Predictive factors for re-bubbling after DMEK: focus on the posterior corneal surface.

PURPOSE: To understand whether the preoperative morphology of the posterior corneal surface influences the rate of re-bubbling after Descemet membrane endothelial keratoplasty (DMEK). METHODS: After retrospectively analyzing the medical records of patients undergoing DMEK, in this multicentric cross-sectional study, we performed a binomial logistic regression analysis to assess significant predictors of re-bubbling and re-transplantation after surgery. Analyzed parameters included the preoperative diagnosis, anterior and posterior surface K1/K2, central corneal thickness, posterior Q value, and other posterior corneal surface parameters evaluated on the elevation maps produced by anterior segment optical coherence tomography. Results were stratified based on the surgeons' experience. RESULTS: We included 202 eyes of 202 patients with a mean age of 69.5 ± 12.4 years; 154 eyes were operated by a high-volume surgeon and 48 by one with less experience; 48 eyes (23.8%) underwent [Formula: see text] 1 re-bubbling and 14(6.9%) [Formula: see text] 1 re-transplantation. The presence of positive/less-negative posterior corneal irregularities and irregularities with greater absolute height had a significantly higher risk of re-bubbling in both the expert and less expert group (OR = 2.85 and 1.42, OR = 3.22 and 3.01, respectively, p < 0.05), whereas more negative posterior K1 and K2 were significant risk factors only in the former group (OR = 0.67 and 0.55, respectively, p < 0.05). Endothelial decompensation other than Fuchs and pseudophakic bullous keratopathy, more negative posterior Q values and smaller distances between center, and the highest/lowest posterior corneal surface irregularity correlated with an increased risk of graft failure (OR 1.23, 1.21, and 1.29, respectively, p < 0.05). CONCLUSION: Posterior corneal surface morphology significantly influences the risk of re-bubbling after DMEK.

Non-invasive quantification of corneal vascularization using anterior segment optical coherence tomography angiography.

The presence of corneal vascularization (CV) interferes with the angiogenic and immune privilege of the cornea, risking rejection in eyes following keratoplasty. Pre-operative (lymph)-angioregression is a promising therapeutic approach, but objective monitoring by non-invasive CV imaging is needed. The purpose of this study was to investigate anterior-segment optical coherence tomography angiography (AS-OCTA) for CV visualization and quantification, and to show its superiority over slit-lamp photography in high-risk eyes scheduled for keratoplasty. This institutional pilot study included 29 eyes of 26 patients (51 ± 16 years, 8 female) with significant CV scheduled for keratoplasty that were imaged by slit-lamp photography (Zeiss SL 800) and AS-OCTA (Zeiss Plex Elite 9000). After manual corneal layer segmentation correction, CV maximum/relative depth was measured with the inbuilt software. Slit-lamp photographs and AS-OCTA images were compared for visualization of vascular details. Angiotool software allowed a semi-automated determination of CV-related parameters in the vascular complex of AS-OCTA images. The predominant causes of CV were the herpes simplex virus keratitis (n = 7) and chemical burn (n = 4). Visualization of vascular morphology in AS-OCTA was superior to slit-lamp photography in all except one eye. Vascular metrics including total vessel length, number of junctions/endpoints, junction density, lacunarity, and vessel area/density were defined using Angiotool, with CV depth localization despite scarring and opacification. AS-OCTA proved effective for angioregressive treatment monitoring. AS-OCTA enables non-invasive and objective three-dimensional visualization of corneal vascularization superior to slit-lamp photography, and could be a precious tool for monitoring angioregressive preconditioning prior to keratoplasty.

Bilateral corneal perforation in Ipilimumab/Nivolumab - associated peripheral ulcerative keratitis.

Purpose: To present a case of immune checkpoint inhibitor-induced bilateral peripheral ulcerative keratitis that progressed to corneal perforation requiring keratoplasty in both eyes. Observations: We describe the course of a 60-year-old man treated with a combination of Ipilimumab and Nivolumab for metastatic melanoma who presented with foreign body sensation and epiphora in both eyes.Bilateral immune-related peripheral ulcerative keratitis was refractory to topical anti-inflammatory therapy, necessitating repetitive, but unsuccessful cyanoacrylate gluing procedure followed by bilateral lamellar mini-keratoplasty. Conclusions and importance: Combined immune checkpoint inhibition revokes the corneal immune privilege and can lead to auto-immune keratitis with recalcitrant progression to ulceration and perforation.

