[Effect of double anaesthetic Colicursi (tetracaine 0.1% and oxybuprocaine 0.4%) on central and paracentral corneal thickness].

PubMed

Díaz-Rey, J A; Giráldez, M J; García-Resúa, C; Yebra-Pimentel, E

2009-01-01

To study the effect of 1 drop of combined topical anaesthesia (tetracaine 0.1% and oxybuprocaine 0.4%) on central corneal thickness (CCT) values and at 2.5 mm from the corneal centre in nasal, temporal, superior and inferior hemi meridians, monitored by Orbscan over a period of 16 minutes. The corneal thickness of 12 right eyes of 12 young healthy men was determined using the Orbscan Topography System. Values were determined at the centre and paracentral regions 2.5 mm from the centre every 2 minutes for 16 minutes before and after the administration of 1 drop of double anaesthetic Colircusi which contains tetracaine 0.1% and oxybuprocaine 0.4%. There was no obvious trend of central and paracentral corneal thickness value change before and after administration of Colircusi (paired ANOVA, p>0.05). Although corneal thickness variation was not statistically significant, higher differences were observed at the 6 minute time-point for CCT and at 8 minutes for nasal paracentral corneal thickness. One drop of double anaesthetic Colircusi with tetracaine 0.1% and oxibuprocaine 0.4% does not produce any significant change in central corneal thickness or in paracentral regions 2.5 mm from the centre (nasal, temporal, superior and inferior hemi meridians).

The Effect of Ocular Surface Regularity on Contrast Sensitivity and Straylight in Dry Eye.

PubMed

Koh, Shizuka; Maeda, Naoyuki; Ikeda, Chikako; Asonuma, Sanae; Ogawa, Mai; Hiraoka, Takahiro; Oshika, Tetsuro; Nishida, Kohji

2017-05-01

To investigate the association between visual function and ocular surface regularity in dry eye. We enrolled 52 eyes of 52 dry eye patients (34 dry eyes with superficial punctate keratopathy [SPK] in the central corneal region [central SPK] and 18 dry eyes without central SPK) and 20 eyes of 20 normal control subjects. All eyes had a best-corrected distance visual acuity better than 20/20. We measured two indices of contrast sensitivity function under photopic conditions: contrast sensitivity and letter contrast sensitivity. The area under the log contrast sensitivity function (AULCSF) was calculated from the obtained contrast sensitivity data. Straylight was quantified using a straylight meter. Dry eyes with central SPK had significantly decreased contrast sensitivity function, including AULCSF and letter contrast sensitivity than those without central SPK and normal eyes (P < 0.05 for each). While the straylight values in both dry eye groups did not differ, straylight values were greater than those in normal eyes (P < 0.05 for both). In dry eye, the AULCSF and letter contrast sensitivity negatively correlated with the central SPK score (R = -0.485, P < 0.001, and R = -0.541, P < 0.001, respectively). In dry eye, reduced contrast sensitivity in part results from central SPK overlying the optical zone and the increased straylight results from tear film instability rather than central SPK.

Corneal subbasal nerve fiber regeneration in myopic patients after laser in situ keratomileusis★

PubMed Central

Deng, Shijing; Wang, Mengmeng; Zhang, Fengju; Sun, Xuguang; Hou, Wenbo; Guo, Ning

2012-01-01

A total of 26 myopic patients (52 eyes) underwent laser in situ keratomileusis. In vivo confocal microscopy revealed that most of the regenerated corneal subbasal nerve fibers in the corneal flap originated from the stump of corneal subbasal nerve fibers outside the ablation zone and extended towards the center of the cornea in all patients. Meanwhile, new fibers were also found to directly regenerate from deep in the stroma in some cases. Approximately 94% of regenerated corneal subbasal nerve fibers (73/78 eyes) regrew vertically into the peripheral central 6-mm circle area 1 month after surgery, 78% (28/36 eyes) grew into the central 3–6 mm area at 2 months, and 23% into the central 3-mm circle area at 3 months. In addition, there was no significant difference in corneal subbasal nerve fiber regenerative capacity between the basic fibroblast growth factor group and the 20% (v/v) deproteinized extract of calf blood group. The majority of corneal subbasal nerve fiber regeneration occurred from the stump of corneal subbasal nerve fibers outside the corneal flap, and the remaining growth occurred deep within the stroma. PMID:25657693

Epifluorescence Intravital Microscopy of Murine Corneal Dendritic Cells

PubMed Central

Rosenbaum, James T.; Planck, Stephen R.

2010-01-01

Purpose. Dendritic cells (DCs) are antigen-presenting cells vital for initiating immune responses. In this study the authors examined the in vivo migratory capability of resident corneal DCs to various stimuli. Methods. The authors used mice expressing enhanced yellow fluorescent protein (eYFP) under control of the CD11c promoter to visualize corneal DCs. To assess the distribution and mobility of DCs, normal corneas were imaged in vivo and ex vivo with fluorescence microscopy. Intravital microscopy was used to examine the responses of resident central and peripheral corneal DCs to silver nitrate injury, lipopolysaccharide, microspheres, and tumor necrosis factor (TNF-α). In some experiments, TNF-α injection was used to first induce centripetal migration of DCs to the central cornea, which was subsequently reinjected with microspheres. Results. In normal corneas, DCs were sparsely distributed centrally and were denser in the periphery, with epithelial-level DCs extending into the epithelium. Videomicroscopy showed that though cell processes were in continuous movement, cells generally did not migrate. Within the first 6 hours after stimulation, neither central nor peripheral corneal DCs exhibited significant lateral migration, but central corneal DCs assumed extreme morphologic changes. An increased number of DCs in the TNF-α–stimulated central cornea were responsive to subsequent microsphere injection by adopting a migratory behavior, but not with increased speed. Conclusions. In vivo imaging reveals minimal lateral migration of corneal DCs after various stimuli. In contrast, DCs within the central cornea after initial TNF-α injection are more likely to respond to a secondary insult with lateral migration. PMID:20007837

[How does central cornea thickness influence intraocular pressure during applanation and contour tonometry?].

PubMed

Schwenteck, T; Knappe, M; Moros, I

2012-09-01

Golmann applanation tonometry represents a well-established procedure for measuring intraocular pressure (IOP). This implies the necessity of an accurate measurement of IOP with the reference tonometer. One example is the contour tonometer Pascal with a measuring probe, adapted to the cornea geometry, for measuring the IOP and the ocular pulse amplitude. There is controversy of how strongly corneal thickness affects the measurement of IOP. We thus analysed, for a number of eyes, the correlation of IOP, as measured by two types of applanation tonometers and one contour tonometer and the central corneal thickness. In all 158 patient eyes were investigated in a clinical comparison of applanation tonometers AT 870 and Ocuton-A. The study was performed by a trained ophthalmologist and the comparison was in accordance with international standard ISO 8612. In addition, the corneal thickness in the vertex was repeatedly determined using an Oculus Pentacam. The potential effect of central corneal thickness on the IOP as measured by the mentioned tonometers was statistically evaluated by rank correlation analysis. We found that the measured IOP values for the three investigated tonometers were not normally distributed. The central corneal thickness values, in contrast, measured on 158 eyes by means of an ultrasound pachymeter and additionally on 235 eyes by the Pentacam, obeyed a Gaussian distribution. For the correlation analysis of both parameters the Spearman linear rank correlation coefficient (r) was considered. We found a very weak (|r| < 0.2) correlation between central corneal thickness and IOP for all 3 tonometers. The softness of the correlation is also illustrated by a large standard deviation of the regression line. A comparison of the different devices for corneal-thickness measurements shows less variance and a smaller variation coefficient when the ultrasoundpachymeter AL-1000 is used. The measured values for IOP are only very weakly correlated to the central corneal thickness. For the 3 tonometer types studied there is no need to correct the indicated pressure values according to the central corneal thickness of the investigated eye. Clinical comparisons according to the ISO 8612 standard between a tonometer under test and a reference Goldmann applanation tonometer are always a time-consuming procedure. Additional measures to determine the central corneal thickness of every investigated eyes are dispensable. © Georg Thieme Verlag KG Stuttgart · New York.

Relationship between central and peripheral corneal astigmatism in elderly patients

NASA Astrophysics Data System (ADS)

Kawamorita, Takushi; Shimizu, Kimiya; Hoshikawa, Rie; Kamiya, Kazutaka; Shoji, Nobuyuki

2018-03-01

Abstract Purpose We investigated the relationship between central and peripheral corneal astigmatism in elderly patients. Methods Seventy-six eyes of 76 elderly subjects (mean age = 72.6 ± 3.0 years) were included in the study. Corneal shape was evaluated using the Pentacam HR (Oculus, Wetzlark, Germany), which is comprised of a rotating Scheimpflug camera and a short-wavelength slit light. The power distribution map was selected and corneal astigmatism was calculated using front K-Readings in zones centered on the pupil. Analyzed zones were 2.0-6.0 mm in diameter. Results Corneal astigmatism decreased as diameter increased, similar to what was observed in eyes with with-the-rule astigmatism and against-the-rule astigmatism (ANOVA, p < 0.01). This effect was more pronounced in eyes with a large central corneal astigmatism (Spearman's rank-correlation coefficient test, r = 0.51, p < 0.01). There was no change as to axis of corneal astigmatism (ANOVA, p = 0.98). Conclusion These results suggest that the relationship between central and peripheral corneal astigmatism should be taken into consideration to optimize vision when astigmatic correction is needed.

The relationship between corneal biomechanics and anterior segment parameters in the early stage of orthokeratology: A pilot study.

PubMed

Chen, Renai; Mao, Xinjie; Jiang, Jun; Shen, Meixiao; Lian, Yan; Zhang, Bin; Lu, Fan

2017-05-01

To investigate the relationship between corneal biomechanics and anterior segment parameters in the early stage of overnight orthokeratology.Twenty-three eyes from 23 subjects were involved in the study. Corneal biomechanics, including corneal hysteresis (CH) and corneal resistance factor (CRF), and parameters of the anterior segment, including corneal curvature, central corneal thickness (CCT), and corneal sublayers' thickness, were measured at baseline and day 1 and 7 after wearing orthokeratology lens. One-way analysis of variance with repeated measures was used to compare the longitudinal changes and partial least squares linear regression was used to explore the relationship between corneal biomechanics and anterior segment parameters.At baseline, CH and CRF were positively correlated with CCT (r = 0.244, P = .008 for CH; r = 0.249, P < .001 for CRF), central stroma thickness (CST) (r = 0.241, P = .008 for CH; r = 0.244, P = .002 for CRF) and central Bowman layer thickness (CBT) (r = 0.138, P = .039 for CH; r = 0.171, P = .006 for CRF). Both CH and CRF significantly decreased from day 1 after orthokeratology. The corneal curvature and the epithelium thickness also significantly decreased, while the stromal layer thickened significantly from day 1 after orthokeratology. There was no correlation between the changes of corneal biomechanics and anterior segment parameters at day 1 and 7 after orthokeratology.While corneal biomechanics were positively correlated with CCT, CST, and CBT, the changes of CH and CRF were not correlated with the changes of corneal curvature, CCT, and corneal sublayers' thickness in the early stage of orthokeratology in our study.

A case report of central toxic keratopathy in a patient post TransPRK (followed by corneal collagen cross-linking)

PubMed Central

Davey, Nicholas; Aslanides, Ioannis M; Selimis, Vasilis

2017-01-01

Purpose The purpose of this article is to report a case of central toxic keratopathy in a patient post transepithelial photorefractive keratectomy (TransPRK), followed immediately by corneal collagen cross-linking. Methods This article describes the case of a 26-year-old male after bilateral aberration-free, TransPRK laser (Schwind Amaris 750S). The procedure was performed for compound myopic astigmatism in November 2015, followed immediately by accelerated corneal collagen cross-linking for early keratoconus. Results From day 3 post-op, tear film debris underneath both contact lenses with corneal haze and early, progressive central anterior stromal opacity formation only in the left eye were noted. At 2 weeks post-op, the left eye was noted to have a significant hyperopic shift with central corneal thinning in the anterior stroma. A central anterior stromal dense opacity had formed in the left eye with the surrounding superficial stromal haze. As of month 2, the opacity gradually started to improve in size and density. The hyperopic shift peaked at 2 months and continued to improve, largely due to epithelial compensation with a gradual recovery of stromal thickness. Conclusion The question remains as to what provokes the typical central corneal necrosis/thinning in central toxic keratopathy. We hypothesize that the space between the contact lens and the corneal surface post TransPRK is prone to a “pseudo-interface pathology” that could mimic diffuse lamellar keratitis-like pathology. Suboptimal lid hygiene, resulting in tear film combinations of bacteria, inflammatory cells, matrix metalloproteinases and other proteolytic enzymes, contributes to the degradation of vulnerable, exposed collagen stromal tissue post TransPRK or any surface corneal ablation. Refractive surgeons should maintain a healthy lid margin and tear film, especially in contact lens wearers, to prevent potential complications in refractive surgery procedures. PMID:28450791

Investigation on fibrous collagen modifications during corneal laser welding by second harmonic generation microscopy

NASA Astrophysics Data System (ADS)

Matteini, Paolo; Ratto, Fulvio; Rossi, Francesca; Cicchi, Riccardo; Stringari, Chiara; Kapsokalyvas, Dimitrios; Pavone, Francesco S.; Pini, Roberto

2009-02-01

The structural modifications in the collagen lattice of corneal stroma induced by near-infrared laser welding were investigated with second-harmonic generation (SHG) imaging. The corneal laser welding procedure is performed by staining the wound edges with a saturated water solution of Indocyanine Green (ICG) followed by irradiation with a 810 nm diode laser operated in continuous (CWLW: continuous wave laser welding) or pulsed (PLW: pulsed laser welding) mode. Both these procedures can provide closure of corneal wounds by inducing different structural modifications in the extracellular matrix. SHG imaging of native corneal stroma revealed collagen bundles composed of many regularly aligned collagen fibrils. After CWLW the regular lamellar arrangement was lost; collagen bundles appeared densely packed with an increasing disordered arrangement toward the welded cut. The weld was characterized by a loss of details; nevertheless, the observation of the second harmonic signal at this site indicated the lack of collagen denaturation. By contrast, PLW mode produced welding spots at the interface between donor and recipient corneal layers, which were characterized by a severe loss of the SHG signal, suggesting the occurrence of a complete collagen denaturation. SHG imaging appeared to be a powerful tool for visualizing the supramolecular morphological modifications in the collagen matrix after laser welding.

Excimer laser phototherapeutic keratectomy for shield ulcers and corneal plaques in vernal keratoconjunctivitis.

PubMed

Cameron, J A; Antonios, S R; Badr, I A

1995-01-01

Shield-shaped corneal ulcers and corneal plaques in vernal keratoconjunctivitis are associated with delayed epithelial healing, as well as the risks of infectious keratitis and sterile stromal ulceration. Significant visual impairment due to scarring and irregular astigmatism may result from central corneal lesions. Three eyes with central corneal lesions resulting from vernal keratoconjunctivitis were treated by excimer laser after active vernal keratoconjunctivitis was controlled and inflammatory plaque overlying the shield ulcers was removed. All three eyes showed rapid reepithelialization within 1 week. Spectacle-corrected visual acuity of 20/30 or better was obtained in each eye. In selected patients, excimer laser phototherapeutic keratectomy may be a useful adjunct in the treatment of shield-shaped corneal ulcers and plaques in vernal keratoconjunctivitis.

[Recent studies on corneal epithelial barrier function].

PubMed

Liu, F F; Li, W; Liu, Z G; Chen, W S

2016-08-01

Corneal epithelium, the outermost layer of eyeball, is the main route for foreign materials to enter the eye. Under physiological conditions, the corneal epithelial superficial cells form a functionally selective permeability barrier. Integral corneal epithelial barrier function not only ensures the enrolling of nutrients which is required for regular metabolism, but also prevents foreign bodies, or disease-causing microorganism invasion. Recently, a large number of clinical and experimental studies have shown that abnormal corneal epithelial barrier function is the pathological basis for many ocular diseases. In addition, some study found that corneal epithelial barrier constitutes a variety of proteins involved in cell proliferation, differentiation, apoptosis, and a series of physiological and pathological processes. This paper reviewed recent studies specifically on the corneal epithelial barrier, highlights of its structure, function and influence factors. (Chin J Ophthalmol, 2016, 52: 631-635).

Ocular dimensions, corneal thickness, and corneal curvature in quarter horses with hereditary equine regional dermal asthenia.

PubMed

Badial, Peres R; Cisneros-Àlvarez, Luis Emiliano; Brandão, Cláudia Valéria S; Ranzani, José Joaquim T; Tomaz, Mayana A R V; Machado, Vania M; Borges, Alexandre S

2015-09-01

The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Five HERDA-affected quarter horses and five healthy control quarter horses were used. Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature. Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions. Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA. © 2014 American College of Veterinary Ophthalmologists.

Comparison of Central Corneal Thickness Between Fourier-Domain OCT, Very High-Frequency Digital Ultrasound, and Scheimpflug Imaging Systems.

PubMed

Yap, Timothy E; Archer, Timothy J; Gobbe, Marine; Reinstein, Dan Z

2016-02-01

To compare corneal thickness measurements between three imaging systems. In this retrospective study of 81 virgin and 58 post-laser refractive surgery corneas, central and minimum corneal thickness were measured using optical coherence tomography (OCT), very high-frequency digital ultrasound (VHF digital ultrasound), and a Scheimpflug imaging system. Agreement between methods was analyzed using mean differences (bias) (OCT - VHF digital ultrasound, OCT - Scheimpflug, VHF digital ultrasound - Scheimpflug) and Bland-Altman analysis with 95% limits of agreement (LoA). Virgin cornea mean central corneal thickness was 508.3 ± 33.2 µm (range: 434 to 588 µm) for OCT, 512.7 ± 32.2 µm (range: 440 to 587 µm) for VHF digital ultrasound, and 530.2 ± 32.6 µm (range: 463 to 612 µm) for Scheimpflug imaging. OCT and VHF digital ultrasound showed the closest agreement with a bias of -4.37 µm, 95% LoA ±12.6 µm. Least agreement was between OCT and Scheimpflug imaging with a bias of -21.9 µm, 95% LoA ±20.7 µm. Bias between VHF digital ultrasound and Scheimpflug imaging was -17.5 µm, 95% LoA ±19.0 µm. In post-laser refractive surgery corneas, mean central corneal thickness was 417.9 ± 47.1 µm (range: 342 to 557 µm) for OCT, 426.3 ± 47.1 µm (range: 363 to 563 µm) for VHF digital ultrasound, and 437.0 ± 48.5 µm (range: 359 to 571 µm) for Scheimpflug imaging. Closest agreement was between OCT and VHF digital ultrasound with a bias of -8.45 µm, 95% LoA ±13.2 µm. Least agreement was between OCT and Scheimpflug imaging with a bias of -19.2 µm, 95% LoA ±19.2 µm. Bias between VHF digital ultrasound and Scheimpflug imaging was -10.7 µm, 95% LoA ±20.0 µm. No relationship was observed between difference in central corneal thickness measurements and mean central corneal thickness. Results were similar for minimum corneal thickness. Central and minimum corneal thickness was measured thinnest by OCT and thickest by Scheimpflug imaging in both groups. A clinically significant bias existed between Scheimpflug imaging and the other two modalities. Copyright 2016, SLACK Incorporated.

Which soft contact lens power is better for piggyback fitting in keratoconus?

PubMed

Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; Flores-Rodríguez, Patricia; González-Méijome, Jose Manuel

2013-02-01

To evaluate the impact of differente soft contact lens power in the anterior corneal curvature and regularity in subjects with keratoconus. Nineteen subjects (30 eyes) with keratoconus were included in the study. Six corneal topographies were taken with Pentacam Eye System over the naked eye and successively with soft lens (Senofilcon A) powers of -3.00, -1.50, 0.00, +1.50 and +3.00 D. Corneal measurements of mean central keratometry (MCK), maximum tangential curvature (TK), maximum front elevation (MFE) and eccentricity (Ecc) at 6 and 8 mm diameters as well as anterior corneal surface high order aberrations (i.e. total RMS, spherical- and coma-like and secondary astigmatism) were evaluated. Negative- and plano-powered soft lenses flattened (p<0.05 in all cases), whereas positive-powered lenses did not induce any significant changes (p>0.05 in all cases) in MCK in comparison to the naked eye. The TK power decreased with negative lenses (p<0.05 in both cases) and increased with +3.00 D lenses (p=0.03) in comparison to the naked eye. No statistically significant differences were found in MFE with any soft lens power in comparison to the naked eye (p>0.05 in all cases). Corneal eccentricity increased at 8 mm diameter for all lens powers (p<0.05 in all cases). No statistically differences were found in HOA RMS and spherical-like aberration (both p>0.05). Statistically differences were found in coma-like and secondary astigmatism (both p<0.05). Negative-powered soft contact lenses provide a flatter anterior surface in comparison to positive-powered lenses in subjects with keratoconus and thus they might be more suitable for piggyback contact lens fitting. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Dry eye evaluation and correlation analysis between tear film stability and corneal surface regularity after small incision lenticule extraction.

PubMed

Zhang, Hui; Wang, Yan

2017-09-22

To investigate the dry eye after small incision lenticule extraction (SMILE) and explore the correlations between changes in the tear film stability, the tear secretion and the corneal surface regularity. Sixty-two eyes of 22 men and 13 women who underwent SMILE were included in this study. Corneal topography was measured to assess the index of surface variance (ISV) and the index of vertical asymmetry (IVA). Dry eye tests including subjective symptom questionnaire, tear breakup time (TBUT), corneal fluorescein staining and Schirmer's test (ST) were evaluated before and at 1 and 6 months postoperatively. TBUT was found to be significantly decreased from 9.8 ± 3.4 s preoperatively to 7.4 ± 3.8 s at 1 month and 6.5 ± 3.6 s at 6 months (both P < 0.001). There was a significant decrease in ST at 1 month postoperatively (P = 0.012); however, ST returned to baseline by 6 months (P = 0.522). Both ISV and IVA significantly increased after the surgery (all P < 0.001). In addition, the changes in TBUT were negatively correlated with the increases in ISV and IVA (r = -0.343, P = 0.006 and r = -0.311, P = 0.014, respectively). Patients undergoing SMILE might develop a short-TBUT type of dry eye. Corneal surface regularity indices might be helpful in the assessment of tear film stability following SMILE procedure.

Changes in corneal biometry and the associated histology in rhesus monkeys wearing orthokeratology contact lenses.

PubMed

Ding, Hui; Pu, Aijun; He, Hong; Xie, Ruo Zhong; Yang, Jun; Liao, Aiping; Gao, Shaohui; Zhong, Xingwu

2012-08-01

This study compared the effect of orthokeratology (OK) lens wear on corneal topography and microstructure between the 1-night and 30-night wearers to predict any adverse responses of the eyes to long-term OK lens wear. Nine rhesus monkeys with one eye wearing an OK lens and the fellow eye wearing a rigid gas permeable (RGP) lens were used in this study. The lenses were worn for 11 hours, with the measurement of corneal curvature and thickness and axial components of the eye at 0 night (n = 9), 1 night (n = 9), and 30 nights (n = 6). Histology was performed at 1 and 30 nights of lens wear. Corneal surface power in the 3-mm central region was reduced in the OK eye when compared with the RGP eye (P < 0.05). Central corneal thickness was only reduced in 30 nights of OK lens wear (P < 0.05). Under light microscopy, the 1-night OK or RGP eyes showed normal morphology in all layers of the cornea. The 30-night OK eyes showed a thinned central corneal epithelium and a thickened but less stratified paracentral corneal epithelium when compared with the 30-night RGP eyes. Under electron microscopy, intercellular junctions of corneal epithelium in the 30-night OK eyes were much looser than those in the 1-night OK eyes. However, the density and morphology of hemidesmosomes were similar between the OK and RGP eyes at 30 nights of lens wear. Overnight OK can change the corneal curvature through anterior corneal remodeling, resulting in an effective correction of myopia. However, a decrease in intercellular junctions during long-term wear may compromise the functions of the corneal epithelium as a border mechanical barrier.

Surgical therapies for corneal perforations: 10 years of cases in a tertiary referral hospital

PubMed Central

Yokogawa, Hideaki; Kobayashi, Akira; Yamazaki, Natsuko; Masaki, Toshinori; Sugiyama, Kazuhisa

2014-01-01

Purpose To report surgical therapies for corneal perforations in a tertiary referral hospital. Methods Thirty-one eyes of 31 patients (aged 62.4±18.3 years) with surgically treated corneal perforations from January 2002 to July 2013 were included in this study. Demographic data such as cause of corneal perforation, surgical procedures, and visual outcomes were retrospectively analyzed. Results The causes of corneal perforation (n=31) were divided into infectious (n=8, 26%) and noninfectious (n=23, 74%) categories. Infectious causes included fungal ulcer, herpetic stromal necrotizing keratitis, and bacterial ulcer. The causes of noninfectious keratopathy included corneal melting after removal of a metal foreign body, severe dry eye, lagophthalmos, canaliculitis, the oral anticancer drug S-1, keratoconus, rheumatoid arthritis, neurotrophic ulcer, atopic keratoconjunctivitis, and unknown causes. Initial surgical procedures included central large corneal graft (n=17), small corneal graft (n=7), and amniotic membrane transplantation (n=7). In two cases the perforation could not be sealed during the first surgical treatment and required subsequent procedures. All infectious keratitis required central large penetrating keratoplasty to obtain anatomical cure. In contrast, several surgical options were used for the treatment of noninfectious keratitis. After surgical treatment, anatomical cure was obtained in all cases. Mean postoperative best corrected visual acuity was better at 6 months (logMAR 1.3) than preoperatively (logMAR 1.8). Conclusion Surgical therapies for corneal perforations in our hospital included central large lamellar/penetrating keratoplasty, small peripheral patch graft, and amniotic membrane transplantation. All treatments were effective. Corneal perforation due to the oral anticancer drug S-1 is newly reported. PMID:25378903

Correlation of central and peripheral corneal thickness in healthy corneas.

PubMed

Fares, Usama; Otri, Ahmad Muneer; Al-Aqaba, Mouhamed Ali; Dua, Harminder S

2012-02-01

To study the thickness profile of the normal cornea in order to establish any correlation between central and peripheral points. Sixty-seven eyes of 40 patients were subjected to central corneal thickness measurement (CCT) with an ultrasound pachymeter (UP) and corneal thickness mapping with the Oculus Pentacam. The corneal apex thickness (CAT), pupil centre thickness (recorded as CCT and corresponded to CCT of UP) and thickness at the thinnest location (CTL) were obtained and compared with each other. Corneal thickness data at 3 mm and 7 mm temporally, nasally, superiorly and inferiorly from the corneal apex were obtained. The mean corneal thickness values along the 2, 4, 6, 8 and 10 mm diameter concentric circles, with the CTL as the centre, were also obtained. The above data at different points were statistically correlated. There was no significant difference between CCT readings measured by UP and Pentacam (P=0.721). There was high positive correlation between the CAT values and the thickness at 3 mm (R≥0.845, P<0.001) and at 7 mm points (R≥0.654, P<0.001). A gradual increase in thickness was noted from the centre to the periphery with a high positive correlation between the CTL values and the mean thickness at the circles of 2, 4, 6, 8 and 10 mm (R≥0.635, P<0.001). The results suggest that central corneal thickness can serve as a good guide for predicting peripheral thickness. For surgical procedures specifically undertaken at mid-peripheral and peripheral zones, the actual measurements at the site of surgery may confer some advantage. Copyright © 2011 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Corneal thickness and elevation measurements using swept-source optical coherence tomography and slit scanning topography in normal and keratoconic eyes.

PubMed

Jhanji, Vishal; Yang, Bingzhi; Yu, Marco; Ye, Cong; Leung, Christopher K S

2013-11-01

To compare corneal thickness and corneal elevation using swept source optical coherence tomography and slit scanning topography. Prospective study. 41 normal and 46 keratoconus subjects. All eyes were imaged using swept source optical coherence tomography and slit scanning tomography during the same visit. Mean corneal thickness and best-fit sphere measurements were compared between the instruments. Agreement of measurements between swept source optical coherence tomography and scanning slit topography was analyzed. Intra-rater reproducibility coefficient and intraclass correlation coefficient were evaluated. In normal eyes, central corneal thickness measured by swept source optical coherence tomography was thinner compared with slit scanning topography (p < 0.0001) and ultrasound pachymetry (p = < .0001). Ultrasound pachymetry readings had better 95% limits of agreement with swept source optical coherence tomography than slit scanning topography. In keratoconus eyes, central corneal thickness was thinner on swept source optical coherence tomography than slit scanning topography (p = 0.081) and ultrasound pachymetry (p = 0.001). There were significant differences between thinnest corneal thickness, and, anterior and posterior best-fit sphere measurements between both instruments (p < 0.05 for all). Overall, reproducibility coefficients and intraclass correlation coefficients were significantly better with swept source optical coherence tomography for measurement of central corneal thickness, anterior best-fit sphere and, posterior best-fit sphere (all p < 0.001). Corneal thickness and elevation measurements were significantly different between swept source optical coherence tomography and slit scanning topography. With better reproducibility coefficients and intraclass correlation coefficients, swept source optical coherence tomography may provide a reliable alternative for measurement of corneal parameters. © 2013 The Authors. Clinical and Experimental Ophthalmology © 2013 Royal Australian and New Zealand College of Ophthalmologists.

Standardised antibacterial Manuka honey in the management of persistent post-operative corneal oedema: a case series.

PubMed

Albietz, Julie M; Lenton, Lee M

2015-09-01

Corneal oedema is a common post-operative problem that delays or prevents visual recovery from ocular surgery. Honey is a supersaturated solution of sugars with an acidic pH, high osmolarity and low water content. These characteristics inhibit the growth of micro-organisms, reduce oedema and promote epithelialisation. This clinical case series describes the use of a regulatory approved Leptospermum species honey ophthalmic product, in the management of post-operative corneal oedema and bullous keratopathy. A retrospective review of 18 consecutive cases (30 eyes) with corneal oedema persisting beyond one month after single or multiple ocular surgical procedures (phacoemulsification cataract surgery and additional procedures) treated with Optimel Antibacterial Manuka Eye Drops twice to three times daily as an adjunctive therapy to conventional topical management with corticosteroid, aqueous suppressants, hypertonic sodium chloride five per cent, eyelid hygiene and artificial tears. Visual acuity and central corneal thickness were measured before and at the conclusion of Optimel treatment. A temporary reduction in corneal epithelial oedema lasting up to several hours was observed after the initial Optimel instillation and was associated with a reduction in central corneal thickness, resolution of epithelial microcysts, collapse of epithelial bullae, improved corneal clarity, improved visualisation of the intraocular structures and improved visual acuity. Additionally, with chronic use, reduction in punctate epitheliopathy, reduction in central corneal thickness and improvement in visual acuity were achieved. Temporary stinging after Optimel instillation was experienced. No adverse infectious or inflammatory events occurred during treatment with Optimel. Optimel was a safe and effective adjunctive therapeutic strategy in the management of persistent post-operative corneal oedema and warrants further investigation in clinical trials. © 2015 The Authors. Clinical and Experimental Optometry © 2015 Optometry Australia.

Limited Versus Total Epithelial Debridement Ocular Surface Injury: Live Fluorescence Imaging of Hemangiogenesis and Lymphangiogenesis in Prox1-GFP/Flk1::myr-mCherry Mice

PubMed Central

Chang, Jin-Hong; Putra, Ilham; Huang, Yu-hui; Chang, Michael; Han, Kyuyeon; Zhong, Wei; Gao, Xinbo; Wang, Shuangyong; Dugas-Ford, Jennifer; Nguyen, Tara; Hong, Young-Kwon; Azar, Dimitri T.

2016-01-01

Background Immunohistochemical staining experiments have shown that both hemangiogenesis and lymphangiogenesis occur following severe corneal and conjunctival injury and that the neovascularization of the cornea often has severe visual consequences. To better understand how hemangiogenesis and lymphangiogenesis are induced by different degrees of ocular injury, we investigated patterns of injury-induced corneal neovascularization in live Prox1-GFP/Flk1::myr-mCherry mice, in which blood and lymphatic vessels can be imaged simultaneously in vivo. Methods The eyes of Prox1-GFP/Flk1::myr-mCherry mice were injured according to four models based on epithelial debridement of the: A) central cornea (a 1.5-mm-diameter circle of tissue over the corneal apex), B) total cornea, C) bulbar conjunctiva, and D) cornea+bulbar conjunctiva. Corneal blood and lymphatic vessels were imaged on days 0, 3, 7, and 10 post-injury, and the percentages of the cornea containing blood and lymphatic vessels were calculated. Results Neither central corneal nor bulbar conjunctival debridement resulted in significant vessel growth in the mouse cornea, whereas total corneal and corneal+bulbar conjunctival debridement did. On day 10 in the central cornea, total cornea, bulbar conjunctiva, and corneal+bulbar conjunctival epithelial debridement models, the percentage of the corneal surface that was occupied by blood vessels (hemangiogenesis) was 1.9±0.8%, 7.14±2.4%, 2.29±1%, and 15.05±2.14%, respectively, and the percentage of the corneal surface that was occupied by lymphatic vessels (lymphangiogenesis) was 2.45±1.51%, 4.85±0.95%, 2.95±1.27%, and 4.15±3.85%, respectively. Conclusions Substantial corneal debridement was required to induce corneal neovascularization in the mouse cornea, and the corneal epithelium may therefore be partially responsible for maintaining corneal avascularity. General significance Our study demonstrates that GFP/Flk1::myr-mCherry mice are a useful model for studying coordinated hemangiogenic and lymphangiogenic responses. PMID:27233452

Corneal topography with an aberrometry-topography system.

PubMed

Mülhaupt, Michael; Dietzko, Sven; Wolffsohn, James; Bandlitz, Stefan

2018-05-07

To investigate the agreement between the central corneal radii and corneal eccentricity measurements generated by the new Wave Analyzer 700 Medica (WAV) compared to the Keratograph 4 (KER) and to test the repeatability of the instruments. 20 subjects (10 male, mean age 29.1 years, range 21-50 years) were recruited from the students and staff of the Cologne School of Optometry. Central corneal radii for the flat (r c/fl ) and steep (r c/st ) meridian as well as corneal eccentricity for the nasal (e nas ), temporal (e temp ), inferior (e inf ) and superior (e sup ) directions were measured using WAV and KER by one examiner in a randomized order. Central radii of the flat (r c/fl ) and steep (r c/st ) meridian measured with both instruments were statically significantly correlated (r = 0.945 and r = 0.951; p < 0.001). Comparison between the WAV and KER showed that r c/fl and r c/st measured with WAV were significantly steeper than those measured with KER (p < 0.001). Corneal eccentricities were statistically significantly correlated in all meridians (p < 0.05). Compared to KER, e temp and e sup measured with WAV were greater (p < 0.05), while there were no statistically significant differences for e nas and e inf (p = 0.350 and p = 0.083). For the central radii, repeated measurements were not significantly different for the KER or WAV (p > 0.05). Limits of agreement (LoA) indicate a better repeatability for the KER compared to WAV. Corneal topography measurements captured with the WAV were strongly correlated with the KER. However, due to the differences in measured corneal radii and eccentricities, the devices cannot be used interchangeably. For corneal topography the KER demonstrated better repeatability. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Overnight corneal swelling with high and low powered silicone hydrogel lenses.

PubMed

Moezzi, Amir M; Fonn, Desmond; Varikooty, Jalaiah; Simpson, Trefford L

2015-01-01

To compare central corneal swelling after eight hours of sleep in eyes wearing four different silicone hydrogel lenses with three different powers. Twenty-nine neophyte subjects wore lotrafilcon A (Dk, 140), balafilcon A (Dk, 91), galyfilcon A (Dk, 60) and senofilcon A (Dk, 103) lenses in powers -3.00, -10.00 and +6.00 D on separate nights, in random order, and on one eye only. The contra-lateral eye (no lens) served as the control. Central corneal thickness was measured using a digital optical pachometer before lens insertion and immediately after lens removal on waking. For the +6.00 D and -10.00 D, lotrafilcon A induced the least swelling and galyfilcon A the most. The +6.00 D power, averaged across lens materials, induced significantly greater central swelling than the -10.00 and -3.00 D (Re-ANOVA, p<0.001), (7.7±2.9% vs. 6.8±2.8% and 6.5±2.5% respectively) but there was no difference between -10.00 and -3.00 D. Averaged for power, lotrafilcon A induced the least (6.2±2.8%) and galyfilcon A the most (7.6±3.0%) swelling at the center (Re-ANOVA, p<0.001). Central corneal swelling with +6.00 D was significantly greater than -10.00 D lens power despite similar levels of average lens transmissibility of these two lens powers. The differences in corneal swelling of the lens wearing eyes are consistent with the differences in oxygen transmission of the silicone hydrogel lenses. In silicone hydrogel lenses central corneal swelling is mainly driven by central lens oxygen transmissibility. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Effect of Cycloplegia on Corneal Biometrics and Refractive State.

PubMed

Bagheri, Abbas; Feizi, Mohadeseh; Shafii, Aliakbar; Faramarzi, Amir; Tavakoli, Mehdi; Yazdani, Shahin

2018-01-01

To determine changes in refractive state and corneal parameters after cycloplegia with cyclopentolate hydrochloride 1% using a dual Scheimpflug imaging system. In this prospective cross-sectional study patients aged 10 to 40 years who were referred for optometric evaluation enrolled and underwent autorefraction and corneal imaging with the Galilei dual Scheimpflug system before and 30 minutes after twice instillation of medication. Changes in refraction and astigmatism were investigated. Corneal biometrics including anterior and posterior corneal curvatures, total corneal power and corneal pachymetry were compared before and after cycloplegia. Two hundred and twelve eyes of 106 subjects with mean age of 28 ± 5 years including 201 myopic and 11 hyperopic eyes were evaluated. Mean spherical equivalent refractive error before cycloplegia was -3.4 ± 2.6 D. A mean hyperopic shift of 0.4 ± 0.5 D occurred after cycloplegia ( P < 0.001). The astigmatism power did not significantly change ( P = 0.8), however, 26.8% of eyes with significant astigmatism experienced a change of more than 5 degrees in the axis of astigmatism. Changes in posterior corneal curvature were scant but statistically significant ( P = 0.001). Moreover, corneal thickness was slightly increased in the central and paracentral regions ( P < 0.001 and P < 0.001, respectively). Cycloplegia causes a hyperopic shift and astigmatism axis changes, along with an increase in central and paracentral corneal thickness and change in posterior corneal curvature. The effects of cycloplegia on refraction and corneal biometrics should be considered before cataract and refractive surgeries.

Evaluation of ABCG2 and p63 expression in canine cornea and cultivated corneal epithelial cells.

PubMed

Morita, Maresuke; Fujita, Naoki; Takahashi, Ayaka; Nam, Eun Ryel; Yui, Sho; Chung, Cheng Shu; Kawahara, Naoya; Lin, Hsing Yi; Tsuzuki, Keiko; Nakagawa, Takayuki; Nishimura, Ryohei

2015-01-01

To examine the expressions of ABCG2 and p63 in canine corneal epithelia and to evaluate their significance in corneal regeneration. Canine corneal and limbal epithelial cells were obtained from five healthy beagle dogs. We analyzed the morphological properties of cultivated limbal and corneal epithelial cells. We compared the expressions of ABCG2 and p63 in the limbus and central cornea by immunohistochemistry and real-time quantitative PCR. We analyzed the expression of these markers in cultivated cells by immunocytochemistry and real-time quantitative PCR. The limbal epithelial cells were smaller and proliferated more rapidly than the corneal epithelial cells in primary cultures. The corneal cells failed to be subcultured, whereas the limbal cells could be subcultured with increasing cell size. ABCG2 was localized in the basal layer of the limbal epithelium, and p63 was widely detected in the entire corneal epithelia. ABCG2 expression was significantly higher, and p63 was slightly higher in the limbus compared with the central cornea. ABCG2 was detected only in limbal cells in primary culture, not in corneal cells or passaged limbal cells. p63 was detected in both limbal and corneal cells and decreased gradually in the limbal cells with the cell passages. ABCG2 was localized in canine limbal epithelial cells, and p63 was widely expressed in canine corneal epithelia. ABCG2 and p63 could prove to be useful markers in dogs for putative corneal epithelial stem cells and for corneal epithelial cell proliferation, respectively. © 2014 American College of Veterinary Ophthalmologists.

Effect of central corneal thickness, corneal curvature, and axial length on applanation tonometry.

PubMed

Kohlhaas, Markus; Boehm, Andreas G; Spoerl, Eberhard; Pürsten, Antje; Grein, Hans J; Pillunat, Lutz E

2006-04-01

To evaluate the effect of central corneal thickness (CCT), corneal curvature, and axial length on applanation tonometry in an in vivo study. In a masked, prospective clinical trial, we examined 125 eyes of 125 patients scheduled for cataract surgery. Corneal curvature was measured by means of keratometry and axial length by A-scan ultrasonography. By cannulating the anterior chamber before surgery, intraocular pressure (IOP) was set to 20, 35, and 50 mm Hg in a closed system by means of a water column. After measuring thickness, the IOP was measured with an applanation tonometer. Pearson product moment correlations and multiple linear regression analyses were performed, and significance levels were evaluated by the paired, 2-tailed t test. The difference between measured and real IOP was significantly dependent (P < .001) on CCT. The associations between IOP and corneal curvature or IOP and axial length were not statistically significant (P = .31). The association between IOP reading and CCT is shown in the "Dresdner correction table," which illustrates an approximately 1-mm Hg correction for every 25-microm deviation from a CCT of 550 microm. The correction values were positive as thickness decreased and negative as thickness increased. Central corneal thickness significantly affects IOP readings obtained by applanation tonometry according to the Goldmann principle. A correction of IOP readings by considering CCT according to the Dresdner correction table might be helpful for determining an accurate IOP value.

Corneal Irregular Astigmatism and Curvature Changes After Small Incision Lenticule Extraction: Three-Year Follow-Up.

PubMed

Sideroudi, Haris; Lazaridis, Apostolos; Messerschmidt-Roth, Anke; Labiris, Georgios; Kozobolis, Vassilios; Sekundo, Walter

2018-04-27

To evaluate the long-term changes in anterior and posterior corneal irregular astigmatism and curvatures after small incision lenticule extraction (SMILE). Fifty eyes of 28 patients underwent SMILE for myopic astigmatism. All procedures were performed using the VisuMax® femtosecond laser. A Scheimpflug camera was used for preoperative and 3-year postoperative tomography. Anterior and posterior corneal Fourier parameters (spherical component, regular astigmatism, asymmetry, and irregularity) and curvature data were evaluated and compared within 2 subgroups according to the magnitude of the refractive correction (low myopia group: spherical equivalent (SEQ) ≥ -6 D; high myopia group: (SEQ) < -6 D). Associations between all studied parameters were examined. Three years postoperatively, an increase in anterior corneal curvatures and Fourier parameters was detected and the results were strongly correlated with the preoperative SEQ, lenticule thickness, and volume. At the posterior cornea, the flattest radius, corneal astigmatism, spherical component, regular astigmatism, and irregularity decreased only in the high myopia group. A correlation was found between changes in posterior astigmatism and changes in anterior radii (R = 0.349, P = 0.014), SEQ (R = 0.396, P = 0.0049), and lenticule thickness (R = -0.414, P = 0.0031). Moreover, changes in posterior corneal irregularity correlated with the changes in anterior and posterior radii (R = -0.3, P = 0.034, and R = 0.449, P = 0.0012, respectively), changes in preoperative SEQ (R = 0.284, P = 0.0477), and lenticule thickness (R = -0.311, P = 0.0298). Three years after SMILE, there was a reduction of posterior astigmatism in high refractive corrections. This could result in undercorrection in high refractive treatments. Total irregularities increased despite the compensatory effect of the posterior corneal surface.

Comparison of central corneal thickness measurement using ultrasonic pachymetry, rotating Scheimpflug camera, and scanning-slit topography.

PubMed

Sedaghat, Mohammad Reza; Daneshvar, Ramin; Kargozar, Abbas; Derakhshan, Akbar; Daraei, Mona

2010-12-01

To evaluate and compare central corneal thickness measurements using rotating Scheimpflug camera, scanning-slit topography, and ultrasound pachymetry in virgin, healthy corneas. Prospective, observational, cross-sectional study. Central corneal thickness in 157 healthy eyes of 157 patients without ocular abnormalities other than refractive errors was measured, in a sequential order, once with rotating Scheimpflug camera and scanning-slit topography and 3 times with ultrasound pachymetry as the last part of examination. All measurements were performed by a single experienced examiner. The results from scanning-slit topography are given with and without correction for "acoustic correction factor" of 0.92. The average measurements of central corneal thickness by rotating Scheimpflug imaging, scanning-slit pachymetry, and ultrasound were 537.15 ± 32.98 μm, 542.06 ± 39.04 μm, and 544.07 ± 34.75 μm, respectively. The mean differences between modalities were 6.92 μm between rotating Scheimpflug and ultrasound (P < .0001), 2.01 μm between corrected scanning-slit and ultrasound (P = .204), and 4.91 μm between corrected scanning-slit and rotating Scheimpflug imaging (P = .001). According to Bland-Altman analysis, highest agreement was between ultrasonic and rotating Scheimpflug pachymetry. In the assessment of normal corneas, rotating Scheimpflug topography measures central corneal thickness values with higher agreement to ultrasound pachymetry. Copyright © 2010 Elsevier Inc. All rights reserved.

Epidemiology and aetiological diagnosis of corneal ulceration in Madurai, south India

PubMed Central

Srinivasan, M; Gonzales, C.; George, C.; Cevallos, V.; Mascarenhas, J.; Asokan, B; Wilkins, J.; Smolin, G.; Whitcher, J.

1997-01-01

AIMS/BACKGROUND—To determine the epidemiological characteristics and risk factors predisposing to corneal ulceration in Madurai, south India, and to identify the specific pathogenic organisms responsible for infection.
METHODS—All patients with suspected infectious central corneal ulceration presenting to the ocular microbiology and cornea service at Aravind Eye Hospital, Madurai, from 1 January to 31 March 1994 were evaluated. Sociodemographic data and information pertaining to risk factors were recorded, all patients were examined, and corneal cultures and scrapings were performed.
RESULTS—In the 3 month period 434 patients with central corneal ulceration were evaluated. A history of previous corneal injury was present in 284 patients (65.4%). Cornea cultures were positive in 297 patients (68.4%). Of those individuals with positive cultures 140 (47.1%) had pure bacterial infections, 139 (46.8%) had pure fungal infections, 15 (5.1%) had mixed bacteria and fungi, and three (1.0%) grew pure cultures of Acanthamoeba. The most common bacterial pathogen isolated was Streptococcus pneumoniae, representing 44.3% of all positive bacterial cultures, followed by Pseudomonas spp (14.4%). The most common fungal pathogen isolated was Fusarium spp, representing 47.1% of all positive fungal cultures, followed by Aspergillus spp (16.1%).
CONCLUSIONS—Central corneal ulceration is a common problem in south India and most often occurs after a superficial corneal injury with organic material. Bacterial and fungal infections occur in equal numbers with Streptococcus pneumoniae accounting for the majority of bacterial ulcers and Fusarium spp responsible for most of the fungal infections. These findings have important public health implications for the treatment and prevention of corneal ulceration in the developing world.

 PMID:9505820

Central and peripheral corneal thinning in keratoconus.

PubMed

Brautaset, Rune L; Nilsson, Maria; Miller, William L; Leach, Norman E; Tukler, Johanna H; Bergmanson, Jan P G

2013-03-01

Recent data regarding the mid-peripheral portion of the removed corneal button in transplant surgery indicate histopathologically that keratoconus was present also in the peripheral portion of the button. The intent of this study was therefore to investigate if peripheral changes could also be detected clinically by measuring the central and peripheral corneal thickness of KC patients. Corneal pachymetry was measured with the Visante optical coherence tomography and Orbscan II. Of 52 subjects, 26 were KC subjects and 26 were age- and sex-matched control subjects. Corneal thickness, in KC patients, was significantly reduced in all areas compared with corneal thickness among controls with both the Visante optical coherence tomography and Orbscan II. The results of the present study have provided clinical evidence that KC is a disease affecting a wider area of the cornea. Although the KC cornea shows the greatest change in thickness in the ectatic region, this attenuation declines toward the periphery. The presence of peripheral thinning indicated that KC may be a "pancorneal" pathology and not limited to the ectatic portion.

Apparent Corneal Ectasia After Bilateral Intrastromal Femtosecond Laser Treatment for Presbyopia.

PubMed

Dukic, Adrijana; Bohac, Maja; Pasalic, Adi; Koncarevic, Mateja; Anticic, Marija; Patel, Sudi

2016-11-01

To report a case of apparent corneal ectasia after intrastromal femtosecond laser treatment for presbyopia (INTRACOR). A healthy 56-year-old male with low hyperopia underwent an unremarkable bilateral INTRACOR procedure in March/April 2011. The patient was discharged after follow-up and returned 5 years later. Before discharge, the monocular logarithm of the minimal angle of resolution uncorrected distance visual acuity (UDVA) values were R, 0.0 and L, 0.10. In both eyes near (UNVA) visual acuities were 0.0. There were signs of slight posterior central corneal steepening without loss of corneal stability. Five years postop, monocular UDVA and UNVA values were 0.4 and 0.0, respectively. Ectasia was observed in both eyes, and the centrally placed 5 concentric rings after the INTRACOR procedure were visible under slit-lamp biomicroscopy. There is no clear reason to explain why the patient developed bilateral corneal steepening. It could be that the patient's corneal stromal fibers gradually weakened over this 5-year period.

Effect of Cycloplegia on Corneal Biometrics and Refractive State

PubMed Central

Bagheri, Abbas; Feizi, Mohadeseh; Shafii, Aliakbar; Faramarzi, Amir; Tavakoli, Mehdi; Yazdani, Shahin

2018-01-01

Purpose: To determine changes in refractive state and corneal parameters after cycloplegia with cyclopentolate hydrochloride 1% using a dual Scheimpflug imaging system. Methods: In this prospective cross-sectional study patients aged 10 to 40 years who were referred for optometric evaluation enrolled and underwent autorefraction and corneal imaging with the Galilei dual Scheimpflug system before and 30 minutes after twice instillation of medication. Changes in refraction and astigmatism were investigated. Corneal biometrics including anterior and posterior corneal curvatures, total corneal power and corneal pachymetry were compared before and after cycloplegia. Results: Two hundred and twelve eyes of 106 subjects with mean age of 28 ± 5 years including 201 myopic and 11 hyperopic eyes were evaluated. Mean spherical equivalent refractive error before cycloplegia was -3.4 ± 2.6 D. A mean hyperopic shift of 0.4 ± 0.5 D occurred after cycloplegia (P < 0.001). The astigmatism power did not significantly change (P = 0.8), however, 26.8% of eyes with significant astigmatism experienced a change of more than 5 degrees in the axis of astigmatism. Changes in posterior corneal curvature were scant but statistically significant (P = 0.001). Moreover, corneal thickness was slightly increased in the central and paracentral regions (P < 0.001 and P < 0.001, respectively). Conclusion: Cycloplegia causes a hyperopic shift and astigmatism axis changes, along with an increase in central and paracentral corneal thickness and change in posterior corneal curvature. The effects of cycloplegia on refraction and corneal biometrics should be considered before cataract and refractive surgeries. PMID:29719636

Morphological Changes of Human Corneal Endothelial Cells after Rho-Associated Kinase Inhibitor Eye Drop (Ripasudil) Administration: A Prospective Open-Label Clinical Study

PubMed Central

Okumura, Naoki; Suganami, Hideki; Kinoshita, Shigeru

2015-01-01

Purpose To investigate the effect and safety of a selective Rho kinase inhibitor, ripasudil 0.4% eye drops, on corneal endothelial cells of healthy subjects. Design Prospective, interventional case series. Methods In this study, 6 healthy subjects were administered ripasudil 0.4% in the right eye twice daily for 1 week. Morphological changes and corneal endothelial cell density were examined by noncontact and contact specular microscopy. Central corneal thickness and corneal volume of 5 mm-diameter area of center cornea were analyzed by Pentacam Scheimpflug topography. All the above measurements were conducted in both eyes before administration, 1.5 and 6 hours after the initial administration on day 0; and in the same manner after the final administration on day 7. Results By noncontact specular microscopy, indistinct cell borders with pseudo guttae were observed, but by contact specular microscopy, morphological changes of corneal endothelial cells were mild and pseudo guttae was not observed after single and repeated administration of ripasudil in all subjects. These changes resolved prior to the next administration, and corneal endothelial cell density, central corneal thickness and corneal volume were not changed throughout the study period. Conclusion Transient morphological changes of corneal endothelial cells such as indistinct cell borders with pseudo guttae were observed by noncontact specular microscopy in healthy subjects after ripasudil administration. Corneal edema was not observed and corneal endothelial cell density did not decrease after 1 week repetitive administration. These morphological changes were reversible and corneal endothelial cell morphology returned to normal prior to the next administration. Trial Registration JAPIC Clinical Trials Information 142705 PMID:26367375

The brilliant beauty of the eye: light reflex from the cornea and tear film.

PubMed

Goto, Eiki

2006-12-01

Light reflex from the cornea and tear film as contributors to beautiful eyes ("eye sparkling") are reviewed. A systematic literature review was conducted using "Purkinje-Sanson image," "corneal light reflex," "corneal topography," "corneal wavefront aberration," and "tear interference image" as search terms. Articles on corneal surface regularity and stability and tear interferometry of the precorneal tear lipid layer were reviewed. PS-1 image, that is light reflex from the cornea and tear film, is widely used in practical ophthalmic examination. To achieve a brilliant beauty of the eye ("eye sparkling"), it is important that the tear film (aqueous layer) surface is smooth and stable with adequate tear volume and that the tear lipid layer is present in adequate thickness.

A noncontact pneumatic esthesiometer for measurement of ocular sensitivity: a preliminary report.

PubMed

Vega, J A; Simpson, T L; Fonn, D

1999-11-01

The aim of this investigation was to evaluate a prototype noncontact pneumatic esthesiometer for measuring sensitivity of the eye. To evaluate the instrument's repeatability, central corneal sensitivity was recorded on two separate occasions with a 24-h interval between the two measures. In a separate experiment, corneal edema was induced with a thick hydrogel lens, and the eye was closed and patched. Corneal sensitivity was measured before wearing the lenses for 3 h, immediately after lens removal, and 15 min later. Corneal sensitivity also was measured before the instillation of a single drop of proparacaine (Alcaine, 0.5%) and at 2 and 18 min later. Sensitivity was measured at the corneal apex and at a temporal conjunctival location 3 mm from the limbus. A high correlation was found between days 1 and 2 (r = 0.90; p = 0.0001). The coefficient of repeatability (COR = 0.87 mm Hg) showed that 95% of the difference between test and retest measures were between +/-0.87 mm Hg. Corneal sensitivity decreased by 55% after lens-induced corneal swelling and by 159% after instillation of the topical anesthetic. Central corneal sensitivity was found to be significantly higher than that of the temporal conjunctiva (p = 0.0001). We conclude that this pneumatic esthesiometer provides repeatable and reliable measures of ocular-surface sensitivity.

A novel gelatin hydrogel carrier sheet for corneal endothelial transplantation.

PubMed

Watanabe, Ryou; Hayashi, Ryuhei; Kimura, Yu; Tanaka, Yuji; Kageyama, Tomofumi; Hara, Susumu; Tabata, Yasuhiko; Nishida, Kohji

2011-09-01

We examined the feasibility of using gelatin hydrogels as carrier sheets for the transplantation of cultivated corneal endothelial cells. The mechanical properties, transparency, and permeability of gelatin hydrogel sheets were compared with those of atelocollagen sheets. Immunohistochemistry (ZO-1, Na(+)/K(+)-ATPase, and N-cadherin), hematoxylin and eosin staining, and scanning electron microscopy were performed to assess the integrity of corneal endothelial cells that were cultured on gelatin hydrogel sheets. The gelatin hydrogel sheets displayed greater transparency, elastic modulus, and albumin permeability compared to those of atelocollagen sheets. The corneal endothelial cells on gelatin hydrogel sheets showed normal expression levels of ZO-1, Na(+)/K(+)-ATPase, and N-cadherin. Hematoxylin and eosin staining revealed the formation of a continuous monolayer of cells attached to the gelatin hydrogel sheet. Scanning electron microscopy observations showed that the corneal endothelial cells were arranged in a regular, mosaic, and polygonal pattern with normal cilia. These results indicate that the gelatin hydrogel sheet is a promising material to transport corneal endothelial cells during transplantation.

Corneal biomechanical properties in thyroid eye disease.

PubMed

Karabulut, Gamze Ozturk; Kaynak, Pelin; Altan, Cıgdem; Ozturker, Can; Aksoy, Ebru Funda; Demirok, Ahmet; Yılmaz, Omer Faruk

2014-06-01

The purpose of this study is to investigate the effect of thyroid eye disease (TED) on the measurement of corneal biomechanical properties and the relationship between these parameters and disease manifestations. A total of 54 eyes of 27 individuals with TED and 52 eyes of 30 healthy control participants were enrolled. Thyroid ophthalmopathy activity was defined using the VISA (vision, inflammation, strabismus, and appearance/exposure) classification for TED. The intraocular pressure (IOP) measurement with Goldmann applanation tonometer (GAT), axial length (AL), keratometry, and central corneal thickness (CCT) measurements were taken from each patient. Corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF) and noncontact IOP measurements, Goldmann-correlated IOP (IOPg) and corneal-compensated IOP (IOPcc) were measured with the Ocular Response Analyzer (ORA) using the standard technique. Parameters such as best corrected visual acuity, axial length, central corneal thickness, and corneal curvature were not statistically significant between the two groups (p > 0.05). IOP measured with GAT was higher in participants with TED (p < 0.001). The CH of TED patients was significantly lower than that of the control group. There was no significant difference in the corneal resistance factor between groups. However, IOPg and IOPcc were significantly higher in TED patients. CH and VISA grading of TED patients showed a negative correlation (p = 0.007). In conclusion, TED affects the corneal biomechanical properties by decreasing CH. IOP with GAT and IOPg is found to be increased in these patients. As the severity of TED increases, CH decreases in these patients. Copyright © 2014. Published by Elsevier B.V.

Myopic keratomileusis by excimer laser on a lathe.

PubMed

Ganem, S; Aron-Rosa, D; Gross, M; Rosolen, S

1994-01-01

We designed an excimer laser keratomileusis delivery system to increase the regularity of the refractive cut surface and allow greater precision in the level and shape of the ablated zone. A parallel faced corneal disc was produced by microkeratectomy from six human eyes and surgical keratectomy in 12 beagle corneas. A 193-nanometer excimer laser that was used to project an oval beam onto the corneal disc was rotated on a flat surface to ensure overlapping of the ovally ablated areas between pulses. Electron microscopy of eye bank lenticules demonstrated a circular smooth regularly concave ablation zone. Histological examination of nine clear corneas confirmed thinning of the stroma without fibroblastic reaction and no epithelial hypertrophy. Mean preoperative corneal power of 43.15 +/- 2.18 decreased postoperatively to 33.61 +/- 2.34. The new technique of excimer laser keratomileusis has the advantage of a cut surface smoother and the clear zone is devoid of the stepwise concavity and irregularity seen in diaphragm based photoablation delivery systems.

Effects of immersion solution on corneal tissue strip hydration and thickness during thermal shrinkage

NASA Astrophysics Data System (ADS)

Borja, David; Manns, Fabrice; Lamar, Peggy D.; Rosen, Alexander; Parel, Jean-Marie A.

2003-07-01

Purpose: To assess the effects of immersion solutions with different Dextran concentrations on the hydration of cornea tissue strips at normal body temperature. Methods: A 20% Dextran-BSS solution was injected via a self sealing limbal-transcorneal tunnel incision using a 30ga needle into the anterior chamber of human donor eyes until the globe was hard. The eyes were then immersed cornea down overnight in the same solution. Corneal thickness was measured by ultrasound pachymetry after the eyes were re-inflated and at regular intervals to assess dehydration. When the central cornea thickness reached 400-500μm corneal buttons were removed using a 10mm trephine. The buttons were then cut into 6x6mm strips using a custom-made jig and immediately immersed in solutions of Dextran (15 to 20% in increments of 2.5%) at 35degC. The edge thickness of the immersed strip was measured every 5 min for one hour using an optical comparator (Topcon, Japan) modified for tissue shadowphotogrammetry. Results: For five Florida Lions Eye Bank donated eyes after one hour in the Dextran solution the mean final measured thickness of corneas in 20%, 17.5% and 15% Dextran-BSS solutions were 570 (+/-75) μm, 680 (+/-70) μm, and 1080 (+/-95) μm respectively. These measured thicknesses changes correspond to an average swelling of 1.2, 1.4 and 2.2 times the initial thickness of each cornea strip in the 20%, 17.5% and 15% Dextran-BSS solutions respectively. Conclusion: We will conduct experiments at higher Dextran concentrations but our current results indicate that 20% Dextran-BSS solution was the best solution tested at keeping corneal tissue strips at or close to physiological thickness.

Primary central corneal hemangiosarcoma in a dog.

PubMed

Haeussler, David J; Rodríguez, Laura Muñoz; Wilkie, David A; Premanandan, Chris

2011-03-01

To report a case of primary central corneal hemangiosarcoma in the dog. An 11-year-old, neutered, female, German shepherd mixed breed dog was referred to the Hospital Veterinario Sierra de Madrid (Spain) for evaluation of an enlarging corneal mass of the left eye (OS). The dog was predominantly housed outdoors and was diagnosed with a history of chronic superficial keratitis of both eyes (OU) by the referring veterinarian. The corneal mass was resected by routine superficial keratectomy and submitted for histopathology and Factor VIII immunohistochemical staining. The mass was diagnosed as a corneal hemangiosarcoma with complete excision. Postoperatively, the keratectomy site healed without complication and there was no evidence of recurrence three and a half months postoperatively. Complete systemic evaluation, including abdominal ultrasound and CT scan of the head and thorax, indicated no other detectable neoplasia in the dog. Outdoor housing and ultraviolet exposure, breed, and chronic superficial keratitis were all suspected as contributing factors to the development of a primary corneal hemangiosarcoma. Surgical removal and postoperative treatment for chronic superficial keratitis provided effective therapy. © 2011 American College of Veterinary Ophthalmologists.

Importance of accurately assessing biomechanics of the cornea.

PubMed

Roberts, Cynthia J

2016-07-01

This article summarizes the state-of-the-art in clinical corneal biomechanics, including procedures in which biomechanics play a role, and the clinical consequences in terms of error in estimating intraocular pressure (IOP). Corneal biomechanical response to refractive surgery can be categorized into either stable alteration of surface shape and thus visual outcome, or unstable biomechanical decompensation. The stable response is characterized by central flattening and peripheral steepening that is potentiated in a stiffer cornea. Two clinical devices for assessing corneal biomechanics do not yet measure classic biomechanical properties, but rather provide assessment of corneal deformation response. Biomechanical parameters are a function of IOP, and both the cornea and sclera become stiffer as IOP increases. Any assessment of biomechanical parameters must include IOP, and one value of stiffness does not adequately characterize a cornea. Corneal biomechanics plays a role in the outcomes of any procedure in which lamellae are transected. Once the corneal structure has been altered in a manner that includes central thinning, IOP measurements with applanation tonometry are likely not valid, and other technologies should be used.

Assessment of refractive astigmatism and simulated therapeutic refractive surgery strategies in coma-like-aberrations-dominant corneal optics.

PubMed

Zhou, Wen; Stojanovic, Aleksandar; Utheim, Tor Paaske

2016-01-01

The aim of the study is to raise the awareness of the influence of coma-like higher-order aberrations (HOAs) on power and orientation of refractive astigmatism (RA) and to explore how to account for that influence in the planning of topography-guided refractive surgery in eyes with coma-like-aberrations-dominant corneal optics. Eleven eyes with coma-like-aberrations-dominant corneal optics and with low lenticular astigmatism (LA) were selected for astigmatism analysis and for treatment simulations with topography-guided custom ablation. Vector analysis was used to evaluate the contribution of coma-like corneal HOAs to RA. Two different strategies were used for simulated treatments aiming to regularize irregular corneal optics: With both strategies correction of anterior corneal surface irregularities (corneal HOAs) were intended. Correction of total corneal astigmatism (TCA) and RA was intended as well with strategies 1 and 2, respectively. Axis of discrepant astigmatism (RA minus TCA minus LA) correlated strongly with axis of coma. Vertical coma influenced RA by canceling the effect of the with-the-rule astigmatism and increasing the effect of the against-the-rule astigmatism. After simulated correction of anterior corneal HOAs along with TCA and RA (strategies 1 and 2), only a small amount of anterior corneal astigmatism (ACA) and no TCA remained after strategy 1, while considerable amount of ACA and TCA remained after strategy 2. Coma-like corneal aberrations seem to contribute a considerable astigmatic component to RA in eyes with coma-like-aberrations dominant corneal optics. If topography-guided ablation is programmed to correct the corneal HOAs and RA, the astigmatic component caused by the coma-like corneal HOAs will be treated twice and will result in induced astigmatism. Disregarding RA and treating TCA along with the corneal HOAs is recommended instead.

Construction of a human corneal stromal equivalent with non-transfected human corneal stromal cells and acellular porcine corneal stromata.

PubMed

Diao, Jin-Mei; Pang, Xin; Qiu, Yue; Miao, Ying; Yu, Miao-Miao; Fan, Ting-Jun

2015-03-01

A tissue-engineered human corneal stroma (TE-HCS) has been developed as a promising equivalent to the native corneal stroma for replacement therapy. However, there is still a crucial need to improve the current approaches to render the TE-HCS equivalent more favorable for clinical applications. At the present study, we constructed a TE-HCS by incubating non-transfected human corneal stromal (HCS) cells in an acellular porcine corneal stromata (aPCS) scaffold in 20% fetal bovine serum supplemented DMEM/F12 (1:1) medium at 37 °C with 5% CO2in vitro. After 3 days of incubation, the constructed TE-HCS had a suitable tensile strength for transplantation, and a transparency that is comparable to native cornea. The TE-HCS had a normal histological structure which contained regularly aligned collagen fibers and differentiated HCS cells with positive expression of marker and functional proteins, mimicking a native HCS. After transplantation into rabbit models, the TE-HCS reconstructed normal corneal stroma in vivo and function well in maintaining corneal clarity and thickness, indicating that the completely biological TE-HCS could be used as a HCS equivalent. The constructed TE-HCS has promising potentials in regenerative medicine and treatment of diseases caused by corneal stromal disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

A case of unilateral circumscribed posterior keratoconus evaluated by three different imaging tools: optical coherence tomography, videokeratography, and Scheimpflug corneal tomography.

PubMed

Spadea, Leopoldo; Maraone, Giorgia; Cagini, Carlo

2017-02-01

Posterior keratoconus is a rare corneal anomaly which is part of the ectatic corneal disorders. We report a clinical presentation of a unilateral posterior keratoconus in a 42-year-old man. At the time of presentation, corrected distance visual acuity (CDVA) was 20/20 with a correction of +2.50 +2.50 × 90° in the right eye and 20/40 with +1 +3.00 × 105° in the left eye. Slit lamp microscopy showed in the left eye an evidence of corneal thinning with a mild anterior protrusion and a remarkable posterior excavation. The intraocular pressure was 19 mmHg in right eye and 16 mmHg in left eye. Ultrasound pachymetry showed a minimum corneal thickness of 556 μ in right eye and 289 μ in left eye. The anterior segment optical coherence tomography (AS-OCT) revealed central corneal thinning and showed a reduced epithelial thickness. Videokeratography showed an increase of the corneal curvature in a defined area with central steepening in the area of the posterior corneal depression with gradual paracentral flattening. The description of this case underlines the importance of this instruments such us AS-OCT and corneal topography in diagnosis of posterior keratoconus. It can also be observed that in the contralateral eye there are no signs of ectasia as in the rare condition of unilateral keratoconus.

[Clinical observation on corneal transparency after small incision lenticule extraction surgery].

PubMed

Zhang, L; Wang, Y; Cui, T; Zhao, W; Cheng, W B

2018-01-11

Objective: To evaluate the changes of corneal transparency over the 1-year period after small incision lenticule extraction (SMILE) according to corneal Scheimpflug densitometry. Methods: Prospective cohort study. Fifty-five patients (100 eyes) with myopia (19 male and 36 female, aged 18 to 39 years with average of 24) who underwent SMILE and regular follow-up for at least 1 year at Tianjin Eye Hospital were enrolled. Examinations took place before SMILE and postoperatively at 1 day, 1 week, and 1, 3, 6, and 12 months. The preoperative spherical equivalent of surgical refractive correction was (-5.75±1.64) D. Corneal densitometry (CD) data were calculated automatically by the Pentacam Scheimpflug system and expressed in gray scale units (GSU), from 0 (completely transparent) to 100 (completely opaque). During the analysis of corneal densitometry, the average corneal optical density of three concentric radial zones centered on the apex of the cornea ≤2 mm, >2 mm and ≤6 mm, >6 mm and ≤10 mm diameter) were applied, and three layers were defined according to different corneal depths (the anterior 120 μm as 1st layer, and the posterior 60 μm as 3rd layer, and the center part between them of the cornea as 2nd layer). The automatic release mode was applied in order to avoid operator-induced errors. The preoperative and postoperative values in different corneal layers and different concentric radial zones were compared using Kruskal-Wallis. Results: Ninty-three eyes(93%) of all eyes achieved uncorrected distance visual acuity (UCVA) of 0.8 or better on the first day postoperatively, and 96% (96 of 100 eyes) achieved UCVA of 0.8 or better in the first week postoperatevely, and all eyes 100% (100 of 100 eyes) achieved UCVA 0.8 or better until the end of our follow-up (in 1 year postoperatively). In general, the difference preoperative and postoperative corneal average optical density is of no statistical significance (χ(2)=8.446, P =0.207), specifically, the overall postoperative CD increased in the first week after surgery (1 day to 15.90, 1 week to 15.65), and then decreased to the equivalent of baseline levels and maintained such level until 6 months after surgery (1 month to 15.60; 3 month to 15.50, 6 month to 15.55), though at the 12-month follow-up, densitometry values had spiked significantly again (12 month, 15.90). The difference between the preoperative and postoperative CD values in the central two zones (≤2 mm, >2 mm and ≤6 mm), but not the outer (>6 mm and ≤10 mm), were of statistical significance (χ(2)=61.961, 52.397, P< 0.000). When subdivided by corneal layer, significant changes in CD were detected in the anterior 120 μm layer (χ(2)=27.774, P< 0.000). The CD increased significantly (i.e., corneal transparency decreased) as compared to the preoperative baseline on the first postoperative day, and lasted through the first week. There were no significant changes in the CD of the central layer (χ(2)=0.918, P =0.986). Significant increases in the posterior 60 μm of the cornea after surgery were found only at the 6-month and 1-year follow-up examinations (χ(2)=17.469, P= 0.008). No correlation was found in the preoperative refractive error, ablation depth, postoperative UCVA and the CD. The CD at 6 months was found negatively correlated with SE at 6 months ( r= -0.219, P =0.028). Conclusions: SMILE reduced corneal transparency temporarily and primarily within the surgically altered area, however such change has no significant correlation with the ablation depth, SE, and the postoperative UCVA. Transparency recovered within a month, but patients should be monitored for at least 1 year. (Chin J Ophthalmol, 2018, 54: 27-32) .

Effects of silicone hydrogel contact lenses on ocular surface after Sub-Bowman's Keratomileusis.

PubMed

Gao, Shaohui; Wu, Junshu; Li, Lili; Wang, Yong; Zhong, Xingwu

2013-11-01

To evaluate the efficacy of silicone hydrogel contact lenses on ocular surface after Sub-Bowman Keratomileusis (SBK). Forty-six patients suffered from myopia underwent a bilateral SBK. Post-operatively, one eye of each patient wore a PureVision contact lens for 24 h as a treated eye and the contralateral eye was as a blank control. Afterwards, corneal fluorescein (FL) staining, tear break-up time (TBUT), schirmer I test (SIT), central corneal thickness (CCT), ocular surface disease index (OSDI), corneal hysteresis (CH), corneal resistance factor (CRF) and corneal flap complications were assessed 1 d (except for CH and CRF), 1 week, 1 month and 3 months postoperatively. Following SBK, in contrast to the control, corneal fluorescein staining of treated eyes were significantly reduced and tear break-up time of treated eyes were significantly improved at 1 d and 1 week after SBK. However, Schirmer I test of treated and control eyes were not different after SBK. Central corneal thickness of treated eyes were significantly thinner than that of control at 1 d after SBK, however, there were no differences at other time points. Ocular surface disease index of treated eyes were obviously alleviated more than that of control at 1 d after SBK, but no differences were found at other visits. Moreover, Corneal hysteresis and corneal resistance factor of treated and un-treated eyes were not different after surgery. And also the rate of corneal flap complications were not different between treated and control eyes after SBK. Silicone hydrogel contact lenses played a positive role in accelerating corneal epithelial healing, enhancing tear film stability and reducing discomfort of patients in the early stage after SBK.

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

Cenedella, R.J.; Fleschner, C.R.

The authors developed a direct chemical approach for estimating the rate of turnover of the corneal epithelium in vivo. The method was used to examine the effects of lovastatin, a potent inhibitor of cholesterol biosynthesis, on proliferation and turnover of the epithelium. Corneal DNA was labeled by pulse injection (IP) of the rat with 3H-thymidine, and 3H-labeled DNA was recovered from peripheral and central corneas over the next 15 days. Only the epithelium became labeled, and the loss of label by cell desquamation began 3 days after injection. The loss of 3H-DNA from the cornea (peripheral plus central region) followedmore » first-order kinetics. The half-life of the disappearance was about 3 days. The peripheral cornea became more highly labeled than the central cornea and began to lose 3H-DNA before the central cornea. These observations support the possibility of a higher mitotic rate in the peripheral region and the centripetal movement of a population of peripheral epithelial cells in the normal cornea. The half-lives of the disappearance of 3H-DNA from peripheral and central corneas measured between days 5 and 15 postinjection were identical, both at 3 days. Complete turnover of the corneal epithelium would, therefore, require about 2 weeks (4-5 half-lives). Treatment of the rat with lovastatin had no obvious effects upon the proliferation or turnover of the corneal epithelium. Although lovastatin inhibited corneal 3-hydroxy-3-methylglutaryl coenzyme A reductase, the key regulatory enzyme of cholesterol synthesis, the cornea compensated by induction of this enzyme so that there was no net inhibition of cholesterol synthesis in the cornea.« less

Severe acute corneal hydrops in a patient with Down syndrome and persistent eye rubbing.

PubMed

Ozcan, Altan A; Ersoz, T Reha

2007-01-01

We report a case of severe acute corneal hydrops in an 11-year-old boy with keratoconus associated with Down syndrome and vigorous eye rubbing. Complete resolution of the corneal edema and a central corneal scar was seen in the 8th week of final follow-up. Eye-rubbing may play a role in the pathogenesis of acute hydrops, and conventional therapy can be successful in its management, even in severe cases.

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.

Comparison of central corneal thickness measurements by rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit corneal topography.

PubMed

Amano, Shiro; Honda, Norihiko; Amano, Yuki; Yamagami, Satoru; Miyai, Takashi; Samejima, Tomokazu; Ogata, Miyuki; Miyata, Kazunori

2006-06-01

To compare central corneal thickness measurements and their reproducibility when taken by a rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit corneal topography/pachymetry. Experimental study. Seventy-four eyes of 64 subjects without ocular abnormalities other than cataract. Corneal thickness measurements were compared among the 3 methods in 54 eyes of 54 subjects. Two sets of measurements were repeated by a single examiner for each pachymetry in another 10 eyes of 5 subjects, and the intraexaminer repeatability was assessed as the absolute difference of the first and second measurements. Two experienced examiners took one measurement for each pachymetry in another 10 eyes of 5 subjects, and the interexaminer reproducibility was assessed as the absolute difference of the 2 measurements of the first and second examiners. Central corneal thickness measurements by the 3 methods, absolute difference of the first and second measurements by a single examiner, absolute difference of the 2 measurements by 2 examiners, and relative amount of variation. The average measurements of central corneal thickness by a rotating Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry were 538+/-31.3 microm, 541+/-40.7 microm, and 545+/-31.3 microm, respectively. There were no statistically significant differences in the measurement results among the 3 methods (P = 0.569, repeated-measures analysis of variance). There was a significant linear correlation between the rotating Scheimpflug camera and ultrasonic pachymetry (r = 0.908, P<0.0001), rotating Scheimpflug camera and scanning-slit topography (r = 0.930, P<0.0001), and ultrasonic pachymetry and scanning-slit topography (r = 0.887, P<0.0001). Ultrasonic pachymetry had the smallest intraexaminer variability, and scanning-slit topography had the largest intraexaminer variability among the 3 methods. There were similar variations in interexaminer reproducibility among the 3 methods. Mean corneal thicknesses were comparable among rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit topography with the acoustic equivalent correction factor. The measurements of the 3 instruments had significant linear correlations with one another, and all methods had highly satisfactory measurement repeatability.

[What should we think? Is pneumotonometry still reliable?].

PubMed

Bresson-Dumont, H; Lehoux, A; Kponoume, C; Santiago, P-Y

2007-05-01

Noncontact tonometer (NCT) is an applanation tonometry, as is Goldmann tonometry. Numerous studies have shown the reliability of this technique but problems still exist. We measured intraocular pressure (IOP) in 340 patients (668 eyes) with NCT and Goldmann tonometer (GAT). To evaluate the influence of central corneal thickness (CCT), we classified the patients according to their CCT (<500 microm; between 520 and 580 microm, and>600 microm). The mean difference between the two IOP measurements was -1.4 mmHg +/- 2.67 (-12 to +7), p<0,0001 for the thinner corneas, +0.13 mmHg +/- 2.67 (-8 to +8), p=0.445 for the regular corneas, and + 3.04 mmHg +/- 3.2 (-7 to +13) p<0.0001 for the thicker corneas. CCT influences NCT and GAT, but the difference between the two techniques is higher for thicker CCTs, higher IOPs, and in younger patients. NCT is good for glaucoma screening but is less reliable than GAT for glaucoma follow-up if CCT and IOP are far from regular values.

Analysis of corneal topography in patients with pure microphthalmia in Eastern China.

PubMed

Hu, Pei-Hong; Gao, Gui-Ping; Yu, Yao; Pei, Chong-Gang; Zhou, Qiong; Huang, Xin; Zhang, Ying; Shao, Yi

2015-12-01

To determine the typical corneal changes in pure microphthalmia using a corneal topography system and identify characteristics that may assist in early diagnosis. Patients with pure microphthalmia and healthy control subjects underwent corneal topography analysis (Orbscan IIZ® Corneal Topography System; Bausch and Lomb, Bridgewater, NJ, USA) to determine degree of corneal astigmatism (mean A), simulation of corneal astigmatism (sim A), mean keratometry (mean K), simulated keratometry (sim K), irregularities in the 3 - and 5-mm zone, and mean thickness of nine distinct corneal regions. Patients with pure microphthalmia (n = 12) had significantly higher mean K, sim K, mean A, sim A, 3.0 mm irregularity and 5.0 mm irregularity, and exhibited significantly more false keratoconus than controls (n = 12). There was a significant between-group difference in the morphology of the anterior corneal surface and the central curvature of the cornea. Changes in corneal morphology observed in this study could be useful in borderline situations to confirm the diagnosis of pure microphthalmia. © The Author(s) 2015.

Evaluation of biometry and corneal astigmatism in cataract surgery patients from Central China.

PubMed

Yu, Ji-Guo; Zhong, Jie; Mei, Zhong-Ming; Zhao, Fang; Tao, Na; Xiang, Yi

2017-04-26

To evaluate the distribution of biometric parameters and corneal astigmatism using the IOLMaster device before phacoemulsification in cataract patients in Central China. Consecutive cataract patients were recruited at the Central Hospital of Wuhan between January 2015 and June 2016. Ocular axial length (AL), keratometry values, anterior chamber depth (ACD) and horizontal corneal diameter (white to white [WTW]) of each cataract-affected eye were measured with the IOLMaster device. The study evaluated 3209 eyes of 2821 cataract patients. The mean AL, ACD, and WTW were 24.38 ± 2.47 mm, 3.15 ± 0.48 mm, and 11.63 ± 0.43 mm, respectively. Corneal astigmatism of 0.51-1.00 diopters (D) was the most common range of values (34.96%). A total of 10.56% patients exhibited a corneal astigmatism greater than 2.0 D. The flat and steep keratometry values gradually increased with age. The mean ACD and WTW showed increasing trends as the AL increased (P < 0.001). When the AL was shorter than 26.0 mm, the keratometry decreased as AL increased. The against-the-rule (ATR) astigmatism proportion increased with age and the with-the-rule (WTR) astigmatism proportion decreased with age. The profile of ocular biometric data and corneal astigmatism may help ophthalmologists improve their surgical procedures and make an appropriate IOL choice to gain a high quality of postoperative vision.

Regional variation in the refractive-index of the bovine and human cornea.

PubMed

Vasudevan, Balamurali; Simpson, Trefford L; Sivak, Jacob G

2008-10-01

Given the refractive importance of the human cornea, surprisingly little attention has been directed to the study of local variation in corneal refractive-index. This in vitro and in vivo study measures the refractive-index of different portions of the bovine and human cornea. Fifty fresh bovine corneas (obtained from an abattoir) and 10 human subjects were used for the study. The refractive-index of the central, nasal, and temporal corneal epithelium was measured with a bench-top Abbe refractometer in the case of bovine corneas and with a hand-held refractometer with humans. The mean (+/-standard deviation) refractive-indices of the central, nasal, and temporal bovine corneal epithelium were 1.3760 (+/-0.003), 1.3757 (+/-0.002), and 1.3746 (+/-0.002), respectively. Refractive-indices of the anterior and posterior bovine corneal stroma were 1.3731 (+/-0.002) and 1.3708 (+/-0.004), respectively. The mean (+/-standard deviation) refractive-index in the central, nasal, and temporal periphery of the human cornea epithelium were 1.3970 (+/-0.001), 1.3946 (+/-0.001), and 1.3940 (+/-0.001), respectively. There are small local differences in the refractive-index of the bovine and human corneal epithelium and the refractive-index of the epithelium is higher than that of the anterior and posterior stroma of the bovine cornea.

[Possible complications of orthokeratology in myopia correction].

PubMed

Borodina, N V; Musaeva, G M; Kobzova, M V

2011-01-01

Clinical cases representing complications (refractive, infectious and trophic) of orthokeratologic lenses (OKL) use are described. These clinical cases show that complications of OKL use can be both similar to those of routine contact correction and caused by features of mechanism of corneal refraction change as a result of OKL wear. In our opinion efficacy and safety of this option is directly depends on the correct lens fitting, patient's compliance and regular monitoring of corneal changes.

Corneal status in primary angle-closure glaucoma with a history of acute attack.

PubMed

Chen, Mei-Ju; Liu, Catherine Jui-Ling; Cheng, Ching-Yu; Lee, Shui-Mei

2012-01-01

The corneal status of patients with primary angle-closure glaucoma (PACG) with a history of acute attack was investigated. This cross-sectional study included 40 eyes of PACG patients with an earlier documented symptomatic acute angle-closure attack (aPACG), 40 uninvolved fellow eyes of aPACG patients (fPACG), 44 eyes of chronic PACG patients without such a history (cPACG), and 50 eyes of age-matched normal participants. All glaucoma patients had patent peripheral iridotomies with adequate intraocular pressure control. The examinations and recorded parameters included visual acuity, intraocular pressure, gonioscopy, vertical cup-to-disc ratio, specular microscopy, central corneal pachymetry, refraction, corneal curvature radius, anterior chamber depth, axial length, and lens thickness measurements, and the presenting intraocular pressure and the duration of acute angle-closure attack for aPACG eyes. The mean endothelial cell density was 2271±80 cells/mm(2) in aPACG, 2458±79 cells/mm(2) in fPACG, 2379±50 cells/mm(2) in cPACG, and 2559±45 cells/mm(2) in controls. The aPACG eyes had significantly lower endothelial cell density compared with normal eyes (P=0.002). There was no significant difference in endothelial cell density of aPACG eyes compared with fPACG or cPACG eyes. Multivariate analysis showed the duration of the acute attack was the only factor independently associated with corneal endothelial density of aPACG eyes. The mean central corneal thickness of aPACG (549±32 μm) did not differ significantly from control eyes (552±27 μm), cPACG (557±32 μm), and fPACG (553±31 μm) (P=0.911, 0.274, and 0.725, respectively). Corneal curvature radius of aPACG eyes was not significantly different from that of the comparison groups (all P>0.05). Corneal endothelial cell density was significantly reduced in aPACG eyes compared with normal eyes. No significant difference in endothelial cell density of aPACG eyes was noted when compared with fPACG or cPACG eyes. Corneal endothelial cell density was negatively associated with the duration of the acute attack, but was not associated with demographic and biometric characteristics. Central corneal thickness and corneal curvature radius were not associated with an earlier acute angle-closure attack.

Central corneal thickness measurements in unoperated eyes and eyes after PRK for myopia using Pentacam, Orbscan II, and ultrasonic pachymetry.

PubMed

Kim, Sun Woong; Byun, Yeo Jue; Kim, Eung Kweon; Kim, Tae-im

2007-11-01

To compare central corneal thickness measurements obtained in unoperated eyes and eyes after myopic photorefractive keratectomy (PRK) using a rotating Scheimpflug camera (Pentacam), a scanning slit corneal topography system (Orbscan II), and ultrasonic pachymetry. Corneal thickness was measured using Pentacam, Orbscan II, and ultrasonic pachymetry in 25 unoperated eyes (unoperated group), 24 eyes 1 to 3 months after myopic PRK (early postoperative PRK group), and 21 eyes 4 months or more after myopic PRK (late postoperative PRK group). In the unoperated group, corneal thickness measurements were similar for all three methods (P=.125). In the early postoperative PRK group, Orbscan measurements were thinner than Pentacam and ultrasonic measurements by a mean of 69.4 microm and 63.4 microm (P<.001 and P=.002, respectively). In the late postoperative PRK group, Orbscan measurements were thinner than Pentacam measurements by a mean of 36.0 microm (P=.017). Pentacam and ultrasonic pachymetry measurements were similar for all three groups with a mean difference of approximately 10 microm. Following myopic PRK, Pentacam was comparable to ultrasonic pachymetry in measuring corneal thickness, whereas Orbscan measurements were thinner.

Confocal Comparison of Corneal Reinnervation after Small Incision Lenticule Extraction (SMILE) and Femtosecond Laser In Situ Keratomileusis (FS-LASIK)

PubMed Central

Qin, Bing; Zhou, Zimei; Ni, Katherine; Le, Qihua; Xiang, Jun; Wei, Anji; Ma, Weiping; Zhou, Xingtao

2013-01-01

Purpose To evaluate corneal reinnervation, and the corresponding corneal sensitivity and keratocyte density after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK). Methods In this prospective, non-randomized observational study, 18 patients (32 eyes) received SMILE surgery, and 22 patients (42 eyes) received FS-LASIK surgery to correct myopia. The corneal subbasal nerve density and microscopic morphological changes in corneal architecture were evaluated by confocal microscopy prior to surgery and at 1 week, 1 month, 3 months, and 6 months after surgery. A correlation analysis was performed between subbasal corneal nerve density and the corresponding keratocyte density and corneal sensitivity. Results The decrease in subbasal nerve density was less severe in SMILE-treated eyes than in FS-LASIK-treated eyes at 1 week (P = 0.0147), 1 month (P = 0.0243), and 3 months (P = 0.0498), but no difference was detected at the 6-month visit (P = 0.5277). The subbasal nerve density correlated positively with central corneal sensitivity in both groups (r = 0.416, P<0.0001, and r = 0.2567, P = 0.0038 for SMILE group and FS-LASIK group, respectively). The SMILE-treated eyes have a lower risk of developing peripheral empty space with epithelial cells filling in (P = 0.0005). Conclusions The decrease in subbasal nerve fiber density was less severe in the SMILE group than the FS-LASIK group in the first 3 months following the surgeries. The subbasal nerve density was correlated with central corneal sensitivity. PMID:24349069

Confocal comparison of corneal reinnervation after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK).

PubMed

Li, Meiyan; Niu, Lingling; Qin, Bing; Zhou, Zimei; Ni, Katherine; Le, Qihua; Xiang, Jun; Wei, Anji; Ma, Weiping; Zhou, Xingtao

2013-01-01

To evaluate corneal reinnervation, and the corresponding corneal sensitivity and keratocyte density after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK). In this prospective, non-randomized observational study, 18 patients (32 eyes) received SMILE surgery, and 22 patients (42 eyes) received FS-LASIK surgery to correct myopia. The corneal subbasal nerve density and microscopic morphological changes in corneal architecture were evaluated by confocal microscopy prior to surgery and at 1 week, 1 month, 3 months, and 6 months after surgery. A correlation analysis was performed between subbasal corneal nerve density and the corresponding keratocyte density and corneal sensitivity. The decrease in subbasal nerve density was less severe in SMILE-treated eyes than in FS-LASIK-treated eyes at 1 week (P = 0.0147), 1 month (P = 0.0243), and 3 months (P = 0.0498), but no difference was detected at the 6-month visit (P = 0.5277). The subbasal nerve density correlated positively with central corneal sensitivity in both groups (r = 0.416, P<0.0001, and r = 0.2567, P = 0.0038 for SMILE group and FS-LASIK group, respectively). The SMILE-treated eyes have a lower risk of developing peripheral empty space with epithelial cells filling in (P = 0.0005). The decrease in subbasal nerve fiber density was less severe in the SMILE group than the FS-LASIK group in the first 3 months following the surgeries. The subbasal nerve density was correlated with central corneal sensitivity.

Different patterns of collagen-proteoglycan interaction: a scanning electron microscopy and atomic force microscopy study.

PubMed

Raspanti, M; Congiu, T; Alessandrini, A; Gobbi, P; Ruggeri, A

2000-01-01

The extracellular matrix of unfixed, unstained rat corneal stroma, visualized with high-resolution scanning electron microscopy and atomic force microscopy after minimal preliminary treatment, appears composed of straight, parallel, uniform collagen fibrils regularly spaced by a three-dimensional, irregular network of thin, delicate proteoglycan filaments. Rat tail tendon, observed under identical conditions, appears instead made of heterogeneous, closely packed fibrils interwoven with orthogonal proteoglycan filaments. Pre-treatment with cupromeronic blue just thickens the filaments without affecting their spatial layout. Digestion with chondroitinase ABC rids the tendon matrix of all its interconnecting filaments while the corneal stroma architecture remains virtually unaffected, its fibrils always being separated by an evident interfibrillar spacing which is never observed in tendon. Our observations indicate that matrix proteoglycans are responsible for both the highly regular interfibrillar spacing which is distinctive of corneal stroma, and the strong interfibrillar binding observed in tendon. These opposite interaction patterns appear to be distinctive of different proteoglycan species. The molecular details of proteoglycan interactions are still incompletely understood and are the subject of ongoing research.

Scheimpflug imaged corneal changes on anterior and posterior surfaces after collagen cross-linking

PubMed Central

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

2014-01-01

AIM To compare the anterior and posterior corneal parameters before and after collagen cross-linking therapy for keratoconus. METHODS Collagen cross-linking was performed in 31 eyes of 31 keratoconus patients (mean age 30.6±8.9y). Prior to treatment and an average 7mo after therapy, Scheimpflug analysis was performed using Pentacam HR. In addition to corneal thickness assessments, corneal radius, elevation, and aberrometric measurements were performed both on anterior and posterior corneal surfaces. Data obtained before and after surgery were statistically analyzed. RESULTS In terms of horizontal and vertical corneal radius, and central corneal thickness no deviations were observed an average 7mo after operation. Corneal higher order aberration showed no difference neither on anterior nor on posterior corneal surfaces. During follow-up period, no significant deviation was detected regarding elevation values obtained by measurement in mm units between the 3.0-8.0 mm-zones. CONCLUSION Corneal stabilization could be observed in terms of anterior and posterior corneal surfaces, elevation and higher order aberration values 7mo after collagen cross-linking therapy for keratoconus. PMID:24790876

New screening methods for donor eye-bank eyes.

PubMed

Terry, M A; Ousley, P J

1999-07-01

Current methods of screening donor eyes for corneal transplantation are not always effective in excluding corneas with abnormal topography. We used the Orbscan to determine whether corneal-thickness maps could be used as a technique for donor tissue screening. Forty eye-bank eyes were measured with the Orbscan, and a corneal-thickness map was generated. Average central pachymetry measurements from each map were compared with the thinnest midperipheral thickness reading. Two eyes from a donor who had photorefractive keratectomy (PRK) and two eyes from a donor with keratoconus were then compared with the normal donor eye results. The average difference between the thinnest midperipheral pachymetry and the central pachymetry in the control group was 0.040 +/- 0.026 mm. The eyes from the donor with PRK showed larger disparities between the central and midperipheral thicknesses because of the thinned central cornea, with differences of 0.154 mm in the right eye and 0.106 mm in the left eye. The eyes from the donor with keratoconus had midperipheral corneas that were thinner than the center, indicating eccentric, ectatic cones. The differences in thickness between the center and midperiphery in the eyes from the donor with PRK and the donor with keratoconus differed from the control group by >2 SD. Diseases or surgery that affect the relationship between the central and midperipheral corneal thickness may be screened through Orbscan pachymetry mapping with comparison with a normal range.

Central Corneal Thickness in Children

PubMed Central

2011-01-01

Objective To report the central corneal thickness (CCT) in healthy white, African-American, and Hispanic children from birth to 17 years of age. Design Prospective observational multicenter study. Central corneal thickness was measured with a hand-held contact pachymeter. Results Two thousand seventy-nine children were included in the study, with ages ranging from day of birth to 17 years. Included were 807 white, 494 Hispanic, and 474 African-American individuals, in addition to Asian, unknown and mixed race individuals. African-American children had thinner corneas on average than that of both white (p< .001) and Hispanic children (p< .001) by approximately 20 micrometers. Thicker median CCT was observed with each successive year of age from age 1 to 11 years, with year-to-year differences steadily decreasing and reaching a plateau after age 11 at 573 micrometers in white and Hispanic children and 551 micrometers in African-American children. For every 100 micrometers of thicker CCT measured, the intraocular pressure was 1.5 mmHg higher on average (p< 0.001). For every diopter of increased myopic refractive error (p< 0.001) CCT was 1 micrometer thinner on average. Conclusions Median CCT increases with age from 1 to 11 years with the greatest increase present in the youngest age groups. African-American children on average have thinner central corneas than white and Hispanic children, while white and Hispanic children demonstrate similar central corneal thickness. PMID:21911662

Ocular manifestations of Marfan syndrome in children and adolescents.

