The Neuropeptide α-Melanocyte-Stimulating Hormone Prevents Persistent Corneal Edema following Injury.

Corneal endothelial cells (CEnCs) regulate corneal hydration and maintain tissue transparency through their barrier and pump function. However, these cells exhibit limited regenerative capacity following injury. Currently, corneal transplantation is the only established therapy for restoring endothelial function, and there are no pharmacologic interventions available for restoring endothelial function. This study investigated the efficacy of the neuropeptide α-melanocyte-stimulating hormone (α-MSH) in promoting endothelial regeneration during the critical window between ocular injury and the onset of endothelial decompensation using an established murine model of injury using transcorneal freezing. Local administration of α-MSH following injury prevented corneal edema and opacity, reduced leukocyte infiltration, and limited CEnC apoptosis while promoting their proliferation. These results suggest that α-MSH has a proregenerative and cytoprotective function on CEnCs and shows promise as a therapy for the prevention and management of corneal endothelial dysfunction.

The Neuropeptide Alpha-Melanocyte-Stimulating Hormone Is Critical for Corneal Endothelial Cell Protection and Graft Survival after Transplantation.

Corneal transplantation is the most common form of tissue transplantation. The success of corneal transplantation mainly relies on the integrity of corneal endothelial cells (CEnCs), which maintain tissue transparency by pumping out excess water from the cornea. After transplantation, the rate of CEnC loss far exceeds that seen with normal aging, which can threaten sight. The underlying mechanisms are poorly understood. Alpha-melanocyte-stimulating hormone (α-MSH) is a neuropeptide that is constitutively found in the aqueous humor with both cytoprotective and immunomodulatory effects. The curent study found high expression of melanocortin 1 receptor (MC1R), the receptor for α-MSH, on CEnCs. The effect of α-MSH/MC1R signaling on endothelial function and allograft survival in vitro and in vivo was investigated using MC1R signaling-deficient mice (Mc1re/e mice with a nonfunctional MC1R). Herein, the results indicate that in addition to its well-known immunomodulatory effect, α-MSH has cytoprotective effects on CEnCs after corneal transplantation, and the loss of MC1R signaling significantly decreases long-term graft survival in vivo. In conclusion, α-MSH/MC1R signaling is critical for CEnC function and graft survival after corneal transplantation.

Dysregulation of DNA repair genes in Fuchs endothelial corneal dystrophy.

Fuchs Endothelial Corneal Dystrophy (FECD), a late-onset oxidative stress disorder, is the most common cause of corneal endothelial degeneration and is genetically associated with CTG repeat expansion in Transcription Factor 4 (TCF4). We previously reported accumulation of nuclear (nDNA) and mitochondrial (mtDNA) damage in FECD. Specifically, mtDNA damage was a prominent finding in development of disease in the ultraviolet-A (UVA) induced FECD mouse model. We hypothesize that an aberrant DNA repair may contribute to the increased DNA damage seen in FECD. We analyzed differential expression profiles of 84 DNA repair genes by real-time PCR arrays using Human DNA Repair RT-Profiler plates using cDNA extracted from Descemet's membrane-corneal endothelium (DM-CE) obtained from FECD patients with expanded (>40) or non-expanded (<40) intronic CTG repeats in TCF4 gene and from age-matched normal donors. Change in mRNA expression of <0.5- or >2.0-fold in FECD relative to normal was set as cutoff for down- or upregulation. Downregulated mitochondrial genes were further validated using the UVA-based mouse model of FECD. FECD specimens exhibited downregulation of 9 genes and upregulation of 8 genes belonging to the four major DNA repair pathways, namely, base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), and double strand break (DSB) repair, compared to normal donors. MMR gene MSH2 and BER gene POLB were preferentially upregulated in expanded FECD. BER genes LIG3 and NEIL2, DSB repair genes PARP3 and TOP3A, NER gene XPC, and unclassified pathway gene TREX1, were downregulated in both expanded and non-expanded FECD. MtDNA repair genes, Lig3, Neil2, and Top3a, were also downregulated in the UVA-based mouse model of FECD. Our findings identify impaired DNA repair pathways that may play an important role in DNA damage due to oxidative stress as well as genetic predisposition noted in FECD.

