Transcription factor 4 promotes increased corneal endothelial cellular migration by altering microtubules in Fuchs endothelial corneal dystrophy.

Fuchs endothelial corneal dystrophy (FECD) is a complex corneal disease characterized by the progressive decline and morphological changes of corneal endothelial cells (CECs) that leads to corneal edema and vision loss. The most common mutation in FECD is an intronic CTG repeat expansion in transcription factor 4 (TCF4) that leads to its altered expression. Corneal endothelial wound healing occurs primarily through cell enlargement and migration, and FECD CECs have been shown to display increased migration speeds. In this study, we aim to determine whether TCF4 can promote cellular migration in FECD CECs. We generated stable CEC lines derived from FECD patients that overexpressed different TCF4 isoforms and investigated epithelial-to-mesenchymal (EMT) expression, morphological analysis and cellular migration speeds. We found that full length TCF4-B isoform overexpression promotes cellular migration in FECD CECs in an EMT-independent manner. RNA-sequencing identified several pathways including the negative regulation of microtubules, with TUBB4A (tubulin beta 4A class IVa) as the top upregulated gene. TUBB4A expression was increased in FECD ex vivo specimens, and there was altered expression of cytoskeleton proteins, tubulin and actin, compared to normal healthy donor ex vivo specimens. Additionally, there was increased acetylation and detyrosination of microtubules in FECD supporting that microtubule stability is altered in FECD and could promote cellular migration. Future studies could be aimed at investigating if targeting the cytoskeleton and microtubules would have therapeutic potential for FECD by promoting cellular migration and regeneration.

Deciphering novel TCF4-driven mechanisms underlying a common triplet repeat expansion-mediated disease.

Fuchs endothelial corneal dystrophy (FECD) is an age-related cause of vision loss, and the most common repeat expansion-mediated disease in humans characterised to date. Up to 80% of European FECD cases have been attributed to expansion of a non-coding CTG repeat element (termed CTG18.1) located within the ubiquitously expressed transcription factor encoding gene, TCF4. The non-coding nature of the repeat and the transcriptomic complexity of TCF4 have made it extremely challenging to experimentally decipher the molecular mechanisms underlying this disease. Here we comprehensively describe CTG18.1 expansion-driven molecular components of disease within primary patient-derived corneal endothelial cells (CECs), generated from a large cohort of individuals with CTG18.1-expanded (Exp+) and CTG 18.1-independent (Exp-) FECD. We employ long-read, short-read, and spatial transcriptomic techniques to interrogate expansion-specific transcriptomic biomarkers. Interrogation of long-read sequencing and alternative splicing analysis of short-read transcriptomic data together reveals the global extent of altered splicing occurring within Exp+ FECD, and unique transcripts associated with CTG18.1-expansions. Similarly, differential gene expression analysis highlights the total transcriptomic consequences of Exp+ FECD within CECs. Furthermore, differential exon usage, pathway enrichment and spatial transcriptomics reveal TCF4 isoform ratio skewing solely in Exp+ FECD with potential downstream functional consequences. Lastly, exome data from 134 Exp- FECD cases identified rare (minor allele frequency <0.005) and potentially deleterious (CADD>15) TCF4 variants in 7/134 FECD Exp- cases, suggesting that TCF4 variants independent of CTG18.1 may increase FECD risk. In summary, our study supports the hypothesis that at least two distinct pathogenic mechanisms, RNA toxicity and TCF4 isoform-specific dysregulation, both underpin the pathophysiology of FECD. We anticipate these data will inform and guide the development of translational interventions for this common triplet-repeat mediated disease.

The influence of obesity, diabetes mellitus and smoking on fuchs endothelial corneal dystrophy (FECD).

To detect environmental factors, which may be possible risk factors in the disease course of Fuchs' endothelial corneal dystrophy (FECD). Evaluation of patients with FECD registered in the FECD genetics database of the Center for Ophthalmology, University Hospital Cologne. For the evaluation, disease onset, central corneal thickness, best spectacle corrected visual acuity (BSCVA, logMAR), and modified Krachmer grading (grades 1-6) were correlated with the presence of diabetes mellitus (DM), body mass index (BMI), and smoking behavior. To put the age-related increase in Krachmer grading into perspective, a correction of grading were formed. Depending on the variables studied, differences between groups were examined by Mann-Whitney U test and chi-square test. The significance level was 5%. 403 patients with FECD were included in the analysis. The mean age of the patients was 70.0 ± 10.32 (range 28-96) years. The mean age at diagnosis of those patients was 63.1 ± 13.2 years. The female-to-male ratio was 1.46:1. Patients with a BMI > 30.0 kg/m2 developed FECD significantly earlier than patients with a BMI < 30 kg/m2, p = 0.001. Patients with DM showed significantly more often an Krachmer grade of 5, p = 0.015. Smoking had a negative effect on Krachmer grading (p = 0.024). Using the mediation analysis, the presence of DM correlated Krachmer Grade 5 (p = 0.015), and the presence of DM correlated with BMI > 30.0 kg/m2 (p = 0.012). In addition to smoking and DM our study shows for the first time that obesity may have a negative impact on the development of FECD. Whether dietary interventions and hormones can influence the development or progression of the disease needs to be investigated in future studies.