PubMed

Salchow, Daniel J; Gehle, Petra

2018-03-01

To study ocular manifestations of Marfan syndrome in children and adolescents. Retrospective comparative cohort study on consecutive patients up to age 17 years, presenting to the interdisciplinary Marfan clinic of Charité-University Medicine Berlin over a period of 4 years. A total of 52 Marfan syndrome patients and 73 controls were enrolled. In Marfan syndrome eyes, the cornea was flatter (mean keratometry, 40.86 ± 2.13 vs 42.55 ± 1.55 diopters in control eyes, p < .001) and corneal astigmatism was greater (1.50 ± 1.22 vs 0.88 ± 0.49 diopters in control eyes, p < .001). The central cornea was thinner in Marfan syndrome eyes (537.35 ± 40.64 vs 552.95 ± 38.57 μm, p = 0.007) and Marfan syndrome eyes were more myopic than control eyes (spherical equivalent, -2.77 ± 4.77 vs -0.64 ± 1.92 diopters, p < .001). Visual acuity was reduced (logMAR 0.11 ± 0.17 vs 0.04 ± 0.26, p = 0.014) and intraocular pressure was lower in Marfan syndrome eyes. Iris transillumination defects were more common in Marfan syndrome eyes (19.6% vs 4.3% in control eyes, odds ratio for Marfan syndrome in the presence of iris transillumination defects = 7.2). Ectopia lentis was only found in Marfan syndrome eyes (25 Marfan syndrome patients, 49% with available data, bilateral in 68%). Iris transillumination defects and ectopia lentis are characteristic ocular findings in children and adolescents with Marfan syndrome. Myopia is more common and corneal curvature, central corneal thickness, and visual acuity are reduced in Marfan syndrome eyes. Children with Marfan syndrome need regular comprehensive eye examinations to identify potential complications.

Topical administration of orbital fat-derived stem cells promotes corneal tissue regeneration.

PubMed

Lin, Ko-Jo; Loi, Mei-Xue; Lien, Gi-Shih; Cheng, Chieh-Feng; Pao, Hsiang-Yin; Chang, Yun-Chuang; Ji, Andrea Tung-Qian; Ho, Jennifer Hui-Chun

2013-06-14

Topical administration of eye drops is the major route for drug delivery to the cornea. Orbital fat-derived stem cells (OFSCs) possess an in vitro corneal epithelial differentiation capacity. Both the safety and immunomodulatory ability of systemic OFSC transplantation were demonstrated in our previous work. In this study, we investigated the safety, therapeutic effect, and mechanism(s) of topical OFSC administration in an extensive alkali-induced corneal wound. Corneal injury was created by contact of a piece of 0.5 N NaOH-containing filter paper on the corneal surface of a male Balb/c mouse for 30 s. The area of the filter paper covered the central 70% or 100% of the corneal surface. OFSCs (2 × 10(5)) in 5 μl phosphate-buffered saline (PBS) were given by topical administration (T) twice a day or by two intralimbal (IL) injections in the right cornea, while 5 μl of PBS in the left cornea served as the control. Topical OFSCs promoted corneal re-epithelialization of both the limbal-sparing and limbal-involved corneal wounds. In the first three days, topical OFSCs significantly reduced alkali-induced corneal edema and stromal infiltration according to a histopathological examination. Immunohistochemistry and immunofluorescence staining revealed that transplanted cells were easily detectable in the corneal epithelium, limbal epithelium and stroma, but only some of transplanted cells at the limbal epithelium had differentiated into cytokeratin 3-expressing cells. OFSCs did not alter neutrophil (Ly6G) levels in the cornea, but significantly reduced macrophage (CD68) infiltration and inducible nitrous oxide synthetase (iNOS) production during acute corneal injury as quantified by a Western blot analysis. Continuous topical administration of OFSCs for seven days improved corneal transparency, and this was accompanied by diffuse stromal engraftment of transplanted cells and differentiation into p63-expressing cells at the limbal area. The therapeutic effect of the topical administration of OFSCs was superior to that of the IL injection. OFSCs from the IL injection clustered in the limbal area and central corneal epithelium, which was associated with a persistent corneal haze. Topical OFSC administration is a simple, non-surgical route for stem cell delivery to promote corneal tissue regeneration through ameliorating acute inflammation and corneal epithelial differentiation. The limbal area serves as a niche for OFSCs differentiating into corneal epithelial cells in the first week, while the stroma is a potential site for anti-inflammation of OFSCs. Inhibition of corneal inflammation is related to corneal transparency.

Topical administration of orbital fat-derived stem cells promotes corneal tissue regeneration

PubMed Central

2013-01-01

Introduction Topical administration of eye drops is the major route for drug delivery to the cornea. Orbital fat-derived stem cells (OFSCs) possess an in vitro corneal epithelial differentiation capacity. Both the safety and immunomodulatory ability of systemic OFSC transplantation were demonstrated in our previous work. In this study, we investigated the safety, therapeutic effect, and mechanism(s) of topical OFSC administration in an extensive alkali-induced corneal wound. Methods Corneal injury was created by contact of a piece of 0.5 N NaOH-containing filter paper on the corneal surface of a male Balb/c mouse for 30 s. The area of the filter paper covered the central 70% or 100% of the corneal surface. OFSCs (2 × 105) in 5 μl phosphate-buffered saline (PBS) were given by topical administration (T) twice a day or by two intralimbal (IL) injections in the right cornea, while 5 μl of PBS in the left cornea served as the control. Results Topical OFSCs promoted corneal re-epithelialization of both the limbal-sparing and limbal-involved corneal wounds. In the first three days, topical OFSCs significantly reduced alkali-induced corneal edema and stromal infiltration according to a histopathological examination. Immunohistochemistry and immunofluorescence staining revealed that transplanted cells were easily detectable in the corneal epithelium, limbal epithelium and stroma, but only some of transplanted cells at the limbal epithelium had differentiated into cytokeratin 3-expressing cells. OFSCs did not alter neutrophil (Ly6G) levels in the cornea, but significantly reduced macrophage (CD68) infiltration and inducible nitrous oxide synthetase (iNOS) production during acute corneal injury as quantified by a Western blot analysis. Continuous topical administration of OFSCs for seven days improved corneal transparency, and this was accompanied by diffuse stromal engraftment of transplanted cells and differentiation into p63-expressing cells at the limbal area. The therapeutic effect of the topical administration of OFSCs was superior to that of the IL injection. OFSCs from the IL injection clustered in the limbal area and central corneal epithelium, which was associated with a persistent corneal haze. Conclusions Topical OFSC administration is a simple, non-surgical route for stem cell delivery to promote corneal tissue regeneration through ameliorating acute inflammation and corneal epithelial differentiation. The limbal area serves as a niche for OFSCs differentiating into corneal epithelial cells in the first week, while the stroma is a potential site for anti-inflammation of OFSCs. Inhibition of corneal inflammation is related to corneal transparency. PMID:23769140

Optical coherence tomography-based topography determination of corneal grafts in eye bank cultivation

NASA Astrophysics Data System (ADS)

Damian, Angela; Seitz, Berthold; Langenbucher, Achim; Eppig, Timo

2017-01-01

Vision loss due to corneal injuries or diseases can be treated by transplantation of human corneal grafts (keratoplasty). However, quality assurance in retrieving and cultivating the tissue transplants is confined to visual and microbiological testing. To identify previous refractive surgery or morphological alterations, an automatic, noncontact, sterile screening procedure is required. Twenty-three corneal grafts have been measured in organ culture with a clinical spectral-domain optical coherence tomographer. Employing a biconic surface fit with 10 degrees of freedom, the radii of curvature and conic constants could be estimated for the anterior and posterior corneal surfaces. Thereupon, central corneal thickness, refractive values, and astigmatism have been calculated. Clinical investigations are required to elaborate specific donor-host matching in the future.

Genetics Home Reference: Meesmann corneal dystrophy

MedlinePlus

... Smith FJ, Rochels R, Uitto J, McLEAN WH. Molecular genetics of Meesmann's corneal dystrophy: ancestral and novel mutations ... Free article on PubMed Central Smith F. The molecular genetics of keratin disorders. Am J Clin Dermatol. 2003; ...

Regional repeatability measures of corneal thickness: Orbscan II and ultrasound.

PubMed

Jonuscheit, Sven; Doughty, Michael J

2007-01-01

To compare repeatability of the measures of corneal thickness obtained by slit-scanning light method (Orbscan II) with those obtained by an ultrasound pachymeter, with special interest in the peripheral region of the cornea. On 24 normal adults, aged 20 to 58 years (average 36 years) with up to -8.5 DS refractive error, three measures of corneal thickness were taken using Orbscan II and then by ultrasound pachymetry (under topical anesthesia with benoxinate 0.4%). The Orbscan central sample zone of 1 mm was selected, or the numerical maps were used to extract single point data along the horizontal corneal meridian to the nasal and temporal sides out to 4.5 mm. Ultrasound readings were taken from the central cornea and at the periphery just inside the limbus (4.5 mm from center) with a 2.4-mm diameter probe. For a central 1-mm diameter zone, the coefficient of variation (CV) for three consecutive corneal thickness measures was 0.81%+/-0.44%, but was marginally higher (p=0.004), if just the central single point data was taken with Orbscan (0.86%+/-0.45%). Similar repeatability was noted for the numerical output across the temporal side along the horizontal meridian out to 2.5 mm from the center, but farther out to 4 mm and on the nasal side the repeatability was slightly less and around 1.0% (p<0.001). Orbscan point readings of thickness could only sometimes be obtained at 4.5 mm temporally (with a poorer CV of 1.32%) and very rarely at 4.5 mm on the nasal side. No absolute differences in Orbscan repeatability were noted when comparing emmetropic with myopic subjects (p>or=0.5). Ultrasound pachymetry readings across the central zone were repeatable to 0.82%+/-0.67%. When measured with the edge of the ultrasound probe just touching the limbus, the repeatability of ultrasound readings was 1.37%+/-1.10% temporally and 1.49%+/-1.02% nasally, but neither was statistically worse that the most peripheral readings for Orbscan (p>or=0.210). However, it was also noted that the absolute values of corneal thickness, even with the application of the 0.92 acoustic factor, were 0.010 mm greater for Orbscan at the center and 0.040 mm in the corneal periphery. Orbscan II provides the clinician with a repeatable noninvasive method of measuring corneal thickness that is not necessarily any better than ultrasound pachymetry, and should not be considered as interchangeable with that for ultrasound.

Thick keratoconic cornea associated with posterior polymorphous corneal dystrophy.

PubMed

Zaarour, K; Slim, E; Antoun, J; Waked, N

2017-03-01

We herein report a case of bilateral unusually thick non-edematous keratoconic corneas with associated endothelial features of posterior polymorphous corneal dystrophy (PPCD). We report the case of a 27-year-old myopic woman who presented for refractive surgery. Slit lamp exam showed bilateral corneal protrusion with diffuse deep stromal and endothelial vesicular opacities and small paracentral bands. Topography showed generalized advanced corneal steepening in both eyes with increased anterior and posterior central corneal elevations in comparison to the best fit sphere. Ultrasound pachymetry showed central corneal thickness of 605μm (RE) and 612μm (LE). On specular biomicroscopy, cell density of 2503 cells/mm 2 RE and 1526 cells/mm 2 LE with significant cellular pleomorphism and polymegathism were noted. Clinical and paraclinical findings together suggest the presence of simultaneous keratoconus and PPCD. The literature has suggested an association between PPCD and steep cornea. Moreover, many reports have also described cases of associated PPCD and keratoconus with characteristic thinning and ectasia, in comparison to the unusual thick corneas noted in our patient, despite the absence of edema. Identification of genetics factors is further needed to clarify this association. This case describes a patient whose corneas present features of both keratoconus and PPCD and is unique due to the presence of increased corneal thickness despite the absence of edema. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Long-term follow-up of astigmatic keratotomy for corneal astigmatism after penetrating keratoplasty.

PubMed

Böhringer, Daniel; Dineva, Nina; Maier, Philip; Birnbaum, Florian; Kirschkamp, Thomas; Reinhard, Thomas; Eberwein, Philipp

2016-11-01

To report the long-term stability of paired arcuate corneal keratotomies (AKs) in patients with high regular postpenetrating keratoplasty astigmatism. Retrospective chart review of best-corrected visual acuity, refraction and keratometric values of 41 eyes with AK between 2003 and 2012. Magnitude of median target induced astigmatism vector was 9.2 dioptres (Dpt). We reached a median magnitude of surgically induced astigmatism vector of 9.81 Dpt and a median magnitude of difference vector of 5.5 Dpt. In keratometry, we achieved a net median astigmatism reduction by 3.3 Dpt. The average correction index was 1.14, showing a slight overcorrection. Irregularity of keratometric astigmatism increased by 0.6 Dpt, and spherical equivalent changed by 1.75 Dpt. Monocular best spectacle corrected visual acuity increased from preoperatively 20/63 (0.5 logMAR) to 20/40 (0.3 logMAR) postoperatively. Median gain on the ETDRS chart was two lines. Long-term follow-up showed a median keratometric astigmatic increase by 0.3 Dpt per year. Arcuate corneal keratotomies is a safe and effective method to reduce high regular corneal astigmatism following penetrating keratoplasty but has limited predictability. The long-term follow-up shows an increase of keratometric astigmatism by 0.3 Dpt/year, equalizing the surgical effect after 10 years. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Designing multifocal corneal models to correct presbyopia by laser ablation

NASA Astrophysics Data System (ADS)

Alarcón, Aixa; Anera, Rosario G.; Del Barco, Luis Jiménez; Jiménez, José R.

2012-01-01

Two multifocal corneal models and an aspheric model designed to correct presbyopia by corneal photoablation were evaluated. The design of each model was optimized to achieve the best visual quality possible for both near and distance vision. In addition, we evaluated the effect of myosis and pupil decentration on visual quality. The corrected model with the central zone for near vision provides better results since it requires less ablated corneal surface area, permits higher addition values, presents stabler visual quality with pupil-size variations and lower high-order aberrations.

Effect of Autologous Serum Eye Drops in Patients with Sjögren Syndrome-related Dry Eye: Clinical and In Vivo Confocal Microscopy Evaluation of the Ocular Surface.

PubMed

Semeraro, Francesco; Forbice, Eliana; Nascimbeni, Giuseppe; Taglietti, Marco; Romano, Vito; Guerra, Germano; Costagliola, Ciro

To evaluate in vivo changes after therapy using autologous serum (AS) eye drops in Sjögren's syndrome (SS)-related dry eyes by confocal microscopy. In this study, 24 patients with SS-related dry eyes [12 in AS eye drop therapy and 12 in artificial tear (AT) therapy] and 24 healthy volunteers were recruited. Ocular Surface Disease Index (OSDI), central corneal thickness, tear film, break-up time, corneal and conjunctival staining, Schirmer's test and corneal confocal microscopy were investigated. Tear production, tear stability, corneal staining, inflammation, and central corneal thickness, Langherans cells, activated keratocytes, intermediate epithelial cell density, nerve tortuosity, number of sub-basal nerve branches, and number of bead-like formations differed between patients and controls (p<0.0001). The AT and AS groups differed in the OSDI, number of branches, and number of beadings (p<0.0001). AS eye drops improve symptoms and confocal microscopy findings in SS-related dry eyes. Copyright © 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

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

Morishige, Naoyuki; Ko, Ji-Ae, E-mail: jiae0831@yamaguchi-u.ac.jp; Morita, Yukiko

The neural guidance protein semaphorin 3A (Sema3A) is expressed in corneal epithelial cells of the adult rat. We have now further investigated the localization of Sema3A in the normal rat corneal epithelium as well as changes in its expression pattern during wound healing after central corneal epithelial debridement. The expression pattern of Sema3A was compared with that of the tight-junction protein zonula occludens-1 (ZO-1), the gap-junction protein connexin43 (Cx43), or the cell proliferation marker Ki67. Immunofluorescence analysis revealed that Sema3A was present predominantly in the membrane of basal and wing cells of the intact corneal epithelium. The expression of Sema3Amore » at the basal side of basal cells was increased in the peripheral epithelium compared with that in the central region. Sema3A was detected in all layers at the leading edge of the migrating corneal epithelium at 6 h after central epithelial debridement. The expression of Sema3A was markedly up-regulated in the basal and lateral membranes of columnar basal cells apparent in the thickened, newly healed epithelium at 1 day after debridement, but it had largely returned to the normal pattern at 3 days after debridement. The expression of ZO-1 was restricted to superficial epithelial cells and remained mostly unchanged during the wound healing process. The expression of Cx43 in basal cells was down-regulated at the leading edge of the migrating epithelium but was stable in the remaining portion of the epithelium. Ki67 was not detected in basal cells of the central epithelium at 1 day after epithelial debridement, when Sema3A was prominently expressed. Immunoblot analysis showed that the abundance of Sema3A in the central cornea was increased 1 day after epithelial debridement, whereas that of ZO-1 or Cx43 remained largely unchanged. This increase in Sema3A expression was accompanied by up-regulation of the Sema3A coreceptor neuropilin-1. Our observations have thus shown that the expression of Sema3A is increased markedly in basal cells of the newly healed corneal epithelium, and that this up-regulation of Sema3A is not associated with cell proliferation. They further suggest that Sema3A might play a role in the regulation of corneal epithelial wound healing.« less

Repeatability and reproducibility of corneal thickness using SOCT Copernicus HR.

PubMed

Vidal, Silvia; Viqueira, Valentín; Mas, David; Domenech, Begoña

2013-05-01

The aim of this study is to determine the reliability of corneal thickness measurements derived from SOCT Copernicus HR (Fourier domain OCT). Thirty healthy eyes of 30 subjects were evaluated. One eye of each patient was chosen randomly. Images were obtained of the central (up to 2.0 mm from the corneal apex) and paracentral (2.0 to 4.0 mm) cornea. We assessed corneal thickness (central and paracentral) and epithelium thickness. The intra-observer repeatability data were analysed using the intra-class correlation coefficient (ICC) for a range of 95 per cent within-subject standard deviation (S(W)) and the within-subject coefficient of variation (C(W)). The level of agreement by Bland-Altman analysis was also represented for the study of the reproducibility between observers and agreement between methods of measurement (automatic versus manual). The mean value of the central corneal thickness (CCT) was 542.4 ± 30.1 μm (SD). There was a high intra-observer agreement, finding the best result in the central sector with an intra-class correlation coefficient of 0.99, 95 per cent CI (0.989 to 0.997) and the worst, in the minimum corneal thickness, with an intra-class correlation coefficient of 0.672, 95 per cent CI (0.417 to 0.829). Reproducibility between observers was very high. The best result was found in the central sector thickness obtained both manually and automatically with an intra-class correlation coefficient of 0.990 in both cases and the worst result in the maximum corneal thickness with an intra-class correlation coefficient of 0.827. The agreement between measurement methods was also very high with intra-class correlation coefficient greater than 0.91. On the other hand the repeatability and reproducibility for epithelial measurements was poor. Pachymetric mapping with SOCT Copernicus HR was found to be highly repeatable and reproducible. We found that the device lacks an appropriate ergonomic design as proper focusing of the laser beam onto the cornea for anterior segment scanning required that patients were positioned slightly farther away from the machine head-rest than in the setup for retinal imaging. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

Postoperative corneal shape changes: microincision versus small-incision coaxial cataract surgery.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Hayashi, Hideyuki

2009-02-01

To compare changes in corneal topography and in regular and irregular astigmatism after coaxial clear corneal microincision cataract surgery (MICS) and after coaxial small-incision cataract surgery (SICS). Hayashi Eye Hospital, Fukuoka, Japan. Induced corneal astigmatism was determined using vector analysis. The averaged corneal shape changes and degree of irregular astigmatism were examined using videokeratography preoperatively as well as 2 days and 1, 2, 4, and 8 weeks postoperatively. One hundred twenty eyes of 60 patients scheduled for phacoemulsification were evaluated. Sixty eyes had MICS (2.00 mm), and the 60 contralateral eyes had SICS (2.65 mm). The mean induced corneal astigmatism was significantly less in the MICS group than in the SICS group (P

Corneal Confocal Microscopy Detects Corneal Nerve Damage in Patients Admitted With Acute Ischemic Stroke.

PubMed

Khan, Adnan; Akhtar, Naveed; Kamran, Saadat; Ponirakis, Georgios; Petropoulos, Ioannis N; Tunio, Nahel A; Dargham, Soha R; Imam, Yahia; Sartaj, Faheem; Parray, Aijaz; Bourke, Paula; Khan, Rabia; Santos, Mark; Joseph, Sujatha; Shuaib, Ashfaq; Malik, Rayaz A

2017-11-01

Corneal confocal microscopy can identify corneal nerve damage in patients with peripheral and central neurodegeneration. However, the use of corneal confocal microscopy in patients presenting with acute ischemic stroke is unknown. One hundred thirty patients (57 without diabetes mellitus [normal glucose tolerance], 32 with impaired glucose tolerance, and 41 with type 2 diabetes mellitus) admitted with acute ischemic stroke, and 28 age-matched healthy control participants underwent corneal confocal microscopy to quantify corneal nerve fiber density, corneal nerve branch density, and corneal nerve fiber length. There was a significant reduction in corneal nerve fiber density, corneal nerve branch density, and corneal nerve fiber length in stroke patients with normal glucose tolerance ( P <0.001, P <0.001, P <0.001), impaired glucose tolerance ( P =0.004, P <0.001, P =0.002), and type 2 diabetes mellitus ( P <0.001, P <0.001, P <0.001) compared with controls. HbA1c and triglycerides correlated with corneal nerve fiber density ( r =-0.187, P =0.03; r =-0.229 P =0.01), corneal nerve fiber length ( r =-0.228, P =0.009; r =-0.285; P =0.001), and corneal nerve branch density ( r =-0.187, P =0.033; r =-0.229, P =0.01). Multiple linear regression showed no independent associations between corneal nerve fiber density, corneal nerve branch density, and corneal nerve fiber length and relevant risk factors for stroke. Corneal confocal microscopy is a rapid noninvasive ophthalmic imaging technique that identifies corneal nerve fiber loss in patients with acute ischemic stroke. © 2017 American Heart Association, Inc.

Morphology of the Corneal Limbus Following Standard and Accelerated Corneal Collagen Cross-Linking (9 mW/cm2) for Keratoconus.

PubMed

Uçakhan, Ömür Ö; Bayraktutar, Betül

2017-01-01

To evaluate the morphological features of the corneal limbus as measured by in vivo confocal microscopy (IVCM) following standard and accelerated corneal collagen cross-linking (CXL) for keratoconus. Patients with progressive keratoconus scheduled to undergo standard CXL (group 1; 31 patients, 3 mW/cm, 370 nm, 30 minutes), or accelerated CXL (group 2; 20 patients, 9 mW/cm, 370 nm, 10 minutes) in the worse eye were included in this prospective study. Thirty eyes of 30 age-matched patients served as controls (group 3). All patient eyes underwent IVCM scanning of the central cornea and the inferior limbal area at baseline and 1, 3, and 6 months after CXL. After CXL, epithelial regrowth was complete by day 4 in both groups 1 and 2. There were no statistically significant differences between the baseline mean central corneal wing or basal cell density, limbus-palisade middle or basal cell densities of groups 1, 2, or 3. At postoperative months 1, 3, and 6, there were no statistically significant differences in either central or limbus-palisade epithelial cell densities or diameters in keratoconic eyes that underwent standard or accelerated CXL (P > 0.05). The morphology of the limbal cells was preserved as well. The morphology of limbus structures seems to be preserved following standard and accelerated CXL in short-term follow-up, as measured using IVCM.

Quantitative OCT-based longitudinal evaluation of intracorneal ring segment implantation in keratoconus.

PubMed

Pérez-Merino, Pablo; Ortiz, Sergio; Alejandre, Nicolas; Jiménez-Alfaro, Ignacio; Marcos, Susana

2013-09-09

To characterize the geometrical properties of keratoconic corneas upon intracorneal ring segments (ICRS) implantation, using custom-developed optical coherence tomography (OCT). Ten keratoconic corneas were measured pre- and post-ICRS surgery (7, 30, and 90 days). Corneal topographic and pachymetric maps were obtained from three-dimensional (3D) images acquired with OCT, provided with custom algorithms for image analysis, distortion correction, and quantification. The 3D positioning of the ICRS was also estimated longitudinally, relative to the pupil center and iris plane. Preoperatively, the average corneal radii of curvature were 7.02 ± 0.54 mm (anterior) and 5.40 ± 0.77 mm (posterior), and the minimum corneal thickness was 384 ± 60 μm. At 90 days, the average corneal radii of curvature were 7.26 ± 0.53 mm (anterior) and 5.44 ± 0.71 mm (posterior), and the minimum corneal thickness was 396 ± 46 μm. ICRS implantation produced a significant decrease of corneal power (by 1.71 ± 1.83 diopters [D] at 90 days). Corneal irregularities (defined by high order Zernike terms of the corneal elevation maps) and the corneal thickness distribution decreased in some patients and increased in others. The 3D ICRS depth matched the planned ICRS depth well (within 23.93 ± 23.49 μm). On average, ICRS showed an overall tilt of -6.8 ± 2.6° (temporal) and -2.1 ± 0.8° (superior) at 7 days. Spectral OCT (sOCT) provided with distortion correction and analysis tools, is an excellent instrument for evaluating the changes produced by ICRS in keratoconic corneas, and for analyzing the 3D ICRS position during the follow up. ICRS produced flattening on the anterior corneal surface, although the benefit for corneal surface regularization varied across patients.

Stromal demarcation line induced by corneal cross-linking in eyes with keratoconus and nonkeratoconic asymmetric topography.

PubMed

Malta, João B N; Renesto, Adimara C; Moscovici, Bernardo K; Soong, H K; Campos, Mauro

2015-02-01

To evaluate stromal demarcation lines following corneal cross-linking (CXL) using anterior segment optical coherence tomography in patients with keratoconus and nonkeratoconic asymmetric topography. Fifth-nine eyes of 59 patients were enrolled in a retrospective comparative case series, of which 19 eyes had keratoconus and 40 eyes had asymmetric topography. Eyes with asymmetric topography were treated in preparation for photorefractive keratectomy. One month after CXL, a stromal demarcation line was evaluated at 5 standardized corneal points using anterior segment optical coherence tomography. Mean stromal demarcation line depths were measured at 5 points on the cornea, namely, centrally, 3.0 mm temporally, 1.5 mm temporally, 3.0 mm nasally, and 1.5 mm nasally. For the keratoconus group, the values were 178 ± 47, 123 ± 15, 152 ± 47, 125 ± 23, and 160 ± 43 μm, respectively. For the asymmetric corneal topography group (without keratoconus), they were 305 ± 64, 235 ± 57, 294 ± 50, 214 ± 54, and 285 ± 58 μm, respectively. There was no correlation between central corneal pachymetry and stromal demarcation line depth in all 5 measured corneal points in both groups. CXL treatment profiles are similar in keratoconic and nonkeratoconic eyes with asymmetric topography.

Induced videokeratography alterations in patients with excessive meibomian secretions.

PubMed

Markomanolakis, Marinos M; Kymionis, George D; Aslanides, Ioannis M; Astyrakakis, Nikolaos; Pallikaris, Ioannis G

2005-01-01

To describe lipid-induced specific videokeratographic (VKG) corneal changes and subsequent resolution after eyelid washing. VKG was performed with C-Scan corneal topography. In all patients an excessive meibomian gland lipid secretion was found with or without coexistent chronic posterior blepharitis. After the initial VKG, a meticulous cleaning of the lids with a mild alkali shampoo (10% Johnson's baby shampoo in sterile water) was done, first by gently scrubbing the closed eyelid fissure with the solution to mobilize and emulsify any Meibomian gland secretions followed by cleaning of the upper and lower margins individually, using Q-tip applicators soaked in the detergent. Three patients with tear film lipid layer excess (TFLE), which correlated with the presence of a superior or central corneal steepening in VKG, were studied. In two of the subjects, careful lid washing reversed either completely or partially this VKG effect, whereas in the last patient the VKG changes after artificially increasing the tear film lipid content is described. Meibomian gland lipid secretions may induce mainly superior and occasionally central VKG corneal steepening that is not correlated with any slit-lamp pathologic findings. Computerized corneal topography can help detect such corneal abnormalities, and their reversibility may distinguish them from other pathologic conditions (such as contact lens-induced warpage, eccentric ablations, irregular astigmatism, superior keratoconus).

The Comparison between Torsional and Conventional Mode Phacoemulsification in Moderate and Hard Cataracts

PubMed Central

Kim, Dong-Hyun; Wee, Won-Ryang; Lee, Jin-Hak

2010-01-01

Purpose To compare the intraoperative performances and postoperative outcomes of cataract surgery performed with longitudinal phacoemulsification and torsional phacoemulsification in moderate and hard cataracts. Methods Of 85 patients who had senile cataracts, 102 eyes were operated on using the Infiniti Vision System. Preoperative examinations (slit lamp examination, mean central corneal thickness, and central endothelial cell counts) were performed for each patient. Cataracts were subdivided into moderate and hard, according to the Lens Opacities Classification System III grading of nucleus opalescence (NO). Eyes in each cataract group were randomly assigned to conventional and torsional phaco-mode. Intraoperative parameters, including ultrasound time (UST), cumulative dissipated energy (CDE), and the balanced salt solution plus (BSSP) volume utilized were evaluated. Best corrected visual acuity (BCVA) was checked on postoperative day 30; mean central corneal thickness and central endothelial cell counts were investigated on postoperative days 7 and 30. Results Preoperative BCVA and mean grading of NO showed no difference in both groups. Preoperative endothelial cell count and central corneal thickness also showed no significant difference in both groups. In the moderate cataract group, the CDE, UST, and BSSP volume were significantly lower in the torsional mode than the longitudinal mode, but they did not show any difference in the hard cataract group. Torsional group showed less endothelial cell loss and central corneal thickening at postoperative day seven in moderate cataracts but showed no significant differences, as compared with the longitudinal group, by postoperative day 30. Conclusions Torsional phacoemulsification showed superior efficiency for moderate cataracts, as compared with longitudinal phacoemulsification, in the early postoperative stage. PMID:21165231

The comparison between torsional and conventional mode phacoemulsification in moderate and hard cataracts.

PubMed

Kim, Dong-Hyun; Wee, Won-Ryang; Lee, Jin-Hak; Kim, Mee-Kum

2010-12-01

To compare the intraoperative performances and postoperative outcomes of cataract surgery performed with longitudinal phacoemulsification and torsional phacoemulsification in moderate and hard cataracts. Of 85 patients who had senile cataracts, 102 eyes were operated on using the Infiniti Vision System. Preoperative examinations (slit lamp examination, mean central corneal thickness, and central endothelial cell counts) were performed for each patient. Cataracts were subdivided into moderate and hard, according to the Lens Opacities Classification System III grading of nucleus opalescence (NO). Eyes in each cataract group were randomly assigned to conventional and torsional phaco-mode. Intraoperative parameters, including ultrasound time (UST), cumulative dissipated energy (CDE), and the balanced salt solution plus (BSSP) volume utilized were evaluated. Best corrected visual acuity (BCVA) was checked on postoperative day 30; mean central corneal thickness and central endothelial cell counts were investigated on postoperative days 7 and 30. Preoperative BCVA and mean grading of NO showed no difference in both groups. Preoperative endothelial cell count and central corneal thickness also showed no significant difference in both groups. In the moderate cataract group, the CDE, UST, and BSSP volume were significantly lower in the torsional mode than the longitudinal mode, but they did not show any difference in the hard cataract group. Torsional group showed less endothelial cell loss and central corneal thickening at postoperative day seven in moderate cataracts but showed no significant differences, as compared with the longitudinal group, by postoperative day 30. Torsional phacoemulsification showed superior efficiency for moderate cataracts, as compared with longitudinal phacoemulsification, in the early postoperative stage.

Assessment of corneal epithelial thickness in dry eye patients.

PubMed

Cui, Xinhan; Hong, Jiaxu; Wang, Fei; Deng, Sophie X; Yang, Yujing; Zhu, Xiaoyu; Wu, Dan; Zhao, Yujin; Xu, Jianjiang

2014-12-01

To investigate the features of corneal epithelial thickness topography with Fourier-domain optical coherence tomography (OCT) in dry eye patients. In this cross-sectional study, 100 symptomatic dry eye patients and 35 normal subjects were enrolled. All participants answered the ocular surface disease index questionnaire and were subjected to OCT, corneal fluorescein staining, tear breakup time, Schirmer 1 test without anesthetic (S1t), and meibomian morphology. Several epithelium statistics for each eye, including central, superior, inferior, minimum, maximum, minimum - maximum, and map standard deviation, were averaged. Correlations of epithelial thickness with the symptoms of dry eye were calculated. The mean (±SD) central, superior, and inferior corneal epithelial thickness was 53.57 (±3.31) μm, 52.00 (±3.39) μm, and 53.03 (±3.67) μm in normal eyes and 52.71 (±2.83) μm, 50.58 (±3.44) μm, and 52.53 (±3.36) μm in dry eyes, respectively. The superior corneal epithelium was thinner in dry eye patients compared with normal subjects (p = 0.037), whereas central and inferior epithelium were not statistically different. In the dry eye group, patients with higher severity grades had thinner superior (p = 0.017) and minimum (p < 0.001) epithelial thickness, more wide range (p = 0.032), and greater deviation (p = 0.003). The average central epithelial thickness had no correlation with tear breakup time, S1t, or the severity of meibomian glands, whereas average superior epithelial thickness positively correlated with S1t (r = 0.238, p = 0.017). Fourier-domain OCT demonstrated that the thickness map of the dry eye corneal epithelium was thinner than normal eyes in the superior region. In more severe dry eye disease patients, the superior and minimum epithelium was much thinner, with a greater range of map standard deviation.

Inverse cutting of posterior lamellar corneal grafts by a femtosecond laser.

PubMed

Hjortdal, Jesper; Nielsen, Esben; Vestergaard, Anders; Søndergaard, Anders

2012-01-01

Posterior lamellar grafting of the cornea has become the preferred technique for treatment of corneal endothelial dysfunction. Posterior lamellar grafts are usually cut by a micro-keratome or a femto-second laser after the epithelial side of the donor cornea has been applanated. This approach often results in variable central graft thickness in different grafts and an increase in graft thickness towards the periphery in every graft. The purpose of this study was to evaluate if posterior lamellar grafts can be prepared from the endothelial side by a femto-second laser, resulting in reproducible, thin grafts of even thickness. A CZM 500 kHz Visumax femto-second laser was used. Organ cultured donor grafts were mounted in an artifical anterior chamber with the endothelial side up and out. Posterior grafts of 7.8 mm diameter and 130 micron thickness were prepared by femto-second laser cutting. A standard DSAEK procedure was performed in 10 patients with Fuchs endothelial dystrophy. Patients were followed-up regularly and evaluated by measurement of complications, visual acuity, corneal thickness (Pentacam HR), and endothelial cell density. Femto-laser cutting of grafts and surgery was uncomplicated. Rebubbling was necessary in 5 of 10 cases (normally only in 1 of 20 cases). All grafts were attached and cleared up during the first few weeks. After six months, the average visual acuity was 0.30 (range: 0.16 to 0.50), corneal thickness was 0.58 mm (range 0.51 to 0.63), and endothelial cell density was 1.570 per sq. mm (range: 1.400 to 2.000 cells per sq. mm). The grafts were of uniform thickness, but substantial interface haze was present in most grafts. Posterior lamellar corneal grafts can be prepared from the endothelial side using a femto-second laser. All grafts were clear after 6 months with satisfying endothelial cell counts. Poor visual acuity caused by interface scatter was observed in most patients. Femto-second laser cutting parameters needs to be optimised to enable smooth cutting in the posterior stroma.

Inverse Cutting of Posterior Lamellar Corneal Grafts by a Femtosecond Laser

PubMed Central

Hjortdal, Jesper; Nielsen, Esben; Vestergaard, Anders; Søndergaard, Anders

2012-01-01

Purpose Posterior lamellar grafting of the cornea has become the preferred technique for treatment of corneal endothelial dysfunction. Posterior lamellar grafts are usually cut by a micro-keratome or a femto-second laser after the epithelial side of the donor cornea has been applanated. This approach often results in variable central graft thickness in different grafts and an increase in graft thickness towards the periphery in every graft. The purpose of this study was to evaluate if posterior lamellar grafts can be prepared from the endothelial side by a femto-second laser, resulting in reproducible, thin grafts of even thickness. Methods A CZM 500 kHz Visumax femto-second laser was used. Organ cultured donor grafts were mounted in an artifical anterior chamber with the endothelial side up and out. Posterior grafts of 7.8 mm diameter and 130 micron thickness were prepared by femto-second laser cutting. A standard DSAEK procedure was performed in 10 patients with Fuchs endothelial dystrophy. Patients were followed-up regularly and evaluated by measurement of complications, visual acuity, corneal thickness (Pentacam HR), and endothelial cell density. Results Femto-laser cutting of grafts and surgery was uncomplicated. Rebubbling was necessary in 5 of 10 cases (normally only in 1 of 20 cases). All grafts were attached and cleared up during the first few weeks. After six months, the average visual acuity was 0.30 (range: 0.16 to 0.50), corneal thickness was 0.58 mm (range 0.51 to 0.63), and endothelial cell density was 1.570 per sq. mm (range: 1.400 to 2.000 cells per sq. mm). The grafts were of uniform thickness, but substantial interface haze was present in most grafts. Conclusions Posterior lamellar corneal grafts can be prepared from the endothelial side using a femto-second laser. All grafts were clear after 6 months with satisfying endothelial cell counts. Poor visual acuity caused by interface scatter was observed in most patients. Femto-second laser cutting parameters needs to be optimised to enable smooth cutting in the posterior stroma. PMID:22582107

Time course of the effects of orthokeratology on peripheral refraction and corneal topography.

PubMed

Kang, Pauline; Swarbrick, Helen

2013-05-01

To describe the time course of changes in both peripheral refraction and corneal topography in myopic adults wearing myopic orthokeratology (OK) lenses. Nineteen adult myopes were fitted with OK lenses in both eyes for overnight wear. Central and peripheral refraction and corneal topography were measured along the horizontal meridian at baseline and after 1, 4, 7 and 14 nights of lens wear. At baseline, refraction was myopic at all positions along the horizontal meridian. Two weeks of OK lens wear caused a significant change in refraction where the general trend was a hyperopic shift in spherical equivalent (M) except at 35° in the nasal visual field where there was instead a myopic shift in M. The most significant change in M occurred between baseline and after 1 night of OK lens wear and the effect became less dramatic across subsequent days of OK treatment. Similarly, OK caused significant change in corneal refractive power at all positions along the horizontal corneal chord. There was a reduction in corneal power or flattening of the cornea at all positions except at 2.4 mm and 2.8 mm on the nasal cornea where there was an increase in corneal refractive power or steepening of the cornea. This change was most apparent after 1 night of OK lens wear and, similar to changes in peripheral refraction, changes in corneal refractive power on subsequent days of OK treatment became less marked. Orthokeratology caused significant changes in both peripheral refraction and corneal topography. The greatest change in refraction and corneal refractive power across the horizontal corneal meridian occurred during the first night of OK lens wear. Subsequent changes in both peripheral refraction and corneal topography were less dramatic, in the same manner as reported changes in apical radius and central refraction after OK. This study confirms that with OK treatment, the peripheral retina experiences myopic defocus, which is conjectured to underlie the observed slowing of myopia progression. Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

A brief review of Boston type-1 and osteo-odonto keratoprostheses.

PubMed

Avadhanam, Venkata S; Liu, Christopher S C

2015-07-01

Globally there are ≈4.9 million bilaterally corneal blind and 23 million unilaterally corneal blind. Majority of this blindness exists in the developing countries, where resources for corneal banking and transplant surgery are less than adequate. Survival of corneal grafts gradually declines over the long term. Corneal transplantation has poor prognosis in vascularised corneal beds, ocular surface disease and viral keratitis. Keratoprosthesis (KPro) remains as a final option for end-stage ocular surface disease, multiple corneal transplant failures and high-risk corneal grafts. Boston type-1 KPro and osteo-odonto-keratoprosthesis are the two devices proven useful in recent years. Choice of a keratoprosthetic device is patient specific based on the underlying diagnosis, ocular morbidity and patient suitability. KPro surgery demands a high level of clinical and surgical expertise, lifelong commitment and extensive resources. Improvements in techniques and biomaterials may in the future provide retainable KPros that do not need regular follow-up of patients, have low complications but high retention rates and may be produced at a low cost on a mass scale to be available as 'off the shelf' devices. Because KPros have the potential to effectively address the burden of surgically treatable corneal blindness and may also eliminate the problems of corneal transplantation, more research is required to develop KPros as substitutes for corneal transplantation even in low-risk cases. In those countries where corneal blindness is a major liability, we need a two pronged approach: one to develop eye donation, eye banking and corneal transplantation and the second to establish centres for keratoprostheses, which are affordable and technically not challenging, in a population where default on follow-up visits are high. Until the latter is achieved, KPros should be viewed as a temporary means for visual restoration and be offered in national and supraregional specialised centres only. 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.

New refractive method for laser thermal keratoplasty with the Co:MgF2 laser.

PubMed

Horn, G; Spears, K G; Lopez, O; Lewicky, A; Yang, X Y; Riaz, M; Wang, R; Silva, D; Serafin, J

1990-09-01

We have observed corneal curvature changes from laser thermal keratoplasty with a Co:MgF2 laser. We studied corneal curvature changes in rabbits and have identified specific treatment patterns and laser parameters that can correct myopia and astigmatism. These corneal changes, some as large as 8 diopters, have been stable for at least one year, and slitlamp examination demonstrates clear central corneas with normal appearance.

Corneal Thickness Profile and Associations in Chinese Children Aged 7 to 15 Years Old.

PubMed

Ma, Yingyan; Zhu, Xiaofeng; He, Xiangui; Lu, Lina; Zhu, Jianfeng; Zou, Haidong

2016-01-01

Corneal thickness (CT) maps of the central (2-mm diameter), para-central (2 to 5-mm diameter), peripheral (5 to 6-mm diameter), and minimum (5-mm diameter) cornea were measured in normal Chinese school children aged 7 to 15 years old using Fourier-domain optical coherence tomography. Multiple regression analyses were performed to explore the effect of associated factors [age, gender, refraction, axial length and corneal curvature radius (CCR)] on CT and the relationship between central corneal thickness (CCT) and intraocular pressure (IOP). A total of 1228 eyes from 614 children were analyzed. The average CCT was 532.96 ± 28.33 μm for right eyes and 532.70 ±28.45 μm for left eyes. With a 10 μm increase in CCT, the IOP was elevated by 0.37 mm Hg, as measured by noncontact tonometry. The CT increased gradually from the center to the periphery. The superior and superior nasal regions had the thickest CTs, while the thinnest points were primarily located in the inferior temporal cornea. The CCT was associated with CCR (p = 0.008) but not with gender (p = 0.075), age (p = 0.286), axial length (p = 0.405), or refraction (p = 0.985). In the para-central region and the peripheral cornea, increased CT was associated with younger age, male gender, and a flatter cornea.

Preliminary results of a prospective study of inter- and intra-user variability of the Royal Veterinary College corneal clarity score (RVC-CCS) for use in veterinary practice.

PubMed

Sanchez, Rick F; Dawson, Charlotte; Matas Riera, Màrian; Escanilla, Natàlia

2016-07-01

To introduce a new corneal clarity score for use in small animals and describe its inter- and intra-user variability. Twelve dogs and two cats with corneal abnormalities and five dogs with healthy corneas. Four examiners scored every patient twice and never consecutively, focusing on the central cornea. The peripheral cornea was scored separately. The following scoring system was used to describe corneal clarity: G0: no fundus reflection is visible on retroillumination (RI) using a head-mounted indirect ophthalmoscope. G1: a fundus reflection is visible with RI. G2: a 0.1-mm diameter light beam is visible on the anterior surface of the iris and/or lens. G3: gross fundic features are visible when viewed with indirect ophthalmoscopy (IO) using a head-mounted indirect ophthalmoscope and a hand-held 30D lens, although fine details are not clear. G4: fine details of the fundic features are clearly visible with IO. The minimum grades given were analyzed for inter- and intra-user variability with kappa analysis. Intra- and interuser variability of the central corneal clarity ranged from 0.78 to 0.96, showing substantial to almost perfect reproducibility, and from 0.66 to 0.91, showing substantial to almost perfect reliability, respectively. Intra- and interuser variability of the peripheral cornea ranged from 0.83 to 0.95, showing almost perfect agreement, and from 0.53 to 0.91, showing moderate to almost perfect agreement. The RVC-CCS is well suited to assess and monitor central corneal clarity in small animals and to compare outcomes between studies and different surgeons. © 2015 American College of Veterinary Ophthalmologists.

Examination of tear film smoothness on corneae after refractive surgeries using a noninvasive interferometric method

NASA Astrophysics Data System (ADS)

Szczesna, Dorota H.; Kulas, Zbigniew; Kasprzak, Henryk T.; Stenevi, Ulf

2009-11-01

A lateral shearing interferometer was used to examine the smoothness of the tear film. The information about the distribution and stability of the precorneal tear film is carried out by the wavefront reflected from the surface of tears and coded in interference fringes. Smooth and regular fringes indicate a smooth tear film surface. On corneae after laser in situ keratomileusis (LASIK) or radial keratotomy (RK) surgery, the interference fringes are seldom regular. The fringes are bent on bright lines, which are interpreted as tear film breakups. The high-intensity pattern seems to appear in similar location on the corneal surface after refractive surgery. Our purpose was to extract information about the pattern existing under the interference fringes and calculate its shape reproducibility over time and following eye blinks. A low-pass filter was applied and correlation coefficient was calculated to compare a selected fragment of the template image to each of the following frames in the recorded sequence. High values of the correlation coefficient suggest that irregularities of the corneal epithelium might influence tear film instability and that tear film breakup may be associated with local irregularities of the corneal topography created after the LASIK and RK surgeries.

Scleral topography analysed by optical coherence tomography.

PubMed

Bandlitz, Stefan; Bäumer, Joachim; Conrad, Uwe; Wolffsohn, James

2017-08-01

A detailed evaluation of the corneo-scleral-profile (CSP) is of particular relevance in soft and scleral lenses fitting. The aim of this study was to use optical coherence tomography (OCT) to analyse the profile of the limbal sclera and to evaluate the relationship between central corneal radii, corneal eccentricity and scleral radii. Using OCT (Optos OCT/SLO; Dunfermline, Scotland, UK) the limbal scleral radii (SR) of 30 subjects (11M, 19F; mean age 23.8±2.0SD years) were measured in eight meridians 45° apart. Central corneal radii (CR) and corneal eccentricity (CE) were evaluated using the Oculus Keratograph 4 (Oculus, Wetzlar, Germany). Differences between SR in the meridians and the associations between SR and corneal topography were assessed. Median SR measured along 45° (58.0; interquartile range, 46.8-84.8mm) was significantly (p<0.001) flatter than along 0° (30.7; 24.5-44.3mm), 135° (28.4; 24.9-30.9mm), 180° (23.40; 21.3-25.4mm), 225° (25.8; 22.4-32.4mm), 270° (28.8; 25.3-33.1mm), 315° (30.0; 25.0-36.9mm), and 90° (37.1; 29.1-43.4mm). In addition, the nasal SR along 0° were significant flatter than the temporal SR along 180° (p<0.001). Central corneal radius in the flat meridian (7.83±0.26mm) and in the steep meridian (7.65±0.26mm) did not correlate with SR (p=0.186 to 0.998). There was no statistically significant correlation between corneal eccentricity and scleral radii in each meridian (p=0.422). With the OCT device used in this study it was possible to measure scleral radii in eight different meridians. Scleral radii are independent of corneal topography and may provide additional data useful in fitting soft and scleral contact lenses. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Eye care for patients receiving neuromuscular blocking agents or propofol during mechanical ventilation.

PubMed

Lenart, S B; Garrity, J A

2000-05-01

The presence of a corneal reflex and the ability to maintain eye closure are instrumental in protecting the cornea. Use of neuromuscular blocking agents or propofol can result in impaired eyelid closure and loss of corneal reflex, leading to corneal exposure. The cornea is then at risk for drying, infection, and scarring, which may lead to permanent visual loss. To determine whether applying artificial tear ointment to the eyes of paralyzed or heavily sedated patients receiving mechanical ventilation decreases the prevalence of exposure keratitis more than does passive closure of the eyelid. A prospective, randomized control trial was done. The sample was 50 patients in the intensive care unit receiving either neuromuscular blocking agents or propofol during mechanical ventilation. In each patient, artificial tear ointment was applied to one eye; passive closure of the eyelid was used for the other eye (control eye). Nine patients had evidence of exposure keratitis in the untreated eye, and 2 had corneal abrasions in both the treated and the control eyes. The remaining 39 patients did not have corneal abrasions in either eye. Use of the artificial tear ointment was more effective in preventing corneal exposure than was passive eyelid closure (P = .004). Eye care with a lubricating ointment on a regular, set schedule can effectively reduce the prevalence of corneal abrasions in patients who are either paralyzed or heavily sedated and thus can help prevent serious complications such as corneal ulceration, infection, and visual loss.

Corneal thickness differences between sexes after oxybuprocaine eye drops.

PubMed

Fernandez-Garcia, Pablo; Cerviño, Alejandro; Quiles-Guiñau, Laura; Albarran-Diego, Cesar; Garcia-Lazaro, Santiago; Sanchis-Gimeno, Juan A

2015-01-01

We aimed to analyze the corneal thickness (CT) values of female and male subjects before and after instillation of oxybuprocaine 0.4% anesthetic eye drops. The CT of 30 female subjects and 28 male subjects was measured using scanning-slit corneal topography (Orbscan Topography System II, Orbscan, Inc, Salt Lake City, UT). Measurements were carried out before and 3 minutes after the instillation of oxybuprocaine 0.4% eye drops. The difference between the baseline values and those obtained after anesthesia ranged as follows: male subjects: central, -26 to +24 μm; superior, -24 to +23 μm; inferior, -19 to +20 μm; nasal, -25 to +30 μm; and temporal, -21 to +20 μm; female subjects: central, -16 to +24 μm; superior, -19 to +32 μm; inferior, -14 to +34 μm; nasal, -19 to +33 μm; and temporal, -36 to +16 μm. No significant differences were found in any corneal location in male subjects. The differences were significant at inferior (p = 0.001) and nasal (p = 0.011) corneal sites in female subjects. Oxybuprocaine anesthetic eye drops induce significant CT increases in female subjects but not in male subjects.

Changes in biomechanical properties of the cornea and intraocular pressure after myopic laser in situ keratomileusis using a femtosecond laser for flap creation determined using ocular response analyzer and Goldmann applanation tonometry.

PubMed

Shin, Jonghoon; Kim, Tae Won; Park, Soo Jeong; Yoon, Min; Lee, Ji Woong

2015-03-01

To compare intraocular pressure (IOP) measurements before and after laser in situ keratomileusis (LASIK) using a femtosecond laser for flap creation, and to identify factors that may influence the preoperative and postoperative IOP, and the change in IOP after LASIK. Forty eyes from 20 patients who underwent treatment for myopia using a femtosecond laser for flap creation were enrolled in this study. The IOP and corneal biomechanical markers were prospectively measured preoperatively and 1 month after LASIK with Goldmann applanation tonometry (GAT) and the ocular response analyzer (ORA). Manifest refraction spherical equivalent, central corneal thickness, ablation depth, and mean corneal curvature (K reading) were also recorded. After LASIK, there was a significant reduction in the IOP measurement with respect to the corneal-compensated intraocular pressure (IOPcc) (Δ=-0.67±2.07 mm Hg), Goldmann-correlated pressure (IOPg) (Δ=-3.92±2.19 mm Hg), and GAT (Δ=-2.6±2.51). Multiple regression analysis revealed that the corneal hysteresis (CH) and corneal resistance factor (CRF) are statistically significant predictors of IOPcc, IOPg, and GAT (P<0.000). In this analysis, the preoperative manifest refraction spherical equivalent, CH, and CRF were significant predictors of ΔIOPcc (adjusted R²=0.401) and ΔIOPg (adjusted R²=0.386). The preoperative SE and central corneal thickness significantly predicted ΔGAT (adjusted R²=0.464). ORA provides a more complete measurement of IOP after LASIK with a femtosecond laser than GAT because ORA provides greater knowledge of the corneal biomechanics in terms of CH and CRF.

Coupling of HRT II and AS-OCT to evaluate corneal endothelial cell loss and in vivo visualization of the Ahmed glaucoma valve implant.

PubMed

Mendrinos, E; Dosso, A; Sommerhalder, J; Shaarawy, T

2009-09-01

To report corneal endothelial cell loss and in vivo visualization of the Ahmed glaucoma valve implant in eyes with refractory glaucoma. Ten eyes underwent Ahmed valve implant surgery and were followed-up for 12 months. Data collected included intraocular pressure (IOP), number of antiglaucoma medications and surgery-related complications. At 6 and 12 months postoperatively, the intracameral length of the drainage tube (ICL) and the distance between the tube and the cornea (T-C distance), and the iris (T-I distance) were assessed using anterior segment optical coherence tomography (AS-OCT). Heidelberg cornea tomograph II (HRT II) was used to measure the corneal endothelial cell density. Mean (+/-SEM) preoperative IOP was 29.5+/-4 mmHg. Mean postoperative IOP was 11.6+/-2 at 12 months (P<0.01). Over a 6-month period, mean corneal endothelial loss was 7.9%+/-2.5 in the central and 7.5%+/-2.4 in the peripheral cornea (P<0.01). There was no correlation between central or peripheral corneal endothelial cell loss and the T-C, T-I distance or the ICL of the tube. Corneal endothelial cell loss occurs following Ahmed valve implant surgery, this appears to be multifactorial. AS-OCT and HRT II are promising methods for the follow-up of patients with a glaucoma drainage device.

Interaction of corneal nociceptive stimulation and lacrimal secretion.

PubMed

Situ, Ping; Simpson, Trefford L

2010-11-01

To investigate the interaction between corneal stimuli at different positions and tear secretion and to establish relationships between nociceptive stimuli detection thresholds and stimulated tearing. Using a computerized Belmonte-esthesiometer, mechanical and chemical stimuli, from 0% to 200% of the threshold in 50% steps, were delivered (in random order) to the central and peripheral (approximately 2-mm inside the limbus) cornea during four separate sessions to 15 subjects. Immediately after each stimulus, tear meniscus height (TMH) was measured using optical coherence tomography to quantify the amount of lacrimal secretion, and subjects reported whether they felt tears starting to accumulate in their eyes. Thresholds (50% detection) for detection of tearing were estimated. TMH increased with increasing stimulus intensity (P < 0.05), and the overall increase was higher with central stimulation than with peripheral stimulation (P < 0.05). The changes in TMH with threshold-scaled stimulus intensity depended on test location (P < 0.05) and stimulus modality (P < 0.05). The maximum intensity of mechanical stimulation of the central cornea induced the greatest TMH (all P < 0.05). For chemical stimulation, the stimulus intensity required to induce detectable tearing was higher than that required to detect a stimulus and higher in the periphery than at the center (all P < 0.05). Noxious mechanical and chemical stimuli evoked measurable tear secretion, with central corneal mechanical stimulation evoking the strongest lacrimation reflex. Central mechanical corneal stimulation is the most effective stimulus-position pairing and appears to be the major sensory driving force for reflex tear secretion by the lacrimal functional unit.

Assessing microstructures of the cornea with Gabor-domain optical coherence microscopy: pathway for corneal physiology and diseases.

PubMed

Tankam, Patrice; He, Zhiguo; Chu, Ying-Ju; Won, Jungeun; Canavesi, Cristina; Lepine, Thierry; Hindman, Holly B; Topham, David J; Gain, Philippe; Thuret, Gilles; Rolland, Jannick P

2015-03-15

Gabor-domain optical coherence microscopy (GD-OCM) was applied ex vivo in the investigation of corneal cells and their surrounding microstructures with particular attention to the corneal endothelium. Experiments using fresh pig eyeballs, excised human corneal buttons from patients with Fuchs' endothelial dystrophy (FED), and healthy donor corneas were conducted. Results show in a large field of view (1  mm×1  mm) high definition images of the different cell types and their surrounding microstructures through the full corneal thickness at both the central and peripheral locations of porcine corneas. Particularly, an image of the endothelial cells lining the bottom of the cornea is highlighted. As compared to healthy human corneas, the corneas of individuals with FED show characteristic microstructural alterations of the Descemet's membrane and increased size and number of keratocytes. The GD-OCM-based imaging system developed may constitute a novel tool for corneal imaging and disease diagnosis. Also, importantly, it may provide insights into the mechanism of corneal physiology and pathology, particularly in diseases of the corneal endothelium.

Cornea and anterior eye assessment with placido-disc keratoscopy, slit scanning evaluation topography and scheimpflug imaging tomography

PubMed Central

Martin, Raul

2018-01-01

Current corneal assessment technologies make the process of corneal evaluation extremely fast and simple and several devices and technologies allow to explore and to manage patients. The purpose of this special issue is to present and also to update in the evaluation of cornea and ocular surface and this second part, reviews a description of the corneal topography and tomography techniques, providing updated information of the clinical recommendations of these techniques in eye care practice. Placido-based topographers started an exciting anterior corneal surface analysis that allows the development of current corneal tomographers that provide a full three-dimensional reconstruction of the cornea including elevation, curvature, and pachymetry data of anterior and posterior corneal surfaces. Although, there is not an accepted reference standard technology for corneal topography description and it is not possible to determine which device produces the most accurate topographic measurements, placido-based topographers are a valuable technology to be used in primary eye care and corneal tomograhers expanding the possibilities to explore cornea and anterior eye facilitating diagnosis and follow-up in several situations, raising patient follow-up, and improving the knowledge regarding to the corneal anatomy. Main disadvantages of placido-based topographers include the absence of information about the posterior corneal surface and limited corneal surface coverage without data from the para-central and/or peripheral corneal surface. However, corneal tomographers show repeatable anterior and posterior corneal surfaces measurements, providing full corneal thickness data improving cornea, and anterior surface assessment. However, differences between devices suggest that they are not interchangeable in clinical practice. PMID:29480244

Cornea and anterior eye assessment with placido-disc keratoscopy, slit scanning evaluation topography and scheimpflug imaging tomography.

PubMed

Martin, Raul

2018-03-01

Current corneal assessment technologies make the process of corneal evaluation extremely fast and simple and several devices and technologies allow to explore and to manage patients. The purpose of this special issue is to present and also to update in the evaluation of cornea and ocular surface and this second part, reviews a description of the corneal topography and tomography techniques, providing updated information of the clinical recommendations of these techniques in eye care practice. Placido-based topographers started an exciting anterior corneal surface analysis that allows the development of current corneal tomographers that provide a full three-dimensional reconstruction of the cornea including elevation, curvature, and pachymetry data of anterior and posterior corneal surfaces. Although, there is not an accepted reference standard technology for corneal topography description and it is not possible to determine which device produces the most accurate topographic measurements, placido-based topographers are a valuable technology to be used in primary eye care and corneal tomograhers expanding the possibilities to explore cornea and anterior eye facilitating diagnosis and follow-up in several situations, raising patient follow-up, and improving the knowledge regarding to the corneal anatomy. Main disadvantages of placido-based topographers include the absence of information about the posterior corneal surface and limited corneal surface coverage without data from the para-central and/or peripheral corneal surface. However, corneal tomographers show repeatable anterior and posterior corneal surfaces measurements, providing full corneal thickness data improving cornea, and anterior surface assessment. However, differences between devices suggest that they are not interchangeable in clinical practice.

The characteristics of premature infants with transient corneal haze.

PubMed

Lai, Yu-Hung; Chen, Hsiu-Lin; Yang, San-Nan; Chang, Shun-Jen; Chuang, Lea-Yea; Wu, Wen-Chuan

2018-01-01

The etiology of transient corneal haze in premature infants is not known and how it relates to clinical outcomes in premature infants is not clear. To study associated factors of transient corneal haze in premature infants. We performed a retrospective study of 261 premature infants from retinopathy of prematurity (ROP) screening in the neonatal intensive care unit at a tertiary referral hospital. Characteristics of premature infants with and without corneal haze were analyzed by correlation tests, Chi-square tests, and logistic regressions were used for statistical analyses. Associations between corneal haze and birth weight (BW), gestational age at birth (GA), central corneal thickness, intraocular pressure, and other systemic and ophthalmic data were evaluated. The incidence of corneal haze was 13.4%. Lower BW, lower GA, packed red blood cells (RBC) transfusion, more days on oxygen, older maternal age, bronchopulmonary disease, and stage 3 ROP are associated with corneal haze. The severity of corneal haze decreased with infants' postmenstrual age. Multivariate logistic regression analyses revealed that BW and maternal age are the most important predictors of corneal haze. Low BW and older maternal age are the most important predictors of corneal haze in premature infants. Premature infants with corneal haze could carry more systemic and ocular morbidities. Hence they may require more clinical attention. Corneal haze is unlikely to hinder the treatment of ROP. However, it is possible that corneal haze could hinder the examination of ROP in some infants. If corneal haze does interfere with ROP screening, a closer, more conservative follow-up schedule with a senior ophthalmologist experienced in managing ROP is recommended.

Corneal topographic changes following strabismus surgery in Grave's disease.

PubMed

Kwitko, S; Feldon, S; McDonnell, P J

1992-01-01

A computerized topographic analysis system was used to evaluate corneal changes after strabismus surgery in eight eyes of five patients with Graves' disease. All patients underwent inferior rectus muscle recession; three eyes also had medial rectus recession. Corneal topographic analysis revealed that, postoperatively, corneas steepened inferiorly and inferotemporally at 1.5 mm from corneal apex (p less than 0.05). The opposite effect was observed in the superior quadrant (average flattening of 1.20 +/- 0.32 D at 1.5 mm from corneal apex, and 1.08 +/- 0.39 D at 3.0 mm from corneal apex; p less than 0.05). Superotemporally, the cornea flattened by an average of 0.65 +/- 0.26 D at 3.0 mm from corneal apex, and superonasally 0.72 +/- 0.19 D at 3.0 mm from corneal apex (p less than 0.05). Central, nasal, and temporal cornea did not show statistically significant changes. Spherical equivalent did not change significantly after surgery. The amount of restriction and upgaze measured preoperatively was correlated weakly with inferior corneal steepening (r2 = 0.44; p = 0.046). These results are indicative that corneal topography may be influenced by strabismus surgery for Graves' disease through alteration of extraocular muscle tension or intraocular pressure.

Corneal thickness values before and after oxybuprocaine 0.4% eye drops.

PubMed

Asensio, Isabel; Rahhal, Saleh M; Alonso, Luis; Palanca-Sanfrancisco, José M; Sanchis-Gimeno, Juan A

2003-08-01

To determine changes in corneal thickness after topical anesthesia. Corneal thickness was measured before and 3 minutes after administration of two drops of oxybuprocaine 0.4% to 26 patients (26 eyes). We analyzed the corneal thickness of a control group, which was made up of 26 patients (26 eyes) before and 3 minutes after administration of two drops of saline solution. Corneal thickness was measured with the Orbscan Topography System II (Bausch Lomb Surg., Barcelona). Variations higher than +/- 10 microm were found following the instillation of 2 oxybuprocaine eye drops in eight eyes (30.76%) at the inferonasal cornea, in six eyes (23.08%) at the superotemporal, temporal and inferotemporal cornea, in five eyes (19.23%) at the nasal cornea, in three eyes (11.53%) at the central cornea, and in two eyes (7.69%) at the superonasal cornea. Nevertheless, no significant differences in the mean corneal thickness at each corneal location between the first and the second corneal thickness measurements were found in anesthetized eyes. Some individuals can present important increases and decreases in corneal thickness values after anesthetic eye drops. This effect of anesthetic eye drops must be considered by refractive surgeons when carrying out preoperative laser in situ keratomileusis corneal thickness measurements.

The effect of mydriasis from phenylephrine on corneal shape.

PubMed

Huang, Ronnie Y C; Lam, Andrew K C

2007-01-01

A previous study reported that pharmacologically-dilated pupils changed the corneal shape. Researchers used mydriatic agents with significant cycloplegic effect. The current study investigates the effect of mydriasis on corneal shape using phenylephrine alone, where phenylephrine has minimal effect on the accommodative system and whether corneal topography can be done after pupil dilation. Forty-four young healthy subjects with one eye randomly selected for mydriasis were used in this study. Twenty-two received one drop of 2.5% phenylephrine (group 1); the other 22 subjects had one drop of 0.4% benoxinate instilled prior to the application of 2.5% phenylephrine (group 2). They were matched for age and refractive error. Anterior chamber depth, pupil size and corneal parameters were compared before and after mydriasis. The corneal parameters included best-fit sphere (BFS), surface asymmetry index (SAI), surface regularity index (SRI) and the axial and tangential powers in the form of flattest and steepest powers, and in the form of M, J(0), and J(45) vector presentation. Group 1 and group 2 subjects had similar pre-mydriatic baseline ocular parameters. The mean (+/- SD) pupil dilation was 1.24 +/- 0.59 mm for group 1 and 1.80 +/- 0.95 mm for group 2. The dilation was significantly larger in group 2 (unpaired t-tests: t = 2.36, p = 0.02). There were no significant changes in corneal parameters from mydriasis in either group. Previous investigations used mydriatic agents, which affected not only the pupil size but also accommodation. The current study found that mydriasis from phenylephrine, with minimal effect on accommodation, did not result in significant corneal alteration, and corneal topography can be measured after pupil dilation with phenylephrine.

Correlation between central corneal thickness and visual field defects, cup to disc ratio and retinal nerve fiber layer thickness in primary open angle glaucoma patients.

PubMed

Sarfraz, Muhammad Haroon; Mehboob, Mohammad Asim; Haq, Rana Intisar Ul

2017-01-01

To evaluate the correlation between Central Corneal Thickness (CCT) and Visual Field (VF) defect parameters like Mean Deviation (MD) and Pattern Standard Deviation (PSD), Cup-to-Disc Ratio (CDR) and Retinal Nerve Fibre Layer Thickness (RNFL-T) in Primary Open-Angle Glaucoma (POAG) patients. This cross sectional study was conducted at Armed Forces Institute of Ophthalmology (AFIO), Rawalpindi from September 2015 to September 2016. Sixty eyes of 30 patients with diagnosed POAG were analysed. Correlation of CCT with other variables was studied. Mean age of study population was 43.13±7.54 years. Out of 30 patients, 19 (63.33%) were males and 11 (36.67%) were females. Mean CCT, MD, PSD, CDR and RNFL-T of study population was 528.57±25.47µm, -9.11±3.07, 6.93±2.73, 0.63±0.13 and 77.79±10.44µm respectively. There was significant correlation of CCT with MD, PSD and CDR (r=-0.52, p<0.001; r=-0.59, p<0.001;r=-0.41, p=0.001 respectively). The correlation of CCT with RNFL-T was not statistically significant (r=-0.14, p=0.284). Central corneal thickness had significant correlation with visual field parameters like mean deviation and pattern standard deviation, as well as with cup-to-disc ratio. However, central corneal thickness had no significant relationship with retinal nerve fibre layer thickness.

Patterned corneal collagen crosslinking for astigmatism: Computational modeling study

PubMed Central

Seven, Ibrahim; Roy, Abhijit Sinha; Dupps, William J.

2014-01-01

PURPOSE To test the hypothesis that spatially selective corneal stromal stiffening can alter corneal astigmatism and assess the effects of treatment orientation, pattern, and material model complexity in computational models using patient-specific geometries. SETTING Cornea and Refractive Surgery Service, Academic Eye Institute, Cleveland, Ohio, USA. DESIGN Computational modeling study. METHODS Three-dimensional corneal geometries from 10 patients with corneal astigmatism were exported from a clinical tomography system (Pentacam). Corneoscleral finite element models of each eye were generated. Four candidate treatment patterns were simulated, and the effects of treatment orientation and magnitude of stiffening on anterior curvature and aberrations were studied. The effect of material model complexity on simulated outcomes was also assessed. RESULTS Pretreatment anterior corneal astigmatism ranged from 1.22 to 3.92 diopters (D) in a series that included regular and irregular astigmatic patterns. All simulated treatment patterns oriented on the flat axis resulted in mean reductions in corneal astigmatism and depended on the pattern geometry. The linear bow-tie pattern produced a greater mean reduction in astigmatism (1.08 D ± 0.13 [SD]; range 0.74 to 1.23 D) than other patterns tested under an assumed 2-times increase in corneal stiffness, and it had a nonlinear relationship to the degree of stiffening. The mean astigmatic effect did not change significantly with a fiber- or depth-dependent model, but it did affect the coupling ratio. CONCLUSIONS In silico simulations based on patient-specific geometries suggest that clinically significant reductions in astigmatism are possible with patterned collagen crosslinking. Effect magnitude was dependent on patient-specific geometry, effective stiffening pattern, and treatment orientation. PMID:24767795

Inflammation and the nervous system: the connection in the cornea in patients with infectious keratitis.

PubMed

Cruzat, Andrea; Witkin, Deborah; Baniasadi, Neda; Zheng, Lixin; Ciolino, Joseph B; Jurkunas, Ula V; Chodosh, James; Pavan-Langston, Deborah; Dana, Reza; Hamrah, Pedram

2011-07-11

To study the density and morphologic characteristics of epithelial dendritic cells, as correlated to subbasal corneal nerve alterations in acute infectious keratitis (IK) by in vivo confocal microscopy (IVCM). IVCM of the central cornea was performed prospectively in 53 eyes with acute bacterial (n = 23), fungal (n = 13), and Acanthamoeba (n = 17) keratitis, and in 20 normal eyes, by using laser in vivo confocal microscopy. Density and morphology of dendritic-shaped cells (DCs) of the central cornea, corneal nerve density, nerve numbers, branching, and tortuosity were assessed and correlated. It should be noted that due to the "in vivo" nature of the study, the exact identity of these DCs cannot be specified, as they could be monocytes or tissue macrophages, but most likely dendritic cells. IVCM revealed the presence of central corneal DCs in all patients and controls. The mean DC density was significantly higher in patients with bacterial (441.1 ± 320.5 cells/mm(2); P < 0.0001), fungal (608.9 ± 812.5 cells/mm(2); P < 0.0001), and Acanthamoeba keratitis (1000.2 ± 1090.3 cells/mm(2); P < 0.0001) compared with controls (49.3 ± 39.6 cells/mm(2)). DCs had an increased size and dendrites in patients with IK. Corneal nerves were significantly reduced in eyes with IK compared with controls across all subgroups, including nerve density (674.2 ± 976.1 vs. 3913.9 ± 507.4 μm/frame), total nerve numbers (2.7 ± 3.9 vs. 20.2 ± 3.3), main trunks (1.5 ± 2.2 vs. 6.9 ± 1.1), and branching (1.2 ± 2.0 vs. 13.5 ± 3.1; P < 0.0001). A strong association between the diminishment of corneal nerves and the increase of DC density was observed (r = -0.44; P < 0.0005). IVCM reveals an increased density and morphologic changes of central epithelial DCs in infectious keratitis. There is a strong and significant correlation between the increase in DC numbers and the decreased subbasal corneal nerves, suggesting a potential interaction between the immune and nervous system in the cornea.

In vivo morphology of the limbal palisades of vogt correlates with progressive stem cell deficiency in aniridia-related keratopathy.

PubMed

Lagali, Neil; Edén, Ulla; Utheim, Tor Paaske; Chen, Xiangjun; Riise, Ruth; Dellby, Anette; Fagerholm, Per

2013-08-07

To investigate morphologic alterations in the limbal palisades of Vogt in a progressive form of limbal stem cell deficiency. Twenty Norwegian subjects (40 eyes) with congenital aniridia and 9 healthy family members (18 eyes) without aniridia were examined. Clinical grade of aniridia-related keratopathy (ARK) was assessed by slit-lamp biomicroscopy, and tear production and quality, corneal thickness, and sensitivity were additionally measured. The superior and inferior limbal palisades of Vogt and central cornea were examined by laser scanning in vivo confocal microscopy (IVCM). In an aniridia patient with grade 0 ARK, a transparent cornea and normal limbal palisade morphology were found. In grade 1 ARK, 5 of 12 eyes had degraded palisade structures. In the remaining grade 1 eyes and in all 20 eyes with stage 2, 3, and 4 ARK, palisade structures were absent by IVCM. Increasing ARK grade significantly correlated with reduced visual acuity and corneal sensitivity, increased corneal thickness, degree of degradation of superior and inferior palisade structures, reduced peripheral nerves, increased inflammatory cell invasion, and reduced density of basal epithelial cells and central subbasal nerves. Moreover, limbal basal epithelial cell density and central corneal subbasal nerve density were both significantly reduced in aniridia compared to healthy corneas (P = 0.002 and 0.003, respectively). Progression of limbal stem cell deficiency in aniridia correlates with degradation of palisade structures, gradual transformation of epithelial phenotype, onset of inflammation, and a corneal nerve deficit. IVCM can be useful in monitoring early- to late-stage degenerative changes in stem cell-deficient patients.

The central corneal light reflex ratio from photographs derived from a digital camera in young adults.

PubMed

Duangsang, Suampa; Tengtrisorn, Supaporn

2012-05-01

To determine the normal range of Central Corneal Light Reflex Ratio (CCLRR) from photographs of young adults. A digital camera equipped with a telephoto lens with a flash attachment placed directly above the lens was used to obtain corneal light reflex photographs of 104 subjects, first with the subject fixating on the lens of the camera at a distance of 43 centimeters, and then while looking past the camera to a wall at a distance of 5.4 meters. Digital images were displayed using Adobe Photoshop at a magnification of l200%. The CCLRR was the ratio of the sum of distances between the inner margin of cornea and the central corneal light reflex of each eye to the sum of horizontal corneal diameter of each eye. Measurements were made by three technicians on all subjects, and repeated on a 16% (n=17) subsample. Mean ratios (standard deviation-SD) from near/distance measurements were 0.468 (0.012)/0.452 (0.019). Limits of the normal range, with 95% certainty, were 0.448 and 0.488 for near measurements and 0.419 and 0.484 for distance measurements. Lower and upper indeterminate zones were 0.440-0.447 and 0.489-0.497 for near measurements and 0.406-0.418 and 0.485-0.497 for distance measurements. More extreme values can be considered as abnormal. The reproducibility and repeatability of the test was good. This method is easy to perform and has potential for use in strabismus screening by paramedical personnel.

New therapeutic modality for corneal endothelial disease using Rho-associated kinase inhibitor eye drops.

PubMed

Koizumi, Noriko; Okumura, Naoki; Ueno, Morio; Kinoshita, Shigeru

2014-11-01

Corneal endothelial dysfunction accompanied by visual disturbance is a primary indication for corneal endothelial transplantation. However, despite the value and potential of endothelial graft surgery, a strictly pharmacological approach for treating corneal endothelial dysfunction remains an attractive proposition. Previously, we reported that the selective Rho-associated kinase (ROCK) inhibitor Y-27632 promotes cell adhesion and proliferation, and inhibits the apoptosis of primate corneal endothelial cells in culture. These findings have led us to develop a novel medical treatment for the early phase of corneal endothelial disease using ROCK inhibitor eye drops. In rabbit and monkey models of partial endothelial dysfunction, we showed that corneal endothelial wound healing was accelerated via the topical application of ROCK inhibitor to the ocular surface, resulting in the regeneration of a corneal endothelial monolayer with a high endothelial cell density. Based on these animal studies, we are now attempting to advance the clinical application of ROCK inhibitor eye drops for patients with corneal endothelial dysfunction. A pilot clinical study was performed at the Kyoto Prefectural University of Medicine, and the effects of Y-27632 eye drops after transcorneal freezing were evaluated in 8 patients with corneal endothelial dysfunction. We observed a positive effect of ROCK inhibitor eye drops in treating patients with central edema caused by Fuchs corneal endothelial dystrophy. We believe that our new findings will contribute to the establishment of a new approach for the treatment of corneal endothelial dysfunction.

A new fish scale-derived scaffold for corneal regeneration.

PubMed

Lin, Chien Chen; Ritch, Robert; Lin, Shang Ming; Ni, Mei-Hui; Chang, Yu-Chung; Lu, Yi Lung; Lai, Hong Ji; Lin, Feng-Huei

2010-02-26

The purpose of this study is to develop a novel scaffold, derived from fish scales, as an alternative functional material with sufficient mechanical strength for corneal regenerative applications. Fish scales, which are usually considered as marine wastes, were acellularized, decalcified and fabricated into collagen scaffolds. The microstructure of the acellularized scaffold was imaged by scanning electron microscopy (SEM). The acellularization and decalcification treatments did not affect the naturally 3-dimentional, highly centrally-oriented micropatterned structure of the material. To assess the cytocompatibility of the scaffold with corneal cells, rabbit corneal cells were cultured on the scaffold and examined under SEM and confocal microscopy at different time periods. Rapid cell proliferation and migration on the scaffold were observed under SEM and confocal microscopy. The highly centrally-oriented micropatterned structure of the scaffold was beneficial for efficient nutrient and oxygen supply to the cells cultured in the three-dimensional matrices, and therefore it is useful for high-density cell seeding and spreading. Collectively, we demonstrate the superior cellular conductivity of the newly developed material. We provide evidences for the feasibility of the scaffold as a template for corneal cells growth and migration, and thus the fish scale-derived scaffold can be developed as a promising material for tissue-engineering of cornea.

Comparison of torsional and microburst longitudinal phacoemulsification: a prospective, randomized, masked clinical trial.

PubMed

Vasavada, Abhay R; Raj, Shetal M; Patel, Udayan; Vasavada, Vaishali; Vasavada, Viraj

2010-01-01

To compare intraoperative performance and postoperative outcome of three phacoemulsification technologies in patients undergoing microcoaxial phacoemulsification through 2.2-mm corneal incisions. The prospective, randomized, single-masked study included 360 eyes randomly assigned to torsional (Infiniti Vision System; Alcon Laboratories, Fort Worth, TX), microburst with longitudinal (Infiniti), or microburst with longitudinal (Legacy Everest, Alcon Laboratories) ultrasound. Assessments included surgical clock time, fluid volume, and intraoperative complications, central corneal thickness on day 1 and months 1 and 3 postoperatively, and endothelial cell density at 3 months postoperatively. Comparisons among groups were conducted. Torsional ultrasound required significantly less surgical clock time and fluid volume than the other groups. There were no intraoperative complications. Change in central corneal thickness and endothelial cell loss was significantly lower in the torsional ultrasound group at all postoperative visits (P < .001, Kruskal-Wallis test) compared to microburst longitudinal ultrasound modalities. Torsional ultrasound demonstrated quantitatively superior intraoperative performance and showed less increase in corneal thickness and less endothelial cell loss compared to microburst longitudinal ultrasound. Copyright 2010, SLACK Incorporated.

Modeling the influence of LASIK surgery on optical properties of the human eye

NASA Astrophysics Data System (ADS)

Szul-Pietrzak, Elżbieta; Hachoł, Andrzej; Cieślak, Krzysztof; Drożdż, Ryszard; Podbielska, Halina

2011-11-01

The aim was to model the influence of LASIK surgery on the optical parameters of the human eye and to ascertain which factors besides the central corneal radius of curvature and central thickness play the major role in postsurgical refractive change. Ten patients were included in the study. Pre- and postsurgical measurements included standard refraction, anterior corneal curvature and pachymetry. The optical model used in the analysis was based on the Le Grand and El Hage schematic eye, modified by the measured individual parameters of corneal geometry. A substantial difference between eye refractive error measured after LASIK and estimated from the eye model was observed. In three patients, full correction of the refractive error was achieved. However, analysis of the visual quality in terms of spot diagrams and optical transfer functions of the eye optical system revealed some differences in these measurements. This suggests that other factors besides corneal geometry may play a major role in postsurgical refraction. In this paper we investigated whether the biomechanical properties of the eyeball and changes in intraocular pressure could account for the observed discrepancies.

Effects of corneal thickness on the intraocular penetration of travoprost 0.004%

PubMed Central

Martinez-de-la-Casa, J M; Rayward, O; Saenz-Frances, F; Santos-Bueso, E; Mendez-Hernandez, C; Herrero-Vanrell, R; Garcia-Feijoo, J; Garcia-Sanchez, J

2012-01-01

Purpose To determine whether the intraocular penetration of travoprost 0.004% is affected by central corneal thickness. Methods Sixty-four patients who were scheduled for cataract surgery without any other ophthalmologic pathology of significance were enroled in this study. At 120 min before surgery, one drop of travoprost 0.004% was instilled in the eye to be operated on. At the start of surgery, a sample of aqueous humour was extracted to subsequently determine its AL-5848 concentration. These concentrations were compared among three groups of patients established according to central corneal thickness measurements obtained by ultrasound pachymetry. Results Mean AL-5848 concentrations were 3.27±2.03 ng/ml in Group I (CCT<511 microns), 3.27±2.44 ng/ml in Group II (CCT≥511 and ≤574 microns), and 2.73±2.15 ng/ml in Group III (CCT>574 microns), indicating no significant differences among the groups. Conclusions We were unable to demonstrate the greater or lesser penetration of travoprost depending on corneal thickness, which could explain differences in patient responses to this drug. PMID:22562189

Photorefractive keratectomy in the cat eye: biological and optical outcomes.

PubMed

Nagy, Lana J; MacRae, Scott; Yoon, Geunyoung; Wyble, Matthew; Wang, Jianhua; Cox, Ian; Huxlin, Krystel R

2007-06-01

To quantify optical and biomechanical properties of the feline cornea before and after photorefractive keratectomy (PRK) and assess the relative contribution of different biological factors to refractive outcome. Department of Ophthalmology, University of Rochester, Rochester, New York, USA. Adult cats had 6.0 diopter (D) myopic or 4.0 D hyperopic PRK over 6.0 or 8.0 mm optical zones (OZ). Preoperative and postoperative wavefront aberrations were measured, as were intraocular pressure (IOP), corneal hysteresis, the corneal resistance factor, axial length, corneal thickness, and radii of curvature. Finally, postmortem immunohistochemistry for vimentin and alpha-smooth muscle actin was performed. Photorefractive keratectomy changed ocular defocus, increased higher-order aberrations, and induced myofibroblast differentiation in cats. However, the intended defocus corrections were only achieved with 8.0 mm OZs. Long-term flattening of the epithelial and stromal surfaces was noted after myopic, but not after hyperopic, PRK. The IOP was unaltered by PRK; however, corneal hysteresis and the corneal resistance factor decreased. Over the ensuing 6 months, ocular aberrations and the IOP remained stable, while central corneal thickness, corneal hysteresis, and the corneal resistance factor increased toward normal levels. Cat corneas exhibited optical, histological, and biomechanical reactions to PRK that resembled those previously described in humans, especially when the OZ size was normalized to the total corneal area. However, cats exhibited significant stromal regeneration, causing a return to preoperative corneal thickness, corneal hysteresis and the corneal resistance factor without significant regression of optical changes induced by the surgery. Thus, the principal effects of laser refractive surgery on ocular wavefront aberrations can be achieved despite clear interspecies differences in corneal biology.

Material Properties from Air Puff Corneal Deformation by Numerical Simulations on Model Corneas.

PubMed

Bekesi, Nandor; Dorronsoro, Carlos; de la Hoz, Andrés; Marcos, Susana

2016-01-01

To validate a new method for reconstructing corneal biomechanical properties from air puff corneal deformation images using hydrogel polymer model corneas and porcine corneas. Air puff deformation imaging was performed on model eyes with artificial corneas made out of three different hydrogel materials with three different thicknesses and on porcine eyes, at constant intraocular pressure of 15 mmHg. The cornea air puff deformation was modeled using finite elements, and hyperelastic material parameters were determined through inverse modeling, minimizing the difference between the simulated and the measured central deformation amplitude and central-peripheral deformation ratio parameters. Uniaxial tensile tests were performed on the model cornea materials as well as on corneal strips, and the results were compared to stress-strain simulations assuming the reconstructed material parameters. The measured and simulated spatial and temporal profiles of the air puff deformation tests were in good agreement (< 7% average discrepancy). The simulated stress-strain curves of the studied hydrogel corneal materials fitted well the experimental stress-strain curves from uniaxial extensiometry, particularly in the 0-0.4 range. Equivalent Young´s moduli of the reconstructed material properties from air-puff were 0.31, 0.58 and 0.48 MPa for the three polymer materials respectively which differed < 1% from those obtained from extensiometry. The simulations of the same material but different thickness resulted in similar reconstructed material properties. The air-puff reconstructed average equivalent Young´s modulus of the porcine corneas was 1.3 MPa, within 18% of that obtained from extensiometry. Air puff corneal deformation imaging with inverse finite element modeling can retrieve material properties of model hydrogel polymer corneas and real corneas, which are in good correspondence with those obtained from uniaxial extensiometry, suggesting that this is a promising technique to retrieve quantitative corneal biomechanical properties.

Accelerated versus conventional corneal collagen cross-linking in patients with keratoconus: an intrapatient comparative study.

PubMed

Sadoughi, Mohammad Mehdi; Einollahi, Bahram; Baradaran-Rafii, Alireza; Roshandel, Danial; Hasani, Hamidreza; Nazeri, Mehrdad

2018-02-01

To compare the outcomes of the conventional and accelerated corneal collagen cross-linking (CXL) in patients with bilateral progressive keratoconus (KC). Fifteen consecutive patients with bilateral progressive KC were enrolled. In each patient, the fellow eyes were randomly assigned to the conventional CXL (3 mW/cm 2 for 30 min) or accelerated CXL (ACXL) (9 mW/cm 2 for 10 min) groups. Manifest refraction; uncorrected and corrected distant visual acuity; maximum and mean keratometry; corneal hysteresis and corneal resistance factor; endothelial cell density and morphology; central corneal thickness; and wavefront aberrations were measured before and 12 months after the CXL. Manifest refraction spherical equivalent and refractive cylinder improved significantly only in conventional group. Uncorrected and corrected distant visual acuity did not change significantly in either group. Also there was no significant change in the maximum and mean keratometry after 12 months. There was significant decrease in central corneal thickness in both groups which was more prominent in conventional group. Endothelial cell density reduced only in the conventional group which was not statistically significant (P = 0.147). CH, CRF, and wavefront aberrations did not change significantly in either group. We did not observe any significant difference in the changes of the variables between the two groups. Accelerated CXL with 9 mW/cm 2 irradiation for 10 min had similar refractive, visual, keratometric, and aberrometric results and less adverse effects on the corneal thickness and endothelial cells as compared with the conventional method after 12 months follow-up. However, randomized clinical trials with longer follow-ups and larger sample sizes are needed.

Comparison of stromal corneal nerves between normal and keratoconus patients using confocal microscopy.

PubMed

Ramírez Fernández, M; Hernández Quintela, E; Naranjo Tackman, R

2014-08-01

To evaluate the differences in stromal corneal nerves between normal patients and keratoconus patients. A total of 140 eyes of 70 normal patients (group A) and 122 eyes of 87 keratoconus patients (group B) were examined with the confocal microscope, with a central scan of the total corneal thickness being taken. The morphology and thickness of the corneal stromal nerves were evaluated by using the Navis v. 3.5.0. software. Nerve thickness was obtained from the mean between the widest and the narrowest portions of each stromal nerve. Corneal stromal nerves were observed as irregular linear hyper-reflective structures with wide and narrow portions in all cases. Mean corneal stromal nerves thickness in group A was 5.7±1.7 (range from 3.3 to 10.4 μ), mean corneal stromal nerves thickness in group B was 7.2±1.9 (range from 3.5 to 12.0 μ). There was a statistical significant difference (P<.05) in stromal corneal nerves thickness between group A and group B. Stromal corneal nerves morphology was similar in both groups, but stromal nerves were thicker in keratoconus patients. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

THz and mm-Wave Sensing of Corneal Tissue Water Content: Electromagnetic Modeling and Analysis

PubMed Central

Taylor, Zachary D.; Garritano, James; Sung, Shijun; Bajwa, Neha; Bennett, David B.; Nowroozi, Bryan; Tewari, Priyamvada; Sayre, James; Hubschman, Jean-Pierre; Deng, Sophie; Brown, Elliott R.; Grundfest, Warren S.

2015-01-01

Terahertz (THz) spectral properties of human cornea are explored as a function of central corneal thickness (CCT) and corneal water content, and the clinical utility of THz-based corneal water content sensing is discussed. Three candidate corneal tissue water content (CTWC) perturbations, based on corneal physiology, are investigated that affect the axial water distribution and total thickness. The THz frequency reflectivity properties of the three CTWC perturbations were simulated and explored with varying system center frequency and bandwidths (Q-factors). The modeling showed that at effective optical path lengths on the order of a wavelength the cornea presents a lossy etalon bordered by air at the anterior and the aqueous humor at the posterior. The simulated standing wave peak-to-valley ratio is pronounced at lower frequencies and its effect on acquired data can be modulated by adjusting the bandwidth of the sensing system. These observations are supported with experimental spectroscopic data. The results suggest that a priori knowledge of corneal thickness can be utilized for accurate assessments of corneal tissue water content. The physiologic variation of corneal thickness with respect to the wavelengths spanned by the THz band is extremely limited compared to all other structures in the body making CTWC sensing unique amongst all proposed applications of THz medical imaging. PMID:26322247

The Favorable Effect of Mesenchymal Stem Cell Treatment on the Antioxidant Protective Mechanism in the Corneal Epithelium and Renewal of Corneal Optical Properties Changed after Alkali Burns.

PubMed

Cejka, Cestmir; Holan, Vladimir; Trosan, Peter; Zajicova, Alena; Javorkova, Eliska; Cejkova, Jitka

2016-01-01

The aim of this study was to examine whether mesenchymal stem cells (MSCs) and/or corneal limbal epithelial stem cells (LSCs) influence restoration of an antioxidant protective mechanism in the corneal epithelium and renewal of corneal optical properties changed after alkali burns. The injured rabbit corneas (with 0.25 N NaOH) were untreated or treated with nanofiber scaffolds free of stem cells, with nanofiber scaffolds seeded with bone marrow MSCs (BM-MSCs), with adipose tissue MSCs (Ad-MSCs), or with LSCs. On day 15 following the injury, after BM-MSCs or LSCs nanofiber treatment (less after Ad-MSCs treatment) the expression of antioxidant enzymes was restored in the regenerated corneal epithelium and the expressions of matrix metalloproteinase 9 (MMP9), inducible nitric oxide synthase (iNOS), α-smooth muscle actin (α-SMA), transforming growth factor-β1 (TGF-β1), and vascular endothelial factor (VEGF) were low. The central corneal thickness (taken as an index of corneal hydration) increased after the injury and returned to levels before the injury. In injured untreated corneas the epithelium was absent and numerous cells revealed the expressions of iNOS, MMP9, α-SMA, TGF-β1, and VEGF. In conclusion, stem cell treatment accelerated regeneration of the corneal epithelium, restored the antioxidant protective mechanism, and renewed corneal optical properties.

Corneal incision architecture after IOL implantation with three different injectors: an environmental scanning electron microscopy study.

PubMed

Mencucci, Rita; Favuzza, Eleonora; Salvatici, Maria Cristina; Spadea, Leopoldo; Allen, David

2018-02-01

To evaluate by Environmental Scanning Electron Microscopy (ESEM) the corneal incision architecture after intraocular lens (IOL) implantation in pig eyes, using manual, automated injectors or preloaded delivery systems. Twenty-four pig eyes underwent IOL implantation in the anterior chamber using three different injectors: manual (Monarch III) (n = 8), automated (AutoSert) (n = 8), or a preloaded system (UltraSert) (n = 8). Acrysof IQ IOLs, 21 Dioptres (D) (n = 12) and 27D (n = 12), were implanted through 2.2 mm clear corneal incisions. Incision width was measured using corneal calipers. The endothelial side of the incision was analyzed with ESEM. In each group, the final size of the corneal wound after IOL implantation, measured by calipers, was 2.3-2.4 mm. The incision architecture resulted more irregular in the Monarch group compared with the other injectors. In every group the 27D IOL-implanted specimens showed more alterations than in 21D IOL-implanted samples, and this was less evident in the UltraSert group. The Descemet tear length was higher in the Monarch group than AutoSert and UltraSert group. The automated and preloaded delivery systems provided a good corneal incision architecture; after high-power IOL implantation the incisions were more regular and less damaged with the preloaded system than with the other devices.

Comparison of Changes in Central Corneal Thickness During Corneal Collagen Cross-Linking, Using Isotonic Riboflavin Solutions With and Without Dextran, in the Treatment of Progressive Keratoconus.

PubMed

Zaheer, Naima; Khan, Wajid Ali; Khan, Shama; Khan, M Abdul Moqeet

2018-03-01

To compare intraoperative changes in central corneal thickness (CCT) during corneal cross-linking, using 2 different isotonic riboflavin solutions either with dextran or with hydroxy propyl methylcellulose, in the treatment of progressive keratoconus. In this retrospective study, we analyzed records of corneal thickness measurements, taken during various steps of cross-linking. Cross-linking was performed using either isotonic riboflavin with dextran (group A) or isotonic riboflavin with hydroxy propyl methylcellulose (without dextran) (group B). CCT measurements were recorded before and after epithelial removal, after saturation with respective isotonic riboflavin solution, after use of hypotonic riboflavin in selected cases, and after ultraviolet A (UV-A) application. A mixed-way analysis of variance was conducted on CCT readings within each group and between both groups, and p < 0.05 was considered significant. In group A (100 cases), after saturation with isotonic riboflavin, CCT was decreased by a mean of 51.4 μm (12.1%). In 64%, CCT was <400 μm and additional hypotonic riboflavin was used. After UV-A irradiation, CCT was decreased by a mean of 46.7 μm (11.4%). In group B (100 cases), after saturation with isotonic riboflavin, CCT was increased by a mean of 109.4 μm (26.1%). After UV-A exposure, CCT was increased by a mean of 59.2 μm (11.2%). There was a substantial main effect for time on CCT during corneal cross-linking (CXL), p < 0.001, within both groups. The main effect comparing CCT readings between groups A and B was also significant, p < 0.001. During cross-linking, isotonic riboflavin with dextran causes a significant decrease in corneal thickness, whereas dextran-free isotonic riboflavin causes a significant increase in corneal thickness, thus facilitating the procedure.