Ultraviolet A light induces DNA damage and estrogen-DNA adducts in Fuchs endothelial corneal dystrophy causing females to be more affected.

Fuchs endothelial corneal dystrophy (FECD) is a leading cause of corneal endothelial (CE) degeneration resulting in impaired visual acuity. It is a genetically complex and age-related disorder, with higher incidence in females. In this study, we established a nongenetic FECD animal model based on the physiologic outcome of CE susceptibility to oxidative stress by demonstrating that corneal exposure to ultraviolet A (UVA) recapitulates the morphological and molecular changes of FECD. Targeted irradiation of mouse corneas with UVA induced reactive oxygen species (ROS) production in the aqueous humor, and caused greater CE cell loss, including loss of ZO-1 junctional contacts and corneal edema, in female than male mice, characteristic of late-onset FECD. UVA irradiation caused greater mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) damage in female mice, indicative of the sex-driven differential response of the CE to UVA, thus accounting for more severe phenotype in females. The sex-dependent effect of UVA was driven by the activation of estrogen-metabolizing enzyme CYP1B1 and formation of reactive estrogen metabolites and estrogen-DNA adducts in female but not male mice. Supplementation of N-acetylcysteine (NAC), a scavenger of reactive oxygen species (ROS), diminished the morphological and molecular changes induced by UVA in vivo. This study investigates the molecular mechanisms of environmental factors in FECD pathogenesis and demonstrates a strong link between UVA-induced estrogen metabolism and increased susceptibility of females for FECD development.

Activation of PINK1-Parkin-Mediated Mitophagy Degrades Mitochondrial Quality Control Proteins in Fuchs Endothelial Corneal Dystrophy.

Corneal endothelium (CE) is a monolayer of mitochondria-rich cells, critical for maintaining corneal transparency compatible with clear vision. Fuchs endothelial corneal dystrophy (FECD) is a heterogeneous, genetically complex disorder, where oxidative stress plays a key role in the rosette formation during the degenerative loss of CE. Increased mitochondrial fragmentation along with excessive mitophagy activation has been detected in FECD; however, the mechanism of aberrant mitochondrial dynamics in CE cell loss is poorly understood. Here, the role of oxidative stress in mitophagy activation in FECD is investigated. Immunoblotting of FECD ex vivo specimens revealed an accumulation of PINK1 and phospho-Parkin (Ser65) along with loss of total Parkin and total Drp1. Similarly, modeling of rosette formation with menadione (MN), led to phospho-Parkin accumulation in fragmented mitochondria resulting in mitophagy-induced mitochondrial clearance, albeit possibly in a PINK1-independent manner. Loss of PINK1, phospho-Drp1, and total Drp1 was prominent after MN-induced oxidative stress, but not after mitochondrial depolarization by carbonyl cyanide m-chlorophenyl hydrazone. Moreover, MN-induced mitophagy led to degradation of Parkin along with sequestration of Drp1 and PINK1 that was rescued by mitophagy inhibition. This study shows that in FECD, intracellular oxidative stress induces Parkin-mediated mitochondrial fragmentation where endogenous Drp1 and PINK1 are sequestered and degraded by mitophagy during degenerative loss of post-mitotic cells of ocular tissue.

Vasoactive Intestinal Peptide Promotes Corneal Allograft Survival.

Corneal transplantation is the most prevalent form of tissue transplantation. The success of corneal transplantation mainly relies on the integrity of corneal endothelial cells (CEnCs), which maintain graft transparency. CEnC density decreases significantly after corneal transplantation even in the absence of graft rejection. To date, different strategies have been used to enhance CEnC survival. The neuropeptide vasoactive intestinal peptide (VIP) improves CEnC integrity during donor cornea tissue storage and protects CEnCs against oxidative stress-induced apoptosis. However, little is known about the effect of exogenous administration of VIP on corneal transplant outcomes. We found that VIP significantly accelerates endothelial wound closure and suppresses interferon-γ- and tumor necrosis factor-α-induced CEnC apoptosis in vitro in a dose-dependent manner. In addition, we found that intracameral administration of VIP to mice undergoing syngeneic corneal transplantation with endothelial injury increases CEnC density and decreases graft opacity scores. Finally, using a mouse model of allogeneic corneal transplantation, we found for the first time that treatment with VIP significantly suppresses posttransplantation CEnC loss and improves corneal allograft survival.

