. All rights reserved.

Grooved Glaucoma Drainage Devices That Continuously Deliver Cyclosporine A Decrease Postsurgical Scar Formation in Rabbit Eyes.

PubMed

Dai, Zhaoxing; Yu, Xiaobo; Sun, Jianguo; Sun, Xinghuai

2017-03-01

To study the functional outcomes of filtration surgery by implanting improved glaucoma drainage devices (GDDs) comprising surface grooves and a composite coating of cyclosporine A (CsA) and PLGA in experimental rabbit eyes. Improved GDDs were designed and prepared by modifying normal GDD with surface grooves and a CsA-PLGA composite coating. Normal GDDs, grooved GDDs (G-GDDs), and G-GDDs with a CsA-PLGA composite coating (CsA@G-GDD) were implanted into 18 rabbit eyes (six eyes per group). The intraocular pressure (IOP), bleb survival time, bleb morphology, and anterior chamber reactions were assessed for up to 12 weeks after GDD implantation. The IOPs were compared statistically among the three groups. Bleb morphology was quantified using the Indiana Bleb Appearance Grading Scale. Anterior chamber radiography was performed to check whether the filtrating pathway was blocked, and determine the drainage time and diffusion area of the contrast agent. Hematoxylin and eosin staining and immunohistochemistry were conducted to assess how the GDDs slowed or prevented scar formation. The improved GDDs were successfully prepared and implanted in 18 rabbit eyes without severe surgical complications. Bleb survival time was significantly longer and IOP was significantly lower in the G-GDD and CsA@G-GDD groups compared with the GDD group (all, P < 0.001). Blebs were significantly higher in the CsA@G-GDD group than in the GDD and G-GDD groups (P = 0.003). Anterior chamber radiography revealed more unobstructed filtration channels in the CsA@G-GDD group than in the GDD group (P = 0.032). Postsurgical scar formation was less extensive in the G-GDD and CsA@G-GDD groups than in the GDD group. Compared with the normal GDDs, G-GDDs with a CsA-PLGA coating inhibited postsurgical scar formation and improved the surgical success rate, and might represent an alternative to existing glaucoma filtration devices.

The South Asian cataract management study: complications, vision outcomes, and corneal endothelial cell loss in a randomized multicenter clinical trial comparing intracapsular cataract extraction with and without anterior chamber intraocular lens implantation.

PubMed

Snellingen, T; Shrestha, J K; Huq, F; Husain, R; Koirala, S; Rao, G N; Pokhrel, R P; Kolstad, A; Upadhyay, M P; Apple, D J; Arnesen, E; Cheng, H; Olsen, E G; Vogel, M

2000-02-01

To determine clinical outcomes of primary intracapsular cataract surgery with and without implantation of anterior chamber lenses. A multicenter randomized clinical trial. One thousand two hundred twenty-nine male and female patients 40-75 years of age with senile cataract. Study patients were recruited from screening eye camps and outpatient clinics. Randomization to the two treatment groups was performed after screening for predetermined inclusion and exclusion criteria. Demographics, visual acuity, intraocular pressures, and corneal endothelial cell data were recorded before surgery and at 6 weeks, 12 months, and 24 months after surgery. Monitoring of the study was secured by a standardized image documentation procedure on all patients using the IMAGEnet digital imaging system. Analysis of corneal endothelial cell images was performed with the Cell Soft software (Topcon Corporation, Japan). Visual acuity and central corneal endothelial cell loss. The patients were randomized to intraocular lens (IOL; n = 616) and no IOL (n = 613) implantation. Surgical complications were reported in 177 (14.4%) patients (IOL = 14.8%; no IOL = 14.0%). The most frequent complication observed was vitreous loss which occurred in 10.3% of eyes (IOL = 11.2%; no IOL = 9.5%). At the final examination (2 years after surgery), 88% of the operated eyes had a best corrected vision of 6/18 or better (IOL = 88.8%; no IOL = 86.6%). Analysis of corneal endothelial cell data showed a small but significantly greater cell loss 6 weeks after surgery in eyes with IOL compared with those without IOL, but no overall difference was found between the treatment groups in the long term follow-up. The findings indicate that there is a rationale for the use of anterior chamber intraocular lenses in primary intracapsular cataract surgery.