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.

Repeatability of Central Corneal Thickness Measurement Using Rotating Scheimpflug Camera in Dry and Normal Eyes.

PubMed

Lee, Jong-Hyuck; Kim, Jae Hyuck; Kim, Sun Woong

2017-02-27

To compare the repeatability of central corneal thickness (CCT) measurement using the Pentacam between dry eyes and healthy eyes, as well as to investigate the effect of artificial tears on CCT measurement. The corneal thicknesses of 34 patients with dry eye and 28 healthy subjects were measured using the Pentacam. One eye from each subject was assigned randomly to a repeatability test, wherein a single operator performed three successive CCT measurements time points-before and 5 min after instillation of one artificial teardrop. The repeatability of measurements was assessed using the coefficient of repeatability and the intraclass correlation coefficient. The coefficient of repeatability values of the CCT measurements in dry and healthy eyes were 24.36 and 10.69 μm before instillation, and 16.85 and 9.72 μm after instillation, respectively. The intraclass correlation coefficient was higher in healthy eyes than that of in dry eyes (0.987 vs. 0.891), and it had improved significantly in dry eyes (0.948) after instillation of one artificial teardrop. The CCT measurement fluctuated in dry eyes (repeated-measures analysis of variance, P<0.001), whereas no significant changes were detected in healthy eyes, either before or after artificial tear instillation. Central corneal thickness measurement is less repeatable in dry eyes than in healthy eyes. Artificial tears improve the repeatability of CCT measurements obtained using the Pentacam in dry eyes.

Proposal for a Novel Severity Grading System for Pterygia Based on Corneal Topographic Data.

PubMed

Miyata, Kazunori; Minami, Keiichiro; Otani, Atsushi; Tokunaga, Tadatoshi; Tokuda, Shouta; Amano, Shiro

2017-07-01

To propose a grading system of pterygium severity based on corneal higher-order irregularity (HOI) and to evaluate postoperative changes in corneal irregularity of the graded pterygia. In 268 eyes of 226 patients undergoing excision surgery of primary nasal pterygium, Placido corneal topography images were taken before and until 6 months after surgery. The best-corrected visual acuity (BCVA) and pterygium size with respect to the corneal diameter were also measured. HOI components within 1.0-, 3.0-, and 5.0-mm diameters were obtained using Fourier harmonic analysis of corneal topography data. With threshold levels when the HOIs for 3 diameters steeply increased, 4 levels of grading from 0 (mild) to 3 (severe) were determined. Associations of the grades with the preoperative surface regularity index (SRI), irregular components (IRRs) obtained from the 3.0-mm diameter Fourier analysis, and BCVA were examined. Time-course changes in the indexes after surgery were evaluated for each grade. There were 62, 65, 41, and 100 eyes in grades 0 to 3, respectively. Preoperatively, the SRI in grade 3 was significantly higher than in the other grades (P < 0.001), and the IRR and BCVA varied with the grade (P < 0.001). Between 1 and 6 months postoperatively, grade 3 pterygia showed significant changes in the SRI and IRR (P = 0.013 and 0.017, respectively), whereas there was no change after 3 months postoperatively in the SRI, IRR, and BCVA for all other grades. The proposed grading effectively classified the severity of pterygia and evaluated postoperative restoration of corneal irregularity. Using corneal topographic data allowed for objective evaluation of pterygium severity.

NK cells modulate the inflammatory response to corneal epithelial abrasion and thereby support wound healing

USDA-ARS?s Scientific Manuscript database

Natural killer cells are lymphocytes of the innate immune system that have crucial cytotoxic and regulatory roles in adaptive immunity and inflammation. Herein, we consider a role for these cells in corneal wound healing. After a 2-mm central epithelial abrasion of the mouse cornea, a subset of clas...

Evaluation of a new method for the measurement of corneal thickness in eye bank posterior corneal lenticules using Anterior Segment Optical Coherence Tomography.

PubMed

Amato, Domenico; Lombardo, Marco; Oddone, Francesco; Nubile, Mario; Colabelli Gisoldi, Rossella A M; Villani, Carlo M; Yoo, Sonia; Parel, Jean-Marie; Pocobelli, Augusto

2011-04-01

To preliminarily evaluate the repeatability of central corneal thickness (CCT) measurements performed with Anterior Segment Optical Coherence Tomography (AS-OCT) on eye bank posterior corneal lenticules. Six donor lenticules were created with a 350 μm head microkeratome (Moria, Antony, France). All donor tissues were stored at 4°C in Eusol-C solution (Alchimia S.r.l, Ponte S. Nicolò, Italy), without the anterior cornea lamella. The CCT of each lenticule, maintained in the glass phial, was measured using a commercial AS-OCT instrument (Visante, Carl Zeiss Meditec, Dublin, California, USA) and a specially designed adaptor immediately and 4, 24 and 48 hours after dissection. Immediately after AS-OCT, CCT values were measured with the ultrasound pachymetry method used at the Eye Bank. The mean donor cornea central thickness was 647±36 μm and 660 ± 38 μm (p=0.001) as measured by AS-OCT and ultrasound, respectively; immediately after dissection, CCT values of posterior lenticules were 235 ± 43 μm and 248 ± 44 μm, respectively (p=0.001). No statistically significant changes in CCT values of donor lenticules were assessed over the 48 h period with both methods. There was a high level of agreement, evidenced by Bland-Altman analysis, between the two methods of pachymetry. AS-OCT, with the corneal tissue in the vial, was revealed to be a repeatable and reliable method for measuring posterior donor lenticule central thickness. Lenticule CCT values measured with the investigational AS-OCT method were on average 10 μm thinner than those measured with the established ultrasound method.

Factors affecting the outcome of excimer laser photorefractive keratectomy: a preliminary multivariable regression analysis

NASA Astrophysics Data System (ADS)

Maguen, Ezra I.; Papaioannou, Thanassis; Nesburn, Anthony B.; Salz, James J.; Warren, Cathy; Grundfest, Warren S.

1996-05-01

Multivariable regression analysis was used to evaluate the combined effects of some preoperative and operative variables on the change of refraction following excimer laser photorefractive keratectomy for myopia (PRK). This analysis was performed on 152 eyes (at 6 months postoperatively) and 156 eyes (at 12 months postoperatively). The following variables were considered: intended refractive correction, patient age, treatment zone, central corneal thickness, average corneal curvature, and intraocular pressure. At 6 months after surgery, the cumulative R2 was 0.43 with 0.38 attributed to the intended correction and 0.06 attributed to the preoperative corneal curvature. At 12 months, the cumulative R2 was 0.37 where 0.33 was attributed to the intended correction, 0.02 to the preoperative corneal curvature, and 0.01 to both preoperative corneal thickness and to the patient age. Further model augmentation is necessary to account for the remaining variability and the behavior of the residuals.

Effect of 0.4% benoxinate hydrochloride on corneal sensitivity, measured using the non-contact corneal aesthesiometer (NCCA).

PubMed

Murphy, P J; Blades, K J; Patel, S

1997-12-01

The Non-Contact Corneal Aesthesiometer (NCCA) was used to monitor the effect of topical anesthesia on corneal sensitivity loss and recovery. In a single masked randomized study, one drop of nonpreserved 0.4% benoxinate hydrochloride was instilled in either the right, left, or both eyes of 20 subjects on separate days, and measurements were made of the central corneal sensitivity in the right eye over a 60-min period. As controls, 10 subjects were retested, without any anesthetic instillation, over the same time period. No significant differences were found between these two benoxinate treatments, nor between the contralateral treatment and controls. Results indicate that there is no contralateral effect of benoxinate anesthesia, and that full recovery does not occur until 60 min after instillation. No effect on the depth and duration of anesthesia was found for iris color.

Novel monitoring of corneal surface hydration during photorefractive keratectomy using pulsed photothermal radiometry: in-vitro study

NASA Astrophysics Data System (ADS)

Kawauchi, Satoko; Matsuyama, Hiroko; Obara, Minoru; Ishihara, Miya; Arai, Tsunenori; Kikuchi, Makoto; Katoh, Masayoshi

1997-05-01

We developed novel monitoring methodology for corneal surface hydration during photorefractive keratectomy (PRK) in order to solve undercorrection issue at the central part of cornea (Central island). We employed pulsed photothermal radiometry to monitor corneal surface hydration. We performed two experiments; gelatin gel experiments and porcine cornea experiments in vitro. In the case of the gelatin gel experiments, the e-folding decay time of transient infrared radiation waveform from the ArF laser irradiated surface was prolonged from 420 microsecond(s) to 30 ms with decreasing gelatin density from 15% to 0.15%. These measured e-folding decay times were good agreements with theoretical calculations. Using porcine cornea, we observed the e-folding decay time increase during the series of ArF excimer laser irradiations. Our method may be available to know ablation efficiency change to improve the controllability of refractive correction on the PRK.

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.

Regulation of Corneal Stroma Extracellular Matrix Assembly

PubMed Central

Chen, Shoujun; Mienaltowski, Michael J.; Birk, David E.

2014-01-01

The transparent cornea is the major refractive element of the eye. A finely controlled assembly of the stromal extracellular matrix is critical to corneal function, as well as in establishing the appropriate mechanical stability required to maintain corneal shape and curvature. In the stroma, homogeneous, small diameter collagen fibrils, regularly packed with a highly ordered hierarchical organization, are essential for function. This review focuses on corneal stroma assembly and the regulation of collagen fibrillogenesis. Corneal collagen fibrillogenesis involves multiple molecules interacting in sequential steps, as well as interactions between keratocytes and stroma matrix components. The stroma has the highest collagen V:I ratio in the body. Collagen V regulates the nucleation of protofibril assembly, thus controlling the number of fibrils and assembly of smaller diameter fibrils in the stroma. The corneal stroma is also enriched in small leucine-rich proteoglycans (SLRPs) that cooperate in a temporal and spatial manner to regulate linear and lateral collagen fibril growth. In addition, the fibril-associated collagens (FACITs) such as collagen XII and collagen XIV have roles in the regulation of fibril packing and inter-lamellar interactions. A communicating keratocyte network contributes to the overall and long-range regulation of stromal extracellular matrix assembly, by creating micro-domains where the sequential steps in stromal matrix assembly are controlled. Keratocytes control the synthesis of extracellular matrix components, which interact with the keratocytes dynamically to coordinate the regulatory steps into a cohesive process. Mutations or deficiencies in stromal regulatory molecules result in altered interactions and deficiencies in both transparency and refraction, leading to corneal stroma pathobiology such as stromal dystrophies, cornea plana and keratoconus. PMID:25819456

Effect of marking pens on femtosecond laser-assisted flap creation.

PubMed

Ide, Takeshi; Kymionis, George D; Abbey, Ashkan M; Yoo, Sonia H; Culbertson, William W; O'Brien, Terrence P

2009-06-01

To compare the ease of the flap lift after central corneal marking with 2 types of marking pens after femtosecond laser-assisted flap creation in laser in situ keratomileusis. Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. Porcine eyes were prepared for flap creation with a femtosecond laser (IntraLase). The eyes were assigned to 1 of 4 groups. After the femtosecond laser treatment, the difficulty of flap lifting the 4 groups was compared. Twelve porcine eyes, 3 in each group, were evaluated. In the 2 groups in which an oil-based pen was used, the corneal flap could not be lifted. In the 2 groups in which a water-based pen was used, the corneal flap was easily lifted. Oil-based ink may reduce the ability of the femtosecond laser to penetrate the cornea. The resultant corneal flap may require aggressive manipulation to be lifted. When used to mark the center of the cornea before flap creation, water-based ink provided greater ease of corneal flap lifting than oil-based ink. Because the marking is located over the center of the pupil, any alteration of the cornea in this area from aggressive flap lifting may result in substantial visual loss. Therefore, the use of an oil-based ink to mark the central cornea must be avoided to prevent traumatic irregularities of the flap stroma.

Corneal changes with accommodation using dual Scheimpflug photography.

PubMed

Sisó-Fuertes, Irene; Domínguez-Vicent, Alberto; del Águila-Carrasco, Antonio; Ferrer-Blasco, Teresa; Montés-Micó, Robert

2015-05-01

To assess whether corneal parameters and aberrations are affected by accommodation. Optics Department, University of Valencia, Valencia, Spain. Prospective cross-sectional study. The Galilei G4 dual Scheimpflug device was used to obtain data on the anterior and posterior axial curvatures, total corneal power (TCP), and corneal pachymetry from 3 corneal zones (central: 0.0 up to 4.0 mm; paracentral or mid: 4.0 up to 7.0 mm; peripheral: 7.0 up to 10.0 mm) in young emmetropic eyes in the unaccommodated and 4 accommodated states (from -1.0 to -4.0 diopters [D] in 1.0 D steps). The 2nd-, 3rd-, and 4th-order aberrations as well as the root mean square (RMS) were also determined for the entire cornea at the same accommodative demands. The study evaluated 7 subjects (12 eyes). No significant changes in any measured parameter were found during accommodation for any corneal zone (P > .05). Statistically significant differences were found in the various corneal zones when it was assumed they were constant with accommodation (P < .01). A stable linear trend with accommodation was also found for corneal aberrations, although individual variations existed because of the high standard deviation values. Different parameters in various zones of the cornea as well as corneal aberrations were stable during accommodation. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Bilateral ring-shaped intrastromal opacities after corneal cross-linking for keratoconus.

PubMed

Camesasca, Fabrizio I; Vinciguerra, Paolo; Seiler, Theo

2011-12-01

To report a case of bilateral, ring-shaped, intrastromal corneal opacities after corneal cross-linking (CXL) for progressive keratoconus. A 21-year-old man with bilateral, progressive keratoconus underwent CXL with riboflavin 0.1% and ultraviolet A (UVA) light in the right eye and, 6 months later, in the left eye. One day after CXL, the right eye showed a sharply demarcated white ring in the corneal periphery. The ring involved the superficial stroma at 2 mm from the limbus, extended from 1 to 11 o'clock, and was 1.5-mm wide. Corneal topography showed marked central flattening. Six months after treatment, a residual, faint, ring-shaped opacity remained, with a decrease in corneal ectasia. Cross-linking was then performed in the left eye. Different ultraviolet devices were used in the two eyes. On postoperative day 1, the left eye also showed a white ring of stromal opacity. Scheimpflug imaging showed corneal stromal contraction in the zone of whitening. At final examination, >1 year after surgery, corrected visual acuity was 0.00 logMAR with cylinder of 2.00 diopters in both eyes. The bilateral intrastromal corneal changes were innocuous in the long-term, with preservation of good visual acuity and successful stabilization of progressive keratoconus.

Sutureless Corneal Transplantation Apparatus And Method

DOEpatents

Rowsey, J. James

1996-12-17

An eye with a cornea repaired without sutures comprising a donor material in the shape of a partial sphere having a generally central extent, the central extent being of the size and shape of the central portion of a cornea of an eye, the central extent having a periphery of a fixed diameter with an exterior surface in a convex configuration and an interior surface in a concave configuration and with an essentially common thickness throughout, the central extent having a plurality of corneal flaps extending radially from the periphery of the central extent, the flaps having exterior surfaces as a continuation of the exterior surface of the central extent; and a recipient eye in the shape of a partial sphere having a circular aperture in the cornea at its central portion, the central aperture being of a size and shape essentially that of the periphery of the central extent of the donor material, the aperture being of a common thickness at the periphery of the aperture, the central portion having pockets and with the central extent of the donor material located within the aperture of the recipient eye and with the flaps of the central extent being imbricated into the pockets of the recipient eye.

Inflammation and the Nervous System: The Connection in the Cornea in Patients with Infectious Keratitis

PubMed Central

Cruzat, Andrea; Witkin, Deborah; Baniasadi, Neda; Zheng, Lixin; Ciolino, Joseph B.; Jurkunas, Ula V.; Chodosh, James; Pavan-Langston, Deborah; Dana, Reza

2011-01-01

Purpose. To study the density and morphologic characteristics of epithelial dendritic cells, as correlated to subbasal corneal nerve alterations in acute infectious keratitis (IK) by in vivo confocal microscopy (IVCM). Methods. IVCM of the central cornea was performed prospectively in 53 eyes with acute bacterial (n = 23), fungal (n = 13), and Acanthamoeba (n = 17) keratitis, and in 20 normal eyes, by using laser in vivo confocal microscopy. Density and morphology of dendritic-shaped cells (DCs) of the central cornea, corneal nerve density, nerve numbers, branching, and tortuosity were assessed and correlated. It should be noted that due to the “in vivo” nature of the study, the exact identity of these DCs cannot be specified, as they could be monocytes or tissue macrophages, but most likely dendritic cells. Results. IVCM revealed the presence of central corneal DCs in all patients and controls. The mean DC density was significantly higher in patients with bacterial (441.1 ± 320.5 cells/mm2; P < 0.0001), fungal (608.9 ± 812.5 cells/mm2; P < 0.0001), and Acanthamoeba keratitis (1000.2 ± 1090.3 cells/mm2; P < 0.0001) compared with controls (49.3 ± 39.6 cells/mm2). DCs had an increased size and dendrites in patients with IK. Corneal nerves were significantly reduced in eyes with IK compared with controls across all subgroups, including nerve density (674.2 ± 976.1 vs. 3913.9 ± 507.4 μm/frame), total nerve numbers (2.7 ± 3.9 vs. 20.2 ± 3.3), main trunks (1.5 ± 2.2 vs. 6.9 ± 1.1), and branching (1.2 ± 2.0 vs. 13.5 ± 3.1; P < 0.0001). A strong association between the diminishment of corneal nerves and the increase of DC density was observed (r = −0.44; P < 0.0005). Conclusions. IVCM reveals an increased density and morphologic changes of central epithelial DCs in infectious keratitis. There is a strong and significant correlation between the increase in DC numbers and the decreased subbasal corneal nerves, suggesting a potential interaction between the immune and nervous system in the cornea. PMID:21460259

Ocular forward light scattering and corneal backward light scattering in patients with dry eye.

PubMed

Koh, Shizuka; Maeda, Naoyuki; Ikeda, Chikako; Asonuma, Sanae; Mitamura, Hayato; Oie, Yoshinori; Soma, Takeshi; Tsujikawa, Motokazu; Kawasaki, Satoshi; Nishida, Kohji

2014-09-18

To evaluate ocular forward light scattering and corneal backward light scattering in patients with dry eye. Thirty-five eyes in 35 patients with dry eye and 20 eyes of 20 healthy control subjects were enrolled. The 35 dry eyes were classified into two groups according to whether superficial punctate keratopathy in the central 6-mm corneal zone (cSPK) was present or not. Ocular forward light scattering was quantified with a straylight meter. Corneal backward light scattering from the anterior, middle, and posterior corneal parts was assessed with a corneal densitometry program using the Scheimpflug imaging system. Both dry eye groups had significantly higher intraocular forward light scattering than the control group (both P<0.05). The dry eye group with cSPK had significantly higher values in anterior and total corneal backward light scattering than the other two groups. Moderate positive correlations were observed between the cSPK score and corneal backward light scattering from the anterior cornea (R=0.60, P<0.001) and corneal backward light scattering from the total cornea (R=0.54, P<0.001); however, no correlation was found between cSPK score and ocular forward light scattering (R=0.01, P=0.932). Ocular forward light scattering and corneal backward light scattering from the anterior cornea were greater in dry eyes than in normal eyes. Increased corneal backward light scattering in dry eye at least partially results from cSPK overlying the optical zone. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Comparison of corneal thickness after the instillation of topical anesthetics: proparacaine versus oxybuprocaine.

PubMed

Nam, Sang Min; Lee, Hyung Keun; Kim, Eung Kweon; Seo, Kyoung Yul

2006-01-01

To compare changes in human corneal thickness after the instillation of proparacaine with those after oxybuprocaine instillation with time over a period of 10 minutes. Eighteen healthy young participants were recruited. Proparacaine was used in the right eye and oxybuprocaine in the left. Right and left baseline corneal thicknesses were measured every 30 seconds for 10 minutes using a noncontact specular microscope by 1 observer. Baseline corneal thickness was defined as the average of all values taken over 10 minutes. Changes in corneal thickness were measured every 20 seconds for 10 minutes after the administration of 1 drop of 0.5% proparacaine onto the right cornea and 1 drop of 0.4% oxybuprocaine onto the left cornea. Mean baseline right cornea thickness was 531 +/- 45 microm, and that of the left cornea was 531 +/- 42 microm. The corneal thickness after proparacaine increased by 8.6 microm ( approximately 4.5-12.6 microm, 95% CI) and then returned to baseline within 80 seconds. Corneal thickness after applying oxybuprocaine increased by 7.7 microm (3.6-11.2 microm, 95% CI) and then returned to baseline within 80 seconds. There was a second transient increase about 5 minutes later after proparacaine instillation but no additional transient increase after oxybuprocaine instillation. Oxybuprocaine is similar to proparacaine in terms of the severity of its effect on corneal thickness. Corneal thickness instability may occur for 5 minutes after proparacaine administration. Changes in corneal thickness after topical anesthetic instillation should be considered when performing measurements for refractive surgery or central corneal thickness in glaucoma patients.

Anterior segment changes in rabbits after experimental aqueous replacement with various amounts of different perfluorocarbon liquids.

PubMed

Stolba, U; Krepler, K; Velikay, M; Binder, S

1999-06-01

We evaluated biomicroscopic and histological effects on the anterior segment in the rabbit eye after temporary aqueous substitution with various amounts (0.2 cc and 0.025 cc) of perfluorodecaline (PFD) and perfluorophenanthrene (PFP). A quantity of 0.2 cc of the two perfluorocarbon (PFC) liquids was exchanged simultaneously with about 50% of the aqueous in 15 rabbit eyes each for periods of 1, 2, or 4 weeks. At these points some eyes were enucleated for histological examination. After 2 and 4 weeks the substances were removed from the remaining eyes, which were then followed up for 8-10 weeks. In an additional 8 eyes, 0.025 cc PFD or PFP was injected and left for 8 weeks. Four eyes received balanced salt solution and served as controls. Beside biomicroscopic evaluation and measurement of the intraocular pressure, endothelial cell counts and corneal pachymetry were performed regularly during follow-up. The postoperative results were well comparable for PFD and PFP eyes. Within the first 2 weeks postoperatively corneal edema with endothelial cell loss was observed in both groups. Thereafter regression of the edema started independently of whether the substances were removed or not. IOP was not elevated at any time. At the end of follow-up central corneal thickness was the same as initially. In the inferior corneal endothelium cell density decreased to 45-50% of that in normals. Histologically, vacuoles in the iris and chamber angle were found inferiorly after 4 weeks. Chamber angle closures were present between 5 and 7 o'clock in those eyes where the PFC liquids had been removed after 2 and 4 weeks. Eyes with 0.025 cc PFD or PFP droplets showed vacuolization of the inferior trabecular meshwork 8 weeks postoperatively that was comparable with eyes which had a 50% aqueous replacement for 4 weeks. Control eyes remained unchanged in all aspects. Anterior segment damage caused by PFC liquids is a contact-dependent effect seen in the early observation period. Experimentally there was no difference between the products used or between 2 and 4 weeks' duration of the tamponade.

Corneal thickness of eyes with unilateral age-related macular degeneration.

PubMed

Arikan, Sedat; Ersan, Ismail; Kara, Selcuk; Gencer, Baran; Korkmaz, Safak; Vural, Azer Sara

2015-01-01

To compare the central corneal thicknesses (CCT), peripheral corneal thicknesses, and corneal volumes (CV) of the 2 eyes of patients with unilateral age-related macular degeneration (AMD). Twenty patients who were diagnosed with unilateral AMD were included in this prospective study for the purpose of making comparison between the diseased and healthy eyes. Optical coherence tomography and fundus fluorescein angiography imaging were applied to all patients in order to confirm and reveal the presence of unilateral AMD. Then, the measurements of CCT, peripheral corneal thickness measured 4 mm distant from the center of the cornea (4 mm CT), and CV of each eye of these patients were obtained through the rotating Scheimpflug corneal topographer. Wilcoxon signed-rank test did not demonstrate a statistically significant difference between the 2 eyes of patients with unilateral AMD when we compared the CCT and CV of diseased and healthy eyes (p>0.05). However, 4 mm CT of the diseased eyes of these patients were statistically significantly thicker than the healthy eyes (p<0.05). The significant difference in terms of 4 mm CT between the diseased and healthy eyes of patients with unilateral AMD may demonstrate the possible effect of peripheral corneal thickness on the development of AMD.

Central corneal thickness in glaucoma.

PubMed

Sng, Chelvin C A; Ang, Marcus; Barton, Keith

2017-03-01

The purpose of this review is to summarize the role of central corneal thickness (CCT) in the clinical management of a glaucoma patient. The prognostic value of CCT is well recognized in patients with ocular hypertension. However, its predictive value in other glaucoma suspects and patients with established glaucoma is less certain. Tonometry artefacts can result from variations in CCT. However, an adequately validated correction algorithm for Goldmann applanation tonometry measurements does not exist. Newer methods of tonometry are potentially less influenced by CCT but are limited in their clinical use. There may also be biological and genetic associations between corneal thickness and glaucoma. Demographics, environmental factors, glaucoma treatment and the measurement device used have a significant influence on CCT, and should be considered when interpreting the effect of cornea thickness in patients with glaucoma. New measurements of the biomechanical properties of the cornea are likely to be better approximations of the globe biomechanics than CCT, but these require further evaluation. The clinical significance of CCT is well recognized in the context of glaucoma diagnosis and management, though the extent of its importance remains debatable. Corneal biomechanical properties may be more significantly associated with glaucoma than CCT.

Corneal densitometry and its correlation with age, pachymetry, corneal curvature, and refraction.

PubMed

Garzón, Nuria; Poyales, Francisco; Illarramendi, Igor; Mendicute, Javier; Jáñez, Óscar; Caro, Pedro; López, Alfredo; Argüeso, Francisco

2017-12-01

To determine normative corneal densitometry values in relation to age, sex, refractive error, corneal thickness, and keratometry, measured using the Oculus Pentacam system. Three hundred and thirty-eight healthy subjects (185 men; 153 women) with no corneal disease underwent an exhaustive ocular examination. Corneal densitometry was expressed in standardized grayscale units (GSU). The mean corneal densitometry over the total area was 16.46 ± 1.85 GSU. The Pearson correlation coefficient for total densitometry was r = 0.542 (p < 0.001). Statistically significant differences were found between men and women for the total area (p = 0.006), with readings of 16.22 ± 1.54 GSU and 16.60 ± 1.83 GSU, respectively. When the cornea was divided into layers of different depths, a significant correlation was found for all layers and age: r = 0.447 (p < 0.001), r = 0.563 (p < 0.001), and r = 0.520 (p < 0.001) for the anterior, central, and posterior layers, respectively. However, when the cornea was divided into concentric annuli starting from the center of the cornea, densitometry was strongly correlated only with age in the 6-10-mm annulus (p < 0.001). Neither mean keratometry nor spherical equivalent was correlated with corneal densitometry in any zone of the cornea (p > 0.05). This is the first report of normative corneal densitometry values in relation to keratometry, corneal thickness, and spherical equivalent measured with the latest Oculus Pentacam software. Corneal densitometry increases with age, but corneal keratometry and refractive parameters do not affect light scattering in the human cornea.

Evaluation of Human Corneal Lenticule Quality After SMILE With Different Cap Thicknesses Using Scanning Electron Microscopy.

PubMed

Weng, Shengbei; Liu, Manli; Yang, Xiaonan; Liu, Fang; Zhou, Yugui; Lin, Haiqin; Liu, Quan

2018-01-01

To evaluate the surface characteristics of lenticules created by small-incision lenticule extraction (SMILE) with different cap thicknesses. This prospective study included 20 consecutive patients who underwent bilateral SMILE. Surface regularity of the extracted corneal lenticule was analyzed using scanning electron microscopy (SEM) combined with 2 methods: qualitative and quantitative regularity. Qualitative regularity of SEM images was graded by masked observers using an established scoring system. Quantitative regularity of SEM images was assessed by counting the total number and areas of tissue bridges using Image-Pro Plus software. Four different cap thickness of 120, 130, 140, and 150 μm were compared. Refractive outcomes of patients were measured at baseline and 1 month after surgery. As 10 specimens were not analyzable, only 30 eyes were included. Postoperatively, all eyes had postoperative uncorrected distance visual acuity of 20/20 or better; 43% had an unchanged corrected distance visual acuity; 43% gained 1 line; 10% lost 1 line. Ultrastructurally, surface irregularity was primarily caused by tissue bridges. The average surface regularity score obtained was 10.87 ± 2.40 for 120 μm, 10.78 ± 2.60 for 130 μm, 8.76 ± 2.16 for 140 μm, and 8.70 ± 2.66 for 150 μm (P < 0.001). The total number and areas of tissue bridges of 120 to 130 μm were significantly less than 140 to 150 μm (P < 0.05). Surface regularity decreased as cap thickness increased (P < 0.05). There is smoother appearance of the lenticular surface as seen through SEM when a thin cap is created compared with a thick cap qualitatively and quantitatively.

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.

Alcohol-assisted debridement in PRK with intraoperative mitomycin C.

PubMed

Nassiri, Nader; Sheibani, Kourosh; Safi, Sare; Haghnegahdar, Maryam; Nassiri, Saman; Panahi, Nekoo; Mehravaran, Shiva; Nassiri, Nariman

2014-09-01

To compare corneal stromal and endothelial cells after photorefractive keratectomy with intraoperative mitomycin C in alcohol-assisted versus mechanical epithelial debridement using confocal microscopy. This prospective randomized comparative study was performed on 88 eyes (44 patients) with myopia up to -6.00 diopters. The right eye of each patient was randomly assigned to either mechanical or alcohol-assisted groups, and the left eye was assigned to the alternate group. Confocal microscopy was performed preoperatively and at 3 months postoperatively. The main outcome measures were epithelial thickness; number of keratocytes in the anterior, mid-, and posterior stroma; and characteristics of the central corneal endothelial cells in terms of density, mean cell area, and polymegathism and hexagonality. Three months after surgery, no statistically significant difference was noted between the study groups in terms of epithelial thickness. We also found no statistically significant difference in central corneal endothelial cells regarding cell density, mean cell area, hexagonality, or polymegathism. Compared with baseline values, the density of mid- and posterior stromal keratocytes showed no significant change in either group, whereas it decreased significantly in the anterior stroma in both groups 3 months after surgery. We found that the adverse effects of photorefractive keratectomy with mitomycin C on central corneal endothelial cells were comparable between the mechanical and alcohol-assisted epithelial debridement groups and the significant decrease in postoperative keratocyte density in anterior stroma was comparable between the two groups. The choice of their application could be left to the discretion of the ophthalmologist.

Effects of Prolonged Reading on Dry Eye.

PubMed

Karakus, Sezen; Agrawal, Devika; Hindman, Holly B; Henrich, Claudia; Ramulu, Pradeep Y; Akpek, Esen K

2018-04-25

To demonstrate the effects of prolonged silent reading on tear film and ocular surface parameters. Prospective, observational clinical study. A total of 177 patients with dry eye and 34 normal controls aged 50 years and older. After evaluating symptoms using the Ocular Surface Disease Index (OSDI) questionnaire, the following tests were performed in consecutive order: automated noninvasive tear break-up time (TBUT), surface asymmetry and regularity indices, Schirmer's testing without anesthesia, corneal staining using fluorescein, and conjunctival staining using lissamine green. The participants were then asked to read a 30-minute validated passage silently. The tests were repeated after the reading task. Changes in tear film and ocular surface parameters after reading. All parameters, with the exception of surface asymmetry index, worsened after the reading task in patients with dry eye and in controls. The worsening reached a statistical significance for corneal and conjunctival staining in the dry eye group (P < 0.001) and for corneal staining in the control group (P < 0.01). At baseline, OSDI scores correlated only with corneal and conjunctival staining scores (r = 0.19, P = 0.006 and r = 0.27, P < 0.001). Among postreading measurements, baseline OSDI scores correlated with TBUT (r = -0.15, P = 0.03) in addition to corneal and conjunctival staining (r = 0.25, P < 0.001 and r = 0.22, P = 0.001). Changes in TBUT and Schirmer's test correlated significantly with their respective baseline values (r = -0.61, P < 0.001 and r = -0.44, P < 0.001), indicating that the more unstable the tear film and the lower the aqueous tear secretion, the worse they became after the prolonged reading task. Worsening in corneal staining directly correlated with the baseline conjunctival staining (r = 0.17, P = 0.02) and surface regularity index (r = 0.21, P = 0.01). Evaluating tear film and ocular surface parameters at rest may miss clinical findings brought about by common everyday tasks such as reading, leading to discordance between patient-reported symptoms and clinician-observed signs. Quantifying dry eye after visually straining activities such as prolonged silent reading may help better understand patient symptomatology. Copyright © 2018 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Consistency of corneal sublayer thickness measurements using Fourier-domain optical coherence tomography after phacoemulsification.

PubMed

López-Miguel, Alberto; Calabuig-Goena, María; Marqués-Fernández, Victoria; Fernández, Itziar; Alió, Jorge L; Maldonado, Miguel J

2016-11-04

To assess the reliability of corneal epithelial thickness (CET), nonepithelial central corneal thickness (NECCT), and central corneal thickness (CCT) measurements using Cirrus high-definition optical coherence tomography (HD-OCT) in patients who did and did not undergo cataract surgery. Forty patients who underwent uneventful phacoemulsification and 40 healthy participants were recruited to evaluate the intraobserver repeatability and interobserver reproducibility of CET, NECCT, and CCT measurements using Cirrus HD-OCT. To analyze repeatability, one examiner obtained 5 consecutive scans in each participant; for interobserver reproducibility, another examiner randomly obtained another scan. Within-subject standard deviation, coefficient of variation (CV), limits of agreement, and intraclass correlation coefficient (ICC) data were obtained. For intraobserver repeatability, the intrasession CV (CVw) and ICC values of the CET in the operated and nonoperated groups were 3.7% and 0.80 and 3.8% and 0.73, respectively; for NECCT, 0.7% and 0.98 and 0.8% and 0.97; and for CCT, 0.6% and 0.99 and 0.7% and 0.98. For interobserver reproducibility, the CVw and ICC values for the CET in the operated and nonoperated groups were 2.6% and 0.82 and 2.3% and 0.62, respectively; for NECCT, 0.7% and 0.98 and 0.5% and 0.98; and for CCT, 0.5% and 0.99 and 0.4% and 0.99. The corneal sublayer thickness can be measured reliably using Cirrus HD-OCT in patients who underwent cataract surgery and elderly participants; however, the CET consistency is poorer than the NECCT. Corneal epithelial thickness modifications exceeding 4% reflect true thickness changes instead of random error variations using HD-OCT.

Recovery of the sub-basal nerve plexus and superficial nerve terminals after corneal epithelial injury in mice.

PubMed

Downie, Laura E; Naranjo Golborne, Cecilia; Chen, Merry; Ho, Ngoc; Hoac, Cam; Liyanapathirana, Dasun; Luo, Carol; Wu, Ruo Bing; Chinnery, Holly R

2018-06-01

Our aim was to compare regeneration of the sub-basal nerve plexus (SBNP) and superficial nerve terminals (SNT) following corneal epithelial injury. We also sought to compare agreement when quantifying nerve parameters using different image analysis techniques. Anesthetized, female C57BL/6 mice received central 1-mm corneal epithelial abrasions. Four-weeks post-injury, eyes were enucleated and processed for PGP9.5 to visualize the corneal nerves using wholemount immunofluorescence staining and confocal microscopy. The percentage area of the SBNP and SNT were quantified using: ImageJ automated thresholds, ImageJ manual thresholds and manual tracings in NeuronJ. Nerve sum length was quantified using NeuronJ and Imaris. Agreement between methods was considered with Bland-Altman analyses. Four-weeks post-injury, the sum length of nerve fibers in the SBNP, but not the SNT, was reduced compared with naïve eyes. In the periphery, but not central cornea, of both naïve and injured eyes, nerve fiber lengths in the SBNP and SNT were strongly correlated. For quantifying SBNP nerve axon area, all image analysis methods were highly correlated. In the SNT, there was poor correlation between manual methods and auto-thresholding, with a trend towards underestimating nerve fiber area using auto-thresholding when higher proportions of nerve fibers were present. In conclusion, four weeks after superficial corneal injury, there is differential recovery of epithelial nerve axons; SBNP sum length is reduced, however the sum length of SNTs is similar to naïve eyes. Care should be taken when selecting image analysis methods to compare nerve parameters in different depths of the corneal epithelium due to differences in background autofluorescence. Copyright © 2018 Elsevier Ltd. All rights reserved.

Material Properties from Air Puff Corneal Deformation by Numerical Simulations on Model Corneas

PubMed Central

Dorronsoro, Carlos; de la Hoz, Andrés; Marcos, Susana

2016-01-01

Objective To validate a new method for reconstructing corneal biomechanical properties from air puff corneal deformation images using hydrogel polymer model corneas and porcine corneas. Methods Air puff deformation imaging was performed on model eyes with artificial corneas made out of three different hydrogel materials with three different thicknesses and on porcine eyes, at constant intraocular pressure of 15 mmHg. The cornea air puff deformation was modeled using finite elements, and hyperelastic material parameters were determined through inverse modeling, minimizing the difference between the simulated and the measured central deformation amplitude and central-peripheral deformation ratio parameters. Uniaxial tensile tests were performed on the model cornea materials as well as on corneal strips, and the results were compared to stress-strain simulations assuming the reconstructed material parameters. Results The measured and simulated spatial and temporal profiles of the air puff deformation tests were in good agreement (< 7% average discrepancy). The simulated stress-strain curves of the studied hydrogel corneal materials fitted well the experimental stress-strain curves from uniaxial extensiometry, particularly in the 0–0.4 range. Equivalent Young´s moduli of the reconstructed material properties from air-puff were 0.31, 0.58 and 0.48 MPa for the three polymer materials respectively which differed < 1% from those obtained from extensiometry. The simulations of the same material but different thickness resulted in similar reconstructed material properties. The air-puff reconstructed average equivalent Young´s modulus of the porcine corneas was 1.3 MPa, within 18% of that obtained from extensiometry. Conclusions Air puff corneal deformation imaging with inverse finite element modeling can retrieve material properties of model hydrogel polymer corneas and real corneas, which are in good correspondence with those obtained from uniaxial extensiometry, suggesting that this is a promising technique to retrieve quantitative corneal biomechanical properties. PMID:27792759

Comparison of Central Corneal Thickness Measured by Standard Ultrasound Pachymetry, Corneal Topography, Tono-Pachymetry and Anterior Segment Optical Coherence Tomography.

PubMed

González-Pérez, Javier; Queiruga Piñeiro, Juan; Sánchez García, Ángelx; González Méijome, José Manuel

2018-04-10

To compare central corneal thickness (CCT) measured by standard ultrasound pachymetry (USP), and three non-contact devices in healthy eyes. A cross-sectional study of CCT measurement in 52 eyes of 52 healthy volunteers was done by a single examiner at Ocular Surface and Contact Lens Laboratory. Three consecutive measurements were done by standard USP, non-contact tono-pachymeter, Pentacam corneal topographer, and Anterior Segment Optical Coherence Tomography (AS-OCT). The mean values were used for assessment. The results were compared using multivariate ANOVA, linear regression, and Pearson correlation. Agreement among the devices was analyzed using mean differences and Bland-Altman analysis with 95% limits of agreement (LoA). Finally, reliability was analyzed using intraclass correlation coefficient (ICC). Mean CCT by ultrasound pachymeter, tono-pachymeter, corneal topographer and AS-OCT were 558.9 ± 31.2 µm, 525.8 ± 43.1 µm, 550.4 ± 30.5 µm, and 545.9 ± 30.5 µm respectively. There was a significant positive correlation between AS-OCT and USP (Pearson correlation = 0.957, p < 0.001), corneal topography and USP (Pearson correlation = 0.965, p < 0.001), and corneal topography and AS-OCT (Pearson correlation = 0.965, p < 0.001). There was a lower correlation between CT-1P tono-pachymeter and the other three modalities. Intraclass correlation coefficients show an excellent reliability between pairs except for CT-1P against the other three instruments that were found moderate. CT-1P tono-pachymeter underestimates CCT measurements compared to Scheimpflug system, AS-OCT device, and USP. Mean CCT among USP, Pentacam and AS-OCT were comparable and had significant linear correlations. In clinical practice, these three modalities could be interchangeable in healthy patients.

Optimization of human corneal endothelial cell culture: density dependency of successful cultures in vitro.

PubMed

Peh, Gary S L; Toh, Kah-Peng; Ang, Heng-Pei; Seah, Xin-Yi; George, Benjamin L; Mehta, Jodhbir S

2013-05-03

Global shortage of donor corneas greatly restricts the numbers of corneal transplantations performed yearly. Limited ex vivo expansion of primary human corneal endothelial cells is possible, and a considerable clinical interest exists for development of tissue-engineered constructs using cultivated corneal endothelial cells. The objective of this study was to investigate the density-dependent growth of human corneal endothelial cells isolated from paired donor corneas and to elucidate an optimal seeding density for their extended expansion in vitro whilst maintaining their unique cellular morphology. Established primary human corneal endothelial cells were propagated to the second passage (P2) before they were utilized for this study. Confluent P2 cells were dissociated and seeded at four seeding densities: 2,500 cells per cm2 ('LOW'); 5,000 cells per cm2 ('MID'); 10,000 cells per cm2 ('HIGH'); and 20,000 cells per cm2 ('HIGH(×2)'), and subsequently analyzed for their propensity to proliferate. They were also subjected to morphometric analyses comparing cell sizes, coefficient of variance, as well as cell circularity when each culture became confluent. At the two lower densities, proliferation rates were higher than cells seeded at higher densities, though not statistically significant. However, corneal endothelial cells seeded at lower densities were significantly larger in size, heterogeneous in shape and less circular (fibroblastic-like), and remained hypertrophic after one month in culture. Comparatively, cells seeded at higher densities were significantly homogeneous, compact and circular at confluence. Potentially, at an optimal seeding density of 10,000 cells per cm2, it is possible to obtain between 10 million to 25 million cells at the third passage. More importantly, these expanded human corneal endothelial cells retained their unique cellular morphology. Our results demonstrated a density dependency in the culture of primary human corneal endothelial cells. Sub-optimal seeding density results in a decrease in cell saturation density, as well as a loss in their proliferative potential. As such, we propose a seeding density of not less than 10,000 cells per cm2 for regular passage of primary human corneal endothelial cells.

Corneal tissue water content mapping with THz imaging: preliminary clinical results (Conference Presentation)

NASA Astrophysics Data System (ADS)

Sung, Shijun; Bajwa, Neha; Deng, Sophie X.; Taylor, Zachary; Grundfest, Warren

2016-03-01

Well-regulated corneal water content is critical for ocular health and function and can be adversely affected by a number of diseases and injuries. Current clinical practice limits detection of unhealthy corneal water content levels to central corneal thickness measurements performed by ultrasound or optical coherence tomography. Trends revealing increasing or decreasing corneal thickness are fair indicators of corneal water content by individual measurements are highly inaccurate due to the poorly understood relationship between corneal thickness and natural physiologic variation. Recently the utility of THz imaging to accuarately measure corneal water content has been explored on with rabbit models. Preliminary experiments revealed that contact with dielectric windows confounded imaging data and made it nearly impossible to deconvolve thickness variations due to contact from thickness variations due to water content variation. A follow up study with a new optical design allowed the acquisition of rabbit data and the results suggest that the observed, time varying contrast was due entirely to the water dynamics of the cornea. This paper presents the first ever in vivo images of human cornea. Five volunteers with healthy cornea were recruited and their eyes were imaged three times over the course of a few minutes with our novel imaging system. Noticeable changes in corneal reflectivity were observed and attributed to the drying of the tear film. The results suggest that clinically compatible, non-contact corneal imaging is feasible and indicate that signal acquired from non-contact imaging of the cornea is a complicated coupling of stromal water content and tear film.

Innate Immune Regulation of Serratia marcescens–Induced Corneal Inflammation and Infection

PubMed Central

Zhou, Rong; Zhang, Rui; Sun, Yan; Platt, Sean; Szczotka-Flynn, Loretta; Pearlman, Eric

2012-01-01

Purpose. Serratia marcescens is frequently isolated from lenses of patients with contact lens-associated corneal infiltrates. In the current study, we examined the role of toll-like receptors (TLRs) and interleukin-1 receptor type 1 (IL-1R1) in S. marcescens–induced corneal inflammation and infection. Methods. The central corneal epithelium of C57BL/6 and gene knockout mice was abraded, and 1 × 107 S. marcescens were added in the presence of a silicone hydrogel contact lens, and we examined corneal inflammation by confocal microscopy and neutrophil enumeration. Viable bacteria were quantified by colony-forming units (CFU). Results. S. marcescens induced neutrophil recruitment to the corneal stroma, and increased corneal thickness and haze in C57BL/6 mice. Conversely, CFU was significantly lower by 48 hours post infection. In contrast, MyD88−/−, IL-1R−/−, TLR4−/−, and TLR4/5−/− corneas infected with S. marcescens had significantly increased CFU, indicating impaired clearance. However, there was no significant difference in CFU among C57BL/6, TIRAP−/−, and TRIF−/− mice. Tobramycin-killed S. marcescens induced corneal inflammation in C57BL/6 mice, which was impaired significantly in MD-2−/− mice and in C57BL/6 mice pretreated topically with the MD-2 antagonist eritoran tetrasodium. Conclusions. S. marcescens induces corneal inflammation by activation of TLR4/MD-2/MyD88 and the IL-1R1/MyD88 pathways, which are potential therapeutic targets for inhibition of S. marcescens-induced corneal inflammation. PMID:23033384

Regulation of corneal stroma extracellular matrix assembly.

PubMed

Chen, Shoujun; Mienaltowski, Michael J; Birk, David E

2015-04-01

The transparent cornea is the major refractive element of the eye. A finely controlled assembly of the stromal extracellular matrix is critical to corneal function, as well as in establishing the appropriate mechanical stability required to maintain corneal shape and curvature. In the stroma, homogeneous, small diameter collagen fibrils, regularly packed with a highly ordered hierarchical organization, are essential for function. This review focuses on corneal stroma assembly and the regulation of collagen fibrillogenesis. Corneal collagen fibrillogenesis involves multiple molecules interacting in sequential steps, as well as interactions between keratocytes and stroma matrix components. The stroma has the highest collagen V:I ratio in the body. Collagen V regulates the nucleation of protofibril assembly, thus controlling the number of fibrils and assembly of smaller diameter fibrils in the stroma. The corneal stroma is also enriched in small leucine-rich proteoglycans (SLRPs) that cooperate in a temporal and spatial manner to regulate linear and lateral collagen fibril growth. In addition, the fibril-associated collagens (FACITs) such as collagen XII and collagen XIV have roles in the regulation of fibril packing and inter-lamellar interactions. A communicating keratocyte network contributes to the overall and long-range regulation of stromal extracellular matrix assembly, by creating micro-domains where the sequential steps in stromal matrix assembly are controlled. Keratocytes control the synthesis of extracellular matrix components, which interact with the keratocytes dynamically to coordinate the regulatory steps into a cohesive process. Mutations or deficiencies in stromal regulatory molecules result in altered interactions and deficiencies in both transparency and refraction, leading to corneal stroma pathobiology such as stromal dystrophies, cornea plana and keratoconus. Copyright © 2014 Elsevier Ltd. All rights reserved.

Short-term corneal changes with gas-permeable contact lens wear in keratoconus subjects: a comparison of two fitting approaches.

PubMed

Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; Flores-Rodríguez, Patricia; González-Méijome, Jose-Manuel

2015-01-01

To evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches. Thirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-touch or three-point-touch fitting approach. The lens' back optic zone radius (BOZR) was 0.4mm and 0.1mm flatter than the first definite apical clearance lens, respectively. Differences between the baseline and post-CL wear for steepest, flattest and average corneal power (ACP) readings, central corneal astigmatism (CCA), maximum tangential curvature (KTag), anterior corneal surface asphericity, anterior corneal surface HOA and thinnest corneal thickness measured with Pentacam were compared. A statistically significant flattening was found over time on the flattest and steepest simulated keratometry and ACP in apical-touch group (all p<0.01). A statistically significant reduction in KTag was found in both groups after contact lens wear (all p<0.05). Significant reduction was found over time in CCA (p=0.001) and anterior corneal asphericity in both groups (p<0.001). Thickness at the thinnest corneal point increased significantly after CL wear (p<0.0001). Coma-like and total HOA root mean square (RMS) error were significantly reduced following CL wearing in both fitting approaches (all p<0.05). Short-term rigid gas-permeable CL wear flattens the anterior cornea, increases the thinnest corneal thickness and reduces anterior surface HOA in keratoconus subjects. Apical-touch was associated with greater corneal flattening in comparison to three-point-touch lens wear. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Comparative analysis of corneal morphological changes after transversal and torsional phacoemulsification through 2.2 mm corneal incision.

PubMed

Assaf, Ahmed; Roshdy, Maged Maher

2013-01-01

This paper compares and evaluates the corneal morphological changes occurring after cataract surgery through a 2.2 mm corneal incision. We use two platforms for comparison and evaluation, transversal and torsional phacoemulsification. This study includes 139 consecutive cataractous eyes (nuclear color 2-4, according to the Lens Opacities Classification System III [LOCSIII]) of 82 patients undergoing cataract surgery through a 2.2 mm corneal incision. Two different phacoemulsification platforms were used and assigned randomly: we used the WhiteStar Signature(®) system with the Ellips™ FX transversal continuous ultrasound (US) mode for group I (mean age: 65.33 ± 6.97 years), and we used the Infiniti(®) system with the OZil(®) Intelligent Phaco (IP) torsional US mode for group II (mean age: 64.02 ± 7.55 years). The corneal endothelium and pachymetry were evaluated preoperatively and at 1 month postoperatively. Incision size changes were also evaluated. All surgeries were uneventful. Before intraocular lens implantation, the mean incision size was 2.24 ± 0.06 mm in both groups (P = 0.75). In terms of corneal endothelial cell density, neither preoperative (I vs II: 2304.1 ± 122.5 cell/mm(2) vs 2315.6 ± 83.1 cell/mm(2), P = 0.80) nor postoperative (I vs II: 2264.1 ± 124.3 cell/mm(2) vs 2270.3 ± 89.9 cell/mm(2), P = 0.98) differences between the groups were statistically significant. The mean endothelial cell density loss was 1.7% ± 1.6% and 2.0% ± 1.4% in groups I and II, respectively. Furthermore, no significant differences between groups I and II were found preoperatively (P = 0.40) and postoperatively (P = 0.68) in central pachymetry. With surgery, the mean increase in central pachymetry was 28.1 ± 23.6 μm and 24.0 ± 24.0 μm in groups I and II, respectively (P = 0.1). Ellips™ FX transversal and OZil(®) IP torsional phacoemulsification modes are safe for performing cataract surgery, inducing minimal corneal thickness and endothelial changes.

Comparative analysis of corneal morphological changes after transversal and torsional phacoemulsification through 2.2 mm corneal incision

PubMed Central

Assaf, Ahmed; Roshdy, Maged Maher

2013-01-01

Purpose This paper compares and evaluates the corneal morphological changes occurring after cataract surgery through a 2.2 mm corneal incision. We use two platforms for comparison and evaluation, transversal and torsional phacoemulsification. Patients and methods This study includes 139 consecutive cataractous eyes (nuclear color 2–4, according to the Lens Opacities Classification System III [LOCSIII]) of 82 patients undergoing cataract surgery through a 2.2 mm corneal incision. Two different phacoemulsification platforms were used and assigned randomly: we used the WhiteStar Signature® system with the Ellips™ FX transversal continuous ultrasound (US) mode for group I (mean age: 65.33 ± 6.97 years), and we used the Infiniti® system with the OZil® Intelligent Phaco (IP) torsional US mode for group II (mean age: 64.02 ± 7.55 years). The corneal endothelium and pachymetry were evaluated preoperatively and at 1 month postoperatively. Incision size changes were also evaluated. Results All surgeries were uneventful. Before intraocular lens implantation, the mean incision size was 2.24 ± 0.06 mm in both groups (P = 0.75). In terms of corneal endothelial cell density, neither preoperative (I vs II: 2304.1 ± 122.5 cell/mm2 vs 2315.6 ± 83.1 cell/mm2, P = 0.80) nor postoperative (I vs II: 2264.1 ± 124.3 cell/mm2 vs 2270.3 ± 89.9 cell/mm2, P = 0.98) differences between the groups were statistically significant. The mean endothelial cell density loss was 1.7% ± 1.6% and 2.0% ± 1.4% in groups I and II, respectively. Furthermore, no significant differences between groups I and II were found preoperatively (P = 0.40) and postoperatively (P = 0.68) in central pachymetry. With surgery, the mean increase in central pachymetry was 28.1 ± 23.6 μm and 24.0 ± 24.0 μm in groups I and II, respectively (P = 0.1). Conclusion Ellips™ FX transversal and OZil® IP torsional phacoemulsification modes are safe for performing cataract surgery, inducing minimal corneal thickness and endothelial changes. PMID:23326184

A comparison of interocular differences in patients with pigment dispersion syndrome.

PubMed

Yip, Leonard W; Sothornwit, Nisa; Berkowitz, Jonathan; Mikelberg, Frederick S

2009-01-01

Pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) are characterized by loss of iris pigment because of reverse pupillary block. The loss of iris pigment is manifested as transillumination defects. Differences in ocular anatomy have been found between subjects with PDS and controls. Our study aims to see if differences in interocular anatomic features are also related to differences in the quantity of transillumination defects between eyes. This is an observational case series of 30 eyes of 15 subjects with PDS/PG in at least 1 eye. Patients underwent refraction, exophthalmometry, corneal and anterior chamber analysis by Pentacam, biometry, A-scan, ultrasound biomicroscopy, and anterior segment digital photography. The Pentacam mean central radii of the posterior corneal surface (cornea back Rm), vertical central radius of curvature of the posterior corneal surface (cornea back Rv), and keratometric power deviation (influence of the posterior surface of the cornea on refractive power) were statistically different between eyes with greater pigment loss and eyes with lesser pigment loss. Eyes with greater pigment loss had a larger back radius of corneal curvature and a correspondingly numerically smaller keratometric power deviation. Other measurements of ocular anatomy were not statistically significant. A flatter curvature of the posterior corneal surface of the eye is associated with increased pigment loss in PDS and PG. The authors postulate that this could result in a difference in the biomechanical properties of the cornea, increased deformation with blinking, and a pumping action resulting in the reverse pupil block of PDS.

Corneal Densitometry as a Tool to Measure Epithelial Ingrowth After Laser In Situ Keratomileusis.

PubMed

Adran, Daniel; Vaillancourt, Louis; Harissi-Dagher, Mona; Kruh, Jonathan N; Syed, Zeba A; Robinson, Steven; Melki, Samir

2017-04-01

This study evaluates the correlation between corneal densitometry and epithelial ingrowth (EI) after laser in situ keratomileusis (LASIK). Corneal densitometry of 3 patients who developed EI after LASIK was measured with the Oculus Pentacam. Corneal densitometry readings of each patient were obtained preoperatively and postoperatively after ingrowth was discovered. Densitometry was recorded at the central nest of opacity and at the leading edges of EI. For all patients, the most severe stages of EI observed on slit-lamp photographs correlated with the highest densitometry readings, with peak densitometry ranging from 73.3 to 95.1. These values were much higher than preoperative densitometry readings, which ranged from 21.8 to 27.2. In 2 cases, the Pentacam densitometry map revealed progression of EI toward the visual axis that was only faintly detectable or not detectable at all on the corresponding slit-lamp photographs. Corneal densitometry seems to be an objective measure of the severity and progression of EI after LASIK.

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.

Novel mutations of the carbohydrate sulfotransferase-6 (CHST6) gene causing macular corneal dystrophy in India.

PubMed

Sultana, Afia; Sridhar, Mittanamalli S; Jagannathan, Aparna; Balasubramanian, Dorairajan; Kannabiran, Chitra; Klintworth, Gordon K

2003-12-22

Macular corneal dystrophy (MCD) is an autosomal recessive disorder characterized by progressive central haze, confluent punctate opacities and abnormal deposits in the cornea. It is caused by mutations in the carbohydrate sulfotransferase-6 (CHST6) gene, encoding corneal N-acetyl glucosamine-6-O-sulfotransferase (C-GlcNAc-6-ST). We screened the CHST6 gene for mutations in Indian families with MCD, in order to determine the range of pathogenic mutations. Genomic DNA was isolated from peripheral blood leukocytes of patients with MCD and normal controls. The coding regions of the CHST6 gene were amplified using three pairs of primers and amplified products were directly sequenced. We identified 22 (5 nonsense, 5 frameshift, 2 insertion, and 10 missense) mutations in 36 patients from 31 families with MCD, supporting the conclusion that loss of function of this gene is responsible for this corneal disease. Seventeen of these mutations are novel. These data highlight the allelic heterogeneity of macular corneal dystrophy in Indian patients.

Assessment of Corneal and Tear Film Parameters in Rheumatoid Arthritis Patients Using Anterior Segment Spectral Domain Optical Coherence Tomography.

PubMed

El-Fayoumi, Dina; Youssef, Maha Mohamed; Khafagy, Mohamed Mahmoud; Badr El Dine, Nashwa; Gaber, Wafaa

2018-01-01

To study the corneal changes in rheumatoid arthritis (RA) patients in vivo, using spectral domain anterior segment optical coherence tomography (AS-OCT). A case-control study was done on 43 RA patients and 40 controls. The disease activity score (DAS28-ESR) was calculated and all participants had lower tear meniscus, corneal thickness, and epithelial thickness evaluation using AS-OCT. The lower tear meniscus height (LTMH) and the lower tear meniscus area (LTMA) were significantly lower in the RA patients than in controls (p < 0.001). RA patients also had a significantly thinner central corneal thickness (p = 0.02) and their epithelium was found to be thinner in the superotemporal peripheral sector. The LTMH and LTMA are significantly reduced in RA patients, despite the absence of clinical diagnosis of dry eye. RA patients have thinner corneal thickness and epithelial thickness than controls, which did not correlate with either disease duration or activity.

Treatment of alkali-injured cornea by cyclosporine A-loaded electrospun nanofibers - An alternative mode of therapy.

PubMed

Cejkova, Jitka; Cejka, Cestmir; Trosan, Peter; Zajicova, Alena; Sykova, Eva; Holan, Vladimir

2016-06-01

In this study we tried to develop a new approach to suppress inflammation and neovascularization in the alkali-injured rabbit cornea. For this reason Cyclosporine A (CsA)-loaded electrospun nanofibers were transferred onto the ocular surface injured with alkali (0.25 N NaOH). Damaged corneas were divided into the following groups: untreated, treated with CsA eye drops, treated with nanofibers drug-free and treated with CsA-loaded nanofibers. Healthy rabbit corneas served as controls. Drug-free nanofibers and CsA-loaded nanofibers were transferred onto the damaged corneal surface immediately after the injury and sutured to conjunctiva. On day five after the injury the nanofibers were removed. The animals from all groups were sacrificed on day twelve after the injury. The extent of the inflammatory reaction and corneal healing were examined macroscopically, immunohistochemically and biochemically. The central corneal thickness was measured using an ultrasonic pachymeter. When compared with untreated injured corneas, injured corneas treated with drug-free nanofibers or injured corneas treated with CsA eye drops, the number of CD3-positive cells (T lymphocytes) and the production of pro-inflammatory cytokines were strongly reduced in corneas treated with CsA-loaded nanofibers, which was associated with the significantly decreased expression of matrix metalloproteinase 9, inducible nitric oxide synthase, vascular endothelial growth factor and active caspase-3. CsA-loaded nanofibers effectively suppressed corneal inflammation and corneal neovascularization. Central corneal thickness restored to levels before injury only in corneas treated with CsA-loaded nanofibers. Corneal transparency was highly restored in these corneas. It is suggested that the beneficial effect of CsA-loaded nanofibers was associated with the continuous release of CsA from nanofibers and continuous affection of damaged cornea by CsA. The suture of nanofibers to conjunctiva and the closed eyes contributed to beneficial corneal healing. This is in contrast to CsA eye drops, which are quickly washed from the ocular surface and the contact of CsA with the damaged cornea was limited. In conclusion, the approach with CsA-loaded nanofibers could represent an effective alternative mode of therapy for corneal chemical burns. Copyright © 2016 Elsevier Ltd. All rights reserved.

Topographic steep central islands following excimer laser photorefractive keratectomy

NASA Astrophysics Data System (ADS)

Krueger, Ronald R.; McDonnell, Peter J.

1994-06-01

The purpose of this study is to demonstrate that topographic irregularities in the form of central islands of higher refractive power can be seen following excimer laser refractive surgery. We reviewed the computerized corneal topographic maps of 35 patients undergoing excimer laser PRK for compound myopic astigmatism or anisometropia from 8/91 to 8/93 at the USC/Doheny Eye Institute. The topographic maps were generated by the Computed Anatomy Corneal Modeling System, and central islands were defined as topographic areas of steepening of at least 3 diopters and 3 mm in diameter. A grading system was developed based on the presence of central islands during the postoperative period. Visually significant topographic steep central islands may be seen in over 50% of patients at 1 month following excimer laser PRK, and persist at 3 months in up to 24% of patients without nitrogen gas blowing. Loss of best corrected visual acuity or ghosting is associated with island formation, and may prolong visual rehabilitation after excimer laser PRK.

Corneal biomechanical changes in diabetes mellitus and their influence on intraocular pressure measurements.

PubMed

Sahin, Afsun; Bayer, Atilla; Ozge, Gökhan; Mumcuoğlu, Tarkan

2009-10-01

To investigate possible corneal biomechanical changes in patients with diabetes mellitus and understand the influence of such changes on intraocular pressure measurements. The study group was composed of 120 eyes from 61 healthy control subjects and 81 eyes from 43 diabetic subjects. IOP was measured first with an ocular response analyzer (ORA) and subsequently with a Goldmann applanation tonometer (GAT). Central corneal thickness (CCT) was measured with an ultrasonic pachymeter attached to the ORA. Axial length (AL), anterior chamber depth (ACD), and keratometry readings were acquired with partial coherence laser interferometry during the same visit before all IOP and CCT determinations were made. Corneal hysteresis (CH) was found to be significantly lower in diabetic patients when compared with healthy control subjects (9.51 +/- 1.82 mm Hg vs. 10.41 +/- 1.66 mm Hg, P < 0.0001). There was no significant difference in terms of corneal resistance factor (CRF; P = 0.8). Mean CCT, GAT IOP, Goldmann-correlated IOP (IOPg), and corneal-compensated IOP (IOPcc) were significantly higher in diabetic patients than in healthy control subjects (P = 0.01 for CCT, P < 0.0001 for GAT IOP, IOPg, and IOPcc). Diabetes affects corneal biomechanics and results in lower CH values than those in healthy control subjects, which may cause clinically relevant high IOP measurements independent of CCT.

Self-organized centripetal movement of corneal epithelium in the absence of external cues

NASA Astrophysics Data System (ADS)

Lobo, Erwin P.; Delic, Naomi C.; Richardson, Alex; Raviraj, Vanisri; Halliday, Gary M.; di Girolamo, Nick; Myerscough, Mary R.; Lyons, J. Guy

2016-08-01

Maintaining the structure of the cornea is essential for high-quality vision. In adult mammals, corneal epithelial cells emanate from stem cells in the limbus, driven by an unknown mechanism towards the centre of the cornea as cohesive clonal groups. Here we use complementary mathematical and biological models to show that corneal epithelial cells can self-organize into a cohesive, centripetal growth pattern in the absence of external physiological cues. Three conditions are required: a circumferential location of stem cells, a limited number of cell divisions and mobility in response to population pressure. We have used these complementary models to provide explanations for the increased rate of centripetal migration caused by wounding and the potential for stem cell leakage to account for stable transplants derived from central corneal tissue, despite the predominantly limbal location of stem cells.

Corneal Epithelium Thickness Profile in 614 Normal Chinese Children Aged 7-15 Years Old.

PubMed

Ma, Yingyan; He, Xiangui; Zhu, Xiaofeng; Lu, Lina; Zhu, Jianfeng; Zou, Haidong

2016-03-23

The purpose of the study is to describe the values and distribution of corneal epithelium thickness (CET) in normal Chinese school-aged children, and to explore associated factors with CET. CET maps were measured by Fourier-domain optical coherence tomography (FD-OCT) in normal Chinese children aged 7 to 15 years old from two randomly selected schools in Shanghai, China. Children with normal intraocular pressure were further examined for cycloplegic autorefraction, corneal curvature radius (CCR) and axial length. Central (2-mm diameter area), para-central (2- to 5-mm diameter area), and peripheral (5- to 6-mm diameter area) CET in the superior, superotemporal, temporal, inferotemporal, inferior, inferonasal, nasal, superonasal cornea; minimum, maximum, range, and standard deviation of CET within the 5-mm diameter area were recorded. The CET was thinner in the superior than in the inferior and was thinner in the temporal than in the nasal. The maximum CET was located in the inferior zone, and the minimum CET was in the superior zone. A thicker central CET was associated with male gender (p = 0.009) and older age (p = 0.037) but not with CCR (p = 0.061), axial length (p = 0.253), or refraction (p = 0.351) in the multiple regression analyses. CCR, age, and gender were correlated with para-central and peripheral CET.

Central corneal thickness in children.

PubMed

Bradfield, Yasmin S; Melia, B Michele; Repka, Michael X; Kaminski, Brett M; Davitt, Bradley V; Johnson, David A; Kraker, Raymond T; Manny, Ruth E; Matta, Noelle S; Weise, Katherine K; Schloff, Susan

2011-09-01

To determine the central corneal thickness (CCT) in healthy white, African American, and Hispanic children from birth to 17 years of age and to determine whether CCT varies by age, race, or ethnicity. Prospective observational multicenter study. Central corneal thickness was measured with a handheld contact pachymeter. A total of 2079 children were included in the study, with ages ranging from birth to 17 years. Included were 807 whites, 494 Hispanics, and 474 African Americans, in addition to Asian, unknown race, and mixed-race individuals. African American children had thinner corneas on average than that of both white and Hispanic children (P < .001 for both) by approximately 20 μm. Thicker median CCT was observed with each successive year of age from age 1 to 11 years, with year-to-year differences steadily decreasing and reaching a plateau after age 11 at 573 μm in white and Hispanic children and 551 μm in African American children. For every 100 μm of thicker CCT measured, the intraocular pressure was 1.5 mm Hg higher on average (P < .001). For every diopter of increased myopic refractive error, CCT was 1 μm thinner on average (P < .001). Median CCT increases with age from 1 to 11 years, with the greatest increase present in the youngest age groups. African American children on average have thinner central corneas than white and Hispanic children, whereas white and Hispanic children demonstrate similar CCT.

Femtosecond laser-assisted deep anterior lamellar keratoplasty with big-bubble technique for keratoconus.

PubMed

Lu, Yan; Chen, Xiangfei; Yang, Liping; Xue, Chunyan; Huang, Zhenping

2016-09-01

The purpose of this study was to evaluate the clinical results after deep anterior lamellar keratoplasty (DALK) assisted by the femtosecond laser with big-bubble technique for keratoconus. A case series of 22 eyes in 19 patients with keratoconus was enrolled in the study. The 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany) was used to create a vertical side cut on donor and recipient corneas. Intraoperative and postoperative complications, uncorrected visual acuity, best-corrected visual acuity, corneal curvature, and central corneal thickness were evaluated in all patients. Big-bubble and naked Descemet's membrane (DM) were successfully achieved in twenty eyes (90.9%). Intraoperative macroperforation of DM occurred in two cases and converted to full-thickness keratoplasty. The mean follow-up time was 18.8 ± 5.3 months. The best-corrected visual acuity was increased from 0.3 to 1.0, mean corneal curvature was 43.0 ± 2.3D, and mean central corneal thickness was 508.9 ± 60.1 μm (range, from 430 to 600 μm) postoperatively. Our results indicate that femtosecond laser-assisted DALK with big-bubble technique is an accurate, safe, and effective method to treat the patients with keratoconus.

Validity of autorefractor based screening method for irregular astigmatism compared to the corneal topography- a cross sectional study.

PubMed

Galindo-Ferreiro, Alicia; De Miguel-Gutierrez, Julita; González-Sagrado, Manuel; Galvez-Ruiz, Alberto; Khandekar, Rajiv; Schellini, Silvana; Galindo-Alonso, Julio

2017-01-01

To present a method of screening for irregular astigmatism with an autorefractor and its determinants compared to corneal topography. This cross-sectional validity study was conducted in 2013 at an eye hospital in Spain. A tabletop autorefractor (test 1) was used to measure the refractive status of the anterior surface of the cornea at two corneal meridians of each eye. Then corneal topography (test 2) and Bogan's classification was used to group eyes into those with regular or no astigmatism (GRI) and irregular astigmatism (GRII). Test 1 provided a single absolute value for the greatest cylinder difference (Vr). The receiver operating characteristic (ROC) were plotted for the Vr values measured by test 1 for GRI and GRII eyes. On the basis a Vr value of 1.25 D as cut off, sensitivity, specificity were also calculated. The study sample was comprised of 260 eyes (135 patients). The prevalence of irregular astigmatism was 42% [95% confidence interval (CI): 36, 48]. Based on test 2, there were 151 eyes in GRI and 109 eyes in GRII. The median Vr was 0.75 D (25% quartile, 0.5 D) for GRI and 1.75 D (25% quartile, 1.25 D) for GRII. The area under curve was 0.171 for GRI and 0.83 for GRII. The sensitivity of test I was 78.1% and the specificity was 76.1%. A conventional autorefractor can be effective as a first level screening method to detect irregular corneal astigmatism in places where corneal topography facilities are not available.

The Relation of Ocular Surface Irregularity and Visual Disturbance in Early Stage Acanthamoeba Keratitis.

PubMed

Matsumoto, Yukihiro; Kodama, Asako; Goto, Eiki; Kawakita, Tetsuya; Dogru, Murat; Tsubota, Kazuo

2017-01-01

To evaluate the relation between ocular surface irregularity and visual disturbance in early stage Acanthamoeba keratitis (AK). Fifteen patients with culture-proven AK underwent routine ophthalmic examinations, including best-corrected visual acuity (BCVA) measurement, slitlamp biomicroscope examination, and corneal fluorescein dye staining test, in both the eyes. We also evaluated the corneal sensitivity with Cochet-Bonnet esthesiometer, tear functions by Schirmer's test, and ocular surface irregularity by corneal topography and compared the results with the contralateral healthy eyes in this study. The mean logarithm of the minimum angle of resolution BCVA (0.71±0.77) was significantly lower in the eyes with AK (P=0.002). Epithelial disorders were present in all eyes, and radial keratoneuritis in 14 eyes (93.3%). The mean corneal sensitivity (39.3±24.1 mm) was significantly lower in eyes with AK compared with the healthy eyes (P=0.005). The mean Schirmer's test value (22.5±12.0 mm) in eyes with AK was significantly higher compared with the healthy eyes (P=0.01). The ocular surface irregularity indices (the surface regularity index, 2.47±0.42; the surface asymmetry index, 3.24±1.31) were significantly higher in eyes with AK compared with contralateral healthy eyes (P<0.0001 and P<0.0001, respectively). The ocular surface disease in AK is associated with decrease in corneal sensitivity and increase in Schirmer's test value and ocular surface irregularity indices. The visual disturbance in AK may owe not only to corneal haze but also to ocular surface irregularity.

Influence of eye biometrics and corneal micro-structure on noncontact tonometry.

PubMed

Jesus, Danilo A; Majewska, Małgorzata; Krzyżanowska-Berkowska, Patrycja; Iskander, D Robert

2017-01-01

Tonometry is widely used as the main screening tool supporting glaucoma diagnosis. Still, its accuracy could be improved if full knowledge about the variation of the corneal biomechanical properties was available. In this study, Optical Coherence Tomography (OCT) speckle statistics are used to infer the organisation of the corneal micro-structure and hence, to analyse its influence on intraocular pressure (IOP) measurements. Fifty-six subjects were recruited for this prospective study. Macro and micro-structural corneal parameters as well as subject age were considered. Macro-structural analysis included the parameters that are associated with the ocular anatomy, such as central corneal thickness (CCT), corneal radius, axial length, anterior chamber depth and white-to-white corneal diameter. Micro-structural parameters which included OCT speckle statistics were related to the internal organisation of the corneal tissue and its physiological changes during lifetime. The corneal speckle obtained from OCT was modelled with the Generalised Gamma (GG) distribution that is characterised with a scale parameter and two shape parameters. In macro-structure analysis, only CCT showed a statistically significant correlation with IOP (R2 = 0.25, p<0.001). The scale parameter and the ratio of the shape parameters of GG distribution showed statistically significant correlation with IOP (R2 = 0.19, p<0.001 and R2 = 0.17, p<0.001, respectively). For the studied group, a weak, although significant correlation was found between age and IOP (R2 = 0.053, p = 0.04). Forward stepwise regression showed that CCT and the scale parameter of the Generalised Gamma distribution can be combined in a regression model (R2 = 0.39, p<0.001) to study the role of the corneal structure on IOP. We show, for the first time, that corneal micro-structure influences the IOP measurements obtained from noncontact tonometry. OCT speckle statistics can be employed to learn about the corneal micro-structure and hence, to further calibrate the IOP measurements.

Application of Corvis ST to evaluate the effect of femtosecond laser-assisted cataract surgery on corneal biomechanics.

PubMed

Wei, Yinjuan; Xu, Lingxiao; Song, Hui

2017-08-01

The aim of the present study was to evaluate the effects of femtosecond laser-assisted cataract surgery (FLACS) and phacoemulsification on corneal biomechanics using corneal visualization Scheimpflug technology. The medical records of 50 eyes from 50 patients who received phacoemulsification and intraocular lens implantation because of age-related factors between June 2014 and September 2014 were retrospectively analyzed. FLACS was used in 12 eyes (FLACS group), and conventional phacoemulsification in 38 eyes (PHACO group). The evaluation of corneal biomechanical parameters included the first/second applanation time (A-time1/A-time2), the first/second applanation length (A-length1/A-length2), corneal velocity during the first/second applanation moment (Vin/Vout), highest concavity time, highest concavity-radius (HC-radius), peak distance (PD), deformation amplitude (DA), central corneal thickness (CCT), and intraocular pressure (IOP). The differences in A-length1/A-length2, IOP, CCT, PD, and DA were significant in the PHACO group between those before, 1 week after, and 1 month after surgery. No significant differences in corneal biomechanical parameters were found between those at 1 month after surgery and before surgery. There were significant differences in IOP and CCT in the FLACS group between those before, 1 week after, and 1 month after surgery. There were no significant differences in the other corneal biomechanical parameters. No significant differences were found in corneal biomechanical parameters between those 1 month after surgery and before surgery. There were significant differences in A-length1/A-length2, CCT, PD, and DA between the two groups at 1 week after surgery. There were no significant differences in corneal biomechanical parameters between the two groups at 1 month after surgery. In conclusion, the effect of FLACS on corneal biomechanics is smaller than that of phacoemulsification. The corneal biomechanical parameters are restored to preoperative levels with the healing of the incision, and the reduction of swelling of the tissue near the incision.

Influence of eye biometrics and corneal micro-structure on noncontact tonometry

PubMed Central

Majewska, Małgorzata; Krzyżanowska-Berkowska, Patrycja; Iskander, D. Robert

2017-01-01

Purpose Tonometry is widely used as the main screening tool supporting glaucoma diagnosis. Still, its accuracy could be improved if full knowledge about the variation of the corneal biomechanical properties was available. In this study, Optical Coherence Tomography (OCT) speckle statistics are used to infer the organisation of the corneal micro-structure and hence, to analyse its influence on intraocular pressure (IOP) measurements. Methods Fifty-six subjects were recruited for this prospective study. Macro and micro-structural corneal parameters as well as subject age were considered. Macro-structural analysis included the parameters that are associated with the ocular anatomy, such as central corneal thickness (CCT), corneal radius, axial length, anterior chamber depth and white-to-white corneal diameter. Micro-structural parameters which included OCT speckle statistics were related to the internal organisation of the corneal tissue and its physiological changes during lifetime. The corneal speckle obtained from OCT was modelled with the Generalised Gamma (GG) distribution that is characterised with a scale parameter and two shape parameters. Results In macro-structure analysis, only CCT showed a statistically significant correlation with IOP (R2 = 0.25, p<0.001). The scale parameter and the ratio of the shape parameters of GG distribution showed statistically significant correlation with IOP (R2 = 0.19, p<0.001 and R2 = 0.17, p<0.001, respectively). For the studied group, a weak, although significant correlation was found between age and IOP (R2 = 0.053, p = 0.04). Forward stepwise regression showed that CCT and the scale parameter of the Generalised Gamma distribution can be combined in a regression model (R2 = 0.39, p<0.001) to study the role of the corneal structure on IOP. Conclusions We show, for the first time, that corneal micro-structure influences the IOP measurements obtained from noncontact tonometry. OCT speckle statistics can be employed to learn about the corneal micro-structure and hence, to further calibrate the IOP measurements. PMID:28472178

Fusarium dimerum Species Complex (Fusarium penzigii) Keratitis After Corneal Trauma.

PubMed

do Carmo, Anália; Costa, Esmeralda; Marques, Marco; Quadrado, Maria João; Tomé, Rui

2016-12-01

We report a case of a keratitis associated with a Fusarium penzigii-a Fusarium dimerum species complex (FDSC)-in a 81-year-old woman after a corneal trauma with a tree branch. At patient admittance, slit lamp biomicroscopy revealed an exuberant chemosis, an inferior corneal ulcer with an associated inflammatory infiltrate, a central corneal abscess, bullous keratopathy and posterior synechiae. Corneal scrapes were obtained for identification of bacteria and fungi, and the patient started antibiotic treatment on empirical basis. Few days later, the situation worsened with the development of hypopyon. By that time, Fusarium was identified in cultures obtained from corneal scrapes and the patient started topical amphotericin B 0.15 %. Upon the morphological identification of the Fusarium as a FDSC, and since there was no clinical improvement, the treatment with amphotericin B was suspended and the patient started voriconazole 10 mg/ml, eye drops, hourly and voriconazole 200 mg iv, every 12 h for 1 month. The hypopyon resolved and the inflammatory infiltrate improved, but the abscess persisted at the last follow-up visit. The molecular identification revealed that the FDSC was a F. penzigii.

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.

Changes in rabbit corneal innervation induced by the topical application of benzalkonium chloride.

PubMed

Chen, Wensheng; Zhang, Zhenhao; Hu, Jiaoyue; Xie, Hui; Pan, Juxin; Dong, Nuo; Liu, Zuguo

2013-12-01

To investigate the effect of benzalkonium chloride (BAK) on corneal nerves. Fifty-four adult New Zealand Albino rabbits were randomly divided into 3 groups. BAK at concentrations of 0.005%, 0.01%, or 0.02% was applied once daily to 1 eye of each rabbit for 9 days. The contralateral untreated eyes were used as controls. Corneal mechanical sensitivity, aqueous tear production, tear break-up time (BUT), fluorescein, and Rose Bengal staining scores were compared with those of control values on days 3, 6, and 9. Corneal whole mounts were immunostained with a specific antitubulin βIII antibody to label nerve fibers. Epithelial superficial nerve terminal, subbasal, and stromal nerve fiber densities were quantified. The structure of the central cornea was examined by means of in vivo confocal microscopy on day 9. The topical application of BAK resulted in lower corneal sensitivity and higher Rose Bengal staining scores on day 3, whereas there were no significant changes in the BUT, Schirmer, and corneal fluorescein scores. Decreased nerve densities in superficial and subbasal layers were observed in BAK-treated eyes on days 3 and 6, respectively. The eyes treated with 0.02% BAK exhibited significantly reduced Schirmer scores, BUT, and stromal nerve fiber density, and increased fluorescein staining scores on day 9. Corneal superficial epithelial cell size was significantly larger in all BAK-treated eyes compared with that in control eyes. The topical application of BAK can quickly cause corneal hypoesthesia without tear deficiency. Changes in corneal innervation significantly correlate with BAK-induced ocular surface changes.

Cellular Therapy With Human Autologous Adipose-Derived Adult Stem Cells for Advanced Keratoconus.

PubMed

Alió Del Barrio, Jorge L; El Zarif, Mona; de Miguel, María P; Azaar, Albert; Makdissy, Norman; Harb, Walid; El Achkar, Ibrahim; Arnalich-Montiel, Francisco; Alió, Jorge L

2017-08-01

The aim of this phase 1 study was to preliminarily evaluate the safety and efficacy of autologous adipose-derived adult stem cell (ADASC) implantation within the corneal stroma of patients with advanced keratoconus. Five consecutive patients were selected. Autologous ADASCs were obtained by elective liposuction. ADASCs (3 × 10) contained in 1 mL saline were injected into the corneal stroma through a femtosecond-assisted 9.5-mm diameter lamellar pocket under topical anesthesia. Patients were reviewed at 1 day, 1 week, 1, 3, and 6 months postoperatively. Visual function, manifest refraction, slit-lamp biomicroscopy, intraocular pressure, endothelial cell density, corneal topography, corneal optical coherence tomography, and corneal confocal biomicroscopy were recorded. No intraoperative or postoperative complications were recorded, with full corneal transparency recovery within 24 hours. Four patients completed the full follow-up. All patients improved their visual function (mean: 1 line of unaided and spectacle-corrected distance vision and 2 lines of rigid contact lens distance vision). Manifest refraction and topographic keratometry remained stable. Corneal optical coherence tomography showed a mean improvement of 16.5 μm in the central corneal thickness, and new collagen production was observed as patchy hyperreflective areas at the level of the stromal pocket. Confocal biomicroscopy confirmed the survival of the implanted stem cells at the surgical plane. Intraocular pressure and endothelial cell density remained stable. Cellular therapy of the human corneal stroma in vivo with autologous ADASCs appears to be safe. Stem cells survive in vivo with intrastromal new collagen production. Future studies with larger samples are required to confirm these preliminary results.

Management of corneal ectasia after LASIK with combined, same-day, topography-guided partial transepithelial PRK and collagen cross-linking: the athens protocol.

PubMed

Kanellopoulos, Anastasios John; Binder, Perry S

2011-05-01

To evaluate a series of patients with corneal ectasia after LASIK that underwent the Athens Protocol: combined topography-guided photorefractive keratectomy (PRK) to reduce or eliminate induced myopia and astigmatism followed by sequential, same-day ultraviolet A (UVA) corneal collagen cross-linking (CXL). Thirty-two consecutive corneal ectasia cases underwent transepithelial PRK (WaveLight ALLEGRETTO) immediately followed by CXL (3 mW/cm(2)) for 30 minutes using 0.1% topical riboflavin sodium phosphate. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, keratometry, central ultrasonic pachymetry, corneal tomography (Oculus Pentacam), and endothelial cell counts were analyzed. Mean follow-up was 27 months (range: 6 to 59 months). Twenty-seven of 32 eyes had an improvement in UDVA and CDVA of 20/45 or better (2.25 logMAR) at last follow-up. Four eyes showed some topographic improvement but no improvement in CDVA. One of the treated eyes required a subsequent penetrating keratoplasty. Corneal haze grade 2 was present in 2 eyes. Combined, same-day, topography-guided PRK and CXL appeared to offer tomographic stability, even after long-term follow-up. Only 2 of 32 eyes had corneal ectasia progression after the intervention. Seventeen of 32 eyes appeared to have improvement in UDVA and CDVA with follow-up >1.5 years. This technique may offer an alternative in the management of iatrogenic corneal ectasia. Copyright 2011, SLACK Incorporated.

Effect of Diabetes Mellitus and Metformin on Central Corneal Endothelial Cell Density in Eye Bank Eyes.

PubMed

Chocron, Isaac M; Rai, Dinesh K; Kwon, Ji-Won; Bernstein, Nicole; Hu, Jimmy; Heo, Moonseong; Lee, Jimmy K; Gore, Patrick K; McCartney, Mitchell D; Chuck, Roy S

2018-05-04

To determine whether metformin use and diabetes mellitus (DM) affect central corneal endothelial cell density (ECD) by examining an eye bank corneal donor database. The Lions Eye Institute corneal donor database, which consists of 38,318 corneal samples, was examined. Associations of ECD with metformin use and DM were tested by mixed effects linear models that account for correlations of outcomes between eyes within subjects adjusting for age, intraocular lens status, and glaucoma. Subjects (N = 17,056) with observed ECD counts for both eyes are included for analysis. Average donor age was 56.3 (SD = 15.0). ECD was not associated with metformin use (mean ± SE = 2592 ± 11.9 (N = 1014) versus nonuse [2592 ± 3.0 (N = 16,042), P = 0.302]; further analysis showed that ECD was not significantly associated with metformin use in patients with diabetes. However, metformin use was significantly associated with lower ECD among patients with glaucoma: [2658 ± 50.7 (N = 27) for use versus 2789 ± 19.0 (N = 164) for nonuse, P = 0.018]. The presence of DM was significantly associated with lower ECD 2581 ± 5.6 (N = 4766) for DM versus 2595 ± 3.4 (N = 12,290) for non-DM, P = 0.031). Lower ECD was associated with DM. Lower ECD was not associated with metformin use except in a subgroup of patients with glaucoma, in which subgroup analysis showed lower ECD. The differences in ECD observed were small and unlikely to affect the suitability for transplantation of donor corneas.

Delayed onset Mycobacterium intracellulare keratitis after laser in situ keratomileusis

PubMed Central

Ko, JaeSang; Kim, Se Kyung; Yong, Dong Eun; Kim, Tae-im; Kim, Eung Kweon

2017-01-01

Abstract Rationale: Infectious keratitis is a relatively uncommon but potentially sight-threatening complication of laser in situ keratomileusis (LASIK). Mycobacterial keratitis is usually regarded as late onset keratitis among post-LASIK keratitis. There has been no documented case of Mycobacterium intracellulare post-LASIK keratitis of a long-latent period. Patient concerns: A 36-year-old man was referred to our out-patient clinic, for persistent corneal epithelial defect with intrastromal infiltration. He had undergone uneventful bilateral LASIK procedure 4 years before. He complained decreased vision, accompanied by ocular pain, photophobia, and redness in his left eye for 7 months. Diagnosis: Lamellar keratectomy was taken using femtosecond laser. Bacterial culture with sequenced bacterial 16s ribosomal DNA confirmed the organism to be M intracellulare. Interventions: After 3 months of administration of topical clarithromycin, amikacin, and moxifloxacin, the corneal epithelial defect was resolved and the infiltration was much improved. However, newly developed diffuse haziness with surrounding granular infiltration in the central cornea was noted. Drug toxicity was suspected and topical moxifloxacin was discontinued, resulting in resolution of the diffuse haze with infiltration. Outcome: The patient was followed up regularly without medication thereafter and recurrence was not found for 7 years. Lessons: This case presents the first case of M intracellulare keratitis after LASIK. LASIK surgeons should aware that post-LASIK keratitis can develop long after the operation and careful suspicion of infectious disease with meticulous diagnostic test is needed. PMID:29390522

Delayed onset Mycobacterium intracellulare keratitis after laser in situ keratomileusis: A case report and literature review.

PubMed

Ko, JaeSang; Kim, Se Kyung; Yong, Dong Eun; Kim, Tae-Im; Kim, Eung Kweon

2017-12-01

Infectious keratitis is a relatively uncommon but potentially sight-threatening complication of laser in situ keratomileusis (LASIK). Mycobacterial keratitis is usually regarded as late onset keratitis among post-LASIK keratitis. There has been no documented case of Mycobacterium intracellulare post-LASIK keratitis of a long-latent period. A 36-year-old man was referred to our out-patient clinic, for persistent corneal epithelial defect with intrastromal infiltration. He had undergone uneventful bilateral LASIK procedure 4 years before. He complained decreased vision, accompanied by ocular pain, photophobia, and redness in his left eye for 7 months. Lamellar keratectomy was taken using femtosecond laser. Bacterial culture with sequenced bacterial 16s ribosomal DNA confirmed the organism to be M intracellulare. After 3 months of administration of topical clarithromycin, amikacin, and moxifloxacin, the corneal epithelial defect was resolved and the infiltration was much improved. However, newly developed diffuse haziness with surrounding granular infiltration in the central cornea was noted. Drug toxicity was suspected and topical moxifloxacin was discontinued, resulting in resolution of the diffuse haze with infiltration. The patient was followed up regularly without medication thereafter and recurrence was not found for 7 years. This case presents the first case of M intracellulare keratitis after LASIK. LASIK surgeons should aware that post-LASIK keratitis can develop long after the operation and careful suspicion of infectious disease with meticulous diagnostic test is needed. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

Quantified histopathology of the keratoconic cornea.

PubMed

Mathew, Jessica H; Goosey, John D; Bergmanson, Jan P G

2011-08-01

This study systematically investigated and quantified histopathological changes in a series of keratoconic (Kc) corneas using a physiologically formulated fixative to not further distort the already distorted diseased corneas. Twelve surgically removed Kc corneal buttons were immediately preserved and processed for light and transmission electron microscopy using an established corneal protocol. Measurements were taken from the central cone and peripheral regions of the host button. The sample size examined ranged in length from 390 to 2608 μm centrally and 439 to 2242 μm peripherally. The average corneal thickness was 437 μm centrally and 559 μm peripherally. Epithelial thickness varied centrally from 14 to 92 μm and peripherally from 30 to 91 μm. A marked thickening of the epithelial basement membrane was noted in 58% of corneas. Centrally, anterior limiting lamina (ALL) was thinned or lost over 60% of the area examined, whereas peripheral cornea was also affected but to a lesser extent. Histopathologically, posterior cornea remained undisturbed by the disease. Anteriorly in the stroma, an increased number of cells and tissue debris were encountered, and some of these cells were clearly not keratocytes. It is concluded that Kc pathology, at least initially, has a distinct anterior focus involving the epithelium, ALL, and anterior stroma. The epithelium had lost its cellular uniformity and was compromised by the loss or damage to the ALL. The activity of the hitherto unreported recruited stromal cells may be to break down and remove ALL and anterior stromal lamellae, leading to the overall thinning that accompanies this disease.

Regulation of corneal repair by particle-mediated gene transfer of opioid growth factor receptor complementary DNA.

PubMed

Zagon, Ian S; Sassani, Joseph W; Malefyt, Kristin J; McLaughlin, Patricia J

2006-11-01

To determine whether molecular manipulation of the opioid growth factor receptor (OGFr) alters corneal reepithelialization following central corneal abrasion in rats. The plasmid pcDNA3.1 + OGFr, carrying the rat OGFr complementary DNA in both the sense and antisense orientations, and empty vector (EV), were delivered by gene gun to the rat cornea. After 24 hours, corneas were abraded and reepithelialization was documented by fluorescein photography. Twenty-four hours after wounding, DNA synthesis (with bromodeoxyuridine) was examined. Eyes transfected with sense constructs of OGFr had corneal defects that were 24%, 52%, and 50% larger than the EV group at 16, 24, and 28 hours, respectively. Conversely, corneas transfected with antisense constructs of OGFr had corneal defects that were 56% and 48% smaller than the EV group at 16 and 24 hours, respectively. Bromodeoxyuridine labeling in the basal and suprabasal layers of the antisense group were increased 3.3- and 3.7-fold, respectively, in DNA synthesis from corresponding EV layers; DNA synthesis was comparable in the sense and EV groups. Excess OGFr delays reepithelialization, whereas attenuation of OGFr accelerates repair of the corneal surface. Clinical Relevance Inhibition of opioid growth factor action using gene therapy could be important in the treatment of corneal diseases such as nonhealing and recurrent erosions, diabetic keratopathy, and neurotrophic keratitis.

Can manipulation of orthokeratology lens parameters modify peripheral refraction?

PubMed

Kang, Pauline; Gifford, Paul; Swarbrick, Helen

2013-11-01

To investigate changes in peripheral refraction, corneal topography, and aberrations induced by changes in orthokeratology (OK) lens parameters in myopes. Subjects were fitted with standard OK lenses that were worn overnight for 2 weeks. Peripheral refraction, corneal topography, and corneal surface aberrations were measured at baseline and after 14 nights of OK lens wear. Subsequent to a 2-week washout period, subjects were refitted with another set of lenses where one eye was randomly assigned to wear an OK lens with a smaller optic zone diameter (OZD) and the other eye with a steeper peripheral tangent. Measurements were taken again at a second baseline and after 14 days of overnight wear of the second OK lens set. Standard OK lenses with a 6-mm OZD and 1/4 peripheral tangent caused significant changes in both peripheral refraction and corneal topography. Significant hyperopic shift occurred in the central visual field (VF) while a myopic shift was found at 35 degrees in the nasal VF. OK induced significant reductions in corneal power at all positions along the horizontal corneal chord except at 2.4 mm nasal where there was no significant change and at 2.8 mm nasal where there was an increase in corneal refractive power. A positive shift in spherical aberration was induced for all investigated lens designs except for the 1/2 tangent design when calculated over a 4-mm pupil. Reducing OZD and steepening the peripheral tangent did not cause significant changes in peripheral refraction or corneal topography profiles across the horizontal meridian. OK lenses caused significant changes in peripheral refraction, corneal topography, and corneal surface aberrations. Modifying OZD and peripheral tangent made no significant difference to the peripheral refraction or corneal topography profile. Attempting to customize refraction and topography changes through manipulation of OK lens parameters appears to be a difficult task.

Corneal thickness: measurement and implications.

PubMed

Ehlers, Niels; Hjortdal, Jesper

2004-03-01

The thickness of the cornea was reported in more than 100-year-old textbooks on physiological optics (Helmholtz, Gullstrand). Physiological interest was revived in the 1950s by David Maurice, and over the next 50 years, this 'simple' biological parameter has been studied extensively. Several techniques for its measurement have been described and physiological and clinical significance have been studied. In this review, the different methods and techniques of measurement are briefly presented (optical, ultrasound). While the corneal thickness of many animals are the same over a considerable part of the surface, in the human cornea anterior and posterior curvature are not concentric giving rise to a problem of definition. Based on this the precision and accuracy of determining the central corneal thickness are discussed. Changes in corneal thickness reflects changes in function of the boundary layers, in particular the endothelial barrier. The absolute value of thickness is of importance for the estimation of IOP but also in diagnosis of corneal and systemic disorders. Finally it is discussed to what extent the thickness is a biometric parameter of significance, e.g. in the progression of myopia or in the development of retinal detachment.