Limbal Cysts: A Subset Exhibiting Cornea-Specific Cytokeratins.

Two cases of limbal cysts lined by nonkeratinizing epithelium were studied with a panel of cytokeratins. One was a long-standing lesion in a 30-year-old man, whereas the other was excised from a 40-year-old man following pterygium surgery. Each cyst was immunostained with a panel of cytokeratins that were specific exclusively and separately for corneal and conjunctival epithelia. The epithelial lining of each cyst was CK12 positive for corneal epithelium and CK13 negative for conjunctival epithelium. It is hypothesized that a subset of corneoscleral cysts contain corneal epithelium, probably derived from a type of limbal stem cell differentiation.

Existence of Neural Crest-Derived Progenitor Cells in Normal and Fuchs Endothelial Dystrophy Corneal Endothelium.

Human corneal endothelial cells are derived from neural crest and because of postmitotic arrest lack competence to repair cell loss from trauma, aging, and degenerative disorders such as Fuchs endothelial corneal dystrophy (FECD). Herein, we identified a rapidly proliferating subpopulation of cells from the corneal endothelium of adult normal and FECD donors that exhibited features of neural crest-derived progenitor (NCDP) cells by showing absence of senescence with passaging, propensity to form spheres, and increased colony forming efficacy compared with the primary cells. The collective expression of stem cell-related genes SOX2, OCT4, LGR5, TP63 (p63), as well as neural crest marker genes PSIP1 (p75(NTR)), PAX3, SOX9, AP2B1 (AP-2ß), and NES, generated a phenotypic footprint of endothelial NCDPs. NCDPs displayed multipotency by differentiating into microtubule-associated protein 2, ß-III tubulin, and glial fibrillary acidic protein positive neurons and into p75(NTR)-positive human corneal endothelial cells that exhibited transendothelial resistance of functional endothelium. In conclusion, we found that mitotically incompetent ocular tissue cells contain adult NCDPs that exhibit a profile of transcription factors regulating multipotency and neural crest progenitor characteristics. Identification of normal NCDPs in FECD-affected endothelium holds promise for potential autologous cell therapies.

Validity and Reliability of a Novel Ocular Pain Assessment Survey (OPAS) in Quantifying and Monitoring Corneal and Ocular Surface Pain.

PURPOSE: To validate the Ocular Pain Assessment Survey (OPAS), specifically designed to measure ocular pain and quality of life for use by eye care practitioners and researchers. DESIGN: A single-center cohort study was conducted among patients with and without corneal and ocular surface pain at initial and follow-up visits over a 6-month period. The content of the OPAS was guided by literature review, a body of experts, and incorporating conceptual frameworks from existing pain questionnaires. The Wong-Baker FACES Pain Rating Scale served as the gold standard for measuring the intensity of ocular pain. PARTICIPANTS: A total of 102 patients aged 18 to 80 years completed the OPAS at the initial visit. A total of 21 patients were followed up after treatment. METHODS: Indices of validity and internal consistency (Spearman's rank-order, rs, or Pearson's correlation coefficients, rp), and coefficient of reliability (Cronbach's α) were determined in addition to equivalence testing, exploratory factor analysis (EFA), and diagnostic analysis. MAIN OUTCOME MEASURES: Eye pain intensity was the primary outcome measure, and interference with quality of life (QoL), aggravating factors, associated factors, associated non-eye pain intensity, and self-reported symptomatic relief were the secondary outcome measures. RESULTS: The OPAS had criterion validity at both initial (rs = 0.71; n = 102; P < 0.01) and follow-up visits (rs = 0.97; n = 21; P < 0.01). Equivalence tests yielded OPAS and gold standard equivalence for both the initial and follow-up visits. The EFA supported 6 subscales (eye pain intensity at 24 hours and 2 weeks, non-eye pain intensity, QoL, aggravating factors, and associated factors) confirming multidimensionality. Cronbach's α >0.83 for all subscales established strong internal consistency, which correlated with the gold standard, including 24-hour eye pain intensity and QoL interference scores (rp = 0.81, 0.64, respectively P < 0.001). At follow-up, reduction in pain scores was accompanied by improvement in all dimensions of the OPAS. Percentage change in QoL correlated to percentage change in the gold standard (rp = 0.53; P < 0.05). The OPAS was sensitive (94%), specific (81%), and accurate (91%), with a diagnostic odds ratio >50. CONCLUSIONS: The OPAS is a valid, reliable, and responsive tool with strong psychometric and diagnostic properties in the multidimensional quantification of corneal and ocular surface pain intensity, and QoL.