Identification of Treatment Protocols for Effective Cross-Linking of the Peripheral Cornea: An Experimental Study.

INTRODUCTION: This study aimed to test and evaluate modified corneal cross-linking (CXL) protocols regarding improved treatment effects on the peripheral cornea in terms of tissue stability and cellular response. METHODS: Peripheral CXL (pCXL) was performed within a ring of 9-11 mm of 36 human donor corneas with variations in applied energy (5.4, 7.2, and 10 J/cm2) at 9 mW/cm2 irradiance. Each energy level was additionally modulated regarding the oxygen level surrounding the cornea during treatment (21%; 100%). Stress-strain tests with endpoints at 12% strain and collagenase A-assisted digestions to complete digestion were performed to evaluate the rigidity and resistance of treated and control tissue. Further, corneas were processed histologically via TUNEL assay and H&E staining to demonstrate the effects on stromal cells during treatment under varying CXL conditions. RESULTS: Increases in energy dosage achieved significant increases in resistance to stress in all variations except when comparing protocols A and B under normoxic conditions. Supplemental oxygen significantly increased rigidity in protocols B (p < 0.01) and C (p = 0.018). Hyperoxic conditions significantly increased resistance to digestion in all protocols. The number of DNA strand breaks in TUNEL assay staining showed significant increases in all increases in energy as well as with oxygen supplementation. CONCLUSIONS: Increases in energy and supplemental oxygen improved the effect of CXL, though endothelial safety could not be verified with confidence in high-fluence CXL with supplemental oxygen. Results suggest that CXL protocols using 7.2 J/cm2 with 100% O2 or 10 J/cm2 without supplemental oxygen prove most effective without anticipated risk of endothelial damage.

Decompensated cornea with epithelial and stromal edema.

A 66-year-old patient underwent surgery for congenital cataract in both eyes in her first year of life without implantation of an intraocular lens (IOL). In 1994, at the age of 39 years, both eyes received secondary Kelman multiflex-style angle-fixated anterior chamber IOLs (AC IOLs). The surgeries were followed by retinal detachments in both eyes, in the left eye in the same year and in the right eye 4 years later, which were successfully repaired. The patient presented with a decompensated cornea with epithelial and stromal edema in the left eye. The AC IOL axis was oriented from 5- to 8-o'clock position with the haptic contacting the cornea. The distal portion of the inferior-nasal haptic was deeply buried and entrapped in a broad iridocorneal synechia extending between 6- and 8-o'clock positions. The synechia also caused adjacent pupillary distortion and pigment leaf eversion (Figure 1JOURNAL/jcrs/04.03/02158034-202205000-00021/figure1/v/2022-04-22T173532Z/r/image-tiff). The AC IOL in the right eye was well positioned, and the cornea was clear with an endothelial cell count (ECC) of 2160 cells/mm2 and central corneal thickness (CCT) of 650 µm. No ECC was obtainable in the left eye, and CCT was 775 µm (Figure 2JOURNAL/jcrs/04.03/02158034-202205000-00021/figure2/v/2022-04-22T173532Z/r/image-tiff). Visual acuity was 0.8 corrected in the right eye and hand motion in the left eye. Both eyes were normotonic. On optical coherence tomography (OCT) imaging, a broad iridocorneal synechia was visible with a canal corresponding to the deeply buried haptic end of the AC IOL (Figure 3JOURNAL/jcrs/04.03/02158034-202205000-00021/figure3/v/2022-04-22T173532Z/r/image-tiff). Abundant condensed cortical material (Soemmerring's ring) was found behind the iris and above the ciliary body. What would be your surgical options to rehabilitate the patient's left eye considering corneal decompensation caused by haptic contact of an angle-fixated AC IOL and capture of 1 haptic within an iridocorneal synechia extending along 2 clock hours?