Comparative Evaluation of the Corneal and Anterior Chamber Parameters Derived From Scheimpflug Imaging in Arab and South Asian Normal Eyes.

PubMed

Prakash, Gaurav; Srivastava, Dhruv; Avadhani, Kavitha; Thirumalai, Sandeep M; Choudhuri, Sounak

2015-11-01

To evaluate the differences in the normal corneal and anterior segment Scheimpflug parameters in Arab and South Asian eyes. This hospital-based study was performed at a cornea and refractive surgery service in Abu Dhabi. A total of 600 consecutive normal candidates of South Asian (group 1, n = 300) and Arab (group 2, n = 300) origins underwent Scheimpflug imaging (Sirius; Costruzione Strumenti Oftalmici, Italy). One eye was randomly selected for evaluation. The age and sex distributions in both groups were comparable. The pachymetric variables were statistically higher in group 2 (group 2 vs. group 1, 544.3 ± 32.2 μm vs. 535.1 ± 31.4 μm for central corneal thickness, 541.0 ± 32.6 μm vs. 531.9 ± 31.5 μm for minimum corneal thickness, 571.7 ± 43.2 μm vs. 558.1 ± 42.3 μm for apical thickness, and 58.1 ± 4.2 vs. 57.3 ± 4.3 mm³ for the corneal volume; P < 0.05). The anterior chamber volume (group 2 vs. group 1: 166.4 ± 16.4 vs. 161.6 ± 20.5 mm³) and angle (group 2 vs. group 1: 44.6 ± 6.2 vs. 43.5 ± 5.8 degrees) were also higher for group 2 (P < 0.05). Central corneal curvature and apical corneal curvature (apex K) were higher in group 1 (P < 0.05) with comparable astigmatism. The flat keratometry (K), steep K, and apex K were 43.6 ± 2.2 diopters (D), 44.9 ± 1.8 D, and 45.7 ± 1.8 D for group 1, and 43.1 ± 2.2 D, 44.5 ± 2 D, and 45.2 ± 1.9 D for group 2. The effect size (Cohen d) for significant parameters ranged from 0.2 to 0.3. Normal eyes of Arab ethnicity tend to have statistically thicker and flatter corneas and less-crowded anterior segments than those of the South Asian counterparts. These epidemiological differences have a mild to moderate biological effect size (Cohen d), but they should be considered when evaluating these eyes for anterior segment or corneal procedures.

Partial Denervation of Subbasal Axons Persists Following Debridement Wounds to the Mouse Cornea

PubMed Central

Pajoohesh-Ganji, Ahdeah; Pal-Ghosh, Sonali; Tadvalkar, Gauri; Kyne, Briana M.; Saban, Daniel R.; Stepp, Mary Ann

2015-01-01

Although sensory reinnervation occurs after injury in the PNS, poor reinnervation in the elderly and those with diabetes often leads to pathology. Here we quantify subbasal axon density in the central and peripheral mouse cornea over time after three different types of injury. The mouse cornea is highly innervated with a dense array of subbasal nerves that form a spiral called the vortex at the corneal center or apex; these nerves are readily detected within flat mounted corneas. After anesthesia, corneal epithelial cells were removed using either a dulled blade or a rotating burr within an area demarcated centrally with a 1.5 mm trephine. A third wound type, superficial trephination, involved demarcating the area with the 1.5 mm trephine but not removing cells. By 7d after superficial trephination, subbasal axon density returns to control levels; by 28d the vortex reforms. Although axon density is similar to control 14d after dulled blade and rotating burr wounding, defects in axon morphology at the corneal apex remain. After 14d, axons retract from the center leaving the subbasal axon density reduced by 37.2% and 36.8% at 28d after dulled blade and rotating burr wounding, respectively, compared to control. Assessment of inflammation using flow cytometry shows that persistent inflammation is not a factor in the incomplete reinnervation. Expression of mRNAs encoding 22 regeneration associated genes (RAGs) involved in axon targeting assessed by QPCR reveals that netrin-1 and ephrin signaling are altered after wounding. Subpopulations of corneal epithelial basal cells at the corneal apex stop expressing ki67 as early as 7d after injury and by 14d and 28d after wounding, many of these basal cells undergo apoptosis and die. While subbasal axons are restored to their normal density and morphology after superficial trephination, subbasal axon recovery is partial after debridement wounds. The increase in corneal epithelial basal cell apoptosis at the apex observed at 14d after corneal debridement may destabilize newly reinnervated subbasal axons and lead to their retraction towards the periphery. PMID:26280222

Partial denervation of sub-basal axons persists following debridement wounds to the mouse cornea.

PubMed

Pajoohesh-Ganji, Ahdeah; Pal-Ghosh, Sonali; Tadvalkar, Gauri; Kyne, Briana M; Saban, Daniel R; Stepp, Mary Ann

2015-11-01

Although sensory reinnervation occurs after injury in the peripheral nervous system, poor reinnervation in the elderly and those with diabetes often leads to pathology. Here we quantify sub-basal axon density in the central and peripheral mouse cornea over time after three different types of injury. The mouse cornea is highly innervated with a dense array of sub-basal nerves that form a spiral called the vortex at the corneal center or apex; these nerves are readily detected within flat mounted corneas. After anesthesia, corneal epithelial cells were removed using either a dulled blade or a rotating burr within an area demarcated centrally with a 1.5 mm trephine. A third wound type, superficial trephination, involved demarcating the area with the 1.5 mm trephine but not removing cells. By 7 days after superficial trephination, sub-basal axon density returns to control levels; by 28 days the vortex reforms. Although axon density is similar to control 14 days after dulled blade and rotating burr wounding, defects in axon morphology at the corneal apex remain. After 14 days, axons retract from the center leaving the sub-basal axon density reduced by 37.2 and 36.8% at 28 days after dulled blade and rotating burr wounding, respectively, compared with control. Assessment of inflammation using flow cytometry shows that persistent inflammation is not a factor in the incomplete reinnervation. Expression of mRNAs encoding 22 regeneration-associated genes involved in axon targeting assessed by QPCR reveals that netrin-1 and ephrin signaling are altered after wounding. Subpopulations of corneal epithelial basal cells at the corneal apex stop expressing ki67 as early as 7 days after injury and by 14 and 28 days after wounding, many of these basal cells undergo apoptosis and die. Although sub-basal axons are restored to their normal density and morphology after superficial trephination, sub-basal axon recovery is partial after debridement wounds. The increase in corneal epithelial basal cell apoptosis at the apex observed at 14 days after corneal debridement may destabilize newly reinnervated sub-basal axons and lead to their retraction toward the periphery.

Corneal power, thickness, and stiffness: results of a prospective randomized controlled trial of PRK and LASIK for myopia.

PubMed

Hjortdal, Jesper Ø; Møller-Pedersen, Torben; Ivarsen, Anders; Ehlers, Niels

2005-01-01

To compare the short-, medium-, and long-term changes in corneal optical power and corneal aberrations, central corneal thickness, and corneal "stiffness" assessed by pneumotonometry readings in patients having laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) for myopia. Department of Ophthalmology, Arhus University Hospital, Arhus, Denmark. One eye of each of 45 patients with myopia ranging from -6.00 to -8.00 diopters (D) (spherical equivalent spectacle refraction [SER]) was randomized to LASIK (n=25; mean SER -7.12 D +/- 0.57 [SD]) or PRK (n=20; mean SER -6.91 +/- 0.57 D). Data were collected prospectively before and 1, 3, 6, 12, and 36 months after surgery. Measurements included corneal topography (TMS-1, Tomey), corneal thickness (ultrasound pachymetry), and apparent intraocular pressure (IOP) (pneumotonometry). Retreatments were not performed during the first year, and retreated eyes were excluded from the 3-year follow-up. Changes in corneal power and aberrations, thickness, and apparent IOP were calculated in a pair-wise manner for 3 time periods: short term (preoperative to 1 month after surgery), medium term (1 to 12 months after surgery), and long term (1 to 3 years after surgery). In the short term, corneal power decreased equally in LASIK and PRK eyes. Spherical aberrations and coma-like aberrations increased equally, while corneal thickness decreased significantly less in LASIK eyes than in PRK eyes. The apparent IOP decreased more in LASIK eyes than in PRK eyes. In the medium term, corneal power increased significantly in both groups. Spherical aberrations decreased significantly in PRK eyes but not in LASIK eyes. From 1 to 12 months, corneal thickness increased more in PRK eyes than in LASIK eyes. During this period, the apparent IOP increased significantly in LASIK eyes. In the long term, corneal power and corneal aberrations did not change significantly in either group. Corneal thickness increased slightly but significantly in both groups. The apparent IOP increased significantly more in PRK eyes. Differences between LASIK and PRK related to time-dependent events affecting corneal shape and structural integrity were present. Peripheral changes in flap hydration in LASIK eyes and epithelial and/or stromal thickening in PRK eyes appeared to be the most important factors in optical power changes in the first year after treatment. The changes in apparent IOP suggest that some interlamellar healing occurred during the first year after LASIK. After LASIK and PRK, corneal bending stiffness seemed permanently decreased, although some restiffening may occur in PRK eyes in the long term.

Study of light scattering and transparency in human edematous corneas and application to corneal grafts

NASA Astrophysics Data System (ADS)

Marciano, Tal; Peyrot, Donald; Crotti, Caroline; Alahyane, Fatima; Kowalczuk, Laura; Plamann, Karsten

2011-07-01

The optical properties of the cornea have been a research subject of great interest for many years. Several early theories have been put forward to explain with more or less success the optical transparency of this tissue, but it was not until Maurice demonstrated in a very elegant way during the 50s that this optical transparency could be explained by the regular ultrastructure of the cornea. When becoming edematous, the cornea's ultrastructure is perturbed and the tissue becomes a strongly scattering medium. With the emergence of ophthalmologic surgery by ultrashort pulse lasers in recent years, a regain of interest in the subject of corneal transparency arose. However, relatively little and no recent data of transparency spectra measurements covering a large wavelength range is available in the literature. The purpose of this study is to provide quantitative values for light scattering and its relation to the degree of edema by measuring the spectrum of transmitted light through corneas presenting different degrees of edema. This paper focus on the comparison of laboratory measurements published earlier with a new simple method we propose We also for eye banks to quantitatively measure the degree of transparency of corneal grafts by measuring the modulation transfer function of a Siemens star viewed through a corneal graft. Indeed, there is no current method to determine the transparency of corneal graft but the subjectivity of the laboratory technician or the ophthalmic surgeon.

Topographic and biomechanical evaluation of cornea in patients with ichthyosis vulgaris.

PubMed

Kara, Necip; Yildirim, Yusuf; Demircan, Ali; Cankaya, Ilker; Kutlubay, Zekayi; Engin, Burhan; Serdaroglu, Server

2012-10-01

To compare the topographic and biomechanical properties of corneas in eyes of patients with ichthyosis vulgaris (IV) and eyes of healthy individuals. Thirty healthy individuals (control group) and 30 patients with IV (study group) were enrolled in this prospective study. Topographic measurements, including keratometry values, irregularity, and surface asymmetry index in the right eye of each participant were obtained using Scheimpflug camera with a Placido disc topographer (Sirius). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldman-related intraocular pressure (IOPg) were measured using the Reichert Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was also measured with ultrasonic pachymetry and the Sirius corneal topography system. Topographic parameters were not significantly different between both groups (p>0.05). Although mean CH was not significantly different between the groups, the CRF was significantly lower in patients with IV (p=0.249 and p=0.005, respectively). The CCT was significantly lower in patients with IV compared to healthy controls (p<0.001). The IOPg and IOPcc were significantly lower in the patients with ichthyosis than in healthy controls (p=0.001 and p=0.004, respectively). The study demonstrated that while the eyes of patients with IV had corneal topographic findings and corneal hysteresis similar to those of healthy controls, some of corneal biomechanical properties such CRF and CCT and IOP values such as IOPg and IOPcc were significantly lower in patients with IV. These results should be taken into account when planning a corneal refractive surgery and glaucoma screening for patients with IV. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Corneal Deformation Response and Ocular Geometry: A Noninvasive Diagnostic Strategy in Marfan Syndrome.

PubMed

Beene, Lauren C; Traboulsi, Elias I; Seven, Ibrahim; Ford, Matthew R; Sinha Roy, Abhijit; Butler, Robert S; Dupps, William J

2016-01-01

To evaluate corneal air-puff deformation responses and ocular geometry as predictors of Marfan syndrome. Prospective observational clinical study. Sixteen investigator-derived, 4 standard Ocular Response Analyzer (ORA), and geometric variables from corneal tomography and optical biometry using Oculus Pentacam and IOL Master were assessed for discriminative value in Marfan syndrome, measuring right eyes of 24 control and 13 Marfan syndrome subjects. Area under the receiver operating characteristic (AUROC) curve was assessed in univariate and multivariate analyses. Six investigator-derived ORA variables successfully discriminated Marfan syndrome. The best lone disease predictor was Concavity Min (Marfan syndrome 47.5 ± 20, control 69 ± 14, P = .003; AUROC = 0.80). Corneal hysteresis (CH) and corneal resistance factor (CRF) were decreased (Marfan syndrome CH 9.45 ± 1.62, control CH 11.24 ± 1.21, P = .01; Marfan syndrome CRF 9.77 ± 1.65, control CRF 11.03 ± 1.72, P = .01) and corneas were flatter in Marfan syndrome (Marfan syndrome Kmean 41.25 ± 2.09 diopter, control Kmean 42.70 ± 1.81 diopter, P = .046). No significant differences were observed in central corneal thickness, axial eye length, or intraocular pressure. A multivariate regression model incorporating corneal curvature and hysteresis loop area (HLA) provided the best predictive value for Marfan syndrome (AUROC = 0.85). This study describes novel biodynamic features of corneal deformation responses in Marfan syndrome, including increased deformation, decreased bending resistance, and decreased energy dissipation capacity. A predictive model incorporating HLA and corneal curvature shows greatest potential for noninvasive clinical diagnosis of Marfan syndrome. Copyright © 2016 Elsevier Inc. All rights reserved.

Corneal Deformation Response and Ocular Geometry: A Non-invasive Diagnostic Strategy in Marfan Syndrome

PubMed Central

Beene, Lauren C.; Traboulsi, Elias I.; Seven, Ibrahim; Ford, Matthew R.; Roy, Abhijit Sinha; Butler, Robert S.; Dupps, William J.

2015-01-01

Purpose To evaluate corneal air-puff deformation responses and ocular geometry as predictors of Marfan syndrome. Design Prospective observational clinical study Methods Sixteen investigator-derived, 4 standard Ocular Response Analyzer (ORA), and geometric variables from corneal tomography and optical biometry using Oculus Pentacam and IOL Master were assessed for discriminative value in Marfan syndrome, measuring right eyes of 24 control and 13 Marfan syndrome subjects. Area under the receiver operating characteristic (AUROC) curve was assessed in univariate and multivariate analyses Results Six investigator-derived ORA variables successfully discriminated Marfan syndrome. The best lone disease predictor was Concavity Min (Marfan syndrome 47.5 ± 20, control 69 ± 14, p = 0.003; AUROC = 0.80). Corneal hysteresis and corneal resistance factor were decreased (Marfan syndrome CH 9.45 ± 1.62, control CH 11.24 ± 1.21, p = 0.01; Marfan syndrome CRF 9.77 ± 1.65, control CRF 11.03 ± 1.72, p = 0.01) and corneas were flatter in Marfan syndrome (Marfan syndrome Kmean 41.25 ± 2.09 D, control Kmean 42.70 ± 1.81 D, p = 0.046). No significant differences were observed in central corneal thickness, axial eye length, or intraocular pressure. A multivariate regression model incorporating corneal curvature and hysteresis loop area (HLA) provided the best predictive value for Marfan syndrome (AUROC = 0.85). Conclusions This study describes novel biodynamic features of corneal deformation responses in Marfan syndrome, including increased deformation, decreased bending resistance, and decreased energy dissipation capacity. A predictive model incorporating HLA and corneal curvature shows greatest potential for non-invasive clinical diagnosis of Marfan syndrome. PMID:26432567

Topical Rosiglitazone Is an Effective Anti-Scarring Agent in the Cornea

PubMed Central

Huxlin, Krystel R.; Hindman, Holly B.; Jeon, Kye-Im; Bühren, Jens; MacRae, Scott; DeMagistris, Margaret; Ciufo, David; Sime, Patricia J.; Phipps, Richard P.

2013-01-01

Corneal scarring remains a major cause of blindness world-wide, with limited treatment options, all of which have side-effects. Here, we tested the hypothesis that topical application of Rosiglitazone, a Thiazolidinedione and ligand of peroxisome proliferator activated receptor gamma (PPARγ), can effectively block scar formation in a cat model of corneal damage. Adult cats underwent bilateral epithelial debridement followed by excimer laser ablation of the central corneal stroma to a depth of ∼160 µm as a means of experimentally inducing a reproducible wound. Eyes were then left untreated, or received 50 µl of either 10 µM Rosiglitazone in DMSO/Celluvisc, DMSO/Celluvisc vehicle or Celluvisc vehicle twice daily for 2 weeks. Cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and post-mortem immunohistochemistry for alpha smooth muscle actin (αSMA). Impacts of the wound and treatments on optical quality were assessed using wavefront sensing and optical coherence tomography at 2, 4, 8 and 12 weeks post-operatively. In parallel, cat corneal fibroblasts were cultured to assess the effects of Rosiglitazone on TGFβ-induced αSMA expression. Topical application of Rosiglitazone to cat eyes after injury decreased αSMA expression and haze, as well as the induction of lower-order and residual, higher-order wavefront aberrations compared to vehicle-treated eyes. Rosiglitazone also inhibited TGFβ-induced αSMA expression in cultured corneal fibroblasts. In conclusion, Rosiglitazone effectively controlled corneal fibrosis in vivo and in vitro, while restoring corneal thickness and optics. Its topical application may represent an effective, new avenue for the prevention of corneal scarring with distinct advantages for pathologically thin corneas. PMID:23940641

A new nanosecond UV laser at 355 nm: early results of corneal flap cutting in a rabbit model.

PubMed

Trost, Andrea; Schrödl, Falk; Strohmaier, Clemens; Bogner, Barbara; Runge, Christian; Kaser-Eichberger, Alexandra; Krefft, Karolina; Vogel, Alfred; Linz, Norbert; Freidank, Sebastian; Hilpert, Andrea; Zimmermann, Inge; Grabner, Günther; Reitsamer, Herbert A

2013-12-03

A new 355 nm UV laser was used for corneal flap cutting in an animal model and tested for clinical and morphologic alterations. Corneal flaps were created (Chinchilla Bastards; n = 25) with an UV nanosecond laser at 355 nm (150 kHz, pulse duration 850 ps, spot-size 1 μm, spot spacing 6 × 6 μm, side cut Δz 1 μm; cutting depth 130 μm) and pulse energies of 2.2 or 2.5 μJ, respectively. Following slit-lamp examination, animals were killed at 6, 12, and 24 hours after treatment. Corneas were prepared for histology (hematoxylin and eosin [HE], TUNEL-assay) and evaluated statistically, followed by ultrastructural investigations. Laser treatment was tolerated well, flap lift was easier at 2.5 μJ compared with 2.2 μJ. Standard HE at 24 hours revealed intact epithelium in the horizontal cut, with similar increase in corneal thickness at both energies. Irrespective of energy levels, TUNEL assay revealed comparable numbers of apoptotic cells in the horizontal and vertical cut at 6, 12, and 24 hours, becoming detectable in the horizontal cut as an acellular stromal band at 24 hours. Ultrastructural analysis revealed regular morphology in the epi- and endothelium, while in the stroma, disorganized collagen lamellae were detectable representing the horizontal cut, again irrespective of energy levels applied. This new UV laser revealed no epi- nor endothelial damage at energies feasible for corneal flap cutting. Observed corneal swelling was lower compared with existing UV laser studies, albeit total energy applied here was much higher. Observed loss of stromal keratinocytes is comparable with available laser systems. Therefore, this new laser is suitable for refractive surgery, awaiting its test in a chronic environment.

Early visual outcomes and optical quality after femtosecond laser small-incision lenticule extraction for myopia and myopic astigmatism correction of over -10 dioptres.

PubMed

Qin, Bing; Li, Meiyan; Chen, Xun; Sekundo, Walter; Zhou, Xingtao

2018-05-01

To investigate early visual and refractive outcomes, corneal stability and optical quality after femtosecond laser small-incision lenticule extraction (SMILE) for treating myopia and myopic astigmatism over -10 D. Thirty eyes (30 patients) with myopia and myopic astigmatism of over -10 D were treated with VisuMax ® femtosecond laser (version 3.0; Carl Zeiss Meditec AG, Jena, Germany). Six months postoperative safety, efficacy and predictability were evaluated. Corneal Scheimpflug topography was measured preoperatively, 1 day, 3 months and 6 months postoperatively. Wavefront aberrations were measured preoperatively, 3 months and 6 months postoperatively. Six months postoperatively, LogMAR uncorrected and corrected distance visual acuity (CDVA) were -0.013 ± 0.086 and -0.073 ± 0.069, respectively. 73% (97%) of eyes were within 0.5 (1) D of target refraction. No eyes lost CDVA, 43% (13 eyes) gained one line and 7% (two eyes) gained two lines. Mean corneal back curvature (KMB) and posterior central elevation (PCE) did not change significantly comparing preoperative and 6 months postoperative data (p = 0.91 and 0.77, respectively). Comparing 1 day with 6 months postoperative data, central corneal thickness (CCT), mean corneal front curvature (KMF), KMB and PCE did not change significantly (p = 0.27, 0.07, 0.52, 0.71, respectively). Total higher-order aberration (HOA), spherical aberration and coma increased significantly (p < 0.01) but trefoil remained stable (p = 0.49). Our results indicate that SMILE can correct myopia and myopic astigmatism of over -10 D predictably. No early ectasia was observed. Long-term changes in visual quality and corneal stability require further investigation. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

The effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis using the M-2 microkeratome

PubMed Central

Goussous, Iyad A; El-Agha, Mohamed-Sameh; Awadein, Ahmed; Hosny, Mohamed H; Ghaith, Alaa A; Khattab, Ahmed L

2017-01-01

Purpose The purpose of this study was to determine the effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis (LASIK). Methods This is a prospective controlled non-randomized, institutional study. Patients underwent either epi-LASIK with mitomycin (advanced surface ablation [ASA]), thin-flap LASIK (90 µm head), or thick-flap LASIK (130 µm head). In ASA, the Moria Epi-K hydroseparator was used. LASIK flaps were created using the Moria M-2 mechanical microkeratome. The corneal hysteresis (CH) and corneal resistance factor (CRF) were measured preoperatively and 3 months after surgery, using the Ocular Response Analyzer®. Results Ten patients (19 eyes) underwent ASA, 11 patients (16 eyes) underwent thin-flap LASIK, and 11 patients (16 eyes) underwent thick-flap LASIK. The mean preoperative CH was 10.47±0.88, 10.52±1.4, and 11.28±1.4 mmHg (p=0.043), respectively, decreasing after surgery by 1.75±1.02, 1.66±1.00, and 2.62±1.03 mmHg (p=0.017). The mean reduction of CH per micron of central corneal ablation was 0.031, 0.023, and 0.049 mmHg/µm (p=0.005). Mean preoperative CRF was 10.11±1.28, 10.34±1.87, and 10.62±1.76 mmHg (p=0.66), decreasing after surgery by 2.33±1.35, 2.77±1.03, and 2.92±1.10 mmHg (p=0.308). The mean reduction of CRF per micron of central corneal ablation was 0.039, 0.040, and 0.051 mmHg/µm (p=0.112). Conclusion Thick-flap LASIK caused a greater reduction of CH and CRF than thin-flap LASIK and ASA, although this was statistically significant only for CH. ASA and thin-flap LASIK were found to be biomechanically similar. PMID:29200820

The effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis using the M-2 microkeratome.

PubMed

Goussous, Iyad A; El-Agha, Mohamed-Sameh; Awadein, Ahmed; Hosny, Mohamed H; Ghaith, Alaa A; Khattab, Ahmed L

2017-01-01

The purpose of this study was to determine the effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis (LASIK). This is a prospective controlled non-randomized, institutional study. Patients underwent either epi-LASIK with mitomycin (advanced surface ablation [ASA]), thin-flap LASIK (90 µm head), or thick-flap LASIK (130 µm head). In ASA, the Moria Epi-K hydroseparator was used. LASIK flaps were created using the Moria M-2 mechanical microkeratome. The corneal hysteresis (CH) and corneal resistance factor (CRF) were measured preoperatively and 3 months after surgery, using the Ocular Response Analyzer ® . Ten patients (19 eyes) underwent ASA, 11 patients (16 eyes) underwent thin-flap LASIK, and 11 patients (16 eyes) underwent thick-flap LASIK. The mean preoperative CH was 10.47±0.88, 10.52±1.4, and 11.28±1.4 mmHg ( p =0.043), respectively, decreasing after surgery by 1.75±1.02, 1.66±1.00, and 2.62±1.03 mmHg ( p =0.017). The mean reduction of CH per micron of central corneal ablation was 0.031, 0.023, and 0.049 mmHg/µm ( p =0.005). Mean preoperative CRF was 10.11±1.28, 10.34±1.87, and 10.62±1.76 mmHg ( p =0.66), decreasing after surgery by 2.33±1.35, 2.77±1.03, and 2.92±1.10 mmHg ( p =0.308). The mean reduction of CRF per micron of central corneal ablation was 0.039, 0.040, and 0.051 mmHg/µm ( p =0.112). Thick-flap LASIK caused a greater reduction of CH and CRF than thin-flap LASIK and ASA, although this was statistically significant only for CH. ASA and thin-flap LASIK were found to be biomechanically similar.

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.

Evaluation of corneal pachymetry measurements by Galilei dual Scheimpflug camera.

PubMed

Karimian, Farid; Feizi, Sepehr; Faramarzi, Amir; Doozandeh, Azadeh; Yaseri, Mehdi

2012-01-01

We present an evaluation of corneal pachymetry measurements by Galilei dual Scheimpflug camera by comparing central corneal thickness measured by Galilei with Orbscan II and ultrasonic pachymetry. Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences and Negah Eye Center, Tehran, Iran. Central corneal thickness (CCT) was measured in 184 eyes of 92 healthy subjects using Galilei, Orbscan II, and ultrasonic (US) pachymetry. Considered as a benchmark, the measurements by US pachymetry were compared with those measured by the other 2 systems. Mean CCT was 544.4 ± 33.4 µm, 546.7 ± 37.9 µm, and 555.8 ± 29.6 µm as measured by US pachymetry, Orbscan II, and Galilei systems, respectively. The mean difference of readings measured by US pachymetry with those measured by Orbscan II (acoustic coefficient 0.96) and Galilei were 2.3 µm and 10.2 µm, respectively. In spite of this discrepancy, the Galilei system had better agreement with US pachymetry than Orbscan II and US pachymetry (correlation coefficient 0.947 vs 0.817) and considering 0.98 as acoustic coefficient for Galilei CCT reading, makes its measurements identical to ultrasound pachymetry. Galilei measurements of CCT are well correlated with ultrasound pachymetry in normal eyes. After considering an acoustic coefficient equal to 0.98 for Galilei, its measurements will become equal to ultrasound values.

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

Collagen organization in the chicken cornea and structural alterations in the retinopathy, globe enlarged (rge) phenotype--an X-ray diffraction study.

PubMed

Boote, Craig; Hayes, Sally; Jones, Simon; Quantock, Andrew J; Hocking, Paul M; Inglehearn, Chris F; Ali, Manir; Meek, Keith M

2008-01-01

An investigation into the collagenous structure of the mature avian cornea is presented. Wide-angle X-ray diffraction is employed to assess collagen organization in 9-month-old chicken corneas. The central 2-4mm corneal region features a preponderance of fibrils directed along the superior-inferior and nasal-temporal orthogonal meridians. More peripherally the orientation of fibrils alters in favor of a predominantly tangential arrangement. The chicken cornea appears to be circumscribed by an annulus of fibrils that extends into the limbus. The natural arrangement of collagen in the chicken cornea is discussed in relation to corneal shape and the mechanical requirements of avian corneal accommodation. Equivalent data are also presented from age-matched blind chickens affected with the retinopathy, globe enlarged (rge) mutation, characterized by an abnormally thick and flat cornea. The data indicate considerable realignment and redistribution of collagen lamellae in the peripheral rge cornea. In contrast to normal chickens, no obvious tangential collagen alignment was evident in the periphery of rge corneas. In mammals, the presence of a limbal fibril annulus is believed to be important in corneal shape preservation. We postulate that corneal flattening in rge chickens may be related to biomechanical changes brought about by an alteration in collagen arrangement at the corneal periphery.

Quality of vision after excimer laser phototherapeutic keratectomy with intraoperative mitomycin-C for Salzmann nodular degeneration.

PubMed

Reddy, Jagadesh C; Rapuano, Christopher J; Felipe, Anthony F; Nagra, Parveen K; Hammersmith, Kristin M

2014-07-01

To assess the effect of excimer laser phototherapeutic keratectomy (PTK) with intraoperative mitomycin-C (MMC) on the quality of vision in patients with Salzmann nodular degeneration (SND). Thirteen eyes of 12 patients were enrolled in the study between December 2010 and March 2012. Uncorrected and best-corrected Snellen distance visual acuities were measured at every visit. Contrast sensitivity and manifest refraction were measured preoperatively, at 1 month and at 3 months. Corneal topography, Galilei dual Scheimpflug imaging, VISX WaveScan, and ultrasound central corneal pachymetry were measured preoperatively and at 3 months after PTK procedure. Contrast sensitivity was statistically significantly better both at 1 month (P<0.01) and 3 months (P<0.01). Postoperatively, there was 46% increase in eyes with measurable corneal topography, 69% increase in Galilei dual Scheimpflug imaging, and a 77% increase in WaveScan measurements. The third-order (P<0.01) and total corneal higher-order aberrations (HOAs) (P=0.01) were significantly lower postoperatively compared with the preoperative corneal aberrations measured on Galilei dual Scheimpflug imaging. Significant improvement in contrast sensitivity and corneal HOAs was seen after PTK for SND. Phototherapeutic keratectomy with MMC can be considered as an effective procedure in the improvement of the quality of vision in patients with SND.

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.

Dry eyes and corneal sensation after laser in situ keratomileusis with femtosecond laser flap creation Effect of hinge position, hinge angle, and flap thickness.

PubMed

Mian, Shahzad I; Li, Amy Y; Dutta, Satavisha; Musch, David C; Shtein, Roni M

2009-12-01

To determine whether corneal sensation and dry-eye signs and symptoms after myopic laser in situ keratomileusis (LASIK) surgery with a femtosecond laser are affected by varying hinge position, hinge angle, or flap thickness. University-based academic practice, Ann Arbor, Michigan, USA. This prospective randomized contralateral-eye study evaluated eyes after bilateral myopic LASIK with a femtosecond laser (IntraLase). Superior and temporal hinge positions, 45-degree and 90-degree hinge angles, and 100 microm and 130 microm corneal flap thicknesses were compared. Postoperative follow-up at 1 week and 1, 3, 6, and 12 months included central Cochet-Bonnet esthesiometry, the Ocular Surface Disease Index questionnaire, a Schirmer test with anesthesia, tear breakup time (TBUT), corneal fluorescein staining, and conjunctival lissamine green staining. The study evaluated 190 consecutive eyes (95 patients). Corneal sensation was reduced at all postoperative visits, with improvement over 12 months (P<.001). There was no difference in corneal sensation between the different hinge positions, angles, or flap thicknesses at any time point. The overall ocular surface disease index score was increased at 1 week, 1 month, and 3 months (P<.0001, P<.0001, and P = .046, respectively). The percentage of patients with a TBUT longer than 10 seconds was significantly lower at 1 week and 1 month (P<.0001). Dry-eye syndrome after myopic LASIK with a femtosecond laser was mild and improved after 3 months. Corneal flap hinge position, hinge angle, and thickness had no effect on corneal sensation or dry-eye syndrome.

Corneal biomechanical properties in floppy eyelid syndrome.

PubMed

Muniesa, MaJesús; Muniesa Royo, MaJesús; March, Ana; March de Ribot, Ana; Sánchez-de-la-Torre, Manuel; Huerva, Valetín; Huerva Escanilla, Valetín; Jurjo, Carmen; Jurjo Campo, Carmen; Barbé, Ferran; Barbé Illa, Ferran

2015-05-01

To determine corneal biomechanical properties in patients with floppy eyelid syndrome (FES) and to compare them with eyes of controls. This case-control study included 208 eyes (72 eyes with FES and 136 without FES) of 107 patients (37 patients with FES and 70 without FES). Patients underwent a complete clinical eye examination that included corneal biomechanical evaluation carried out with the Reichert Ocular Response Analyzer. Corneal hysteresis (CH), corneal resistance factor (CRF), central corneal thickness (CCT), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc) were evaluated. Mean CH was significantly lower in patients with FES than in those without FES (9.51 ± 1.56 vs. 11.66 ± 9.11; P < 0.001). These results remained statistically significant after adjusting for age and apnea-hypoapnea index (AHI) (P = 0.028). Mean CRF was 10.02 ± 2.08 in the group of patients with FES and 11.21 ± 5.36 in the group of patients without FES (P = 0.001). Mean IOPcc was 17.7 ± 4.8 in patients with FES and 16.3 ± 4.4 in those without FES (P = 0.036). After adjusting for age and AHI, these differences in CRF and IOPcc were not statistically significant (P = 0.26 and P = 0.87, respectively). No statistically significant difference was found between patients with and without FES for Goldmann-correlated intraocular pressure or CCT. Patients with FES had statistically lower CH values. Our findings suggest that corneal biomechanical properties could be changed in patients with FES, reflecting additional structural changes in FES.

Biomechanical Changes After LASIK Flap Creation Combined With Rapid Cross-Linking Measured With Brillouin Microscopy.

PubMed

Randleman, J Bradley; Su, Johnny P; Scarcelli, Giuliano

2017-06-01

To evaluate the biomechanical changes occurring after LASIK flap creation and rapid corneal cross-linking (CXL) measured with Brillouin light microscopy. Porcine eyes (n = 11) were evaluated by Brillouin light microscopy sequentially in the following order: virgin state, after LASIK flap creation, and after rapid CXL. Each eye served as its own control. Depth profile of the Brillouin frequency shift was computed to reveal the depth-dependent changes in corneal stiffness. There was a statistically significant reduction of Brillouin shift (reduced corneal stiffness) after LASIK flap creation compared to virgin corneas across total corneal thickness (-0.035 GHz, P = .0195) and within the anterior stromal region (-0.104 GHz, P = .0039). Changes in the central (-0.029 GHz, P = .0391) and posterior (-0.005 GHz, P = .99) stromal regions were not significant. There was a small increase in Brillouin shift after rapid cross-linking that was not statistically or clinically significant across total corneal thickness (0.006 GHz, P = .4688 for any specific stromal region; 0.002 to 0.009 GHz, P > .46 for all). LASIK flap creation significantly reduced Brillouin shift in the anterior third of the stroma in porcine eyes. Rapid corneal cross-linking had no significant effect on Brillouin shift after LASIK flap creation in porcine eyes. With further validation, non-contact, non-perturbative Brillouin microscopy could become a useful monitoring tool to evaluate the biomechanical impact of corneal refractive procedures and corneal cross-linking protocols. [J Refract Surg. 2017;33(6):408-414.]. Copyright 2017, SLACK Incorporated.

Effects of Microgravity on Quail Eye Development

NASA Technical Reports Server (NTRS)

Conrad, Gary W.

1996-01-01

During embryonic development, the most exposed tissue of the eye, the cornea, becomes differentially bulged outward because of constant intraocular pressure (IOP). The component cells of the cornea secrete a unique, paracrystalline extracellular matrix (the stroma) composed of orthogonal plies of collagen fibrils and proteoglycans. The cornea remains avascular, becomes transparent, and becomes more densely innervated than any other region on the surface of the body. Corneas from chicken embryos that flew on STS-47 contain many more cellular processes in the outermost region of the stroma (Bowman's Layer) than any corresponding region of control corneas. These processes appear to be cross-sections of cytoplasmic extensions of cells and are found in that region of Bowman's Layer immediately beneath the basal lamina of the corneal epithelium. Here, we propose to compare corneas of quail that flew in space on Mir-1 with those of ground controls to determine if the same unusual cellular processes are seen as in the space-flown chicken corneas. In the central regions of such space-flown corneas, the processes appear to be either portions of basal epithelial cells whose pseudopodial extensions have migrated down through their own basal lamina into the stroma, or corneal nerves that have innervated the corneal stroma in an unusual manner. Eyeballs of embryos fixed on Mir-1, control embryos fixed at KSC and clinostated embryos fixed at KSU, will provide corneas for this study. Electron microscopy will be used to assess the distribution of the cellular processes in Bowman's Layer in the central region of each cornea. Attempts also will be made to determine the relative glycosaminoglycan distributions in the corneal stromas by indirect immunofluorscence and to record whole-mount staining patterns of the corneal nerves.

Correlation of Handheld Infrared Skin Thermometer and Infrared Videothermography Device for Measurement of Corneal Temperature.

PubMed

Oztas, Zafer; Barut Selver, Ozlem; Akkin, Cezmi; Canturk, Ecem; Afrashi, Filiz

2016-05-01

In our study, we aimed to investigate the correlation of handheld infrared skin thermometer and videothermography device for the measurement of corneal temperature. Forty healthy individuals (80 eyes) were enrolled to the study. Participants underwent a detailed ophthalmologic examination and medical history review for excluding any ocular and systemic diseases. The measurements of the central corneal temperature were performed in a room having constant temperature, humidity, and brightness levels. To avoid any variability, all the temperature measurements were performed in the same examination room by a single examiner. The temperature was measured with a handheld infrared skin thermometer (MEDISANA, FTN) from the corneal surface. The same instrument was also used to measure the subjects' body temperature. Moreover, the subjects underwent the corneal temperature measurement by a noncontact videothermography device (Optris PI 450; Optris GmbH). The male to female ratio was 19:21 among the subjects. The mean age was 25.1±4.7 years. The mean body temperature was 36.93±0.33°C. The mean corneal temperatures measured by the handheld infrared skin thermometer and the ocular videothermography device were 36.94±0.28°C and 35.61±0.61°C, respectively (P<0.01). The mean temperature difference was 1.34±0.57°C, with a 95% confidence interval. There was a moderate correlation between the corneal temperatures measured by the 2 devices in the right, the left eyes, and both eyes, respectively (P=0.450, 0.539, 0.490). Handheld infrared skin thermometers can be used for the evaluation of the corneal temperature. These devices may provide a simple, practical, and cheaper way to detect the corneal temperature, and the widely performed corneal temperature measurements may afford us to understand the temperature variability in numerous ocular conditions in a better way.

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.

Corneal collagen cross-linking: a confocal, electron, and light microscopy study of eye bank corneas.

PubMed

Dhaliwal, Jasmeet S; Kaufman, Stephen C

2009-01-01

The purpose of this study was to evaluate morphological changes induced by corneal collagen cross-linking in a human ex vivo cornea, using confocal, electron, and light microscopy. The central epithelium was partially removed from ex vivo human corneal buttons. Riboflavin 0.1% solution was applied before ultraviolet A light treatment and then for every 2 minutes for 30 minutes while the corneas were exposed to ultraviolet A light at a wavelength of 370 nm and intensity of 3 mW/cm(2). Each cornea was evaluated using confocal, electron, and light microscopy. Confocal microscopy demonstrated normal-appearing corneas on their initial pretreatment examination, with reduced stromal detail. After treatment, a superficial layer of highly reflective spherical structures (4-10 microm) was observed. Many of these hyperreflective structures appeared up to a depth of 300 microm. The remainder of the corneal stroma and endothelium appeared normal. Electron microscopy showed keratocyte apoptotic changes to a depth of 300 microm. No observable pathologic changes were seen on histology. Based on clinical studies, corneal cross-linking is a promising treatment that appears to be safe and to halt ectatic corneal disease progression. Initial European studies used animal models to extrapolate human protocols. In conjunction with clinical studies, we believe that human ex vivo corneal studies provide a means to evaluate the structural and morphological changes associated with this procedure, within human corneas, in a manner that cannot be accomplished in vivo.

Corneal Stability following Hyperopic LASIK with Advanced Laser Ablation Profiles Analyzed by a Light Propagation Study

PubMed Central

Gharaibeh, Almutez M.; Villanueva, Asier; Mas, David; Espinosa, Julian

2018-01-01

Purpose To assess anterior corneal surface stability 12 months following hyperopic LASIK correction with a light propagation algorithm. Setting Vissum Instituto Oftalmológico de Alicante, Universidad Miguel Hernández, Alicante, Spain. Methods This retrospective consecutive observational study includes 37 eyes of 37 patients treated with 6th-generation excimer laser platform (Schwind Amaris). Hyperopic LASIK was performed in all of them by the same surgeon (JLA) and completed 12-month follow-up. Corneal topography was analyzed with a light propagation algorithm, to assess the stability of the corneal outcomes along one year of follow-up. Results Between three and twelve months postoperatively, an objective corneal power (OCP) regression of 0.39 D and 0.41 D was found for 6 mm and 9 mm central corneal zone, respectively. Subjective outcomes at the end of the follow-up period were as follows: 65% of eyes had spherical equivalent within ±0.50 D. 70% of eyes had an uncorrected distance visual acuity 20/20 or better. 86% of eyes had the same or better corrected distance visual acuity. In terms of stability, 0.14 D of regression was found. No statistically significant differences were found for all the study parameters evaluated at different postoperative moments over the 12-month period. Conclusions Light propagation analysis confirms corneal surface stability following modern hyperopic LASIK with a 6th-generation excimer laser technology over a 12-month period. PMID:29785300

The effect of anesthetic eye drop instillation on the distribution of corneal thickness.

PubMed

Sanchis-Gimeno, Juan A; Palanca-Sanfrancisco, José M; García-Lázaro, Santiago; Madrid-Costa, David; Cerviño, Alejandro

2013-05-01

To address the effect of topical instillation of oxybuprocaine on the relative distribution of corneal thickness (CT) in young healthy subjects. Prospective study involving 30 eyes of 30 emmetropic subjects (24 ± 3 years). Corneal thickness measurements were carried out before and 3 minutes after the instillation of oxybuprocaine 4% using slit-scanning corneal topography (Orbscan topography system II). No acoustic correction factor was applied. The mean of 5 consecutive Orbscan measurements was obtained at the center and 3 mm from the visual axis in the temporal, superior, nasal, and inferior hemimeridians. No significant mean differences were found at any corneal location after anesthesia (P > 0.05). The difference between the baseline values obtained of the central, superior, inferior, nasal, and temporal cornea and those obtained after anesthesia ranged from -15 to 16 μm, from -19 to 32 μm, from -14 to 24 μm, from -20 to 33 μm, and from -31 to 18 μm, respectively. The maximum paracentral CT was never found at the temporal location before anesthesia, whereas it was never found at the inferior location after anesthesia. The minimum paracentral CT was never found in the superior location after anesthesia. Topical anesthetic eye drops induce CT increases and decreases at each corneal location; however, the differences are not significant. Nevertheless, a change in the location of the minimum and maximum paracentral thickness occurs in some individuals after corneal anesthesia.

Intraocular lens power calculations for cataract surgery after phototherapeutic keratectomy in granular corneal dystrophy type 2.

PubMed

Jung, Se Hwan; Han, Kyung Eun; Sgrignoli, Bradford; Kim, Tae-Im; Lee, Hyung Keun; Kim, Eung Kweon

2012-10-01

To investigate the predictability of various intraocular lens (IOL) power calculation methods in granular corneal dystrophy type 2 (GCD2) with prior phototherapeutic keratectomy (PTK) and to suggest the more predictable IOL power calculation method. Medical records of 20 eyes from 16 patients with GCD2, all having undergone cataract surgery after PTK, were retrospectively evaluated. Postoperative cataract refractive errors were compared with target diopters (D) using IOL power calculation methods as follows: 1) myopic and 2) hyperopic Haigis-L formula in IOLMaster (Carl Zeiss Meditec); 3) SRK/T formula using 4.5-mm zone Holladay equivalent keratometry readings (EKRs) (single-K Holladay EKRs method); 4) central keratometry power of true net power map in the Pentacam system (Oculus Optikgeräte GmbH); and 5) clinical history, Aramberri double-K, and double-K Holladay EKRs methods. Topographic status of corneal curvature after PTK was evaluated. Fourteen (70%) of 20 eyes showed central island formation after PTK. When central island was present, the mean absolute error (MAE) using the hyperopic Haigis-L formula was 0.25±0.15 D. When central island was not present, the myopic Haigis-L formula showed MAE of 0.33±0.16 D. When central island formation and IOLMaster keratometry underestimation were present, the hyperopic Haigis-L formula showed the least MAE of 0.26±0.08 D when switching the IOL-Master keratometry values equal to 4.5-mm zone Holladay EKRs. In planning for cataract surgery after PTK in GCD2, topographic analysis for central island formation is necessary. With or without central island formation, the hyperopic or myopic Haigis-L formula can be applied. When IOLMaster keratometry shows underestimation, the Haigis-L formula using 4.5-mm zone Holladay EKRs can be considered. 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.

Effect of Conus Eccentricity on Visual Outcomes After Intracorneal Ring Segments Implantation in Keratoconus.

PubMed

Gatzioufas, Zisis; Panos, Georgios D; Elalfy, Mohamed; Khine, Aye; Hamada, Samer; Lake, Damian; Kozeis, Nikos; Balidis, Miltos

2018-03-01

To investigate the potential impact of cone eccentricity on visual outcomes after Keraring (Mediphacos, Belo Horizonte, Brazil) implantation for keratoconus. Nineteen eyes from 19 patients with keratoconus who underwent femtosecond laser-assisted Keraring implantation for keratoconus were included in this retrospective study. Uncorrected visual acuity (UDVA), corrected visual acuity (CDVA), keratometric readings, central corneal thickness, maximum keratometric distance from corneal apex (DKmax), corneal thinnest point from corneal apex (DTh), and coma were evaluated preoperatively and 6 months after the Keraring implantation. DKmax and DTh were used as metrics reflecting the eccentricity of the cone. UDVA, CDVA, keratometric readings, and coma improved at 6 months postoperatively. However, there was no correlation between DKmax or DTh and visual outcomes at 6 months postoperatively. The data did not show any impact of the cone eccentricity on visual outcomes after Keraring implantation for keratoconus at 6 months postoperatively. [J Refract Surg. 2018;34(3):196-200.]. Copyright 2018, SLACK Incorporated.

Corneal thickness in dry eyes in an Iraqi population.

PubMed

Ali, Noora Mauwafak; Hamied, Furkaan M; Farhood, Qasim K

2017-01-01

Dry eye disorder is a multifactorial disease of the tears and ocular surface that results in discomfort and visual disturbance. Corneal pachymetry becomes increasingly important in refractive surgery, for the accurate assessment of intraocular pressure, and in the preoperative assessment of other ocular surgeries. To assess the effect of dry eye disorder on the central corneal thickness (CCT) by comparing with CCT of normal eyes of age-matched individuals. The total number of eyes examined was 280 (140 dry eyes from 70 patients and 140 normal eyes from 70 individuals). Pentacam (Scheimpflug imaging system) was used for measuring the CCT of all eyes. Patients with dry eye syndrome had significantly lower CCT compared to the control group ( P <0.01). Its mean was 536.5 versus 561.3, respectively. CCT of dry eyes was significantly reduced when compared with age- and gender-matched population. This result can be attributed to chronic desiccation by the inflammatory mediators in dry eyes, leading to corneal thinning.

In vivo laser confocal microscopic analysis of corneal K-structures after keratorefractive surgery (LASIK and epi-LASIK).

PubMed

Yokogawa, Hideaki; Kobayashi, Akira; Tagawa, Kosaku; Sugiyama, Kazuhisa

2010-01-01

To demonstrate alterations of corneal K-structures (sub-Bowman's fibrous structures) after keratorefractive surgery by in vivo laser confocal microscopy and to look for association of K-structures with fluorescein-stained anterior corneal mosaic (ACM). Five patients (nine eyes) participated in this study. For four patients, one eye was evaluated after laser in situ keratomileusis (LASIK) and the other after epipolis-laser in situ keratomileusis (epi-LASIK). For one patient, the left eye was evaluated after epithelial debridement. A photograph of the ACM was obtained. Central corneal regions were scanned by Heidelberg Retina Tomograph 2 Rostock Cornea Module (Heidelberg Engineering GmbH, Heidelberg, Germany). The ACM and K-structures disappeared in all corneas after epi-LASIK, but not after LASIK and epithelial debridement cornea. The presence of K-structures and ACM may be an index to identify eyes that had a previous refractive surgical procedure (surface ablation or LASIK) and be a health index of Bowman layer and adjacent anterior stroma. Copyright 2010, SLACK Incorporated.

Effect of Glyceraldehyde Cross-Linking on a Rabbit Bullous Keratopathy Model.

PubMed

Wang, Mengmeng

2015-01-01

Background. To evaluate the effects of corneal glyceraldehyde CXL on the rabbit bullous keratopathy models established by descemetorhexis. Methods. Fifteen rabbits were randomly divided into five groups. Group A (n = 3) is the control group. The right eyes of animals in Groups B,C, D, and E (n = 3, resp.) were suffered with descemetorhexis procedures. From the 8th day to the 14th day postoperatively, the right eyes in Groups C and D were instilled with hyperosmolar drops and glyceraldehyde drops, respectively; the right eyes in Group E were instilled with both hyperosmolar drops and glyceraldehyde drops. Central corneal thickness (CCT), corneal transparency score, and histopathological analysis were applied on the eyes in each group. Results. Compared with Group A, statistically significant increase in CCT and corneal transparency score was found in Groups B, C, D, and E at 7 d postoperatively (P < 0.05) and in Groups C, D, and E at 14 d postoperatively (P < 0.05). Conclusion. Chemical CXL technique using glyceraldehyde improved the CCT and corneal transparency of the rabbit bullous keratopathy models. Topical instillation with glyceraldehyde and hyperosmolar solutions seems to be a good choice for the bullous keratopathy treatment.

Corneal cut closure using temperature-controlled CO2 laser soldering system.

PubMed

Tal, Kfir; Strassmann, Eyal; Loya, Nino; Ravid, Avi; Kariv, Noam; Weinberger, Dov; Katzir, Abraham; Gaton, Dan D

2015-05-01

We aimed to evaluate the effectiveness of temperature-controlled laser soldering for repair of large perforated corneas in a porcine model. Eight Yorkshire pigs aged 6 months underwent 6-mm-deep 180° crescent-shaped trephination of the central corneas. Right corneal injuries were repaired by placement of 47 % bovine albumin along the cut followed by CO2 laser soldering (power density 16 W/cm(2)) to a target temperature of 65(°). Left corneal injuries were repaired with 10/0 nylon sutures. The groups were compared for operative time, leakage, and histopathological findings. Mean tissue temperature was 63 ± 4 °C. Mean operative time was 31.57 ± 2.8 min in laser-soldered eyes and 41.38 ± 2.3 min in controls (p < 0.0001, unpaired Student's t test). Compared to controls, the soldered corneas had less neovascularization, complete re-epithelization, and mild stromal inflammation. There was no leakage in either group. Combined CO2 laser and radiometer is effective for the in vivo repair of corneal cuts. These results have important implications for modern corneal surgery. Further studies are needed in the clinical setting.

In vivo laser confocal microscopic analysis of murine cornea and lens microstructures.

PubMed

Yuasa, Masashi; Kobayashi, Akira; Yokogawa, Hideaki; Sugiyama, Kazuhisa

2008-01-01

The purpose of the current study is to investigate in vivo microstructures of anterior segments of normal murine eyes by new-generation in vivo laser confocal microscopy. Twenty-six corneas and lenses from 13 mice were analyzed by in vivo laser confocal microscopy. Murine corneal superficial cells formed a polygonal cell pattern, with a mean cell density of 577 +/- 115 cells/mm2 (mean +/- standard deviation). Corneal basal epithelial cells had dark cytoplasm and were closely organized (9,312 +/- 1,777 cells/mm2). Sub-basal nerve fiber bundles were arranged in a whorl pattern, with both clockwise and counter-clockwise patterns. In the stroma, keratocytes were observed as numerous reflective stellate structures. The endothelial cells were organized in a honeycomb pattern (2,463 +/- 292 cells/mm2). Deeper inside the eye, murine lens epithelial cells were organized in a regular pattern (4,168 +/- 636 cells/mm2) and numerous lens fibers were observed. In vivo laser confocal microscopy can provide high-resolution images of all corneal layers and lens structures of mice without sacrificing animals or tissue preparation.

Efficient numerical modeling of the cornea, and applications

NASA Astrophysics Data System (ADS)

Gonzalez, L.; Navarro, Rafael M.; Hdez-Matamoros, J. L.

2004-10-01

Corneal topography has shown to be an essential tool in the ophthalmology clinic both in diagnosis and custom treatments (refractive surgery, keratoplastia), having also a strong potential in optometry. The post processing and analysis of corneal elevation, or local curvature data, is a necessary step to refine the data and also to extract relevant information for the clinician. In this context a parametric cornea model is proposed consisting of a surface described mathematically by two terms: one general ellipsoid corresponding to a regular base surface, expressed by a general quadric term located at an arbitrary position and free orientation in 3D space and a second term, described by a Zernike polynomial expansion, which accounts for irregularities and departures from the basic geometry. The model has been validated obtaining better adjustment of experimental data than other previous models. Among other potential applications, here we present the determination of the optical axis of the cornea by transforming the general quadric to its canonical form. This has permitted us to perform 3D registration of corneal topographical maps to improve the signal-to-noise ratio. Other basic and clinical applications are also explored.

Evaluation of Corneal Biomechanical Properties in Patients With Thyroid Eye Disease Using Ocular Response Analyzer.

PubMed

Moghimi, Sasan; Safizadeh, Mona; Mazloumi, Mehdi; Hosseini, Hamid; Vahedian, Zakieh; Rajabi, Mohammad T

2016-03-01

To assess variations in the corneal biomechanical properties in thyroid eye disease (TED) patients using ocular response analyzer (ORA). In this observational cross-sectional study, 75 patients with TED and 57 healthy subjects were enrolled. The mean age of the patients and healthy subjects were 47.50±1.55 and 43.6±1.23 years, respectively (P=0.06). All study participants underwent comprehensive ophthalmologic examination, Goldmann applanation tonometry (GAT), corneal pachymetry, and corneal biomechanical analysis using ORA. Corneal hysteresis (CH), corneal resistance factor (CRF), cornea-compensated IOP value (IOPcc), and Goldmann-corrected IOP value (IOPg) were measured with ORA. Central corneal thickness (CCT) in patients group (536.18±36.20 μm) and control group (539.22±28.83 μm) were not significantly different (P=0.1). In TED group, the IOPcc (20.23±0.54 mm Hg) was significantly higher than both IOP-GAT (17.54±0.49 mm Hg, P<0.001) and IOPg (18.35±0.52, P<0.001). CH in TED patients (9.01±0.20) was significantly lower compared with CH in healthy subjects (10.45±0.21) (P<0.001). Although CRF was lower in TED patients (10.06±0.16) in comparison with normal subjects (10.42±0.29), this difference was not statistically significant (P=0.25). Both CH and CRF were positively correlated with CCT (r=0.52, P<0.001 and r=0.62, P<0.001, respectively) in TED group. In TED patients, CH seems to be lower than in normal subjects. GAT might underestimate the IOP due to differences in corneal properties of cornea in TED patients.

Effect of femtosecond and microkeratome flaps creation on the cornea biomechanics during laser in situ keratomileusis: one year follow-up

PubMed Central

Sun, Qian; Deng, Zheng-Zheng; Zhou, Yue-Hua; Zhang, Jing; Peng, Xiao-Yan

2016-01-01

AIM To compare the corneal biomechanical outcomes at one year after laser in situ keratomileusis (LASIK) with the flaps created by Ziemer and Moria M2 microkeratome with 110 head and -20 blade. METHODS Totally 100 eyes of 50 consecutive patients were enrolled in this prospective study and divided into two groups for corneal flaps created by ZiemerFemto LDV and Moria M2 microkeratome with 110 head and -20 blade. Corneal biomechanical properties including cornea resistance factor (CRF) and cornea hysteresis (CH) were measured before and 1, 3, 6, 12mo after surgery by ocular response analyzer. Central cornea thickness and corneal flap thickness were measured by optical coherence tomography. RESULTS The ablation depth (P=0.693), residual corneal thickness (P=0.453), and postoperative corneal curvature (P=0.264) were not significant different between Ziemer group and Moria 110-20 group after surgery. The residual stromal bed thickness, corneal flap thickness, CH and CRF at 12mo after surgery were significant different between Ziemer group and Moria 110-20 group (P<0.01);Ziemer group gained better corneal biomechanical results. The CRF and CH increased gradually from 1 to 12mo after surgery in Ziemer group, increased from 1 to 6mo but decreased from 6 to 12mo in Moria 110-20 group. Both CRF and CH at one year after surgery increased with the increasing of residual cornea thickness; pre-LASIK CRF, CRF also increased with residual stromal bed thickness, while CH decreased with the increasing of pre-LASIK intraocular pressure and cornea flap thickness (P<0.01). CONCLUSION In one year follow-up, femtosecond laser can provide better cornea flaps with stable cornea biomechanics than mechanical microkeratome. PMID:27803856

Corticosteroids for bacterial keratitis: the Steroids for Corneal Ulcers Trial (SCUT).

PubMed

Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V; Ray, Kathryn J; Hong, Kevin C; Oldenburg, Catherine E; Lee, Salena M; Zegans, Michael E; McLeod, Stephen D; Lietman, Thomas M; Acharya, Nisha R

2012-02-01

To determine whether there is a benefit in clinical outcomes with the use of topical corticosteroids as adjunctive therapy in the treatment of bacterial corneal ulcers. Randomized, placebo-controlled, double-masked, multicenter clinical trial comparing prednisolone sodium phosphate, 1.0%, to placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and received topical moxifloxacin for at least 48 hours before randomization. The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months from enrollment. Secondary outcomes included infiltrate/scar size, reepithelialization, and corneal perforation. Between September 1, 2006, and February 22, 2010, 1769 patients were screened for the trial and 500 patients were enrolled. No significant difference was observed in the 3-month BSCVA (-0.009 logarithm of the minimum angle of resolution [logMAR]; 95% CI, -0.085 to 0.068; P = .82), infiltrate/scar size (P = .40), time to reepithelialization (P = .44), or corneal perforation (P > .99). A significant effect of corticosteroids was observed in subgroups of baseline BSCVA (P = .03) and ulcer location (P = .04). At 3 months, patients with vision of counting fingers or worse at baseline had 0.17 logMAR better visual acuity with corticosteroids (95% CI, -0.31 to -0.02; P = .03) compared with placebo, and patients with ulcers that were completely central at baseline had 0.20 logMAR better visual acuity with corticosteroids (-0.37 to -0.04; P = .02). We found no overall difference in 3-month BSCVA and no safety concerns with adjunctive corticosteroid therapy for bacterial corneal ulcers. Adjunctive topical corticosteroid use does not improve 3-month vision in patients with bacterial corneal ulcers. clinicaltrials.gov Identifier: NCT00324168.

Comparison of corneal biomechanics in Sjögren's syndrome and non-Sjögren's syndrome dry eyes by Scheimpflug based device.

PubMed

Long, Qin; Wang, Jing-Yi; Xu, Dong; Li, Ying

2017-01-01

To compare the corneal biomechanics of Sjögren's syndrome (SS) and non-SS dry eyes with Corneal Visualization Scheimpflug Technology (CorVis ST). Corneal biomechanics and tear film parameters, namely the Schirmer I test value, tear film break-up time (TBUT) and corneal staining score (CSS) were detected in 34 eyes of 34 dry eye patients with SS (SSDE group) and 34 dry eye subjects without SS (NSSDE group) using CorVis ST. The differences of the above parameters between the two groups were examined, and the relationship between corneal biomechanics and tear film parameters were observed. The differences in age, sex, intraocular pressure (IOP) and central corneal thickness (CCT) were not significant between the two groups ( P >0.05). The tear film parameters had significant differences between the SSDE group and NSSDE group (all P <0.05). Patients in the SSDE group had significantly lower A1-time and HC-time, but higher DA ( P =0.01, 0.02, and 0.02, respectively) compared with the NSSDE group. In the SSDE group, DA was negatively correlated with TBUT ( rho =-0.38, P =0.03); HC-time was negatively correlated with CSS ( rho =-0.43, P =0.02). In the NSSDE group, HC-time was again negatively correlated with CSS ( rho =-0.39, P =0.02). There are differences in corneal biomechanical properties between SSDE and NSSDE. The cornea of SSDE tends to show less "stiffness", as seen by a significantly shorter A1-time and HC-time, but larger DA, compared with the cornea of NSSDE. Biomechanical parameters can be influenced by different tear film parameters in both groups.

Spherotoric bag-in-the-lens intraocular lens: power calculation and predictive misalignment nomogram.

PubMed

Gobin, Laure; Tassignon, Marie-José; Mathysen, Danny

2011-06-01

To propose a method of calculating the power of the 1-sided posterior chamber toric bag-in-the-lens (BIL) intraocular lens (IOL) and propose a misalignment nomogram to calculate the postoperative rotational misalignment or predict the effect of preoperative existing irregular corneal astigmatism. Antwerp University Hospital, Department of Ophthalmology, Antwerp, Belgium. Cohort study. The new IOL calculation formula uses the steepest corneal meridian and flattest corneal meridian separately (regular spherical IOL formula) followed by a customized A-constant approach based on the changes in the IOL principal plane depending on the spherical and cylindrical powers (thickness) of the IOL. The calculation of the remaining astigmatism (power and axis) in cases of postoperative rotational misalignment resulted in a nomogram that can also be used to predict the degree of tolerance for irregular corneal astigmatism correction at the lenticular plane. The calculation is performed using a worksheet. Because 10 degrees of misalignment would result in 35% refractive inaccuracy, it is the maximum acceptable corneal astigmatic irregularity for correction at the lenticular plane. Calculation of spherocylindrical power is specific to each toric IOL. Because the surgeon must fully understand the optical properties of the toric IOL that is going to be implanted, a comprehensive outline of a new calculation method specific to the toric BIL IOL is proposed. Primary rotational misalignment of the toric BIL IOL can be fine tuned postoperatively. Drs. Gobin and Mathysen have no 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.

Determination of corneal elasticity coefficient using the ORA database.

PubMed

Avetisov, Sergei E; Novikov, Ivan A; Bubnova, Irina A; Antonov, Alexei A; Siplivyi, Vladimir I

2010-07-01

To propose a new approach for the study of corneal biomechanics using the Reichert Ocular Response Analyzer (ORA) database, which is based on changes in velocity retardation in the central cornea at the peak of flattening. The ORA applanation curve was analyzed using a mathematical technique, which allowed calculation of the elasticity coefficient (Ke), which is primarily characteristic of the elastic properties of the cornea. Elasticity coefficient values were obtained in patients with presumably different biomechanical properties of the cornea: "normal" cornea (71 eyes, normal group), keratoconus (34 eyes, keratoconus group), LASIK (36 eyes, LASIK group), and glaucoma with elevated and compensated intraocular pressure (lOP) (38 eyes, glaucoma group). The mean Ke value in the normal group was 11.05 +/- 1.6, and the corneal thickness correlation coefficient r2 was 0.48. In the keratoconus group, the mean Ke value was 4.91 +/- 1.87 and the corneal thickness correlation coefficient r2 was 0.47. In the LASIK group, Ke and r2 were 5.99 +/- 1.18 and 0.39, respectively. In the glaucoma group, the same eyes that experienced a two-fold reduction in lOP developed a statistically significant reduction in the Ke (1.06 times lower), whereas their corneal hysteresis value increased 1.25 times. The elasticity coefficient calculated using the ORA applanation curve can be used in the evaluation of corneal biomechanical properties.

Neovascular growth in an experimental alkali corneal burn model.

PubMed

Figueroa-Ortiz, L C; Martín Rodríguez, O; García-Ben, A; García-Campos, J

2014-08-01

To analyse the length and area of corneal surface occupied by vessels, and their location in an experimental model of alkali burn-induced corneal neovascularization. An injury to the central cornea of the right eye in 91 Sprague-Dawley rats was induced using a silver nitrate pencil. The rats were divided in 7 groups that were sacrificed 2, 4, 6, 8, 10, 12 and 14 days post-injury, and then perfused with a mixture of Chinese ink in PBS -phosphate buffer saline-. Corneas were flat-mounted processed and divided in 4 quadrants. Corneal neovascular growth parameters (length and area) and the location of these vessels were performed blind. The results were statistically analysed. Neovascular growth was observed from day 2, reaching its maximum peak in length and area on the 12th day post-injury. A slight reduction in corneal neovascularization was observed after this day. The vessels were initially located in the middle third of the stroma and tended to be observed in the anterior third during the course of the experiment. Neovascularisation was observed on day 2 post-injury in all sectors of corneal surface. Neovascular growth was uniform during the experiment. Neovessels were located in the middle and anterior third of the cornea. Copyright © 2012 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

Could adverse effects and complications of selective laser trabeculoplasty be decreased by low-power laser therapy?

PubMed

Paiva, Alexandre de Carvalho Mendes; da Fonseca, Adenilson de Souza

2017-11-30

Selective laser trabeculoplasty (SLT) has been used for treatment of primary open-angle glaucoma, ocular hypertension, pigmenter and pseudoexfoliative glaucoma being considered a low-risk procedure. Therefore, transitory and permanent adverse effects have been reported, including corneal changes, subclinical edema, and reduction in endothelial cells and in central corneal thickness. Despite rarer, serious corneal complications after SLT can be permanent and lead to visual impairment, central corneal haze, opacity and narrowing. The mechanism involves increase of vasoactive and chemotactic cytokines causing inflammatory infiltrate, destruction of stromal collagen by fibroblasts and increase of matrix metalloproteinases type 2, which impair reepithelization. SLT also increases free radical production and reduces antioxidant enzymes, resulting in endothelium damages. Low-power laser therapy (LPLT) has been used in regenerative medicine based on its biostimulatory and anti-inflammatory effects. Biostimulation occurs through the interaction of laser photons with cytochrome C oxidase enzyme, which activates intracellular biochemical cascades causing synthesis of a number of molecules related to anti-inflammatory, regenerative effects, pain relief and reduction in edema. It has been showed that LPLT reduces gene expression related to pro-inflammatory cytokines and matrix metalloproteinases, and it increases expression of growth factors related to its proliferative and healing actions. Although radiations emitted by low-power lasers are considered safe and able to induce therapeutic effects, researches based on experimental models for glaucoma could bring important data if LPLT could be an alternative approach to improve acceptation for patients undergoing SLT.

The corneal nerve density in the sub-basal plexus decreases with increasing myopia: a pilot study.

PubMed

Harrison, Wendy W; Putnam, Nicole M; Shukis, Christine; Nguyen, Evelyn; Reinard, Kristen; Hundelt, Elizabeth; Vardanyan, Galina; Gabai, Celine; Yevseyenkov, Vladimir

2017-07-01

Myopia can cause many changes in the health of the eye. As it becomes more prevalent worldwide, more patients seek correction in the form of glasses, contact lenses and refractive surgery. In this study we explore the impact that high myopia has on central corneal nerve density by comparing sub basal nerve plexus density measured by confocal microscopy in a variety of refractive errors. Seventy healthy adult subjects between the ages of 21-50 years participated in this study. The study took place in two phases with no overlapping subjects (n = 30 phase 1 and n = 40 phase 2). In both phases an autorefraction, keratometry reading, corneal thickness measure and confocal corneal scan of the sub basal nerve plexus were performed for both eyes. There were 11 hyperopes (+0.50 to +3.50DS), six emmetropes (-0.25 to +0.50DS), 30 low myopes (-5.50 to -0.50DS), and 23 high myopes (-5.50DS and above). In the second phase of the study additional tests were performed including an axial length, additional corneal scans, and a questionnaire that asked about age of first refractive correction and contact lens wear. Corneal nerves were imaged over the central cornea with a Nidek CS4 confocal microscope (460 × 345 μm field). Nerves were evaluated using the NeuronJ program for density calculation. One eye was selected for inclusion based on image quality and higher refractive error (more myopic or hyperopic). As myopia increased, nerve density decreased (t 1  = 3.86, p < 0.001). We also note a decrease in data scatter above -7 D. The relationship between axial length values and nerve density was also significant and the slope was not as robust as refractive error (t 1  = 2.4, p < 0.04). As expected there was a significant difference between the four groups in axial length (F 3  = 19.9, p < 0.001) and age of first refractive correction of the myopic groups (14.9 vs 11.5 years; t 46  = 2.99 p < 0.01). There was no difference in keratometry readings or corneal thickness between the groups (F 3  = 0.6, p = 0.66 and F 3  = 1.2, p = 0.33 respectively). Corneal nerve density in the sub-basal plexus decreased with increasing myopia. This could have implications for corneal surgery and contact lens wear in this patient population. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Omega-3 supplementation is neuroprotective to corneal nerves in dry eye disease: a pilot study.

PubMed

Chinnery, Holly R; Naranjo Golborne, Cecilia; Downie, Laura E

2017-07-01

To investigate whether oral, long-chain omega-3 (ω-3) essential fatty acid (EFA) supplementation, for 3 months, induces changes to the central corneal sub-basal nerve plexus in dry eye disease and whether nerve alterations correlate with clinical findings. This prospective, comparative study involved the final 12 participants enrolled in a randomised, double-masked, placebo-controlled clinical trial of 60 participants with moderate dry eye disease. Participants received either placebo (olive oil 1500 mg/day; n = 4) or ω-3 EFA supplements (~1000 mg/day eicosapentaenoic acid + ~500 mg/day docosahexaenoic acid; n = 8) for 90 days. The main outcome measure was the mean change in central corneal sub-basal plexus nerve parameters between days one and 90, quantified using in vivo confocal microscopy. Secondary outcomes included mean change in tear osmolarity, corneal dendritic cell density and basal epithelial cell density. Compared with baseline, the reduction in OSDI score and tear osmolarity at day 90 were greater in the ω-3 EFA group than the placebo group (OSDI: ω-3 EFA, mean ± SEM: -15.6 ± 2.8 vs placebo: -2.8 ± 4.1 units, t 5 = 2.6, p = 0.04; tearosmolarity: ω-3 EFA: -22.63 ± 5.7 vs placebo: -8 ± 2.7 mOsmol/L, t 9 = 2.3, p = 0.04). At day 90, corneal total nerve branch density (CTBD: 91.1 ± 8.6 vs 45.1 ± 13.4 branches/mm 2 , F 1,10 = 14, p = 0.004) and corneal nerve branch density on the main fibre (CNBD: 63.4 ± 6.5 vs 27.9 ± 11.5 branches/mm 2 , F 1,10 = 6, p = 0.03) were higher in the ω-3 EFA group compared with placebo. Relative to day 1, CNBD (branches/mm 2 ) increased at day 90 in the ω-3 EFA group (+20.0 ± 9.2, t 8 = 3.2 p = 0.01) compared with placebo (-10.8 ± 3.2). Similar changes were evident for corneal nerve fibre length (CNFL, mm/mm 2 ), which increased from baseline at day 90 in the omega-3 EFA group (+2.9 ± 1.6, t 8 = 3.4 p = 0.01) compared with placebo (-2.7 ± 0.5). There was a negative correlation between CTBD and tear osmolarity (r 10 = -0.70, p = 0.01). No significant changes were observed for basal epithelial cell or corneal dendritic cell density. These pilot study findings suggest that ω-3 EFA supplementation imparts neuroprotective effects in the corneal sub-basal plexus that correlate with the extent of tear osmolarity normalisation. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Anti-CD40 antibody-mediated costimulation blockade promotes long-term survival of deep-lamellar porcine corneal grafts in non-human primates.

PubMed

Kim, Jaeyoung; Kim, Dong Hyun; Choi, Hyuk Jin; Lee, Hyun Ju; Kang, Hee Jung; Park, Chung-Gyu; Hwang, Eung-Soo; Kim, Mee Kum; Wee, Won Ryang

2017-05-01

Corneal xenotransplantation is an effective solution for the shortage of human donor corneas, and the porcine cornea may be a suitable candidate for the donor cornea because of its optical similarity with humans. However, it is necessary to administer additional immunosuppressants to overcome antigenic differences. We aimed to investigate the feasibility of porcine corneas with anti-CD40 antibody-mediated costimulation blockade in a clinically applicable pig-to-non-human primate corneal xenotransplantation model. Five Chinese rhesus macaques underwent deep-lamellar corneal transplantation using clinically acceptable sized (7.5 mm diameter) porcine corneal grafts. The anti-CD40 antibody was intravenously administered on a programmed schedule. Graft survival, central corneal thickness, and intraocular pressure were evaluated. Changes in effector and memory T and B cell subsets and anti-αGal and donor-specific antibodies were investigated in the blood, and the changes in complement levels in the aqueous humor and blood were evaluated. Memory cell profiles in the anti-CD40 antibody-treated group were compared with those from the anti-CD154 antibody-treated group or rejected controls presented in our previous report. The changes in anti-αGal, non-αGal, and donor-specific antibodies after 6 months were compared with baseline values. Anti-CD40 antibody-mediated costimulation blockade resulted in the successful survival of xenocorneal grafts (>389, >382, >236, >201, and >61 days), with 80% reaching 6 months of survival. Injection of anti-CD40 antibody considerably reduced the infiltration of inflammatory cells into the grafts and significantly blocked the complement response in the aqueous humor (P=.0159, Mann-Whitney U test). Systemic expansion of central or effector memory T cells was abrogated in the anti-CD40 antibody-treated primates compared with those in the rejected controls (P<.05, Mann-Whitney U test) or those in the anti-CD154 antibody-treated primates (P>.05, Mann-Whitney U test). The levels of anti-αGal, non-αGal, and donor-specific antibodies at 6 months were not significantly increased compared with baseline levels (P>.05, Wilcoxon signed rank test). An anti-CD40 antibody-mediated blockade appears to be effective immunosuppressive approach for porcine corneal deep-lamellar xenotransplantation in primates. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Correction on the distortion of Scheimpflug imaging for dynamic central corneal thickness

NASA Astrophysics Data System (ADS)

Li, Tianjie; Tian, Lei; Wang, Like; Hon, Ying; Lam, Andrew K. C.; Huang, Yifei; Wang, Yuanyuan; Zheng, Yongping

2015-05-01

The measurement of central corneal thickness (CCT) is important in ophthalmology. Most studies concerned the value at normal status, while rare ones focused on its dynamic changing. The commercial Corvis ST is the only commercial device currently available to visualize the two-dimensional image of dynamic corneal profiles during an air puff indentation. However, the directly observed CCT involves the Scheimpflug distortion, thus misleading the clinical diagnosis. This study aimed to correct the distortion for better measuring the dynamic CCTs. The optical path was first derived to consider the influence of factors on the use of Covis ST. A correction method was then proposed to estimate the CCT at any time during air puff indentation. Simulation results demonstrated the feasibility of the intuitive-feasible calibration for measuring the stationary CCT and indicated the necessity of correction when air puffed. Experiments on three contact lenses and four human corneas verified the prediction that the CCT would be underestimated when the improper calibration was conducted for air and overestimated when it was conducted on contact lenses made of polymethylmethacrylate. Using the proposed method, the CCT was finally observed to increase by 66±34 μm at highest concavity in 48 normal human corneas.

Ophthalmic parameters in adult lowland paca (Cuniculus paca) raised in captivity.

PubMed

Balthazar da Silveira, Camila P; Lima, Tiago B; Crivelaro, Roberta M; de Lacerda, Luciana C C; Pádua, Ivan R M; Renzo, Roberta; de Barros Sobrinho, Alexandre A F; Oliveira, Fabrício S; Aldrovani, Marcela; Laus, José L

2018-01-01

To investigate the ophthalmic parameters of lowland pacas, including the anatomic features, tear production, intraocular pressure, central corneal thickness, and morphology of the corneal endothelium. Thirteen adult, anesthetized Cuniculus paca. Eyes were evaluated using slit-lamp biomicroscopy, the Schirmer tear test I, digital applanation tonometry, binocular indirect ophthalmoscopy, and noncontact specular microscopy. The biomicroscopy findings showed blue/brown pigmented bulbar conjunctivae, well-developed cilia (only in the upper eyelid margin), superior and inferior lacrimal puncta, brown irides, round pupils, and vestiges of the nictitating membrane. The results of the Schirmer tear test I revealed (mean ± SD) a lacrimation rate of 4.10 ± 0.44 mm/min. The intraocular pressure was 6.34 ± 0.43 mmHg. Central corneal thickness measured by specular microscopy was 0.35 ± 0.01 mm. The mean values of density, hexagonality, and the area of the endothelial cells were 2083.15 ± 42.47 cells/mm 2 , 67.07 ± 3.30%, and 486.30 ± 9.56 μm 2 , respectively. The ocular parameters defined in this study may be used for reference in future studies and might also contribute to therapeutic approaches appropriate to this species. © 2017 American College of Veterinary Ophthalmologists.

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.

Assessment of modifications in thickness, curvatures, and volume upon the cornea caused by disposable soft contact lens wear.

PubMed

Del Águila-Carrasco, Antonio J; Domínguez-Vicent, Alberto; Pérez-Vives, Cari; Ferrer-Blasco, Teresa; Montés-Micó, Robert

2015-01-01

To assess the effect of different disposable soft contact lenses on several corneal parameters-thickness, anterior and posterior curvature, and volume-by means of a Scheimpflug imaging-based device (Pentacam HR). Diurnal variations of these parameters were taken into account. Twenty-one young, healthy subjects wore 4 different types of daily disposable soft contact lenses on 4 different days: Dailies AquaComfort Plus, SofLens, Dailies Total1, and Acuvue TruEye. The lenses had different material and water content. Pachymetry and curvature maps and corneal volume values were obtained using the Pentacam HR twice a day: one before putting the lens on and one after an 8-hour period of contact lens wear. Measurements were also taken without any contact lenses being worn. Regarding corneal thickness, the lens with the most similar behavior to the naked eye scenario was the Dailies Total1, causing a thickening of 0.2 ± 0.1% in the central zone and 0.6 ± 0.2% in the periphery. All 4 lenses caused a slight but not significant flattening in the anterior corneal curvature, whereas the posterior corneal curvature only experienced a significant but small steepening with the SofLens. The use of these lenses increased corneal volume slightly. Variations in corneal parameters seem to depend on the type of contact lens used (material, oxygen transmissibility, water content). However, the magnitude of the changes introduced by the use of soft contact lenses over the 8-hour period was small and probably not large enough to influence either visual acuity or comfort.

Contact Lens Induced Corneal Ulcer Management in a Tertiary Eye Unit in Oman - A descriptive study

PubMed Central

Shah, Rikin; Shah, Manali; Khandekar, Rajiv; Al-Raisi, Abdulatif

2008-01-01

Objectives: The corneal disease is a priority problem in Oman. We present patients with contact lens (CL) induced severe keratitis, admitted in the corneal unit of Al Nahdha Hospital in Oman. Methods: The study was conducted in 2005–2006. Ophthalmologists examined the eyes using slit lamp bio-microscope. Visual acuity was noted using Snellen’s distance vision chart. Specimens of corneal scraping and CLs were sent for culture and sensitivity tests. Patients with severe keratitis were admitted and treated with medicines. Corneal and visual statuses were noted at the time of discharge from hospital and after six weeks. Numbers, percentages and their 95% confidence intervals were calculated. Pre- and post-treatment vision were compared using a scattergram. Results: The 52 eyes of 15 males and 37 female patients with corneal ulcers were examined. Thirty-two patients were between 20 to 30 years of age. Only 13 (25%) patients had visited an ophthalmologist within 24 hours of developing severe keratitis. Seventeen (33%) had central ulcers and six (11.5%) had ulcer ≥5 mm in size. Pseudomonas was found in 29 (55.8%) of CL and corneal material scraped from the eyes of 15 (28.8%) patients. Vision was <6/60 (legally blind) in 12 (23.1%) eyes before and in five (9.6%) eyes after treatment. Twenty-six (50%) patients were lost to follow up. Conclusion: CL related severe keratitis causes visual disabilities. Prevention and proper records are essential. Treatment improves vision and hence facilities for management should be strengthened. PMID:21748073

Effect of topical administration of tramadol on corneal wound healing in rats.

PubMed

Cuvas Apan, Ozgun; Ozer, Murat Atabey; Takir, Selcuk; Apan, Alparslan; Sengul, Demet

2016-10-01

In this study, we aimed to investigate the effects of topical tramadol administration on corneal wound healing, and examine ophthalmic structures and intraocular pressure 7 days after tramadol administration. The experiments were conducted on eight male Wistar rats (250-300 g). After ophthalmic examination, epithelial cell layers in the central cornea were wounded. Rats received 30 μL of tramadol hydrochloride in one eye (Group Tramadol) and the same volume of vehicle in the other (Group Control) every 12 h for 7 days. Both eyes were stained with fluorescein dye, photographed, and wound area was calculated every 8 h until complete healing was observed. Eye blink frequency and corneal reflex tests were measured before and after drug administrations. After 7 days, slit lamp biomicroscopy, fundoscopy, Goldmann applanation tonometry, and histological evaluation were performed. There was no difference in the corneal wound healing rates between the tramadol and control groups. Reduction in wound area over time was also similar; group-time interaction was insignificant (F = 738.911; p = 0.225). Tramadol application resulted in blinking and blepharospasm for 30 s, but vehicle did not. Corneal reflex was intact and eye blink frequency test results were similar in all measurement times in both groups. Slit lamp biomicroscopy, fundoscopy, and intraocular pressures were within normal range. Corneal cells appeared unaffected by the repeated doses of tramadol for 7 days. Topical tramadol application on the cornea did not cause any side effect, except for initial temporary blinking and blepharospasm. Corneal wound healing was not affected, either.

Photorefractive keratectomy in the cat eye: biological and optical outcomes

PubMed Central

Nagy, Lana J.; MacRae, Scott; Yoon, Geunyoung; Wyble, Matthew; Wang, Jianhua; Cox, Ian; Huxlin, Krystel R.

2007-01-01

PURPOSE To quantify optical and biomechanical properties of the feline cornea before and after photorefractive keratectomy (PRK) and assess the relative contribution of different biological factors to refractive outcome. SETTING Dept. Ophthalmology, University of Rochester, Rochester, New York, U.S.A. METHODS Adult cats underwent 6D myopic or 4D hyperopic PRK over 6 or 8mm optical zones (OZ). Pre- and post-operative wavefront aberrations were measured, along with intraocular pressure, corneal hysteresis (CH), corneal resistance factor (CRF), axial length, corneal thickness and radii of curvature. Finally, post-mortem imunohistochemistry for Vimentin and α-smooth muscle actin was performed. RESULTS PRK changed ocular defocus, increased higher order aberrations and induced myofibroblast differentiation in cats. However, the intended defocus corrections were only achieved with 8mm OZs. Long-term flattening of the epithelial and stromal surfaces was noted following myopic, but nor hyperopic PRKs. Feline intraocular pressure was unaltered by PRK, but CH and CRF decreased. Over the ensuing 6 months, ocular aberrations and intraocular pressure remained stable, while central corneal thickness, CH and CRF increased back towards normal levels. CONCLUSIONS Cat corneas exhibited optical, histological and biomechanical reactions to PRK that resembled those previously described in humans, especially when optical zone size was normalized to total corneal area. However, cats exhibited significant stromal regeneration, causing a return to pre-operative corneal thickness, CH and CRF without significant regression of optical changes induced by the surgery. Thus, the principal effects of laser refractive surgery on ocular wavefront aberrations can be achieved in spite of clear, inter-species differences in corneal biology. PMID:17531702

Meta-analysis of Pentacam vs. ultrasound pachymetry in central corneal thickness measurement in normal, post-LASIK or PRK, and keratoconic or keratoconus-suspect eyes.

PubMed

Wu, Wenjing; Wang, Yan; Xu, Lulu

2014-01-01

The aim of this meta-analysis is to evaluate the central corneal thickness (CCT) measurement differences between Pentacam (Oculus Inc., Germany) and Ultrasound Pachymetry (USP) in normal (unoperated eyes , myopic and astigmatic eyes without corneal disease or topographic irregularity), after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), and keratoconic or keratoconus suspected eyes. We assess whether Pentacam and USP have similar CCT differences in normal, thinner corneas after LASIK or PRK procedures, and kerotoconic or keratoconus suspected eyes. Data sources, including PubMed, Medline, EMBASE, and Cochrane Central Registry of Controlled Trials on the Cochrane Library, were searched to find the relevant studies. Primary outcome measures were CCT measurement between Pentacam and USP. Three groups of eyes were analyzed: normal; LASIK or PRK eyes; and keratoconus suspected or keratoconic eyes. Nineteen studies describing 1,908 eyes were enrolled in the normal group. Pentacam results were 1.47 μm ,95 % confidence interval (CI) -2.32 to 5.27, higher than USP without statistically significant difference (P = 0.45). Nine studies with total 539 eyes were included in the corneas after LASIK or PRK. The mean difference in the CCT measurement with Pentacam and ultrasound pachymetry was 1.03 μm, with the 95 % CI -3.36 to 5.42, there was no statistically difference (P = 0.64). Four studies with a total of 185 eyes were included in the keratoconic eyes or keratoconus-suspect group, however,the mean difference was -6.33 μm (95 % CI -9.17 to-3.49), which was statistically different between Pentacam and ultrasound pachymetry in the CCT measurement (P < 0.0001). Pentacam offers similar CCT results to ultrasound pachymetry in normal eyes, thinner corneas after LASIK or PRK procedures. However, in keratoconic or keratoconus-suspect eyes, Pentacam slightly underestimates the central corneal thickness than does ultrasound pachymetry, which may result from the difficulty in fixation of keratoconic eyes, misalignment of Pentacam and the variation of ultrasonic velocity due to the histological deformation.

Microscopic characterization of collagen modifications induced by low-temperature diode-laser welding of corneal tissue.

PubMed

Matteini, Paolo; Rossi, Francesca; Menabuoni, Luca; Pini, Roberto

2007-08-01

Laser welding of corneal tissue that employs diode lasers (810 nm) at low power densities (12-20 W/cm(2)) in association with Indocyanine Green staining of the wound is a technique proposed as an alternative to conventional suturing procedures. The aim of this study is to evaluate, by means of light (LM) and transmission electron microscopy (TEM) analyses, the structural modifications induced in laser-welded corneal stroma. Experiments were carried out in 20 freshly enucleated pig eyes. A 3.5 mm in length full-thickness cut was produced in the cornea, and was then closed by laser welding. Birefringence modifications in samples stained with picrosirius red dye were analyzed by polarized LM to assess heat damage. TEM analysis was performed on ultra-thin slices, contrasted with uranyl acetate and lead citrate, in order to assess organization and size of type I collagen fibrils after laser welding. LM evidenced bridges of collagen bundles between the wound edges, with a loss of regular lamellar organization at the welded site. Polarized LM indicated that birefringence properties were mostly preserved after laser treatment. TEM examinations revealed the presence of quasi-ordered groups of fibrils across the wound edges preserving their interfibrillar spacing. These fibrils appeared morphologically comparable to those in the control tissue, indicating that type I collagen was not denatured during the diode laser corneal welding. The preservation of substantially intact, undenatured collagen fibrils in laser-welded corneal wounds supported the thermodynamic studies that we carried out recently, which indicated temperatures below 66 degrees C at the weld site under laser irradiation. This observation enabled us to hypothesize that the mechanism, proposed in the literature, of unwinding of collagen triple helixes followed by fibrils "interdigitation" is not likely to occur in the welding process that we set up for the corneal suturing.

Degeneration and Regeneration of Subbasal Corneal Nerves after Infectious Keratitis: A Longitudinal In Vivo Confocal Microscopy Study.

PubMed

Müller, Rodrigo T; Abedi, Farshad; Cruzat, Andrea; Witkin, Deborah; Baniasadi, Neda; Cavalcanti, Bernardo M; Jamali, Arsia; Chodosh, James; Dana, Reza; Pavan-Langston, Deborah; Hamrah, Pedram

2015-11-01

To investigate the longitudinal alterations of subbasal corneal nerves in patients with infectious keratitis (IK) during the acute phase, cessation of treatment, and the recovery phase by in vivo confocal microscopy (IVCM). Prospective, longitudinal, case-control, single-center study. Fifty-six eyes of 56 patients with the diagnosis of bacterial (n=28), fungal (n=15), or Acanthamoeba (n=13) keratitis were included in the study. Thirty eyes of 30 normal volunteers constituted the control group. Corneal sensation and serial IVCM of the central cornea were performed prospectively using the Heidelberg Retina Tomograph 3/Rostock Cornea Module (Heidelberg Engineering, Heidelberg, Germany). The IVCM images were assessed at 3 time points: at the acute phase (first visit to the cornea service), at cessation of antimicrobial treatment, and up to 6 months after the resolution of infection. Total nerve number and length, main nerve trunks, branching, and corneal sensation were assessed during the follow-up period. Corneal nerves were reduced significantly during the acute phase in eyes with IK compared with controls across all subgroups, with total nerve length of 5.47±0.69 mm/mm2 versus 20.59±1.06 mm/mm2 (P<0.0001). At the cessation of treatment, corneal nerves in patients with IK had regenerated, including total nerve length (8.49±0.94 mm/mm2; P=0.02) and nerve branch length (4.80±0.37 mm/mm2; P=0.005). During the recovery phase, after resolution of infection, corneal nerves regenerated further, including total nerve length (12.13±1.97 mm/mm2; P=0.005), main nerve trunk length (5.80±1.00 mm/mm2; P=0.01), and nerve branch length (6.33±0.76 mm/mm2; P=0.003) as compared with the acute phase, but were still significantly lower when compared with controls (P<0.05 for all parameters). Corneal degeneration and regeneration correlated with corneal sensation (r=0.47; P=0.0009). Patients with IK who sustain profound loss of corneal nerves during the acute phase of infection demonstrate increased corneal nerve density during the first 6 months after the resolution of infection. However, despite significant nerve regeneration, corneal nerve density does not recover fully and remains low compared to controls. By providing an objective methodology to monitor corneal re-innervation, IVCM adds potentially important findings that may have implications for clinical management and surgical planning. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Scanning-slit topography in patients with keratoconus.

PubMed

Módis, László; Németh, Gábor; Szalai, Eszter; Flaskó, Zsuzsa; Seitz, Berthold

2017-01-01

To evaluate the anterior and posterior corneal surfaces using scanning-slit topography and to determine the diagnostic ability of the measured corneal parameters in keratoconus. Orbscan II measurements were taken in 39 keratoconic corneas previously diagnosed by corneal topography and in 39 healthy eyes. The central minimum, maximum, and astigmatic simulated keratometry (K) and anterior axial power values were determined. Spherical and cylindrical mean power diopters were obtained at the central and at the steepest point of the cornea both on anterior and on posterior mean power maps. Pachymetry evaluations were taken at the center and paracentrally in the 3 mm zone from the center at a location of every 45 degrees. Receiver operating characteristic (ROC) analysis was used to determine the best cut-off values and to evaluate the utility of the measured parameters in identifying patients with keratoconus. The minimum, maximum and astigmatic simulated K readings were 44.80±3.06 D, 47.17±3.67 D and 2.42±1.84 D respectively in keratoconus patients and these values differed significantly ( P <0.0001 for all comparisons) from healthy subjects. For all pachymetry measurements and for anterior and posterior mean power values significant differences were found between the two groups. Moreover, anterior central cylindrical power had the best discrimination ability (area under the ROC curve=0.948). The results suggest that scanning-slit topography and pachymetry are accurate methods both for keratoconus screening and for confirmation of the diagnosis.

3D refraction correction and extraction of clinical parameters from spectral domain optical coherence tomography of the cornea.

PubMed

Zhao, Mingtao; Kuo, Anthony N; Izatt, Joseph A

2010-04-26

Capable of three-dimensional imaging of the cornea with micrometer-scale resolution, spectral domain-optical coherence tomography (SDOCT) offers potential advantages over Placido ring and Scheimpflug photography based systems for accurate extraction of quantitative keratometric parameters. In this work, an SDOCT scanning protocol and motion correction algorithm were implemented to minimize the effects of patient motion during data acquisition. Procedures are described for correction of image data artifacts resulting from 3D refraction of SDOCT light in the cornea and from non-idealities of the scanning system geometry performed as a pre-requisite for accurate parameter extraction. Zernike polynomial 3D reconstruction and a recursive half searching algorithm (RHSA) were implemented to extract clinical keratometric parameters including anterior and posterior radii of curvature, central cornea optical power, central corneal thickness, and thickness maps of the cornea. Accuracy and repeatability of the extracted parameters obtained using a commercial 859nm SDOCT retinal imaging system with a corneal adapter were assessed using a rigid gas permeable (RGP) contact lens as a phantom target. Extraction of these parameters was performed in vivo in 3 patients and compared to commercial Placido topography and Scheimpflug photography systems. The repeatability of SDOCT central corneal power measured in vivo was 0.18 Diopters, and the difference observed between the systems averaged 0.1 Diopters between SDOCT and Scheimpflug photography, and 0.6 Diopters between SDOCT and Placido topography.

New Details of the Human Corneal Limbus Revealed With Second Harmonic Generation Imaging.

PubMed

Park, Choul Yong; Lee, Jimmy K; Zhang, Cheng; Chuck, Roy S

2015-09-01

To report novel findings of the human corneal limbus by using second harmonic generation (SHG) imaging. Corneal limbus was imaged by using an inverted two-photon excitation fluorescence microscope. Laser (Ti:Sapphire) was tuned at 850 nm for two-photon excitation. Backscatter signals of SHG and autofluorescence (AF) were collected through a 425/30-nm emission filter and a 525/45-emission filter, respectively. Multiple, consecutive, and overlapping image stacks (z-stack) were acquired for the corneal limbal area. Two novel collagen structures were revealed by SHG imaging at the limbus: an anterior limbal cribriform layer and presumed anchoring fibers. Anterior limbal cribriform layer is an intertwined reticular collagen architecture just beneath the limbal epithelial niche and is located between the peripheral cornea and Tenon's/scleral tissue. Autofluorescence imaging revealed high vascularity in this structure. Central to the anterior limbal cribriform layer, radial strands of collagen were found to connect the peripheral cornea to the limbus. These presumed anchoring fibers have both collagen and elastin and were found more extensively in the superficial layers than deep layer and were absent in very deep limbus near Schlemm's canal. By using SHG imaging, new details of the collagen architecture of human corneal limbal area were elucidated. High resolution images with volumetric analysis revealed two novel collagen structures.