Characterization of a Novel Mouse Model for Fuchs Endothelial Corneal Dystrophy.

Purpose: Fuchs endothelial corneal dystrophy (FECD) is a progressive blinding disorder, characterized by increased corneal endothelial excrescences (guttae), corneal endothelial cell loss, and edema. These symptoms are hypothesized to be caused by changes in the extracellular matrix (ECM) and mitochondrial dysfunction in the corneal endothelium. Despite this clinical and biological relevance, a comprehensive animal model that recapitulates all the major disease characteristics is currently unavailable. In this study, we develop such a model to improve our understanding of the signaling pathways involved in the FECD progression and develop strategies for early intervention. Method: To generate a comprehensive FECD model, we generated a double mutant mouse bearing tamoxifen-inducible knockdown of Slc4a11 and the Col8a2 (Q455K) mutation. We performed optical coherence tomography (OCT) and in vivo confocal microscopy using the Heidelberg Retinal Tomography 3 - Rostock Cornea module (HRT3-RCM) on the mice at 5 weeks of age before tamoxifen feeding to establish baseline values for corneal thickness, endothelial cell density, and test for the presence of guttae. We measured these parameters again post-tamoxifen treatment at 16 weeks of age. We collected corneas at 16 weeks to perform histopathology, immunofluorescence staining for tight junctions, adherens junctions, and oxidative stress. We evaluated endothelial pump function using a lactate assay. Results: The double mutant tamoxifen-fed animals showed the presence of guttae, and displayed increased corneal thickness and decreased endothelial cell density. Endothelial cells showed altered morphology with disrupted adherens junctions and elevated reactive oxygen species (ROS). Finally, we found that stromal lactate concentrations were elevated in the double mutant mice, indicative of compromised endothelial pump function. Conclusions: Overall, this mouse model recapitulates all the important phenotypic features associated with FECD.

The surgical management of a patient with Fuchs endothelial dystrophy and cataracts.

Objective: To report the two different surgical approaches in the case of a patient with Fuchs endothelial dystrophy with low endothelial cell count and advanced cataracts. Methods: The chosen surgical approach differed between eyes, with the right eye undergoing a combined approach consisting of cataract surgery, intraocular lens implantation, and penetrating keratoplasty in 2022. One year later, for the left eye, a different approach was decided: cataract surgery followed by Descemet membrane endothelial keratoplasty (DMEK). The Descemet membrane graft was prepared by the surgeon using the liquid bubble technique. AS-OCT was used to monitor the patient before and after surgery. Results: Visual recovery was excellent for both eyes, however, visual acuity improved quickly in the left eye (DMEK), while, in the right eye (PK), the best corrected visual acuity was reached after several months post-surgery. Conclusion: Advanced stages of Fuchs dystrophy patients will most likely need corneal transplantation. Each type of corneal transplantation procedure comes with unique challenges, both intraoperative and postoperative. DMEK is a very good treatment option for patients with Fuchs endothelial dystrophy, with excellent visual recovery and good graft survival at the 10-year mark. Abbreviations: DMEK = Descemet membrane endothelial keratoplasty, PK = penetrating keratoplasty, AS-OCT = anterior segment optical coherence tomography, FECD = Fuchs endothelial corneal dystrophy, BCVA = best corrected visual acuity, US = ultrasound, CDE = cumulative dissipated energy, IOL = intraocular lens.

A multi-ancestry GWAS of Fuchs corneal dystrophy highlights the contributions of laminins, collagen, and endothelial cell regulation.