Differentiation potential of limbal fibroblasts and bone marrow mesenchymal stem cells to corneal epithelial cells.

The cornea is covered by a stratified epithelium that is renewed by stem cells located in the peripheral region of the cornea known as the limbus. This stroma of the limbus contains stromal keratocytes that, when expanded in culture, are termed limbal fibroblasts (LFs). It is thought that LFs exhibit similar characteristics to bone marrow mesenchymal stem cells (BM MSCs) and help maintain the epithelial stem cell phenotype in the limbal region. In this study, we aimed at reprogramming stage-specific embryonic antigen-4 (SSEA4+) LFs and BM MSCs into corneal epithelial lineage using a three-dimensional culture system and embryonic stem cell medium. After enrichment, SSEA4+ cells showed a higher level of stem cell marker expression such as Sox2, Oct4, Nanog, Rex1, ABCG2, and TRA-1-60, and colony-forming efficiency than did SSEA4- cells. SSEA4+, as compared to SSEA4- cells, had a greater propensity to form spheres that, in turn, were induced into ectodermal lineage and further differentiated into functional corneal epithelium. Results show that LFs were similar to BM MSCs in marker profiles, and together with the differences noted between SSEA4+ and SSEA4- cells, point to LFs' being tissue-specific MSCs. However, LFs showed a greater potential for differentiation into corneal epithelium, indicating the potential importance of tissue-specific adult progenitors in their reprogramming capacity into cells of interest. This study opens a new avenue for investigating the molecular mechanism involved in maintaining a limbal stem cell niche and thus a potentially important clinical application to treat corneal epithelial stem cell loss.

Outcomes of phacoemulsification in patients with chronic ocular graft-versus-host disease.

PURPOSE: The purpose of this study was to evaluate the outcomes of phacoemulsification in patients with ocular graft-versus-host disease (GVHD). METHODS: The occurrence of cataracts, cataract surgery, and its outcomes were analyzed in the medical records of 229 patients (458 eyes) with ocular GVHD. Outcome measures included pre- and postoperative corrected distance visual acuity (CDVA) and the rate of postoperative complications. RESULTS: Of the 458 eyes evaluated, 58 were pseudophakic; from the 400 phakic eyes, 238 (59 %) presented with cataracts and 62 (26 %) underwent cataract surgery. Analysis of postoperative complications and visual outcomes at 1 month was performed in 51 eyes in which detailed surgical and immediate postoperative records were available. Preoperatively, the mean CDVA was 0.67 ± 0.57 LogMAR (Snellen 20/93), improving postoperatively to 0.17 ± 0.18 (Snellen 20/29) at 1 month (P < 0.0001), and to 0.13 ± 0.14 (Snellen 20/26) by the final follow-up visit (P < 0.0001). Postoperative complications included corneal epithelial defects (8 %), filamentary keratitis (6 %), worsening of corneal epitheliopathy (16 %), posterior capsular opacification (18 %), and cystoid macular edema (4 %). A corrected distance visual acuity of 20/30 or better was achieved in 87 % of the eyes; suboptimal CDVA improvement was attributable to severe ocular surface disease, pre-existing advanced glaucoma, and prior macular surgery. CONCLUSIONS: Phacoemulsification in patients with chronic ocular GVHD is a safe and efficacious procedure resulting in significant visual improvement. Overall, postoperative adverse events responded well to timely management.

Outcomes of Boston Keratoprosthesis Type I Implantation in Poland: A Retrospective Study on 118 Patients.