Removal of the basement membrane enhances corneal wound healing.

PubMed

Pal-Ghosh, Sonali; Pajoohesh-Ganji, Ahdeah; Tadvalkar, Gauri; Stepp, Mary Ann

2011-12-01

Recurrent corneal erosions are painful and put patients' vision at risk. Treatment typically begins with debridement of the area around the erosion site followed by more aggressive treatments. An in vivo mouse model has been developed that reproducibly induces recurrent epithelial erosions in wild-type mice spontaneously within two weeks after a single 1.5 mm corneal debridement wound created using a dulled-blade. This study was conducted to determine whether 1) inhibiting MMP9 function during healing after dulled-blade wounding impacts erosion development and 2) wounds made with a rotating-burr heal without erosions. Oral or topical inhibition of MMPs after dulled-blade wounding does not improve healing. Wounds made by rotating-burr heal with significantly fewer erosions than dulled-blade wounds. The localization of MMP9, β4 integrin and basement membrane proteins (LN332 and type VII collagen), immune cell influx, and reinnervation of the corneal nerves were compared after both wound types. Rotating-burr wounds remove the anterior basement membrane centrally but not at the periphery near the wound margin, induce more apoptosis of corneal stromal cells, and damage more stromal nerve fibers. Despite the fact that rotating-burr wounds do more damage to the cornea, fewer immune cells are recruited and significantly more wounds resolve completely. Copyright © 2011 Elsevier Ltd. All rights reserved.

Laser scanning in vivo confocal microscopy of the normal human corneoscleral limbus.

PubMed

Patel, Dipika V; Sherwin, Trevor; McGhee, Charles N J

2006-07-01

To elucidate the structure of the human corneoscleral limbus by in vivo laser scanning confocal microscopy and to correlate limbal epithelial dimensions and density with the central epithelium and in relation to age. Fifty adult subjects were recruited into one of two age groups: younger (age<45 years) and older (age>or=45 years). Fifty left eyes of these 50 healthy subjects were examined by laser scanning in vivo confocal microscopy, to assess the basal epithelium of the central cornea and inferior limbus. Mean epithelial cell diameter, area, and density were calculated for the central basal epithelium, limbus-corneal basal epithelium, and limbus-palisade epithelium. Data were analyzed in relation to the two age groups, group A, 30+/-6 years (n=25; mean+/-SD), and group B, 60+/-11 years (n=25; P<0.01). Mean epithelial density in the limbus-cornea and limbus-palisade regions decreased significantly with age: limbus-cornea group A=7253+/-1077 cells/mm2 group B=6614+/-987 cells/mm2, P=0.03; limbus palisade group A=5409+/-799 cells/mm2, group B=5055+/-722 cells/mm2, P=0.03). Central corneal epithelial density did not change with age: group A=6162+/-503 cells/mm2, group B=6362+/-614 cells/mm2, P=0.08. Mean epithelial density was greatest at the limbus-cornea (7010+/-1081 cells/mm2) and lowest at the limbus-palisades (5289+/-847 cells/mm2). The mean width of palisade ridges was 25.0+/-6.3 microm. This is the first study to image clearly the living human corneal limbus by laser scanning in vivo confocal microscopy and to demonstrate quantitative changes in the basal epithelium with age.

Rebamipide suppresses TNF-α production and macrophage infiltration in the conjunctiva.

PubMed

Tajima, Kazuki; Hattori, Takaaki; Takahashi, Hiroki; Katahira, Haruki; Narimatsu, Akitomo; Kumakura, Shigeto; Goto, Hiroshi

2017-12-18

To evaluate the anti-inflammatory effect of rebamipide during corneal epithelial wound healing using a mouse wound repair model. A 2-mm circular disc of the central cornea was demarcated in the right eye of C57BL/6 mice and the epithelium removed. Rebamipide 2% eyedrop was instilled onto the wounded eye 5 times a day (n = 26). Phosphate-buffered saline (PBS) was used in the control group (n = 26). Corneal and conjunctival IL-1β and TNF-α levels were measured at 6 h and 24 h postinjury by ELISA. The wounded area was evaluated by fluorescein staining at 24 h postinjury. Macrophage infiltration was assessed immunohistochemically, and TNF-α secretion from macrophages was examined in vitro. Conjunctival IL-1β and corneal IL-1β levels were not significantly different between PBS-treated and rebamipide-treated groups. However, conjunctival TNF-α level was significantly lower in the rebamipide-treated group compared with the PBS-treated group. Macrophage migration into the conjunctiva, but not into the cornea, was suppressed by rebamipide treatment. In addition, TNF-α secretion from cultured macrophages was suppressed by rebamipide in a concentration-dependent manner. Rebamipide treatment significantly accelerated corneal epithelial wound healing at 24 h postinjury. In a mouse corneal epithelial wound model, rebamipide suppressed TNF-α secretion and macrophage infiltration in the conjunctiva, which might have contributed to accelerated corneal epithelial wound healing in the first 24 h following injury. © 2017 American College of Veterinary Ophthalmologists.

Corneal Biomechanical Changes Following Toric Soft Contact Lens Wear.

PubMed

Radaie-Moghadam, Somayeh; Hashemi, Hassan; Jafarzadehpur, Ebrahim; Yekta, Abbas Ali; Khabazkhoob, Mehdi

2016-01-01

To determine the effect of using toric soft contact lenses on corneal biomechanical properties. We enrolled 33 healthy patients with mean age of 23.18 ± 4.06 and minimal cylinder power of 1 D (-1.98 ± 0.808 SD) and negative history of contact lens use; keratoconic patients were excluded from the study. Toric soft contact lenses (BIOFINITY, Comfilcon A, Coopervision, Southampton, UK) were fitted in all participants. The Ocular Response Analyzer (Reichert Ophthalmic Instruments, Depew, New York, USA) was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), and the Pentacam HR (Oculus, Inc., Lynnwood, WA, USA) was used to measure central corneal thickness (CCT) and mean keratometry (K mean) before and one week, one month, and three months after using the toric soft contact lenses. CH and CRF were decreased significantly one month after using the contact lens; mean CH decreased from 9.99 ± 1.44 to 9.59 ± 1.54 mmHg, and mean CRF decreased from 9.96 ± 1.71 to 9.63 ± 1.73 mmHg (P = 0.013 and P = 0.017, respectively). Mean CCT and K mean did not show a significant change during the period of toric soft contact lens use. CH and CRF decreased significantly one month after fitting toric soft contact lenses while CCT and Kmean did not change significantly. Corneal biomechanical parameters may alter with toric soft contact lens use and such changes may have implications with long-term use such lenses.

Effect of oxybuprocaine eye drops on corneal volume and thickness measurements.

PubMed

Rosa, Nicola; De Bernardo, Maddalena; Borrelli, Maria; Filosa, Maria Luisa; Lanza, Michele

2011-05-01

To investigate the effect of oxybuprocaine eye drops on corneal volume (CV) and corneal thickness measurements. Central corneal thickness (CCT), corneal thinnest point (CTP), and CV of 78 eyes of 78 healthy volunteers were measured with Pentacam, before and 5 min after the administration of oxybuprocaine eye drops. The fellow non-anesthetized eyes were used as control. Before topical anesthesia, the mean CCT was 546.76 ± 35.3 μm, after anesthesia, it was 547.76 ± 36.56 μm (p = 0.86). In the fellow eyes, the first mean CCT was 548.82 ± 35.2 μm and the second was 547.55 ± 35.9 μm (p = 0.82). The mean CTP before anesthesia was 543.99 ± 35.23 μm, after it was 544.89 ± 36.3 μm (p = 0.88). In the fellow eyes, the first mean CTP was 544.15 ± 35.35 μm and the second was 542.81 ± 36 μm (p = 0.81). Before topical anesthesia, the mean CV was 60.55 ± 3.84 mm, after it was 60.66 ± 3.97 mm (p = 0.86). In the fellow eyes, the first mean CV was 60.93 ± 3.87 mm and the second was 60.73 ± 4 mm (p = 0.75). Oxybuprocaine eye drops do not appear to induce a significant corneal swelling and do not affect the measurements when comparing CCT measured with optical or ultrasound devices.

Ocular Effects of Exposure to 40, 75, and 95 GHz Millimeter Waves

NASA Astrophysics Data System (ADS)

Kojima, Masami; Suzuki, Yukihisa; Sasaki, Kensuke; Taki, Masao; Wake, Kanako; Watanabe, Soichi; Mizuno, Maya; Tasaki, Takafumi; Sasaki, Hiroshi

2018-05-01

The objective of this study was to develop a model of ocular damage induced by 40, 75, and 95 GHz continuous millimeter waves (MMW), thereby allowing assessment of the clinical course of ocular damage resulting from exposure to thermal damage-inducing MMW. This study also examined the dependence of ocular damage on incident power density. Pigmented rabbit eyes were exposed to 40, 75, and 95 GHz MMW from a spot-focus-type lens antenna. Slight ocular damage was observed 10 min after MMW exposure, including reduced cornea thickness and reduced transparency. Diffuse fluorescein staining around the pupillary area indicated corneal epithelial injury. Slit-lamp examination 1 day after MMW exposure revealed a round area of opacity, accompanied by fluorescence staining, in the central pupillary zone. Corneal edema, indicative of corneal stromal damage, peaked 1 day after MMW exposure, with thickness gradually subsiding to normal. Three days after exposure, ocular conditions had almost normalized, though corneal thickness was slightly greater than that before exposure. The 50% probability of ocular damage (DD50) was in the order 40 > 95 ≈ 75 GHz at the same incident power densities.

Goldmann tonometer error correcting prism: clinical evaluation.

PubMed

McCafferty, Sean; Lim, Garrett; Duncan, William; Enikov, Eniko T; Schwiegerling, Jim; Levine, Jason; Kew, Corin

2017-01-01

Clinically evaluate a modified applanating surface Goldmann tonometer prism designed to substantially negate errors due to patient variability in biomechanics. A modified Goldmann prism with a correcting applanation tonometry surface (CATS) was mathematically optimized to minimize the intraocular pressure (IOP) measurement error due to patient variability in corneal thickness, stiffness, curvature, and tear film adhesion force. A comparative clinical study of 109 eyes measured IOP with CATS and Goldmann prisms. The IOP measurement differences between the CATS and Goldmann prisms were correlated to corneal thickness, hysteresis, and curvature. The CATS tonometer prism in correcting for Goldmann central corneal thickness (CCT) error demonstrated a reduction to <±2 mmHg in 97% of a standard CCT population. This compares to only 54% with CCT error <±2 mmHg using the Goldmann prism. Equal reductions of ~50% in errors due to corneal rigidity and curvature were also demonstrated. The results validate the CATS prism's improved accuracy and expected reduced sensitivity to Goldmann errors without IOP bias as predicted by mathematical modeling. The CATS replacement for the Goldmann prism does not change Goldmann measurement technique or interpretation.

Effects of subcutaneous and intracerebroventricular injection of physostigmine on the acute corneal nociception in rats.

PubMed

Tamaddonfard, Esmaeal; Hamzeh-Gooshchi, Nasrin

2010-01-01

The present study investigated the effects of subcutaneous (sc) and intracerebroventricular (icv) injections of physostigmine (a cholinesterase inhibitor), atropine (an antagonist of muscarinic cholinergic receptors) and hexamethonium (an antagonist of nicotinic cholinergic receptors) on the acute corneal nociception in rats. Local application of 5 M NaCl solution on the corneal surface of the eye produced a significant nociceptive behavior, characterized by eye wiping. The number of eye wipes was counted during the first 30 s. The sc (0.25, 0.5 and 1 mg/kg) and icv (1.25, 2.5, 5 and 10 μg) injections of physostigmine significantly (p < 0.05) decreased the number of eye wipes. Atropine and hexamethonium at (2 mg/kg, sc and 20 μg, icv) had no effects when used alone, however, atropine, but not hexamethonium prevented the antinociception induced by physostigmine (sc and icv). The results of this study indicate that the central muscarinic, but not nicotinic receptors might be involved in the antinociceptive effect of physostigmine in the acute corneal model of pain in rats.

A fish eye out of water: epithelial surface projections on aerial and aquatic corneas of the 'four-eyed fish' Anableps anableps.

PubMed

Simmich, Joshua; Temple, Shelby E; Collin, Shaun P

2012-03-01

Vertebrate corneas feature a variety of microprojections, to which a tear film adheres. These microprojections are formed by folds in epithelial cell membranes, which increase surface area, stabilise the tear film and enhance movement of nutritional and waste products across cell membranes. Differences in corneal microprojections among vertebrates have been correlated with habitat and differ markedly between terrestrial and aquatic species. This study investigated epithelial microprojections of both the aerial (dorsal) and aquatic (ventral) corneal surfaces of the 'four-eyed fish' Anableps anableps using scanning electron microscopy. The central region of the dorsal cornea, which projects above the water, had a density of 16,387 ± 3,995 cells per mm(2) , while the central region of the ventral cornea (underwater) had a density of 22,428 ± 6,387 cells per mm(2), a difference that suggests an environmental adaptation along the two visual axes. Both corneal surfaces were found to possess microridges rather than microvilli or microplicae characteristic of terrestrial/aerial vertebrates. Microridges were 142 ± 9 nm wide and did not differ (p = 0.757) between dorsal and ventral corneas. Microridges were consistently separated by a distance of 369 ± 9 nm across both corneas. Dorsal-ventral differences in corneal epithelial cell density in Anableps anableps suggest a difference in osmotic pressure of the two corneas. The modest differences in the microprojections indicate that the need to secure the tear film underlying each optical axis is of prime importance, due to the likelihood that a persistent layer of water normally covers both dorsal and ventral corneal surfaces and that maintaining a transparent optical pathway for vision is critical for a species prone to predation from both above and below the water's surface. © 2012 The Authors. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

Cornea Preservation Time Study: Methods and Potential Impact on the Cornea Donor Pool in the United States

PubMed Central

Szczotka-Flynn, Loretta B.; Ayala, Allison R.; Benetz, Beth A.; Gal, Robin L.; Aldave, Anthony J.; Corrigan, Michelle M.; Dunn, Steven P.; McCall, Ty L.; Pramanik, Sudeep; Rosenwasser, George O.; Ross, Kevin W.; Terry, Mark A.; Verdier, David D.

2015-01-01

Purpose: The aim of this study was to describe the aims, methods, donor and recipient cohort characteristics, and potential impact of the Cornea Preservation Time Study (CPTS). Methods: The CPTS is a randomized clinical trial conducted at 40 clinical sites (70 surgeons) designed to assess the effect of donor cornea preservation time (PT) on graft survival 3 years after Descemet stripping automated endothelial keratoplasty (DSAEK). Eyes undergoing surgery for Fuchs endothelial corneal dystrophy or pseudophakic/aphakic corneal edema were randomized to receive donor corneas stored ≤7 days or 8 to 14 days. Donor and patient characteristics, tissue preparation and surgical parameters, recipient and donor corneal stroma clarity, central corneal thickness, intraocular pressure, complications, and a reading center-determined central endothelial cell density were collected. Surveys were conducted to evaluate pre-CPTS PT practices. Results: The 1330 CPTS donors were: 49% >60 years old, 27% diabetic, had a median eye bank–determined screening endothelial cell density of 2688 cells/mm2, and 74% eye bank prepared for DSAEK. A total of 1090 recipients (1330 eyes including 240 bilateral cases) had: median age of 70 years, were 60% female, 90% white, 18% diabetic, 52% phakic, and 94% had Fuchs endothelial corneal dystrophy. Before the CPTS, 19 eye banks provided PT data on 20,852 corneas domestically placed for DSAEK in 2010 to 2011; 96% were preserved ≤7 days. Of 305 American Academy of Ophthalmology members responding to a pre-CPTS survey, 233 (76%) set their maximum PT preference at 8 days or less. Conclusions: The CPTS will increase understanding of factors related to DSAEK success and, if noninferiority of longer PT is shown, will have great potential to extend the available pool of endothelial keratoplasty donors. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT01537393. PMID:25850706

Visual rehabilitation in low-moderate keratoconus: intracorneal ring segment implantation followed by same-day topography-guided photorefractive keratectomy and collagen cross linking

PubMed Central

Zeraid, Ferial M; Jawkhab, Asma A; Al-Tuwairqi, Waleed S; Osuagwu, Uchechukwu L

2014-01-01

AIM To present the results of same-day topography-guided photorefractive keratectomy (TG-PRK) and corneal collagen crosslinking (CXL) after previous intrastromal corneal ring segment (ISCR) implantation for keratoconus. METHODS An experimental clinical study on twenty-one eyes of 19 patients aged 27.1±6.6y (range 19-43y), with low to moderate keratoconus who were selected to undergo customized TG-PRK immediately followed by same-day CXL, 9mo after ISCR implantation in a university ophthalmology clinic. Refraction, uncorrected distance visual acuities (UDVA) and corrected distance visual acuities (CDVA), keratometry (K) values, central corneal thickness (CCT) and coma were assessed 3mo after TG-PRK and CXL. RESULTS After TG-PRK/CXL: the mean UDVA (logMAR) improved significantly from 0.66±0.41 to 0.20±0.25 (P<0.05); Kflat value decreased from: 48.44±3.66 D to 43.71±1.95 D; Ksteep value decreased from 45.61±2.40 D to 41.56±2.05 D; Kaverage also decreased from 47.00±2.66 D to 42.42±2.07 D (P<0.05 for all). The mean sphere and cylinder decreased significantly post-surgery from, -3.10±2.99 D to -0.11±0.93 D and from -3.68±1.53 to -1.11±0.75 D respectively, while the CDVA, CCT and coma showed no significant changes. Compared to post-ISCR, significant reductions (P<0.05 or all) in all K values, sphere and cylinder were observed after TG-PRK/CXL. CONCLUSION Same-day combined topography-guided PRK and corneal crosslinking following placement of ISCR is a safe and potentially effective option in treating low-moderate keratoconus. It significantly improves all visual acuity, reduced keratometry, sphere and astigmatism, but causes no change in central corneal thickness and coma. PMID:25349796

Corneal endothelial cell loss and corneal biomechanical characteristics after two-step sequential or combined phaco-vitrectomy surgery for idiopathic epiretinal membrane.

PubMed

Hamoudi, Hassan; Christensen, Ulrik Correll; La Cour, Morten

2017-08-01

To assess the impact of sequential and combined surgery [cataract surgery and 23-gauge pars plana vitrectomy (PPV) with peeling] on corneal endothelium cell density (CED) and corneal biomechanical characteristics. Phakic eyes with epiretinal membrane (ERM) were prospectively allocated to (i) cataract surgery and subsequent PPV (CAT group), (ii) PPV and subsequent cataract surgery (VIT group) or (iii) phacovitrectomy (COMBI group). Eyes were examined at baseline, 1 month after each surgery, and at 3 and 12 months follow-up. Corneal endothelium cell density (CED) was assessed with non-contact specular microscopy. Pachymetry [central cornea thickness (CCT)], keratometry and cornea volume (CV) were measured with Pentacam Scheimpflug camera. Primary outcome was change in CED after 12 months; secondary outcomes were changes in CCT and CV after 12 months. Sixty-two eyes were enrolled and allocated to the three groups. The mean preoperative CED was 2776, 2794 and 2653 cells/mm 2, which decreased significantly at 12 months by 15.3, 20.0 and 19.3% in the CAT, VIT and COMBI group. There was no significant difference in percentage cell loss between the groups at final follow-up. The CED decreased significantly after cataract surgery, but was unaffected by PPV. Central cornea thickness (CCT) increased by 10 μm (p = 0.005) and CV by 1.38 mm 3 (2.3%, p < 0.001) in the COMBI group. There were no significant differences in CCT or CV between the groups at final follow-up. Combined and sequential surgery in ERM leads to a small decrease in CED. Performing cataract surgery before, after or in combination with vitrectomy did not make any significant difference with respect to final CED, CCT or CV. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Tracing the fate of limbal epithelial progenitor cells in the murine cornea.

PubMed

Di Girolamo, N; Bobba, S; Raviraj, V; Delic, N C; Slapetova, I; Nicovich, P R; Halliday, G M; Wakefield, D; Whan, R; Lyons, J G

2015-01-01

Stem cell (SC) division, deployment, and differentiation are processes that contribute to corneal epithelial renewal. Until now studying the destiny of these cells in a living mammal has not been possible. However, the advent of inducible multicolor genetic tagging and powerful imaging technologies has rendered this achievable in the translucent and readily accessible murine cornea. K14CreER(T2)-Confetti mice that harbor two copies of the Brainbow 2.1 cassette, yielding up to 10 colors from the stochastic recombination of fluorescent proteins, were used to monitor K-14(+) progenitor cell dynamics within the corneal epithelium in live animals. Multicolored columns of cells emerged from the basal limbal epithelium as they expanded and migrated linearly at a rate of 10.8 µm/day toward the central cornea. Moreover, the permanent expression of fluorophores, passed on from progenitor to progeny, assisted in discriminating individual clones as spectrally distinct streaks containing more than 1,000 cells within the illuminated area. The centripetal clonal expansion is suggestive that a single progenitor cell is responsible for maintaining a narrow corridor of corneal epithelial cells. Our data are in agreement with the limbus as the repository for SC as opposed to SC being distributed throughout the central cornea. This is the first report describing stem/progenitor cell fate determination in the murine cornea using multicolor genetic tracing. This model represents a powerful new resource to monitor SC kinetics and fate choice under homeostatic conditions, and may assist in assessing clonal evolution during corneal development, aging, wound-healing, disease, and following transplantation. © 2014 AlphaMed Press.

Orbscan II anterior elevation changes following corneal collagen cross-linking treatment for keratoconus.

PubMed

Tu, Kyaw Lin; Aslanides, Ioannis M

2009-08-01

To analyze anterior corneal elevation changes on Orbscan II following corneal collagen cross-linking (CXL) with riboflavin. This retrospective study included 8 patients (14 eyes) with keratoconus who underwent CXL, with a mean follow-up of 7 months (range: 5 to 10 months). Pre- and postoperative (at last clinic attendance) anterior elevation difference maps were examined for overall patterns of change. On preoperative maps, distances from maximum anterior elevation to pupil center and to topographic geometric center were compared between the two patterns identified. Pre- and postoperative topography, best spectacle-corrected visual acuity (BSCVA), and refraction were also compared between the two patterns. Two patterns of anterior elevation change were visually identified: (1) paracentral steepening, no change, or flattening centrally; and (2) central steepening. The preoperative maps of eyes that manifested pattern 1 had shorter mean distances for maximum anterior elevation to pupil center (1.70 vs. 2.27 mm) and maximum anterior elevation to geometric center (1.45 vs. 1.99 mm) than those that resulted in pattern 2. Mean maximum topographic simulated keratometry decreased (P = .004) and mean irregularity indices at 3 mm (P =.03) and 5 mm (P =.04) were reduced postoperatively in pattern 1 eyes; all increased in pattern 2 eyes. Mean BSCVA improved postoperatively for both patterns. Mean preoperative myopia decreased in pattern 1 eyes by 0.44 diopters (D), whereas it increased for pattern 2 eyes by 1.83 D. Corneal shape change influenced by anisotropy of collagen distribution is a factor in the outcome of CXL treatment for keratoconus.

Central Corneal Thickness Increase Due to Stromal Thickening With Diabetic Peripheral Neuropathy Severity.

PubMed

Kumar, Navasuja; Pop-Busui, Rodica; Musch, David C; Reed, David M; Momont, Anna C; Hussain, Munira; Raval, Nilesh; Moroi, Sayoko E; Shtein, Roni

2018-06-19

To investigate the relationship between central corneal thickness (CCT) and diabetes disease severity among patients with diabetic peripheral neuropathy (DPN) compared with controls. In this cross-sectional study, 34 participants were examined. DPN status was assessed by clinical examination, nerve conduction studies, and quantitative sensory testing. All participants underwent comprehensive eye examination that included intraocular pressure measured by Goldmann applanation tonometry. CCT was measured by ultrasound pachymetry, and the thickness of corneal layers was assessed by corneal confocal microscopy. Association of CCT and DPN was examined using ANOVA. Among the 34 participants, there were 9 controls, 16 patients with mild DPN, and 9 patients with severe DPN. CCT was significantly increased in the DPN groups compared with controls (P = 0.0003). Mean CCT among controls was 552.7 ± 29.2 μm compared with 583.4 ± 25.0 μm in the mild DPN group and 613.3 ± 28.8 μm in the severe DPN group. In addition, stromal thickness differed significantly between the 3 study groups (P = 0.045). Mean stromal thickness among controls was 439.5 ± 23.5 μm compared with 478.9 ± 37.5 μm in the mild DPN group and 494.5 ± 39.1 μm in the severe DPN group. This study demonstrates that CCT increases with DPN severity because of an increase in stromal thickness. CCT increase associated with DPN has important clinical implications including glaucoma progression, keratoconus susceptibility, and intraocular pressure assessment and should be accounted for when evaluating patients with diabetes.

Effects of central corneal thickness on measurement of intra-ocular pressure in keratoconus and post-keratoplasty.

PubMed

Patel, S; McLaughlin, J M

1999-05-01

To measure and compare central corneal thickness (CT) and intraocular pressure (IOP) in keratoconus and post-keratoplasty subjects and examine the CT-IOP relationship. 22 keratoconus (category I: six female sixteen male, average age 27.0 range 12-47) and 19 post-keratoplasty (category II: ten female nine male average age 34.6 range 16-54) patients without other anterior segment conditions were recruited. Only one, non-contact lens wearing, eye of the patient was included for analysis. Cornea was anaesthetised with non-preserved 0.4% Benoxinate Hydrochloride. Using a randomised approach, CT was measured using a standard ultrasonic pachymeter. IOP was then measured using a standard Goldmann tonometer. At all times the tonometrist remained unaware of the corneal thickness values. The mean (+/- s.d.) values for CT and IOP respectively in the two categories were: (I), 445 (45) mu and 9.8 (2.3) mmHg, (II), 564(44) microns and 15.8 (3.9) mmHg. Differences between I and II for both CT and IOP were significant (t-test, p = 0.01). Within each category, a significant correlation between CT and IOP was not found. Pooling all pairs of data (n = 41) a significant relationship between CT and IOP was detected (r = 0.635, p = 0.0001). The results confirm the hypothesis that an eye with a thicker cornea tends to present with a higher measured IOP. In the management of keratoconus and other corneal surgical procedures, changes in CT will contribute to any apparent changes in measured IOP.

Altered corneal biomechanical properties in children with osteogenesis imperfecta.

PubMed

Lagrou, Lisa M; Gilbert, Jesse; Hannibal, Mark; Caird, Michelle S; Thomas, Inas; Moroi, Sayoko E; Bohnsack, Brenda L

2018-04-07

To evaluate biomechanical corneal properties in children with osteogenesis imperfecta (OI). A prospective, observational, case-control study was conducted on children 6-19 years of age diagnosed with OI. Patients with OI and healthy control subjects underwent complete ophthalmic examinations. Additional tests included Ocular Response Analyzer (ORA) and ultrasonic pachymetry. Primary outcomes were central corneal thickness (CCT), corneal hysteresis (CH), and corneal resistance factor (CRF). Intraocular pressure (IOP) was measured directly by either iCare or Goldmann applanation and indirectly by the ORA (Goldmann-correlated and corneal-compensated IOP). Statistically significant differences between OI and control groups were determined using independent samples t test. A total of 10 of 18 OI cases (mean age, 13 ± 4.37 years; 8 males) and 30 controls (mean age, 12.76 ± 2.62 years; 16 males) were able to complete the corneal biomechanics and pachymetry testing. Children with OI had decreased CH (8.5 ± 1.0 mm Hg vs 11.6 ± 1.2 mm Hg [P < 0.001]), CRF (9.0 ± 1.9 mm Hg vs 11.5 ± 1.5 [P < 0.001]) and CCT (449.8 ± 30.8 μm vs 568 ± 47.6 μm [P < 0.001]) compared to controls. The corneal-compensated IOP was significantly higher in OI cases (18.8 ± 3.1 mm Hg) than in controls (15.0 ± 1.6 mm Hg, P < 0.004), but there was no significant difference in Goldmann-correlated IOP (16.3 ± 4.2 mm Hg vs 15.8 ± 2.2 mm Hg). Collagen defects in OI alter corneal structure and biomechanics. Children with OI have decreased CH, CRF, and CCT, resulting in IOPs that are likely higher than measured by tonometry. These corneal alterations are present at a young age in OI. Affected individuals should be routinely screened for glaucoma and corneal pathologies. Copyright © 2018 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Change in over-refraction after scleral lens settling on average corneas.

PubMed

Bray, Chelsea; Britton, Stephanie; Yeung, Debby; Haines, Lacey; Sorbara, Luigina

2017-07-01

The purpose of this study was to determine the change in over-refraction, if any, after a scleral lens settled on the eye for 6-8 h. Sixteen patients of varying refractive errors and normal corneal curvatures (measured with Pentacam ™ Oculus) were fitted with trial Mini-Scleral Design (MSD) scleral lenses (15.8 mm diameter) in one eye. The sagittal depths of the scleral lenses were selected by adding 350 μm to the corneal sagittal heights measured at a chord length of 15 mm with the Visante ™ optical coherence tomographer (OCT) anterior segment scans and picking the closest available trial lens in the set. Initial measurements were taken 30 min after lens insertion and included an auto-refraction, subjective refraction, and best sphere refraction over the contact lens. Visual acuities and Visante ™ OCT anterior segment scans were also taken. These measurements were repeated after 6-8 h of lens wear. Over the trial wearing period, the average change in the spherical component of the over-refraction was +0.06 D (S.D. 0.17) (p = 0.16). The average change in cylinder was +0.04 D (S.D. 0.19) (p = 0.33). The average absolute change in axis was 1.06° (S.D. 12.11) (p = 0.74). The average change in best sphere was +0.13 ± 0.30 D (p = 0.12). There was no significant change in visual acuity with the best sphere over-refraction over the 6-8 h wearing period. There was a significant change in central corneal clearance over the wearing period of 83 μm (S.D. 22) (p < 0.0001). Despite a significant change in the central corneal clearance due to thinning of the fluid reservoir as the scleral lens settled (an average decrease of 83 μm after wearing the lenses for 6-8 h), there was not a statistically significant change in the subjective over-refraction (sphere, cylinder, and axis) or best sphere or visual acuity. This study has confirmed that there is no link between reduction in central corneal clearance and change in over-refraction for average corneas. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Patients with Dry Eye Disease and Low Subbasal Nerve Density are at High Risk for an Accelerated Corneal Endothelial Cell Loss

PubMed Central

Kheirkhah, Ahmad; Satitpitakul, Vannarut; Hamrah, Pedram; Dana, Reza

2016-01-01

Purpose To evaluate the changes in corneal endothelial cell density (CECD) over time in patients with dry eye disease (DED) and to correlate the endothelial cell loss with corneal subbasal nerve density. Methods This retrospective study included 40 eyes of 20 patients with DED. Laser in vivo confocal microscopy had been performed in the central cornea of both eyes at an initial visit and repeated after a mean follow-up of 33.2 ± 10.2 months. The densities of corneal endothelial cells and subbasal nerves were measured in both visits and compared with 13 eyes of 13 normal age-matched controls. Results At the initial visit, the DED group had lower densities of corneal endothelial cells (2620 ± 386 cells/mm2) and subbasal nerves (17.8 ± 7.5 mm/mm2) compared with the control group (2861 ± 292 cells/mm2 and 22.8 ± 3.0 mm/mm2, with P=0.08 and P=0.01, respectively). At the end of follow-up, although there was no significant change in subbasal nerve density (16.7 ± 7.2 mm/mm2, P=0.43), the mean CECD significantly decreased to 2465 ± 391 cells/mm2 (P=0.01), with a mean corneal endothelial cell loss of 2.1 ± 3.6% per year. The endothelial cell loss showed a statistically significant negative correlation with the initial subbasal nerve density (Rs= −0.55, P=0.02). Conclusion Patients with DED have an accelerated corneal endothelial cell loss which is more than what has been reported in the literature for normal aging. Those with lower subbasal nerve density, in particular, are at a higher risk for endothelial cell loss over time. PMID:28060067

Corticosteroids for Bacterial Keratitis

PubMed Central

Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V.; Ray, Kathryn J.; Hong, Kevin C.; Oldenburg, Catherine E.; Lee, Salena M.; Zegans, Michael E.; McLeod, Stephen D.; Lietman, Thomas M.; Acharya, Nisha R.

2013-01-01

Objective To determine whether there is a benefit in clinical outcomes with the use of topical corticosteroids as adjunctive therapy in the treatment of bacterial corneal ulcers. Methods Randomized, placebo-controlled, double-masked, multicenter clinical trial comparing prednisolone sodium phosphate, 1.0%, to placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and received topical moxifloxacin for at least 48 hours before randomization. Main Outcome Measures The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months from enrollment. Secondary outcomes included infiltrate/scar size, reepithelialization, and corneal perforation. Results Between September 1, 2006, and February 22, 2010, 1769 patients were screened for the trial and 500 patients were enrolled. No significant difference was observed in the 3-month BSCVA (−0.009 logarithm of the minimum angle of resolution [logMAR]; 95% CI, −0.085 to 0.068; P = .82), infiltrate/scar size (P = .40), time to reepithelialization (P = .44), or corneal perforation (P > .99). A significant effect of corticosteroids was observed in subgroups of baseline BSCVA (P = .03) and ulcer location (P = .04). At 3 months, patients with vision of counting fingers or worse at baseline had 0.17 logMAR better visual acuity with corticosteroids (95% CI, −0.31 to −0.02; P = .03) compared with placebo, and patients with ulcers that were completely central at baseline had 0.20 logMAR better visual acuity with corticosteroids (−0.37 to −0.04; P = .02). Conclusions We found no overall difference in 3-month BSCVA and no safety concerns with adjunctive corticosteroid therapy for bacterial corneal ulcers. Application to Clinical Practice Adjunctive topical corticosteroid use does not improve 3-month vision in patients with bacterial corneal ulcers. PMID:21987582

Inactivation of the miR-183/96/182 Cluster Decreases the Severity of Pseudomonas aeruginosa-Induced Keratitis

PubMed Central

Muraleedharan, Chithra K.; McClellan, Sharon A.; Barrett, Ronald P.; Li, Cui; Montenegro, Daniel; Carion, Thomas; Berger, Elizabeth; Hazlett, Linda D.; Xu, Shunbin

2016-01-01

Purpose The microRNA-183/96/182 cluster (miR-183/96/182) plays important roles in sensory organs. Because the cornea is replete with sensory innervation, we hypothesized that miR-183/96/182 modulates the corneal response to bacterial infection through regulation of neuroimmune interactions. Methods Eight-week-old miR-183/96/182 knockout (ko) mice and their wild-type littermates (wt) were used. The central cornea of anesthetized mice was scarred and infected with Pseudomonas aeruginosa (PA), strain 19660. Corneal disease was graded at 1, 3, and 5 days postinfection (dpi). Corneal RNA was harvested for quantitative RT-PCR. Polymorphonuclear neutrophils (PMN) were enumerated by myeloperoxidase assays; the number of viable bacteria was determined by plate counts, and ELISA assays were performed to determine cytokine protein levels. A macrophage (Mϕ) cell line and elicited peritoneal PMN were used for in vitro functional assays. Results MicroRNA-183/96/182 is expressed in the cornea, and in Mϕ and PMN of both mice and humans. Inactivation of miR-183/96/182 resulted in decreased corneal nerve density compared with wt mice. Overexpression of miR-183/96/182 in Mϕ decreased, whereas knockdown or inactivation of miR-183/96/182 in Mϕ and PMN increased their capacity for phagocytosis and intracellular killing of PA. In PA-infected corneas, ko mice showed decreased proinflammatory neuropeptides such as substance P and chemoattractant molecules, MIP-2, MCP1, and ICAM1; decreased number of PMN at 1 and 5 dpi; increased viable bacterial load at 1 dpi, but decreased at 5 dpi; and markedly decreased corneal disease. Conclusions MicroRNA-183/96/182 modulates the corneal response to bacterial infection through its regulation of corneal innervation and innate immunity. PMID:27035623

Inactivation of the miR-183/96/182 Cluster Decreases the Severity of Pseudomonas aeruginosa-Induced Keratitis.

PubMed

Muraleedharan, Chithra K; McClellan, Sharon A; Barrett, Ronald P; Li, Cui; Montenegro, Daniel; Carion, Thomas; Berger, Elizabeth; Hazlett, Linda D; Xu, Shunbin

2016-04-01

The microRNA-183/96/182 cluster (miR-183/96/182) plays important roles in sensory organs. Because the cornea is replete with sensory innervation, we hypothesized that miR-183/96/182 modulates the corneal response to bacterial infection through regulation of neuroimmune interactions. Eight-week-old miR-183/96/182 knockout (ko) mice and their wild-type littermates (wt) were used. The central cornea of anesthetized mice was scarred and infected with Pseudomonas aeruginosa (PA), strain 19660. Corneal disease was graded at 1, 3, and 5 days postinfection (dpi). Corneal RNA was harvested for quantitative RT-PCR. Polymorphonuclear neutrophils (PMN) were enumerated by myeloperoxidase assays; the number of viable bacteria was determined by plate counts, and ELISA assays were performed to determine cytokine protein levels. A macrophage (Mϕ) cell line and elicited peritoneal PMN were used for in vitro functional assays. MicroRNA-183/96/182 is expressed in the cornea, and in Mϕ and PMN of both mice and humans. Inactivation of miR-183/96/182 resulted in decreased corneal nerve density compared with wt mice. Overexpression of miR-183/96/182 in Mϕ decreased, whereas knockdown or inactivation of miR-183/96/182 in Mϕ and PMN increased their capacity for phagocytosis and intracellular killing of PA. In PA-infected corneas, ko mice showed decreased proinflammatory neuropeptides such as substance P and chemoattractant molecules, MIP-2, MCP1, and ICAM1; decreased number of PMN at 1 and 5 dpi; increased viable bacterial load at 1 dpi, but decreased at 5 dpi; and markedly decreased corneal disease. MicroRNA-183/96/182 modulates the corneal response to bacterial infection through its regulation of corneal innervation and innate immunity.

Effect of Orbital Decompression on Corneal Topography in Patients with Thyroid Ophthalmopathy

PubMed Central

Kim, Su Ah; Jung, Su Kyung; Paik, Ji Sun; Yang, Suk-Woo

2015-01-01

Objective To evaluate changes in corneal astigmatism in patients undergoing orbital decompression surgery. Methods This retrospective, non randomized comparative study involved 42 eyes from 21 patients with thyroid ophthalmopathy who underwent orbital decompression surgery between September 2011 and September 2014. The 42 eyes were divided into three groups: control (9 eyes), two-wall decompression (25 eyes), and three-wall decompression (8 eyes). The control group was defined as the contralateral eyes of nine patients who underwent orbital decompression surgery in only one eye. Corneal topography (Orbscan II), Hertel exophthalmometry, and intraocular pressure were measured at 1 month before and 3 months after surgery. Corneal topographic parameters analyzed were total astigmatism (TA), steepest axis (SA), central corneal thickness (CCT), and anterior chamber depth (ACD). Results Exophthalmometry values and intraocular pressure decreased significantly after the decompression surgery. The change (absolute value (|x|) of the difference) in astigmatism at the 3 mm zone was significantly different between the decompression group and the controls (p = 0.025). There was also a significant change in the steepest axis at the 3 mm zone between the decompression group and the controls (p = 0.033). An analysis of relevant changes in astigmatism showed that there was a dominant tendency for incyclotorsion of the steepest axis in eyes that underwent decompression surgery. Using Astig PLOT, the mean surgically induced astigmatism (SIA) was 0.21±0.88 D with an axis of 46±22°, suggesting that decompression surgery did change the corneal shape and induced incyclotorsion of the steepest axis. Conclusions There was a significant change in corneal astigmatism after orbital decompression surgery and this change was sufficient to affect the optical function of the cornea. Surgeons and patients should be aware of these changes. PMID:26352432

Corneal Nerve Morphology and Tear Film Substance P in Diabetes.

PubMed

Markoulli, Maria; You, Jingjing; Kim, Juno; Duong, Carmen L; Tolentino, Jonathan B; Karras, Joshua; Lum, Edward

2017-07-01

This work aims to characterize the relationship between tear film neuropeptide substance P and the structural integrity of the sub-basal nerve plexus in diabetes. Seventeen healthy control participants and nine participants with diabetes were recruited in this cross-sectional study. Total protein content and substance P concentrations were determined in the flush tears of participants. Corneal nerve morphology was assessed by capturing the corneal sub-basal nerve plexus using the Heidelberg Retinal Tomograph II with the Rostock Corneal Module (Heidelberg Engineering GmbH, Heidelberg, Germany) in the central cornea. Corneal nerve fiber density (CNFD) was measured using ACCMetrics (M.A. Dabbah, Imaging Science and Biomedical Engineering, Manchester, UK) on eight captured images. Comparisons between groups were made using independent samples t-tests. Correlations between parameters were analyzed using Pearson's correlations. Substance P concentrations were significantly higher in the tears of the control group compared to participants with diabetes (4150 ± 4752 and 1473 ± 1671 pg/mL, respectively, P = .047). There was no significant difference in total protein content between the groups (3.4 ± 1.8 and 2.6 ± 1.7 mg/mL in the control and diabetes groups, respectively, P = .262). CNFD was significantly lower in the participants with diabetes compared to the control group (16.1 ± 5.7 and 21.5 ± 7.0 mm/mm, respectively, P = .041). There was a moderate correlation between substance P and CNFD (r = 0.48, P = .01). Substance P is expressed at a significantly lower level in the tears of people with diabetes compared with healthy controls. The positive correlation between substance P and corneal nerve density indicates that substance P may be a potential biomarker for corneal nerve health.

Normative values for optical coherence tomography parameters in healthy children and interexaminer agreement for choroidal thickness measurements.

PubMed

Turan, Kadriye Erkan; Sekeroglu, Hande Taylan; Baytaroglu, Ata; Bezci, Figen; Karahan, Sevilay

2018-01-01

To (a) determine the normative values for optical coherence tomography (OCT) parameters such as central macular thickness, retinal nerve fiber layer thickness, and choroidal thickness in healthy children; (b) investigate the relationships of these parameters with axial length, central corneal thickness, refractive errors, and intraocular pressure; and (c) determine interexaminer agreement for choroidal thickness measurements. In this cross-sectional study, 120 healthy children aged 8-15 years underwent detailed ophthalmological examination and OCT measurements. Choroidal thickness was measured at three separate locations by two independent examiners. The mean global retinal nerve fiber layer thickness was 98.75 ± 9.45 μm (79.0-121.0). The mean central macular thickness was 232.29 ± 29.37 μm (190.0-376.0). The mean subfoveal choroidal thickness obtained by examiner 1 was 344.38 ± 68.83 μm and that obtained by examiner 2 was 344.04 ± 68.92 μm. Interexaminer agreement was between 99.6%-99.8% for choroidal thickness at three separate locations. Central macular thickness increased with axial length (r=0.245, p=0.007). Choroidal thickness increased with age (r=0.291, p=0.001) and decreased with axial length (r=-0.191, p=0.037). Global retinal nerve fiber layer thickness decreased with axial length (r=-0.247, p=0.007) and increased with central corneal thickness (r=0.208, p=0.022). Global retinal nerve fiber layer thickness positively correlated with choroidal thickness (r=0.354, p<0.001). Global retinal nerve fiber layer thickness (r=0.223, p=0.014) and choroidal thickness (r=0.272, p=0.003) increased with the spherical equivalent (D). Optical coherence tomography parameters showed a wide range of variability in children. Retinal nerve fiber layer thickness, central macular thickness, and choroidal thickness were found to be either inter-related or correlated with age, central corneal thickness, axial length, and refractive errors. Furthermore, manual measurements of choroidal thickness showed high interexaminer agreement. Because normative values for optical coherence tomography parameters differed in children, the measurements should be interpreted according to an age-appropriate database.

Repair of Irregularly Irregular Astigmatism by Transepithelial Phototherapeutic Keratectomy.

PubMed

Guglielmetti, Stefano; Kirton, Amy; Reinstein, Dan Z; Carp, Glenn I; Archer, Timothy J

2017-10-01

To evaluate the outcome of transepithelial phototherapeutic keratectomy (PTK) in the management of irregularly irregular astigmatism. This was a case series of two patients who underwent transepithelial PTK for irregularly irregular astigmatism. In the first case, the patient complained of diplopia due to corneal scarring caused by a metallic foreign body injury. The topography demonstrated irregularly irregular astigmatism with significant asymmetry in the inferotemporal to superonasal axis. In the second case, the patient complained of blurred vision and ghosting caused by significant central epithelial ingrowth through a buttonhole LASIK flap, which was causing a localized irregularity on topography. Due to the localized nature of the irregularities, a transepithelial PTK treatment was preferred to custom ablation given the degree of epithelial masking present. Transepithelial PTK was performed in both cases using the Schwind Amaris 500E excimer laser (Schwind eye-tech-solutions, Kleinostheim, Germany) and an 8-mm optical zone. The ablation depth was planned to reach the depth of the epithelium using a stepwise protocol, reviewing the pattern of the remaining epithelium and regularity of the stromal surface between each ablation. A marked improvement in the regularity of the topography was achieved in both cases, with only regular astigmatism remaining. Both patients reported a subjective improvement in quality of vision and the corrected distance visual acuity improved by one and two lines, respectively. Transepithelial PTK was effective in treating these cases of localized irregularly irregular astigmatism, achieving both objective and subjective improvement in vision. Compensatory epithelial remodeling over the irregularities enabled the transepithelial PTK approach to target the stromal surface irregularities. [J Refract Surg. 2017;33(10):714-719.]. Copyright 2017, SLACK Incorporated.

Comparison of laser in situ keratomileusis flaps created by 2 femtosecond lasers.

PubMed

Zheng, Yan; Zhou, Yuehua; Zhang, Jing; Liu, Qian; Zhai, Changbin; Wang, Yonghua

2015-03-01

To compare flap morphology created by the WaveLight FS200 femtosecond laser and the VisuMax femtosecond laser, assessing the uniformity, accuracy, and predictability of flap creation. A total of 400 eyes had corneal flaps created with the WaveLight FS200 femtosecond laser (200 eyes) or the VisuMax femtosecond laser (200 eyes). The desired flap thickness was 110 μm. At 1 week postoperatively, all eyes were evaluated with RTVue Fourier-domain optical coherence tomography. Dimensions of the flaps were tested for their regularity, uniformity, accuracy, and predictability comparison. One week after surgery, the central flap thickness and the mean flap thickness of the FS200 group were 105.4 ± 3.4 μm and 105.7 ± 2.6 μm, respectively. They were both thinner than those of the VisuMax group, which were 110.8 ± 3.9 μm and 111.3 ± 2.3 μm, respectively. The mean deviation between the achieved and attempted flap thickness of the FS200 group (5.2 ± 1.9 μm) was greater than that of the VisuMax group (3.2 ± 1.8 μm). Flap thickness measurements at 36 points in both groups were close to the intended thickness. Morphology of the flaps in the 0-, 45-, 90-, and 135-degree lines created by the FS200 femtosecond laser and VisuMax femtosecond laser were uniform and regular. Flap dimensions created by the WaveLight FS200 femtosecond laser and VisuMax femtosecond laser were uniform and regular. Although the flap thickness created by the FS200 was less than that created by the VisuMax, measurements of both femtosecond lasers were close to the intended thickness.

Anti-neovascular effect of chondrocyte-derived extracellular matrix on corneal alkaline burns in rabbits.

PubMed

Lee, Hye Sook; Lee, Ji Hyun; Kim, Chae Eun; Yang, Jae Wook

2014-06-01

We investigated the effect of a chondrocyte-derived extracellular matrix (CDECM) on experimental corneal alkaline burns in rabbits. Corneal neovascularization (NV) was induced by applying an 8-mm filter paper soaked in 1 N NaOH to the right central corneas of rabbits for 1 minute. Ten days later, the rabbits were randomly divided into three groups: the alkaline burn group, the CDECM transplantation group, and the human amniotic membrane (HAM) transplantation group. The left eyes were used as controls. CDECM and HAM were transplanted onto the corneal surface to completely cover the resected area and were subsequently sutured. On the 10th day after transplantation, the structural changes of the cornea were analyzed histologically. We examined the effects of CDECM on clinical NV features and on the expression of corneal NV markers. The alkaline burn produced significant NV and increased the corneal thickness. On day 10 after transplantation, the thickness, NV and opacity of the cornea were markedly decreased in the CDECM group (p < 0.001). However, the HAM transplantation group did not exhibit improvements in these clinical parameters, and there were no significant differences relative to the burn group. In addition, the use of CDECM improved the healing of the cornea following the alkaline burn by disrupting the corneal epithelial proliferation and reducing the fibrotic changes of the stroma. The hallmarks of NV were significantly induced in the subepithelium by the alkaline burn, and these levels were also suppressed by CDECM. The CDECM suppressed corneal NV by inhibiting nuclear factor-kappa B (NF-κB) activation by blocking the PKC and Akt signaling pathways. CDECM transplantation was markedly effective in healing alkali-burned corneas by modulating the translocation of NF-κB to the nucleus, thereby representing a promising material for the noninvasive treatment of ocular surface disease.

Small fiber neuropathy in women with fibromyalgia. An in vivo assessment using corneal confocal bio-microscopy.

PubMed

Ramírez, Manuel; Martínez-Martínez, Laura-Aline; Hernández-Quintela, Everardo; Velazco-Casapía, Jorge; Vargas, Angélica; Martínez-Lavín, Manuel

2015-10-01

A consistent line of investigation suggests that fibromyalgia is a neuropathic pain syndrome. This outlook has been recently reinforced by several controlled studies that describe decreased small nerve fiber density in skin biopsies of patients with fibromyalgia. The cornea receives the densest small fiber innervation of the body. Corneal confocal bio-microscopy is a new noninvasive method to evaluate small nerve fiber morphology. Our objective was to assess corneal small nerve fiber morphology in patients with fibromyalgia, and to associate corneal nerve microscopic features with neuropathic pain descriptors and other fibromyalgia symptoms. We studied 17 female patients with fibromyalgia and 17 age-matched healthy control subjects. All the participants completed different questionnaires regarding the symptoms of fibromyalgia, including a neuropathic pain survey. A central corneal thickness scan was obtained with a confocal microscope. Nerve measurements were made by a single ophthalmologist without knowledge of the clinical diagnosis. Stromal nerve thickness was defined as the mean value between the widest and the narrowest portion of each analyzed stromal nerve. Corneal sub-basal plexus nerve density was also assessed. Patients with fibromyalgia had stromal nerve thickness of 5.0 ± 1.0 µm (mean ± standard deviation) significantly different from that of control's values (6.1 ± 1.3) p = 0.01. Patients also had decreased sub-basal plexus nerve density per square millimeter (85 ± 29) vs. 107 ± 26 of controls p = 0.02. When controls and patients were grouped together, there was an association between stromal nerve slenderness and neuropathic pain descriptors (Fisher's exact test p = 0.007). Women suffering from fibromyalgia have thinner corneal stromal nerves and diminished sub-basal plexus nerve density when compared to healthy controls. Nerve scarcity is associated with neuropathic pain descriptors. Small fiber neuropathy may play a role in the pathogenesis of fibromyalgia pain. Corneal confocal microscopy could become a useful test in the study of patients with fibromyalgia. Copyright © 2015. Published by Elsevier Inc.

Peripheral corneal infiltrates associated with contact lens wear.

PubMed Central

Donshik, P C; Suchecki, J K; Ehlers, W H

1995-01-01

PURPOSE: A retrospective study was performed to review the clinical characteristics of peripheral corneal infiltrates in contact lens wearers. METHODS: The charts of all contact lens patients with peripheral corneal infiltrates 1.5 mm or less in size who presented to the office from 1987 to 1994 were reviewed. RESULTS: The epidemiological and clinical characteristics of peripheral corneal infiltrates associated with contact lens wear were reviewed in 52 patients (64 infiltrates). Forty-four patients presented with a single infiltrate, while the remaining 8 patients had multiple infiltrates. While there was no predilection for a specific quadrant of the cornea, when a subgroup of patients who wore extended wear lenses was analyzed, 19 of the 40 infiltrates were located in the superior quadrant. Forty percent of the patients were wearing disposable extended wear contact lenses, 21% were wearing conventional extended wear lenses, 33% were wearing conventional or frequent replacement/disposable daily wear contact lenses and 6% were wearing rigid gas permeable lenses. The majority of patients had minimal conjunctival inflammation, an anterior stromal cellular reaction and minimal anterior chamber activity. A subgroup of 16 patients had corneal cultures of their infiltrates. In this group, 8 of the 16 had positive cultures. All patients had a resolution of the infiltrates without complications and the majority were refitted to daily wear soft or rigid contact lenses. CONCLUSION: Peripheral corneal infiltrates in contact lens wearers appears to be more common in patients wearing extended wear soft contact lenses. While often considered "sterile" in the literature, a significant number have been shown to be culture-positive. The organisms that have been associated with peripheral infiltrates appear to be less "pathogenic" than those that have been reported to be associated with central corneal ulcer. However, it is probably advisable that patients with peripheral corneal ulcers secondary to contact lens wear should be initially treated with topical antibiotics. PMID:8719670

Interface fluid syndrome in human eye bank corneas after LASIK: causes and pathogenesis.

PubMed

Dawson, Daniel G; Schmack, Ingo; Holley, Glenn P; Waring, George O; Grossniklaus, Hans E; Edelhauser, Henry F

2007-10-01

To evaluate the effects of corneal edema on human donor corneas that had previous LASIK using a laboratory model with histologic and ultrastructural correlations. Experimental study. Thirty human eye bank corneas from 15 donors (mean age +/- standard deviation, 49.9+/-8.9 years) who had had previous LASIK surgery (2-8 years before death). The corneas were mounted in an artificial anterior chamber and the corneal endothelium was perfused for up to 5.0 hours with 0.9% saline solution (endothelial cell damage group) or BSS Plus at a pressure of 15 mmHg (control group), or BSS Plus at a pressure of 55 mmHg (high-pressure group). The corneas were evaluated by confocal and specular microscopy before, during, and at the end of the experimental period. Subsequently, the specimens were evaluated by light and electron microscopy. Corneal thickness, reflectivity, histology, and ultrastructure. Endothelial cell damage resulted in an increased (141.5+/-38.8 microm) total corneal thickness relative to controls (52.3+/-33.7 microm), whereas high pressure resulted in a decreased thickness (24.8+/-14.1 microm) relative to controls. This ultimately was due to swelling of the LASIK interface in both groups and swelling of the residual stromal bed (RSB) in the endothelial cell damage group or compression of the RSB and, possibly, the flap in the high-pressure group. A significant increase in corneal reflectivity at the LASIK interface occurred in both groups, primarily due to varying degrees of fluid accumulation and associated hydropic keratocyte degeneration, as well as increased corneal reflectivity in the RSB only in the endothelial cell damage group. After LASIK surgery, edematous corneas preferentially hydrate and swell in the paracentral and central interface wound, commonly resulting in a hazy corneal appearance primarily due to keratocyte hydropic degeneration. More severe corneal edema is characterized by the formation of an optically empty space corresponding to an interface fluid pocket. The spectrum of interface fluid syndrome can be described in 3 stages.

Corneal Thickness in Highlanders.

PubMed

Patyal, Sagarika; Arora, Amit; Yadav, Arun; Sharma, Vijay K

2017-03-01

Patyal, Sagarika, Amit Arora, Arun Yadav, and Vijay K. Sharma. Corneal thickness in highlanders. High Alt Med Biol. 18:56-60, 2017. Corneal thickness is an important parameter with diagnostic and therapeutic implications. Various studies have highlighted increase in corneal thickness in lowlanders on ascending to high altitude. However, there are no studies in the published literature pertaining to corneal thickness of the highlanders who are inhabitants of such altitudes. Hence, study was carried out with objective to determine the corneal thickness of highlanders living at heights of more than 11,000 feet and compare it with corneal thickness of lowlanders. The highlander participants of the study consisted of inhabitants of Ladakh region of India at an altitude of 11,000 feet or more and lowlander participants consisted of inhabitants at an altitude of 1500 feet. A total of 254 highlanders and 212 lowlanders participated. A mean of 25 measurements of central corneal thickness (CCT) of every participant was obtained for each eye using ultrasonic pachymeter. The mean age of the participants was 41.8 (15.9) and 47.7 (17.7) years among lowlanders and highlanders, respectively. The highlanders had 11.95 μm lower mean CCT reading compared to lowlanders after adjusting for age and sex (p value <0.001). There was no statistically significant difference in mean CCT readings of right eye and left eye in either lowlanders or highlanders. Age also had a significant effect after adjustment for location and gender (p = 0.001). CCT decreased by 0.31 μm with every year increase in the age. Gender had no statistically significant effect. This study found statistically significant difference in CCT measurements between highlanders and lowlanders. The thinner corneas of highlanders may have a bearing on diagnosis and treatment of glaucoma, refractive surgery, contact lens fitting implantation of Intacs, and astigmatic keratectomy done on such patients. The study also opens the scope of further research in the area.

Temporal and Spatial Flap Variability in Laser In-Situ Keratomileusis by Optical Coherence Tomography.

PubMed

Dawood, Yousif Farhan; Al Hassany, Usama; Issa, Ammar F

2017-01-01

To study changes in flap thickness made with two different microkeratome heads across different corneal locations using anterior segment optical coherence tomography (OCT). In this prospective, non-randomized, consecutive case series, subjects who had their laser in-situ keratomileusis (LASIK) flaps made using 90 μm (MSU90) or 130 μm (MSU130) disposable M2 microkeratome heads were examined using OCT. The measurements were performed at three locations (central and 2.5 mm to either side) at 1 day, 1 week, and 1 month postoperatively. The central flap thickness was 123 ± 15, 130 ± 14, and 127 ± 13 μm, respectively, at 1 day, 1 week, and 1 month postoperatively in the MSU90 group (41 eyes) and 142 ± 20, 147 ± 19, and 143 ± 15 μm, respectively, in the MSU130 group (47 eyes). At 1 month, peripheral flap thickness was 161 ± 17 and 159 ± 13 μm, respectively, at 2.5 mm to the right and left of corneal center in the MSU90 group. The corresponding figures were 170 ± 14 and 167 ± 13 μm, respectively, in the MSU130 group. There was a statistically significant difference between the two groups at all locations ( P < 0.001). No statistically significant change in flap thickness was detected in either group at any assessment time. There was a partial positive correlation (after controlling for preoperative manifest refractive spherical equivalent) between central flap thickness and preoperative ultrasound central pachymetry ( r = 0.739, P = 0.036) in the MSU90 group but not in the MSU130 group. Using OCT, changes in flap thickness were minimal in the first month after LASIK. Flap thickness correlated strongly with central corneal thickness if a 90 μm head was used.

Does lamellar surgery for keratoconus experience the popularity it deserves?

PubMed

Wisse, Robert P L; van den Hoven, Célinde M L; Van der Lelij, Allegonda

2014-08-01

To analyse developments in surgical treatment for keratoconus (KC) by assessing rates and types of corneal surgery from 2005 to 2010. The Dutch Transplantation Foundation supplied data on all keratoplasty procedures for KC performed from 2005 to 2010 in the Netherlands. Registration was carried out by the eyebank at allocation and by the surgeon at the time of surgery. The type of surgery was categorized as either a penetrating or a lamellar procedure. Five hundred and seventy-five anonymized records were received, with excellent data completion (99%). Patients undergoing penetrating surgery had on average a lower visual acuity, higher k-readings and were slightly older compared with the lamellar group. A previous corneal hydrops was recorded for 19.1% of patients. Regular penetrating keratoplasty decreased in popularity from 79.7% in 2005 to 43.7% in 2010, due to the increased rate of lamellar surgery (42.5% in 2010) and 'mushroom' penetrating keratoplasty (13.8% in 2010). When hydrops cases were excluded, popularity became equal (47.6% penetrating versus 52.4% lamellar surgery, in 2010). Lamellar surgery is gaining in popularity, although regular penetrating keratoplasty is still the more commonly performed procedure. Only when hydrops cases are excluded do transplant rates become comparable. © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

The effects of Rho-associated kinase inhibitor Y-27632 on primary human corneal endothelial cells propagated using a dual media approach.

PubMed

Peh, Gary S L; Adnan, Khadijah; George, Benjamin L; Ang, Heng-Pei; Seah, Xin-Yi; Tan, Donald T; Mehta, Jodhbir S

2015-03-16

The global shortage of donor corneas has garnered extensive interest in the development of graft alternatives suitable for endothelial keratoplasty using cultivated primary human corneal endothelial cells (CECs). We have recently described a dual media approach for the propagation of human CECs. In this work, we characterize the effects of a Rho-kinase inhibitor Y-27632 on the cultivation of CECs propagated using the dual media culture system. Seventy donor corneas deemed unsuitable for transplantation were procured for this study. We assessed the use of Y-27632 for its effect at each stage of the cell culture process, specifically for cell attachment, cell proliferation, and during both regular passaging and cryopreservation. Lastly, comparison of donor-matched CEC-cultures expanded with or without Y-27632 was also performed. Our results showed that Y-27632 significantly improved the attachment and proliferation of primary CECs. A non-significant pro-survival effect was detected during regular cellular passage when CECs were pre-treated with Y-27632, an effect that became more evident during cryopreservation. Our study showed that the inclusion of Y-27632 was beneficial for the propagation of primary CECs expanded via the dual media approach, and was able to increase overall cell yield by between 1.96 to 3.36 fold.

[Corneal subbasal nerve density changes after laser in situ keratomileusis with mechanical microkeratome and femtosecond laser].

PubMed

Hu, Liang; Xie, Wenjia; Tang, Lei; Chen, Jia; Zhang, Dong; Yu, Peng; Qu, Jia

2015-01-01

To compare the corneal subbasal nerve density (SND) changes after laser in situ keratomileusis (LASIK) with a microkeratome and a femtosecond laser. Prospective clinical study. Sixty eyes of thirty myopes were included. Fifteen patients (30 eyes) underwent LASIK with the Moria II microkeratome, and the other 15 patients (30 eyes) with the 60 k Hz IntraLase femtosecond laser. Central, temporal and nasal corneal SNDs were measured by confocal microscopy and compared before surgery, 1 month, and 3 months after surgery. Analysis of variance and t test were used for comparing the differences between different time points and two groups. Preoperatively and 1 month, 3 months postoperatively, the SNDs were (16 728.30 ± 4 300.30), (1 875.42 ± 300.50) and (1 701.55 ± 194.11) µm/mm(2) in the central cornea, (11 379.70 ± 1 833.92), (1 341.20 ± 288.68) and (1 860.87 ± 147.60) µm/mm(2) in the temporal cornea, and (8 506.79 ± 662.83), (7 428.96 ± 712.99) and (8 044.32 ± 1 077.54) µm/mm(2) in the nasal cornea, respectively, in the microkeratome group, and (16 351.59 ± 3 503.88), (1 859.38 ± 452.93) and (2 043.67 ± 377.76) in the central cornea, (12 328.22 ± 2 007.43), (1 483.85 ± 371.28) and (2 126.31 ± 279.87) µm/mm(2) in the temporal cornea, and (8 347.91 ± 789.44), (1 475.53 ± 293.98) and (2 022.10 ± 282.89) µm/mm(2) in the nasal cornea, respectively, in the femtosecond laser group. The SNDs at three positions all decreased significantly at each time point postoperatively compared to the baseline values in both groups (1 and 3 months in the microkeratome group: central t = 18.981 and 18.912, temporal t = 30.121 and 27.921, and nasal t = 6.456 and 2.126; in the femtosecond laser group: central t = 22.667 and 22.379, temporal t = 29.000 and 28.376, and nasal t = 46.329 and 41.751; all P < 0.01, except 3 months at the nasal in the microkeratome group, P = 0.042). The nasal SND increased significantly from month 1 to month 3 (t = -3.921, P < 0.01) in the microkeratome group, and the temporal and nasal SNDs both increased significantly from month 1 to month 3 (t = -9.629 and -6.645, both P < 0.01) in the femtosecond group. There were no significant differences in the central SND between the two groups (F = 0.002, P = 0.96). Significant differences were found in the nasal SND between the groups at 1 month and 3 months (t = 42.281 and 29.608, both P < 0.01), and in the temporal SND at 3 months after surgery (t = -4.595, P < 0.01). Peripheral corneal nerve recovery occurred at 1 month after LASIK surgery. Patients with a femtosecond laser showed better corneal regeneration than those with a microkeratome.

Changes in the cornea related to sickle cell disease: a pilot investigation.

PubMed

Coşkun, Mesut; İlhan, Özgür; İlhan, Nilüfer; Tuzcu, Esra Ayhan; Daglioğlu, Mutlu Cihan; Kahraman, Hilal; Elbeyli, Ahmet; Yarbağ, Abdulhekim; Helvaci, Mehmet Rami

2015-01-01

To investigate corneal structural changes (central corneal thickness, endothelial cell count, and cellular morphology) in patients with sickle cell disease (SCD). This prospective study included 56 patients with SCD and 50 age- and sex-matched healthy subjects without any eye disease aside from refractive errors. Endothelial cell density (ECD), percentage of hexagonality, and the coefficient of variation in cell size (CV) were measured using noncontact specular microscopy, and central corneal thickness (CCT) was measured by pachymetry. The mean CCT value was 509.6 ± 20.7 μm in the study group and 520.8 ± 23.6 μm in the control group. The mean ECD, CV, and percentage of hexagonality values in the study group were 2712 ± 335 cells/mm², 34.5 ± 5.3%, and 57.2 ± 6.6%, respectively, and 3030 ± 247 cells/mm², 31.6 ± 5.0%, and 60.4 ± 6.9% in the control group, respectively. Endothelial cell density (p = 0.001), CCT (p = 0.011), CV (p = 0.005), and percentage of hexagonality values (p = 0.018) were significantly different between the study and control groups. The results of the current study indicate that patients with SCD had considerable morphologic changes in the structure of the cornea when compared to healthy subjects.

Biometric and structural ocular manifestations of Marfan syndrome.

PubMed

Gehle, Petra; Goergen, Barbara; Pilger, Daniel; Ruokonen, Peter; Robinson, Peter N; Salchow, Daniel J

2017-01-01

To study biometric and structural ocular manifestations of Marfan syndrome (MFS). Observational, retrospective, comparative cohort study in a tertiary referral center on 285 MFS patients and 267 controls. Structural and biometric ocular characteristic were compared. MFS eyes were longer (axial length 24.25 ± 1.74 mm versus 23.89 ± 1.31 mm, p < 0.001) and had a flatter cornea than control eyes (mean keratometry 41.78 ± 1.80 diopters (D) versus 43.05 ± 1.51 D, p < 0.001). Corneal astigmatism was greater and the central cornea was thinner in MFS eyes (530.14 ± 41.31 μm versus 547.02 ± 39.18 μm, p < 0.001). MFS eyes were more myopic than control eyes (spherical equivalent -2.16 ± 3.75 D versus -1.17 ± 2.58 D, p < 0.001). Visual acuity was reduced (0.13 ± 0.25 logMAR versus 0.05 ± 0.18 logMAR, p < 0.001) and intraocular pressure was lower in MFS eyes (14.6 ± 3.4 mmHg versus 15.1 ± 3.2 mmHg, p = 0.01). Iris transillumination defects (ITD) were significantly more common in MFS eyes (odds ratio for MFS in the presence of ITD, 3.7). Ectopia lentis (EL) was only present in MFS eyes (33.4%). History of retinal detachment was significantly more common in MFS eyes. Glaucoma was equally common in both groups. ITD and EL are most characteristic findings in MFS. ITD and corneal curvature should be studied as diagnostic criteria for MFS. Visual acuity is reduced in MFS. MFS patients need regular eye exams to identify serious ocular complications.

Biometric and structural ocular manifestations of Marfan syndrome

PubMed Central

Gehle, Petra; Goergen, Barbara; Pilger, Daniel; Ruokonen, Peter; Robinson, Peter N.

2017-01-01

Background To study biometric and structural ocular manifestations of Marfan syndrome (MFS). Methods Observational, retrospective, comparative cohort study in a tertiary referral center on 285 MFS patients and 267 controls. Structural and biometric ocular characteristic were compared. Results MFS eyes were longer (axial length 24.25 ± 1.74 mm versus 23.89 ± 1.31 mm, p < 0.001) and had a flatter cornea than control eyes (mean keratometry 41.78 ± 1.80 diopters (D) versus 43.05 ± 1.51 D, p < 0.001). Corneal astigmatism was greater and the central cornea was thinner in MFS eyes (530.14 ± 41.31 μm versus 547.02 ± 39.18 μm, p < 0.001). MFS eyes were more myopic than control eyes (spherical equivalent -2.16 ± 3.75 D versus -1.17 ± 2.58 D, p < 0.001). Visual acuity was reduced (0.13 ± 0.25 logMAR versus 0.05 ± 0.18 logMAR, p < 0.001) and intraocular pressure was lower in MFS eyes (14.6 ± 3.4 mmHg versus 15.1 ± 3.2 mmHg, p = 0.01). Iris transillumination defects (ITD) were significantly more common in MFS eyes (odds ratio for MFS in the presence of ITD, 3.7). Ectopia lentis (EL) was only present in MFS eyes (33.4%). History of retinal detachment was significantly more common in MFS eyes. Glaucoma was equally common in both groups. Conclusions ITD and EL are most characteristic findings in MFS. ITD and corneal curvature should be studied as diagnostic criteria for MFS. Visual acuity is reduced in MFS. MFS patients need regular eye exams to identify serious ocular complications. PMID:28931008

A Two-Piece Microkeratome-Assisted Mushroom Keratoplasty Improves the Outcomes and Survival of Grafts Performed in Eyes with Diseased Stroma and Healthy Endothelium (An American Ophthalmological Society Thesis)

PubMed Central

Busin, Massimo; Madi, Silvana; Scorcia, Vincenzo; Santorum, Paolo; Nahum, Yoav

2015-01-01

Purpose: To test the hypothesis that a new microkeratome-assisted penetrating keratoplasty (PK) technique employing transplantation of a two-piece mushroom-shaped graft may result in better visual outcomes and graft survival rates than those of conventional PK. Methods: Retrospective chart review of 96 eyes at low risk and 76 eyes at high risk for immunologic rejection (all with full-thickness central corneal opacity and otherwise healthy endothelium) undergoing mushroom PK between 2004 and 2012 at our Institution. Outcome measures were best-corrected visual acuity (BCVA), refraction, corneal topography, endothelial cell density, graft rejection, and survival probability. Results: Five years postoperatively, BCVA of 20/40 and 20/20 was recorded in 100% and over 50% of eyes, respectively. Mean spherical equivalent of refractive error did not vary significantly over a 5-year period; astigmatism averaged always below 4 diopters, with no statistically significant change over time, and was of the regular type in over 90% of eyes. Endothelial cell density decreased to about 40% of the eye bank count 2 years after mushroom PK and did not change significantly thereafter. Five years postoperatively, probabilities of graft immunologic rejection and graft survival were below 5% and above 95%, respectively. There was no statistically significant difference in endothelial cell loss, graft rejection, and survival probability between low-risk and high-risk subgroups. Conclusions: Refractive and visual outcomes of mushroom PK compare favorably with those of conventional full-thickness keratoplasty. In eyes at high risk for immunologic rejection, mushroom PK provides a considerably higher probability of graft survival than conventional PK. PMID:26538771

Correlation between corneal thickness and optic disc morphology in normal tension glaucoma using modern technical analysis.

PubMed

Coman, Laurenţiu; Costescu, Monica; Alecu, Mihail; Coman, Oana Andreia

2014-01-01

The purpose of this study was to evaluate the relationship between central corneal thickness (CCT) and optic disc morphology in normal tension glaucoma (NTG). Patients with NTG underwent eye examination, optic disc imaging with Heildelberg Retina Tomograph II (HRT II) and ultrasound corneal pachymetry. The morphological parameters of the optic discs were used to classify the eyes into four groups: generalized enlargement (GE) type, myopic glaucomatous (MY) type, focal ischemic (FI) type and senile sclerotic (SS) type. A correlation between CCT and optic disc morphology obtained by HRT II was calculated. Multiple comparison and post hoc tests were performed in order to determine the significance of the differences between the four groups. The strongest correlation was between CCT and the parameters of optic disc imaging obtained at HRT II in the GE type of optic disc.

Anterior segment dysgenesis (Peters' anomaly) in two snow leopard (Panthera uncia) cubs.

PubMed

Hamoudi, Hassan; Rudnick, Jens-Christian; Prause, Jan U; Tauscher, Kerstin; Breithaupt, Angele; Teifke, Jens P; Heegaard, Steffen

2013-07-01

Two sibling snow leopards, a male and a female, with bilateral anterior segment dysgenesis (ASD), are reported. Both snow leopards also had colobomas of both upper eyelids. All eyes exhibited a central corneal opacity associated with a defect in posterior corneal stroma, endothelium and Descemet's membrane. Iris strands were present attached to the termination of Descemet's membrane and to the periphery of the posterior corneal defect. The iris was hypoplastic, and cataract was present in all four eyes. The left eye of the female was microphthalmic, with no trabecular meshwork and with persistent remnant of the hyaloid artery. The male had hydrocephalus and thus some of the features of Peters' plus syndrome (Peters' anomaly in addition to systemic malformations). The histological findings in the eyes of these snow leopard siblings are identical with those described in humans with Peters' anomaly. © 2012 American College of Veterinary Ophthalmologists.

Development of an algorithm for corneal reshaping with a scanning laser beam

NASA Astrophysics Data System (ADS)

Shen, Jin-Hui; Söderberg, Per; Matsui, Takaaki; Manns, Fabrice; Parel, Jean-Marie

1995-07-01

The corneal-ablation rate, the beam-intensity distribution, and the initial and the desired corneal topographies are used to calculate a spatial distribution map of laser pulses. The optimal values of the parameters are determined with a computer model, for a system that produces 213-nm radiation with a Gaussian beam-intensity distribution and a peak radiant exposure of 400 mJ/cm2. The model shows that with a beam diameter of 0.5 mm, an overlap of 80%, and a 5-mm treatment zone, the roughness is less than 6% of the central ablation depth, the refractive error after correction is less than 0.1 D for corrections of myopia of 1, 3, and 6 D and less than 0.4 D for a correction of myopia of 10 D, and the number of pulses per diopter of

Changes in corneal endothelial cell density and the cumulative risk of corneal decompensation after Ahmed glaucoma valve implantation.

PubMed

Kim, Kyoung Nam; Lee, Sung Bok; Lee, Yeon Hee; Lee, Jong Joo; Lim, Hyung Bin; Kim, Chang-Sik

2016-07-01

To evaluate changes in the corneal endothelial cell density (ECD) and corneal decompensation following Ahmed glaucoma valve (AGV) implantation. This study was retrospective and observational case series. Patients with refractory glaucoma who underwent AGV implantation and were followed >5 years were consecutively enrolled. We reviewed the medical records, including the results of central corneal specular microscopy. Of the 127 enrolled patients, the annual change in ECD (%) was determined using linear regression for 72 eyes evaluated at least four times using serial specular microscopic examination and compared with 31 control eyes (fellow glaucomatous eyes under medical treatment). The main outcome measures were cumulative risk of corneal decompensation and differences in the ECD loss rates between subjects and controls. The mean follow-up after AGV implantation was 43.1 months. There were no cases of postoperative tube-corneal touch. The cumulative risk of corneal decompensation was 3.3%, 5 years after AGV implantation. There was a more rapid loss of ECD in the 72 subject eyes compared with the 31 controls (-7.0% and -0.1%/year, respectively; p<0.001). However, the rate of loss decreased over time and statistical significance compared with control eyes disappeared after 2 years postoperatively: -10.7% from baseline to 1 year (p<0.01), -7.0% from 1 year to 2 years (p=0.037), -4.2% from 2 years to 3 years (p=0.230) and -2.7% from 3 years to the final follow-up (p=0.111). In case of uncomplicated AGV implantation, the cumulative risk of corneal decompensation was 3.3%, 5 years after the operation. The ECD loss was statistically greater in eyes with AGV than in control eyes without AGV, but the difference was significant only up to 2 years post surgery. 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/.

Resolvin D1 promotes corneal epithelial wound healing and restoration of mechanical sensation in diabetic mice.

PubMed

Zhang, Zhenzhen; Hu, Xiaoli; Qi, Xia; Di, Guohu; Zhang, Yangyang; Wang, Qian; Zhou, Qingjun

2018-01-01

To investigate the effect and mechanism of proresolving lipid mediator resolvin D1 (RvD1) on the corneal epithelium and the restoration of mechanical sensation in diabetic mice. Type 1 diabetes was induced in mice with intraperitoneal streptozocin injections. The healthy and diabetic mice underwent removal of the central corneal epithelium, and then 100 ng/ml RvD1 or its formyl peptide receptor 2 (FPR2) antagonist WRW4 was used to treat the diabetic mice. Regeneration of the corneal epithelium and nerves was observed with sodium fluorescein staining and whole-mount anti-β3-tubulin fluorescence staining. The inflammatory response level was measured with hematoxylin and eosin staining (inflammatory cell infiltration), enzyme-linked immunosorbent assay (tumor necrosis factor alpha and interleukin-1 beta content), myeloperoxidase activity, and fluorescence staining (macrophage content). The reactive oxygen species (ROS) and glutathione (GSH) levels were examined with incubation with fluorescent probes, and oxidative stress-related protein expression levels were evaluated with fluorescence staining and western blotting. Topical application of RvD1 promoted regeneration of the corneal epithelium in diabetic mice, accompanied by the reactivation of signaling and inflammation resolution related to regeneration of the epithelium. Furthermore, RvD1 directly attenuated the accumulation of ROS and nicotinamide adenine dinucleotide phosphate oxidase 2/4 expression, while RvD1 enhanced GSH synthesis and reactivated the Nrf2-ARE signaling pathway that was impaired in the corneal epithelium in the diabetic mice. More interestingly, topical application of RvD1 promoted regeneration of corneal nerves and completely restored impaired mechanical sensitivity of the cornea in diabetic mice. In addition, the promotion of corneal epithelial wound healing by RvD1 in diabetic mice was abolished by its FPR2 antagonist WRW4. Topical application of RvD1 promotes corneal epithelial wound healing and the restoration of mechanical sensation in diabetic mice, which may be related to the lipid mediator's regulation of inflammation resolution, the reactivation of regenerative signaling in the epithelium, and the attenuation of oxidative stress.

IL-20 promotes epithelial healing of the injured mouse cornea.

PubMed

Zhang, Wanyu; Magadi, Sri; Li, Zhijie; Smith, C Wayne; Burns, Alan R

2017-01-01

After corneal epithelial injury, the ensuing inflammatory response is necessary for efficient wound healing. While beneficial healing effects are attributed to recruited neutrophils and platelets, dysregulated inflammation (too little or too much) is associated with impaired wound healing. The purpose of this study was to use an established C57BL/6J mouse model of corneal injury to evaluate the potential modulatory role of interleukin-20 (IL-20) on the inflammatory and healing responses to epithelial wounding. In the uninjured cornea, immunofluorescence staining for IL-20 and its receptor, IL-20RA, was observed on basal epithelial cells at the limbus. After a 2 mm central epithelial abrasion, IL-20 staining was also observed in stromal keratocytes and ELISA studies showed a significant increase (nearly 3-fold) in IL-20 expression. Injured corneas healed more slowly when treated with a topical application of a neutralizing anti-IL-20 antibody. While corneal epithelial cell division and epithelial nerve recovery measured at 24 h post-injury were reduced compared to controls, neutrophil influx into the cornea was increased. In contrast, topical application of recombinant IL-20 (rIL-20) decreased corneal inflammation as evidenced by reductions in limbal vessel dilatation, platelet extravasation, neutrophil recruitment and CXCL1 expression. In wild type mice, topical rIL-20 had a limited effect on corneal wound healing and resulted in only a slight increase in epithelial cell division and epithelial nerve recovery; the rate of wound closure was unaffected. To clarify the effect of IL-20 on corneal wound healing, rIL-20 was topically applied to neutropenic wild type (WT) mice and mutant mice (ɣδ T cell deficient mice and CD11a deficient mice), all of which have well characterized reductions in neutrophil recruitment and delayed wound healing after corneal injury. In each case, rIL-20 restored corneal wound healing to baseline levels while neutrophil recruitment remained low. Thus, it appears that IL-20 plays a beneficial and direct role in corneal wound healing while negatively regulating neutrophil and platelet infiltration. Copyright © 2016 Elsevier Ltd. All rights reserved.

CD147 Required for Corneal Endothelial Lactate Transport

PubMed Central

Li, Shimin; Nguyen, Tracy T.; Bonanno, Joseph A.

2014-01-01

Purpose. CD147/basigin is a chaperone for lactate:H+ cotransporters (monocarboxylate transporters) MCT1 and MCT4. We tested the hypothesis that MCT1 and -4 in corneal endothelium contribute to lactate efflux from stroma to anterior chamber and that silencing CD147 expression would cause corneal edema. Methods. CD147 was silenced via small interfering ribonucleic acid (siRNA) transfection of rabbit corneas ex vivo and anterior chamber lenti-small hairpin RNA (shRNA) pseudovirus in vivo. CD147 and MCT expression was examined by Western blot, RT-PCR, and immunofluorescence. Functional effects were examined by measuring lactate-induced cell acidification, corneal lactate efflux, [lactate], central cornea thickness (CCT), and Azopt (a carbonic anhydrase inhibitor) sensitivity. Results. In ex vivo corneas, 100 nM CD147 siRNA reduced CD147, MCT1, and MCT4 expression by 85%, 79%, and 73%, respectively, while MCT2 expression was unaffected. CD147 siRNA decreased lactate efflux from 3.9 ± 0.81 to 1.5 ± 0.37 nmol/min, increased corneal [lactate] from 19.28 ± 7.15 to 56.73 ± 8.97 nmol/mg, acidified endothelial cells (pHi = 6.83 ± 0.07 vs. 7.19 ± 0.09 in control), and slowed basolateral lactate-induced acidification from 0.0034 ± 0.0005 to 0.0012 ± 0.0005 pH/s, whereas apical acidification was unchanged. In vivo, CD147 shRNA increased CCT by 28.1 ± 0.9 μm at 28 days; Azopt increased CCT to 24.4 ± 3.12 vs. 12.0 ± 0.48 μm in control, and corneal [lactate] was 47.63 ± 6.29 nmol/mg in shCD147 corneas and 17.82 ± 4.93 nmol/mg in paired controls. Conclusions. CD147 is required for the expression of MCT1 and MCT4 in the corneal endothelium. Silencing CD147 slows lactate efflux, resulting in stromal lactate accumulation and corneal edema, consistent with lactate efflux as a significant component of the corneal endothelial pump. PMID:24970254

CD147 required for corneal endothelial lactate transport.

PubMed

Li, Shimin; Nguyen, Tracy T; Bonanno, Joseph A

2014-06-26

CD147/basigin is a chaperone for lactate:H(+) cotransporters (monocarboxylate transporters) MCT1 and MCT4. We tested the hypothesis that MCT1 and -4 in corneal endothelium contribute to lactate efflux from stroma to anterior chamber and that silencing CD147 expression would cause corneal edema. CD147 was silenced via small interfering ribonucleic acid (siRNA) transfection of rabbit corneas ex vivo and anterior chamber lenti-small hairpin RNA (shRNA) pseudovirus in vivo. CD147 and MCT expression was examined by Western blot, RT-PCR, and immunofluorescence. Functional effects were examined by measuring lactate-induced cell acidification, corneal lactate efflux, [lactate], central cornea thickness (CCT), and Azopt (a carbonic anhydrase inhibitor) sensitivity. In ex vivo corneas, 100 nM CD147 siRNA reduced CD147, MCT1, and MCT4 expression by 85%, 79%, and 73%, respectively, while MCT2 expression was unaffected. CD147 siRNA decreased lactate efflux from 3.9 ± 0.81 to 1.5 ± 0.37 nmol/min, increased corneal [lactate] from 19.28 ± 7.15 to 56.73 ± 8.97 nmol/mg, acidified endothelial cells (pHi = 6.83 ± 0.07 vs. 7.19 ± 0.09 in control), and slowed basolateral lactate-induced acidification from 0.0034 ± 0.0005 to 0.0012 ± 0.0005 pH/s, whereas apical acidification was unchanged. In vivo, CD147 shRNA increased CCT by 28.1 ± 0.9 μm at 28 days; Azopt increased CCT to 24.4 ± 3.12 vs. 12.0 ± 0.48 μm in control, and corneal [lactate] was 47.63 ± 6.29 nmol/mg in shCD147 corneas and 17.82 ± 4.93 nmol/mg in paired controls. CD147 is required for the expression of MCT1 and MCT4 in the corneal endothelium. Silencing CD147 slows lactate efflux, resulting in stromal lactate accumulation and corneal edema, consistent with lactate efflux as a significant component of the corneal endothelial pump. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

An assessment of regional differences in corneal thickness in normal human eyes, using the Orbscan II or ultrasound pachymetry.

PubMed

Doughty, Michael J; Jonuscheit, Sven

2007-04-01

In recent years, there has been increasing interest in the characteristics of the peripheral cornea close to the limbus, in both tonometry measures and refractive surgery, but there is relatively little information on these characteristics as provided by modern day pachymetry instruments such as the Orbscan (Bausch & Lomb, Rochester, New York). The current study was therefore undertaken to assess the corneal thickness profile along the horizontal meridian by this scanning slit light method, comparing the data with that obtained with an ultrasound pachymeter. Noncontact specular microscopy was first performed on 17 adults (aged between 20 and 64 years) to check that the corneas were normal. Then, 3 assessments of the corneal thickness profile across the horizontal meridian were taken using the Orbscan II, and both the regional map data (7-mm-diameter measurement ring, 1-mm sample zones) and the point data from the numerical pachymetry output were used to extract data at specific locations nominally 0.5 mm apart. Ultrasound pachymetry (under topical anesthesia with benoxinate 0.4%) was then used to obtain thickness values at central, mid-peripheral (2.75 mm), and peripheral locations close to the limbus (4.5 mm). Specular microscopy yielded mean thickness of 0.529 +/- 0.032 mm, whereas single-point Orbscan readings at the geometric center of the cornea averaged 0.579 +/- 0.037 mm. Orbscan readings around the 7-mm-diameter measurement zone along the horizontal meridian averaged 0.681 +/- 0.034 mm (i.e., were 0.101 mm or 17.6% greater; P < 0.001). Mid-peripheral readings taken from the numerical maps at 2.5 to 3.0 mm averaged 0.645 mm (or 11% higher than central point readings), whereas peripheral readings between 4.0 and 4.5 mm averaged 0.727 mm (i.e., 26% higher than central point values). In marked contrast, ultrasound readings in the mid-periphery (2.75 mm) averaged just 0.553 mm (or 5.5% greater than the central corneal thickness [CCT]) and just 0.612 mm (i.e., 16.6% higher) in the periphery (4.5 mm). CCT profiles generated from the Orbscan numerical output across the horizontal meridian showed a predictable progressive increase in thickness from the center to the 4.5-mm location on both the temporal and nasal side. The mean differences between the Orbscan II and ultrasound pachymetry measures were thus not constant across the cornea. Without correction, these differences were close to 0.05 mm at the center but more than 0.100 mm at the peripheral sites, and proportional differences persisted after application of the default acoustic factor of 0.92 for the Orbscan readings. Orbscan II and ultrasound pachymetry measures generate a rather different profile for corneal thickness. The data from the 2 techniques should be considered as reporting different characteristics, rather than attempts being made to align Orbscan measurements to those of the ultrasound method. A single acoustic correction factor cannot be logically applied to all corneal thickness measures made with an Orbscan II.

The Steroids for Corneal Ulcers Trial

PubMed Central

Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V.; Ray, Kathryn J.; Hong, Kevin C.; Oldenburg, Catherine E.; Lee, Salena M.; Zegans, Michael E.; McLeod, Stephen D.; Lietman, Thomas M.; Acharya, Nisha R.

2013-01-01

Objectives To provide comprehensive trial methods and baseline data for the Steroids for Corneal Ulcers Trial and to present epidemiological characteristics such as risk factors, causative organisms, and ulcer severity. Methods Baseline data from a 1:1 randomized, placebo-controlled, double-masked clinical trial comparing prednisolone phosphate, 1%, with placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and had been taking moxifloxacin for 48 hours. The primary outcome for the trial is best spectacle-corrected visual acuity at 3 months from enrollment. This report provides comprehensive baseline data, including best spectacle-corrected visual acuity, infiltrate size, microbio-logical results, and patient demographics, for patients enrolled in the trial. Results Of 500 patients enrolled, 97% were in India. Two hundred twenty patients (44%) were agricultural workers. Median baseline visual acuity was 0.84 logMAR (Snellen, 20/125) (interquartile range, 0.36-1.7; Snellen, 20/50 to counting fingers). Baseline visual acuity was not significantly different between the United States and India. Ulcers in India had larger infiltrate/scar sizes (P=.04) and deeper infiltrates (P=.04) and were more likely to be localized centrally (P=.002) than ulcers enrolled in the United States. Gram-positive bacteria were the most common organisms isolated from the ulcers (n=366, 72%). Conclusions The Steroids for Corneal Ulcers Trial will compare the use of a topical corticosteroid with placebo as adjunctive therapy for bacterial corneal ulcers. Patients enrolled in this trial had diverse ulcer severity and on average significantly reduced visual acuity at presentation. PMID:21987581

The steroids for corneal ulcers trial: study design and baseline characteristics.

PubMed

Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V; Ray, Kathryn J; Hong, Kevin C; Oldenburg, Catherine E; Lee, Salena M; Zegans, Michael E; McLeod, Stephen D; Lietman, Thomas M; Acharya, Nisha R

2012-02-01

To provide comprehensive trial methods and baseline data for the Steroids for Corneal Ulcers Trial and to present epidemiological characteristics such as risk factors, causative organisms, and ulcer severity. Baseline data from a 1:1 randomized, placebo-controlled, double-masked clinical trial comparing prednisolone phosphate, 1%, with placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and had been taking moxifloxacin for 48 hours. The primary outcome for the trial is best spectacle-corrected visual acuity at 3 months from enrollment. This report provides comprehensive baseline data, including best spectacle-corrected visual acuity, infiltrate size, microbiological results, and patient demographics, for patients enrolled in the trial. Of 500 patients enrolled, 97% were in India. Two hundred twenty patients (44%) were agricultural workers. Median baseline visual acuity was 0.84 logMAR (Snellen, 20/125) (interquartile range, 0.36-1.7; Snellen, 20/50 to counting fingers). Baseline visual acuity was not significantly different between the United States and India. Ulcers in India had larger infiltrate/scar sizes (P = .04) and deeper infiltrates (P = .04) and were more likely to be localized centrally (P = .002) than ulcers enrolled in the United States. Gram-positive bacteria were the most common organisms isolated from the ulcers (n = 366, 72%). The Steroids for Corneal Ulcers Trial will compare the use of a topical corticosteroid with placebo as adjunctive therapy for bacterial corneal ulcers. Patients enrolled in this trial had diverse ulcer severity and on average significantly reduced visual acuity at presentation. clinicaltrials.gov Identifier: NCT00324168.

Intraocular lens bioactivity tested using rabbit corneal tissue cultures.

PubMed

Linnola, R J; Salonen, J I; Happonen, R P

1999-11-01

To evaluate the effects of different intraocular lens (IOL) materials on epithelial cell growth to test the sandwich theory; i.e., a bioactivity-based explanation of posterior capsule opacification (PCO) after cataract surgery. Central Hospital, Vaasa, and Institute of Dentistry and Turku Center for Biomaterials, University of Turku, Finland. Rabbit corneal tissue cultures were set up on poly(methyl methacrylate) (PMMA), heparin-surface-modified (HSM) PMMA, silicone, acrylate, and hydrogel IOLs for 1 week. The tissue consisted of intact epithelium and half the thickness of the corneal stroma, which was placed against the IOL. The growth of the epithelium was examined by light microscopy to evaluate the attachment of the corneal explant to the IOL surface. All tissue samples grew well under the culture conditions. When grown on PMMA, HSM PMMA, silicone, and hydrogel, the tissue did not attach to the IOL or the epithelium grew around the explant, suggesting that the attachment of the stroma to the IOL was poor or nonexistent. Some explants on acrylate IOLs attached directly to the IOL surface with no epithelial ingrowth between the stroma and the IOL. This tissue culture method can be used to examine the behavior of corneal tissue in contact with different IOL materials. The results suggest that the acrylate IOL may have bioactive properties. This, with the lens optic's square edge, may hinder lens epithelial cell proliferation and thus prevent PCO.

Association of smoking and other risk factors with Fuchs' endothelial corneal dystrophy severity and corneal thickness.

PubMed

Zhang, Xiaolin; Igo, Robert P; Fondran, Jeremy; Mootha, V Vinod; Oliva, Matt; Hammersmith, Kristin; Sugar, Alan; Lass, Jonathan H; Iyengar, Sudha K

2013-08-27

We investigated effects of smoking and other risk factors on the development of advanced Fuchs' endothelial corneal dystrophy (FECD) and on central corneal thickness (CCT). Eyes from Caucasian probands, affected and unaffected family members, and unrelated controls matched for age from the FECD Genetics Multi-Center Study (n = 2044 subjects) were examined. Univariate and multivariate models, adjusted for family correlations, were used to determine the effect of smoking, sex, diabetes, and age on FECD case/control status and CCT. In a multivariate model, sex and smoking were associated significantly with advanced FECD (grades 4-6) development (P = 0.016 and P = 0.047, respectively). Female sex increased odds by 34%. Smoking increased odds by 30%. In a multivariate model, diabetes was associated with an increase of 9.1 μm in average CCT (P = 0.021). Female sex was associated significantly with a decrease in average CCT by 6.9 μm (P = 0.015). Smoking had no significant effect on CCT in any model. As shown previously, advanced FECD was associated with large increases in CCT (31.4-94.2 μm). Smoking was associated with an increased risk of advanced FECD and self-reported diabetes was associated with increased CCT. Further study of the impact of smoking and diabetes on FECD development and changes in corneal thickness is warranted.