Fuchs endothelial corneal dystrophy (FECD) is a leading indication for corneal transplantation, but its molecular etiology remains poorly understood. We performed genome-wide association studies (GWAS) of FECD in the Million Veteran Program followed by multi-ancestry meta-analysis with the previous largest FECD GWAS, for a total of 3970 cases and 333,794 controls. We confirm the previous four loci, and identify eight novel loci: SSBP3, THSD7A, LAMB1, PIDD1, RORA, HS3ST3B1, LAMA5, and COL18A1. We further confirm the TCF4 locus in GWAS for admixed African and Hispanic/Latino ancestries and show an enrichment of European-ancestry haplotypes at TCF4 in FECD cases. Among the novel associations are low frequency missense variants in laminin genes LAMA5 and LAMB1 which, together with previously reported LAMC1, form laminin-511 (LM511). AlphaFold 2 protein modeling, validated through homology, suggests that mutations at LAMA5 and LAMB1 may destabilize LM511 by altering inter-domain interactions or extracellular matrix binding. Finally, phenome-wide association scans and colocalization analyses suggest that the TCF4 CTG18.1 trinucleotide repeat expansion leads to dysregulation of ion transport in the corneal endothelium and has pleiotropic effects on renal function.

Expression and Impact of Fibronectin, Tenascin-C, Osteopontin, and Type XIV Collagen in Fuchs Endothelial Corneal Dystrophy.

Purpose: Fuchs endothelial corneal dystrophy (FECD) is characterized by Descemet's membrane (DM) abnormalities, namely an increased thickness and a progressive appearance of guttae and fibrillar membranes. The goal of this study was to identify abnormal extracellular matrix (ECM) proteins expressed in FECD DMs and to evaluate their impact on cell adhesion and migration. Methods: Gene expression profiles from in vitro (GSE112039) and ex vivo (GSE74123) healthy and FECD corneal endothelial cells were analyzed to identify deregulated matrisome genes. Healthy and end-stage FECD DMs were fixed and analyzed for guttae size and height. Immunostaining of fibronectin, tenascin-C, osteopontin, and type XIV collagen was performed on ex vivo specimens, as well as on tissue-engineered corneal endothelium reconstructed using healthy and FECD cells. An analysis of ECM protein expression according to guttae and fibrillar membrane was performed using immunofluorescent staining and phase contrast microscopy. Finally, cell adhesion was evaluated on fibronectin, tenascin-C, and osteopontin, and cell migration was studied on fibronectin and tenascin-C. Results: SPP1 (osteopontin), FN1 (fibronectin), and TNC (tenascin-C) genes were upregulated in FECD ex vivo cells, and SSP1 was upregulated in both in vitro and ex vivo FECD conditions. Osteopontin, fibronectin, tenascin-C, and type XIV collagen were expressed in FECD specimens, with differences in their location. Corneal endothelial cell adhesion was not significantly affected by fibronectin or tenascin-C but was decreased by osteopontin. The combination of fibronectin and tenascin-C significantly increased cell migration. Conclusions: This study highlights new abnormal ECM components in FECD, suggests a certain chronology in their deposition, and demonstrates their impact on cell behavior.

Epithelial ingrowth in descemet membrane endothelial keratoplasty associated with vitreous loss.

BACKGROUND: Epithelial ingrowth is a rare but potentially sight-threatening complication caused by the invasion of corneal or conjunctival epithelial cells into the eye during ocular surgeries. DMEK is emerging as a widely used surgery for endothelial keratoplasty with its improved safety profile. We describe a case of epithelial ingrowth in the graft-host interface after uneventful DMEK associated with vitreous prolapse in the anterior chamber. CASE PRESENTATION: An 81-year-old female with Fuchs endothelial dystrophy underwent DMEK for corneal decompensation following cataract surgery. During the DMEK procedure, vitreous prolapse was observed around the intraocular lens (IOL). Her early postoperative course was unremarkable, but a dense paracentral interface opacity was observed during the 3-month follow-up. The area of epithelial ingrowth was imaged with optical coherence tomography (OCT) as a uniform nodule with a discrete increase in interface hyperreflectivity. A low-energy YAG laser was applied to remove the opacity. She maintained good vision and clear cornea without reoccurrence after treatment. CONCLUSIONS: We propose that, in addition to the introduction of epithelial cells during surgery, vitreous retention in the anterior chamber may be a risk factor by providing a scaffold that potentially aggravates epithelial ingrowth in DMEK. Our case demonstrated that early YAG intervention may disrupt interface epithelial cell growth, and the transmitted laser energy may fragment the scaffold vitreous noninvasively.