Assessing the Agreement Between Radiologic and Clinical Measurements of Lumbar and Cervical Epidural Depths in Patients Undergoing Prone Interlaminar Epidural Steroid Injection.

PubMed

Jones, James Harvey; Singh, Naileshni; Nidecker, Anna; Li, Chin-Shang; Fishman, Scott

2017-05-01

Fluoroscopy-guided epidural steroid injection (ESI) commonly is performed to treat radicular pain yet can lead to adverse events if the needle is not advanced with precision. Accurate preoperative assessment of the distance from the skin to the epidural space holds the potential for reducing the risks of adverse effects from ESI. It was hypothesized that the distance from the skin to the epidural space as measured on preoperative magnetic resonance imaging (MRI) would agree with the distance traveled by a Tuohy needle to reach the epidural space during midline, interlaminar ESI. This study compared the final needle depth measurement at the point of loss of resistance (LOR) from cervical or lumbar ESI to the distance from the skin to the anterior and posterior borders of the epidural space on the associated cervical and lumbar preoperative MRI. This retrospective chart review analyzed the procedure notes, MRI, and demographic data of patients who received a prone, interlaminar ESI at an outpatient chronic pain clinic between June 1, 2013, and June 1, 2015. The following data were collected: body mass index (BMI), age, sex, intervertebral level of the ESI, and LOR depth. We then measured the distance from the skin surface to the anterior border of the ligamentum flavum (ligamentum flavum depth [LFD]) and dura (dura depth [DD]) on MRI. A total of 335 patients were categorized into the following patient subgroups: age ≥65 years, age <65 years, BMI ≥30 kg/m (obese), BMI <30 kg/m (nonobese), male, and female. Secondary analyses were then performed to compare the agreement between LOR depth and DD with that between LOR depth and LFD within each patient subgroup. Intraclass correlation coefficient (ICC) and Bland-Altman plot were used to assess the agreement between DD or LFD and LOR depth. Data from 335 ESIs were analyzed, including 147 cervical ESIs and 188 lumbar ESIs. Estimated ICC values for the agreement between LOR depth and LFD for all lumbar and cervical measurements were 0.88 (95% confidence interval [CI], 0.85-0.91) and 0.72 (95% CI, 0.64-0.79), respectively. Estimated ICC values for the agreement between LOR depth and DD for all lumbar and cervical measurements were 0.86 (95% CI, 0.82-0.89) and 0.69 (95% CI, 0.60-0.77), respectively. This study assessed the agreement between MRI-derived measurements of epidural depth and those determined clinically. MRI-derived measurements from the skin to the anterior border of the ligamentum flavum, which represents the most posterior aspect of the epidural space, revealed stronger agreement with LOR depths than did measurements to the dura or the most anterior aspect of the epidural space. These results require further analysis and refinement before supporting clinical application.

Comparison of ocular biometric measurements between a new swept-source optical coherence tomography and a common optical low coherence reflectometry.

PubMed

Gao, Rongrong; Chen, Hao; Savini, Giacomo; Miao, Yaxin; Wang, Xiaorui; Yang, Jing; Zhao, Weiqi; Wang, Qinmei; Huang, Jinhai