Normal and keratoconic corneal epithelial thickness mapping using Fourier-domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Li, Yan; Tan, Ou; Huang, David

2011-03-01

The detection of early-stage keratoconus is one of the most important safety issues in screening candidates for corneal refractive surgeries. We propose to use epithelial thickness maps to assist the diagnosis of keratoconus. The corneal epithelial thickness in normal and keratoconic eyes was mapped with optical coherence tomography (OCT). A Fourier-domain OCT system capable of acquiring 26,000 axial-scans per second was used. It has an axial resolution of 5μm in cornea. A pachymetry scan pattern (8 radials, 1024 axial-scans each, 6mm diameter, repeat 3 times) centered at the pupil center was used to image the cornea. The 3 repeated radial scans on each meridian were registered and averaged. Then the anterior corneal, posterior corneal and epithelial boundaries were segmented automatically with a computer algorithm by increased signal intensity at corresponding boundaries. The epithelial thickness map was generated by interpolating epithelial thickness profile calculated from each meridian. Normal and keratoconic eyes (24 eyes each) were scanned 3 times. The central epithelial thickness in normal eyes was thicker than those of keratoconic eyes (mean difference 2.1 μm, t-test p=0.05). The epithelium was thinner superiorly than inferiorly in normal eyes (mean difference -1.4+/-1.1μm, p<0.001) while thicker superiorly than inferiorly in keratoconic eyes (2.0+/-4.1 μm, p=0.02).

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.

Surface Wave Elastometry of the Cornea in Porcine and Human Donor Eyes

PubMed Central

Dupps, William J.; Netto, Marcelo V.; Herekar, Satish; Krueger, Ronald R.

2007-01-01

PURPOSE To introduce a nondestructive technique for characterization of corneal stiffness, determine measurement precision, and investigate comparative stiffness values along central, radial, and circumferential vectors in porcine corneas. The effects of epithelial debridement, relaxing incisions, and crosslink-mediated stiffening on surface wave velocity are also studied. METHODS A handheld prototype system was used to measure ultrasound surface wave propagation time between two fixed-distance transducers along a ten-position map. Repeatability was assessed with replicate measurements in 6 porcine corneas. In 12 porcine globes with controlled intraocular pressure (IOP), serial measurements were performed before and after epithelial removal, then after 250- and 750-μm-deep relaxing incisions. In human globes with constant intravitreal pressure, central wave velocity and transcorneal IOP measurements were compared before and after collagen cross-linking. RESULTS Measurement repeatability across all regions was between 2.2% and 8.1%. Epithelial removal resulted in increases in measured stiffness in 67% of eyes, but statistical power was insufficient to detect a systematic change. Wave velocity across a central incision decreased significantly after 250-μm keratotomy (P<.001), but did not undergo a significant further decrease with deeper keratotomy. Meridional stiffness changes consistent with coupling effects were detected after keratotomy. Surface wave velocity and transcorneal IOP measurements increased markedly after collagen cross-linking despite maintenance of a constant IOP. CONCLUSIONS Handheld corneal elastometry provides a repeatable measure of regional stiffness changes after relaxing incisions and collagen cross-linking in in vitro experiments. Surface wave elastometry allows focal assessment of corneal biomechanical properties that are relevant in refractive surgery, ectatic disease, and glaucoma. PMID:17269246

Ophthalmic Phenotypes and the Representativeness of Twin Data for the General Population

PubMed Central

Sanfilippo, Paul G.; Medland, Sarah E.; Hewitt, Alex W.; Kearns, Lisa S.; Ruddle, Jonathan B.; Sun, Cong; Hammond, Christopher J.; Young, Terri L.; Martin, Nicholas G.

2011-01-01

Purpose. To compare the distributional parameters for a series of ocular biometric traits between twins and their singleton siblings, to evaluate the generalizability of twin data, as used in heritability analyses to the general population. Methods. A series of birth, anthropometric, and 13 ocular biometric traits were selected for analysis: interpupillary distance (IPD), visual acuity (logMAR), spherical equivalent refractive error, corneal curvature, axial length, anterior chamber depth (ACD), central corneal thickness (CCT), intraocular pressure (IOP), optic disc, cup and rim areas, and measures of retinal vessel caliber; central retinal arteriolar equivalent (CRAE), and central retinal venular equivalent (CRVE). Structural equation modeling was used to test the assumption that the means and variances for each trait did not differ between twins and their siblings. Results. Significant differences in log-likelihood for birth weight and gestational age were observed between twins and siblings, with the latter being both heavier and closer to full-term at birth. Siblings were also found to have larger IPD and axial length, and better visual acuity compared with their twin counterparts. Refractive error, corneal curvature, ACD, CCT, optic disc parameters, and retinal vascular calibers did not differ significantly between the two groups. Conclusions. Twins are representative of the general population for some but not all measures of ocular biometry. Consequently, care should be taken when extrapolating twin data for these traits in heritability and other genetic studies. Birth weight differences between twins and siblings do not appear to account for the differences in ocular biometry observed in this study. PMID:21498610

Characterization of Ocular Biomechanics in Pellucid Marginal Degeneration.

PubMed

Lenk, Janine; Haustein, Michael; Terai, Naim; Spoerl, Eberhard; Raiskup, Frederik

2016-04-01

This study sought to investigate the diagnostic capacity of corneal biomechanical response parameters in a group of patients with pellucid marginal degeneration (PMD) using the Ocular Response Analyzer (ORA) and Corvis ST devices. In this prospective clinical study, we used the Corvis ST and ORA devices to investigate the ocular biomechanics of patients with PMD. Eighty-one eyes were included, and 2 study groups were formed: the PMD group (the study group, n = 29) and the control group (n = 52). We focused on 13 biomechanical parameters. Statistical analysis was performed using SPSS. Biomechanical parameters for the 2 groups were compared using analysis of covariance. The ORA results demonstrated that the Keratoconus Match Index was significantly lower in the PMD group than in the control group (0.031 ± 0.37 vs. 0.79 ± 0.33; P = 0.001). The 2 groups did not significantly differ with respect to intraocular pressure- and central corneal thickness-adjusted values for corneal hysteresis or corneal resistance factor. Regarding the Corvis parameters, differences between the control and PMD groups were detected for CorWmax amp (control 1.01 ± 0.01, PMD 1.06 ± 0.01; P = 0.020) and CorA2 t (control 21.78 ± 0.03, PMD 21.66 ± 0.04; P = 0.0003). We identified 2 Corvis parameters that could be used to characterize PMD and differentiate PMD corneas from normal corneas. These parameters support the hypothesis that there is significantly less deformation of the central cornea in PMD corneas than in healthy corneas. However, because useful "first-line" diagnostic devices for diagnosing PMD (such as Pentacam and the ORA) exist, the Corvis ST serves as an additional diagnostic tool that can also be used for long-term monitoring after diagnosis confirmation.

Evaluation of the Tear Function Tests and the Ocular Surface in First-Time Users of Silicone Hydrogel Contact Lenses.

PubMed

Yildiz Tasci, Yelda; Gürdal, Canan; Sarac, Ozge; Onusever, Aykut

2017-07-01

To evaluate the effects of three different silicone hydrogel contact lenses (SHCL), (balafilcon A, senofilcon A, and comfilcon A) on tear function tests, corneal thickness, and ocular surface cytology in first time contact lens users. In this prospective study, 120 eyes of 60 subjects were evaluated. Balafilcon A users were designated as group 1, senofilcon A users as group 2, and comfilcon A users as group 3. In all cases, before and after 6 months of contact lens wear, ocular surface disease index score (OSDI), tear breakup time (TBUT), Schirmer 1 test, central corneal thickness (CCT), central corneal epithelium thickness (CCET), and conjunctival impression cytology samples were evaluated. In group 1, 40 eyes of the 20 patients, in group 2, 40 eyes of the 20 patients, and in group 3, 40 eyes of the 20 patients were evaluated. The mean OSDI scores did not differ between the three groups after contact lens wear (p > 0.05). In group 1 and group 2, significant decrease was found in the mean TBUT 6 months after contact lens wear (p = 0.04, p < 0.001, respectively). In group 3, after 6 months of contact lens wear, the mean Schirmer 1 tear test was decreased significantly (p = 0.021). In all 3 groups, no significant change was observed in the mean CCT and CCET after contact lens wear (p > 0.05). After 6 months, the morphological changes in temporal and superior conjunctival epithelial cells were found to be significant in all groups (p < 0.001). Six months after SHCL wear, marked morphological changes occurred in the conjunctival epithelium. Tear function tests were also affected, while corneal thickness did not show any significant difference.

Embryonic development of the cornea in the eye of the clearnose skate, Raja eglanteria: I. Stromal development in the absence of an endothelium

NASA Technical Reports Server (NTRS)

Conrad, G. W.; Paulsen, A. Q.; Luer, C. A.; Spooner, B. S. (Principal Investigator)

1994-01-01

Embryos of the clearnose skate, Raja eglanteria, develop in sea water at 20-22 degrees C, hatching after 82 +/- 4 days (Luer and Gilbert, Environ. Biol. Fishes, 13:161-171, 1985). Eyes develop as steadily enlarging spheres whose corneas have the same radius of curvature as the sclera. The cornea begins development as a 2-cell thick epithelium beneath which by Day 12 there is only a basal lamina and a wispy matrix separating it from the underlying lens. This matrix, modified by Day 16, is displaced on Day 22 by a few orthogonal plies of fibrillar primary stroma. Ply number increases to at least 13 by Day 30, reaching the final number of 20 +/- 2 by Day 42. Stromal fibroblasts (keratocytes) appear at the corneal periphery by Day 22, and in increased numbers by Day 30, a time at which no keratocytes are seen in the central stroma. However, by Day 40, many fibroblasts are present at the corneal periphery, invading the primary stroma between plies, occasionally reaching even the central cornea. By Day 53, keratocytes are present between all plies, from corneal periphery to center. Thickness of each ply in this secondary stroma increases, but the number of plies remains the same as in the primary stroma. Bowman's layer, non-invaded matrix beneath the epithelial basal lamina, is not evident until Day 53. Sutural fibers, first seen on Day 22, originate in the corneal epithelial basal lamina, traversing perpendicularly the plies of the primary stroma. Sutural fibers persist throughout development of the secondary stroma and into adulthood. In contrast to chicks, skate corneas remain transparent throughout development, and never form an endothelium.

Patient-Specific Computational Modeling of Keratoconus Progression and Differential Responses to Collagen Cross-linking

PubMed Central

Sinha Roy, Abhijit

2011-01-01

Purpose. To model keratoconus (KC) progression and investigate the differential responses of central and eccentric cones to standard and alternative collagen cross-linking (CXL) patterns. Methods. Three-dimensional finite element models (FEMs) were generated with clinical tomography and IOP measurements. Graded reductions in regional corneal hyperelastic properties and thickness were imposed separately in the less affected eye of a KC patient. Topographic results, including maximum curvature and first-surface, higher-order aberrations (HOAs), were compared to those of the more affected contralateral eye. In two eyes with central and eccentric cones, a standard broad-beam CXL protocol was simulated with 200- and 300-μm treatment depths and compared to spatially graded broad-beam and cone-centered CXL simulations. Results. In a model of KC progression, maximum curvature and HOA increased as regional corneal hyperelastic properties were decreased. A topographic cone could be generated without a reduction in corneal thickness. Simulation of standard 9-mm-diameter CXL produced decreases in corneal curvature comparable to clinical reports and affected cone location. A 100-μm increase in CXL depth enhanced flattening by 24% to 34% and decreased HOA by 22% to 31%. Topographic effects were greatest with cone-centered CXL simulations. Conclusions. Progressive hyperelastic weakening of a cornea with subclinical KC produced topographic features of manifest KC. The clinical phenomenon of topographic flattening after CXL was replicated. The magnitude and higher-order optics of this response depended on IOP and the spatial distribution of stiffening relative to the cone location. Smaller diameter simulated treatments centered on the cone provided greater reductions in curvature and HOA than a standard broad-beam CXL pattern. PMID:22039252

[The correlations between corneal sensation, tear meniscus volume, and tear film osmolarity after femtosecond laser-assisted LASIK].

PubMed

Zhang, Luyan; Sun, Xiyu; Yu, Ye; Xiong, Yan; Cui, Yuxin; Wang, Qinmei; Hu, Liang

2016-01-01

To investigate the correlations between corneal sensation, tear meniscus volume, and tear film osmolarity after femtosecond laser-assisted LASIK (FS-LASIK) surgery. In this prospective clinical study, 31 patients undergoing FS-LASIK for myopia were recruited. The upper and lower tear meniscus volumes (UTMV and LTMV) were measured by customized anterior segment optical coherence tomography, tear film osmolarity was measured by a TearLab Osmolarity test device, central corneal sensation was measured by a Cochet-Bonner esthesiometer preoperatively, at 1 week, 1 and 3 months postoperatively. Repeated measures analysis of variance was used to evaluate whether the tear film osmolarity, tear meniscus volume, and corneal sensation were changed after surgery. The correlations between these variables were analyzed by the Pearson correlation analysis. The tear film osmolarity was (310.03 ± 16.48) mOsms/L preoperatively, (323.51 ± 15.92) mOsms/L at 1 week, (319.93 ± 14.27) mOsms/L at 1 month, and (314.97±12.91) mOsms/L at 3 months. The UTMV was (0.42±0.15), (0.25± 0.09), (0.30±0.11), and (0.35±0.09) μL, respectively; the LTMV was (0.60±0.21),(0.37±0.08), (0.44± 0.14), and (0.52±0.17) μL, respectively. The tear film osmolarity was significantly higher at 1 week and 1 month postoperatively compared with the baseline (P=0.001, 0.004), and reduced to the preoperative level at 3 months (P=0.573). The UTMV, LTMV, and corneal sensation values presented significant decreases at all postoperative time points (all P<0.05). The Pearson correlation analysis showed the postoperative UTMV had a weak relationship with corneal sensation at 1 week after surgery (r=0.356,P=0.005). There were significant correlations between the preoperative LTMV and corneal sensation at 1 week, 1 and 3 months (respectively, r=0.422, 0.366, 0.352;P=0.001, 0.004, 0.006). No significant correlations were found between the tear film osmolarity, tear meniscus volume, and corneal sensation after surgery (all P>0.05). The tear film osmolarity, tear meniscus volume, and corneal sensation became aggravated due to the FS-LASIK surgery procedures. There were significant correlations between the preoperative tear meniscus volume and recovery of corneal sensation early after surgery. A higher tear meniscus volume before surgery may contribute to a faster corneal sensation recovery.

Evaluation of prior photorefractive keratectomy in donor tissue.

PubMed

Terry, M A; Ousley, P J; Rich, L F; Wilson, D J

1999-05-01

To describe a case in which an eye donor had prior bilateral photorefractive keratectomies and to elucidate possible methods of evaluation and screening of donor tissue. Case report. A 62-year-old eye donor was reported to have received radial keratotomy before his death. Further investigation by the eye bank showed a history of photorefractive keratectomy (PRK), not radial keratotomy. The corneas were therefore not used for transplantation, and the eyes were evaluated by slit-lamp examination, photography, corneal topography, and histology. Slit-lamp and photographic examination did not indicate the presence of PRK ablations. Corneal topography mapping with the TMS-1 was relatively ambiguous for identifying PRK flattening, while multiple data formatting of the cornea with the Orbscan resulted in the strongest suggestion of prior PRK. Histologic analysis showed central corneal thinning and loss of Bowman's membrane consistent with PRK. In the absence of a positive donor history for PRK, current methods of screening donor tissue for prior PRK often are insufficient to exclude these corneas from use in transplantation. More refined placido imagery corneal topography or newer technologies such as the Orbscan may allow more sensitive and specific methods of donor tissue screening.

Pink hypopyon in a patient with Serratia marcescens corneal ulceration.

PubMed

Stefater, James A; Borkar, Durga S; Chodosh, James

2015-01-01

A 65-year-old woman presented to the emergency ward at the Massachusetts Eye and Ear Infirmary with 2 days of redness, irritation, photophobia, and diminished vision in her left eye. She was found to have a large central corneal ulcer with a small hypopyon. On the following day, after initiation of broad-spectrum antibiotics, the patient had improved symptoms but now had a 2-mm hypopyon that was distinctly pink in color. Cultures were positive for Serratia marcescens. A pink hypopyon, a rare occurrence, alerted the authors to a causative agent of Enterobacteriacae, either Klebsiella or Serratia. Immediate and intensive treatment was subsequently initiated.

Preliminary study of the association between corneal histocytological changes and surgically induced astigmatism after phacoemulsification.

PubMed

Du, Xing; Zhao, Guiqiu; Wang, Qing; Yang, Xian; Gao, Ang; Lin, Jing; Wang, Qian; Xu, Qiang

2014-11-20

Surgically induced astigmatism (SIA) was one of the factors that influences the desirable refractive outcome, and it was related to the length, type, location, structure of the incision and to the suture closure technique, etc. The aim was to evaluate the association of corneal histocytological changes with SIA after phacoemulsification. The study enrolled 68 cases of cataract patient (68 eyes). Corneal histocytological parameters at corneal incision, central cornea and contralateral incision obtained by confocal microscope through focusing (CMTF) were compared preoperatively and 1 week, 2 weeks, 1 month, 3 months and 6 months postoperatively. These biometric parameters included the endothelial cell density, keratocyte density of posterior stromal layer, and the morphological changes. SIA was calculated by Jaffe's vector analysis. 1 From preoperatively to 1 week, 2 weeks, 1 month, 3 months and 6 months postoperatively, the endothelail cell density was decreased significantly (p < 0.05). Keratocyte density of posterior stroma layer was increased significantly only at 1 week, 2 weeks, 1 month, 3 months postoperatively (p <0.05), but not statistically significant (p = 0.173) at 6 months postoperatively compared to preoperative values. 2 The histocytological observations indicated that the morphology changed significantly postoperatively at the corneal incision, including the cell absent area, wave-like area, dot-like and mass-like hyperreflection, stripe-like absent area, in the endothelial layer, and the keratocyte activation, microfolds, irregular hyporeflective or hyperreflective belt, and a little dot-like hyperreflection in the posterior stroma layer. 3 The reduction of the endothelial cell density at the corneal incision at 1 week, 2 weeks, 1 month postoperatively, were positively correlated with SIA (P1 week = 0.003, P2 weeks = 0.003, P1 month = 0.032), while others were not associated with SIA statistically. The reduction of endothelail cell density and the histocytological changes at the corneal incision were associated with SIA. The underlining mechanism needs further study.

Evaluation of Biomechanical Changes in Myopia Patients with Unsatisfactory Corneas After Femto Second-Laser In Situ Keratomileusis (FS-LASIK) Concurrent with Accelerated Corneal Collagen Cross-Linking Using Corvis-ST: Two-Year Follow-Up Results.

PubMed

Xu, Weiwei; Tao, Ye; Wang, Liqiang; Huang, Yifei

2017-07-27

BACKGROUND Some myopia patients with unsatisfactory corneas consider corneal refractive surgery for different reasons. Accelerated corneal collagen crosslinking (ACXL) is an effective method to enhance the resistance of the cornea. The present investigation was designed to evaluate the changes of biomechanical properties in patients with myopia and thin corneas after femtosecond-laser in situ keratomileusis (FS-LASIK) concurrent with ACXL. MATERIAL AND METHODS A prospective study was designed. A total of 22 eyes of 11 myopia astigmatism patients with unsatisfactory corneas were enrolled. The patients were assigned to femtosecond-laser in situ keratomileusis concurrent with accelerated corneal collagen crosslinking (FS-LASIK-ACXL). The follow-up duration was 24 months. Manifest refraction, uncorrected (UDVA), and corrected distance visual acuity (CDVA), ultra-high-speed camera (Corvis-ST), corneal topography, anterior segment OCT (AS-OCT), Pentacam, and endothelial cell density (ECD) were examined before and after the operation. The corneal biomechanical and refractive data was analyzed using SAS9.3. Data were analyzed through normal distribution test and variance of analysis. The difference was considered as statistically significant when p<0.05. RESULTS The steep K (Ks) values, flat K (Kf) values, average keratometry values (Avek) values, and central corneal thickness (CCT) declined significantly after FS-LASIK-ACXL operation. The values of first applanation length (A1L), the second applanation length (A2L), the first applanation velocity (A1V), the second applanation velocity (A2V), deformation amplitude (DA), highest concavity peak distance (PD), and radius of curvature at the time of highest concavity (HCR) did not show significant difference after the operation. CONCLUSIONS FS-LASIK-ACXL is an effective and safe surgery for improving visual acuity for myopic patients with thin corneas, and it does not increase the risk of iatrogenic keratectasia.

Neurturin-deficient mice develop dry eye and keratoconjunctivitis sicca.

PubMed

Song, Xiu Jun; Li, De-Quan; Farley, William; Luo, Li Hui; Heuckeroth, Robert O; Milbrandt, Jeffrey; Pflugfelder, Stephen C

2003-10-01

Neurturin has been identified as a neurotrophic factor for parasympathetic neurons. Neurturin-deficient (NRTN(-/-)) mice have defective parasympathetic innervation of their lacrimal glands. This study was conducted to evaluate tear function and ocular surface phenotype in NRTN(-/-) mice. Determined by tail genomic DNA PCR, 25 NRTN(-/-) mice and 17 neurturin-normal (NRTN(+/+)) mice aged 6 weeks to 4 months were evaluated. Aqueous tear production, tear fluorescein clearance and corneal sensation were serially measured. Corneal permeability to AlexaFluor dextran (AFD; Molecular Probes, Eugene, OR) was measured by a fluorometric assay at 485 nm excitation and 530 nm emission. Histology was evaluated in PAS-stained sections. Mucin and HLA class II (IA) antigen were assessed by immunofluorescent staining. Tear IL-1beta was measured by ELISA, and tear matrix metalloproteinase (MMP)-9 by zymography. Gene expression in the corneal epithelia was analyzed by semiquantitative RT-PCR. In comparison to that in age-matched NRTN(+/+) mice, aqueous tear production, tear fluorescein clearance, and corneal sensation were significantly reduced in NRTN(-/-) mice, whereas corneal permeability to AFD was significantly increased. Immunoreactive MUC-4 and -5AC mucin and goblet cell density (P < 0.001) in the conjunctiva of NRTN(-/-) mice were lower than in NRTN(+/+) mice. The expression of MUC-1 and -4 mRNA by the corneal epithelium was reduced in NRTN(-/-) mice. There were a significantly greater number of IA antigen-positive conjunctival epithelial cells in NRTN(-/-) mice than NRTN(+/+) mice. Tear fluid IL-1beta and MMP-9 concentrations and the expression of IL-1beta, TNF-alpha, macrophage inflammatory protein (MIP)-2, cytokine-induced neutrophil chemoattractant (KC), and MMP-9 mRNA by the corneal epithelia were significantly increased in NRTN(-/-) mice, compared with NRTN(+/+) mice. Neurturin-deficient mice show phenotypic changes and ocular surface inflammation that mimic human keratoconjunctivitis sicca. This model supports the importance of a functional ocular surface-central nervous system-lacrimal gland sensory-autonomic neural network in maintaining ocular surface health and homeostasis.

Reversible Femtosecond Laser-Assisted Myopia Correction: A Non-Human Primate Study of Lenticule Re-Implantation after Refractive Lenticule Extraction

PubMed Central

Chaurasia, Shyam S.; Lee, Wing S.; Tan, Donald T.; Mehta, Jodhbir S.

2013-01-01

LASIK (laser-assisted in situ keratomileusis) is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap. Correction of refractive error is achieved by the resulting change in the curvature of the cornea and is limited by central corneal thickness, as a thin residual stromal bed may result in biomechanical instability of the cornea. A recently developed alternative to LASIK called Refractive Lenticule Extraction (ReLEx) utilizes solely a femtosecond laser (FSL) to incise an intrastromal refractive lenticule (RL), which results in reshaping the corneal curvature and correcting the myopia and/or astigmatism. As the RL is extracted intact in the ReLEx, we hypothesized that it could be cryopreserved and re-implanted at a later date to restore corneal stromal volume, in the event of keratectasia, making ReLEx a potentially reversible procedure, unlike LASIK. In this study, we re-implanted cryopreserved RLs in a non-human primate model of ReLEx. Mild intrastromal haze, noted during the first 2 weeks after re-implantation, subsided after 8 weeks. Refractive parameters including corneal thickness, anterior curvature and refractive error indices were restored to near pre-operative values after the re-implantation. Immunohistochemistry revealed no myofibroblast formation or abnormal collagen type I expression after 8 weeks, and a significant attenuation of fibronectin and tenascin expression from week 8 to 16 after re-implantation. In addition, keratocyte re-population could be found along the implanted RL interfaces. Our findings suggest that RL cryopreservation and re-implantation after ReLEx appears feasible, suggesting the possibility of potential reversibility of the procedure, and possible future uses of RLs in treating other corneal disorders and refractive errors. PMID:23826194

The effect of standard and high-fluence corneal cross-linking (CXL) on cornea and limbus.

PubMed

Richoz, Olivier; Tabibian, David; Hammer, Arthur; Majo, François; Nicolas, Michael; Hafezi, Farhad

2014-07-22

When treating peripheral ectatic disease-like pellucid marginal degeneration (PMD), corneal cross-linking with UV-A and riboflavin (CXL) must be applied eccentrically to the periphery of the lower cornea, partly irradiating the corneal limbus. Here, we investigated the effect of standard and double-standard fluence corneal cross-linking with riboflavin and UV-A (CXL) on cornea and corneal limbus in the rabbit eye in vivo. Epithelium-off CXL was performed in male New Zealand White rabbits with two irradiation diameters (7 mm central cornea, 13 mm cornea and limbus), using standard fluence (5.4 J/cm(2)) and double-standard fluence (10.8 J/cm(2)) settings. Controls were subjected to epithelial removal and riboflavin instillation, but were not irradiated with UV-A. Following CXL, animals were examined daily until complete closure of the epithelium, and at 7, 14, 21, and 28 days. Animals were killed and a corneoscleral button was excised and processed for light microscopy and immunohistochemistry. For both irradiation diameters and fluences tested, no signs of endothelial damage or limbal vessel thrombosis were observed, and time to re-epithelialization was similar to untreated controls. Histological and immunohistochemical analysis revealed no differences in the p63 putative stem cell marker expression pattern. Even when using fluence twice as high as the one used in current clinical CXL settings, circumferential UV-A irradiation of the corneal limbus does not alter the regenerative capacity of the limbal epithelial cells, and the expression pattern of the putative stem cell marker p63 remains unchanged. This suggests that eccentric CXL may be performed safely in PMD. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Keratoconus and Normal-Tension Glaucoma: A Study of the Possible Association with Abnormal Biomechanical Properties as Measured by Corneal Hysteresis (An AOS Thesis)

PubMed Central

Cohen, Elisabeth J.

2009-01-01

Purpose: To test the hypothesis that keratoconus and pellucid patients who have glaucoma or are suspected of having glaucoma have lower corneal hysteresis (CH) and/or corneal resistance factor (CRF) measurements compared to controls. Methods: A prospective study at a tertiary eye center of keratoconus and pellucid patients with glaucoma or suspected of having glaucoma, and age-matched keratoconus and pellucid controls, was performed. After informed consent was obtained, corneal topography, ocular response analyzer measurements, pachymetry, intraocular pressure, A-scan measurements, Humphrey visual fields (VFs), and disc photos were done. Analyses compared cases to controls on primary (CH and CRF) and secondary variables. Disc photos and VFs were rated in a masked fashion. Results: The mean CH (8.2, SD=1.6, vs 8.3, SD=1.5) and CRF (7.3, SD=2.0, vs 6.9, SD=2.1) were low and did not differ significantly between 20 study patients (29 eyes) and 40 control patients (61 eyes), respectively. CH had a negative, significant correlation with maximum corneal curvature by topography (P < .002) and positive, significant correlation with central corneal thickness (P < .003). The mean cup-disc ratio was larger among cases than controls (0.54, SD=0.20, vs 0.38, SD=0.20; P = .003). VFs were suggestive of glaucoma more often among the study eyes than controls (11 of 29, 37.9%, vs 8 of 60, 13.3%; P =.019). Conclusions: CH was low in study and control patients and was correlated with severity of keratoconus/pellucid, but not with glaucoma/suspected glaucoma or control status. Evidence of glaucoma was more common in study eyes than controls, but was present in both. PMID:20126503

Corneal wound healing after photorefractive keratectomy: a 3-year confocal microscopy study.

PubMed Central

Erie, Jay C

2003-01-01

PURPOSE: To perform a sequential quantitative analysis of corneal wound healing after photorefractive keratectomy (PRK) by using confocal microscopy in vivo. METHODS: In a prospective, nonrandomized, comparative trial performed in an institutional setting, 24 eyes of 14 patients received PRK to correct refractive errors between -1.25 and -5.75 D. Central corneas were examined preoperatively and at 1 day, 5 days, and 1, 3, 6, 12, 24, and 36 months after PRK by using confocal microscopy. A masked observer randomly examined 3 to 6 confocal scans per eye per visit to determine epithelial and stromal thickness, keratocyte density in 5 anterior-posterior stromal layers, corneal nerve density in the subbasal region and the stroma, and corneal light backscattering (corneal haze). RESULTS: Epithelial thickness increased 21% (P < .001) by 12 months after PRK and thereafter remained unchanged to 36 months after PRK. There was no change in stromal thickness between 1 and 36 months after PRK (P = .35). The dense keratocyte population in the preoperative anterior 10% of the stroma (32,380 +/- 5,848 cells/mm3) that was partially or completely removed during photoablation was not reconstituted at 36 months in the anterior 10% of the post-PRK stroma (17,720 +/- 4,308 cells/mm3, P < .001). Subbasal nerve fiber bundle density was decreased 60% at 12 months after PRK (P < .001) before returning to densities at 24 and 36 months after PRK that were not significantly different from preoperative values (P = 1.0). Activated keratocytes and corneal haze peaked at 3 months after PRK. CONCLUSIONS: Wounding of the cornea by PRK alters the normal structure, cellularity, and innervation of the cornea for up to 36 months. PMID:14971584

Measurement of an Elasticity Map in the Human Cornea

PubMed Central

Mikula, Eric R.; Jester, James V.; Juhasz, Tibor

2016-01-01

Purpose The biomechanical properties of the cornea have an important role in determining the shape of the cornea and visual acuity. Since the cornea is a nonhomogeneous tissue, it is thought that the elastic properties vary throughout the cornea. We aim to measure a map of corneal elasticity across the cornea. Methods An acoustic radiation force elasticity microscope (ARFEM) was used to create a map of corneal elasticity in the human cornea. This ARFEM uses a low frequency, high intensity acoustic force to displace a femtosecond laser-generated microbubble, while using a high frequency, low intensity ultrasound to monitor the position of the microbubble within the cornea. From the displacement of the bubble and the magnitude of the acoustic radiation force, the local value of corneal elasticity is calculated in the direction of the displacement. Measurements were conducted at 6 locations, ranging from the central to peripheral cornea at anterior and posterior depths. Results The mean anterior elastic moduli were 4.2 ± 1.2, 3.4 ± 0.7, and 1.9 ± 0.7 kPa in the central, mid, and peripheral regions, respectively, while the posterior elastic moduli were 2.3 ± 0.7, 1.6 ± 0.3, and 2.9 ± 1.2 kPa in the same radial locations. Conclusions We found that there is a unique distribution of elasticity axially and radially throughout the cornea. PMID:27327584

Twelve-Year Follow-Up of Laser In Situ Keratomileusis for Moderate to High Myopia

PubMed Central

Ikeda, Tetsuya; Igarashi, Akihito; Kasahara, Sumie

2017-01-01

Purpose To assess the long-term clinical outcomes of conventional laser in situ keratomileusis (LASIK) for moderate to high myopia. Methods We retrospectively examined sixty-eight eyes of 37 consecutive patients who underwent conventional LASIK for the correction of myopia (−3.00 to −12.75 diopters (D)). At 3 months and 1, 4, 8, and 12 years postoperatively, we assessed the safety, efficacy, predictability, stability, mean keratometry, central corneal thickness, and adverse events. Results The safety and efficacy indices were 0.82 ± 0.29 and 0.67 ± 0.37, respectively, 12 years postoperatively. At 12 years, 53% and 75% of the eyes were within 0.5 and 1.0 D, respectively, of the targeted correction. Manifest refraction changes of −0.74 ± 0.99 D occurred from 3 months to 12 years after LASIK (p < 0.001). We found a significant correlation of refractive regression with the changes in keratometric readings from 3 months to 12 years postoperatively (Pearson correlation coefficient, r = −0.28, p = 0.02), but not with the changes in central corneal thickness (r = −0.08, p = 0.63). No vision-threatening complications occurred in any case. Conclusions Conventional LASIK offered good safety outcomes during the 12-year observation period. However, the efficacy and the predictability gradually decreased with time owing to myopic regression in relation to corneal steepening. PMID:28596969

Twelve-Year Follow-Up of Laser In Situ Keratomileusis for Moderate to High Myopia.

PubMed

Ikeda, Tetsuya; Shimizu, Kimiya; Igarashi, Akihito; Kasahara, Sumie; Kamiya, Kazutaka

2017-01-01

To assess the long-term clinical outcomes of conventional laser in situ keratomileusis (LASIK) for moderate to high myopia. We retrospectively examined sixty-eight eyes of 37 consecutive patients who underwent conventional LASIK for the correction of myopia (-3.00 to -12.75 diopters (D)). At 3 months and 1, 4, 8, and 12 years postoperatively, we assessed the safety, efficacy, predictability, stability, mean keratometry, central corneal thickness, and adverse events. The safety and efficacy indices were 0.82 ± 0.29 and 0.67 ± 0.37, respectively, 12 years postoperatively. At 12 years, 53% and 75% of the eyes were within 0.5 and 1.0 D, respectively, of the targeted correction. Manifest refraction changes of -0.74 ± 0.99 D occurred from 3 months to 12 years after LASIK ( p < 0.001). We found a significant correlation of refractive regression with the changes in keratometric readings from 3 months to 12 years postoperatively (Pearson correlation coefficient, r = -0.28, p = 0.02), but not with the changes in central corneal thickness ( r = -0.08, p = 0.63). No vision-threatening complications occurred in any case. Conventional LASIK offered good safety outcomes during the 12-year observation period. However, the efficacy and the predictability gradually decreased with time owing to myopic regression in relation to corneal steepening.

In vivo laser confocal microscopy findings of a cornea with osteogenesis imperfecta.

PubMed

Kobayashi, Akira; Higashide, Tomomi; Yokogawa, Hideaki; Yamazaki, Natsuko; Masaki, Toshinori; Sugiyama, Kazuhisa

2014-01-01

To report the in vivo laser confocal microscopy findings of a cornea with osteogenesis imperfecta (OI) with special attention to the abnormality of Bowman's layer and sub-Bowman's fibrous structures (K-structures). Two patients (67-year-old male and his 26-year-old son) with OI type I were included in this study. Slit lamp biomicroscopic and in vivo laser confocal microscopic examinations were performed for both patients. Central corneal thickness and central endothelial cell density were also measured. Although the corneas looked clear with normal endothelial density for both eyes in both patients, they were quite thin (386 μm oculus dexter (OD) (the right eye) and 384 μm oculus sinister (OS) (the left eye) in the father and 430 μm OD and 425 μm OS in the son). In both patients, slit lamp biomicroscopic and in vivo laser confocal microscopic examination showed similar results. Anterior corneal mosaics produced by rubbing the eyelid under fluorescein were completely absent in both eyes. In vivo laser confocal microscopy revealed an absent or atrophic Bowman's layer; a trace of a presumed Bowman's layer and/or basement membrane was barely visible with high intensity. Additionally, K-structures were completely absent in both eyes. The absence of K-structures and fluorescein anterior corneal mosaics strongly suggested an abnormality of Bowman's layer in these OI patients.

Reproducibility of the measurement of central corneal thickness in healthy subjects obtained with the optical low coherence reflectometry pachymeter and comparison with the ultrasonic pachymetry.

PubMed

Garza-Leon, Manuel; Plancarte-Lozano, Eduardo; Valle-Penella, Agustín Del; Guzmán-Martínez, María de Lourdes; Villarreal-González, Andrés

2018-01-01

Corneal pachymetry is widely used for refractive surgery and follow up in keratoconus, accurate measurement is essential for a safe surgery. To assess intraobserver reliability of central corneal thickness (CCT) measurements using optical low-coherence reflectometry (OLCR) technology and its agreement with ultrasonic pachymeter (US). Randomized and prospective comparative evaluation of diagnostic technology. One randomly healthy eye of subjects was scanned three times with both devices. Intraobserver within-subject standard deviation (Sw), coefficient of variation (CVw) and intraclass correlation coefficient (ICC) were obtained for reliability analysis; for study agreement, data were analyzed using the paired-sample t test and the Bland-Altman LoA method. The mean of three scans of each equipment was used to assess the LoA. The study enrolled 30 eyes of 30 subjects with average age of 28.70 ± 8.06 years. For repeatability, the Sw were 3.41 and 5.96 µ, the intraobserver CVw was 2 and 4% and ICC 0.991 and 0.988, for OLCR and US respectively. The mean CCT difference between OLCR and US was 8.90 ± 9.03 µ (95% confidence interval: 5.52-2.27 µ), and the LoA was 35.40 µ. OLCR technology provided reliable intraobserver CCT measurements. Both pachymetry measurements may be used interchangeably with minimum calibration adjustment. Copyright: © 2018 Permanyer.

Specialized moisture retention eyewear for evaporative dry eye.

PubMed

Waduthantri, Samanthila; Tan, Chien Hua; Fong, Yee Wei; Tong, Louis

2015-05-01

To evaluate the suitablity of commercially available moisture retention eyewear for treating evaporative dry eye. Eleven patients with evaporative dry eyes were prescibed moisture retention eyewear for 3 months in addition to regular lubricant eye drops. Frequency and severity of dry eye symptoms, corneal fluorescein staining and tear break up time (TBUT) were evaluated at baseline and 3-month post-treatment. Main outcome measure was global symptom score (based on severity and frequency of dry eye symptoms on a visual analog scale) and secondary outcomes were changes in sectoral corneal fluorescein staining and tear break up time (TBUT) from pre-treatment level. There was a significant improvement in dry eye symptoms after using moisture retention eyewear for 3 months (p < 0.05). Corneal fluorescein staining in all five zones of the cornea in both eyes improved significantly (p < 0.05). There was no significant improvement in TBUT. Patients used ocular lubricants less frequently (p < 0.05) compared to the commencement of the study. Patients found moisture retention eyewear to be useful in relieving dry eye symptoms in windy, air-conditioned environments or when doing vision-related daily tasks. This study shows that moisture retention eyewear might be a valuable adjunct in management of evaporative dry eye and this new design of commercially available eyewear could have a good acceptability rate.

Corneal biomechanical properties in healthy children measured by corneal visualization scheimpflug technology.

PubMed

He, Miao; Ding, Hui; He, Hong; Zhang, Chi; Liu, Liangping; Zhong, Xingwu

2017-05-17

The aim of this study was to evaluate corneal biomechanical properties in a population of healthy children in China using corneal visualization Scheimpflug technology (CST). All children underwent complete bi-ocular examinations. CST provided intraocular pressure (IOP) and corneal biomechanical parameters, including time, velocity, length and deformation amplitude at first applanation (A1T, A1V, A1L, A1DA), at second applanation (A2T, A2V, A2L, A2DA), highest concavity time (HCT), maximum deformation amplitude (MDA), peak distance (PD), and radius of curvature (RoC). Pearson correlation analysis was used to assess the impacts of demographic factors, central corneal thickness (CCT), spherical equivalent (SE), and IOP on corneal biomechanics. One hundred eight subjects (32 girls and 76 boys) with the mean age of 10.80 ± 4.13 years (range 4 to18 years) were included in the final analyses. The right and left eyes were highly symmetrical in SE (p = 0.082), IOP (p = 0.235), or CCT (p = 0.210). Mean A1T of the right eyes was 7.424 ± 0.340 ms; the left eyes 7.451 ± 0.365 ms. MDA was 0.993 ± 0.102 mm in the right eyes and 0.982 ± 0.100 mm in the left eyes. Mean HCT of the right eyes was 16.675 ± 0.502 ms; the left eyes 16.735 ± 0.555 ms. All CST parameters of both eye were remarkably symmetrical with the exception of A2L (p = 0.006), A1DA (p = 0.025). The majority of CST parameters of both eyes were significantly correlated with CCT and IOP (p < 0.05). However, age, SE, and sex exert little influence on the CST measurements. This study found interocular symmetry in corneal biomechanics in healthy children eyes. Several CST biomechanical parameters in children are modified by CCT and IOP.

Dimensional stability of lathe cut C.A.B. lenses.

PubMed

Pearson, R M

1978-08-01

Measurements of the back central optical radius in the course of 336 hours of hydration of lathe cut corneal lenses disclosed changes in curvature which were more rapid and of greater magnitude than those previously reported for poly (methyl methacrylate) lenses.

Excimer laser calibration system.

PubMed

Gottsch, J D; Rencs, E V; Cambier, J L; Hall, D; Azar, D T; Stark, W J

1996-01-01

Excimer laser photoablation for refractive and therapeutic keratectomies has been demonstrated to be feasible and practicable. However, corneal laser ablations are not without problems, including the delivery and maintenance of a homogeneous beam. We have developed an excimer laser calibration system capable of characterizing a laser ablation profile. Beam homogeneity is determined by the analysis of a polymethylmethacrylate (PMMA)-based thin-film using video capture and image processing. The ablation profile is presented as a color-coded map. Interpolation of excimer calibration system analysis provides a three-dimensional representation of elevation profiles that correlates with two-dimensional scanning profilometry. Excimer calibration analysis was performed before treating a monkey undergoing phototherapeutic keratectomy and two human subjects undergoing myopic spherocylindrical photorefractive keratectomy. Excimer calibration analysis was performed before and after laser refurbishing. Laser ablation profiles in PMMA are resolved by the excimer calibration system to .006 microns/pulse. Correlations with ablative patterns in a monkey cornea were demonstrated with preoperative and postoperative keratometry using corneal topography, and two human subjects using video-keratography. Excimer calibration analysis predicted a central-steep-island ablative pattern with the VISX Twenty/Twenty laser, which was confirmed by corneal topography immediately postoperatively and at 1 week after reepithelialization in the monkey. Predicted central steep islands in the two human subjects were confirmed by video-keratography at 1 week and at 1 month. Subsequent technical refurbishing of the laser resulted in a beam with an overall increased ablation rate measured as microns/pulse with a donut ablation profile. A patient treated after repair of the laser electrodes demonstrated no central island. This excimer laser calibration system can precisely detect laser-beam ablation profiles. The calibration system correctly predicted central islands after excimer photoablation in a treated monkey cornea and in two treated human subjects. Detection of excimer-laser-beam ablation profiles may be useful for precise calibration of excimer lasers before human photorefractive and therapeutic surgery.

A comparison of glycosaminoglycan distributions, keratan sulphate sulphation patterns and collagen fibril architecture from central to peripheral regions of the bovine cornea

PubMed Central

Ho, Leona T.Y.; Harris, Anthony M.; Tanioka, Hidetoshi; Yagi, Naoto; Kinoshita, Shigeru; Caterson, Bruce; Quantock, Andrew J.; Young, Robert D.; Meek, Keith M.

2014-01-01

This study investigated changes in collagen fibril architecture and the sulphation status of keratan sulphate (KS) glycosaminoglycan (GAG) epitopes from central to peripheral corneal regions. Freshly excised adult bovine corneal tissue was examined as a function of radial position from the centre of the cornea outwards. Corneal thickness, tissue hydration, hydroxyproline content, and the total amount of sulphated GAG were all measured. High and low-sulphated epitopes of keratan sulphate were studied by immunohistochemistry and quantified by ELISA. Chondroitin sulphate (CS) and dermatan sulphate (DS) distributions were observed by immunohistochemistry following specific enzyme digestions. Electron microscopy and X-ray fibre diffraction were used to ascertain collagen fibril architecture. The bovine cornea was 1021 ± 5.42 μm thick at its outer periphery, defined as 9–12 mm from the corneal centre, compared to 844 ± 8.10 μm at the centre. The outer periphery of the cornea was marginally, but not significantly, more hydrated than the centre (H = 4.3 vs. H = 3.7), and was more abundant in hydroxyproline (0.12 vs. 0.06 mg/mg dry weight of cornea). DMMB assays indicated no change in the total amount of sulphated GAG across the cornea. Immunohistochemistry revealed the presence of both high- and low-sulphated epitopes of KS, as well as DS, throughout the cornea, and CS only in the peripheral cornea before the limbus. Quantification by ELISA, disclosed that although both high- and low-sulphated KS remained constant throughout stromal depth at different radial positions, high-sulphated epitopes remained constant from the corneal centre to outer-periphery, whereas low-sulphated epitopes increased significantly. Both small angle X-ray diffraction and TEM analysis revealed that collagen fibril diameter remained relatively constant until the outer periphery was reached, after which fibrils became more widely spaced (from small angle x-ray diffraction analysis) and of larger diameter as they approached the sclera. Depth-profiled synchrotron microbeam analyses showed that, at different radial positions from the corneal centre outwards, fibril diameter was greater superficially than in deeper stromal regions. The interfibrillar spacing was also higher at mid-depth in the stroma than it was in anterior and posterior stromal regions. Collagen fibrils in the bovine cornea exhibited a fairly consistent spacing and diameter from the corneal centre to the 12 mm radial position, after which a significant increase was seen. While the constancy of the overall sulphation levels of proteoglycans in the cornea may correlate with the fibrillar architecture, there was no correlation between the latter and the distribution of low-sulphated KS. PMID:25019467

The use of WaveLight® Contoura to create a uniform cornea: the LYRA Protocol. Part 1: the effect of higher-order corneal aberrations on refractive astigmatism

PubMed Central

Motwani, Manoj

2017-01-01

Purpose To demonstrate how higher-order corneal aberrations can cancel out, modify, or induce lower-order corneal astigmatism. Patients and methods Six representative eyes are presented that show different scenarios in which higher-order aberrations interacting with corneal astigmatism can affect the manifest refraction. WaveLight® Contoura ablation maps showing the higher-order aberrations are shown, as are results of correction with full measured correction using the LYRA (Layer Yolked Reduction of Astigmatism) Protocol. Results Higher-order corneal aberrations such as trefoil, quadrafoil, and coma can create ovalization of the central cornea, which can interact with the ovalization caused by lower-order astigmatism to either induce, cancel out, or modify the manifest refraction. Contoura processing successfully determines the linkage of these interactions resulting in full astigmatism removal. Purely lenticular astigmatism appears to be rare, but a case is also demonstrated. The author theorizes that all aberrations require cerebral compensatory processing and can be removed, supported by the facts that full removal of aberrations and its linkage with lower-order astigmatism with the LYRA Protocol has not resulted in worse or unacceptable vision for any patients. Conclusion Higher-order aberrations interacting with lower-order astigmatism is the main reason for the differences between manifest refraction and Contoura measured astigmatism, and the linkage between these interactions can be successfully treated using Contoura and the LYRA Protocol. Lenticular astigmatism is relatively rare. PMID:28553069

The use of WaveLight® Contoura to create a uniform cornea: the LYRA Protocol. Part 1: the effect of higher-order corneal aberrations on refractive astigmatism.

PubMed

Motwani, Manoj

2017-01-01

To demonstrate how higher-order corneal aberrations can cancel out, modify, or induce lower-order corneal astigmatism. Six representative eyes are presented that show different scenarios in which higher-order aberrations interacting with corneal astigmatism can affect the manifest refraction. WaveLight ® Contoura ablation maps showing the higher-order aberrations are shown, as are results of correction with full measured correction using the LYRA (Layer Yolked Reduction of Astigmatism) Protocol. Higher-order corneal aberrations such as trefoil, quadrafoil, and coma can create ovalization of the central cornea, which can interact with the ovalization caused by lower-order astigmatism to either induce, cancel out, or modify the manifest refraction. Contoura processing successfully determines the linkage of these interactions resulting in full astigmatism removal. Purely lenticular astigmatism appears to be rare, but a case is also demonstrated. The author theorizes that all aberrations require cerebral compensatory processing and can be removed, supported by the facts that full removal of aberrations and its linkage with lower-order astigmatism with the LYRA Protocol has not resulted in worse or unacceptable vision for any patients. Higher-order aberrations interacting with lower-order astigmatism is the main reason for the differences between manifest refraction and Contoura measured astigmatism, and the linkage between these interactions can be successfully treated using Contoura and the LYRA Protocol. Lenticular astigmatism is relatively rare.

Identification of biomechanical properties of the cornea: the ocular response analyzer.

PubMed

Terai, Naim; Raiskup, Frederik; Haustein, Michael; Pillunat, Lutz E; Spoerl, Eberhard

2012-07-01

Several methods have been devised for measuring geometric parameters of the cornea but, until now, the biomechanics of the cornea have been largely ignored. The relatively new Ocular Response Analyzer (ORA) provides such biomechanical information. In order to correctly interpret the underlying biomechanics of ORA data, we review reported ORA measurements and provide a compendium of factors influencing these measurements, with discussion of possible explanations for ORA measurement results. This review comprised a literature search using "ocular response analyzer" and "ocular response analyser" as keywords. We reviewed and compared reported results from recent ORA studies so obtained, with an eye to understanding corneal biomechanics. Several ORA biomechanical parameters of the cornea - corneal hysteresis (CH) and corneal resistant factor (CRF) - characterize the viscoelastic properties of the cornea, especially those of the ground substance. The impact on CH and CRF values of various independent factors, e.g. intraocular pressure (IOP), age, central corneal thickness (CCT), and corneal swelling, are discussed. The impact on CH and CRF of treatment-related structural changes of the cornea, i.e. those occurring after refractive surgical procedures, placement of intracorneal rings, and collagen crosslinking (CXL), as well as pathological changes of the cornea, e.g. those resulting from keratoconus, edema, and glaucoma, are discussed. Changes in CRF and CH may be reflective of structural changes in the ground substance of the cornea. Thus, ORA provides invaluable information for delineating biomechanical conditions pertaining to the cornea, with special regard to ocular diseases, e.g. keratoconus and glaucoma.

Corneal and Retinal Neuronal Degeneration in Early Stages of Diabetic Retinopathy.

PubMed

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

2017-12-01

To examine the neuronal structural integrity of cornea and retina as markers for neuronal degeneration in nonproliferative diabetic retinopathy (NPDR). Participants were recruited from the broader Brisbane community, Queensland, Australia. Two hundred forty-one participants (187 with diabetes and 54 nondiabetic controls) were examined. Diabetic retinopathy (DR) was graded according to the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. Corneal nerve fiber length (CNFL), corneal nerve branch density (CNBD), corneal nerve fiber tortuosity (CNFT), full retinal thickness, retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), focal (FLV) and global loss volumes (GLV), hemoglobin A1c (HbA1c), nephropathy, neuropathy, and cardiovascular measures were examined. The central zone (P = 0.174), parafoveal thickness (P = 0.090), perifovea (P = 0.592), RNFL (P = 0.866), GCC (P = 0.798), and GCC GLV (P = 0.338) did not differ significantly between the groups. In comparison to the control group, those with very mild NPDR and those with mild NPDR had significantly higher focal loss in GCC volume (P = 0.036). CNFL was significantly lower in those with mild NPDR (P = 0.004) in comparison to the control group and those with no DR. The CNBD (P = 0.094) and CNFT (P = 0.458) did not differ between the groups. Both corneal and retinal neuronal degeneration may occur in early stages of diabetic retinopathy. Further studies are required to examine these potential markers for neuronal degeneration in the absence of clinical signs of DR.

The Progression of Haze Formation in Rabbit Corneas Following Phototherapeutic Keratectomy

PubMed Central

Gibson, Daniel J.; Tuli, Sonal S.; Schultz, Gregory S.

2013-01-01

Purpose. To determine the topographical location and time course of development of corneal haze in a phototherapeutic keratectomy model using slit lamp examination, macrophotography, quantitative image analysis, and immunofluorescence staining of corneal sections. Methods. Rabbit corneas were ablated with an excimer laser and were observed and graded for haze via slit lamp, imaged, and graded by macrophotography. Corneal sections were stained for α-smooth muscle actin (α-SMA) and tenascin-C (TNC). The distribution of haze imaged in the macrophotographs and density of α-SMA and TNC staining were compared. A daily image time course of haze formation was generated using macrophotography. Results. The first signs of corneal haze were apparent shortly after reepithelialization. The haze was distributed as a ring at the wound margin in all cases, while nearly all corneas also had some central islands of haze initiation. With time, the haze spread within the ablated zone and intensified. The pattern of immunofluorescent staining for α-SMA and TNC at the wound margin mirrored the haze distribution, spread, and intensification with time. Conclusions. The initiation and spread of subepithelial haze begins shortly after reepithelialization. The haze then spreads from the loci of initiation and becomes more dense with time, maturing as early as 14 days after wounding. The improved temporal and spatial resolution provided by these data improve the current model of light-scattering haze formation in wounded corneas, which will improve the design of studies aimed at maintaining corneal clarity following acute injury or surgery. PMID:23800768

NaK-ATPase pump sites in cultured bovine corneal endothelium of varying cell density at confluence.

PubMed

Crawford, K M; Ernst, S A; Meyer, R F; MacCallum, D K

1995-06-01

The driving force for ion and water flow necessary for efficient deturgesence of the corneal stroma resides in the ouabain-sensitive sodium (Na) pump of corneal endothelial cells. Using a cell culture model of corneal endothelial cell hypertrophy, the authors examined the expression of Na pumps at the cell surface to see how this central element of the endothelial pump changed as corneal endothelial cell density decreased to a level associated with corneal decompensation in vivo. 3H-ouabain binding to NaK-ATPase at saturating conditions was used to quantitate the number of Na pump sites on cultured bovine corneal endothelial cells as the confluent density decreased from approximately 2750 cells/mm2 to approximately 275 cells/mm2. The mean number of Na pump sites per cell at confluence (1.92 +/- 0.07 x 10(6)) did not change as the cell density decreased 2.7-fold from 2763 cells/mm2 to 1000 cells/mm2. However, pump site expression doubled to approximately 4 x 10(6) sites/cell as the cell density decreased from 1000 cells/mm2 to 275 cells/mm2. Despite the incremental increase in Na pump site expression that occurred as the cells hypertrophied below a density of 1000/mm2 to achieve confluence, this increase was insufficient to prevent a decrease in Na pump site density of the intact monolayer, expressed as pump sites/mm2. The confluent cell density of cultured bovine corneal endothelial cells can be varied from that found in the normal native cornea to that associated with corneal decompensation. In confluent cultures with cell densities ranging from 2750 cells/mm2 to 1000 cells/mm2, the number of pump sites per cell remains relatively unchanged. Below cell densities of 1000 cells/mm2, the number of pump sites per cell progressively increases. The increased Na pump site abundance in markedly hypertrophied endothelial cells cannot adequately compensate for the progressive reduction in the number of transporting cells per unit area within the intact monolayer. Even when considered with the decrease in the size of the paracellular ion conductive pathway that is a consequence of progressive endothelial hypertrophy, the overall pumping capacity of the intact endothelial monolayer declines.

SkQ1 Ophthalmic Solution for Dry Eye Treatment: Results of a Phase 2 Safety and Efficacy Clinical Study in the Environment and During Challenge in the Controlled Adverse Environment Model.

PubMed

Petrov, Anton; Perekhvatova, Natalia; Skulachev, Maxim; Stein, Linda; Ousler, George

2016-01-01

This Phase 2 clinical trial assessed the efficacy and safety of the novel antioxidative, renewable compound SkQ1 for topical treatment of dry eye signs and symptoms. In a single-center, randomized, double-masked, placebo-controlled, 29-day study, 91 subjects with mild to moderate dry eye instilled the study drug twice daily and recorded dry eye symptoms daily. Subjects were randomized 1:1:1 into one of three ophthalmic solution treatment groups: SkQ1 1.55 µg/mL, SkQ1 0.155 µg/mL, or 0.0 µg/mL (placebo). Subjects were exposed to a controlled adverse environment chamber at 3 of the 4 study visits (Day -7, Day 1, and Day 29). Investigator assessments occurred at all study visits. SkQ1 was safe and efficacious in treating dry eye signs and symptoms. Statistically significant improvements with SkQ1 compared to placebo occurred for the dry eye signs of corneal fluorescein staining and lissamine green staining in the central region and lid margin redness, and for the dry eye symptoms of ocular discomfort, dryness, and grittiness. In addition, SkQ1 demonstrated greater efficacy compared to placebo, although the differences were not statistically significant, for corneal fluorescein staining in other regions and/or time points (total staining score, central region, corneal sum score, and temporal region), lissamine green staining for the central and nasal regions, and blink rate scores. This Phase 2 study indicated that SkQ1 is safe and efficacious for the treatment of dry eye signs and symptoms and supported previous study results. Clinicaltrials.gov identifier: NCT02121301. Miotech S.A.

The evaluation of central corneal thickness and intraocular pressure in conjunction with tear IGF-1 levels in patients with acromegaly.

PubMed

Kan, Emrah; Kan, Elif K; Okuyucu, Ali

2017-08-30

To compare the central corneal thickness (CCT), intraocular pressure (IOP), and tear insulin-like growth factor 1 (IGF-1) levels between patients with acromegaly and a control group and to evaluate the possible effect of tear IGF-1 and duration of the disease on CCT and IOP. We included 31 patients with acromegaly (study group) and 40 age- and sex-matched controls in the study. Patients with acromegaly were divided into 2 subgroups based on disease status (active/inactive). All participants underwent complete ophthalmologic evaluation including CCT and IOP values. Basal tear samples were collected from both groups and tear IGF-1 levels were measured. The CCT, IOP, and tear IGF-1 levels were compared between groups and subgroups and the association between tear IGF-I levels and ocular parameters (CCT, IOP) and disease duration were also evaluated. Central corneal thickness, IOP, and tear IGF-1 levels did not show a significant difference between study and control groups. We also did not find a significant difference in terms of CCT, IOP, or tear IGF-1 levels between subgroups of patients. Correlation analysis did not show an association between the duration of disease and tear IGF-1 levels with CCT or IOP. There was no significant difference in tear IGF-1 levels between patients with acromegaly and controls. Additionally, there was no correlation between disease duration and tear IGF-1 levels with CCT or IOP levels. This lack of association may suggest that tear IGF-1 levels might not have an effect on CCT or IOP findings in patients with acromegaly.

Tissue and cellular biomechanics during corneal wound injury and repair.

PubMed

Raghunathan, Vijay Krishna; Thomasy, Sara M; Strøm, Peter; Yañez-Soto, Bernardo; Garland, Shaun P; Sermeno, Jasmyne; Reilly, Christopher M; Murphy, Christopher J

2017-08-01

Corneal wound healing is an enormously complex process that requires the simultaneous cellular integration of multiple soluble biochemical cues, as well as cellular responses to the intrinsic chemistry and biophysical attributes associated with the matrix of the wound space. Here, we document how the biomechanics of the corneal stroma are altered through the course of wound repair following keratoablative procedures in rabbits. Further we documented the influence that substrate stiffness has on stromal cell mechanics. Following corneal epithelial debridement, New Zealand white rabbits underwent phototherapeutic keratectomy (PTK) on the right eye (OD). Wound healing was monitored using advanced imaging modalities. Rabbits were euthanized and corneas were harvested at various time points following PTK. Tissues were characterized for biomechanics with atomic force microscopy and with histology to assess inflammation and fibrosis. Factor analysis was performed to determine any discernable patterns in wound healing parameters. The matrix associated with the wound space was stiffest at 7days post PTK. The greatest number of inflammatory cells were observed 3days after wounding. The highest number of myofibroblasts and the greatest degree of fibrosis occurred 21days after wounding. While all clinical parameters returned to normal values 400days after wounding, the elastic modulus remained greater than pre-surgical values. Factor analysis demonstrated dynamic remodeling of stroma occurs between days 10 and 42 during corneal stromal wound repair. Elastic modulus of the anterior corneal stroma is dramatically altered following PTK and its changes coincide initially with the development of edema and inflammation, and later with formation of stromal haze and population of the wound space with myofibroblasts. Factor analysis demonstrates strongest correlation between elastic modulus, myofibroblasts, fibrosis and stromal haze thickness, and between edema and central corneal thickness. Tissue biomechanics during the course of corneal wound healing is documented for the first time through atomic force microscopy, and is correlated with advanced clinical imaging and immunohistochemistry. Parameters obtained from the study are applied in a multivariate statistical model to cluster the data for better classification and monitor the wound repair process. Elastic modulus of the anterior corneal stroma is dramatically altered following wounding and correlates initially with the development of edema and inflammation, and later with formation of stromal haze and population of the wound space with myofibroblasts. Importantly, the occurrence of myofibroblasts is preceded by changes in tissue mechanics, which is important to consider in light of crosslinking procedures applied to treat corneal diseases. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

[Endothelial keratoplasty: Descemet stripping (DSEK) using TAN EndoGlide™ device: case series].

PubMed

Pazos, Henrique Santiago Baltar; Pazos, Paula Fernanda Morais Ramalho Baltar; Nogueira Filho, Pedro Antônio; Grisolia, Ana Beatriz Diniz; Silva, André Berger Emiliano; Gomes, José Álvaro Pereira

2011-01-01

To report the results of Descemet stripping endothelial keratoplasty (DSEK) using the TAN EndoGlideTM device to facilitate the insertion of the endothelial membrane. Prospective clinical study that included nine patients presenting corneal edema secondary to endothelial dysfunction. Best corrected visual acuity, refraction, central corneal thickness, endothelial cell density and complications were analyzed after a six-month follow-up. There was a significant improvement in the corneal edema and visual acuity in 7 patients (77.78%). The best corrected visual acuity ranged between 20/40 and 20/200. The average density of endothelial cells in six months varied between 1,305 cells/mm² and 2,346 cells/mm² with an average loss of 33.14% cells. Detachment of part of the graft was observed in one eye (11.11%) and primary failure of the endothelial transplantation occurred in 2 eyes (22.22%). The device TAN EndoGlideTM facilitates the introduction of the graft in Descemet stripping endothelial keratoplasty.

Topical anesthesia-induced keratopathy after laser-assisted subepithelial keratectomy.

PubMed

Rao, Srinivas K; Wong, Victoria W Y; Cheng, Arthur C K; Lam, Philip T H; Lam, Dennis S C

2007-08-01

A 42-year-old woman had uneventful bilateral laser-assisted subepithelial keratectomy (LASEK) to correct myopia. She experienced intense pain in the first postoperative week and obtained topical oxybuprocaine for pain relief. Subsequently, she developed bilateral persistent corneal epithelial defects, epithelial edema, and bullae that failed to heal with bandage contact lens and topical lubricants. Over the next 4 months, there was progressive corneal stromal thinning and descemetocele formation in 1 eye, requiring application of cyanoacrylate glue, and stromal edema and scarring in the other eye, which resulted in a visual acuity of counting fingers. Investigations did not reveal associated infection or an underlying immunological disorder; however, the patient admitted to excessive use of topical anesthetic eyedrops in the post-LASEK period. She subsequently had penetrating keratoplasty and lens extraction with IOL implantation in the right eye. The left eye healed with central corneal scarring. This case illustrates that serious sight-threatening complications may occur after LASEK due to abuse of topical anesthetic agents.

Second Harmonic Generation Imaging Analysis of Collagen Arrangement in Human Cornea.

PubMed

Park, Choul Yong; Lee, Jimmy K; Chuck, Roy S

2015-08-01

To describe the horizontal arrangement of human corneal collagen bundles by using second harmonic generation (SHG) imaging. Human corneas were imaged with an inverted two photon excitation fluorescence microscope. The excitation laser (Ti:Sapphire) was tuned to 850 nm. Backscatter signals of SHG were collected through a 425/30-nm bandpass emission filter. Multiple, consecutive, and overlapping image stacks (z-stacks) were acquired to generate three dimensional data sets. ImageJ software was used to analyze the arrangement pattern (irregularity) of collagen bundles at each image plane. Collagen bundles in the corneal lamellae demonstrated a complex layout merging and splitting within a single lamellar plane. The patterns were significantly different in the superficial and limbal cornea when compared with deep and central regions. Collagen bundles were smaller in the superficial layer and larger in deep lamellae. By using SHG imaging, the horizontal arrangement of corneal collagen bundles was elucidated at different depths and focal regions of the human cornea.

Comparison of central corneal thickness measurements with a rotating scheimpflug camera, a specular microscope, optical low-coherence reflectometry, and ultrasound pachymetry in keratoconic eyes.

PubMed

Cinar, Yasin; Cingu, Abdullah Kursat; Turkcu, Fatih Mehmet; Cinar, Tuba; Sahin, Alparslan; Yuksel, Harun; Ari, Seyhmus

2015-03-01

To compare central corneal thickness (CCT) measurements with a rotating Scheimpflug camera (RSC), noncontact specular microscopy (SM), optical low-coherence reflectometry (OLCR), and ultrasonic pachymetry (UP) in keratoconus (KC) patients. In this prospective study, four CCT measurements taken with an RSC, SM, OLCR, and UP were compared in 81 eyes of 44 consecutive KC patients. The KC patients were divided into four subgroups according to Amsler-Krumeich's KC classification. The RSC and UP measurements of the CCT were not statistically significant in all the groups. Comparison of the SM vs. the OLCR measurements yielded statistically significant differences in all the KC patients and in all KC stages. In all the KC patients, RSC and OLCR showed a high correlation coefficient factor (r = 0.87, p = 0.000). CCT measurements with RSC are comparable to those achieved with UP. Compared with the other devices, according to SM measurements, the central cornea is thicker in all keratoconic eyes and in all KC grades, and it is thinner according to OLCR. RSC, UP, SM, and OLCR should not be used interchangeably in keratoconic eyes.

Intergrin-dependent neutrophil migration in the injured mouse cornea

USDA-ARS?s Scientific Manuscript database

As an early responder to an inflammatory stimulus, neutrophils must exit the vasculature and migrate through the extravascular tissue to the site of insult, which is often remote from the point of extravasation. Following a central epithelial corneal abrasion, neutrophils recruited from the peripher...

Nocardia transvalensis keratitis: an emerging pathology among travelers returning from Asia.

PubMed

Trichet, Elodie; Cohen-Bacrie, Stéphan; Conrath, John; Drancourt, Michel; Hoffart, Louis

2011-10-31

The incidence rate of Nocardia keratitis is increasing, with new species identified thanks to molecular methods. We herein report a case of Nocardia transvalensis keratitis, illustrating this emerging pathology among travellers returning from Asia. A 23-year-old man presented with a 10-week history of ocular pain, redness, and blurred vision in his right eye following a projectile foreign body impacting the cornea while motor biking in Thaïland. At presentation, a central epithelial defect with a central whitish stromal infiltrate associated with pinhead satellite infiltrates was observed. Identification with 16S rRNA PCR sequencing and microbiological culture of corneal scraping and revealed N. transvalensis as the causative organism. Treatment was initiated with intensive topical amikacin, oral ketoconazole and oral doxycycline. After a four-week treatment period, the corneal infiltrate decreased so that only a faint subepithelial opacity remained. Nocardia organisms should be suspected as the causative agent of any case of keratitis in travelers returning from Asia. With appropriate therapy, Nocardia keratitis resolves, resulting in good visual outcome.

Optic disc size and other parameters from optical coherence tomography in Vietnamese-Americans.

PubMed

Peng, Pai-Huei; Fu, Sheena; Nguyen, Ngoc; Porco, Travis; Lin, Shan C

2011-08-01

To investigate the optic disc parameters by optical coherence tomography (OCT) in Vietnamese with various types of glaucoma. Medical charts of Vietnamese and White patients within a single practice were reviewed. Disc and rim areas by OCT were compared among nonglaucoma controls, different types of glaucoma, and glaucoma suspect. The association of these parameters with demographic and ocular features was evaluated. Data from 1416 Vietnamese and 57 White patients were included. A larger mean disc area was observed in eyes with primary angle-closure glaucoma than in eyes with primary angle-closure and primary angle-closure suspect (both P<0.001). There was no association between disc size with central corneal thickness (P=0.051) and sex (P=0.155). Vietnamese patients with glaucoma and glaucoma suspicion had larger discs than diagnosis-matched Whites (P=0.043 and 0.021, respectively). Vietnamese patients with glaucoma seem to have larger optic discs than White patients. Central corneal thickness had no association with disc area in this study population.

Translational Immunoimaging and Neuroimaging Demonstrate Corneal Neuroimmune Crosstalk.

PubMed

Hamrah, Pedram; Seyed-Razavi, Yashar; Yamaguchi, Takefumi

2016-11-01

Corneal immunoimaging and neuroimaging approaches facilitate in vivo analyses of the cornea, including high-resolution imaging of corneal immune cells and nerves. This approach facilitates the analyses of underlying immune and nerve alterations not detected by clinical slit-lamp examination alone. In this review, we describe recent work performed in our translational ocular immunology center with a focus on "bench-to-bedside" and "bedside-to-bench" research. The ability to visualize dendritiform immune cells (DCs) in patients with laser in vivo confocal microscopy (IVCM), recently discovered in the central murine cornea, has allowed us to demonstrate their utility as a potential surrogate biomarker for inflammatory ocular surface diseases. This biomarker for inflammation allows the measurement of therapeutic efficacy of anti-inflammatory drugs and its utility as an endpoint in clinical trials with high interobserver agreement. IVCM image analyses from our studies has demonstrated a significant increase in DC density and size in ocular disease, a positive correlation between DC density and clinical signs and symptoms of disease and pro-inflammatory tear cytokines, and a strong negative correlation between DC density and subbasal nerve density. In conjunction with preclinical research investigating the inflammatory state in a partial or fully denervated cornea, our results indicated that corneal nerves are directly involved in the regulation of homeostasis and immune privilege in the cornea.

Laser thermokeratoplasty after lamellar corneal cutting.

PubMed

Ismail, M M; Pérez-Santonja, J J; Alió, J L

1999-02-01

To evaluate the effect of laser thermokeratoplasty (LTK) in eyes that previously had a lamellar corneal cut. University of Al-Azhar, Cairo, Egypt, and Instituto Oftalmológico de Alicante, Spain. In 15 eyes (10 patients), noncontact LTK was applied 6 to 8 weeks after a lamellar corneal cut had been made. Central pachymetry, keratometry, and videokeratography were performed and uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), and manifest and cycloplegic refractions measured before and 1, 6, 12, and 18 months after LTK. Mean follow-up was 19.13 months. Mean refraction was +5.93 diopters (D) +/- 1.9 (SD) before LTK and -0.43 +/- 1.5 D at 1 month, +1.63 +/- 1.6 D at 6 months, 1.91 +/- 1.41 at 12 months, and +2.01 +/- 1.5 D at the end of the study. Total regression did not occur in any case. Mean BSCVA before LTK was 0.66 +/- 0.2, and spontaneous visual acuity at the end of the study was 0.58 +/- 0.18. No patient lost any lines of preoperative BSCVA. There was no significant difference between the results at 12 months and at the end of the study. Corneal lamellar cutting appeared to improve the magnitude of the refractive effect of noncontact LTK and to decrease the amount of regression.

Phase 2 Randomized, Double-Masked, Vehicle-Controlled Trial of Recombinant Human Nerve Growth Factor for Neurotrophic Keratitis.

PubMed

Bonini, Stefano; Lambiase, Alessandro; Rama, Paolo; Sinigaglia, Francesco; Allegretti, Marcello; Chao, Wendy; Mantelli, Flavio

2018-04-10

To evaluate the safety and efficacy of topical recombinant human nerve growth factor (rhNGF) for treating moderate-to-severe neurotrophic keratitis (NK), a rare degenerative corneal disease resulting from impaired corneal innervation. Phase 2 multicenter, randomized, double-masked, vehicle-controlled trial. Patients with stage 2 (moderate) or stage 3 (severe) NK in 1 eye. The REPARO phase 2 study assessed safety and efficacy in 156 patients randomized 1:1:1 to rhNGF 10 μg/ml, 20 μg/ml, or vehicle. Treatment was administered 6 drops per day for 8 weeks. Patients then entered a 48- or 56-week follow-up period. Safety was assessed in all patients who received study treatment, whereas efficacy was by intention to treat. Corneal healing (defined as <0.5-mm maximum diameter of fluorescein staining in the lesion area) was assessed by masked central readers at week 4 (primary efficacy end point) and week 8 (key secondary end point) of controlled treatment. Corneal healing was reassessed post hoc by masked central readers using a more conservative measure (0-mm staining in the lesion area and no other persistent staining). At week 4 (primary end point), 19.6% of vehicle-treated patients achieved corneal healing (<0.5-mm lesion staining) versus 54.9% receiving rhNGF 10 μg/ml (+35.3%; 97.06% confidence interval [CI], 15.88-54.71; P < 0.001) and 58.0% receiving rhNGF 20 μg/ml (+38.4%; 97.06% CI, 18.96-57.83; P < 0.001). At week 8 (key secondary end point), 43.1% of vehicle-treated patients achieved less than 0.5-mm lesion staining versus 74.5% receiving rhNGF 10 μg/ml (+31.4%; 97.06% CI, 11.25-51.49; P = 0.001) and 74.0% receiving rhNGF 20 μg/ml (+30.9%; 97.06% CI, 10.60-51.13; P = 0.002). Post hoc analysis of corneal healing by the more conservative measure (0-mm lesion staining and no other persistent staining) maintained statistically significant differences between rhNGF and vehicle at weeks 4 and 8. More than 96% of patients who healed after controlled rhNGF treatment remained recurrence free during follow-up. Treatment with rhNGF was well tolerated; adverse effects were mostly local, mild, and transient. Topical rhNGF is safe and more effective than vehicle in promoting healing of moderate-to-severe NK. Copyright © 2018 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Assessment and diagnosis of suspected glaucoma in patients with mucopolysaccharidosis.

PubMed

Ashworth, Jane; Flaherty, Maree; Pitz, Susanne; Ramlee, Azura

2015-03-01

The mucopolysaccharidoses (MPS) are a group of rare lysosomal storage disorders, characterized by the accumulation of glycosaminoglycans within multiple organ systems including the eye. This study aimed to determine the prevalence of glaucoma in patients with MPS, as well as the characteristics, diagnosis and management of patients with MPS and glaucoma. A multicentre retrospective case-note review was carried out by ophthalmologists from four tertiary referral centres to identify patients with MPS who had been treated for glaucoma. Clinical ophthalmological data were collected using standardized data collection forms. Fourteen patients were identified (27 eyes) of 294 patients with MPS. The prevalence of glaucoma ranged from 2.1% to 12.5%. The median age at diagnosis of glaucoma was 8 years. Diagnostic evaluation of glaucoma was incomplete in many patients: intraocular pressure was documented in all eyes, but optic disc appearance was only assessed in 67%, central corneal thickness in 26%, visual fields in 19% and iridocorneal angle in 15%. Patients with MPS need regular assessment for possible glaucoma including during childhood. Multiple factors contribute to the challenges of assessment, diagnosis and monitoring of glaucoma in these patients. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Refractive Errors in Patients with Migraine Headache.

PubMed

Gunes, Alime; Demirci, Seden; Tok, Levent; Tok, Ozlem; Koyuncuoglu, Hasan; Yurekli, Vedat Ali

2016-01-01

To evaluate refractive errors in patients with migraine headache and to compare with healthy subjects. This prospective case-control study includes patients with migraine and age- and sex-matched healthy subjects. Clinical and demographic characteristics of the patients were noted. Detailed ophthalmological examinations were performed containing spherical refractive error, astigmatic refractive error, spherical equivalent (SE), anisometropia, best-corrected visual acuity, intraocular pressure, slit lamp biomicroscopy, fundus examination, axial length, anterior chamber depth, and central corneal thickness. Spectacle use in migraine and control groups was compared. Also, the relationship between refractive components and migraine headache variables was investigated. Seventy-seven migraine patients with mean age of 33.27 ± 8.84 years and 71 healthy subjects with mean age of 31.15 ± 10.45 years were enrolled (p = 0.18). The migraine patients had higher degrees of astigmatic refractive error, SE, and anisometropia when compared with the control subjects (p = 0.01, p = 0.03, p = 0.02, respectively). Migraine patients may have higher degrees of astigmatism, SE, and anisometropia. Therefore, they should have ophthalmological examinations regularly to ensure that their refractive errors are appropriately corrected.

Comparative Toxicity of Preservatives on Immortalized Corneal and Conjunctival Epithelial Cells

PubMed Central

Ahdoot, Michael; Marcus, Edward; Asbell, Penny A.

2009-01-01

Abstract Purpose Nearly all eye drops contain preservatives to decrease contamination. Nonpreservatives such as disodium-ethylene diamine tetra-acetate (EDTA) and phosphate-buffered saline are also regularly added as buffering agents. These components can add to the toxicity of eye drops and cause ocular surface disease. To evaluate the potential toxicity of these common components and their comparative effects on the ocular surface, a tissue culture model utilizing immortalized corneal and conjunctival epithelial cells was utilized. Methods Immortalized human conjunctival and corneal epithelial cells were grown. At confluency, medium was replaced with 100 μL of varying concentrations of preservatives: benzalkonium chloride (BAK), methyl paraben (MP), sodium perborate (SP), chlorobutanol (Cbl), and stabilized thimerosal (Thi); varying concentrations of buffer: EDTA; media (viable control); and formalin (dead control). After 1 h, solutions were replaced with 150 μL of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazonium bromide). After 4 h, solutions decanted, 100 μL of acid isopropanol added, and the optical density determined at 572 nm to evaluate cell viability. Results Conjunctival and corneal cell toxicity was seen with all preservatives. Depending upon concentration, BAK exhibited from 56% to 89% toxicity. In comparison, Cbl exhibited from 50% to 86%, MP from 30% to 76%, SP from 23% to 59%, and Thi from 70% to 95%. EDTA with minimal toxicity (from 6% to 59%) was indistinguishable from SP. Conclusions Generally, the order of decreasing toxicity at the most commonly used concentrations: Thi (0.0025%) > BAK (0.025%) > Cbl (0.25%) > MP (0.01%) > SP (0.0025%) ≈ EDTA (0.01%). Even at low concentration, these agents will cause some degree of ocular tissue damage. PMID:19284328

Topical non-steroidal anti-inflammatory drugs for analgesia in traumatic corneal abrasions.

PubMed

Wakai, Abel; Lawrenson, John G; Lawrenson, Annali L; Wang, Yongjun; Brown, Michael D; Quirke, Michael; Ghandour, Omar; McCormick, Ryan; Walsh, Cathal D; Amayem, Ahmed; Lang, Eddy; Harrison, Nick

2017-05-18

Traumatic corneal abrasions are relatively common and there is a lack of consensus about analgesia in their management. It is therefore important to document the clinical efficacy and safety profile of topical ophthalmic non-steroidal anti-inflammatory drugs (NSAIDs) in the management of traumatic corneal abrasions. To identify and evaluate all randomised controlled trials (RCTs) comparing the use of topical NSAIDs with placebo or any alternative analgesic interventions in adults with traumatic corneal abrasions (including corneal abrasions arising from foreign body removal), to reduce pain, and its effects on healing time. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 2), MEDLINE Ovid (1946 to 30 March 2017), Embase Ovid (1947 to 30 March 2017), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 30 March 2017), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/); searched 30 March 2017, ZETOC (1993 to 30 March 2017), the ISRCTN registry (www.isrctn.com/editAdvancedSearch); searched 30 March 2017, ClinicalTrials.gov (www.clinicaltrials.gov); searched 30 March 2017 and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 30 March 2017. We did not use any date or language restrictions in the electronic searches for trials.We checked the reference lists of identified trials to search for further potentially relevant studies. RCTs comparing topical NSAIDs to placebo or any alternative analgesic interventions in adults with traumatic corneal abrasions. Two review authors independently performed data extraction and assessed risks of bias in the included studies. We rated the certainty of the evidence using GRADE. We included nine studies that met the inclusion criteria, reporting data on 637 participants.The studies took place in the UK, USA, Israel, Italy, France and Portugal. These studies compared five types of topical NSAIDs (0.1% indomethacin, 0.03% flurbiprofen, 0.5% ketorolac, 1% indomethacin, 0.1% diclofenac) to control (consisting of standard care and in four studies used placebo eye drops). Overall, the studies were at an unclear or high risk of bias (particularly selection and reporting bias). None of the included studies reported the primary outcome measures of this review, namely participant-reported pain intensity reduction of 30% or more or 50% or more at 24 hours. Four trials, that included data on 481 participants receiving NSAIDs or control (placebo/standard care), reported on the use of 'rescue' analgesia at 24 hours as a proxy measure of pain control. Topical NSAIDs were associated with a reduction in the need for oral analgesia compared with control (risk ratio (RR) 0.46, 95% confidence interval (CI) 0.34 to 0.61; low-certainty evidence). Approximately 4 out of 10 people in the control group used rescue analgesia at 24 hours. No data were available on the use of analgesia at 48 or 72 hours.One trial (28 participants) reported on the proportion of abrasions healed after 24 and 48 hours. These outcomes were similar in both arms of the trial. (at 24 hours RR 1.00 (0.81 to 1.23); at 48 hours RR 1.00 (0.88 to 1.14); low-certainty evidence). In the control group nine out of 10 abrasions were healed within 24 hours and all were healed by 48 hours. Complications of corneal abrasions were reported in 6 studies (609 participants) and were infrequently reported (4 complications, 1 in NSAID groups (recurrent corneal erosion) and 3 in control groups (2 recurrent corneal erosions and 1 corneal abscess), very low-certainty evidence). Possible drug-related adverse events (AEs) were reported in two trials (163 participants), with the number of adverse events low (4 AEs, 3 in NSAID group, including discomfort/photophobia on instillation, conjunctival hyperaemia and urticaria, and 1 in the control group, corneal abscess) very low-certainty evidence. The findings of the included studies do not provide strong evidence to support the use of topical NSAIDs in traumatic corneal abrasions. This is important, since NSAIDs are associated with a higher cost compared to oral analgesics. None of the trials addressed our primary outcome measure of participant-reported pain intensity reduction of 30% or more or 50% or more at 24 hours.

Uneventful Anterior Migration of Intravitreal Ozurdex Implant in a Patient with Iris-Sutured Intraocular Lens and Descemet Stripping Automated Endothelial Keratoplasty.

PubMed

Zafar, Andleeb; Aslanides, Ioannis M; Selimis, Vasileios; Tsoulnaras, Konstantinos I; Tabibian, David; Kymionis, George D

2018-01-01

We report here the case of a patient with anterior segment migration of intravitreal dexamethasone implant as well as its management and outcome. The patient had the following sequence of events: complicated cataract surgery, iris-sutured intraocular lens implant, followed by cystoid macular edema treated with intravitreal Avastin, retinal vein occlusion treated with intravitreal dexamethasone implant, corneal decompensation treated with Descemet stripping automated endothelial keratoplasty (DSAEK), and finally recurrence of macular edema treated with repeated intravitreal dexamethasone implant. Dexamethasone implant had completely dissolved from the eye 12 weeks after insertion without any complication. A conservative approach with regular monitoring in the situation of a quiet anterior segment without any corneal decompensation can provide enough time for the implant to dissolve without causing any complication to the involved eye, avoiding any additional surgical intervention, as presented in this case report. Despite the fact that the implant was left for natural dissolution, there were no adverse effects related to the graft or the eye.

Cataract surgery in eyes with low corneal endothelial cell density.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Manabe, Shin-ichi; Hirata, Akira

2011-08-01

To compare corneal endothelial damage after cataract surgery in eyes with low endothelial cell density (ECD) and eyes with normal ECD. Hayashi Eye Hospital, Fukuoka, Japan. Case-control study. Cataract surgery was performed in eyes with a low ECD (500 to 1000 cells/mm(2)) (low-density group) and control eyes with a normal ECD. The ECD and central corneal thickness (CCT) were measured preoperatively and 1 and 3 months postoperatively, and the percentage cell loss and increase in CCT were compared. The low-density group and control group each comprised 50 eyes. In the low-density group, 39 eyes had nonprogressive endothelial pathology and 11 had Fuchs dystrophy. The mean ECD was significantly less and the CCT significantly greater in the low-density group than in the control group throughout the follow-up (P ≤.0066). However, no significant difference in the percentage of cell loss was found between groups at 1 or 3 months (5.1%, low-density group; 4.2%, control group) (P ≥.1477). The percentage increase in CCT was significantly greater in the low-density group than in the control group at 1 month (P<.0001), although there was no significant difference at 3 months (0.4% and -0.4%, respectively) (P=.2172). Corneal endothelial damage after cataract surgery in eyes with low ECD was slight and comparable to that in healthy eyes, which suggests that cataract surgery alone (without corneal transplantation) should be performed first. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Keratoconus in Civil Aviation Pilots in a Report of Six Cases.

PubMed

Rebello, Albert; Rodrigues, Bênesson; Pereira, Marcos

2017-06-01

Keratoconus is a progressive noninflammatory ectatic corneal dystrophy, characterized by corneal thinning and increased curvature with central or paracentral tapered protrusion. Such changes in corneal morphology induce irregular astigmatism and myopia, resulting in visual acuity impairment. This report assesses cases in which keratoconus is not an absolute disabling condition for civil aviation pilots. Six cases of keratoconus in active pilots are presented. This report includes cases which were treated with crosslinking therapy and even corneal transplantation. In such cases, the civil aviation medical authority considered four aspects in the medical assessment: best corrected visual acuity, condition stability, risk of sudden incapacitation, and pilot category. Six civil pilots with ages between 19 and 45 yr of age presented with keratoconus in different stages. Using the Snellen scale, best corrected visual acuity (BCVA) was measured in 12 eyes, all of them having equal or better than 20/30 (20/20, N = 9; 20/25, N = 2; 20/30, N = 1). All of them are currently fit for aviation activity and have been given an aviation medical certificate with limitation of use of corrective lenses by the Brazilian Civil Aviation Authority (ANAC in Portuguese). Among these cases, there is a pilot who had undergone treatment with crosslinking therapy and another that had undergone corneal transplantation. These cases demonstrate that keratoconus is not always a disabling condition for civil aviation pilots. Nevertheless, it has to be analyzed on a case-by-case basis.Rebello A, Rodrigues B, Pereira M. Keratoconus in civil aviation pilots in a report of six cases. Aerosp Med Hum Perform. 2017; 88(6):574-578.

In vivo laser confocal microscopy findings of a cornea with osteogenesis imperfecta

PubMed Central

Kobayashi, Akira; Higashide, Tomomi; Yokogawa, Hideaki; Yamazaki, Natsuko; Masaki, Toshinori; Sugiyama, Kazuhisa

2014-01-01

Objective To report the in vivo laser confocal microscopy findings of a cornea with osteogenesis imperfecta (OI) with special attention to the abnormality of Bowman’s layer and sub-Bowman’s fibrous structures (K-structures). Patients and methods Two patients (67-year-old male and his 26-year-old son) with OI type I were included in this study. Slit lamp biomicroscopic and in vivo laser confocal microscopic examinations were performed for both patients. Central corneal thickness and central endothelial cell density were also measured. Results Although the corneas looked clear with normal endothelial density for both eyes in both patients, they were quite thin (386 μm oculus dexter (OD) (the right eye) and 384 μm oculus sinister (OS) (the left eye) in the father and 430 μm OD and 425 μm OS in the son). In both patients, slit lamp biomicroscopic and in vivo laser confocal microscopic examination showed similar results. Anterior corneal mosaics produced by rubbing the eyelid under fluorescein were completely absent in both eyes. In vivo laser confocal microscopy revealed an absent or atrophic Bowman’s layer; a trace of a presumed Bowman’s layer and/or basement membrane was barely visible with high intensity. Additionally, K-structures were completely absent in both eyes. Conclusion The absence of K-structures and fluorescein anterior corneal mosaics strongly suggested an abnormality of Bowman’s layer in these OI patients. PMID:24591812

Interventions for recurrent corneal erosions.

PubMed

Watson, Stephanie L; Lee, Ming-Han H; Barker, Nigel H

2012-09-12

Recurrent corneal erosion is a common cause of disabling ocular symptoms and predisposes the cornea to infection. It may follow corneal trauma. Measures to prevent the development of recurrent corneal erosion following corneal trauma have not been firmly established. Once recurrent corneal erosion develops simple medical therapy (standard treatment) may lead to resolution of the episode. However, some patients continue to suffer when such therapy fails and once resolved further episodes of recurrent erosion may occur. A number of treatment and prophylactic options are then available but there is no agreement as to the best option. To assess the effectiveness and safety of prophylactic and treatment regimens for recurrent corneal erosion. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 6), MEDLINE (January 1946 to June 2012), EMBASE (January 1980 to June 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 13 June 2012. We also contacted researchers in the field. We included randomised and quasi-randomised trials that compared a prophylactic or treatment regimen with another prophylaxis/treatment or no prophylaxis/treatment for patients with recurrent corneal erosion. Two authors independently extracted data and assessed trial quality. We contacted study authors for additional information. Seven randomised and one quasi-randomised controlled trial were included in the review. The trials were heterogenous and of poor quality. Safety data presented were incomplete. For the treatment of recurrent corneal erosion, a single-centre trial in the UK with 30 participants showed that oral tetracycline 250 mg twice daily for 12 weeks or topical prednisolone 0.5% four times daily for one week, or both, in addition to standard treatment, accelerated healing rates and improved symptoms. A single-centre trial in Sweden with 56 participants showed that excimer laser ablation in addition to mechanical debridement may reduce the number of erosions and improve symptoms. Furthermore, in a single-centre trial in Germany with 100 participants, transepithelial technique for excimer laser ablation had the same efficacy as the traditional subepithelial excimer laser technique but caused less pain. In a small study of 24 participants in UK, therapeutic contact lens wear was inferior to lubricant drops and ointment in abolishing the symptoms of recurrent corneal erosion and had a high complication rate, although the contact lenses used were the older generation with low oxygen permeability. A recent study in Hong Kong with 48 participants found diamond burr polishing to reduce episodes of recurrent corneal erosion. For prophylaxis of further episodes of recurrent corneal erosion, there was no difference in the occurrence of objective signs of recurrent erosion between hypertonic saline ointment versus tetracycline ointment or lubricating ointment in a small Japanese study with 26 participants. Also, in a single-centre study in the UK with 117 participants, there was no difference in symptom improvement between hypertonic saline versus paraffin ointment when used for prophylaxis. In a UK study with 42 participants, lubricating ointment at night in addition to standard treatment to prevent recurrence following traumatic corneal abrasion (erosion) caused by fingernail injury led to increased symptoms of recurrent corneal erosion compared to standard therapy alone. Well-designed, masked, randomised controlled trials using standardised methods are needed to establish the benefits of new and existing prophylactic and treatment regimes for recurrent corneal erosion. International consensus is also needed to progress research efforts towards evaluation of the major effective treatments for recurrent corneal erosions.

The Palisades of Vogt in Congenital Corneal Opacification (An American Ophthalmological Society Thesis).

PubMed

Nischal, Ken K; Lathrop, Kira L

2016-08-01

The purposes of this study are first, to determine if the palisades of Vogt (POV) are present or absent in cases of congenital corneal opacification (CCO) by using spectral domain ocular coherence tomography (SD-OCT), and second, in those cases already undergoing penetrating keratoplasty (PKP), to see whether the absence or presence of POV corresponds to re-epithelialization following transplant. This was a retrospective case review of 20 eyes (10 normal, 10 with CCO) evaluated with SD-OCT. The operator was masked to the clinician's assessment of the ocular surface. In those cases where the decision to perform PKP had already been made, the correlation between POV presence or absence and posttransplant graft epithelialization was determined. All cases were imaged without adverse event. Nine eyes showed some evidence of POV and corresponding vasculature. Eight of 10 affected eyes underwent PKP, and subsequently 7 eyes epithelialized and 2 showed some peripheral neovascularization. The one eye that showed no signs of POV was the one that failed to epithelialize. All control subjects had consistent and regular POV. Congenital corneal opacification is rare, and this study shows that at least some POV are present in the majority of cases of CCO. However, the palisades may not be entirely normal compared to age-matched controls. When there was absence of POV in a case of CCO, there was immediate and complete failure of epithelialization.

Longitudinal Evaluation of Cornea With Swept-Source Optical Coherence Tomography and Scheimpflug Imaging Before and After Lasik

PubMed Central

Chan, Tommy C.Y.; Biswas, Sayantan; Yu, Marco; Jhanji, Vishal

2015-01-01

Abstract Swept-source optical coherence tomography (OCT) is the latest advancement in anterior segment imaging. There are limited data regarding its performance after laser in situ keratomileusis (LASIK). We compared the reliability of swept-source OCT and Scheimpflug imaging for evaluation of corneal parameters in refractive surgery candidates with myopia or myopic astigmatism. Three consecutive measurements were obtained preoperatively and 1 year postoperatively using swept-source OCT and Scheimpflug imaging. The study parameters included central corneal thickness (CCT), thinnest corneal thickness (TCT), keratometry at steep (Ks) and flat (Kf) axes, mean keratometry (Km), and, anterior and posterior best fit spheres (Ant and Post BFS). The main outcome measures included reliability of measurements before and after LASIK was evaluated using intraclass correlation coefficient (ICC) and reproducibility coefficients (RC). Association between the mean value of corneal parameters with age, spherical equivalent (SEQ), and residual bed thickness (RBT) and association of variance heterogeneity of corneal parameters and these covariates were analyzed. Twenty-six right eyes of 26 participants (mean age, 32.7 ± 6.9 yrs; mean SEQ, −6.27 ± 1.67 D) were included. Preoperatively, swept-source OCT demonstrated significantly higher ICC for Ks, CCT, TCT, and Post BFS (P ≤ 0.016), compared with Scheimpflug imaging. Swept-source OCT demonstrated significantly smaller RC values for CCT, TCT, and Post BFS (P ≤ 0.001). After LASIK, both devices had significant differences in measurements for all corneal parameters (P ≤ 0.015). Swept-source OCT demonstrated a significantly higher ICC and smaller RC for all measurements, compared with Scheimpflug imaging (P ≤ 0.001). Association of variance heterogeneity was only found in pre-LASIK Ant BFS and post-LASIK Post BFS for swept-source OCT, whereas significant association of variance heterogeneity was noted for all measurements except Ks and Km for Scheimpflug imaging. This study reported higher reliability of swept-source OCT for post-LASIK corneal measurements, as compared with Scheimpflug imaging. The reliability of corneal parameters measured with Scheimpflug imaging after LASIK was not consistent across different age, SEQ, and RBT measurements. These factors need to be considered during follow-up and evaluation of post-LASIK patients for further surgical procedures. PMID:26222852

Acute hypoxia influences collagen and matrix metalloproteinase expression by human keratoconus cells in vitro.