Corneal Toxicity Associated With Belantamab Mafodotin Is Not Restricted to the Epithelium: Neuropathy Studied With Confocal Microscopy.

PURPOSE: The purpose of this study was to investigate epithelial and neuronal changes in patients with refractory/relapsed multiple myeloma (RRMM) before/during belantamab mafodotin (belamaf) treatment using confocal microscopy. DESIGN: Retrospective case series. METHODS: RRMM patients underwent best-corrected visual acuity (BCVA) testing and slitlamp examination/photography, followed by corneal confocal microscopy (CCM), to evaluate the epithelium and subbasal nerve plexus (SNP) to measure corneal nerve fiber density (CNFD), branch density (CNBD), and fiber length (CNFL) before and during belamaf treatment. RESULTS: In 14 eyes of 7 patients (4 female, 68 ± 10 years of age) with complete follow-up (4 ± 2 months), the median BCVA dropped from 20/25 (20/25-20/20) to 20/40 (20/200-20/32) in the worse eye at the end of follow-up. Microcystic epithelial changes and ocular surface disease were demonstrated biomicroscopically. CCM showed "grape-like" hyperreflective spots in the central basal epithelium that changed to polymorphous-structured cysts in the superficial epithelium, with no pathology detected at the(peri-)limbal structures. The baseline, normal SNP morphology with a mean CNFD, CNBD, and CNFL of 20.25 ± 7.06/mm2, 19.49 ± 12.34/mm2, and 11.8 ± 3.74mm/mm2 respectively, showed severe fiber fragmentation during follow-up, and an observed complete loss of the SNP at the end of follow-up in all eyes. CONCLUSIONS: This study is the first to illustrate neurotoxic effects of belamaf on the human cornea.

Atezolizumab induced immune-related adverse event mimicking conjunctival metastatic disease.

Purpose: To describe a case of an immune-related adverse event associated with Atezolizumab therapy which was aggravated by ocular surgery. Observations: A 59-year-old man treated with Atezolizumab for metastatic non-small-cell lung cancer developed a conjunctival hypertrophic lesion mistaken for metastatic tissue. Biopsy surgery induced fulminant and multifocal granulomatous conjunctival tissue growth and sterile corneal ulceration. The immune-related adverse event was refractory to topical therapy, with curative success only after introduction of systemic prednisone. Conclusions: Atezolizumab use may be associated with severe and recalcitrant ocular surface inflammation with potential exacerbation after surgical interventions.

Effects of femtosecond laser-assisted trephination on donor tissue in liquid interface as compared to applanated interface.

PURPOSE: To evaluate the effects of femtosecond laser-assisted keratoplasty using a liquid patient interface (L-PI) as opposed to an applanated interface (A-PI) on graft quality and functionality markers. METHODS: Pressure measurements during femtosecond laser-assisted trephination were performed using two groups of 10 porcine eyes. Trephination was performed either in an L-PI or in an A-PI setting. Pressure sensor needles placed intravitreally continuously recorded intraocular pressure during trephination. Twenty paired human donor eyes were used to test the morphological quality of donor tissue after trephination in L-PI and A-PI settings. Optical coherence tomography (OCT) scans were performed before and after trephination. Images were processed using ImageJ and pixel2 . RESULTS: During trephination, pressure measurements with an L-PI were significantly lower than with an A-PI (p = 0.0121). Mean pressure during trephination was 78.1 mmHg ± 37.6 mmHg with L-PI and 188.6 mmHg ± 17.7 mmHg with A-PI. Trephination in A-PI produced a significantly larger increase (p < 0.00001) in donor pachymetry than trephination in L-PI. Significantly lower areas of Descemet folds were achieved in L-PI trephination than in A-PI trephination (p < 0.01). There was no significant difference in circularity between A-PI and L-PI (p = 0.27). Total time required for trephination was comparable between L-PI and A-PI (p = 0.45). Time taken to reach working vacuum was achieved significantly more quickly in L-PI (p < 0.05). CONCLUSION: Femtosecond laser-assisted L-PI keratoplasty appears to be a promising method to decrease stress to donor and recipient tissue during femtosecond laser-assisted trephination. Results showed favourable donor tissue morphology markers after L-PI trephination.