2017-05-30

The purpose of the current study was to compare the measurements between a new optical biometer based on swept-source optical coherence tomography (SS-OCT), the OA-2000 (Tomey, Japan), and an optical biometer based on optical low coherence reflectometry (OLCR), the Lenstar (Haag-Streit, Switzerland). Ninety-nine eyes of 99 healthy subjects were included. The axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), aqueous depth (AD), lens thickness (LT), keratometry (K) readings, including flat K (Kf), steep K (Ks), mean K (Km), astigmatism vectors J 0 , J 45 at diameters of 2.5 and 3.0 mm, and white-to-white diameter (WTW) were measured three times each using both biometer in normal eyes by random sequence. Bland-Altman analysis showed good agreement between the SS-OCT and OLCR devices for AL, AD, ACD, LT, with narrow 95% LoA (-0.05 to 0.07 mm, -0.09 to 0.10 mm, -0.10 to 0.09 mm, and -0.06 to 0.22 mm, respectively), and the P values of ACD were both >0.05. The CCT, Kf, Ks, Km, J 0 , J 45 and WTW values provided by the OA-2000 were in good agreement with the Lenstar, and statistically significant differences were detected for some of them but not clinical differences. The agreement was excellent especially for AL.

Methylene blue-related corneal edema and iris discoloration.

PubMed

Timucin, Ozgur Bulent; Karadag, Mehmet Fatih; Aslanci, Mehmet Emin; Baykara, Mehmet

2016-04-01

We report the case of a 70-year-old female patient who developed corneal edema and iris discoloration following the inadvertent use of 1% methylene blue instead of 0.025% trypan blue to stain the anterior capsule during cataract phacoemulsification surgery. Copious irrigation was performed upon realization of incorrect dye use. Corneal edema and iris discoloration developed during the early postoperative period and persisted at 24-months follow-up. However, keratoplasty was not required. The intracameral use of 1% methylene blue has a cytotoxic effect on the corneal endothelium and iris epithelium. Copious irrigation for at least 30 min using an anterior chamber maintainer may improve outcomes.

Transthoracic ultrasonic tissue indices identify patients with severe left anterior descending artery stenosis. Correlation with fractional flow reserve. Pilot study.

PubMed

Dobrowolski, Piotr; Kowalski, Mirosław; Rybicka, Justyna; Lech, Agnieszka; Tyczyński, Paweł; Witkowski, Adam; Hoffman, Piotr

2016-01-01

The aim of this study was to evaluate the potential clinical application of ultrasonic tissue indices, with a focus on systolic strain (SS) and systolic strain rate (SSR) parameters derived from transthoracic echocardiography, in the assessment of left anterior descending artery (LAD) stenosis. The data of 30 patients with significant LAD stenosis were analysed. All patients underwent transthoracic echocardiography to obtain systolic myocardial velocity (Sm), longitudinal SS, and SSR from basal, mid, and apical segments of anterior and inferior walls in two-chamber apical view. Severity of LAD obstruction was measured by means of fractional flow reserve (FFR) during coronary catheterisation. Systolic velocities, strain, and strain rate measured in basal, middle, and apical segments of the anterior left ventricular (LV) wall were lower when compared to those obtained from the corresponding, i.e. unaffected, inferior LV wall. There was a significant correlation between FFR and the value of SS, SSR characterising the apical LV segment of the anterior wall (r = -0.583, p = 0.01; r = -0.598, p = 0.01, respectively). Moreover, we found significant correlation between FFR and Sm in the mid-segment of the LV anterior wall (r = 0.611, p = 0.009). We conclude that SS and SSR obtained from the apical segment of the anterior LV wall may be related to the severity of LAD stenosis.

Research on stability of nozzle-floating plate institution

NASA Astrophysics Data System (ADS)

Huang, Bin; Tao, Jiayue; Yi, Jiajing; Chen, Shijing

2016-01-01

In this paper, air hammer instability of nozzle-floating plate institution in gas lubricated force sensor were studied. Through establishment of the theoretical model for the analysis of the nozzle-floating plate institution stability, combined with air hammer stability judgment theorems, we had some simulation research on the radius of the nozzle, the radius of the pressure chamber, pressure chamber depth, orifice radius and the relationship between air supply pressure and bearing capacity, in order to explore the instability mechanism of nozzle-floating plate institution. For conducting experimental observations for the stability of two groups nozzle-floating plate institution, which have typical structural parameters conducted experimental observations. We set up a special experimental device, verify the correctness of the theoretical study and simulation results. This paper shows that in the nozzle-floating plate institution, increasing the nozzle diameter, reduced pressure chamber radius, reducing the depth of the pressure chamber and increase the supply orifice radius, and other measures is conducive to system stability. Results of this study have important implications for research and design of gas lubricated force sensor.