PubMed

McKay, Tina B; Hjortdal, Jesper; Priyadarsini, Shrestha; Karamichos, Dimitrios

2017-01-01

Keratoconus (KC) is a progressive corneal ectasia linked to thinning of the central cornea. Hard contact lenses, rigid gas permeable lenses, and scleral lenses are the primary treatment modalities for early to mid- stages of KC to correct refractive error and astigmatism that develops as a result of an irregular corneal structure. These treatments are associated with significant drawbacks, including reduced availability of the tear film and oxygen to the corneal epithelium and stroma. However, it remains unknown whether hypoxia affects corneal integrity in the KC pathobiology. A number of studies have associated elevated oxidative stress with KC both in vitro and ex vivo. We hypothesized that KC-derived corneal fibroblasts are more susceptible to hypoxia-induced oxidative stress compared to healthy controls leading to exacerbation of corneal thinning in KC. This study investigated the effects of hypoxia on ECM secretion, assembly, and matrix metalloproteinase (MMP) expression in human corneal fibroblasts from healthy controls (HCFs) and KC patients (HKCs) in vitro. HCFs and HKCs were cultured in 3D constructs for 3 weeks and maintained or transferred to normoxic (21% O2) or hypoxic (2% O2) conditions, respectively, for 1 additional week. At the 4 week time-point, constructs were isolated and probed for Collagen I, III, and V, keratocan and MMP-1, -2, -3, -9, and -13, as well as hypoxia markers, hypoxia inducible factor-1α and lactoferrin. Conditioned media was also collected and probed for Collagen I, III, and V by Western blot. Thickness of the ECM assembled by HCFs and HKCs was measured using immunofluorescence microscopy. Results showed that hypoxia significantly reduced Collagen I secretion in HKCs, as well as upregulated the expression of MMP-1 and -2 with no significant effects on MMP-3, -9, or -13. ECM thickness was reduced in both cell types following 1 week in a low oxygen environment. Our study shows that hypoxia influences collagen and MMP expression by HKCs, which may have consequential effects on ECM structure in the context of KC.

In-vivo corneal pulsation in relation to in-vivo intraocular pressure and corneal biomechanics assessed in-vitro. An animal pilot study.

PubMed

Rogala, Maja M; Danielewska, Monika E; Antończyk, Agnieszka; Kiełbowicz, Zdzisław; Rogowska, Marta E; Kozuń, Marta; Detyna, Jerzy; Iskander, D Robert

2017-09-01

The aim was to ascertain whether the characteristics of the corneal pulse (CP) measured in-vivo in a rabbit eye change after short-term artificial increase of intraocular pressure (IOP) and whether they correlate with corneal biomechanics assessed in-vitro. Eight New Zealand white rabbits were included in this study and were anesthetized. In-vivo experiments included simultaneous measurements of the CP signal, registered with a non-contact method, IOP, intra-arterial blood pressure, and blood pulse (BPL), at the baseline and short-term elevated IOP. Afterwards, thickness of post-mortem corneas was determined and then uniaxial tensile tests were conducted leading to estimates of their Young's modulus (E). At the baseline IOP, backward stepwise regression analyses were performed in which successively the ocular biomechanical, biometric and cardiovascular predictors were separately taken into account. Results of the analysis revealed that the 3rd CP harmonic can be statistically significantly predicted by E and central corneal thickness (Models: R 2  = 0.662, p < 0.005 and R 2  = 0.832, p < 0.001 for the signal amplitude and power, respectively). The 1st CP harmonic can be statistically significantly predicted by the amplitude and power of the 1st BPL harmonic (Models: R 2  = 0.534, p = 0.015 and R 2  = 0.509, p < 0.018, respectively). For elevated IOP, non-parametric analysis indicated significant differences for the power of the 1st CP harmonic (Kruskal-Wallis test; p = 0.031) and for the mean, systolic and diastolic blood pressures (p = 0.025, p = 0.019, p = 0.033, respectively). In conclusion, for the first time, the association between parameters of the CP signal in-vivo and corneal biomechanics in-vitro was confirmed. In particular, spectral analysis revealed that higher amplitude and power of the 3rd CP harmonic indicates higher corneal stiffness, while the 1st CP harmonic correlates positively with the corresponding harmonic of the BPL signal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silicone hydrogel mini-scleral contact lenses in early stage after corneal collagen cross-linking for keratoconus: a retrospective case series.

PubMed

Severinsky, Boris; Wajnsztajn, Denise; Frucht-Pery, Joseph

2013-11-01

 The aim was to the evaluate performance of a novel silicone hydrogel mini-scleral contact lens (SHmS) for optical correction of keratoconus in the early stages after the corneal collagen cross-linking procedure (CXL).  We retrospectively analysed the visual acuity improvement and corneal adaptation in the first 10 eyes of nine patients fitted with SHmS lenses one to 3.5 months after corneal collagen cross-linking. The lenses were designed to rest over the patients' sclera and peri-limbal cornea and vault the central cornea with minimal support over it. Visual acuities with manifest refraction and contact lenses, refractive and topographical values (Kmin and Kmax) were evaluated on lens dispensing and after six month of lens wearing. Ocular physiological responses were evaluated using the Institute of Eye Research (IER) grading scales.  SHmS fitting was performed 2.1 ± 0.97 (SD) months after collagen cross-linking. Mean follow up was 10.9 ± 4.41 months (range six to 18 months). Mean decimal visual acuity with SHmS was 0.66 ± 0.22 (approximately 6/9 Snellen fraction, range 0.3 to 0.1) or 0.75 ± 0.14 (approximately 6/8.1, range 0.5 to 1.0), when omitting two amblyopic eyes. Nine (90 per cent) eyes were successfully fitted, that is, able to wear the lenses for 10 hours per day or longer. Mean wearing time was 11.7 hours (range six to 14) per day. No corneal neovascularisation or papillary reaction was found in all fitted eyes.  SHmS contact lenses provide successful visual rehabilitation shortly after corneal collagen cross-linking. This new soft contact lens design with scleral fixation and minimal apical touch was demonstrated to be safe shortly after collagen cross-linking, as the avoidance of contact with the treated zone minimises contact lens influence on corneal recovery. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

Delay of corneal epithelial wound healing and induction of keratocyte apoptosis by platelet-activating factor.

PubMed

Chandrasekher, Gudiseva; Ma, Xiang; Lallier, Thomas E; Bazan, Haydee E P

2002-05-01

To examine the role of the lipid mediator platelet-activating factor (PAF) in epithelial wound healing. A 7-mm central de-epithelializing wound was produced in rabbit corneas, and the tissue was incubated with 125 nM carbamyl PAF (cPAF), an analogue of PAF. Rabbit corneal epithelial and stromal cells were also cultured in the presence of cPAF. Cell adhesion, proliferation, and migration assays were conducted. Apoptosis was assayed by TUNEL staining on preparations of corneal tissue sections and in cells in culture. Twenty-four hours after injury, 50% of the wounded area was covered by new epithelium, whereas only 30% was covered in the presence of cPAF. At 48 hours, the epithelium completely closed the wound, but only 45% of the original wound was covered in corneas treated with cPAF. Similar inhibition of epithelial wound closure was found with human corneas incubated with PAF in organ culture. Moreover, addition of several growth factors involved in corneal wound healing, such as epidermal growth factor, hepatocyte growth factor, and keratinocyte growth factor, could not overcome the inhibitory action of PAF in wound closure. Three PAF antagonists, BN50727, BN50730, and BN50739, abolished the effect of PAF. A significant increase in TUNEL-positive staining occurred in corneal stromal cells (keratocytes), which was inhibited by preincubating the corneas with PAF antagonists. However, no TUNEL-positive staining was found in epithelial cells. TUNEL-staining results in cultured stromal cells (keratocytes) and epithelial cells in first-passage cell culture were similar to those in organ-cultured corneas. In addition, PAF caused 35% to 56% inhibition of adhesion of epithelial cells to proteins of the extracellular matrix: collagen I and IV, fibronectin, and laminin. There were no significant changes in proliferation or migration of epithelial cells induced by the lipid mediator. The results suggest PAF plays an important role in preventing corneal wound healing by affecting adhesion of epithelial cells and increasing apoptosis in stromal cells. PAF antagonists could be of therapeutic importance during prolonged ocular inflammation, helping to avoid loss of corneal transparency and visual acuity.

Simultaneous versus sequential penetrating keratoplasty and cataract surgery.

PubMed

Hayashi, Ken; Hayashi, Hideyuki

2006-10-01

To compare the surgical outcomes of simultaneous penetrating keratoplasty and cataract surgery with those of sequential surgery. Thirty-nine eyes of 39 patients scheduled for simultaneous keratoplasty and cataract surgery and 23 eyes of 23 patients scheduled for sequential keratoplasty and secondary phacoemulsification surgery were recruited. Refractive error, regular and irregular corneal astigmatism determined by Fourier analysis, and endothelial cell loss were studied at 1 week and 3, 6, and 12 months after combined surgery in the simultaneous surgery group or after subsequent phacoemulsification surgery in the sequential surgery group. At 3 and more months after surgery, mean refractive error was significantly greater in the simultaneous surgery group than in the sequential surgery group, although no difference was seen at 1 week. The refractive error at 12 months was within 2 D of that targeted in 15 eyes (39%) in the simultaneous surgery group and within 2 D in 16 eyes (70%) in the sequential surgery group; the incidence was significantly greater in the sequential group (P = 0.0344). The regular and irregular astigmatism was not significantly different between the groups at 3 and more months after surgery. No significant difference was also found in the percentage of endothelial cell loss between the groups. Although corneal astigmatism and endothelial cell loss were not different, refractive error from target refraction was greater after simultaneous keratoplasty and cataract surgery than after sequential surgery, indicating a better outcome after sequential surgery than after simultaneous surgery.

Safety of intracameral injection of gatifloxacin, levofloxacin on corneal endothelial structure and viability.

PubMed

Choi, Jin A; Chung, Sung Kun

2009-10-01

To investigate the safety of intracameral injection of gatifloxacin, levofloxacin in a rabbit model as prophylaxis against endophthalmitis. Twenty-four eyes of New Zealand white rabbits were randomly divided into 3 treatment groups: levofloxacin, gatifloxacin, and balanced salt solution (BSS) control groups. After 100 microL of each was injected into the anterior chamber, endothelial toxicity was evaluated by measuring the central corneal thicknesses and the clinical toxicity scores using a slit-lamp at post-procedure days 3 and 7. The percent of dead cells was determined by vital staining with alizarin red and trypan blue at 7 days after injection. Finally, in each group, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed for the evaluation of structural integrity. The toxicity scores were increased at post-procedure days 3 and 7, but the difference among the groups was not statistically significant (P = 0.661, 0.216, respectively). With regard to baseline corneal thickness, only the levofloxacin group exhibited a significant increase from baseline (P = 0.028), whereas the other treatment groups showed no difference from baseline (P = 0.128 in gatifloxacin, 0.161 in BSS group). The mean corneal endothelial damage was 0.81 +/- 0.31% in the levofloxacin group, 0.56 +/- 0.47% in the gatifloxacin group, and 0.53 +/- 0.52% in the BSS group, with no statistically significant difference noted among the groups (P = 0.582). SEM revealed a well-preserved hexagonal endothelial cell mosaic and normal microvilli on the endothelial cell surface in the gatifloxacin and control groups. However, the levofloxacin group showed slightly disintegrated cellular borders. TEM revealed that each group maintained normal intracellular organization, whereas the levofloxacin group exhibited slightly flat cell configuration with irregular folds on the apical cell surface. Intracameral injection of gatifloxacin and levofloxacin was nontoxic in terms of clinical toxicity score, corneal thickness, and viability. However, there were changes on electron microscopy in the levofloxacin group, which may indicate microstructural damage to corneal endothelial cells.

Biometry Characteristics in Adults and Children With Marfan Syndrome: From the Marfan Eye Consortium of Chicago.

PubMed

Kinori, Michael; Wehrli, Sarah; Kassem, Iris S; Azar, Nathalie F; Maumenee, Irene H; Mets, Marilyn B

2017-05-01

To report on the biometric findings of adults and children with Marfan syndrome (MFS) recruited from 2 annual National Marfan Foundation conferences (2012 and 2015). Cross-sectional study. Subjects diagnosed with MFS by Ghent 2 nosology were included for analysis. Subjects were divided into "adults" (≥16 years of age) and "children" (5-15 years of age). Biometric data included values for refractive error, axial length (AL), corneal curvature, anterior chamber depth, lens thickness, and central corneal thickness. Of the 117 subjects evaluated, 74 (35 adults, 32 children, and 7 children <5 years of age) had a definite diagnosis of MFS and were included in the study. The AL was longer (25.25 ± 0.32 mm vs 24.24 ± 0.33 mm, P = .03) and the lens was thicker (3.94 ± 0.09 mm vs 3.62 ± 0.10 mm, P = .03) in adults. Both groups had flat corneas (average keratometry [K med ] of 41.59 ± 0.35 diopters [D] in adults vs 40.89 ± 0.36 D in children, P = .17). A negative correlation was found between AL and K med (-0.33, P < .001). The corneas of patients with MFS with ectopia lentis (EL) were significantly flatter and with higher degree of corneal astigmatism compared to patients without EL (K med of 40.68 ± 0.31 D vs 41.75 ± 0.28 D, P < .01 and corneal astigmatism of 1.68 ± 0.16 D vs 1.13 ± 0.14 D, P = .01). Children with established MFS have flat corneas at least to the same degree as adults. Corneas of patients with MFS with EL are flatter and have a higher degree of corneal astigmatism. We strongly suggest that corneal parameters should be measured if MFS is suspected, especially in children that may not yet have developed EL. Copyright © 2017 Elsevier Inc. All rights reserved.

Biometry Characteristics in Adults and Children With Marfan Syndrome: From the Marfan Eye Consortium of Chicago

PubMed Central

KINORI, MICHAEL; WEHRLI, SARAH; KASSEM, IRIS S.; AZAR, NATHALIE F.; MAUMENEE, IRENE H.; METS, MARILYN B.

2017-01-01

PURPOSE To report on the biometric findings of adults and children with Marfan syndrome (MFS) recruited from 2 annual National Marfan Foundation conferences (2012 and 2015). DESIGN Cross-sectional study. METHODS Subjects diagnosed with MFS by Ghent 2 nosology were included for analysis. Subjects were divided into “adults” (≥16 years of age) and “children” (5–15 years of age). Biometric data included values for refractive error, axial length (AL), corneal curvature, anterior chamber depth, lens thickness, and central corneal thickness. RESULTS Of the 117 subjects evaluated, 74 (35 adults, 32 children, and 7 children <5 years of age) had a definite diagnosis of MFS and were included in the study. The AL was longer (25.25 ± 0.32 mm vs 24.24 ± 0.33 mm, P [ .03) and the lens was thicker (3.94 ± 0.09 mm vs 3.62 ± 0.10 mm, P [ .03) in adults. Both groups had flat corneas (average keratometry [Kmed] of 41.59 ± 0.35 diopters [D] in adults vs 40.89 ± 0.36 D in children, P [ .17). A negative correlation was found between AL and Kmed (L0.33, P < .001). The corneas of patients with MFS with ectopia lentis (EL) were significantly flatter and with higher degree of corneal astigmatism compared to patients without EL (Kmed of 40.68 ± 0.31 D vs 41.75 ± 0.28 D, P < .01 and corneal astigmatism of 1.68 ± 0.16 D vs 1.13 ± 0.14 D, P =.01). CONCLUSIONS Children with established MFS have flat corneas at least to the same degree as adults. Corneas of patients with MFS with EL are flatter and have a higher degree of corneal astigmatism. We strongly suggest that corneal parameters should be measured if MFS is suspected, especially in children that may not yet have developed EL. PMID:28257833

Influence of the corneal optical zone on the point-spread function of the human eye

NASA Astrophysics Data System (ADS)

Rol, Pascal O.; Parel, Jean-Marie A.

1992-08-01

In refractive surgery, a number of surgical techniques have been developed to correct ametropia (refractive defaults) of the eye by changing the exterior shape of the cornea. Because the air-cornea interface makes up for about two thirds of the refractive power of the eye, a refractive correction can be obtained by a suitable reshaping of the cornea. Postoperatively, it is usually observed that the corneal region consists of two or more zones which are characterized by different optical parameters exhibiting in particular different focal distances. Under normal circumstances, only the central area of the cornea is involved in the formation of the retinal image. However, if part of the light entering the eye through peripheral portions of the cornea with refractive properties different from the central area can pass the pupil, an out-of-focus `ghost' image may be overlaid on the retina causing a blur. In such a case the resolution, and the contrast performance of the eye which is expected from a successful operation, may be reduced. This study is an attempt to quantify the vision blur as a function of the diameter of the central zone, i.e., the optical zone which is of importance for vision.

Cross-ancestry genome-wide association analysis of corneal thickness strengthens link between complex and Mendelian eye diseases.

PubMed

Iglesias, Adriana I; Mishra, Aniket; Vitart, Veronique; Bykhovskaya, Yelena; Höhn, René; Springelkamp, Henriët; Cuellar-Partida, Gabriel; Gharahkhani, Puya; Bailey, Jessica N Cooke; Willoughby, Colin E; Li, Xiaohui; Yazar, Seyhan; Nag, Abhishek; Khawaja, Anthony P; Polašek, Ozren; Siscovick, David; Mitchell, Paul; Tham, Yih Chung; Haines, Jonathan L; Kearns, Lisa S; Hayward, Caroline; Shi, Yuan; van Leeuwen, Elisabeth M; Taylor, Kent D; Bonnemaijer, Pieter; Rotter, Jerome I; Martin, Nicholas G; Zeller, Tanja; Mills, Richard A; Staffieri, Sandra E; Jonas, Jost B; Schmidtmann, Irene; Boutin, Thibaud; Kang, Jae H; Lucas, Sionne E M; Wong, Tien Yin; Beutel, Manfred E; Wilson, James F; Uitterlinden, André G; Vithana, Eranga N; Foster, Paul J; Hysi, Pirro G; Hewitt, Alex W; Khor, Chiea Chuen; Pasquale, Louis R; Montgomery, Grant W; Klaver, Caroline C W; Aung, Tin; Pfeiffer, Norbert; Mackey, David A; Hammond, Christopher J; Cheng, Ching-Yu; Craig, Jamie E; Rabinowitz, Yaron S; Wiggs, Janey L; Burdon, Kathryn P; van Duijn, Cornelia M; MacGregor, Stuart

2018-05-14

Central corneal thickness (CCT) is a highly heritable trait associated with complex eye diseases such as keratoconus and glaucoma. We perform a genome-wide association meta-analysis of CCT and identify 19 novel regions. In addition to adding support for known connective tissue-related pathways, pathway analyses uncover previously unreported gene sets. Remarkably, >20% of the CCT-loci are near or within Mendelian disorder genes. These included FBN1, ADAMTS2 and TGFB2 which associate with connective tissue disorders (Marfan, Ehlers-Danlos and Loeys-Dietz syndromes), and the LUM-DCN-KERA gene complex involved in myopia, corneal dystrophies and cornea plana. Using index CCT-increasing variants, we find a significant inverse correlation in effect sizes between CCT and keratoconus (r = -0.62, P = 5.30 × 10 -5 ) but not between CCT and primary open-angle glaucoma (r = -0.17, P = 0.2). Our findings provide evidence for shared genetic influences between CCT and keratoconus, and implicate candidate genes acting in collagen and extracellular matrix regulation.

Comparison of femtosecond laser-assisted descemetic and predescemetic lamellar keratoplasty for keratoconus.

PubMed

Lu, Yan; Grisolia, Ana Beatriz Diniz; Ge, Yi-Rui; Xue, Chun-Yan; Cao, Qian; Yang, Li-Ping; Huang, Zhen-Ping

2017-01-01

The purpose of this study is to compare the outcomes following femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK) with 75% of stromal dissection (predescemetic group) and femtosecond laser-assisted DALK using big-bubble technique with total stromal resection (descemetic group) for the treatment of keratoconus. Twenty eyes of 17 patients with keratoconus were studied. There were 10 eyes of 9 patients in predescemetic group and 10 eyes of 8 patients in descemetic group. The postoperative best-corrected visual acuity (BCVA), manifest refraction, keratometry, endothelial cell density (ECD), and central corneal thickness (CCT) were analyzed. All surgeries were performed uneventfully. At 1 year after surgery, the BCVA, corneal astigmatism, keratometry, CCT, and ECD between two groups were not statistically significant (all P > 0.05). However, the mean manifest refraction was -9.43 ± 7.44 diopter (D) and -1.03 ± 1.13D in predescemetic and descemetic groups, respectively, which was statistically significant between two groups (P < 0.05). The results of BCVA and corneal astigmatism, keratometry, ECD, and CCT were comparable between two groups. However, the mean postoperative manifest refraction was lower in descemetic group.

Translational Immuno- and Neuro-imaging Demonstrate Corneal Neuro-immune Crosstalk

PubMed Central

Hamrah, Pedram; Seyed-Razavi, Yashar; Yamaguchi, Takefumi

2017-01-01

Corneal immuno- and neuro-imaging approaches facilitate in vivo analyses of the cornea, including high-resolution imaging of corneal immune cells and nerves. This approach facilitates the analyses of underlying immune and nerve alterations not detected by clinical slit-lamp examination alone. In this review, we describe recent work performed in our translational ocular immunology center with a focus on ‘bench-to-bedside’ and ‘bedside-to-bench’ research. The ability to visualize dendritiform immune cells (DCs) in patients with laser in vivo confocal microscopy (IVCM), recently discovered in the central murine cornea, has allowed us to demonstrated their utility as a potential surrogate biomarker for inflammatory ocular surface diseases. This biomarker for inflammation allows the measurement of therapeutic efficacy of anti-inflammatory drugs and its utility as an endpoint in clinical trials with high inter-observer agreement. IVCM image analyses from our studies demonstrated a significant increase in DC density and size in ocular disease, a positive correlation between DC density and clinical signs and symptoms of disease and pro-inflammatory tear cytokines, and a strong negative correlation between DC density and subbasal nerve density. In conjunction with pre-clinical research investigating the inflammatory state in a partial or fully denervated cornea, our results indicated that corneal nerves are directly involved in the regulation of homeostasis and immune privilege in the cornea. PMID:27631352

Analysis of incidence of keratoconus in relatives of patients who underwent corneal transplant due to advanced keratoconus using the Orbscan II topographic graphs

NASA Astrophysics Data System (ADS)

López Olazagasti, Estela; Hernández y del Callejo, César E.; Ibarra-Galitzia, Jorge; Ramírez-Zavaleta, Gustavo; Tepichín, Eduardo

2011-10-01

Keratoconus is a corneal disease in which the cornea assumes a conical shape due to an irregular alteration of the internal structure of the corneal tissue and sometimes is progressive, especially in young people. Anatomically, the main signs of keratoconus are thinning of the cornea in its central or paracentral region, usually accompanied by an increase in this part of a high irregular astigmatism, with a consequent loss of vision. Its diagnosis requires a thorough study including the family history, a complete ophthalmologic examination and imaging studies. This diagnosis allows classifying the type of keratoconus, which allow determining options of management, with what it is possible to establish a visual prognosis of each eye. One of the indicators that help in the diagnosis of keratoconus is an inherited familiar propensity. The literature reports an incidence of keratoconus of 11%1 in first-degree relatives of patients with keratoconus. Results suggest an ethnic dependence, which implies that the knowledge of the tendency of keratoconus in the Mexican population is important. In this work, we present the preliminary results of the study realized to a group of relatives of patients who underwent corneal transplant by advanced keratoconus using Orbscan II topographic diagnosis, to determine the predisposition to Keratoconus in this group.e

Correction of hyperopia by intrastromal cutting and biocompatible filler injection (Conference Presentation)

NASA Astrophysics Data System (ADS)

Freidank, Sebastian; Vogel, Alfred; Anderson, Richard R.; Birngruber, Reginald; Linz, Norbert

2017-02-01

For ametropic eyes, LASIK is a common surgical procedure to correct the refractive error. However, the correction of hyperopia is more difficult than that of myopia because the increase of the central corneal curvature by excimer ablation is only possible by intrastromal tissue removal within a ring-like zone in the corneal periphery. For high hyperopia, the ring-shaped indentation leads to problems with the stability and reproducibility of the correction due to epithelial regrowth. Recently, it was shown that the correction of hyperopia can be achieved by implanting intracorneal inlays into a laser-dissected intrastromal pocket. In this paper we demonstrate the feasibility of a new approach in which a transparent, and biocompatible liquid filler material is injected into a laser-dissected corneal pocket, and the refractive change is monitored via OCT. This technique allows for a precise and adjustable change of the corneal curvature. Precise cutting of the intrastromal pocket was achieved by focusing UV laser picosecond pulses from a microchip laser system into the cornea. After laser dissection, the transparent filler material was injected into the pocket. The increase of the refractive power by filler injection was evaluated by taking OCT images from the cornea. With this novel technique, it is possible to precisely correct hyperopia of up to 10 diopters. An astigmatism correction is also possible by using ellipsoidal intrastromal pockets.

Long-term follow-up after submandibular gland transplantation in severe dry eyes secondary to cicatrizing conjunctivitis.

PubMed

Borrelli, Maria; Schröder, Christina; Dart, John K G; Collin, John Richard O; Sieg, Peter; Cree, Ian A; Matheson, Melville A; Tiffany, John M; Proctor, Gordon; van Best, Jaap; Hyde, Nick; Geerling, Gerd

2010-12-01

To evaluate the long-term results of autologous submandibular gland transplantation in eyes with cicatrizing conjunctivitis and to determine biomechanical and biochemical features of the resulting salivary tear film. Prospective, observational case series. Fifteen eyes with cicatrizing conjunctivitis with a viable autologous submandibular gland transplantation were compared with 10 eyes with cicatrizing conjunctivitis and a failed submandibular gland transplantation or no submandibular gland transplantation. Best-corrected visual acuity, frequency of tear substitute instillation, severity of dry eye discomfort, lid margin erythema, conjunctival hyperemia, corneal epithelial edema, tear film break-up time, Schirmer test results, and corneal fluorescein and conjunctival Rose Bengal staining were evaluated. In a subgroup central corneal thickness and sensitivity, corneal epithelial barrier function, conjunctival and lid margin flora, and conjunctival impression cytologic analysis results were evaluated. In 3 patients, preoperative and postoperative tear samples were analyzed for viscosity, surface tension, and presence of mucins. Submandibular gland autotransplantation resulted in long-term improvement of subjective, objective, and some ocular surface parameters. Salivary mucins were detectable in salivary tears after submandibular gland transplantation. The viscosity of salivary tears was more similar to normal saliva and the surface tension was intermediate between the 2 original secretions. Submandibular gland autotransplantation provides long-term relief from pain and reduces the need for frequent installation of lubricants. Copyright © 2010 Elsevier Inc. All rights reserved.

Reasons For Not Performing Keratorefractive Surgery in Patients Seeking Refractive Surgery in a Hospital-Based Cohort in “Yemen”

PubMed Central

Bamashmus, Mahfouth A.; Saleh, Mahmoud F.; Awadalla, Mohamed A.

2010-01-01

Background: To determine and analyze the reasons why keratorefractive surgery, laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) were not performed in patients who presented for refractive surgery consultation. Materials and Methods: A retrospective observational study was performed between January 2006 and December 2007 in the Yemen Magrabi Hospital. The case records of 2,091 consecutive new patients who presented for refractive surgery were reviewed. Information from the pre-operative ophthalmic examination, such as refractive error, corneal topography and visual acuity, were analyzed. The reasons for not performing LASIK and PRK in the cases that were rejected were recorded and analyzed. Results: In this cohort, 1,660 (79.4%) patients were advised to have LASIK or PRK from the 2,091 patients examined. LASIK and PRK were not advised in 431 (21%) patients. The most common reasons for not performing the surgery were high myopia >-11.00 Diopters (19%), keratoconus (18%), suboptimal central corneal thickness (15%), cataract (12%) and keratoconus suspect (forme fruste keratoconus) (10%). Conclusion: Patients who requested keratorefractive surgery have a variety of problems and warrant comprehensive attention to selection criteria on the part of the surgeon. Corneal topographies and pachymetry of refractive surgery candidates need to be read cautiously. High-refractive error, keratoconus and insufficient corneal thickness were found to be the leading reasons for not performing keratorefractive surgery in this study. PMID:21180437

[Slit lamp optical coherence tomography study of anterior segment changes after phacoemulsification and foldable intraocular lens implantation].

PubMed

Yan, Pi-song; Zhang, Zhen-ping; Lin, Hao-tian; Wu, Wen-jie; Bai, Ling

2009-09-01

To investigate quantitative changes of the anterior segment configuration after clear corneal incision phacoemulsification and foldable intraocular lens (IOL) implantation with slit-lamp-adapted optical coherence tomography (SL-OCT). In prospective consecutive case series, clear corneal incision phacoemulsification and foldable intraocular lens implantation were performed in 44 eyes of 40 patients. The changes of the anterior segment configuration were performed by SL-OCT before and 1 day, 1 week, 2 weeks and 1 month after surgery. SPSS 16.0 software was used to analyze statistical difference. For all patients, the central corneal thickness (CCT) and the incisional corneal thickness (ICT) increased significantly 1 day after surgery (CCT increased 99.59 microm, ICT increased 234.57 microm; P = 0.490). At 1 month, the CCT almost had returned to baseline, but the ICT had been thicker about 19.25 microm than baseline(P = 0.001). The measurements of ACD, AOD500, AOD750, TISA500, TISA750 also increased significantly 1 day after surgery. Although the ACD had no changes within 2 weeks (all P < 0.05), it had been not stable. The changes of the width of the anterior chamber had been stable in the early period after surgery (all P > 0.05). The SL-OCT could impersonality and quantificationally evaluate the anterior segment changes induced by cataract surgery.

Distribution and associations of intraocular pressure in 7- and 12-year-old Chinese children: The Anyang Childhood Eye Study.

PubMed

Li, Shuning; Li, Shi-Ming; Wang, Xiao-Lei; Kang, Meng-Tian; Liu, Luo-Ru; Li, He; Wei, Shi-Fei; Ran, An-Ran; Zhan, Siyan; Thomas, Ravi; Wang, Ningli

2017-01-01

To report the intraocular pressure (IOP) and its association with myopia and other factors in 7 and 12-year-old Chinese children. All children participating in the Anyang Childhood Eye Study underwent non-contact tonometry as well as measurement of central corneal thickness (CCT), axial length, cycloplegic auto-refraction, blood pressure, height and weight. A questionnaire was used to collect other relevant information. Univariable and multivariable analysis were performed to determine the associations of IOP. A total of 2760 7-year-old children (95.4%) and 2198 12-year-old children (97.0%) were included. The mean IOP was 13.5±3.1 mmHg in the younger cohort and 15.8±3.5 mmHg in older children (P<0.0001). On multivariable analysis, higher IOP in the younger cohort was associated with female gender (standardized regression coefficient [SRC], 0.11, P<0.0001), increasing central corneal thickness (SRC, 0.39, P<0.0001), myopia (SRC, 0.05, P = 0.03), deep anterior chamber (SRC, 0.07, P<0.01), smaller waist (SRC, 0.07, P<0.01) and increasing mean arterial pressure (SRC, 0.13, P<0.0001). In the older cohort, higher IOP was again associated with female gender (SRC, 0.16, P<0.0001), increasing central corneal thickness (SRC, 0.43, P<0.0001), deep anterior chamber (SRC, 0.09, P<0.01), higher body mass index (SRC, 0.07, P = 0.04) and with increasing mean arterial pressure (SRC, 0.09, P = 0.01), age at which reading commenced (SRC, 0.10, P<0.01) and birth method (SRC, 0.09, P = 0.01), but not with myopia (SRC, 0.09, P = 0.20). In Chinese children, higher IOP was associated with female gender, older age, thicker central cornea, deeper anterior chamber and higher mean arterial pressure. Higher body mass index, younger age at commencement of reading and being born of a caesarean section was also associated with higher IOP in adolescence.

Living with Lowe's Syndrome. A Guide for Families, Friends, and Professionals.

ERIC Educational Resources Information Center

Lowe's Syndrome Association, Inc., West Lafayette, IN.

The document describes Lowe's syndrome, a hereditary condition that affects only males and is typically diagnosed during the first year of life. Effects of Lowe's syndrome on the eyes (cataracts, glaucoma, corneal degeneration, and strabismus) are discussed, as well as related problems with the central nervous system, muscles, kidneys, bones, and…

Agreement between central corneal thickness measured using Pentacam, ultrasound pachymetry, specular microscopy and optic biometer Lenstar LS 900 and the influence of intraocular pressure.

PubMed

Borrego-Sanz, L; Sáenz-Francés, F; Bermudez-Vallecilla, M; Morales-Fernández, L; Martínez-de-la-Casa, J M; Santos-Bueso, E; Jañez, L; García-Feijoo, J

2014-01-01

To compare central corneal thickness (CCT) values obtained by Lenstar (LE), Pentacam (PC), specular microscopy (SM) and ultrasound pachymetry (UP) in healthy corneas and study their influence on intraocular pressure (IOP) readings determined by Goldmann applanation tonometry (GAT). CCT was measured in 76 healthy subjects by LE, PC, SM and UP. We established Lin's concordance correlation coefficient (ρ-C) between different techniques. The influence of CCT on GAT was established through univariate linear regression models, IOP being the dependent variable. The highest ρ-C was found between LE and SM at 0.94 (95% CI: 0.91-0.96) and between LE and UP at 0.95 (95% CI: 0.94-0.97). IOP readings showed less variability when CCT was determined using LE (7.7%, B = 0.16; 95% CI: 0.004-0.28). Although CCT values obtained with UP, PC, SM and LE show good correlation, these methods are not completely interchangeable. The amount of IOP variation differs when CCT is determined using LE or SM. © 2014 S. Karger AG, Basel.

Changes in shape and astigmatism of total, anterior, and posterior cornea after long versus short clear corneal incision cataract surgery.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Hirata, Akira; Yoshimura, Koichi

2018-01-01

To compare changes in the shape and astigmatism of the total, anterior, and posterior cornea between eyes with long-length clear corneal incisions (CCIs) and eyes with short-length CCIs in cataract surgery. Hayashi Eye Hospital, Fukuoka, Japan. Prospective case series. Both eyes of patients having phacoemulsification with temporal CCIs were randomized to have a long-length (≥1.75 mm) or short-length (<1.75 mm) CCI. Corneal astigmatic changes were decomposed to vertical/horizontal (Jackson cross-cylinder, axes at 180 degrees and 90 degrees [J0]) and oblique changes (Jackson cross-cylinder, axes at 45 degrees and 135 degrees [J45]) using power vector analysis. Corneal shape changes were assessed using the average of the difference map on videokeratography 2 days and 2, 4, and 8 weeks postoperatively. The mean J0 and J45 values of the total cornea in the 120 eyes evaluated were significantly greater in the long CCI group than in the short CCI group at all follow-ups (P ≤ .0290). The videokeratography showed a wedge-shaped flattening in the total and anterior cornea and a steepening in the posterior cornea around the CCI 2 days postoperatively in both groups. This wound-related flattening of the total and anterior cornea rapidly reduced but persisted until 8 weeks, whereas the steepening of the posterior cornea disappeared within 4 weeks. These changes extended closer to the central cornea in the long CCI group than in the short CCI group. Corneal astigmatic changes were significantly greater after long CCI than after short CCI. The wound-related shape changes occurred immediately postoperatively but rapidly diminished. Copyright © 2018 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Comparison of the characteristics in hen and quail corneas as experimental models of refractive surgery.

PubMed

Gonçalves, G C; Pérez-Merino, P; Martínez-García, M C; Barcía, A; Merayo-Loves, J

2016-07-01

To compare the histological, morphological and the biophysical measurements between hen and quail corneas, in order to determine which of them were better suited for use as an animal model for research into corneal refractive surgery. A study was performed using the biophysical measurements of the cornea (curvature, thickness, refraction, and axial length) of 20 animals (10 hens and 10 quails). The corneas were then prepared for histological analysis under microscopy light. The analysis showed that both groups have the same number of corneal layers as the human cornea and with an evident Bowman's layer. The thickness of the hen cornea and axial length of the eye, 225.3±18.4μm and 12.8±0.25mm, respectively, were larger than that of the quail (P<.01 and P<.001, respectively). The radius of curvature for the hen central cornea, 3.65±0.08mm, was greater than that for the quail (P<.001), but the refractive power of each cornea was similar. The proportion of total corneal thickness of the hen stroma, 82.6%, was more similar to that of the human than was the quail stroma, 72.5%. Within the hen stroma, the density of keratocytes, 8.57±1.49 per 5,000μm(2), was about half that in the quail stroma (P<.005). Because of the large size of the hen cornea, the stromal thickness and proportional similarity of the corneal layers with human cornea, the hen maybe better than the quail as an alternative species suitable for use in studies of corneal refractive surgery. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Morphologic features and surgically induced astigmatism of femtosecond laser versus manual clear corneal incisions.

PubMed

Zhu, Sha; Qu, Naibin; Wang, Wei; Zhu, Yanan; Shentu, Xingchao; Chen, Peiqing; Xu, Wen; Yao, Ke

2017-11-01

To compare the morphologic features and surgically induced astigmatism (SIA) between laser and manual clear corneal incisions (CCIs) after femtosecond laser-assisted cataract surgery. Eye Center, 2nd Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, China. Prospective case series. Patients had femtosecond laser-assisted cataract surgery with a CCI created with the laser or manually after random allocation. The corrected distance visual acuity, corneal topography, and anterior segment optical coherence tomography were assessed at the 1-day, 1-week, 1-month, and 3-month follow-ups. The laser CCI group comprised 45 eyes and the manual CCI group, 48 eyes. The SIA was significantly lower in the manual CCI group than the laser CCI group at all visits (P < .05). At the 1-day and 1-week follow-ups, the mean CCI thickness was significantly smaller in the manual CCI group (P < .05). In the laser CCI group, the perpendicular linear distance between the external wound opening and the corneal vertex central line was statistically shorter than in the manual CCI group (P < .05). At 3 months, the SIA was correlated with the perpendicular linear distance with a Pearson correlation coefficient of -0.341 (P = .001). Femtosecond laser-created CCIs for cataract surgery caused more SIA than manually created CCIs, which could have resulted from inaccurate or uncertain corneal incision positioning of the femtosecond machine. Manual creation of CCIs is recommended in femtosecond laser-assisted cataract surgery until the locating system for the femtosecond laser incision is updated. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Femtosecond laser correction of presbyopia (INTRACOR) in emmetropes using a modified pattern.

PubMed

Thomas, Bettina C; Fitting, Anna; Auffarth, Gerd U; Holzer, Mike P

2012-12-01

To evaluate functional results and corneal changes after femtosecond laser correction of presbyopia (INTRACOR, Technolas Perfect Vision GmbH) in emmetropes using a modified treatment pattern over a 12-month period. Twenty eyes from 20 emmetropic patients were treated with a modified intrastromal INTRACOR pattern consisting of 5 central rings and 8 radial cuts in a prospective, nonrandomized, uncontrolled, open, single-center, clinical study. Refraction, visual acuity, endothelial cell density, corneal pachymetry, total corneal power, and stray light were evaluated preoperatively and 1 (except endothelial cell density and stray light), 3, 6, and 12 months postoperatively. Patients filled out a subjective questionnaire at 12 months postoperatively. Comparison of preoperative versus 12-month postoperative median values revealed a significant improvement in uncorrected near visual acuity (UNVA) from 0.60 (20/80) to 0.10 logMAR (20/25) (P<.0001) and a significant decrease in corrected distance visual acuity (CDVA) from -0.10 (20/16) to 0.00 logMAR (20/20), which equals a median loss of one line (P=.0005). Fifteen percent of patients lost two lines of CDVA in the treated eye. Subjective spherical equivalent refraction remained unchanged at 0.00 diopters (D) (P=.194). After INTRACOR treatment, significant corneal steepening of 1.40 D and midperipheral flattening of 0.50 D occurred (both P<.0001). Corneal pachymetry at the thinnest point and endothelial cell density did not change significantly (P=.829 and P=.058, respectively). After 12 months, the modified INTRACOR pattern improved UNVA in emmetropic patients without inducing a myopic shift or significant changes in endothelial cell density or pachymetry. Copyright 2012, SLACK Incorporated.

Analyses of Factors Affecting Endothelial Cell Density in an Eye Bank Corneal Donor Database.

PubMed

Kwon, Ji Won; Cho, Kyong Jin; Kim, Hong Kyu; Lee, Jimmy K; Gore, Patrick K; McCartney, Mitchell D; Chuck, Roy S

2016-09-01

To analyze the factors affecting central corneal endothelial cell density (ECD) in an eye bank corneal donor database. The Lion's Eye Institute corneal donor database consisting of 18,665 donors (34,234 corneas) aged 20 years or older was analyzed. In particular, differences in the ECD based on age, sex, race, prior ocular surgery, a history of systemic diseases, and smoking were investigated. Furthermore, risk factors for donor cell count inadequacy (defined here as ECD less than 2000/mm) were identified. ECD decreased with age. Regarding race, the average ECD of African American donors was higher than those of white or Hispanic donors. A history of diabetes mellitus (DM) and ocular surgery were associated with a lower ECD. Donor medical history of hypertension, glaucoma, depression, dementia, Parkinson disease, hyper- or hypothyroidism, or smoking did not seem to affect the ECD. The risk factors for donor cell count inadequacy, based on binary logistic regression analyses were advanced age [65-74 years yielded an odds ratio of 17.8; confidence interval (CI), 10.6-29.8; P < 0.001; and 75-99 years yielded an odds ratio of 24.6 (CI, 14.5-41.61; P < 0.001) when compared with 20-34 years], cataract surgery (odds ratio, 4.3; CI, 4.0-4.8; P < 0.001), and DM (odds ratio, 1.2; CI, 1.1-1.3; P = 0.001). Age, race, ocular surgery (cataract and refractive), and DM seem to significantly affect donor corneal ECD. Of these variables, age, a history of cataract surgery, and DM were found to be the greatest risk factors for inadequate donor cell density (less than 2000/mm).

Slit-lamp photography and videography with high magnifications

PubMed Central

Yuan, Jin; Jiang, Hong; Mao, Xinjie; Ke, Bilian; Yan, Wentao; Liu, Che; Cintrón-Colón, Hector R; Perez, Victor L; Wang, Jianhua

2015-01-01

Purpose To demonstrate the use of the slit-lamp photography and videography with extremely high magnifications for visualizing structures of the anterior segment of the eye. Methods A Canon 60D digital camera with Movie Crop Function was adapted into a Nikon FS-2 slit-lamp to capture still images and video clips of the structures of the anterior segment of the eye. Images obtained using the slit-lamp were tested for spatial resolution. The cornea of human eyes was imaged with the slit-lamp and the structures were compared with the pictures captured using the ultra-high resolution optical coherence tomography (UHR-OCT). The central thickness of the corneal epithelium and total cornea was obtained using the slit-lamp and the results were compared with the thickness obtained using UHR-OCT. Results High-quality ocular images and higher spatial resolutions were obtained by using the slit-lamp with extremely high magnifications and Movie Crop Function, rather than the traditional slit-lamp. The structures and characteristics of the cornea, such as the normal epithelium, abnormal epithelium of corneal intraepithelial neoplasia, LASIK interface, and contact lenses, were clearly visualized using this device. These features were confirmed by comparing the obtained images with those acquired using UHR-OCT. Moreover, the tear film debris on the ocular surface and the corneal nerve in the anterior corneal stroma were also visualized. The thicknesses of the corneal epithelium and total cornea were similar to that measured using UHR-OCT (P < 0.05). Conclusions We demonstrated that the slit-lamp photography and videography with extremely high magnifications allows better visualization of the anterior segment structures of the eye, especially of the epithelium, when compared with the traditional slit-lamp. PMID:26020484

Corneal Endothelial Alterations in Chronic Renal Failure.

PubMed

Sati, Alok; Jha, Ashok; Moulick, P S; Shankar, Sandeep; Gupta, Sandeep; Khan, M A; Dogra, Manu; Sangwan, Virender S

2016-10-01

To evaluate the corneal endothelial changes in patients with chronic renal failure. A total of 128 corneas of 128 subjects were studied, and 3 groups were formed. The first, the dialyzed group, composed of 32 corneas of 32 patients; the second, the nondialyzed group, composed of 34 corneas of 34 patients; and the third, the age-matched control group, composed of 64 corneas of 64 healthy subjects were examined by a specular microscope and the endothelial parameters were compared. The dialyzed group (enhanced level of toxins in the blood) was further analyzed to assess the influence of blood urea, serum creatinine, serum calcium, and serum phosphorus including the duration of dialysis on corneal endothelium. On comparing the 3 groups using analysis of variance and posthoc tests, a significant difference was found in the central corneal thickness (CCT) and endothelial cell density (CD) between the control (CCT: 506 ± 29 μm, CD: 2760 ± 304 cells/mm) and dialyzed groups (CCT: 549 ± 30 μm, CD: 2337 ± 324 cells/mm) [P < 0.001 (CCT); P < 0.001 (CD)]; control and nondialyzed groups (CCT: 524 ± 27 μm, CD: 2574 ± 260 cells/mm) [P = 0.023 (CCT); P = 0.016 (CD)]; and dialyzed and nondialyzed groups [P = 0.002 (CCT); P = 0.007 (CD)]. Using the linear generalized model, a significant correlation was found between the endothelial parameters and blood urea only [P = 0.006 (CCT), 0.002 (coefficient of variation), 0.022 (CD), and 0.026 (percentage of hexagonality)], although the correlation was poorly positive for CCT but poorly negative for the remaining endothelial parameters. Corneal endothelial alteration is present in patients with chronic renal failure, more marked in patients undergoing hemodialysis and with raised blood urea level.

Resolvin E1 analog RX-10045 0.1% reduces corneal stromal haze in rabbits when applied topically after PRK.

PubMed

Torricelli, Andre A M; Santhanam, Abirami; Agrawal, Vandana; Wilson, Steven E

2014-01-01

To perform a masked study to determine whether resolvin E1 (RvE1), a lipid-derived immunomodulator, could regulate the development of corneal haze and opacity-related myofibroblasts after opacity-generating high correction photorefractive keratectomy (PRK) in rabbits. Three groups of eight rabbits each were included in the study. Nine diopter (D) PRK for myopia was performed in each test cornea, and the eyes were treated with 30 µl of topical solution every 4 h (six times a day) for 5 days starting immediately after PRK. Group 1 was treated with 0.1% RX-10045, a prodrug of an RvE1 analog; group 2 was treated with 0.01% RX-10045; and group 3 was treated with vehicle control solution. At 1 month after PRK, haze was graded at the slit-lamp by a masked observer. Immunohistochemistry for α-smooth muscle actin (SMA) was performed on the central cornea of each test eye to determine the anterior stromal myofibroblast density. Corneal opacity was significantly lower in the 0.1% RX-10045 group, but not the 0.01% RX-10045 group, compared to the vehicle control group (p=0.029), at 1 month after -9.0D PRK. At 1 month after -9.0D PRK, SMA+ myofibroblast densities in the anterior stroma were not statistically significantly different among the three groups, although a trend toward lower myofibroblast generation was noted in the 0.1% RX-10045 group. Topical 0.1% RX-10045, a prodrug of an RvE1 analog, reduces corneal opacity after haze-generating PRK in rabbits. Further studies are needed to determine the precise points at which RvE1 decreases corneal opacity after injury.

Analysis of the learning curve for pre-cut corneal specimens in preparation for lamellar transplantation: a prospective, single-centre, consecutive case series prepared at the Lions New South Wales Eye Bank.

PubMed

Martin, Aifric Isabel; Devasahayam, Rajnesh; Hodge, Christopher; Cooper, Simon; Sutton, Gerard L

2017-09-01

This study is the first paper to establish a learning curve by a single technician. Preparation of pre-cut corneal endothelial grafts commenced at Lions New South Wales Eye Bank in December 2014. The primary objective of this study was to review the safety and reliability of the preparation method during the first year of production. This is a hospital-based, prospective case series. There were 234 consecutive donor corneal lenticules. Donor lenticules were prepared by a single operator using a linear cutting microkeratome. Immediately prior to cutting, central corneal thickness values were recorded. Measurements of the corneal bed were taken immediately following lenticule preparation. Outcomes were separated by blade sizes, and intended thickness was compared to actual thickness for each setting. Early specimens were compared to later ones to assess for a learning curve within the technique. The main parameter measured is the mean difference from intended lamellar cut thickness. The mean final cut thickness was 122.36 ± 20.35 μm, and the mean difference from intended cut was 30.17 ± 37.45 μm. No significant difference was found between results achieved with early specimens versus those achieved with later specimens (P = 0.425). Thin, reproducible endothelial grafts can routinely be produced by trained technicians at their respective eye banks without significant concerns for an extended learning curve. This service can reduce perioperative surgical complexity, required surgical paraphernalia and theatre times. The consistent preparation of single-pass, ultrathin pre-cut corneas may have additional advantages for surgeons seeking to introduce lamellar techniques. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

SMILE and Wavefront-Guided LASIK Out-Compete Other Refractive Surgeries in Ameliorating the Induction of High-Order Aberrations in Anterior Corneal Surface

PubMed Central

2016-01-01

Purpose. To compare the change of anterior corneal higher-order aberrations (HOAs) after laser in situ keratomileusis (LASIK), wavefront-guided LASIK with iris registration (WF-LASIK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE). Methods. In a prospective study, 82 eyes underwent LASIK, 119 eyes underwent WF-LASIK, 88 eyes underwent FS-LASIK, and 170 eyes underwent SMILE surgery. HOAs were measured with Pentacam device preoperatively and 6 months after surgery. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs, spherical aberration (SA), horizontal coma, and vertical coma over 6 mm diameter central corneal zone. Results. Six months postoperatively, all procedures result in increase of anterior corneal total HOAs and SA. There were no significant differences in the induced HOAs between LASIK and FS-LASIK, while SMILE induced fewer total HOAs and SA compared with LASIK and FS-LASIK. Similarly, WF-LASIK also induced less total HOAs than LASIK and FS-LASIK, but only fewer SA than FS-LASIK (P < 0.05). No significant difference could be detected in the induced total HOAs and SA between SMILE and WF-LASIK, whereas SMILE induced more horizontal coma and vertical coma compared with WF-LASIK (P < 0.05). Conclusion. FS-LASIK and LASIK induced comparable anterior corneal HOAs. Compared to LASIK and FS-LASIK, both SMILE and WF-LASIK showed advantages in inducing less total HOAs. In addition, SMILE also possesses better ability to reduce the induction of SA in comparison with LASIK and FS-LASIK. However, SMILE induced more horizontal coma and vertical coma compared with WF-LASIK, indicating that the centration of SMILE procedure is probably less precise than WF-LASIK. PMID:27818792

Corneal endothelium in xeroderma pigmentosum: clinical specular microscopy study.

PubMed

Mohamed, Ashik; Peguda, Rajini; Ramappa, Muralidhar; Ali, Mohammad Javed; Chaurasia, Sunita

2016-06-01

Xeroderma pigmentosum is a condition caused due to a defective DNA repair mechanism when exposed to ultraviolet radiation. Many of the patients with this disorder develop severely oedematous cornea with varying degrees of anterior corneal haze, which necessitates a full-thickness keratoplasty or selective endothelial keratoplasty. Presence of corneal oedema suggests that these patients have a dysfunctional endothelium. The purpose of this study is to evaluate the corneal endothelium in the patients with xeroderma pigmentosum when clinical specular microscopy was feasible. Thirteen patients with classic skin changes of xeroderma pigmentosum were included in the study conducted during January 2010-December 2012. An age-matched group of 13 volunteers were included as controls who were emmetropes without any history of ocular or systemic illness. Corneal endothelium was assessed using specular microscopy from the central clear area of cornea. The mean age of the patients with xeroderma pigmentosum was 16.6±7.2 years and that of the controls was 17.4±6.9 years (p=0.78). The number of analysed cells and endothelial cell density were significantly higher in controls (p<0.001), whereas the average cell area, coefficient of variation of cell area and maximum cell area were significantly higher in xeroderma pigmentosum (p≤0.007). The specular microscopic findings in patients with xeroderma pigmentosum are suggestive of an accelerated endothelial cell loss. It is pertinent that the treating physicians must be involved in emphasising proper ocular protection from ultraviolet radiation to prevent avoidable blindness from xeroderma pigmentosum. 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/

Optical side-effects of fs-laser treatment in refractive surgery investigated by means of a model eye

PubMed Central

Ackermann, Roland; Kammel, Robert; Merker, Marina; Kamm, Andreas; Tünnermann, Andreas; Nolte, Stefan

2013-01-01

Optical side-effects of fs-laser treatment in refractive surgery are investigated by means of a model eye. We show that rainbow glare is the predominant perturbation, which can be avoided by randomly distributing laser spots within the lens. For corneal applications such as fs-LASIK, even a regular grid with spot-to-spot distances of ~3 µm is sufficient to minimize rainbow glare perception. Contrast sensitivity is affected, when the lens is treated with large 3D-patterns. PMID:23413236

Variation of axial and oblique astigmatism with accommodation across the visual field

PubMed Central

Liu, Tao; Thibos, Larry N.

2017-01-01

In this study we investigated the impact of accommodation on axial and oblique astigmatism along 12 meridians of the central 30° of visual field and explored the compensation of corneal first-surface astigmatism by the remainder of the eye's optical system. Our experimental evidence revealed no systematic effect of accommodation on either axial or oblique astigmatism for two adult populations (myopic and emmetropic eyes). Although a few subjects exhibited systematic changes in axial astigmatism during accommodation, the dioptric value of these changes was much smaller than the amount of accommodation. For most subjects, axial and oblique astigmatism of the whole eye are both less than for the cornea alone, which indicates a compensatory role for internal optics at all accommodative states in both central and peripheral vision. A new method for determining the eye's optical axis based on visual field maps of oblique astigmatism revealed that, on average, the optical axis is 4.8° temporal and 0.39° superior to the foveal line-of-sight in object space, which agrees with previous results obtained by different methodologies and implies that foveal astigmatism includes a small amount of oblique astigmatism (0.06 D on average). Customized optical models of each eye revealed that oblique astigmatism of the corneal first surface is negligible along the pupillary axis for emmetropic and myopic eyes. Individual variation in the eye's optical axis is due in part to misalignment of the corneal and internal components that is consistent with tilting of the crystalline lens relative to the pupillary axis. PMID:28362902

[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.

Surgical treatment of advanced pellucid marginal degeneration.

PubMed

Rasheed, K; Rabinowitz, Y S

2000-10-01

To determine the efficacy of simultaneous peripheral crescentic lamellar keratoplasty (LK) and central penetrating keratoplasty (PK) for advanced pellucid marginal degeneration (PMD). Retrospective, noncomparative, interventional case series. Five patients with advanced PMD. Simultaneous peripheral crescentic LK and central PK followed by selective suture removal and astigmatic keratotomy in the postoperative period. These included interval of time required for visual rehabilitation, best spectacle-corrected visual acuity achieved, and amount of corneal astigmatism, as measured by videokeratography. Measuring the change in corneal astigmatism by videokeratography over the subsequent follow-up period after spectacle correction had been prescribed assessed stability of the achieved refraction. Visual acuity results were 20/40 in three eyes, 20/80 in one eye, and 20/400 in one eye. The latter two had decreased acuity from posterior subcapsular cataract formation, which may have been caused by topical steroid use. The time required for visual rehabilitation ranged from 5.13 to 10.93 (mean, 9.92) months, and the amount of corneal astigmatism at the end of this period ranged from 0.3 diopters (D) to 5.3 D. A tendency for an increase in "with the rule astigmatism" after the rehabilitation period was noted. Two patients had elevations of intraocular pressure that responded to reduction in topical steroid dose. The short-term results with this technique are excellent in that it provides early and stable visual rehabilitation in patients with advanced PMD. Low to moderate levels of postkeratoplasty astigmatism were achieved in all the eyes treated. The usual tendency of an increase in "against the rule astigmatism" that occurs when PK alone is done for PMD was eliminated.

Subclinical Increased Anterior Stromal Reflectivity With Topical Taprenepag Isopropyl

PubMed Central

Schachar, Ronald A.; Raber, Susan; Thomas, Kristina V.; Benetz, Beth Ann M.; Szczotka-Flynn, Loretta B.; Zhang, Min; Howell, Scott J.; Lass, Jonathan H.

2016-01-01

Purpose To assess the effect of topical taprenepag isopropyl on each layer of the cornea by confocal microscopy. Methods Thirty-two ocular hypertensive or glaucoma patients were randomized into a 2-period, crossover study of 14 days of 0.1% taprenepag alone and in unfixed combination with 0.005% latanoprost (combination therapy). Baseline and sequential slit-lamp biomicroscopy, fluorescein staining, central ultrasonic pachymetry, and confocal microscopy were performed. Confocal images were analyzed for the density of the central superficial and basal epithelium, midstromal keratocytes, and endothelium, as well as endothelial coefficient of variation and percentage of hexagonal cells, and reflectivity of anterior stromal and midstromal layers. Results Corneal staining increased from baseline, reaching a peak at day 13 (69% and 63% of subjects treated with monotherapy and combination therapy, respectively), which resolved by day 35. A statistically significant increase in mean corneal thickness for both eyes and both treatments occurred on days 7 and 13 (range, 20–27 μm; P < 0.001) but recovered (≤6 μm) by day 35. No statistically significant changes were observed in the basal epithelial, midstromal, or endothelial cells. Mean ratio of average reflectivity of anterior stroma to midstroma increased on days 13 and 35 in period 1 for each treatment (range, 1.2–1.9; P < 0.001), and this increase persisted during period 2. Conclusions Anterior stromal reflectivity may remain increased even when biomicroscopic and confocal images of corneal layers remain normal or have recovered after topical taprenepag. This subclinical measure may be useful to detect a persistent adverse effect of a topical agent on the cornea. PMID:22549238

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.

Collagen cross-linking using riboflavin and ultraviolet-a for corneal thinning disorders: an evidence-based analysis.

PubMed

Pron, G; Ieraci, L; Kaulback, K

2011-01-01

The main objectives for this evidence-based analysis were to determine the safety and effectiveness of photochemical corneal collagen cross-linking with riboflavin (vitamin B(2)) and ultraviolet-A radiation, referred to as CXL, for the management of corneal thinning disease conditions. The comparative safety and effectiveness of corneal cross-linking with other minimally invasive treatments such as intrastromal corneal rings was also reviewed. The Medical Advisory Secretariat (MAS) evidence-based analysis was performed to support public financing decisions. SUBJECT OF THE EVIDENCE-BASED ANALYSIS: The primary treatment objective for corneal cross-linking is to increase the strength of the corneal stroma, thereby stabilizing the underlying disease process. At the present time, it is the only procedure that treats the underlying disease condition. The proposed advantages for corneal cross-linking are that the procedure is minimally invasive, safe and effective, and it can potentially delay or defer the need for a corneal transplant. In addition, corneal cross-linking does not adversely affect subsequent surgical approaches, if they are necessary, or interfere with corneal transplants. The evidence for these claims for corneal cross-linking in the management of corneal thinning disorders such as keratoconus will be the focus of this review. The specific research questions for the evidence review were as follows: TECHNICAL: How technically demanding is corneal cross-linking and what are the operative risks? What is known about the broader safety profile of corneal cross-linking?Effectiveness - Corneal Surface Topographic Affects:What are the corneal surface remodeling effects of corneal cross-linking?Do these changes interfere with subsequent interventions, particularly corneal transplant known as penetrating keratoplasty (PKP)?Effectiveness -Visual Acuity:What impacts does the remodeling have on visual acuity?Are these impacts predictable, stable, adjustable and durable?Effectiveness - Refractive Outcomes: What impact does remodeling have on refractive outcomes?Effectiveness - Visual Quality (Symptoms): What impact does corneal cross-linking have on vision quality such as contrast vision, and decreased visual symptoms (halos, fluctuating vision)?Effectiveness - Contact lens tolerance: To what extent does contact lens intolerance improve after corneal cross-linking?Vision-Related QOL: What is the impact of corneal cross-linking on functional visual rehabilitation and quality of life?PATIENT SATISFACTION: Are patients satisfied with their vision following the procedure?Disease Process:What impact does corneal cross-linking have on the underling corneal thinning disease process?Does corneal cross-linking delay or defer the need for a corneal transplant?What is the comparative safety and effectiveness of corneal cross-linking compared with other minimally invasive treatments for corneal ectasia such as intrastromal corneal rings? TARGET POPULATION AND CONDITION Corneal ectasia (thinning) disorders represent a range of disorders involving either primary disease conditions, such as keratoconus (KC) and pellucid marginal corneal degeneration, or secondary iatrogenic conditions, such as corneal thinning occurring after laser in situ keratomileusis (LASIK) refractive surgery. Corneal thinning is a disease that occurs when the normally round dome-shaped cornea progressively thins causing a cone-like bulge or forward protrusion in response to the normal pressure of the eye. The thinning occurs primarily in the stroma layers and is believed to be a breakdown in the collagen process. This bulging can lead to irregular astigmatism or shape of the cornea. Because the anterior part of the cornea is responsible for most of the focusing of the light on the retina, this can then result in loss of visual acuity. The reduced visual acuity can make even simple daily tasks, such as driving, watching television or reading, difficult to perform. Keratoconus is the most common form of corneal thinning disorder and involves a noninflammatory chronic disease process of progressive corneal thinning. Although the specific cause for the biomechanical alterations in the corneal stroma is unknown, there is a growing body of evidence suggesting that genetic factors may play an important role. Keratoconus is a rare disease (< 0.05% of the population) and is unique among chronic eye diseases because it has an early onset, with a median age of 25 years. Disease management for this condition follows a step-wise approach depending on disease severity. Contact lenses are the primary treatment of choice when there is irregular astigmatism associated with the disease. Patients are referred for corneal transplants as a last option when they can no longer tolerate contact lenses or when lenses no longer provide adequate vision. Keratoconus is one of the leading indications for corneal transplants and has been so for the last 3 decades. Despite the high success rate of corneal transplants (up to 20 years) there are reasons to defer it as long as possible. Patients with keratoconus are generally young and a longer-term graft survival of at least 30 or 40 years may be necessary. The surgery itself involves lengthy time off work and postsurgery, while potential complications include long-term steroid use, secondary cataracts, and glaucoma. After a corneal transplant, keratoconus may recur resulting in a need for subsequent interventions. Residual refractive errors and astigmatism can remain challenges after transplantation, and high refractive surgery and regraft rates in KC patients have been reported. Visual rehabilitation or recovery of visual acuity after transplant may be slow and/or unsatisfactory to patients. Corneal cross-linking involves the use of riboflavin (vitamin B(2)) and ultraviolet-A (UVA) radiation. A UVA irradiation device known as the CXL® device (license number 77989) by ACCUTECH Medical Technologies Inc. has been licensed by Health Canada as a Class II device since September 19, 2008. An illumination device that emits homogeneous UVA, in combination with any generic form of riboflavin, is licensed by Health Canada for the indication to slow or stop the progression of corneal thinning caused by progressive keratectasia, iatrogenic keratectasia after laser-assisted in situ keratomileusis (LASIK) and pellucid marginal degeneration. The same device is named the UV-X® device by IROCMedical, with approvals in Argentina, the European Union and Australia. UVA devices all use light emitting diodes to generate UVA at a wavelength of 360-380 microns but vary in the number of diodes (5 to 25), focusing systems, working distance, beam diameter, beam uniformity and extent to which the operator can vary the parameters. In Ontario, CXL is currently offered at over 15 private eye clinics by refractive surgeons and ophthalmologists. The treatment is an outpatient procedure generally performed with topical anesthesia. The treatment consists of several well defined procedures. The epithelial cell layer is first removed, often using a blunt spatula in a 9.0 mm diameter under sterile conditions. This step is followed by the application of topical 0.1% riboflavin (vitamin B(2)) solution every 3 to 5 minutes for 25 minutes to ensure that the corneal stroma is fully penetrated. A solid-state UVA light source with a wavelength of 370 nm (maximum absorption of riboflavin) and an irradiance of 3 mW/cm(2) is used to irradiate the central cornea. Following treatment, a soft bandage lens is applied and prescriptions are given for oral pain medications, preservative-free tears, anti-inflammatory drops (preferably not nonsteroidal anti-inflammatory drugs, or NSAIDs) and antibiotic eye drops. Patients are recalled 1 week following the procedure to evaluate re-epithelialization and they are followed-up subsequently. A literature search was conducted on photochemical corneal collagen cross-linking with riboflavin (vitamin B(2)) and ultraviolet-A for the management of corneal thinning disorders using a search strategy with appropriate keywords and subject headings for CXL for literature published up until April 17, 2011. The literature search for this Health Technology Assessment (HTA) review was performed using the Cochrane Library, the Emergency Care Research Institute (ECRI) and the Centre for Reviews and Dissemination. The websites of several other health technology agencies were also reviewed, including the Canadian Agency for Drugs and Technologies in Health (CADTH) and the United Kingdom's National Institute for Clinical Excellence (NICE). The databases searched included OVID MEDLINE, MEDLINE IN-Process and other Non-Indexed Citations such as EMBASE. As the evidence review included an intervention for a rare condition, case series and case reports, particularly for complications and adverse events, were reviewed. A total of 316 citations were identified and all abstracts were reviewed by a single reviewer for eligibility. For those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. (ABSTRACT TRUNCATED)

Xerophthalmia in a traditional Quran boarding school in Sudan.

PubMed

Kheir, Abdelmoneim E M; Dirar, Tarig O M O; Elhassan, Haifa O M; Elshikh, Maha A H; Ahmed, Mohamed B M; Abbass, Mohammed A; Idris, Salma S

2012-01-01

To determine the prevalence of xerophthalmia at a traditional boarding school where children do not receive a diet adequate in vitamin A. A cross-sectional survey of 406 males residing in a Quranic traditional school was conducted using the World Health Organization xerophthalmia checklist. The association between the prevalence of night blindness and proportion of students staying at the school for 6 consecutive months and those eating solely at the school was investigated. The difference in age between children with night blindness and those without was investigated. Statistical significance was indicated by P<0.05. The prevalence of night blindness, conjunctival xerosis and Bitot's spots was 24%, 12.5% and 1%, respectively. None of the boys had corneal ulceration, corneal scars and corneal xerosis. No significant association was observed between the differences in mean age and development of night blindness (P=0.657). There was a significant association between the duration of stay (cut-off of 6 months continuously) at the institute and the development of night blindness (P=0.023). There was no statistical significance between regularly eating at the maseed and outside the "maseed" and the development of night blindness (P=0.75). Children residing at a traditional school are vulnerable to developing xerophthalmia where the diet is inadequate in vitamin A. Institutional caregivers should be made aware of the importance of providing a balanced diet rich in vitamin A. Institutional caregivers should also be educated on the signs and symptoms of vitamin A deficiency for early detection of xerophthalmia.

Can partial coherence interferometry be used to determine retinal shape?

PubMed

Atchison, David A; Charman, W Neil

2011-05-01

To determine likely errors in estimating retinal shape using partial coherence interferometric instruments when no allowance is made for optical distortion. Errors were estimated using Gullstrand no. 1 schematic eye and variants which included a 10 diopter (D) axial myopic eye, an emmetropic eye with a gradient-index lens, and a 10.9 D accommodating eye with a gradient-index lens. Performance was simulated for two commercial instruments, the IOLMaster (Carl Zeiss Meditec) and the Lenstar LS 900 (Haag-Streit AG). The incident beam was directed toward either the center of curvature of the anterior cornea (corneal-direction method) or the center of the entrance pupil (pupil-direction method). Simple trigonometry was used with the corneal intercept and the incident beam angle to estimate retinal contour. Conics were fitted to the estimated contours. The pupil-direction method gave estimates of retinal contour that were much too flat. The cornea-direction method gave similar results for IOLMaster and Lenstar approaches. The steepness of the retinal contour was slightly overestimated, the exact effects varying with the refractive error, gradient index, and accommodation. These theoretical results suggest that, for field angles ≤30°, partial coherence interferometric instruments are of use in estimating retinal shape by the corneal-direction method with the assumptions of a regular retinal shape and no optical distortion. It may be possible to improve on these estimates out to larger field angles by using optical modeling to correct for distortion.

The Palisades of Vogt in Congenital Corneal Opacification (An American Ophthalmological Society Thesis)

PubMed Central

Nischal, Ken K.; Lathrop, Kira L.

2016-01-01

Purpose The purposes of this study are first, to determine if the palisades of Vogt (POV) are present or absent in cases of congenital corneal opacification (CCO) by using spectral domain ocular coherence tomography (SD-OCT), and second, in those cases already undergoing penetrating keratoplasty (PKP), to see whether the absence or presence of POV corresponds to re-epithelialization following transplant. Methods This was a retrospective case review of 20 eyes (10 normal, 10 with CCO) evaluated with SD-OCT. The operator was masked to the clinician’s assessment of the ocular surface. In those cases where the decision to perform PKP had already been made, the correlation between POV presence or absence and posttransplant graft epithelialization was determined. Results All cases were imaged without adverse event. Nine eyes showed some evidence of POV and corresponding vasculature. Eight of 10 affected eyes underwent PKP, and subsequently 7 eyes epithelialized and 2 showed some peripheral neovascularization. The one eye that showed no signs of POV was the one that failed to epithelialize. All control subjects had consistent and regular POV. Conclusions Congenital corneal opacification is rare, and this study shows that at least some POV are present in the majority of cases of CCO. However, the palisades may not be entirely normal compared to age-matched controls. When there was absence of POV in a case of CCO, there was immediate and complete failure of epithelialization. PMID:28042184

Applications of corneal topography and tomography: a review.

PubMed

Fan, Rachel; Chan, Tommy Cy; Prakash, Gaurav; Jhanji, Vishal

2018-03-01

Corneal imaging is essential for diagnosing and management of a wide variety of ocular diseases. Corneal topography is used to characterize the shape of the cornea, specifically, the anterior surface of the cornea. Most corneal topographical systems are based on Placido disc that analyse rings that are reflected off the corneal surface. The posterior corneal surface cannot be characterized using Placido disc technology. Imaging of the posterior corneal surface is useful for diagnosis of corneal ectasia. Unlike corneal topographers, tomographers generate a three-dimensional recreation of the anterior segment and provide information about the corneal thickness. Scheimpflug imaging is one of the most commonly used techniques for corneal tomography. The cross-sectional images generated by a rotating Scheimpflug camera are used to locate the anterior and posterior corneal surfaces. The clinical uses of corneal topography include, diagnosis of corneal ectasia, assessment of corneal astigmatism, and refractive surgery planning. This review will discuss the applications of corneal topography and tomography in clinical practice. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Comparative randomised controlled clinical trial of a herbal eye drop with artificial tear and placebo in computer vision syndrome.

PubMed

Biswas, N R; Nainiwal, S K; Das, G K; Langan, U; Dadeya, S C; Mongre, P K; Ravi, A K; Baidya, P

2003-03-01

A comparative randomised double masked multicentric clinical trial has been conducted to find out the efficacy and safety of a herbal eye drop preparation, itone eye drops with artificial tear and placebo in 120 patients with computer vision syndrome. Patients using computer for at least 2 hours continuosly per day having symptoms of irritation, foreign body sensation, watering, redness, headache, eyeache and signs of conjunctival congestion, mucous/debris, corneal filaments, corneal staining or lacrimal lake were included in this study. Every patient was instructed to put two drops of either herbal drugs or placebo or artificial tear in the eyes regularly four times for 6 weeks. Objective and subjective findings were recorded at bi-weekly intervals up to six weeks. Side-effects, if any, were also noted. In computer vision syndrome the herbal eye drop preparation was found significantly better than artificial tear (p < 0.01). No side-effects were noted by any of the drugs. Both subjective and objective improvements were observed in itone treated cases. So, itone can be considered as a useful drug in computer vision syndrome.

Anterior ocular abnormalities of captive Asian elephants (Elephas maximus indicus) in Thailand.

PubMed

Kraiwong, Natapong; Sanyathitiseree, Pornchai; Boonprasert, Khajohnpat; Diskul, Phiphatanachatr; Charoenphan, Patara; Pintawong, Weerasak; Thayananuphat, Aree

2016-07-01

To survey and classify anterior ocular abnormalities in 1478 captive Asian elephants (Elephas maximus indicus) in six regions of Thailand. Anterior ocular examination was performed in both eyes (n = 2956) of 1478 elephants selected from the annual health check program involving 2958 animals within six regions of Thailand from January to November 2013. Lesions were described and compared between age and gender. A total of 17.83% (527/2956) of examined eyes from 24.97% (369/1478) of examined elephants had anterior ocular abnormalities. The most common lesions in these examined eyes were frothy ocular discharge (5.85%), corneal edema (5.31%), and conjunctivitis (5.18%). In addition, epiphora, phthisis bulbi, other corneal abnormalities, anterior uveitis, and lens abnormalities were noted. Almost all lesions increased in frequency with age (P < 0.01). Regular ophthalmic examination in elephants should be included in their annual health check program. Early detection and treatment of any ocular abnormality may avoid the development of subsequent irreversible ocular pathology. © 2015 American College of Veterinary Ophthalmologists.

Uneventful Anterior Migration of Intravitreal Ozurdex Implant in a Patient with Iris-Sutured Intraocular Lens and Descemet Stripping Automated Endothelial Keratoplasty

PubMed Central

Zafar, Andleeb; Aslanides, Ioannis M.; Selimis, Vasileios; Tsoulnaras, Konstantinos I.; Tabibian, David; Kymionis, George D.

2018-01-01

Purpose We report here the case of a patient with anterior segment migration of intravitreal dexamethasone implant as well as its management and outcome. Methods The patient had the following sequence of events: complicated cataract surgery, iris-sutured intraocular lens implant, followed by cystoid macular edema treated with intravitreal Avastin, retinal vein occlusion treated with intravitreal dexamethasone implant, corneal decompensation treated with Descemet stripping automated endothelial keratoplasty (DSAEK), and finally recurrence of macular edema treated with repeated intravitreal dexamethasone implant. Results Dexamethasone implant had completely dissolved from the eye 12 weeks after insertion without any complication. Conclusion A conservative approach with regular monitoring in the situation of a quiet anterior segment without any corneal decompensation can provide enough time for the implant to dissolve without causing any complication to the involved eye, avoiding any additional surgical intervention, as presented in this case report. Despite the fact that the implant was left for natural dissolution, there were no adverse effects related to the graft or the eye. PMID:29643797

Investigating the Short-term Effect of Eyelid Massage on Corneal Topography.

PubMed

Riede-Pult, Britta H; Evans, Katharine; Pult, Heiko

2017-06-01

The aim of this study was to evaluate the short-term effect of eyelid massage, after the use of warm compresses, on corneal topography. Corneal topography was evaluated on 20 subjects (mean age, 47.0 [SD ±17.3] years) using the Oculus Keratograph (Oculus, Wetzlar, Germany). Corneal eccentricity (Epsilon) was compared between topography measurements before eyelid warming (using warm compresses) (T1), after eyelid warming (T2), directly after eyelid massage (T3), and 30 minutes after eyelid massage (T4). Differences in corneal eccentricity between the enrolment measurement (T1) and consecutive measurements (T1-4) were analyzed. The contralateral eye-treated by warm compresses, but not by eyelid massage-was the control. Visual acuity (decimal), bulbar conjunctival hyperemia, and corneal staining (Cornea and Contact Lens Research Unit grading scale) were evaluated at T1 and T4 to assess clinical safety. No significant differences were found between consecutive eccentricity measurements overall and with the central radii (repeated-measures analysis of variance, P > .238 (massaged eyelid: Epsilon T1: 0.48 [95% confidence interval, ±0.07], T2: 0.49 [±0.05], T3: 0.49 [±0.06], T4: 0.48 [±0.06]; horizontal radii T1: 7.76 [±0.13] mm, T2: 7.74 [±0.13] mm, T3: 7.75 [±0.13] mm, T4: 7.76 [±0.13] mm; vertical radii T1: 7.56 [±0.12] mm, T2: 7.55 [±0.10] mm, T3: 7.54 [±0.10] mm, T4: 7.58 [±0.11] mm). Decimal visual acuity significantly improved at the end of the study (massaged eyelid: T1: 1.1 [±0.1]; T4: 1.3 [±0.1]; P < .032). No significant differences were detected between the consecutive evaluation of corneal staining (Wilcoxon test; P > .285). Redness was not significantly different between time points (repeated-measures analysis of variance; P = .187) in the colateral eyes. Hyperemia was significantly reduced in the massaged eyes (T1: 2.0 grade units [±0.3]; T4: 1.9 [±0.3]; P = .021). Eyelid warming followed by eyelid massage appears to be a safe procedure, without any clinically relevant short-term effects on the cornea.

Corneal hysteresis in patients with glaucoma-like optic discs, ocular hypertension and glaucoma.

PubMed

Murphy, Melissa L; Pokrovskaya, Olya; Galligan, Marie; O'Brien, Colm

2017-01-10

To compare corneal hysteresis (CH) measurements between patients with glaucoma, ocular hypertension (OHT) and glaucoma-like optic discs (GLD)- defined as a cup to disc ratio greater than or equal to 0.6 with normal intraocular pressure (IOP) and visual fields. The secondary aim was to investigate whether corneal resistance factor (CRF) and central corneal thickness (CCT) differ between patient groups. In this cross sectional study a total of 123 patients (one eye each) were recruited from a glaucoma outpatient department to undergo ocular response analyser (ORA) testing and ultrasound pachymetry as well as clinical examination. A One-way Analysis of Covariance (ANCOVA) was conducted to evaluate the mean difference in CH between the three diagnostic groups (glaucoma, OHT and GLD) correcting for potential confounding factors, IOP and age. Analysis was repeated for CRF and CCT. There was a significant difference in mean CH across the three diagnosis groups; F(2, 115) = 96.95; p < 0.001. Mean CH significantly higher for GLD compared to glaucoma (mean difference 1.83, p < 0.001), and significantly higher for OHT compared to glaucoma (mean difference 2.35, p < 0.001). Mean CH was slightly lower in patients with GLD than those with OHT but this difference was not statistically significant. A similar pattern was seen when the analysis was repeated for CRF and CCT. Higher CH in GLD and OHT compared to glaucoma suggests increased viscoelasticity of ocular tissues may have a protective role against glaucoma.

Eye bank survey of surgeons using precut donor tissue for descemet stripping automated endothelial keratoplasty.

PubMed

Kitzmann, Anna S; Goins, Kenneth M; Reed, Cynthia; Padnick-Silver, Lissa; Macsai, Marian S; Sutphin, John E

2008-07-01

To assess surgeon satisfaction with precut corneal tissue from 1 eye bank for Descemet stripping automated endothelial keratoplasty (DSAEK). Surgical techniques and predictors of procedural success were also examined. A 19-question survey was completed by 53 surgeons around the United States for 197 DSAEK cases using prepared corneal allograft tissue from the Iowa Lions Eye Bank. Surgeries were performed between April 1 and December 31, 2006; surveys were completed retrospectively within a few weeks of surgery. Tissue was found to be acceptable in 98% of DSAEK cases reported. Difficulties with precut tissue (eg, lack of anterior cap adherence to the posterior lamella, not visible or decentered central dot, anterior edge undermining) were reported in approximately 10% of cases. A rebubbling procedure was performed in 23% of cases for donor dislocations. The donor lenticule adhered, with resulting corneal deturgescence, in 86% of cases. Surgeons declared a successful procedure in 92% of cases. Of the 14 unsuccessful cases, donor tissue quality was the underlying etiology in only 1 case. Procedural success rates were related to surgeon experience (P = 0.002), lenticule adherence after only 1 anterior chamber air bubble (P = 0.005), no small perforations to release fluid (P = 0.005), and the presence of corneal deturgescence (P = 0.002). The use of precut tissue for DSAEK is not associated with increased risk of complications related to tissue preparation. With standardization of precutting donor tissue, safety of DSAEK surgery may be improved while increasing surgeon efficiency.

Matrix Metalloproteinase-8 Facilitates Neutrophil Migration through the Corneal Stromal Matrix by Collagen Degradation and Production of the Chemotactic Peptide Pro-Gly-Pro

PubMed Central

Lin, Michelle; Jackson, Patricia; Tester, Angus M.; Diaconu, Eugenia; Overall, Christopher M.; Blalock, J. Edwin; Pearlman, Eric

2008-01-01

Matrix metalloproteinase (MMP)-8 and MMP-9 play several roles in inflammation, including degradation of extracellular matrix (ECM) components and regulation of cytokine activity. To determine the roles of MMP-8 and MMP-9 in a neutrophil-dependent inflammatory response, we used a murine model of corneal inflammation in which LPS is injected into the corneal stroma. In contrast to wild-type mice, we found that i) lipopolysaccharide (LPS)-injected CXCR2−/− corneas had impaired neutrophil infiltration and did not express either MMP-8 or MMP-9; ii) neutrophil migration through the central cornea was impaired in Mmp8−/−, but not Mmp9−/−, mice; iii) neutrophil migration was inhibited in collagenase-resistant mice; iv) the chemotactic Pro-Gly-Pro (PGP) tripeptide that binds CXCR2 was decreased in CXCR2−/− mice; v) PGP production was impaired in Mmp8−/− corneas; and vi) neutralizing anti-PGP antibody did not inhibit neutrophil infiltration in Mmp8−/− mice. We found no effects of MMP-8 on LPS-induced CXC chemokine (LIX, or CXCL5)-induced neutrophil recruitment or on LPS-induced CXC chemokine production. Together, these studies indicate that neutrophils contribute to the production of both MMP-8 and MMP-9 in LPS-injected corneas and that MMP-8 regulates neutrophil migration through the dense collagenous ECM of the corneal stroma by generating chemotactic PGP during inflammation. PMID:18556780

Ocular inflammation in HLA-B27 transgenic mice reveals a potential role for MHC class I in corneal immune privilege.

PubMed

Lin, Aifeng; Guo, Xiaoxin; Inman, Robert D; Sivak, Jeremy M

2015-01-01

HLA-B27 is a major histocompatibility complex class I (MHCI) allele that has been closely associated with the development of ankylosing spondylitis and acute anterior uveitis (AAU), the most common form of uveitis worldwide. We have been characterizing the phenotypes of transgenic mice carrying a human HLA-B27 allele, but that are deficient in endogenous mouse MHCI genes (H-2K(-/-) and H-2D(-/-) double knockout, or DKO) to create the HLA-B27/DKO line. In maintaining and expanding this colony, we observed a rare sporadic severe central keratitis that developed in transgenic animals, but that was not present in wild-type (WT) animals. The corneas of affected HLA-B27/DKO and DKO mice were compared to their WT counterparts by staining with standard histological methods for markers of inflammation and neovascularization. A model of experimental corneal inflammation was subsequently used to test the responses of each genotype to insult. We identified a previously unreported corneal pathology in naïve HLA-B27/DKO mice, and we describe significantly prolonged CD4(+)- and CD8(+)-associated inflammation in these animals following an experimentally induced corneal injury. These results demonstrate an increased T-cell response in B27/DKO corneas due to the expression of the HLA-B27 allele, suggesting that low MHCI expression in WT corneas is an important contributor to immune privilege.

Toxic keratopathy associated with abuse of low-dose anesthetic: a case report.

PubMed

Chen, Hsiao-Ting; Chen, Ko-Hua; Hsu, Wen-Ming

2004-07-01

To describe the clinical course and treatment of toxic keratopathy associated with abuse of topical anesthetic at a very low concentration, 0.05%. Case report. A 47-year-old female systemic lupus erythematosus (SLE) patient with blurred vision and irritated right eye was referred to the ophthalmology department of our hospital. Under slit-lamp microscope, a 5.5 x 4.5 mm central corneal epithelial defect with underlying infiltrative and opaque stroma was noted in her right eye. Two weeks before, a corneal ulcer was diagnosed, and oxybuprocaine 0.05% (Lacrimin, Santen, Osaka, Japan) eye drops were prescribed 4 times daily but used every 5 to 10 minutes because the right eye was severely irritated. She was admitted immediately under the impression of toxic corneal ulcer. Preservative-free lubricants and prophylactic topical antibiotics 4 times daily were applied. Therapeutic soft contact lens was started after no infective agents were detected. Two weeks later, the stromal infiltration subsided, and the corneal epithelium was slowly healing, but superficial punctate epithelial defects at the lesion site persisted for another 6 months. The vision of her right eye improved from finger-counting at a 30-cm distance to 20/1200 with correction. Toxic keratopathy may result from abuse of topically administered anesthetics even at a very low concentration, 0.05%. Because this SLE patient has tear problems, we suggest that topical anesthetics must be used very cautiously and never prescribed to patients with dry eyes where the integrity of ocular surface is altered.

Measurement centration and zone diameter in anterior, posterior and total corneal astigmatism in keratoconus.

PubMed

Fredriksson, Anneli; Behndig, Anders

2017-12-01

To investigate the central and paracentral astigmatism and the significance of centration and measurement zone diameter compared to a 3-mm pupil-centred measurement zone in keratoconus and in healthy eyes. Twenty-eight right eyes from 28 KC patients with an inferotemporal cone were selected according to specified criteria based on Oculus Pentacam HR ® measurements and were matched with healthy control eyes. The flat (K1) and steep (K2) keratometry readings were registered from the 'Total Corneal Refractive Power' (TCRP) display as well as the anterior and posterior corneal astigmatism displays (ACA and PCA, respectively). Astigmatic power vectors KP0 and KP45 were calculated and analysed for a 6-mm and two 3-mm zones centred on the corneal apex and the pupil, and for 8 paracentral 3-mm zones. The astigmatism was generally higher in KC. Many astigmatic values in KC differed between the 3-mm pupil-centred and the 3- and 6-mm apex-centred zones in KC. In the controls, no corresponding differences between measurement zones were seen, apart from PCA, which differed. The magnitude and direction of KP0 and KP45 varied greatly between the paracentral measurements in KC. Centration and measurement zone diameter have great impacts on the astigmatic values in KC. A small pupil-centred measurement zone should be considered when evaluating the astigmatism in KC. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Corneal endothelial morphology and function after torsional and longitudinal ultrasound mode phacoemulsification.

PubMed

Módis, László Jr; Szalai, Eszter; Flaskó, Zsuzsa; Németh, Gábor

2016-01-01

To study the endothelial cell morphology and corneal thickness changes after phacoemulsification by using the OZil torsional and longitudinal ultrasound techniques (Infiniti Vision System, Alcon Laboratories). Department of Ophthalmology, Clinical Center, University of Debrecen, Debrecen, Hungary. 52 patients with cataract were randomly assigned to longitudinal ultrasound and torsional mode group. All surgeries were performed through a 2.2 mm clear corneal incision, the method employed being divide and conquer. The endothelial morphometry such as cell density (ECD), mean cell area, coefficient of variation of cell area, and central corneal thickness were examined with specular microscopy (EM-1000, Tomey) preoperatively and 4, 8 weeks postoperatively. ECD values decreased significantly in both surgical groups (P < .001, repeated- mesures ANOVA), the postoperative endothelial cell loss was higher in the longitudinal ultrasound mode group (3.5% and 6.5%, at 4 and 8 weeks after surgery) than in the torsional group (3.3% and 5.5%, at 4 and 8 weeks after surgery), the difference not being significant between the two groups (P = .164 and P = .479, at 4 and 8 weeks after surgery, Mann-Whitney test). There was no statistically significant difference in any of the assessed parameters between the two surgical groups (P > .05). No significant correlation was found between the endothelial cell loss and the nucleus density. Both phacoemulsification techniques were safe and effective. The torsional handpiece performs oscillatory movements and delivers less energy into the eye than the longitudinal ultrasound technique, therefore providing more favorable energy and thermal safety profile.

Biomechanical and optical behavior of human corneas before and after photorefractive keratectomy.

PubMed

Sánchez, Paolo; Moutsouris, Kyros; Pandolfi, Anna

2014-06-01

To evaluate numerically the biomechanical and optical behavior of human corneas and quantitatively estimate the changes in refractive power and stress caused by photorefractive keratectomy (PRK). Athineum Refractive Center, Athens, Greece, and Politecnico di Milano, Milan, Italy. Retrospective comparative interventional cohort study. Corneal topographies of 10 human eyes were taken with a scanning-slit corneal topographer (Orbscan II) before and after PRK. Ten patient-specific finite element models were created to estimate the strain and stress fields in the cornea in preoperative and postoperative configurations. The biomechanical response in postoperative eyes was computed by directly modeling the postoperative geometry from the topographer and by reproducing the corneal ablation planned for the PRK with a numerical reprofiling procedure. Postoperative corneas were more compliant than preoperative corneas. In the optical zone, corneal thinning decreased the mechanical stiffness, causing local resteepening and making the central refractive power more sensitive to variations in intraocular pressure (IOP). At physiologic IOP, the postoperative corneas had a mean 7% forward increase in apical displacement and a mean 20% increase in the stress components at the center of the anterior surface over the preoperative condition. Patient-specific numerical models of the cornea can provide quantitative information on the changes in refractive power and in the stress field caused by refractive surgery. 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.

Corneal endothelial cell density and morphology in patients with acromegaly.

PubMed

Hatipoglu, Esra; Arici, Ceyhun; Arslan, Osman Sevki; Dikkaya, Funda; Sultan, Pinar; Kadioglu, Pinar; Gundogdu, Sadi

2014-12-01

Acromegaly has various impacts on many organs. The ophthalmologic effects of acromegaly have not yet been investigated in detail. The aim of the current study was to evaluate qualitative and quantitative changes in corneal endothelial cells and central corneal thickness (CCT) of the patients with acromegaly. In this prospective, cross-sectional study, 128 eyes of 64 patients with acromegaly (female/male=40/24) and 208 eyes of 104 age and gender-matched healthy volunteers (female/male=69/35) were included. Endothelial cell density (ECD), cellular area (CA), coefficient of variation (CV) in cell size, percentage of hexagonal cells, and CCT were measured in patients with acromegaly and in healthy volunteers using the noncontact specular microscopy (SP-3000P: Topcon Corporation, Tokyo, Japan). ECD and CA were lower in cases with acromegaly than in controls (ECD in acromegaly: 2615.65 cell/mm(2) and in controls: 2700.35 cell/mm(2); p=0.002. CA in acromegaly: 382.30μm(2) and in controls: 400.30μm(2); p=0.02). In the entire group with acromegaly, the time elapsed since diagnosis was positively correlated with CA and was negatively correlated with ECD (r=+0.39, p=0.001 and r=-0.42, p=0.001). The endothelial layer of the cornea may be under risk of impairment with prolonged disease duration in acromegaly. Consistency of the corneal endothelium should be also sought during long-term follow-up of the cases with acromegaly. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

Regional assessment of energy-producing metabolic activity in the endothelium of donor corneas.

PubMed

Greiner, Mark A; Burckart, Kimberlee A; Wagoner, Michael D; Schmidt, Gregory A; Reed, Cynthia R; Liaboe, Chase A; Flamme-Wiese, Miles J; Zimmerman, M Bridget; Mullins, Robert F; Kardon, Randy H; Goins, Kenneth M; Aldrich, Benjamin T

2015-05-01

We characterized mitochondrial respiration and glycolysis activity of human corneal endothelium, and compared metabolic activity between central and peripheral regions. Endothelial keratoplasty-suitable corneas were obtained from donors aged 50 to 75 years. The endothelium-Descemet membrane complex (EDM) was isolated, and 3-mm punches were obtained from central and peripheral regions. Endothelium-Descemet membrane punches were assayed for mitochondrial respiration (oxygen consumption) and glycolysis (extracellular acidification) using an extracellular flux analyzer. Enzymatic (citrate synthase, glucose hexokinase) and mitochondrial density (MitoTracker) assays also were performed. Ten corneas were analyzed per assay. Metabolic activity for mitochondrial respiration and glycolysis showed expected changes to assay compounds (P < 0.01, all pairwise comparisons). Basal mitochondrial respiration and glycolysis activity did not differ between regions (P > 0.99). Similarly, central versus peripheral activity after assay compound treatment showed no significant differences (P > 0.99, all time points). The intracorneal coefficient of variation for basal readings between two and four peripheral punches was 18.5% of the mean. Although peripheral samples displayed greater enzymatic activity than central samples (P < 0.05), similar to extracellular flux results, mitochondrial density did not differ between regions (P = 0.78). Extracellular flux analysis of oxygen and pH is a valid technique for characterizing metabolic activity of human corneal endothelium. This technique demonstrates high reproducibility, allows quantification of metabolic parameters using small quantities of live cells, and permits estimation of overall metabolic output. Neither oxygen consumption nor extracellular acidification differed between central and peripheral regions of transplant suitable corneas in this series. Our results show that endothelial cell health can be quantified biochemically in transplant suitable corneas.

The relationship between central corneal thickness and optic disc size in patients with primary open-angle glaucoma in a hospital-based population.

PubMed

Terai, Naim; Spoerl, Eberhard; Pillunat, Lutz E; Kuhlisch, Eberhard; Schmidt, Eckart; Boehm, Andreas G

2011-09-01

To investigate the relationship between central corneal thickness (CCT) and optic disc size in patients with primary open-angle glaucoma (POAG) in a hospital-based population. Data for the right eyes of 1435 White patients with POAG were included in a retrospective hospital-based study. All eyes underwent optic nerve head imaging using Heidelberg Retina Tomograph II (HRT II; Heidelberg Engineering, Heidelberg, Germany) and CCT measurement by ultrasound corneal pachymetry. Eyes with prior intraocular or corneal surgery were excluded. Low-quality HRT II images were also excluded. The impact of age, gender, CCT, intraocular pressure, cylindrical and spherical refractive error as independent factors on optic disc size was investigated in a multiple linear regression analysis. The data for 1104 right eyes qualified for participation in the study. The median age of these patients was 65 years. The median CCT was 547 μm (25th-75th percentile 522-575 μm). The median optic disc size was 2.21 mm(2) (25th-75th percentile 1.89-2.60 mm(2)). Multiple linear regression analysis revealed that age (p = 0.001), CCT (p = 0.001) and spherical equivalent (p = 0.049) were correlated to disc size according to the following formula: disc area = -0.004 × age - 0.001 × CCT - 0.014 × spherical equivalent +3.290. R(2) of the whole model was 0.021. Univariate regression analysis between age and disc area provided R(2) = 0.008 with p = 0.002. Univariate regression analysis between disc area and CCT provided R(2) = 0.005 with p = 0.02. In this retrospective hospital-based study we could not detect a clinically relevant correlation between optic disc size and CCT. The correlation between CCT and disc size and between age and disc size were statistically significant, but the R(2) values were very low. The results of the study are biased because of its hospital-based design, so the results of the study need to be confirmed in a large population-based study. © 2009 The Authors. Journal compilation © 2009 Acta Ophthalmol.