Endothelial Safety and Efficacy of Ex Vivo Collagen Cross-linking of Human Corneal Transplants.

PURPOSE: To assess endothelial safety and efficacy of ex vivo corneal collagen cross-linking (CXL) in human corneal transplants stored in 2 different culture media. DESIGN: Fellow-eye controlled laboratory study of ex vivo human donor corneas. METHODS: Three sets of paired human donor corneas, 5 pairs each, were stored in organ culture medium before deswelling either at 31 C or at room temperature. One eye of each pair was cross-linked by 0.1% riboflavin in hydroxylpropyl methylcellulose (HPMC) instillation for 10 minutes followed by 10 minutes of ultraviolet-A (9 mW/cm2) irradiation while contralateral eyes served as controls. In Set 1, endothelial cell densities were determined. In Set 2, paired samples were assigned to the 2 deswelling media and CXL efficacy was assessed comparing to untreated controls using collagenase-A-assisted enzymatic digestion. In Set 3, biomechanical testing was performed in the eye pairs (treated vs control) by stress/strain measurements. RESULTS: There was no difference in endothelial cell counts between CXL samples and controls (P = .21). No statistically significant difference in digestion dynamics was found between tissues stored in the 2 different culture media. Complete enzymatic digestion was slowed down by 3 hours in the cross-linked samples (P = .036). Stress needed for a 12% strain was increased by 34% in the treatment group compared to control (P = .04). CONCLUSIONS: Ex vivo CXL of human donor tissue is an effective and safe procedure with no difference regarding efficacy between 2 commercially available deswelling media. Biochemical and biomechanical resistance were significantly increased after CXL. Patients requiring keratoplasty owing to corneal melting might benefit from the strengthening effect of preoperative CXL of donor tissue.

Large Field of View Corneal Epithelium and Bowman's Layer Thickness Maps in Keratoconic and Healthy Eyes.

PURPOSE: To assess differences between epithelium thickness (ET) and Bowman's layer thickness (BLT) maps in keratoconic eyes and healthy eyes. DESIGN: Cross-sectional study. METHODS: Setting: institutional. STUDY POPULATION: 47 patients (1 eye) with keratoconus (KC) and 20 healthy subjects (1 eye). OBSERVATION PROCEDURE: epithelium and Bowman's layer measurements were performed by using custom-designed polarization-sensitive optical coherence tomography (PS-OCT) with a conical scanning optics design. En face corneal ET and BLT maps with a diameter of 11 mm were computed. Main outcome measurements were mean ET and BLT of 25 sectors; the thinnest (minET, minBLT) and thickest sectors (maxET, maxBLT) were assessed. Ratios between thinnest/thickest sectors (R1) and between mean ET and BLT of the inferior temporal quadrant/superior nasal quadrant (R2) were calculated (R1ET, R1BLT; R2ET, R2BLT). Receiver operator characteristic (ROC) curve analysis was used to assess the diagnostic power of statistically different parameters. RESULTS: In healthy eyes, smooth ET maps were observed. KC eyes showed a "doughnut pattern." The BLT maps of healthy eyes had a smooth appearance, but highly irregular "moth"-like damage pattern could be observed in keratoconic eyes. Highest area under the curve values were found for the thinnest sector of the BLT map, the R1ET, and the thinnest sector of the ET map. CONCLUSIONS: PS-OCT imaging enables the visualization of significant differences of the corneal epithelium and the Bowman's layer in en face maps covering almost the entire cornea. ET and BLT profiles could clearly show their diagnostic importance for the distinguishing of keratoconic eyes and healthy eyes.

Corneal crosslinking for pellucid marginal degeneration.