SU-E-T-665: Radiochromic Film Quenching Effect Reduction for Proton Beam Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aldelaijan, S; Alzorkany, F; Moftah, B

2015-06-15

Purpose: Depending on the useful dose range in which radiochromic films operate, number of different radiochromic film models have been designed. The impact of different film models on quenching effect for percent depth dose (PDD) measurements in proton beams has been investigated. Methods: Calibrated PTW Markus ionization chamber was used to measure PDD and beam output for 26.5 MeV protons produced by CS30 cyclotron. An aluminum cylinder was added in front of the beam exit serving as a radiation shutter. The measured signal was normalized to a monitor chamber reading and subsequently scaled by ratio of water-to-air stopping powers atmore » given depth, while the effective depth of measurements was scaled by ratios of material-to-water physical densities and CSDA ranges. Output was measured in water at 2.1 mm reference-depth in the plateau upstream from the Bragg peak. Following the TRS-398 reference dosimetry protocol for proton beams, the output was calibrated in water. Three radiochromic film models (EBT, EBT3 and HD-V2) were calibrated within Lexan phantom positioned at the same water-equivalent depth. Thicknesses of films sensitive layers were 34 µm, 30 µm and 8 µm, respectively. Small film pieces (1 x 2 cm{sup 2}) were positioned within polyethylene phantom along the beam central axis with an angulation of 5° for PDD measurements. Results: While the output of the proton beam was found to be around 7 Gy/sec, the actual value of the output per monitor chamber reading (2.32 Gy/nC) was used for reference-dose irradiations during film calibration. Dose ratios at the Bragg peak relative to the reference-depth were 3.88, 2.52, 2.19, and 2.02 for the Markus chamber, HD-V2, EBT3, and EBT film models, respectively. Conclusion: Results at hand suggest that quenching effect is reduced when a radiochromic film model with smaller sensitive layer thickness is used for PDD measurements in proton beams. David Lewis is the owner of RCF Consulting, LLC.« less

Corneal Stromal Elasticity and Viscoelasticity Assessed by Atomic Force Microscopy after Different Cross Linking Protocols

PubMed Central

Dias, Janice; Diakonis, Vasilios F.; Lorenzo, Michael; Gonzalez, Felipe; Porras, Kevin; Douglas, Simone; Avila, Marcel; Yoo, Sonia H.; Ziebarth, Noël M.

2015-01-01

The purpose of this study was to evaluate elasticity and viscoelasticity in the anterior and deeper stromal regions of the cornea after cross linking with three different protocols using atomic force microscopy (AFM) through indentation. A total of 40 porcine corneas were used in this study and were divided into 4 groups (10 corneas per group): control (no treatment), Dresden (corneal epithelial debridement, riboflavin pretreatment for 30 minutes and a 3mw/cm2 for 30 minutes UVA irradiation), accelerated (corneal epithelial debridement, riboflavin pretreatment for 30 minutes and a 30mw/cm2 for 3 minutes UVA irradiation), and genipin (corneal epithelial debridement and submersion of anterior surface in a 1% genipin solution for 4 hours). Elasticity and viscoelasticity were quantified using AFM through indentation for all corneas, for the anterior stroma and at a depth of 200μm. For the control, Dresden, accelerated, and Genipin groups, respectively, the average Young’s modulus for the anterior stromal region was 0.60±0.58MPa, 1.58 ±1.04MPa, 0.86±0.46MPa, and 1.71±0.51MPa; the average for the 200μm stromal depth was 0.08±0.06MPa, 0.08±0.04MPa, 0.08±0.04MPa, and 0.06±0.01MPa. Corneas crosslinked with the Dresden protocol and genipin were significantly stiffer than controls (p<0.05) in the anterior region only. For the control, Dresden, Accelerated, and Genipin groups, respectively, the average calculated apparent viscosity for the anterior stroma was 88.2±43.7kPa-s, 8.3±7.1kPa-s, 8.1±2.3kPa-s, and 9.5±3.8kPa-s; the average for the 200μm stromal depth was 35.0±3.7kPa-s, 49.6±35.1kPa-s, 42.4±17.6kPa-s, and 41.8±37.6kPa-s. All crosslinking protocols resulted in a decrease in viscosity in the anterior region only (p<0.05). The effects of cross-linking seem to be limited to the anterior corneal stroma and do not extend to the deeper stromal region. Additionally, the Dresden and genipin protocols seem to produce a stiffer anterior corneal stroma when compared to the accelerated protocol. PMID:26093276

Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 06: Investigation of an absorbed dose to water formalism for a miniature low-energy x-ray source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, Peter; Seuntjens, Jan

Purpose: We present a formalism for calculating the absorbed dose to water from a miniature x-ray source (The INTRABEAM system, Carl Zeiss), using a parallel-plate ionization chamber calibrated in terms of air-kerma. Monte Carlo calculations were performed to derive a chamber conversion factor (C{sub Q}) from reference air-kerma to dose to water for the INTRABEAM. C{sub Q} was investigated as a function of depth in water, and compared with the manufacturer’s reported value. The effect of chamber air cavity dimension tolerance was also investigated. Methods: Air-kerma (A{sub k}) from a reference beam was calculated using the EGSnrc user code cavity.more » Using egs-chamber, a model of a PTW 34013 parallel-plate ionization chamber was created according to manufacturer specifications. The dose to the chamber air cavity (D{sub gas}) was simulated both in-air (with reference beam) and in-water (with INTRABEAM source). Dose to a small water voxel (D{sub w}) was also calculated. C{sub Q} was derived from these quantities. Results: C{sub Q} was found to vary by up to 15% (1.30 vs 1.11) between chamber dimension extremes. The agreement between chamber C{sub Q} was found to improve with increasing depth in water. However, in all cases investigated, C{sub Q} was larger than the manufacturer reported value of 1.054. Conclusions: Our results show that cavity dimension tolerance has a significant effect on C{sub Q}, with differences as large as 15%. In all cases considered, C{sub Q} was found to be larger than the reported value of 1.054. This suggests that the recommended calculation underestimates the dose to water.« less

Highly Resolved Mg/Ca Depth Profiles of Planktic Foraminifer test Walls Using Single shot Measurements of fs-LA-ICPMS

NASA Astrophysics Data System (ADS)

Jochum, K. P.; Schiebel, R.; Stoll, B.; Weis, U.; Haug, G. H.

2017-12-01

Foraminifers are sensitive archives of changes in climate and marine environment. It has been shown that the Mg/Ca signal is a suitable proxy of seawater temperature, because the incorporation of Mg depends on ambient water temperature. In contrast to most former studies, where this ratio is determined by solution-based bulk analysis of 20 - 30 specimens, we have investigated Mg/Ca in single specimens and single chambers at high resolution. A new fs-200 nm-LA-ICPMS technique was developed for the µm-sized layered calcite shells. To generate depth profiles with a resolution of about 50 nm/shot, we chose a low fluence of about 0.3 Jcm-2 and performed single shot measurements of the double charged 44Ca++ and the single charged 25Mg+ ions together. Precision (RSD) of the Mg/Ca data is about 5 %. Calibration was performed with the carbonate reference material MACS-3 from the USGS. Our results for different species from the Arabian Sea and Caribbean Sea demonstrate that Mg/Ca of different chambers vary and indicate that the foraminifer individuals built their chambers in different water depths and/or experienced seasonal changes in seawater temperature caused, for example, by upwelling (cold) versus stratified (warm) conditions. Typically, the Mg/Ca ratios of the final two chambers of the planktic foraminifer Globorotalia menardii from a sediment core of the Arabian Sea differ by about 5 mmol/mol from earlier chambers (2 mmol/mol) corresponding to seawater temperatures of 28 °C and 18 °C, respectively. In addition, mass fractions of other elements like Sr, Mn, Fe, Ba, and U have been determined with fs-LA-ICPMS using fast line scans, and thus provide further insights in the ecology of foraminifers.