[Comparison of the anterior corneal asphericity after small incision lenticule extraction and femtosecond laser in situ keratomileusis].

PubMed

Su, X L; Wang, Y; Wu, W J; Wu, Z Q; Wu, Y N; Yu, C J

2016-09-11

To evaluate and compare the anterior corneal asphericity after small incision lenticule extraction(SMILE)and femtosecond laser in situ keratomileusis(FS-LASIK). In this case-control study, 45 subjects who underwent SMILE operation comprised the study group, and 33 subjects with FS-LASIK operation comprised the control group. The asphericity coefficient Q-value of the right eyes in both groups was measured at diameters of 6, 7, 8 and 9 mm, respectively, before surgery and at 1 day, 1 week, 1 month and 6 months following surgery. The correlation between the variation of Q-value and the central cutting depth was analyzed. The Q-value of anterior corneal surface was 0.85 ± 0.31, 0.80±0.28, 0.69±0.25 and 0.51±0.23 after SMILE, and 1.13±0.56, 1.01±0.47, 0.80±0.39 and 0.51±0.31 after FS-LASIK at 1 week. In both groups, the Q-value was significantly different before and after surgery(P< 0.05); there were interaction effects between the operation method and time; the difference between the two groups at 6-mm and 7-mm diameters was statistically significant(P<0.05). The variation of the Q-value before and after operation(ΔQ)showed significant difference(P6mm=0.004, P7mm=0.014)between the two groups at 6-mm and 7-mm diameters. The cap diameter of the SMILE group was smaller than that of the FS-LASIK group, but the cutting depth was larger. There was no correlation between ΔQ and the cap/disc diameter. It showed a linear relationship(P<0.05)between ΔQ and the central cutting depth at all examined diameters in the two groups, and the relation degree in the FS-LASIK group was superior to the SMILE group. Both SMILE and FS-LASIK operations can change the negative Q-value of the anterior corneal surface to the positive. The impact of SMILE on the asphericity is smaller than that of FS-LASIK. (Chin J Ophthalmol, 2016, 52: 681-685).

Fitting an MSD (mini scleral design) rigid contact lens in advanced keratoconus with INTACS.

PubMed

Dalton, Kristine; Sorbara, Luigina

2011-12-01

Keratoconus is a bilateral degenerative disease characterized by a non-inflammatory, progressive central corneal ectasia (typically asymmetric) and decreased vision. In its early stages it may be managed with spectacles and soft contact lenses but more commonly it is managed with rigid contact lenses. In advanced stages, when contact lenses can no longer be fit, have become intolerable, or corneal damage is severe, a penetrating keratoplasty is commonly performed. Alternative surgical techniques, such as the use of intra-stromal corneal ring segments (INTACS) have been developed to try and improve the fit of rigid contact lenses in keratoconic patients and avoid penetrating keratoplasties. This case report follows through the fitting of rigid contact lenses in an advanced keratoconic cornea after an INTACS procedure and discusses clinical findings, treatment options, and the use of mini-scleral and scleral lens designs as they relate to the challenges encountered in managing such a patient. Mini-scleral and scleral lenses are relatively easy to fit, and can be of benefit to many patients, including advanced keratoconic patients, post-INTAC patients and post-penetrating keratoplasty patients. 2011 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Epilation for Minor Trachomatous Trichiasis: Four-Year Results of a Randomised Controlled Trial

PubMed Central

Habtamu, Esmael; Rajak, Saul N.; Tadesse, Zerihun; Wondie, Tariku; Zerihun, Mulat; Guadie, Birhan; Gebre, Teshome; Kello, Amir Bedri; Callahan, Kelly; Mabey, David C. W.; Khaw, Peng T.; Gilbert, Clare E.; Weiss, Helen A.; Emerson, Paul M.; Burton, Matthew J.

2015-01-01

Background Trachomatous trichiasis (TT) needs to be managed to reduce the risk of vision loss. The long-term impact of epilation (a common traditional practice of repeated plucking of lashes touching the eye) in preventing visual impairment and corneal opacity from TT is unknown. We conducted a randomized controlled trial of epilation versus surgery for the management of minor TT (fewer than six lashes touching the eye) in Ethiopia. Here we report the four-year outcome and the effect on vision and corneal opacity. Methodology/ Principal Findings 1300 individuals with minor TT were recruited and randomly assigned to quality trichiasis surgery or repeated epilation using high quality epilation forceps by a trained person with good near vision. Participants were examined six-monthly for two-years, and then at four-years after randomisation. At two-years all epilation arm participants were offered free surgery. At four-years 1151 (88.5%) were re-examined: 572 (88%) and 579 (89%) from epilation and surgery arms, respectively. At that time, 21.1% of the surgery arm participants had recurrent TT; 189/572 (33%) of the epilation arm had received surgery, while 383 (67%) declined surgery and had continued epilating (“epilation-only”). Among the epilation-only group, 207 (54.1%) fully controlled their TT, 166 (43.3%) had minor TT and 10 (2.6%) had major TT (>5 lashes). There were no differences between participants in the epilation-only, epilation-to-surgery and surgery arm participants in changes in visual acuity and corneal opacity between baseline and four-years. Conclusions/ Significance Most minor TT participants randomised to the epilation arm continued epilating and controlled their TT. Change in vision and corneal opacity was comparable between surgery and epilation-only participants. This suggests that good quality epilation with regular follow-up is a reasonable second-line alternative to surgery for minor TT for individuals who either decline surgery or do not have immediate access to surgical treatment. PMID:25768796

Corneal Curvature, Astigmatism, and Aberrations in Marfan Syndrome with Lens Subluxation: Evaluation by Pentacam HR System.

PubMed

Chen, Jiahui; Jing, Qinghe; Tang, Yating; Qian, Dongjin; Lu, Yi; Jiang, Yongxiang

2018-03-06

Marfan syndrome (MFS) is associated with abnormalities of corneal biometric characteristics. We conducted a retrospective case-control study including 55 eyes of the MFS patients with lens subluxation and 53 normal eyes of the control subjects to evaluate the corneal curvature, astigmatism and aberrations using a rotating Scheimpflug camera (Pentacam HR). Compared with the control group, the anterior, posterior, and total corneal curvature were flatter in the MFS group. The anterior and total corneal astigmatism were higher in the MFS patients, whereas the posterior corneal astigmatism was not significantly different between the two groups. Regarding the total corneal aberrations, the root mean square (RMS) aberrations, RMS higher-order aberrations and RMS lower-order aberrations increased, whereas the spherical aberration decreased in the MFS patients. Corneal parameters had potential diagnostic values for MFS patients with lens subluxation and the more reasonable cutoffs were the values of corneal curvature <41.35 D, corneal astigmatism >0.85 D and spherical aberration <0.188 μm. Corneal biometric characteristics of MFS patients with lens subluxation include decreased corneal curvature, higher corneal astigmatism, larger corneal aberrations, and lower spherical aberration. Corneal curvature, corneal astigmatism, and spherical aberration are better diagnostic tools for suspicious MFS.

Glaucoma and increased central corneal thickness in aphakic and pseudophakic patients after congenital cataract surgery

PubMed Central

Simsek, T; Mutluay, A H; Elgin, U; Gursel, R; Batman, A

2006-01-01

Aim To compare the mean central corneal thickness (CCT) among aphakic and pseudophakic patients following congenital cataract surgery with age matched controls. Methods This study included 43 eyes of 43 aphakic and pseudophakic patients following congenital cataract surgery. 44 healthy, age and sex matched volunteers were recruited for comparison with the patients. After a complete eye examination, corneal thickness and intraocular pressure were measured. Results In the study group, 33 eyes were aphakic, and the remaining 10 eyes were pseudophakic. The median CCT was 556.0 μm (range 490–640 μm) in the control group and 626 μm (range 523–870 μm) in the study group (p<0.05). There was a significant difference in CCT between aphakic and pseudophakic eyes in which an intraocular lens (IOL) had been implanted at the time of congenital cataract surgery (p = 0.011). The same difference was not observed between aphakic and pseudophakic eyes in which an IOL had been implanted secondarily (p = 0.835). The median age of the patients at the time of lensectomy was 24 months (range 1 week to 120 months). There was a negative correlation between the age at lensectomy and CCT (r = −0.485, p = 0.001). Conclusion Aphakic and pseudophakic patients have significantly thicker corneas than age matched controls. This difference can have an important effect on interpreting intraocular pressures in these patients. It is also important to assess the effects of early surgery for congenital cataracts, as well as those of primary and secondary IOL implantation, on CCT. PMID:16707519

Local Variability of Parameters for Characterization of the Corneal Subbasal Nerve Plexus.

PubMed

Winter, Karsten; Scheibe, Patrick; Köhler, Bernd; Allgeier, Stephan; Guthoff, Rudolf F; Stachs, Oliver

2016-01-01

The corneal subbasal nerve plexus (SNP) offers high potential for early diagnosis of diabetic peripheral neuropathy. Changes in subbasal nerve fibers can be assessed in vivo by confocal laser scanning microscopy (CLSM) and quantified using specific parameters. While current study results agree regarding parameter tendency, there are considerable differences in terms of absolute values. The present study set out to identify factors that might account for this high parameter variability. In three healthy subjects, we used a novel method of software-based large-scale reconstruction that provided SNP images of the central cornea, decomposed the image areas into all possible image sections corresponding to the size of a single conventional CLSM image (0.16 mm2), and calculated a set of parameters for each image section. In order to carry out a large number of virtual examinations within the reconstructed image areas, an extensive simulation procedure (10,000 runs per image) was implemented. The three analyzed images ranged in size from 3.75 mm2 to 4.27 mm2. The spatial configuration of the subbasal nerve fiber networks varied greatly across the cornea and thus caused heavily location-dependent results as well as wide value ranges for the parameters assessed. Distributions of SNP parameter values varied greatly between the three images and showed significant differences between all images for every parameter calculated (p < 0.001 in each case). The relatively small size of the conventionally evaluated SNP area is a contributory factor in high SNP parameter variability. Averaging of parameter values based on multiple CLSM frames does not necessarily result in good approximations of the respective reference values of the whole image area. This illustrates the potential for examiner bias when selecting SNP images in the central corneal area.

Ethnic Variations in Central Corneal Thickness in a Rural Population in China: The Yunnan Minority Eye Studies.

PubMed

Pan, Chen-Wei; Li, Jun; Zhong, Hua; Shen, Wei; Niu, Zhiqiang; Yuan, Yuansheng; Chen, Qin

2015-01-01

To describe the ethnic differences in central corneal thickness (CCT) in population-based samples of ethnic Bai, Yi and Han people living in rural China. 6504 adults (2119 ethnic Bai, 2202 ethnic Yi and 2183 ethnic Han) aged 50 years or older participated in the study. Each subject underwent standardized ocular examinations and interviewer-administered questionnaires for risk factor assessment. CCT was measured for both eyes using an ultrasound pachymeter. Regression and principal component analysis were performed to examine the relationship of ethnicity and other factors with CCT. The mean CCT readings were 536.4 ± 34.2 μm in ethnic Bai, 532.1 ± 32.1 μm in ethnic Yi and 529.6 ± 32.7 μm in ethnic Han adults (P<0.001), respectively. There was a decreasing trend of mean CCT with increasing age across all ethnic groups. In multivariate linear regression models, increasing CCT was associated with younger age (P<0.001), male gender (P<0.001), Bai (P<0.001) or Yi (P<0.001) ethnicity, greater body mass index (P<0.001), higher systolic blood pressure (P<0.001), greater corneal curvature (P<0.001), deeper anterior chamber (P < 0.001), and thicker lens (P<0.001). Ethnicity contributed significantly to presence of thin cornea (60%; P< 0.001) compared with other factors. CCT had similar impact on intraocular pressure readings across all ethnic groups. This study of more than 6500 multiethnic participants demonstrates significant ethnic variations in CCT, with Han ethnicity having the thinnest cornea compared with ethnic minorities. These data are essential to guide future multiethnic clinical trials on CCT-related ocular conditions such as glaucoma.

A medieval fallacy: the crystalline lens in the center of the eye.

PubMed

Leffler, Christopher T; Hadi, Tamer M; Udupa, Akrithi; Schwartz, Stephen G; Schwartz, Daniel

2016-01-01

To determine whether, as most modern historians have written, ancient Greco-Roman authors believed the crystalline lens is positioned in the center of the eye. Historians have written that statements about cataract couching by Celsus, or perhaps Galen of Pergamon, suggested a centrally located lens. Celsus specifically wrote that a couching needle placed intermediate between the corneal limbus and the lateral canthus enters an empty space, presumed to represent the posterior chamber. Ancient ophthalmic literature was analyzed to understand where these authors believed the crystalline lens was positioned. In order to estimate where Celsus proposed entering the eye during couching, we prospectively measured the distance from the temporal corneal limbus to the lateral canthus in 30 healthy adults. Rufus of Ephesus and Galen wrote that the lens is anterior enough to contact the iris. Galen wrote that the lens equator joins other ocular structures at the corneoscleral junction. In 30 subjects, half the distance from the temporal corneal limbus to the lateral canthus was a mean of 4.5 mm (range: 3.3-5.3 mm). Descriptions of couching by Celsus and others are consistent with pars plana entry of the couching needle. Anterior angulation of the needle would permit contact of the needle with the lens. Ancient descriptions of anatomy and couching do not establish the microanatomic relationships of the ciliary region with any modern degree of accuracy. Nonetheless, ancient authors, such as Galen and Rufus, clearly understood that the lens is located anteriorly. There is little reason to believe that Celsus or other ancient authors held a variant understanding of the anatomy of a healthy eye. The notion of the central location of the lens seems to have arisen with Arabic authors in 9th century Mesopotamia, and lasted for over 7 centuries.

Contact lens management of irregular corneas after traumatic aphakia: A pediatric case series.

PubMed

Aung, Yin-Yin; McLeod, Andrew

2015-10-01

Pediatric patients account for 35% of all cases that present after ocular trauma and 20.9% of those result in a ruptured globe. When repairing the globe, the removal of the natural lens results in a significant change in refractive error and loss of accommodation. In addition, the eye can have scarring, irregular astigmatism, and changes to the ocular surface. Treatment and vision rehabilitation should be aggressive and done quickly to prevent amblyopia. Advanced lens designs are often needed to treat both the irregular ocular surface and the aphakia. Treatment options are often confounded with the usual issues of contact lens compliance, intolerance, and complications. This case series follows three aphakic pediatric patients through the contact lens fitting process after sustaining a ruptured globe that left them aphakic with residual irregular astigmatism and corneal scarring. Patient 1 is a 3-year-old Hispanic male fit with a bitoric gas permeable contact lens with irregular astigmatism and an elevated central corneal scarring. Patient 2 is a 12-year-old Caucasian male with minimal residual astigmatism fit in a multifocal soft contact lens. Patient 3 is an 8-year-old African American male fit with a hybrid contact lens that was needed to vault the irregular astigmatism and central corneal scarring. Treating patients with irregular corneas or aphakia can be challenging in their own right, but in combination are some of the most advanced specialty contact lens fittings. This case series followed three pediatric patients through the fitting process and demonstrated the options and challenges when fitting this unique patient population. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

In Vivo Confocal Microscopic Evaluation of Corneal Langerhans Cells in Dry Eye Patients§

PubMed Central

Machetta, Federica; Fea, Antonio M; Actis, Alessandro G; de Sanctis, Ugo; Dalmasso, Paola; Grignolo, Federico M

2014-01-01

Purpose. To assess inflammatory involvement of cornea in dry eye by means of confocal microscopy, evaluating the presence and distribution of Langherans cells (LCs). Methods: 98 eyes of 49 subjects were enrolled: 18 subjects affected by Sjögren Syndrome Dry Eye (SSDE), 17 with Non-Sjögren Syndrome Dry Eye (NSSDE), 14 healthy volunteeers. Dry eye symptoms, tear film, ocular surface damage and corneal confocal microscopy were analized. Results: A significant increase of LCs density was observed at sub-basal nerve plexus (SSDE = 79 cells/mm2 andNDE = 22 cells/mm2; p = 0,0031) and sub-epithelial nerve plexus (SSDE = 38 cells/mm2 and NDE = 3 cells/mm2; p = 0,0169) in central cornea of SSDE group. An increased number of LCs from the center to the periphery of the cornea was observed, significant only in healthy volunteers group. In dry eye patients there was an increase in LCs density in both peripheral and central cornea with a significant difference between NDE (14,66 cells/mm2) and SSDE (56,66 cells/mm2) only in central cornea (p = 0,0028). In SSDE group, mean density of LCs in central cornea results also superior to NSSDE group (29,33 cells/mm2). There was no correlation between LCs density and dry eye symptoms, tear film deficiency and ocular surface damage. Conclusion: This study demonstrates the activation of an inflammatory and immunological reaction in cornea of NSSDE and SSDE patients. Confocal microscopy can be an important diagnostic tool in evaluation and follow-up of dry eye disease. PMID:25317216

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.

Critical review on refractive surgical lasers

NASA Astrophysics Data System (ADS)

Lin, J. T.

1995-03-01

The current status of refractive surgical lasers (including excimer and nonexcimer lasers) is reviewed with an emphasis on photorefractive keratectomy (PRK). The correlation of engineering parameters and the clinical requirements with optimal conditions are presented. The fundamentals of corneal reshaping with formulas for ablation profiles and the advantages of the multizone method are discussed. Updated information on the Mini-Excimer PRK laser system, with an emphasis on the scanning delivery device, is presented. PMMA ablation profiles performed by standard diaphragm and scanning modes are compared for surface ablation quality. Scanning mode ablation patterns for myopia, hyperopia, and regular and irregular astigmatism are presented.

Clinical Outcomes after Keraring Implantation for Keratoconus Management in Patients Older Than 40 Years: A Retrospective, Interventional, Cohort Study.

PubMed

Gatzioufas, Zisis; Khine, Aye; Elalfy, Mohamed; Guber, Ivo; McLintock, Cameron; Sabatino, Francesco; Hamada, Samer; Lake, Damian

2018-06-01

Intracorneal ring segment implantation is an effective and safe method of visual improvement in patients with keratoconus. The aim of our study was to evaluate the long-term clinical outcomes after Keraring implantation for keratoconus in patients older than 40 years. Eleven eyes from 11 patients with keratoconus who underwent femtosecond laser-assisted Keraring implantation for keratoconus were included in this retrospective study. The uncorrected visual acuity (UCVA), corrected visual acuity, keratometric readings, central corneal thickness and thinnest corneal pachymetry were evaluated preoperatively and 6 months after the Keraring implantation. UCVA, BCVA and keratometric readings improved at 6 months postoperatively. Our data showed significant keratometric amelioration and visual improvement after Keraring implantation for keratoconus in patients older than 40 years at 6 months postoperatively.

A minimal model of epithelial tissue dynamics and its application to the corneal epithelium

NASA Astrophysics Data System (ADS)

Henkes, Silke; Matoz-Fernandez, Daniel; Kostanjevec, Kaja; Coburn, Luke; Sknepnek, Rastko; Collinson, J. Martin; Martens, Kirsten

Epithelial cell sheets are characterized by a complex interplay of active drivers, including cell motility, cell division and extrusion. Here we construct a particle-based minimal model tissue with only division/death dynamics and show that it always corresponds to a liquid state with a single dynamic time scale set by the division rate, and that no glassy phase is possible. Building on this, we construct an in-silico model of the mammalian corneal epithelium as such a tissue confined to a hemisphere bordered by the limbal stem cell zone. With added cell motility dynamics we are able to explain the steady-state spiral migration on the cornea, including the central vortex defect, and quantitatively compare it to eyes obtained from mice that are X-inactivation mosaic for LacZ.

Association between culture results of corneal scrapings and culture and histopathology results of corneal tissues in therapeutic keratoplasty.

PubMed

Das, Sujata; Sharma, Savitri; Priyadarshini, Omega; Sahu, Srikant K; Kar, Sarita; Vemuganti, Geeta K

2011-09-01

To correlate the culture results of corneal scrapings with culture and histopathology results of corneal tissues in therapeutic keratoplasty. A retrospective analysis of the culture results of corneal scrapings and corneal tissues of eyes that received therapeutic penetrating keratoplasty at a tertiary eye care center between December 2006 and November 2008 was conducted. As per the preferred practice, those cases that did not respond to appropriate antimicrobial therapy and/or presented with a large infiltrate/perforation received therapeutic keratoplasty. The microbiology and histopathology findings of the corneal tissues were compared. Thirty-eight therapeutic keratoplasties were performed on 36 patients. Although all cases had histopathology and culture of the corneal tissue, corneal scrapings were not performed in 4 cases. Corneal scrapings and corneal tissues were culture-positive in 76% (26 of 34) and 60% (23 of 38) of cases, respectively. In 8 cases, the corneal scrapings and corneal tissues yielded identical organisms, whereas different organisms grew in 4 cases. In 6 cases, the corneal tissues were culture-positive but the corneal scrapings were sterile. In 20 cases, the corneal tissues were culture-positive for fungus and also showed fungal filaments in their corresponding histopathology specimens. Corneal tissue culture can provide additional information in cases undergoing therapeutic keratoplasty. It helps to determine the management of patients after keratoplasty.

New central configurations of the (n + 1) -body problem

NASA Astrophysics Data System (ADS)

Fernandes, Antonio Carlos; Garcia, Braulio Augusto; Llibre, Jaume; Mello, Luis Fernando

2018-01-01

In this article we study central configurations of the (n + 1) -body problem. For the planar (n + 1) -body problem we study central configurations performed by n ≥ 2 bodies with equal masses at the vertices of a regular n-gon and one body with null mass. We also study spatial central configurations considering n bodies with equal masses at the vertices of a regular polyhedron and one body with null mass.

Infrared ocular thermography in dogs with and without keratoconjunctivitis sicca.

PubMed

Biondi, Flávia; Dornbusch, Peterson T; Sampaio, Manuella; Montiani-Ferreira, Fabiano

2015-01-01

Infrared thermography was used to measure temperature differences of the corneal surface between nasal and temporal limbus regions and central cornea of normal dogs and dogs with keratoconjunctivitis sicca (KCS), in order to establish temperature values in normal canine eyes and in patients with decreased Schirmer tear tests (STT) values. Dogs investigated were all either patients seen at the Veterinary Teaching Hospital of Federal University of Paraná or normal dogs that belonged to the same institution. STT were performed in all eyes. A total of 40 control eyes (STT ≥15 mm/min) and 20 eyes with low STT values (STT ≤14 mm/min) were examined. The mean STT value for eyes with normal STT values was 22.9 ± 3.9 mm/min (mean ± standard deviation), and the mean STT value for eyes with low STT value was 7.2 ± 4.8 mm/min. The mean corneal temperature was significantly lower in eyes with low STT values than in control eyes (P < 0.0001). The following significant correlations were found: (i) Schirmer and breakup time (BUT) (P = 0.0001, r = 0.5); (ii) STT values and corneal surface temperature (P = 0.001, r = 0.256); (iii) STT values and age (P = 0.0001, r = -0.448); (iv) age and corneal surface temperature (P = 0.0001, r = -0.281); and (v) BUT and corneal surface temperature (P = 0.0001, r = 0.36). Thermography is a method that can differentiate between eyes with normal and abnormal STT values. In the future, thermography might be incorporated as part of the ophthalmic examination and perhaps become a popular ancillary test for the diagnoses of ocular surface disorders. © 2013 American College of Veterinary Ophthalmologists.

Evaluation of the adhesive properties of the cornea by means of optical coherence tomography in patients with meibomian gland dysfunction and lacrimal tear deficiency.

PubMed

Napoli, Pietro Emanuele; Coronella, Franco; Satta, Giovanni Maria; Galantuomo, Maria Silvana; Fossarello, Maurizio

2014-01-01

The aim was to determine the influence of meibomian gland dysfunction (MGD) and aqueous tear deficiency dry eye (ADDE) on the adhesive properties of the central cornea by means of optical coherence tomography (OCT), and to investigate the relationship between corneal adhesiveness and classical tear tests, as well as the reliability of results, in these lacrimal functional unit disorders. Prospective, case-control study. Twenty-eight patients with MGD and 27 patients with ADDE were studied. A group of 32 healthy subjects of similar age and gender distribution served as a control group. The adhesive properties of the anterior corneal surface were measured by OCT, based on the retention time of adhesion marker above it, in all participants. An excellent (≥5 minutes), borderline (within 3-5 minutes), fair (within 1-3 minutes) and poor (<1 minute) values of corneal adhesiveness were found, respectively, in 0%, 7.1%, 64.3% and 28.6% of MGD, in 0%, 7.4%, 63% and 29.6% of ADDE, and in 31.3%, 65.6%, 3.1% and 0% of healthy patients. The differences in time of corneal adhesiveness between MGD and healthy patients, as well as between ADDE and healthy patients, were found to be statistically significant (p<0.001; p<0.001; respectively). Conversely, no statistical significant differences between MGD and ADDE were found (p = 0.952). Data analysis revealed a statistically significant correlation between corneal adhesiveness and clinical tests of dry eye, as well as an excellent degree of inter-rater reliability and reproducibility for OCT measurements (p<0.001). ADDE and MGD share similar abnormalities on OCT imaging. Decreased adhesive properties of the anterior cornea were identified as a common feature of MGD and ADDE. This simple OCT approach may provide new clues into the mechanism and evaluation of dry eye syndrome.

Management of a neurotrophic deep corneal ulcer with amniotic membrane transplantation in a patient with functional monocular vision

PubMed Central

Röck, Tobias; Bartz-Schmidt, Karl Ulrich; Röck, Daniel

2017-01-01

Abstract Rationale: Amniotic membrane transplantation (AMT) has been performed therapeutically in humans for over 100 years. In recent 2 decades AMTs have been used increasingly and successfully to treat various types of ophthalmic indications. Patient concerns: An 83-year-old man was referred to our eye hospital with a refractory neurotrophic deep corneal ulcer of the left eye. Diagnoses: The best-corrected visual acuity of the left eye was 0.5 (0.3 logMAR) and of the right eye was 0.05 (1.3 logMAR), which was caused by a central retinal vein occlusion 5 years previously. In cases of binocular vision, a large amniotic membrane patch can cover the whole cornea, including the optical axis. However, in cases with functional monocular vision, as in the case reported here, the AMT has to be performed without the involvement of the optical axis to ensure vision for the patient. Otherwise the patient would have a massively restricted view like looking through waxed paper for at least 2–4 weeks until the overlay dissolved. Interventions: For this case, an AMT using a modified sandwich technique was applied without involvement of the optic axis to ensure vision for the patient. This case report illustrates this eye's course of healing over time. Outcomes: A reduction in the inflammation and healing of the corneal ulcer could be seen. In addition, the corneal vascularization decreased. Six months after the AMT, a slit-lamp examination revealed stable findings. The best-corrected visual acuity of the left eye had increased to 0.8 (0.1 logMAR). Lessons: To the best of our knowledge, a case report on the management of a neurotrophic deep corneal ulcer with AMT in a patient with functional monocular vision has never been undertaken before. PMID:29390295

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.

Peripheral Optics with Bifocal Soft and Corneal Reshaping Contact Lenses

PubMed Central

Ticak, Anita; Walline, Jeffrey J.

2012-01-01

Purpose To determine whether bifocal soft contact lenses with a distance center design provide myopic defocus to the peripheral retina similar to corneal reshaping contact lenses. Methods Myopic subjects underwent five cycloplegic autorefraction readings centrally and at 10, 20, and 30 degrees temporally, nasally, superiorly, inferiorly while wearing a Proclear Multifocal “D” contact lens with a +2.00 D add (CooperVision, Fairport, NY) and after wearing a Corneal Refractive Therapy (Paragon Vision Sciences, Mesa, AZ) contact lens for two weeks Results Fourteen subjects completed the study. Nine (64%) were female, and 12 (86%) were Caucasian. The average (± standard deviation) spherical equivalent non-cycloplegic manifest refraction for the right eye was −2.84 ± 1.29 D. The average logMAR best-corrected, binocular high contrast visual acuity was −0.17 ± 0.15 while wearing the bifocal soft contact lens, and −0.09 ± 0.16 following corneal reshaping contact lens wear (ANOVA, p = 0.27). The orthokeratology contact lens yielded a more myopic peripheral optical profile than the soft bifocal contact lens at 20 and 30 degrees eccentricity (except inferior at 20 degrees); the two modalities were similar at 10 degrees eccentricity. Conclusions Our data suggest that the two modalities are dissimilar despite the statistical similarities. The corneal reshaping contact lens shows an increase in relative peripheral myopic refraction, a pattern achieved by other studies, but the bifocal lens does not exhibit such a pattern. The low statistical power of the study could be a reason for a lack of providing statistical difference in other positions of gaze, but the graphical representation of the data shows a marked difference in peripheral optical profile between the two modalities. More sophisticated methods of measuring the peripheral optical profile may be necessary to accurately compare the two modalities and to determine the true optical effect of the bifocal soft contact lens on the peripheral retina. PMID:23222924

Peripheral optics with bifocal soft and corneal reshaping contact lenses.

PubMed

Ticak, Anita; Walline, Jeffrey J

2013-01-01

To determine whether bifocal soft contact lenses with a distance center design provide myopic defocus to the peripheral retina similar to corneal reshaping contact lenses. Myopic subjects underwent five cycloplegic autorefraction readings centrally and at 10, 20, and 30 degrees temporally, nasally, superiorly, and inferiorly while wearing Proclear Multifocal "D" contact lenses with a +2.00-diopter add power (CooperVision, Fairport, NY) and after wearing Corneal Refractive Therapy (Paragon Vision Sciences, Mesa, AZ) contact lenses for 2 weeks. Fourteen subjects completed the study. Nine (64%) were female, and 12 (86%) were white. The average (± SD) spherical equivalent noncycloplegic manifest refraction for the right eye was -2.84 ± 1.29 diopters. The average logMAR best-corrected, binocular, high-contrast visual acuity was -0.17 ± 0.15 while wearing the bifocal soft contact lenses and -0.09 ± 0.16 after corneal reshaping contact lens wear (analysis of variance, p = 0.27). The orthokeratology contact lens yielded a more myopic peripheral optical profile than the soft bifocal contact lens at 20 and 30 degrees eccentricity (except inferior at 20 degrees); the two modalities were similar at 10 degrees eccentricity. Our data suggest that the two modalities are dissimilar despite the statistical similarities. The corneal reshaping contact lens shows an increase in relative peripheral myopic refraction, a pattern achieved by other studies, but the bifocal lens does not exhibit such a pattern. The low statistical power of the study could be a reason for lack of providing statistical difference in other positions of gaze, but the graphical representation of the data shows a marked difference in the peripheral optical profile between the two modalities. More sophisticated methods of measuring the peripheral optical profile may be necessary to accurately compare the two modalities and to determine the true optical effect of the bifocal soft contact lens on the peripheral retina.

Effects of androgen replacement therapy on cornea and tear function in men with idiopathic hypogonadotropic hypogonadism.

PubMed

Gokce, Gokcen; Hurmeric, Volkan; Mumcuoglu, Tarkan; Ozge, Gokhan; Basaran, Yalcin; Unal, Hilmi Umut; Bolu, Erol; Mutlu, Fatih Mehmet

2015-05-01

Idiopathic hypogonadotropic hypogonadism (IHH) is an endocrine disorder defined with the presence of typical clinical signs and symptoms plus laboratory confirmation of serum testosterone (T) levels lower than 300 ng/dl. Androgen replacement therapy (ART) is the first-step treatment of male IHH. To date, no clinical trial, which investigates the changes on corneal structure and tear function, of systemic ART in men have been published. The objective of this study was to investigate the effects of ART on cornea and tear function in patients with IHH. This prospective, interventional study was conducted at the Gulhane Military Medical Academy, Ankara, Turkey, a tertiary referral military hospital. Thirty-four eyes of 17 men with IHH patients were evaluated with Schirmer I test, ultrasound pachymeter, applanation tonometer and confocal microscopy. A Testosterone compound (Sustanon® 250 mg) was administered by intramuscular injection in the course of a 3-week period to induce puberty, and human chorionic gonadotropin (Pregnyl® 5000 IU) was administered twice weekly for 3 months to induce fertility. The patients were re-evaluated at the third month of the treatment. Main Outcome Measures were Schirmer score, central corneal thickness (CCT), intraocular pressure (IOP), endothelial cell density, coefficient of variation and cell shape. Schirmer scores showed similar results after the treatment compared to pre-treatment levels (p = 0.14). There was no statistically significant difference in CCT and IOP compared to baseline data (p = 0.96, p = 0.73, respectively), and no significant differences were found in corneal endothelial cell density, percentage of cell size variability or hexagonality (p = 0.83, p = 0.58, p = 0.64, respectively). This is the first study that investigates the effects of ART on corneal structure and tear function in men. ART seems to have no short-term effects on corneal structure and tear function. Further publications of larger, long-term and controlled studies are needed.

Intraocular pressure values obtained by ocular response analyzer, dynamic contour tonometry, and goldmann tonometry in keratokonic corneas.

PubMed

Bayer, Atilla; Sahin, Afsun; Hürmeriç, Volkan; Ozge, Gökhan

2010-01-01

To determine the agreement between dynamic contour tonometer (DCT), Goldmann applanation tonometer (GAT), and Ocular Response Analyzer (ORA) in keratoconic corneas and to find out the effect of corneal biomechanics on intraocular pressure (IOP) measurements obtained by these devices. IOP was measured with the ORA, DCT, and GAT in random order in 120 eyes of 61 keratoconus patients. Central corneal thickness (CCT) and keratometry were measured after all IOP determinations had been made. The mean IOP measurement by the ORA and DCT was compared with the measurement by the GAT, using Student t test. Bland-Altman analysis was performed to assess the clinical agreement between these methods. The effect of corneal hysteresis (CH), corneal resistance factor (CRF), and CCT on measured IOP was explored by multiple backward stepwise linear regression analysis. The mean±SD patient age was 30.6±11.2 years. The mean±SD IOP measurement obtained with GAT, ORA Goldmann-correlated IOP (IOPg), ORA corneal-compensated IOP (IOPcc), and DCT was 10.96±2.8, 10.23±3.5, 14.65±2.8, and 15.42±2.7 mm Hg, respectively. The mean±SD CCT was 464.08±58.4 microns. The mean difference between IOPcc and GAT (P<0.0001), IOPcc and DCT (P<0.001), GAT and DCT (P<0.0001), IOPg and GAT (P<0.002), and IOPg and DCT (P<0.0001), was highly statistically significant. In multivariable regression analysis, DCT IOP and GAT IOP measurements were significantly associated with CH and CRF (P<0.0001 for both). DCT seemed to be affected by CH and CRF, and the IOP values tended to be higher when compared with GAT. ORA-measured IOPcc was found to be independent of CCT and suitable in comparison to the DCT in keratoconic eyes.

Corneal dystrophies

PubMed Central

Klintworth, Gordon K

2009-01-01

The term corneal dystrophy embraces a heterogenous group of bilateral genetically determined non-inflammatory corneal diseases that are restricted to the cornea. The designation is imprecise but remains in vogue because of its clinical value. Clinically, the corneal dystrophies can be divided into three groups based on the sole or predominant anatomical location of the abnormalities. Some affect primarily the corneal epithelium and its basement membrane or Bowman layer and the superficial corneal stroma (anterior corneal dystrophies), the corneal stroma (stromal corneal dystrophies), or Descemet membrane and the corneal endothelium (posterior corneal dystrophies). Most corneal dystrophies have no systemic manifestations and present with variable shaped corneal opacities in a clear or cloudy cornea and they affect visual acuity to different degrees. Corneal dystrophies may have a simple autosomal dominant, autosomal recessive or X-linked recessive Mendelian mode of inheritance. Different corneal dystrophies are caused by mutations in the CHST6, KRT3, KRT12, PIP5K3, SLC4A11, TACSTD2, TGFBI, and UBIAD1 genes. Knowledge about the responsible genetic mutations responsible for these disorders has led to a better understanding of their basic defect and to molecular tests for their precise diagnosis. Genes for other corneal dystrophies have been mapped to specific chromosomal loci, but have not yet been identified. As clinical manifestations widely vary with the different entities, corneal dystrophies should be suspected when corneal transparency is lost or corneal opacities occur spontaneously, particularly in both corneas, and especially in the presence of a positive family history or in the offspring of consanguineous parents. Main differential diagnoses include various causes of monoclonal gammopathy, lecithin-cholesterol-acyltransferase deficiency, Fabry disease, cystinosis, tyrosine transaminase deficiency, systemic lysosomal storage diseases (mucopolysaccharidoses, lipidoses, mucolipidoses), and several skin diseases (X-linked ichthyosis, keratosis follicularis spinolosa decalvans). The management of the corneal dystrophies varies with the specific disease. Some are treated medically or with methods that excise or ablate the abnormal corneal tissue, such as deep lamellar endothelial keratoplasty (DLEK) and phototherapeutic keratectomy (PTK). Other less debilitating or asymptomatic dystrophies do not warrant treatment. The prognosis varies from minimal effect on the vision to corneal blindness, with marked phenotypic variability. PMID:19236704

Formulation and development of ophthalmic in situ gel for the treatment ocular inflammation and infection using application of quality by design concept.

PubMed

Patel, Nirav; Thakkar, Vaishali; Metalia, Viral; Baldaniya, Lalji; Gandhi, Tejal; Gohel, Mukesh

2016-09-01

The conventional liquid ophthalmic delivery systems exhibit short pre-corneal residence time and the relative impermeability to the cornea which leads to poor ocular bioavailability. The aim of this study was to apply quality by design (QbD) for development of dexamethasone sodium phosphate (DSP) and tobramycin sulfate (TS)-loaded thermoresponsive ophthalmic in situ gel containing Poloxamer 407 and hydroxyl propyl methyl cellulose (HPMC) K4M for prolonging the pre-corneal residence time, ocular bioavability and decreases the frequency of administration of dosage form. The material attributes and the critical quality attributes (CQA) of the in situ gel were identified. Central composite design (CCD) was adopted to optimize the formulation. The ophthalmic in situ forming gels were prepared by cold method. Materials attributes were the amount of Poloxamer 407 and HPMC and CQA identified were Gel strength, mucoadhesive index, gelation temperature and % of drug release of both drug. Optimized batch (F*) containing 16.75% poloxamer 407 and 0.54% HPMC K4M were exhibited all results in acceptable limits. Compared with the marketed formulation, optimized in situ gel showed delayed Tmax, improved Cmax and AUC in rabbit aqueous humor, suggesting the sustained drug release and better corneal penetration and absorption. According to the study, it could be concluded that DSP and TS would be successfully formulated as in situ gelling mucoadhesive system for the treatment of steroid responsive eye infections with the properties of sustained drug release, prolonged ocular retention and improved corneal penetration.

Comparison of 120- and 140-μm SMILE Cap Thickness Results in Eyes With Thick Corneas.

PubMed

Liu, Manli; Zhou, Yugui; Wu, Xianghua; Ye, Tiantian; Liu, Quan

2016-10-01

To evaluate clinical outcomes after small incision lenticule extraction (SMILE) with different cap thicknesses in thick corneas. Forty patients with central corneal thickness of more than 560 μm were recruited in this prospective, randomized, masked, paired-eye study. Patients were randomized to receive SMILE with a 120-μm cap thickness in 1 eye and 140-μm cap thickness in the other. Uncorrected and corrected distance visual acuity (CDVA), contrast sensitivity (CS), higher-order aberrations (HOAs), and morphologic modifications of corneal architecture were measured during the 3-month follow-up period. Postoperative refractive outcomes, visual outcomes, CS, and the changes in HOAs were similar between both groups. The persistence of brightly reflective particles in the corneal interface layer was 1388.6 ± 219.5/mm in eyes with 120-μm cap thickness and 54.7 ± 8.6/mm in eyes with 140-μm cap thickness (P < 0.001). The hyperreflectivity line at the interface layer almost disappeared in all eyes with 140-μm cap thickness, and it still persisted in 43% of the fellow eyes at 3 months postoperatively. The anterior surfaces of lenticules in the 140-μm cap thickness group exhibited more smoothness than in the 120-μm cap thickness group. There was a lower level corneal wound-healing response after SMILE with a 140-μm cap thickness than with a 120-μm cap thickness, although the thickness of cap creation did not affect visual outcomes by 3 months postoperatively.

Clinical evaluation of deep anterior lamellar keratoplasty using glycerol-cryopreserved corneal tissues for refractory herpetic stromal keratitis

PubMed Central

Liu, Xin; Zhou, Qi; Huang, Xinyu; Liu, Zhenxing; Bi, Yanlong

2016-01-01

Abstract The study aimed to evaluate the therapeutic effects of deep anterior lamellar keratoplasty (DALK) using glycerol-cryopreserved corneal tissues (GCCTs) in patients with refractive herpes simplex keratitis (HSK). This article was a retrospective, noncomparative, and interventional case series. Patients with HSK underwent DALK using GCCTs at Shanghai Tongji Hospital from 2012 to 2015. The best spectacle corrected visual acuity, recurrent inflammation, graft status, postoperative central graft thickness, and pre/postoperative complications were detected. The follow-up ranged from 24.4 ± 5.6 months (range: 16–38 months). Overall, the best spectacle corrected visual acuity was increased from HM/10 cm to 0.15 before surgery to 0.41 ± 0.14 (range: 0.1–0.8; P < 0.05) at 12 months postoperatively. Intraoperative microperforation occurred in 4 eyes (14.81%), and rejection episodes were encountered in 3 of 27 eyes (11.1%), and all of the eyes reversed. HSK recurred in 2 eyes (7.41%), 1 eye with repeated recurring HSK, and eventually led to perpetual corneal opacity and the patient refused a retransplantation. The mean entire corneal thickness was 0.519 ± 0.018 mm (range: 0.5–0.56 mm) and the mean graft thickness was 0.405 ± 0.033 mm (range: 0.35–0.47 mm) in the final follow-up. The DALK using GCCTs was proven to be an effective and safe therapy in treating refractory HSK. PMID:27684823

Outcomes of photorefractive keratectomy in patients with atypical topography.

PubMed

Movahedan, Hossein; Namvar, Ehsan; Farvardin, Mohsen

2017-11-01

Photorefractive keratectomy (PRK) is at risk of serious complications such as corneal ectasia, which can reduce corrected distance visual acuity. The rate of complications of PRK is higher in patients with atypical topography. To determine the outcomes of photorefractive keratectomy in patients with atypical topography. This cross-sectional study was done in 2015 in Shiraz in Iran. We included 85 eyes in this study. The samples were selected using a simple random sampling method. All patients were under evaluation for uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction, corneal topography, central corneal thickness using pentacam, slit-lamp microscopy, and detailed fondus evaluation. The postoperative examination was done 1-7 years after surgery. Data were analyzed using IBM SPSS 21.0 version. To analyze the data, descriptive statistics (frequency, percentage, mean, and standard deviation), chi-square, and independent samples t-test were used. We studied 85 eyes. Among the patients, 23 (27.1%) were male and 62 (72.9%) were female. Mean age of the participants was 28.25±5.55 years. Mean postoperative refraction was - 0.37±0.55 diopters. Keratoconus or corneal ectasia was not reported in any patient in this study. There was no statistically significant difference between SI index before and after operation (p=0.736). Mean preoperative refraction was -3.84 ± 1.46 diopters in males and -4.20±1.96 diopters in females; thus there was not statistically significant difference (p = 0.435). PRK is a safe and efficient photorefractive surgery and is associated with low complication rate in patients with atypical topography.

Effects of Repeated Intravitreal Aflibercept Injection on the Corneal Endothelium in Patients With Age-Related Macular Degeneration: Outcomes From the RE-VIEW Study.

PubMed

Lass, Jonathan H; Benetz, Beth Ann; Menegay, Harry J; Tsipis, Constantinos P; Cook, Jane Caty; Boyer, David S; Singer, Michael; Erickson, Kristine; Saroj, Namrata; Vitti, Robert; Chu, Karen W; Moini, Hadi; Soo, Yuhwen; Cheng, Yenchieh

2018-05-01

The effects of repeated intravitreal aflibercept injection (IAI) on the corneal endothelium were studied in patients with unilateral neovascular age-related macular degeneration. RE-VIEW was a phase 4, open-label, single-arm, multicenter study. Patients received IAI every 8 weeks after 3 monthly doses. Slit-lamp biomicroscopy was performed at all study visits. The central corneal endothelial health was evaluated by specular microscopy in the treated versus untreated fellow eyes at baseline and weeks 24 and 52. No slit-lamp abnormalities were noted in 154 enrolled patients (eyes). Baseline versus 52-week mean (±SD) endothelial morphometric values (n = 118) for the treated versus untreated fellow eyes were respectively as follows: endothelial cell density was 2410 ± 364 versus 2388 ± 384 cells/mm at baseline and remained unchanged at 2401 ± 353 versus 2376 ± 364 cells/mm at 52 weeks (P = 0.87); the coefficient of variation was 33.5 ± 4.4% versus 34.0 ± 5.0% at baseline and remained unchanged at 34.2 ± 4.7% versus 34.1 ± 4.9% at 52 weeks (P = 0.18); the percentage of hexagonal cells was 59.5 ± 5.8% versus 59.6 ± 6.4% at baseline and remained unchanged at 59.5 ± 6.0% versus 59.5 ± 5.8% at 52 weeks (P = 0.96). Repeated IAI for 52 weeks had no apparent corneal endothelial toxicity noted on specular microscopy in patients treated for neovascular age-related macular degeneration.

Corneal endothelial morphology and function after torsional and longitudinal ultrasound mode phacoemulsification

PubMed Central

Módis, László Jr.; Szalai, Eszter; Flaskó, Zsuzsa; Németh, Gábor

2016-01-01

Purpose. To study the endothelial cell morphology and corneal thickness changes after phacoemulsification by using the OZil torsional and longitudinal ultrasound techniques (Infiniti Vision System, Alcon Laboratories). Setting. Department of Ophthalmology, Clinical Center, University of Debrecen, Debrecen, Hungary. Methods. 52 patients with cataract were randomly assigned to longitudinal ultrasound and torsional mode group. All surgeries were performed through a 2.2 mm clear corneal incision, the method employed being divide and conquer. The endothelial morphometry such as cell density (ECD), mean cell area, coefficient of variation of cell area, and central corneal thickness were examined with specular microscopy (EM-1000, Tomey) preoperatively and 4, 8 weeks postoperatively. Results. ECD values decreased significantly in both surgical groups (P < .001, repeated- mesures ANOVA), the postoperative endothelial cell loss was higher in the longitudinal ultrasound mode group (3.5% and 6.5%, at 4 and 8 weeks after surgery) than in the torsional group (3.3% and 5.5%, at 4 and 8 weeks after surgery), the difference not being significant between the two groups (P = .164 and P = .479, at 4 and 8 weeks after surgery, Mann-Whitney test). There was no statistically significant difference in any of the assessed parameters between the two surgical groups (P > .05). No significant correlation was found between the endothelial cell loss and the nucleus density. Conclusions. Both phacoemulsification techniques were safe and effective. The torsional handpiece performs oscillatory movements and delivers less energy into the eye than the longitudinal ultrasound technique, therefore providing more favorable energy and thermal safety profile. PMID:29450332

Age-Related Changes in Corneal Astigmatism.

PubMed

Shao, Xu; Zhou, Kai-Jing; Pan, An-Peng; Cheng, Xue-Ying; Cai, He-Xie; Huang, Jin-Hai; Yu, A-Yong

2017-10-01

To analyze the changes in corneal astigmatism as a function of age and develop a novel model to estimate corneal astigmatic change according to age. This was a cross-sectional study of right eyes of 3,769 individuals. Total corneal astigmatism, keratometric astigmatism, anterior corneal astigmatism, and posterior corneal astigmatism were measured by a Scheimpflug tomographer. Smoothing fitting curves of polar values of corneal astigmatism as a function of age were drawn and average changes in corneal astigmatism at different ages were calculated. Two turning points of age on total corneal astigmatism were 36 and 69 years. The average change of total corneal astigmatism toward against-the-rule astigmatism was 0.13 diopters (D)/10 years from 18 to 35 years, 0.45 D/10 years from 36 to 68 years, and decreased after 69 years, mainly caused by anterior corneal astigmatism. The mean magnitude of posterior corneal astigmatism was -0.33 D and exceeded 0.50 D in 14.27% of eyes. The vectorial difference between total corneal astigmatism and keratometric astigmatism was correlated with posterior corneal astigmatism, polar value of anterior corneal astigmatism, age, and corneal higher order aberrations (r = 0.636; standard partial regression coefficients were 0.479, -0.466, 0.282, and 0.196, respectively; all P < .001). Based on the non-linear model to estimate corneal astigmatic change with age, a formula was developed to calculate recommended correction of astigmatism according to age and astigmatic type. The rate of change of total corneal astigmatism showed a non-linear trend toward against-the-rule astigmatism, which was low at young and old age, high at middle age, and should be taken into account when performing surgery to correct astigmatism. [J Refract Surg. 2017;33(10):696-703.]. Copyright 2017, SLACK Incorporated.

Prevalence and causes of blindness and visual impairment among school children in south-western Nigeria.

PubMed

Ajaiyeoba, A I; Isawumi, M A; Adeoye, A O; Oluleye, T S

2005-01-01

The aim of the study was to assess the prevalence and identify the causes of blindness and visual impairment in school children of Ilesa-East Local Government Area of Osun State, Nigeria. A total of 1144 school children in primary and secondary schools were selected using a 2-stage random sampling method and examined to determine the prevalence and causes of blindness and visual impairment. A total of 17 (1.48%) children were blind or visually impaired. These comprised of 11 (0.96%) children who were visually impaired and 4 (0.3%) who were severely visually impaired. Only 2 (0.15%) school children were blind. The causes of visual impairment were refractive error 10 (0.87%) and immature cataract 1 (0.08%), causes of severe visual impairment included corneal opacities 2 (0.2%), amblyopia leading to squint 1 (0.08%) and 1 cataract 1 (0.08%). The causes of blindness in school children were corneal scars presumed to be due to vitamin A deficiency 1 (0.08%) and keratoconus 1 (0.08%). Causes of blindness and visual impairment in children attending regular schools in Nigeria were treatable. Prevention, early recognition and prompt treatment of these diseases by regular screening of school children would definitely reduce unnecessary visual handicap in Nigerian school children so that they can attain their full potential in the course of their education. Also, information from this study is relevant for the purpose of planning eye care programmes for the prevention of blindness in Nigerian school children. This will go a long way in the prevention of unnecessary blindness and visual impairment in school children.

Spontaneous Corneal Hydrops in a Patient with a Corneal Ulcer

PubMed Central

Batawi, Hatim; Kothari, Nikisha; Camp, Andrew; Bernhard, Luis; Karp, Carol L.; Galor, Anat

2016-01-01

Purpose We report the case of a 77-year-old man with no history of keratoconus or other ectatic disorders who presented with corneal hydrops in the setting of a corneal ulcer. The risk factors, pathogenesis and treatment options of corneal hydrops are discussed. Method This is an observational case report study. Results A 77-year-old man presented with a 1-day history of severe pain, redness, mucous discharge and photophobia in the right eye. A slit-lamp examination of the right eye showed an area of focal corneal edema and protrusion. Within the area of edema and protrusion, there was an infiltrate with an overlying epithelial defect consistent with an infectious corneal ulcer. The Seidel test showed no leakage, so a clinical diagnosis of corneal hydrops associated with nonperforated corneal ulcer was made. With appropriate antibiotic treatment, the corneal ulcer and hydrops both resolved over a 1-month period. Conclusion Corneal hydrops can occur in the setting of corneal infections. PMID:26889160

Spontaneous Corneal Hydrops in a Patient with a Corneal Ulcer.

PubMed

Batawi, Hatim; Kothari, Nikisha; Camp, Andrew; Bernhard, Luis; Karp, Carol L; Galor, Anat

2016-01-01

We report the case of a 77-year-old man with no history of keratoconus or other ectatic disorders who presented with corneal hydrops in the setting of a corneal ulcer. The risk factors, pathogenesis and treatment options of corneal hydrops are discussed. This is an observational case report study. A 77-year-old man presented with a 1-day history of severe pain, redness, mucous discharge and photophobia in the right eye. A slit-lamp examination of the right eye showed an area of focal corneal edema and protrusion. Within the area of edema and protrusion, there was an infiltrate with an overlying epithelial defect consistent with an infectious corneal ulcer. The Seidel test showed no leakage, so a clinical diagnosis of corneal hydrops associated with nonperforated corneal ulcer was made. With appropriate antibiotic treatment, the corneal ulcer and hydrops both resolved over a 1-month period. Corneal hydrops can occur in the setting of corneal infections.

Curvularia keratitis.

PubMed Central

Wilhelmus, K R; Jones, D B

2001-01-01

PURPOSE: To determine the risk factors and clinical signs of Curvularia keratitis and to evaluate the management and outcome of this corneal phaeohyphomycosis. METHODS: We reviewed clinical and laboratory records from 1970 to 1999 to identify patients treated at our institution for culture-proven Curvularia keratitis. Descriptive statistics and regression models were used to identify variables associated with the length of antifungal therapy and with visual outcome. In vitro susceptibilities were compared to the clinical results obtained with topical natamycin. RESULTS: During the 30-year period, our laboratory isolated and identified Curvularia from 43 patients with keratitis, of whom 32 individuals were treated and followed up at our institute and whose data were analyzed. Trauma, usually with plants or dirt, was the risk factor in one half; and 69% occurred during the hot, humid summer months along the US Gulf Coast. Presenting signs varied from superficial, feathery infiltrates of the central cornea to suppurative ulceration of the peripheral cornea. A hypopyon was unusual, occurring in only 4 (12%) of the eyes but indicated a significantly (P = .01) increased risk of subsequent complications. The sensitivity of stained smears of corneal scrapings was 78%. Curvularia could be detected by a panfungal polymerase chain reaction. Fungi were detected on blood or chocolate agar at or before the time that growth occurred on Sabouraud agar or in brain-heart infusion in 83% of cases, although colonies appeared only on the fungal media from the remaining 4 sets of specimens. Curvularia was the third most prevalent filamentous fungus among our corneal isolates and the most common dematiaceous mold. Corneal isolates included C senegalensis, C lunata, C pallescens, and C prasadii. All tested isolates were inhibited by 4 micrograms/mL or less of natamycin. Topical natamycin was used for a median duration of 1 month, but a delay in diagnosis beyond 1 week doubled the average length of topical antifungal treatment (P = .005). Visual acuity improved to 20/40 or better in 25 (78%) of the eyes. CONCLUSIONS: Curvularia keratitis typically presented as superficial feathery infiltration, rarely with visible pigmentation, that gradually became focally suppurative. Smears of corneal scrapings often disclosed hyphae, and culture media showed dematiaceous fungal growth within 1 week. Natamycin had excellent in vitro activity and led to clinical resolution with good vision in most patients with corneal curvulariosis. Complications requiring surgery were not common but included exophytic inflammatory fungal sequestration, treated by superficial lamellar keratectomy, and corneal perforation, managed by penetrating keratoplasty. PMID:11797300

The corneal fibrosis response to epithelial-stromal injury

PubMed Central

Torricelli, Andre A. M.; Santhanam, Abirami; Wu, Jiahui; Singh, Vivek; Wilson, Steven E.

2014-01-01

The corneal wound healing response, including the development of stromal opacity in some eyes, is a process that often leads to scarring that occurs after injury, surgery or infection to the cornea. Immediately after epithelial and stromal injury, a complex sequence of processes contributes to wound repair and regeneration of normal corneal structure and function. In some corneas, however, often depending on the type and extent of injury, the response may also lead to the development of mature vimentin+ α-smooth muscle actin+ desmin+ myofibroblasts. Myofibroblasts are specialized fibroblastic cells generated in the cornea from keratocyte-derived or bone marrow-derived precursor cells. The disorganized extracellular matrix components secreted by myofibroblasts, in addition to decreased expression of corneal crystallins in these cells, are central biological processes that result in corneal stromal fibrosis associated with opacity or “haze”. Several factors are associated with myofibroblast generation and haze development after PRK surgery in rabbits, a reproducible model of scarring, including the amount of tissue ablated, which may relate to the extent of keratocyte apoptosis in the early response to injury, irregularity of stromal surface after surgery, and changes on corneal stromal proteoglycans, but normal regeneration of the epithelial basement membrane (EBM) appears to be a critical factor determining whether a cornea heals with relative transparency or vision-limiting stromal opacity. Structural and functional abnormalities of the regenerated EBM facilitate prolonged entry of epithelium-derived growth factors such as transforming growth factor β (TGF-β) and platelet-derived growth factor (PDGF) into the stroma that both drive development of mature myofibroblasts from precursor cells and lead to persistence of the cells in the anterior stroma. A major discovery that has contributed to our understanding of haze development is that keratocytes and corneal fibroblasts, but not myofibroblasts, produce large amounts of critical EBM components, such as nidogen-1, nidogen-2 and perlecan, that are essential for complete regeneration of a normal EBM once laminin secreted by epithelial cells self-polymerizes into a nascent EBM. Mature myofibroblasts that become established in the anterior stroma are a barrier to keratocyte contributions to the nascent EBM. These myofibroblasts, and the opacity they produce, often persist for months or years after the injury. Transparency is subsequently restored when the EBM is completely regenerated, myofibroblasts are deprived of TGFβ and undergo apoptosis, and the keratocytes re-occupy the anterior stroma and reabsorb disordered extracellular matrix. The aim of this review is to highlight factors involved in the generation of stromal haze and its subsequent removal. PMID:26675407

[Design and Realization of Personalized Corneal Analysis Software Based on Corneal Topography System].

PubMed

Huang, Xueping; Xie, Zhonghao; Cen, Qin; Zheng, Suilian

2016-08-01

As the most important refraction part in the optical system,cornea possesses characteristics which are important parameters in ophthalmology clinical surgery.During the measurement of the cornea in our study,we acquired the corneal data of Orbscan Ⅱ corneal topographer in real time using the Hook technology under Windows,and then took the data into the corneal analysis software.We then further analyzed and calculated the data to obtain individual Q-value of overall corneal 360semi-meridian.The corneal analysis software took Visual C++ 6.0as development environment,used OpenGL graphics technology to draw three-dimensional individual corneal morphological map and the distribution curve of the Q-value,and achieved real-time corneal data query.It could be concluded that the analysis would further extend the function of the corneal topography system,and provide a solid foundation for the further study of automatic screening of corneal diseases.

Recurrent Corneal Erosions in Corneal Dystrophies: a Review of the Pathogenesis, Differential Diagnosis, and Therapy.

PubMed

Omari, Amro A; Mian, Shahzad I

2018-06-01

Recurrent corneal erosions in corneal dystrophies are visually significant and bothersome to patients. The goal of this article is to review the pathogenesis, differential diagnosis, and management of recurrent corneal erosions in corneal dystrophies. Forty-eight articles and 1 textbook recently published on corneal erosions in corneal dystrophies were reviewed. The findings on the pathogenesis and clinical characteristics of erosions in each dystrophy were summarized. Any contradicting opinions for which the literature was unclear were either omitted or recorded as lacking strong evidence. The epithelial-stromal complex plays an important role in the pathogenesis of erosions in corneal dystrophies. The clinical features of each corneal dystrophy guide their diagnosis and management. A better understanding of the pathogenesis and clinical features of erosions in corneal dystrophies can lead to better clinical outcomes. Georg Thieme Verlag KG Stuttgart · New York.

Factors influencing flap and INTACS decentration after femtosecond laser application in normal and keratoconic eyes.

PubMed

Ertan, Aylin; Karacal, Humeyra

2008-10-01

To compare accuracy of LASIK flap and INTACS centration following femtosecond laser application in normal and keratoconic eyes. This is a retrospective case series comprising 133 eyes of 128 patients referred for refractive surgery. All eyes were divided into two groups according to preoperative diagnosis: group 1 (LASIK group) comprised 74 normal eyes of 72 patients undergoing LASIK with a femtosecond laser (IntraLase), and group 2 (INTACS group) consisted of 59 eyes of 39 patients with keratoconus for whom INTACS were implanted using a femtosecond laser (IntraLase). Decentration of the LASIK flap and INTACS was analyzed using Pentacam. Temporal decentration was 612.56 +/- 384.24 microm (range: 30 to 2120 microm) in the LASIK group and 788.33 +/- 500.34 microm (range: 30 to 2450 microm) in the INTACS group. A statistically significant difference was noted between the groups in terms of decentration (P < .05). Regression analysis showed that the amount of decentration of the LASIK flap and INTACS correlated with the central corneal thickness in the LASIK group and preoperative sphere and cylinder in the INTACS group, respectively. Decentration with the IntraLase occurred in most cases, especially in keratoconic eyes. The applanation performed for centralization during IntraLase application may flatten and shift the pupil center, and thus cause decentralization of the LASIK flap and INTACS. Central corneal thickness in the LASIK group and preoperative sphere and cylinder in the INTACS group proved to be statistically significant parameters associated with decentration.

Influence of corneal hydration on optical coherence elastography

NASA Astrophysics Data System (ADS)

Twa, Michael D.; Vantipalli, Srilatha; Singh, Manmohan; Li, Jiasong; Larin, Kirill V.

2016-03-01

Corneal biomechanical properties are influenced by several factors, including intraocular pressure, corneal thickness, and viscoelastic responses. Corneal thickness is directly proportional to tissue hydration and can influence corneal stiffness, but there is no consensus on the magnitude or direction of this effect. We evaluated the influence of corneal hydration on dynamic surface deformation responses using optical coherence elastography (OCE). Fresh rabbit eyes (n=10) were prepared by removing the corneal epithelium and dropping with 0.9% saline every 5 minutes for 1 hour, followed by 20% dextran solution every 5 minutes for one hour. Corneal thickness was determined from structural OCT imaging and OCE measurements were performed at baseline and every 20 minutes thereafter. Micron-scale deformations were induced at the apex of the corneal tissue using a spatially-focused (150μm) short-duration (<1ms) air-pulse delivery system. These dynamic tissue responses were measured non-invasively with a phase-stabilized swept source OCT system. The tissue surface deformation response (Relaxation Rate: RR) was quantified as the time constant, over which stimulated tissue recovered from the maximum deformation amplitude. Elastic wave group velocity (GV) was also quantified and correlated with change in corneal thickness due to hydration process. Corneal thickness rapidly increased and remained constant following epithelium removal and changed little thereafter. Likewise, corneal stiffness changed little over the first hour and then decreased sharply after Dextran application (thickness: -46% [-315/682 μm] RR: - 24% [-0.7/2.88 ms-1]; GV: -19% [-0.6/3.2 m/s]). Corneal thickness and corneal stiffness (RR) were well correlated (R2 = .66). Corneal biomechanical properties are highly correlated with tissue hydration over a wide range of corneal thickness and these changes in corneal stiffness are quantifiable using OCE.

Construction of a Corneal Stromal Equivalent with SMILE-Derived Lenticules and Fibrin Glue

PubMed Central

Yin, Houfa; Qiu, Peijin; Wu, Fang; Zhang, Wei; Teng, Wenqi; Qin, Zhenwei; Li, Chao; Zhou, Jiaojie; Fang, Zhi; Tang, Qiaomei; Fu, Qiuli; Ma, Jian; Yang, Yabo

2016-01-01

The scarcity of corneal tissue to treat deep corneal defects and corneal perforations remains a challenge. Currently, small incision lenticule extraction (SMILE)-derived lenticules appear to be a promising alternative for the treatment of these conditions. However, the thickness and toughness of a single piece of lenticule are limited. To overcome these limitations, we constructed a corneal stromal equivalent with SMILE-derived lenticules and fibrin glue. In vitro cell culture revealed that the corneal stromal equivalent could provide a suitable scaffold for the survival and proliferation of corneal epithelial cells, which formed a continuous pluristratified epithelium with the expression of characteristic markers. Finally, anterior lamellar keratoplasty in rabbits demonstrated that the corneal stromal equivalent with decellularized lenticules and fibrin glue could repair the anterior region of the stroma, leading to re-epithelialization and recovery of both transparency and ultrastructural organization. Corneal neovascularization, graft degradation, and corneal rejection were not observed within 3 months. Taken together, the corneal stromal equivalent with SMILE-derived lenticules and fibrin glue appears to be a safe and effective alternative for the repair of damage to the anterior cornea, which may provide new avenues in the treatment of deep corneal defects or corneal perforations. PMID:27651001

Construction of a Corneal Stromal Equivalent with SMILE-Derived Lenticules and Fibrin Glue.

PubMed

Yin, Houfa; Qiu, Peijin; Wu, Fang; Zhang, Wei; Teng, Wenqi; Qin, Zhenwei; Li, Chao; Zhou, Jiaojie; Fang, Zhi; Tang, Qiaomei; Fu, Qiuli; Ma, Jian; Yang, Yabo

2016-09-21

The scarcity of corneal tissue to treat deep corneal defects and corneal perforations remains a challenge. Currently, small incision lenticule extraction (SMILE)-derived lenticules appear to be a promising alternative for the treatment of these conditions. However, the thickness and toughness of a single piece of lenticule are limited. To overcome these limitations, we constructed a corneal stromal equivalent with SMILE-derived lenticules and fibrin glue. In vitro cell culture revealed that the corneal stromal equivalent could provide a suitable scaffold for the survival and proliferation of corneal epithelial cells, which formed a continuous pluristratified epithelium with the expression of characteristic markers. Finally, anterior lamellar keratoplasty in rabbits demonstrated that the corneal stromal equivalent with decellularized lenticules and fibrin glue could repair the anterior region of the stroma, leading to re-epithelialization and recovery of both transparency and ultrastructural organization. Corneal neovascularization, graft degradation, and corneal rejection were not observed within 3 months. Taken together, the corneal stromal equivalent with SMILE-derived lenticules and fibrin glue appears to be a safe and effective alternative for the repair of damage to the anterior cornea, which may provide new avenues in the treatment of deep corneal defects or corneal perforations.

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.

Component corneal surgery: An update

PubMed Central

Maharana, Prafulla K.; Sahay, Pranita; Singhal, Deepali; Garg, Itika; Titiyal, Jeewan S.; Sharma, Namrata

2017-01-01

Several decades ago, penetrating keratoplasty was a challenge to corneal surgeons. Constant effort by the corneal surgeon to improve the outcomes as well as utilization of the available resources has led to a revolutionary change in the field of keratoplasty. All these efforts have led to the evolution of techniques that allow a corneal surgeon to disease-specific transplant of individual layers of corneal “so-called component corneal surgery” depending on the layer of cornea affected. This has led to an improvement in corneal graft survival as well as a better utilization of corneal tissues. This article reviews the currently available literature on component corneal surgeries and provides an update on the available techniques. PMID:28820150

The usefulness of CorvisST Tonometry and the Ocular Response Analyzer to assess the progression of glaucoma

NASA Astrophysics Data System (ADS)

Matsuura, Masato; Hirasawa, Kazunori; Murata, Hiroshi; Nakakura, Shunsuke; Kiuchi, Yoshiaki; Asaoka, Ryo

2017-01-01

Corneal Visualization Scheimpflug Technology (CST) and Ocular Response Analyzer (ORA) measurements were carried out in 105 eyes of 69 patients with primary open-angle glaucoma. All patients had axial length (AL), central corneal thickness (CCT), intraocular pressure (IOP) with Goldmann applanation tonometry (GAT) and eight visual fields (VF)s with the Humphrey Field Analyzer. VF progression was summarized using a time trend analysis of mean total deviation (mTD) and the association between mTD progression rate and a number of ocular parameters (including CST and ORA measurements) was assessed using mixed linear regression analysis. The optimal model of VF progression selected based on the corrected Akaike Information Criteria (AICc) included ORA’s corneal hysteresis (CH) parameter as well as a number of CST measurements: mTD progression rate = 1.2-0.070 * mean GAT + 0.090 * CH-1.5 * highest concavity deformation amplitude with CST + 9.4 * A1 deformation amplitude with CST-0.05 * A2 length with CST (AICc = 125.8). Eyes with corneas that experience deep indentation at the maximum deformation, shallow indentation at the first applanation and wide indentation at the second applanation in the CST measurement are more likely to experience faster rates of VF progression.

The Prospective Health Assessment of Cataract Patients’ Ocular Surface (PHACO) study: the effect of dry eye

PubMed Central

Trattler, William B; Majmudar, Parag A; Donnenfeld, Eric D; McDonald, Marguerite B; Stonecipher, Karl G; Goldberg, Damien F

2017-01-01

Purpose To determine the incidence and severity of dry eye as determined by the International Task Force (ITF) scale in patients being screened for cataract surgery. Patients and methods This was a prospective, multi-center, observational study of 136 patients, at least 55 years of age, who were scheduled to undergo cataract surgery. The primary outcome measure was the incidence of dry eye as evaluated by grade on the ITF scale and secondary outcome measures include tear break-up time (TBUT), ocular surface disease index score, corneal staining with fluorescein, conjunctival staining with lissamine green, and a patient questionnaire to evaluate symptoms of dry eye. Results Mean patient age was 70.7 years. A total of 73.5% of patients were Caucasian and 50% were female. Almost 60% had never complained of a foreign body sensation; only 13% complained of a foreign body sensation half or most of the time. The majority of patients (62.9%) had a TBUT ≤5 seconds, 77% of eyes had positive corneal staining and 50% of the eyes had positive central corneal staining. Eighteen percent had Schirmer’s score with anesthesia ≤5 mm. Conclusion The incidence of dry eye in patients scheduled to undergo cataract surgery in a real-world setting is higher than anticipated. PMID:28848324

Effect of laser peripheral iridotomy using argon and neodymium-YAG lasers on corneal endothelial cell density: 7-year longitudinal evaluation.

PubMed

Ono, Takashi; Iida, Masaharu; Sakisaka, Toshihiro; Minami, Keiichiro; Miyata, Kazunori

2018-03-01

To evaluate the changes in corneal endothelial cell density (ECD) over a 7-year period after laser peripheral iridotomy (LPI) using argon and neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. Retrospective case series. Eyes that underwent prophylactic LPI using argon and Nd:YAG lasers were followed up for 7 years. Central corneal endothelial cells were observed by use of noncontact specular microscopy preoperatively and at 1 and 7 years postoperatively. Changes in ECD and the associations between preoperative ECD and the total energy of the Nd:YAG laser were evaluated. Fifty-one eyes of 51 patients were followed up for 7 years. The ECD significantly decreased after LPI (P < 0.049), and the reduction rate at 1 year after the surgery (1.69 ± 4.80%, 95% CI: 0.34%-3.04%) was significantly higher than the annual reduction rates after 1 year (0.17 ± 0.85%/y, P = 0.036, 95% CI: -0.07% to 0.41%). No association was found between the preoperative ECD and the total laser energy. Long-term evaluation indicated that the reduction in ECD after argon-Nd:YAG laser LPI was present but small during the initial year and was negligible after 1 year.

Posterior Corneal Characteristics of Cataract Patients with High Myopia

PubMed Central

Jing, Qinghe; Tang, Yating; Qian, Dongjin; Lu, Yi; Jiang, Yongxiang

2016-01-01

Purpose To evaluate the characteristics of the posterior corneal surface in patients with high myopia before cataract surgery. Methods We performed a cross-sectional study at the Eye and ENT Hospital of Fudan University, Shanghai, China. Corneal astigmatism and axial length were measured with a rotating Scheimpflug camera (Pentacam) and partial coherence interferometry (IOLMaster) in a high-myopia study group of 167 eyes (axial length ≥ 26 mm) and a control group of 150 eyes (axial length > 20 mm and < 25 mm). Results Total corneal astigmatism and anterior corneal astigmatism values were higher in the high-myopia group than in the control group. There was no significant difference in posterior corneal astigmatism between the high-myopia study group and the control group. In the study group, the mean posterior corneal astigmatism (range 0 – −0.9 diopters) was –0.29 diopters (D) ± 0.17 standard deviations (SD). The steep corneal meridian was aligned vertically (60°–120°) in 87.43% of eyes for the posterior corneal surface, and did not change with increasing age. There was a significant correlation (r = 0.235, p = 0.002) between posterior corneal astigmatism and anterior corneal astigmatism, especially when the anterior corneal surface showed with-the-rule (WTR) astigmatism (r = 0.452, p = 0.000). There was a weak negative correlation between posterior corneal astigmatism and age (r = –0.15, p = 0.053) in the high-myopia group. Compared with total corneal astigmatism values, the anterior corneal measurements alone overestimated WTR astigmatism by a mean of 0.27 ± 0.18 D in 68.75% of eyes, underestimated against-the-rule (ATR) astigmatism by a mean of 0.41 ± 0.28 D in 88.89% of eyes, and underestimated oblique astigmatism by a mean of 0.24 ± 0.13 D in 63.64% of eyes. Conclusions Posterior corneal astigmatism decreased with age and remained as ATR astigmatism in most cases of high myopia. There was a significant correlation between posterior corneal astigmatism and anterior corneal astigmatism when anterior corneal astigmatism was WTR. If posterior corneal astigmatism is not accounted for when selecting toric intraocular lenses for high-myopia patients, the use of anterior corneal astigmatism measurements alone will lead to overestimation of WTR astigmatism and underestimation of ATR and oblique astigmatism. PMID:27603713

Posterior Corneal Characteristics of Cataract Patients with High Myopia.

PubMed

Jing, Qinghe; Tang, Yating; Qian, Dongjin; Lu, Yi; Jiang, Yongxiang

2016-01-01

To evaluate the characteristics of the posterior corneal surface in patients with high myopia before cataract surgery. We performed a cross-sectional study at the Eye and ENT Hospital of Fudan University, Shanghai, China. Corneal astigmatism and axial length were measured with a rotating Scheimpflug camera (Pentacam) and partial coherence interferometry (IOLMaster) in a high-myopia study group of 167 eyes (axial length ≥ 26 mm) and a control group of 150 eyes (axial length > 20 mm and < 25 mm). Total corneal astigmatism and anterior corneal astigmatism values were higher in the high-myopia group than in the control group. There was no significant difference in posterior corneal astigmatism between the high-myopia study group and the control group. In the study group, the mean posterior corneal astigmatism (range 0 - -0.9 diopters) was -0.29 diopters (D) ± 0.17 standard deviations (SD). The steep corneal meridian was aligned vertically (60°-120°) in 87.43% of eyes for the posterior corneal surface, and did not change with increasing age. There was a significant correlation (r = 0.235, p = 0.002) between posterior corneal astigmatism and anterior corneal astigmatism, especially when the anterior corneal surface showed with-the-rule (WTR) astigmatism (r = 0.452, p = 0.000). There was a weak negative correlation between posterior corneal astigmatism and age (r = -0.15, p = 0.053) in the high-myopia group. Compared with total corneal astigmatism values, the anterior corneal measurements alone overestimated WTR astigmatism by a mean of 0.27 ± 0.18 D in 68.75% of eyes, underestimated against-the-rule (ATR) astigmatism by a mean of 0.41 ± 0.28 D in 88.89% of eyes, and underestimated oblique astigmatism by a mean of 0.24 ± 0.13 D in 63.64% of eyes. Posterior corneal astigmatism decreased with age and remained as ATR astigmatism in most cases of high myopia. There was a significant correlation between posterior corneal astigmatism and anterior corneal astigmatism when anterior corneal astigmatism was WTR. If posterior corneal astigmatism is not accounted for when selecting toric intraocular lenses for high-myopia patients, the use of anterior corneal astigmatism measurements alone will lead to overestimation of WTR astigmatism and underestimation of ATR and oblique astigmatism.

Assessment of corneal properties based on statistical modeling of OCT speckle.

PubMed

Jesus, Danilo A; Iskander, D Robert

2017-01-01

A new approach to assess the properties of the corneal micro-structure in vivo based on the statistical modeling of speckle obtained from Optical Coherence Tomography (OCT) is presented. A number of statistical models were proposed to fit the corneal speckle data obtained from OCT raw image. Short-term changes in corneal properties were studied by inducing corneal swelling whereas age-related changes were observed analyzing data of sixty-five subjects aged between twenty-four and seventy-three years. Generalized Gamma distribution has shown to be the best model, in terms of the Akaike's Information Criterion, to fit the OCT corneal speckle. Its parameters have shown statistically significant differences (Kruskal-Wallis, p < 0.001) for short and age-related corneal changes. In addition, it was observed that age-related changes influence the corneal biomechanical behaviour when corneal swelling is induced. This study shows that Generalized Gamma distribution can be utilized to modeling corneal speckle in OCT in vivo providing complementary quantified information where micro-structure of corneal tissue is of essence.

Measurement of Posterior Corneal Astigmatism by the IOLMaster 700.

PubMed

LaHood, Benjamin R; Goggin, Michael

2018-05-01

To provide the first description of posterior corneal astigmatism as measured by the IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany) and assess how its characteristics compare to previous measurements from other devices. A total of 1,098 routine IOLMaster 700 biometric measurements were analyzed to provide magnitudes and orientation of steep and flat axes of anterior and posterior corneal astigmatism. Subgroup analysis was conducted to assess correlation of posterior corneal astigmatism characteristics to anterior corneal astigmatism and describe the distribution of posterior corneal astigmatism with age. Mean posterior corneal astigmatism was 0.24 ± 0.15 diopters (D). The steep axis of posterior corneal astigmatism was vertically oriented in 73.32% of measurements. Correlation between the magnitude of anterior and posterior corneal astigmatism was greatest when the steep axis of the anterior corneal astigmatism was oriented vertically (r = 0.68, P < .0001). Vertical orientation of the steep axis of anterior corneal astigmatism became less common as age increased, whereas for posterior corneal astigmatism it remained by far the most common orientation. This first description of posterior corneal astigmatism measurement by the IOLMaster 700 found the average magnitude of posterior corneal astigmatism and proportion of vertical orientation of steep axis was lower than previous estimates. The IOLMaster 700 appears capable of providing enhanced biometric measurement for individualized surgical planning. [J Refract Surg. 2018;34(5):331-336.]. Copyright 2018, SLACK Incorporated.

Topographical analysis of corneal astigmatism in patients with tilted-disc syndrome.

PubMed

Bozkurt, Banu; Irkec, Murat; Gedik, Sansal; Orhan, Mehmet; Erdener, Uğur

2002-07-01

To evaluate the corneal topography in patients with tilted-disc syndrome to determine the relationship between optic disc dysversion and corneal astigmatism and the pattern of astigmatism in these patients. The study included 23 eyes of the 13 tilted-disc syndrome patients with spheric refractive errors ranging between +1.00 D and -9.00 D (mean -4.00 +/- 3.4 D) and astigmatic errors ranging between -0.50 and -4.50 D (mean -1.95 +/- 0.93 D). Corneal topography was performed by computer-assisted videokeratoscope topographic modelling system 2 (TMS-2) and incidence of corneal astigmatism, corneal topographic patterns, and mean values of the topographic indices were determined. Corneal topographic analysis showed corneal astigmatism in 22 out of 23 patients with tilted discs. Corneal astigmatism was symmetric bow tie pattern in 10 eyes (45.45%), asymmetric bow tie pattern in 11 eyes (50%) and irregular in 1 eye (4.5%). Among the patients with bow tie pattern group (21 eyes), 14 eyes had with-the-rule astigmatism, 1 eye had against-the-rule astigmatism, and 6 eyes had oblique astigmatism. In 18 eyes, astigmatism was corneal, whereas combined corneal and lenticular in 4 eyes and lenticular in 1 eye. In the majority of tilted-disc cases, ocular astigmatism is mainly corneal. Morphogenetic factors in the development of the tilted disc might possibly influence the corneal development in such a way to result in corneal astigmatism.

Toric Intraocular Lenses in the Correction of Astigmatism During Cataract Surgery: A Systematic Review and Meta-analysis.

PubMed

Kessel, Line; Andresen, Jens; Tendal, Britta; Erngaard, Ditte; Flesner, Per; Hjortdal, Jesper

2016-02-01

We performed a systematic review and meta-analysis to evaluate the benefit and harms associated with implantation of toric intraocular lenses (IOLs) during cataract surgery. Outcomes were postoperative uncorrected distance visual acuity (UCDVA) and distance spectacle independence. Harms were evaluated as surgical complications and residual astigmatism. Postoperative astigmatism is an important cause of suboptimal UCDVA and need for distance spectacles. Toric IOLs may correct for preexisting corneal astigmatism at the time of surgery. We performed a systematic literature search in the Embase, PubMed, and CENTRAL databases within the Cochrane Library. We included randomized clinical trials (RCTs) if they compared toric with non-toric IOL implantation (± relaxing incision) in patients with regular corneal astigmatism and age-related cataracts. We assessed the risk of bias using the Cochrane Risk of Bias tool. We assessed the quality of evidence across studies using the GRADE profiler software (available at: www.gradeworkinggroup.org). We included 13 RCTs with 707 eyes randomized to toric IOLs and 706 eyes randomized to non-toric IOLs; 225 eyes had a relaxing incision. We found high-quality evidence that UCDVA was better in the toric IOL group (logarithm of the minimum angle of resolution [logMAR] mean difference, -0.07; 95% confidence interval [CI], -0.10 to -0.04) and provided greater spectacle independence (risk ratio [RR], 0.51; 95% CI, 0.36-0.71) and moderate quality evidence that toric IOL implantation was not associated with an increased risk of complications (RR, 1.73; 95% CI, 0.60-5.04). Residual astigmatism was lower in the toric IOL group than in the non-toric IOL plus relaxing incision group (mean difference, 0.37 diopter [D]; 95% CI, -0.55 to -0.19). We found that toric IOLs provided better UCDVA, greater spectacle independence, and lower amounts of residual astigmatism than non-toric IOLs even when relaxing incisions were used. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Topical Drug Formulations for Prolonged Corneal Anesthesia

PubMed Central

Wang, Liqiang; Shankarappa, Sahadev A.; Tong, Rong; Ciolino, Joseph B.; Tsui, Jonathan H.; Chiang, Homer H.; Kohane, Daniel S.

2013-01-01

Purpose Ocular local anesthetics (OLA’s) currently used in routine clinical practice for corneal anesthesia are short acting and their ability to delay corneal healing makes them unsuitable for long-term use. In this study, we examined the effect on the duration of corneal anesthesia of the site-1 sodium channel blocker tetrodotoxin (TTX), applied with either proparacaine or the chemical permeation enhancer OTAB. The effect of test solutions on corneal healing was also studied. Methods Solutions of TTX, proparacaine, and OTAB, singly or in combination were applied topically to the rat cornea. The blink response, an indirect measure of corneal sensitivity, was recorded using a Cochet-Bonnet esthesiometer, and the duration of corneal anesthesia calculated. The effect of test compounds on the rate of corneal epithelialization was studied in vivo following corneal debridement. Results Combination of TTX and proparacaine resulted in corneal anesthesia that was 8–10 times longer in duration than that from either drug administered alone, while OTAB did not prolong anesthesia. The rate of corneal healing was moderately delayed following co-administration of TTX and proparacaine. Conclusion Co-administration of TTX and proparacaine significantly prolonged corneal anesthesia but in view of delayed corneal re-epithelialization, caution is suggested in use of the combination. PMID:23615270

Small-incision lenticule extraction versus femtosecond lenticule extraction for myopic: a systematic review and Meta-analysis.

PubMed

Wang, Jia-Song; Xie, Hua-Tao; Jia, Ye; Zhang, Ming-Chang

2017-01-01

To examine differences in efficacy, accuracy, safety, aberrations and corneal biomechanical between Small incision lenticule extraction (SMILE) and femtosecond lenticule extraction (FLEx) for myopia. Comprehensive studies were conducted on the PubMed, MEDLINE, EMBASE, and Cochrane Controlled Trials Register before 31 July, 2015. Meta-analyses were performed on the primary outcomes [loss of ≥2 lines of corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) ≥20/20, spherical equivalent (SE) within ±0.50 diopters (D), final refractive SE], secondary outcomes were high-order aberrations (HOAs) and corneal biomechanical [central corneal thickness (CCT), corneal hysteresis (CH) and corneal resistance factor (CRF)]. Seven trials describing a total of 320 eyes with myopia were included in this Meta-analysis. No significant differences were found in the efficacy [UDVA weighted mean difference (WMD) -0.01; 95%CI: -0.04 to 0.01; P =0.37, UDVA ≥20/20, OR 1.49; 95%CI: 0.78 to 2.86; P =0.23], accuracy (SE WMD -0.03; 95%CI: -0.12 to 0.07; P =0.58, SE within ±0.5 D OR 1.25; 95%CI: 0.34 to 4.65; P =0.74), HOAs (WMD -0.04; 95%CI: -0.09 to 0.01; P =0.14) and CCT WMD 1.83; 95%CI: -7.07 to 10.72; P =0.69, CH WMD -0.01; 95%CI: -0.42 to 0.40; P =0.97, CRF WMD 0.17; 95%CI: -0.33 to 0.67; P =0.50) in the last fellow-up. But for safety, FLEx may achieve fewer CDVA lost two or more two lines (OR 11.11; 95%CI: 1.27 to 96.86; P =0.03) than SMILE, however CDVA (WMD 0.00; 95%CI: -0.03 to 0.02; P =0.77) is similar. SMILE and FLEx are comparable in terms of both efficacy, accuracy, aberrations and corneal biomechanical measures in the follow-up, but FLEx seems to be better in safety measures. The results should be interpreted cautiously since relevant evidence is still limited, although it is accumulating. Further large-scale, well-designed randomized controlled trials are urgently needed.

Randomized Controlled Trial Comparing Transepithelial Corneal Cross-linking Using Iontophoresis with the Dresden Protocol in Progressive Keratoconus.

PubMed

Lombardo, Marco; Giannini, Daniela; Lombardo, Giuseppe; Serrao, Sebastiano

2017-06-01

To compare clinical outcomes of transepithelial corneal cross-linking using iontophoresis (T-ionto CL) and standard corneal cross-linking (standard CL) for the treatment of progressive keratoconus 12 months after the operation. Prospective randomized controlled clinical trial. Thirty-four eyes of 25 participants with progressive keratoconus were randomized into T-ionto CL (22 eyes) or standard CL (12 eyes). T-ionto CL was performed using an iontophoresis device with dextran-free 0.1% riboflavin-5-phosphate solution with enhancers and by irradiating the cornea with a 10 mW/cm 2 ultraviolet A device for 9 minutes. Standard CL was performed according to the Dresden protocol. The primary outcome measure was stabilization of keratoconus after 12 months through analysis of maximum simulated keratometry readings (K max , diopters). Other outcome measures were corrected distance visual acuity (CDVA, logarithm of the minimum angle of resolution [logMAR]), manifest spherical equivalent refraction (D), central corneal thickness (CCT, micrometers) and endothelial cell density (ECD). Follow-up examinations were arranged at 3 and 7 days and 1, 3, 6, and 12 months. Twelve months after T-ionto CL and standard CL, K max on average flattened by -0.52±1.30 D (P = 0.06) and -0.82±1.20 D (P = 0.04), respectively. The mean change in CDVA was -0.10±0.12 logMAR (P = 0.003) and -0.03±0.06 logMAR (P = 0.10) after T-ionto CL and standard CL, respectively. The manifest spherical equivalent refraction changed on average by +0.71±1.44 D (P = 0.03) and +0.21±0.76 D (P = 0.38), respectively. The CCT and ECD measures did not change significantly in any group at 12 months. Significant differences in the outcome measures between treatments were found in the first week postoperatively. No complications occurred in the T-ionto CL group; 1 eye (8%) had sterile corneal infiltrates, which did not affect the final visual acuity, in the standard CL group. Significant visual and refractive improvements were found 12 months after T-ionto CL, though the average improvement in corneal topography readings was slightly lower than the Dresden protocol in the same period. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Corneal biomechanical parameters and intraocular pressure: the effect of topical anesthesia

PubMed Central

Ogbuehi, Kelechi C

2012-01-01

Background The intraocular pressures and biomechanical parameters measured by the ocular response analyzer make the analyzer a useful tool for the diagnosis and management of anterior segment disease. This observational study was designed to investigate the effect of topical anesthesia on the parameters measured by the ocular response analyzer: corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc). Methods Two sets of measurements were made for 78 eyes of 39 subjects, approximately 1 week apart. In session 1, each eye of each subject was randomized into one of three groups: polyvinyl alcohol (0.5%), tetracaine hydrochloride (0.5%), or oxybuprocaine hydrochloride (0.4%). In session 2, eyes that were in the polyvinyl alcohol group in session 1 were assigned to the tetracaine group, those in the tetracaine group in session 1 were assigned to oxybuprocaine group, and those in the oxybuprocaine group in session 1 were assigned to the polyvinyl alcohol group. For both sessions, each subject first had his or her central corneal thickness assessed with a specular microscope, followed by measurements of intraocular pressure and corneal biomechanical parameters with the Ocular Response Analyzer. All measurements were repeated for 2 minutes and 5 minutes following the instillation of either polyvinyl alcohol, tetracaine, or oxybuprocaine. The level of statistical significance was 0.05. Results Polyvinyl alcohol, tetracaine hydrochloride, and oxybuprocaine hydrochloride had no statistically significant (P > 0.05) effect on any of the biomechanical parameters of the cornea. There was no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) 2 minutes after the eye drops were instilled in either session. Five minutes after the eye drops were instilled, polyvinyl alcohol showed no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) in either session. Oxybuprocaine and tetracaine caused statistically significant (P < 0.05) reductions in IOPg in session 1, but only tetracaine had a significant (P < 0.05) effect in session 2. Tetracaine also caused a statistically significant (P < 0.05) reduction in IOPcc in session 1. Conclusion The statistically significant effect of topical anesthesia on IOPg varies with the anesthetic used, and while this effect was statistically significant in this study, the small effect is probably not clinically relevant. There was no effect on any of the biomechanical parameters of the cornea. PMID:22791966

Corneal biomechanical parameters and intraocular pressure: the effect of topical anesthesia.

PubMed

Ogbuehi, Kelechi C

2012-01-01

The intraocular pressures and biomechanical parameters measured by the ocular response analyzer make the analyzer a useful tool for the diagnosis and management of anterior segment disease. This observational study was designed to investigate the effect of topical anesthesia on the parameters measured by the ocular response analyzer: corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc). Two sets of measurements were made for 78 eyes of 39 subjects, approximately 1 week apart. In session 1, each eye of each subject was randomized into one of three groups: polyvinyl alcohol (0.5%), tetracaine hydrochloride (0.5%), or oxybuprocaine hydrochloride (0.4%). In session 2, eyes that were in the polyvinyl alcohol group in session 1 were assigned to the tetracaine group, those in the tetracaine group in session 1 were assigned to oxybuprocaine group, and those in the oxybuprocaine group in session 1 were assigned to the polyvinyl alcohol group. For both sessions, each subject first had his or her central corneal thickness assessed with a specular microscope, followed by measurements of intraocular pressure and corneal biomechanical parameters with the Ocular Response Analyzer. All measurements were repeated for 2 minutes and 5 minutes following the instillation of either polyvinyl alcohol, tetracaine, or oxybuprocaine. The level of statistical significance was 0.05. Polyvinyl alcohol, tetracaine hydrochloride, and oxybuprocaine hydrochloride had no statistically significant (P > 0.05) effect on any of the biomechanical parameters of the cornea. There was no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) 2 minutes after the eye drops were instilled in either session. Five minutes after the eye drops were instilled, polyvinyl alcohol showed no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) in either session. Oxybuprocaine and tetracaine caused statistically significant (P < 0.05) reductions in IOPg in session 1, but only tetracaine had a significant (P < 0.05) effect in session 2. Tetracaine also caused a statistically significant (P < 0.05) reduction in IOPcc in session 1. The statistically significant effect of topical anesthesia on IOPg varies with the anesthetic used, and while this effect was statistically significant in this study, the small effect is probably not clinically relevant. There was no effect on any of the biomechanical parameters of the cornea.

Correlation between corneal innervation and inflammation evaluated with confocal microscopy and symptomatology in patients with dry eye syndromes: a preliminary study.

PubMed

Tepelus, Tudor C; Chiu, Gloria B; Huang, Jianyan; Huang, Ping; Sadda, SriniVas R; Irvine, John; Lee, Olivia L

2017-09-01

To evaluate corneal innervation and inflammatory cell infiltration using in vivo confocal microscopy (IVCM) and to correlate these findings with subjective symptoms of dry eye, as measured by the Ocular Surface Disease Index (OSDI) in patients with non-Sjögren's (NSDE) and Sjögren's syndrome dry eyes (SSDE). Central corneal images were prospectively captured from 10 age-matched healthy control eyes, 24 eyes with clinically diagnosed NSDE and 44 eyes with clinically diagnosed SSDE, using IVCM (HRT III RCM). Density, tortuosity and reflectivity of corneal nerves, presence of inflammatory dendritic cells (DCs) and OSDI scores were evaluated. Images obtained by IVCM from 78 eyes were analyzed. The density of nerve fibers was 1562 ± 996 μm/frame in the SSDE group, 2150 ± 1015 μm/frame in the NSDE group and 2725 ± 687 μm/frame in the control group (P < 0.05, ANOVA). In comparison to the control group, the density of nerve fibers was decreased in the SSDE (P < 0.001) and the NSDE groups (P = 0.06), with increased nerve tortuosity and decreased reflectivity in both groups (both P < 0.05). The density of DCs was 71.65 ± 72.54 cells/mm 2 in the SSDE group, 40.33 ± 31.63 cells/mm 2 in the NSDE group and 27.53 ± 5.58 cells/mm 2 in the control group (P < 0.05, ANOVA). In comparison to the control group, the density of DCs was increased in the SSDE (P < 0.001) and the NSDE groups (P = 0.07). Significant correlations were found between the nerve density and DC density (r = -0.57, P < 0.001), between the nerve density and OSDI scores (r = -0.91, P < 0.001) and between the nerve reflectivity and OSDI scores (r = -0.75, P < 0.001). The corneas of eyes affected with NSDE and SSDE are characterized by alterations in corneal innervation and infiltration of inflammatory DCs. Corneal nerve density and reflectivity are correlated with severity of subjective dry eye symptoms, as measured by OSDI score.