PURPOSE: To investigate the efficacy of corneal crosslinking (CXL) for pellucid marginal degeneration (PMD). SETTING: Medical University of Vienna. DESIGN: Retrospective study. METHODS: In eyes with a crab-claw pattern on corneal topography of a study cohort of 808 eyes, manual measurements of the cornea's thinnest point on the inferior vertical Scheimpflug image (mCTi) and on the superior vertical Scheimpflug image (mCTs) were conducted. Eyes with paralimbal thinning were supposed as having PMD and included. A ratio between mCTi and mCTs was calculated. CXL was performed by irradiation of the inferior periphery of the cornea. During the follow-up, the mCTi, the mean keratometry (K) values in a central zone of 5.0 mm and in a 2.5 mm zone of the inferior cornea and the topographical corneal astigmatism were measured. The corrected distance visual acuity (CDVA) was also evaluated. Patients were followed postoperatively for 12 months. RESULTS: Forty-eight eyes showed a crab-claw pattern in corneal topography. Twenty-two eyes matched the inclusion criteria for PMD and 16 eyes underwent CXL. The mCTi increased during the 12-month follow-up. The K value in the 2.5 mm zone of the inferior cornea decreased after 1 year, whereas the K value in the central zone of 5.0 mm remained stable. The corneal astigmatism continuously decreased, and the CDVA improved after 1 year. CONCLUSION: Manual pachymetric measurements in Scheimpflug images showed the potential for screening for PMD and the evaluation of the efficacy of CXL in eyes with PMD in the study cohort. A thickening of the mCTi and a flattening in the inferior part of the cornea was observed.

Ultrahigh-resolution anterior segment optical coherence tomography for analysis of corneal microarchitecture during wound healing.

PURPOSE: To employ ultrahigh-resolution (UHR) optical coherence tomography (OCT) for investigation of the early wound healing process in corneal epithelium. METHODS: A custom-built UHR-OCT system assessed epithelial healing in human keratoconic cornea after epi-off crosslinking (CXL) procedure and a wound healing model in rabbits with iatrogenic corneal injury. 3D OCT data sets enhanced obtaining epithelial thickness maps and evaluation of reepithelization stage. Accompanying changes in deeper corneal microarchitecture were analysed. RESULTS: The mean central corneal thickness in 40 eyes with keratoconus at baseline was 482.7 ± 38.2 µm, while mean central epithelial thickness (CET) was 43.8 ± 6.4 µm. At the final visit 20 ± 5 days post-CXL procedure, CET was 35.0 ± 5.8 µm, significantly thinner after reepithelization (p < 0.001). Surgical success was assessed at the final visit through the demarcation line (DL), identified at 43.7 ± 13.5% stromal depth. In rabbits, the mean CET in 20 eyes at baseline was 35.9 ± 2.6 µm. In rabbits that revealed complete wound closure (10/20 eyes) at the last study day at 72 hr, CET was significantly thinner compared to baseline (30.4 ± 2.8 µm versus 35.4 ± 2.9 µm, p = 0.005). An intra-stromal landmark indicating early keratocyte apoptosis was measured at 30.0 ± 5.1% stromal depth. Epithelial thickness maps showed the time-course of corneal healing. CONCLUSION: Ultrahigh-resolution (UHR)-OCT provided precise assessment of epithelial wound and its healing by 3D-mapping. In addition, microarchitectural changes in the cornea in early phases of epithelial healing were revealed.

CorneaNet: fast segmentation of cornea OCT scans of healthy and keratoconic eyes using deep learning.

Deep learning has dramatically improved object recognition, speech recognition, medical image analysis and many other fields. Optical coherence tomography (OCT) has become a standard of care imaging modality for ophthalmology. We asked whether deep learning could be used to segment cornea OCT images. Using a custom-built ultrahigh-resolution OCT system, we scanned 72 healthy eyes and 70 keratoconic eyes. In total, 20,160 images were labeled and used for the training in a supervised learning approach. A custom neural network architecture called CorneaNet was designed and trained. Our results show that CorneaNet is able to segment both healthy and keratoconus images with high accuracy (validation accuracy: 99.56%). Thickness maps of the three main corneal layers (epithelium, Bowman's layer and stroma) were generated both in healthy subjects and subjects suffering from keratoconus. CorneaNet is more than 50 times faster than our previous algorithm. Our results show that deep learning algorithms can be used for OCT image segmentation and could be applied in various clinical settings. In particular, CorneaNet could be used for early detection of keratoconus and more generally to study other diseases altering corneal morphology.