Background: Boston Keratoprosthesis Type I (BI-KPro I) is a synthetic cornea that can be used to restore vision in patients with corneal blindness. This retrospective study evaluated the outcomes of BI-KPro implantation in 118 patients. Material: The mean age of the patients was 56.76 ± 14.24 years. Indications for keratoprosthesis implantation were as follows: graft failure, 47 (39.83%); ocular burn, 38 (32.20%); neurotrophic keratopathy, 11 (9.32%), mucous membrane pemphigoid 9 (7.67%); autoimmune, 6 (5.08%); Stevens-Johnson syndrome, 4 (3.39%); and aniridia (2.54%). Methods: The surgeries were performed between March 2019 and June 2022 at a single clinical center in two locations. The postoperative visual acuity, complications, and need for additional surgical procedures were analyzed. Results: The Best Corrected Visual Acuity before surgery was 0.01 ± 0.006. After one year (V1), it was 0.30 ± 0.27; at two years (V2), it was 0.27 ± 0.26; and at three years (V3), it was 0.21 ± 0.23. The percentage of patients with visual acuity better than 0.1 on the Snellen chart was 37.29% after 1 year, 49.35% after 2 years, and 46.81% after 3 years of follow up. The most common complications were glaucoma (78 patients; 66.1%), corneal melting (22 patients; 18.6%), and retroprosthetic membranes (20 patients; 17.0%). Conclusions: The BI-KPro can significantly improve visual acuity. The worst long-term results were obtained in the group of patients with autoimmune diseases; therefore, careful consideration should be given to implanting BI-KPro in this group. The high incidence of de novo glaucoma or the progression of pre-existing glaucoma suggests the need for careful monitoring.

Estrogen genotoxicity causes preferential development of Fuchs endothelial corneal dystrophy in females.

Fuchs endothelial corneal dystrophy (FECD) is a genetically complex, age-related, female-predominant disorder characterized by loss of post-mitotic corneal endothelial cells (CEnCs). Ultraviolet-A (UVA) light has been shown to recapitulate the morphological and molecular changes seen in FECD to a greater extent in females than males, by triggering CYP1B1 upregulation in females. Herein, we investigated the mechanism of greater CEnC susceptibility to UVA in females by studying estrogen metabolism in response to UVA in the cornea. Loss of NAD(P)H quinone oxidoreductase 1 (NQO1) resulted in increased production of estrogen metabolites and mitochondrial-DNA adducts, with a higher CEnC loss in Nqo1-/- female compared to wild-type male and female mice. The CYP1B1 inhibitors, trans-2,3',4,5'-tetramethoxystilbene (TMS) and berberine, rescued CEnC loss. Injection of wild-type male mice with estrogen (E2; 17ß-estradiol) increased CEnC loss, followed by increased production of estrogen metabolites and mitochondrial DNA (mtDNA) damage, not seen in E2-treated Cyp1b1-/-male mice. This study demonstrates that the endo-degenerative phenotype is driven by estrogen metabolite-dependent CEnC loss that is exacerbated in the absence of NQO1; thus, explaining the mechanism accounting for the higher incidence of FECD in females. The mitigation of estrogen-adduct production by CYP1B1 inhibitors could serve as a novel therapeutic strategy for FECD.

Keratoprosthesis surgery as an alternative to keratoplasty.

Corneal transplant surgery after chemical or thermal burns has a very low success rate. Vision in these patients can be restored by using an artificial cornea (keratoprosthesis). In this report, we present 5 clinical cases of implanting a fresh corneal graft with Boston type 1 keratoprosthesis in patients with corneas inappropriate for standard corneal transplantation. The mean follow-up was 26.4 months (range, 12 to 36 months; SD, 13.1). The main measures of outcomes were visual acuity and keratoprosthesis stability. At least 1 year after the operation (5 eyes), vision acuity was >0.1 in 100% of the eyes and >0.4 in 50% of the eyes. Retention of the initial keratoprosthesis was 100%. The results of this study seem to be similar to those reported internationally. The anatomical and visual functions of the eyes were stable after keratoprosthesis implantation, though for a longer follow-up period, additional surgical procedures may be required.

Recurrence of Guttae and Endothelial Dysfunction After Successful Descemet Stripping Only in Fuchs Dystrophy.