Morphological changes in the anterior segment of the Abyssinian cat eye with hereditary rod-cone degeneration.

PubMed

May, Chr Albrecht; Lütjen-Drecoll, Elke; Narfström, Kristina

2005-10-01

The purpose of this study was to investigate morphological changes of the anterior segment of the eye in Abyssinian cats with progressive rod-cone degeneration and to correlate them with blood flow data obtained in the same animals. Sections of the left eyes of six normal cats and of eight cats with different stages of hereditary retinal degeneration were prepared for transmission and scanning electron microscopy. Tangential and sagittal sections were also stained with antibodies against substance P, tyrosine hydroxylase, panneuronal marker PGP9.5, nitric oxide synthase, synaptophysin, and smooth muscle alpha-actin. In Abyssinian cats with hereditary rod-cone degeneration, significant changes were observed in the iris consisting of irregularities in the vascular wall of smaller arteries without changes in their innervation pattern. The ciliary processes were shorter than in normal cats, and their structure appeared more compact and retracted. Slight changes were also observed in the anterior part of the ciliary epithelium. The anterior chamber angle region did not appear to be affected. Clear morphological correlations to the physiological blood flow data were observed in the anterior eye segment, pointing not only to functional but also morphological vascular abnormalities in this animal model for retinitis pigmentosa.

On the detectability of Teide volcano magma chambers (Tenerife, Canary Islands) with magnetotelluric data

NASA Astrophysics Data System (ADS)

Piña-Varas, Perla; Ledo, Juanjo; Queralt, Pilar; Marcuello, Alex; Perez, Nemesio

2018-01-01

Tenerife has been the subject of numerous studies covering a wide range of fields. Many studies have been focused on characterising the magmatic plumbing system. Even so, a controversy still exists regarding the location and size of the current magma chambers. Several magnetotelluric (MT) surveys have been carried out in the island, but no conductivity anomalies associated with the chambers have been detected. We report the results of a set of tests conducted against the 3-D resistivity model of the island, to determine the characteristics of the detectable chambers with the MT data. The most remarkable results indicate that the MT dataset is incompatible with a large-scale mafic reservoir located at shallower depths than 8 km b.s.l. However, shallower phonolitic chambers smaller than 3 × 3 × 1 km3 could be undetected by the existing MT sites and new data should be acquired to confirm or not their existence. This new information is essential in volcanic islands like Tenerife, since many volcanic hazards are related to the size and depth of the sources of magma. Additionally, a joint interpretation of the obtained results together with other information is summarised in a hypothetical model, allowing us to better understand the internal structure of the island.[Figure not available: see fulltext.

Novel Molecular Imaging Approach for Subclinical Detection of Iritis and Evaluation of Therapeutic Success

PubMed Central

Xie, Fang; Sun, Dawei; Schering, Alexander; Nakao, Shintaro; Zandi, Souska; Liu, Ping; Hafezi-Moghadam, Ali