Mapping of Corneal Layer Thicknesses With Polarization-Sensitive Optical Coherence Tomography Using a Conical Scan Pattern.

Purpose: We demonstrate segmentation and mapping of corneal layers (epithelium, Bowman's layer, and stroma) across the entire cornea (limbus to limbus), using additional contrast provided by polarization-sensitive optical coherence tomography (PS-OCT) and analyze the reproducibility of the procedure. Methods: A custom built PS-OCT system operating at 1045 nm central wavelength with conical scanning was used for image acquisition. Conical scanning allows for almost perpendicular beam incidence on the corneal surface and provides good signal quality over the entire field of view. Epithelium, Bowman's layer, and stroma were segmented using the additional contrast provided by PS-OCT. Thickness maps were computed and analyzed in sectors. Both eyes of 20 healthy volunteers were imaged at least three times to test this method and to quantify reproducibility. Results: Thickness maps of the epithelium show significant (P < 0.001) superior thinning and an inferior thickening. Bowman's layer appears homogeneous within the central 7 to 8 mm diameter of the cornea and gets thinner toward the periphery until this layer disappears between 4 and 5.5 mm eccentricity from the center. Intersubject variations of the measured thicknesses of epithelium (coefficient of variation [CV] ∼8%), Bowman's layer (CV∼25%), and stroma (CV∼10%) were observed. Very good reproducibility of thickness measurements of epithelium (CV < 3%), Bowman's layer (CV < 5%), and stroma (CV < 2%) was found. Furthermore, a significant correlation (P < 0.001) between layer thicknesses of the right and left eyes of the same subject was found. Conclusions: PS-OCT with conical scanning is a feasible approach for determining thickness maps of corneal layers on a large field of view with high reproducibility.

Correlation between central stromal demarcation line depth and changes in K values after corneal cross-linking (CXL).

PURPOSE: A stromal demarcation line (DL) after corneal cross-linking (CXL) has lately been suggested as a surrogate parameter for the success of CXL. The aim of this study was to investigate the correlation between depth of the central DL 1 month and the change in K values 12 months after CXL. METHODS: Treatment-naive subjects with keratoconus were treated using an accelerated CXL protocol [A-CXL(9*10)]. Depth of the DL/relative depth of the DL (DL%) was measured using Visante OCT imaging 1 month postoperatively (OP). Kmax/K2.5 (preOP) and change in Kmax/K2.5 (preOP - 12 months postOP) were assessed using corneal tomography (Pentacam HR, Oculus GmBH). RESULTS: Forty eyes were treated following the A-CXL(9*10). The mean DL depth was 200 ± 99 µm (range 71 to 479)/mean DL% = 42.70 ± 20.00% (range 17-90). There was no statistically significant correlation between stromal depth of the DL and change in Kmax or K2.5, respectively (Spearman rho DL/∆Kmax - 0.14 and DL/∆K2.5 - 0.14). Between DL% and the changes in maximum K values or K2.5, no statistically significant correlation was found as well (Spearman rho DL%/∆Kmax - 0.10 and DL%/∆K2.5 - 0.19). Mean change in Kmax after 12 months was - 0.68 ± 2.26 diopters (D) (median - 0.35 D) and - 0.82 ± 1.6 D (median - 0.65 D) for K2.5 (p = 0.07; p = 0.02). CONCLUSIONS: No statistically significant correlation was found between the stromal central depth of the DL and any outcome parameter for CXL after 12 months. Therefore, the interpretation of the DL as a predictive parameter for the effect of the procedure may not apply.

Distinguishing Keratoconic Eyes and Healthy Eyes Using Ultrahigh-Resolution Optical Coherence Tomography-Based Corneal Epithelium Thickness Mapping.