PURPOSE: There are limited data about long-term durability of endothelial rejuvenation after Descemet stripping only (DSO). This study reports a case of bilaterally recurrent endothelial dysfunction and guttae formation after initially successful DSO in combination with cataract extraction (DSO-CE). METHODS: This is a retrospective case report. A 49-year-old man with Fuchs endothelial corneal dystrophy with bilateral visually significant endothelial guttae (predominantly confluent centrally) and concomitant cataract underwent DSO-CE bilaterally. Postoperative course to long-term outcome at 6 years was analyzed. RESULTS: Baseline central corneal thickness (CCT) was 568 µm in OD and 582 µm in OS. Preoperatively, both eyes had no countable central endothelial cells but good peripheral endothelial mosaic. In both eyes, the cornea clinically cleared at approximately 1 month postoperatively after DSO-CE. In short-term follow-up (OD postoperative month 6 and OS postoperative month 3), CCT was 556 µm in OD and 561 µm in OS and central endothelial cell density was 1352 cells/mm 2 in OD and 880 cells/mm 2 in OS. The patient returned to our center in postoperative year 6 OU. At this time, OU had interval formation of guttae within the descemetorhexis, with increased CCT (OD 631 µm and OS 609 µm) and decreased central endothelial cell density (OD 728 cells/mm 2 and OS 609 cells/mm 2 ). CONCLUSIONS: After DSO, progressive endothelial dysfunction with new guttae formation can occur within the descemetorhexis region of repopulated endothelium. Larger analyses with longer follow-up are needed to better characterize long-term outcomes of DSO.

Incidence and risk factors for glaucoma development and progression after corneal transplantation.

OBJECTIVE: To assess the cumulative incidence and risk factors for glaucoma development and progression within 1-2 years following corneal transplant surgery. DESIGN: Retrospective cohort study. METHODS: Patients undergoing penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), Descemet stripping endothelial keratoplasty (DSEK), Descemet membrane endothelial keratoplasty (DMEK), Boston keratoprosthesis type I (KPro) implantation, or endothelial keratoplasty (DSEK or DMEK) under previous PK (EK under previous PK) at one academic institution with at least 1 year of follow-up were included. Primary outcome measures were cumulative incidence of glaucoma development and progression after corneal transplant, in patients without and with preoperative glaucoma, respectively. Risk factors for glaucoma development and progression were also assessed. RESULTS: Four hundred and thirty-one eyes of 431 patients undergoing PK (113), DALK (17), DSEK (71), DMEK (168), KPro (35) and EK under previous PK (27) with a mean follow-up of 22.9 months were analyzed. The 1-year cumulative incidence for glaucoma development and progression was 28.0% and 17.8% in patients without and with preoperative glaucoma, respectively. In a Cox proportional hazards analysis, DSEK surgery, KPro implantation, average intraocular pressure (IOP) through follow-up and postoperative IOP spikes of ≥30 mmHg were each independently associated with glaucoma development or progression (p < 0.04 for all). CONCLUSIONS: A significant proportion of patients developed glaucoma or exhibited glaucoma progression within 1 year after corneal transplantation. Patient selection for DSEK may partly explain the higher risk for glaucoma in these patients. Postoperative IOP spikes should be minimized and may indicate the need for co-management with a glaucoma specialist.

Cultivated autologous limbal epithelial cell (CALEC) transplantation: Development of manufacturing process and clinical evaluation of feasibility and safety.

To treat unilateral limbal stem cell (LSC) deficiency, we developed cultivated autologous limbal epithelial cells (CALEC) using an innovative xenobiotic-free, serum-free, antibiotic-free, two-step manufacturing process for LSC isolation and expansion onto human amniotic membrane with rigorous quality control in a good manufacturing practices facility. Limbal biopsies were used to generate CALEC constructs, and final grafts were evaluated by noninvasive scanning microscopy and tested for viability and sterility. Cultivated cells maintained epithelial cell phenotype with colony-forming and proliferative capacities. Analysis of LSC biomarkers showed preservation of "stemness." After preclinical development, a phase 1 clinical trial enrolled five patients with unilateral LSC deficiency. Four of these patients received CALEC transplants, establishing preliminary feasibility. Clinical case histories are reported, with no primary safety events. On the basis of these results, a second recruitment phase of the trial was opened to provide longer term safety and efficacy data on more patients.

DMEK surgical training: An instructional guide on various wet-lab methods.