2010-01-01

There is an urgent need for early diagnosis in medicine, whereupon effective treatments could prevent irreversible tissue damage. Acute anterior chamber inflammation is the most common form of uveitis and a major cause of vision loss. The proximity of the iris vasculature to the light-permeable cornea and its involvement in ocular inflammation make it an ideal target for noninvasive molecular imaging. To accomplish this, carboxylated fluorescent microspheres (MSs) were conjugated with recombinant P-selectin glycoprotein ligand-1 and systemically injected in endotoxin-induced uveitic animals. MS adhesion in the microcirculation of the anterior and posterior chamber was visualized by intravital microscopy and scanning laser ophthalmoscopy. In iritic animals, significantly higher numbers of recombinant P-selectin glycoprotein ligand-1-conjugated MSs adhered to the endothelium (P = 0.03) matching the increase in leukocyte adhesion. Conjugated MSs specifically interacted with firmly adhering leukocytes, allowing quantification of the endogenous immune response. Topical eye drop treatment with dexamethasone (P < 0.01) or cyclosporine A (P < 0.01) significantly lowered MS adhesion in iris vessels. Surprisingly, topical dexamethasone significantly reduced MS interaction in the fundus vessels (P < 0.01), while cyclosporine A did not. In vivo MS accumulation preceded clinical signs of anterior uveitis and leukocyte adhesion in iris vasculature. This work introduces noninvasive subclinical detection of endothelial injury in the iris vasculature, providing a unique opportunity for quantifying vascular injury and immune response in vivo. PMID:20581051

Sildenafil Stimulates Aqueous Humor Turnover in Rabbits

PubMed Central

Alvarez, Lawrence J.; Zamudio, Aldo C.; Candia, Oscar A.

2013-01-01

Sildenafil citrate increases ocular blood flow and accelerates the rate of anterior chamber refilling after paracentesis. The latter effect could have resulted from a reduction in outflow facility or from an increase in aqueous humor (AH) production. In this study, we used scanning ocular fluorophotometry to examine the effects of sildenafil on AH turnover, and thus, AH production in eyes of live normal rabbits. For this, the rate of aqueous humor flow (AHF) was quantified with a commercially available fluorophotometer that measured the rate of fluorescein clearance from the anterior segment, which predominantly occurs via the trabecular meshwork. After ≈ 2 hrs of control scans to determine the baseline rate of AHF, the rabbits were fed 33 mg of sildenafil and allowed ≈ 45 min for the drug to enter the systemic circulation. Thereafter, fluorescence scans were retaken for an additional 90–120 min. Sildenafil ingestion increased AHF by about 36%, from 2.31 μL/min to 3.14 μL/min (P< 0.001, as two-tailed paired data, n= 20 eyes). This observation indicates that sildenafil citrate, which is a phosphodiesterase type-5 inhibitor currently marketed as a vasodilator (e.g., Viagra, Revatio), stimulates AHF in rabbits. Our results seem consistent with reports indicating that the drug dilates intraocular arteries and augments intraocular vascular flow. These physiological responses to the agent apparently led to increased fluid entry into the anterior chamber. As such, the drug might have utility in patients with ocular hypotony resulting from insufficient AH formation. PMID:23562660

Progress Towards a Thermo-Mechanical Magma Chamber Forward Model for Eruption Cycles, Applied to the Columbia River Flood Basalts

NASA Astrophysics Data System (ADS)

Karlstrom, L.; Ozimek, C.

2016-12-01

Magma chamber modeling has advanced to the stage where it is now possible to develop self-consistent, predictive models that consider mechanical, thermal, and compositional magma time evolution through multiple eruptive cycles. We have developed such a thermo-mechanical-chemical model for a laterally extensive sill-like chamber beneath free surface, to understand physical controls on eruptive products through time at long-lived magmatic centers. This model predicts the relative importance of recharge, eruption, assimilation and fractional crystallization (REAFC, Lee et al., 2013) on evolving chemical composition as a function of mechanical magma chamber stability regimes. We solve for the time evolution of chamber pressure, temperature, gas volume fraction, volume, elemental concentration in the melt and crustal temperature field that accounts for moving boundary conditions associated with chamber inflation (and the possibility of coupled chambers at different depths). The density, volume fractions of melt and crystals, crustal assimilation and the changing viscosity and crustal properties of the wall rock are also tracked, along with joint solubility of water and CO2. The eventual goal is to develop an efficient forward model to invert for eruptive records at long-lived eruptive centers, where multiple types of data for eruptions are available. As a first step, we apply this model to a new compilation of eruptive data from the Columbia River Flood Basalts (CRFB), which erupted 210,000 km3 from feeder dikes in Washington, Oregon and Idaho between 16.9-6Ma. Data include volumes, timing and geochemical composition of eruptive units, along with seismic surveys and clinopyroxene geobarometry that constrain depth of storage through time. We are in the process of performing a suite of simulations varying model input parameters such as mantle melt rate, emplacement depth, wall rock compositions and rheology, and volatile content to explain volume, eruption timescales, and chemical trace aspects of CRFB eruptions. We are particularly interested in whether the large volume eruptions of the main phase Grande Ronde basalts were made possible due to the development of shallow crustal storage.