PURPOSE: To find differences in epithelial thickness (ET) maps of eyes with keratoconus (KC) and healthy eyes. DESIGN: Institutional cross-sectional study. METHODS: In this study 40 keratoconic eyes and 76 healthy eyes were scanned using a custom-built ultrahigh-resolution optical coherence tomography system. Automated segmentation ET maps with 17 subsectors were calculated (central, temporal inferior, temporal superior, nasal inferior, and nasal superior area). The thinnest point of the epithelium (minET), the thickest point of the epithelium (maxET), and the thinnest point diagonally opposing the thickest point (ETmax/op) were additional parameters. Ratios were calculated as follows: minET/diagonally opposing point (R1), maxET/diagonally opposing point (R2), inferior temporal area/superior nasal area (RTI/NS), and inferior/superior hemisphere (RI/S). Furthermore, collected parameters were analyzed regarding their diagnostic accuracy (area under the curve; AUC). RESULTS: Statistically significant differences were as follows: central ET, 46.25 ± 2.56/50.91 ± 1.66; minET, 38.50 ± 2.10/46.79 ± 1.27; ETmax/op, 47.14 ± 2.45/49.60 ± 1.57; temporal inferior area: 43.93 ± 2.95/51.04 ± 1.51 (all mean ± standard deviation, µm); R1, 0.76 ± 0.09/0.93 ± 0.04; R2, 1.08 ± 0.04/1.21 ± 0.16; RTI/NS, 0.85 ± 0.08/1.02 ± 0.04; RI/S: 0.92 ± 0.07/0.99 ± 0.02. AUC values were R1: 0.979 (confidence interval [CI]: 0.957-1.000), RTI/NS: 0.977 (CI: 0.951-1.000), and minET: 0.928 (CI: 0.880-0.977). CONCLUSIONS: Epithelial thickness maps could clearly visualize different ET patterns. Parameters with the highest potential of diagnostic discrimination between eyes with KC and healthy eyes were, in descending order, R1, RTI/NS, and minET. Consequently, epithelial thickness irregularity and asymmetry seem to be the most promising diagnostic factor in terms of discriminating between keratoconic eyes and healthy eyes.

Autophagy mediates cell cycle response by regulating nucleocytoplasmic transport of PAX6 in limbal stem cells under ultraviolet-A stress.

Limbal stem cells (LSC) account for homeostasis and regeneration of corneal epithelium. Solar ultraviolet A (UVA) is the major source causing oxidative damage in the ocular surface. Autophagy, a lysosomal degradation mechanism, is essential for physiologic function and stress defense of stem cells. PAX6, a master transcription factor governing corneal homeostasis by regulating cell cycle and cell fate of LSC, responds to oxidative stress by nucleocytoplasmic shuttling. Impaired autophagy and deregulated PAX6 have been reported in oxidative stress-related ocular surface disorders. We hypothesize a functional role for autophagy and PAX6 in LSC's stress response to UVA. Therefore, human LSC colonies were irradiated with a sub-lethal dose of UVA and autophagic activity and intracellular reactive oxygen species (ROS) were measured by CYTO-ID assay and CM-H2DCFDA live staining, respectively. Following UVA irradiation, the percentage of autophagic cells significantly increased in LSC colonies while intracellular ROS levels remained unaffected. siRNA-mediated knockdown (KD) of ATG7 abolished UVA-induced autophagy and led to an excessive accumulation of ROS. Upon UVA exposure, LSCs displayed nuclear-to-cytoplasmic translocation of PAX6, while ATG7KD or antioxidant pretreatment largely attenuated the intracellular trafficking event. Immunofluorescence showing downregulation of proliferative marker PCNA and induction of cell cycle regulator p21 indicates cell cycle arrest in UVA-irradiated LSC. Abolishing autophagy, adenoviral-assisted restoration of nuclear PAX6 or antioxidant pretreatment abrogated the UVA-induced cell cycle arrest. Adenoviral expression of an ectopic PAX gene, PAX7, did not affect UVA cell cycle response. Furthermore, knocking down PAX6 attenuated the cell cycle progression of irradiated ATG7KD LSC by de-repressing p21 expression. Collectively, our data suggest a crosstalk between autophagy and PAX6 in regulating cell cycle response of ocular progenitors under UVA stress. Autophagy deficiency leads to impaired intracellular trafficking of PAX6, perturbed redox balance and uncurbed cell cycle progression in UVA-stressed LSCs. The coupling of autophagic machinery and PAX6 in cell cycle regulation represents an attractive therapeutic target for hyperproliferative ocular surface disorders associated with solar radiation.