Descemet membrane endothelial keratoplasty (DMEK) is a partial-thickness corneal transplantation procedure that involves selective transplantation of the Descemet membrane and endothelium. DMEK offers significant advantages over other keratoplasty techniques, such as faster visual rehabilitation, better final visual acuity due to minimal optical interface effects, lower risk of allograft rejection, and less long-term dependence on topical steroids. Despite all its advantages, DMEK has been found to be more challenging than other corneal transplantation techniques, and its steep learning curve appears to be an obstacle to its widespread use and adoption by corneal surgeons worldwide. DMEK surgical training laboratories (wet labs) provide a window of opportunity for surgeons to learn, prepare, manipulate, and deliver these grafts in a risk-free environment. Wet labs are a significant learning tool, especially for those institutions that have limited tissue availability in their local centers. We provide a step-by-step guide for preparing DMEK grafts using different techniques on human and nonhuman models with instructional videos. This article should eventually help the trainees and the educators understand the requirements for performing DMEK and conducting a DMEK wet lab and develop their skills and interests from a wide variety of available techniques.

Netarsudil-associated reticular corneal epithelial edema.

PURPOSE: To describe 8 cases of reversible reticular corneal epithelial edema of the cornea that developed after use of the topical Rho-kinase inhibitor netarsudil. METHODS: This is a retrospective chart review case series of 8 patients treated with netarsudil at an academic medical center. OBSERVATIONS: Patients had predisposing corneal conditions including penetrating keratoplasty, corneal decompensation after trabeculectomy-associated endophthalmitis, congenital glaucoma with Haab striae, aphakic bullous keratopathy, history of Ahmed valve and silicone oil, and Fuchs endothelial corneal dystrophy undergoing Descemet stripping only. One patient did not have clear predisposing corneal disease other than low endothelial cell density and a history of trabeculectomy. All patients developed reticular corneal epithelial edema, which appeared as collections of moderate sized superficial epithelial bullae arranged in a reticular pattern resembling a honeycomb. Most developed these changes within weeks of initiating netarsudil, but unique to this series are 2 cases in which netarsudil was tolerated by the cornea for months before developing reticular corneal epithelial edema after diode laser cyclophotocoagulation. In cases which underwent anterior segment optical coherence tomography, the imaging demonstrated that the corneal stroma was not edematous, and the reticular corneal epithelial edema involved both host and donor corneal epithelium in cases of penetrating keratoplasty. This fully resolved in all cases upon cessation of netarsudil, and this series is the first to document resolution via a pattern in which the individual bullae become smaller and more widely spaced apart. CONCLUSION: Netarsudil can cause a reversible reticular corneal epithelial edema.

Evidence of oxidative stress in the pathogenesis of fuchs endothelial corneal dystrophy.

Fuchs endothelial corneal dystrophy (FECD) is a progressive, blinding disease characterized by corneal endothelial (CE) cell apoptosis. Corneal transplantation is the only measure currently available to restore vision in these patients. Despite the identification of some genetic factors, the pathophysiology of FECD remains unclear. In this study, we observed a decrease in the antioxidant response element-driven antioxidants in FECD corneal endothelium. We further demonstrated that nuclear factor erythroid 2-related factor 2, a transcription factor known to bind the antioxidant response element and activate antioxidant defense, is down-regulated in FECD endothelium. Importantly, we detected significantly higher levels of oxidative DNA damage and apoptosis in FECD endothelium compared with normal controls and pseudophakic bullous keratopathy (iatrogenic CE cell loss) specimens. A marker of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine, colocalized to mitochondria, indicating that the mitochondrial genome is the specific target of oxidative stress in FECD. Oxidative DNA damage was not detected in pseudophakic bullous keratopathy corneas, whereas it colocalized with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells in FECD samples. Ex vivo, oxidative stress caused characteristic morphological changes and apoptosis of CE, suggestive of findings that characterize FECD in vivo. Together, these data suggest that suboptimal nuclear factor erythroid 2-related factor 2-regulated defenses may account for oxidant-antioxidant imbalance in FECD, which in turn leads to oxidative DNA damage and apoptosis. This study provides evidence that oxidative stress plays a key role in FECD pathogenesis.