Intraocular gnathostomiasis from coastal part of Maharashtra

PubMed Central

Sujata, Dharmshale N; Renu, Bharadwaj S

2013-01-01

Intraocular infestation by live Gnathostoma spinigerum is a rare occurrence in humans. Most of the published reports are from South-East Asia. We report a case of ocular gnathostomiasis from Western Maharashtra, where the worm was removed live from the anterior chamber of the left eye. Identification of the worm was confirmed by light microscopy. PMID:23961449

[Moxiflaxin and iris transillumination].

PubMed

Broens, A; Collignon, N

2016-07-01

Bilateral Acute Iris Transillumination (BAIT) is a new clinical entity characterized by acute onset of pigment dispersion in the anterior chamber and angle, depigmentation of the iris stroma and permanent iris transillumination, masquerading as uveitis. An association with oral moxifloxacin is reported in some articles. We describe one case of bilateral acute iris transillumination, following the use of systemic moxifloxacin.

Keratotorus in Norrie disease.

PubMed

Lang, G E; Rott, H D; Naumann, G O

1991-08-01

We report on a 46-year old white male with Norrie disease. In the right eye he had a keratotorus with non vascularized corneal scars and mature cataract. After penetrating keratoplasty a pseudoglioma with irreversible total retinal detachment was found. The left eye had phthisis bulbi with corneal pannus and band keratopathy, shallow anterior chamber, posterior synechia and mature cataract.

Slit-lamp Needling of the Anterior Capsule for Aqueous Misdirection After Hyaloido-zonulectomy and Iridectomy.

PubMed

Mardelli, Pierre G; Mardelli, Marc E

2018-04-01

We present a case of persistent aqueous misdirection, after Ahmed glaucoma valve surgery, despite undergoing an anterior vitrectomy with hyaloido-zonulectomy and iridectomy. A 73-year-old female patient, 4 months after phacotrabeculectomy, was referred with persistent high intraocular pressure (IOP). Postoperatively, she developed aqueous misdirection with a flat anterior chamber (AC) but with an IOP of 15 mm Hg. On presentation, her AC was shallow with peripheral iris-cornea touch, and her IOP was 39 mm Hg. Posterior Nd:Yag capsulotomy with disruption of anterior hyaloid face partially deepened the AC. With failure of the trabeculectomy and high IOP, an Ahmed valve was placed. On the first operative day the AC was deep with an IOP of 10 mm Hg. On day 6 the patient presented with pain, flat AC, and an IOP of 10 mm Hg. Fundus examination revealed no choroidal effusion. Despite repeated reformation with viscoelastic, the AC failed to deepen. An anterior vitrectomy with hyaloido-zonulectomy was performed. Initially, the AC was deep, but, a few days later, it was flat. Multiple reformations and vitreous tap failed to keep the AC deep. A 30-G needle was passed at the slit lamp across the temporal cornea, iris, and anterior capsule into the anterior vitreous cavity. The needle was then partially withdrawn and used to create a space between the intraocular lens and anterior capsule. This immediately deepened the AC and remained so for the duration of follow-up (4 mo). Slit-lamp needling of the anterior lens capsule can be successfully performed to help resolve a persistent case of aqueous misdirection after anterior vitrectomy.