Ultrahigh-resolution OCT imaging of the human cornea.

We present imaging of corneal pathologies using optical coherence tomography (OCT) with high resolution. To this end, an ultrahigh-resolution spectral domain OCT (UHR-OCT) system based on a broad bandwidth Ti:sapphire laser is employed. With a central wavelength of 800 nm, the imaging device allows to acquire OCT data at the central, paracentral and peripheral cornea as well as the limbal region with 1.2 µm x 20 µm (axial x lateral) resolution at a rate of 140 000 A-scans/s. Structures of the anterior segment of the eye, not accessible with commercial OCT systems, are visualized. These include corneal nerves, limbal palisades of Vogt as well as several corneal pathologies. Cases such as keratoconus and Fuchs's endothelial dystrophy as well as infectious changes caused by diseases like Acanthamoeba keratitis and scarring after herpetic keratitis are presented. We also demonstrate the applicability of our system to visualize epithelial erosion and intracorneal foreign body after corneal trauma as well as chemical burns. Finally, results after Descemet's membrane endothelial keratoplasty (DMEK) are imaged. These clinical cases show the potential of UHR-OCT to help in clinical decision-making and follow-up. Our results and experience indicate that UHR-OCT of the cornea is a promising technique for the use in clinical practice, but can also help to gain novel insight in the physiology and pathophysiology of the human cornea.

Effect of a Matrix Therapy Agent on Corneal Epithelial Healing After Standard Collagen Cross-linking in Patients With Keratoconus: A Randomized Clinical Trial.

IMPORTANCE: Corneal abrasions are frequent after standard (epithelium-off [epi-off]) corneal collagen cross-linking (CXL) in patients with progressive keratoconus. A new matrix therapy agent (ReGeneraTing Agent [RGTA]) has been developed to promote corneal wound healing. OBJECTIVE: To assess the effect of the new type of matrix therapy agent on corneal wound healing after epi-off CXL in patients with keratoconus. DESIGN, SETTING, AND PARTICIPANTS: This double-masked randomized clinical trial enrolled 40 patients with keratoconus undergoing epi-off CXL from July 18, 2014, to October 21, 2015, when the last follow-up was completed. The analysis of the intention-to-treat population was performed at the Department of Clinical Pharmacology in cooperation with the Center for Medical Physics and Biomedical Engineering and the Department of Ophthalmology and Optometry of the Medical University of Vienna. INTERVENTIONS: Patients were randomized to receive the matrix therapy agent or hyaluronic acid-containing eyedrops, 0.1%, every other day starting immediately after surgery. The size of the corneal defect was measured using ultrahigh-resolution optical coherence tomography (OCT) and slitlamp photography (SLP) with fluorescein staining. MAIN OUTCOMES AND MEASURES: Corneal wound healing rate, defined as the size of the defect over time. RESULTS: Among the 40 patients undergoing epi-off CXL (31 men; 9 women; mean [SD] age, 31 [10] years), wound healing was significantly faster in the matrix therapy agent group compared with the hyaluronic acid group (4.4 vs 6.1 days; mean difference, 1.7 days; 95% CI, 0.25-3.15 days; P = .008). The defect size was smaller in the matrix therapy agent group than in the hyaluronic acid group as measured with OCT (12.4 vs 23.9 mm2; mean difference, 11.6 mm2; 95% CI, 0.8-23.5 mm2; P = .045) and SLP (11.9 vs 23.5 mm2; mean difference, 11. 6 mm2; 95% CI, 1.3-22.9 mm2; P = .03). A correlation between the defect size measured with OCT and SLP was found (r = 0.89; P < .001). No ocular or serious adverse events occurred. CONCLUSIONS AND RELEVANCE: Use of a new matrix therapy agent appears to improve corneal wound healing after CXL in patients with keratoconus. Monitoring of corneal wound healing using ultrahigh-resolution OCT might be an attractive alternative to SLP because OCT provides an objective and 3-dimensional evaluation of the corneal defect. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT02119039.