[Outcomes of hemi-Descemet membrane endothelial keratoplasty and phacoemulsification for the treatment of primary Fuchs' endothelial corneal dystrophy combined with cataract]. / Rezul'taty transplantatsii destsemetovoi membrany s endoteliem i fakoemul'sifikatsii pri pervichnoi endotelial'noi distrofii rogovitsy Fuksa, sochetannoi s kataraktoi.

PURPOSE: This study evaluates the long-term results of surgical treatment of patients with Fuchs' endothelial corneal dystrophy and cataract. MATERIAL AND METHODS: The study included 24 patients (24 eyes) with primary Fuchs' endothelial corneal dystrophy and cataract, who underwent cataract phacoemulsification with IOL implantation and of Descemet's membrane endothelial keratoplasty with a semicircular graft (hemi-DMEK). The effect of treatment was assessed by best corrected visual acuity (BCVA), central corneal thickness (CCT) and endothelial cell density (ECD). RESULTS: In total, surgical treatment involved 14 donor corneas that were divided in half during the preparation and isolation of the Descemet's membrane (DM). By month 12 after the surgery an increase in visual functions and graft transparency were observed in 23 patients (23 eyes) out of 24. Repeated keratoplasty was required in one case due to fibrosis of the posterior layers of recipient's corneal stroma. At 12 months postoperatively, the study group showed an increase in BCVA from 0.16±0.1 to 0.75±20, a decrease in CCT from 650.9±4.5 µm to 519.6±43.9, and a decreased in ECD from 2850.5±84.7 cells/mm2 up to 1285.5±277.2 cells/mm2. Thus, the loss of endothelial cells at one year after surgery amounted to 54.9%. CONCLUSIONS: The developed method for transplantation of a semicircular DM fragment provides a tissue-saving approach to endothelial keratoplasty, and considering the high percentage of transparent engraftment of grafts and complete visual rehabilitation, it can be recommended in the treatment of patients with cataract and Fuchs' endothelial corneal dystrophy.

Double trouble in DMEK surgery: Learning experience and review of the literature.

PURPOSE: To report a challenging Descemet Membrane Endothelial Keratoplasty (DMEK) case, complicated by intraoperative aqueous misdirection and spontaneous anterior chamber fibrin reaction. METHODS: A 70-year-old female affected by corneal edema due to Fuchs endothelial dystrophy underwent a triple procedure (cataract extraction - IOL implantation - DMEK surgery) in her left eye. This report illustrates the management of the intraoperative complications of aqueous misdirection syndrome and anterior chamber fibrin reaction. RESULTS: Despite the optimal management of the posterior pressure and the thorough removal of the fibrinous reaction during the case, the DMEK graft was not completely unfolded and centred at the end of the surgical procedure. Nonetheless, the patient showed good long-term anatomical and functional recovery: at the last follow-up (2 years after surgery), central corneal thickness was 526 µm with a best corrected visual acuity of 20/25 and an endothelial cell density of 1112 cell/mm2. CONCLUSION: Early recognition and prompt management of intraoperative aqueous misdirection syndrome and anterior chamber fibrin reaction during DMEK surgery is essential to ensure good functional and anatomical outcomes.

Long noncoding RNA ZFAS1: A novel anti-apoptotic target in Fuchs endothelial corneal dystrophy.

Fuchs endothelial corneal dystrophy (FECD) is the leading cause of endothelial keratoplasty without efficacious drug treatment. Recent studies have emphasized the involvement of epigenetic regulation in FECD development. Long non-coding RNAs (lncRNAs) are recognized as crucial epigenetic regulators in diverse cellular processes and ocular diseases. In this study, we revealed the expression patterns of lncRNAs using high-throughput sequencing technology in FECD mouse model, and identified 979 significantly dysregulated lncRNAs. By comparing the data from FECD human cell model, we obtained a series of homologous lncRNAs with similar expression patterns, and revealed that these homologous lncRNAs were enriched in FECD related biological functions, with apoptosis (mmu04210) showing the highest enrichment score. In addition, we investigated the role of lncRNA zinc finger antisense 1 (ZFAS1) in apoptotic process. This study would broaden our understanding of epigenetic regulation in FECD development, and provide potential anti-apoptotic targets for FECD therapy.

One-year Outcomes of Ultrathin Descemet Stripping Automated Endothelial Keratoplasty Combined with Cataract Surgery in the Korean Population.

PURPOSE: To evaluate the refractive outcomes after ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) combined with phacoemulsification and intraocular lens implantation (triple procedure) in the South Korean population. METHODS: This retrospective observational study included 37 eyes of 36 patients who underwent the UT-DSAEK triple procedure between 2012 and 2021 in a single tertiary hospital. Preoperative and postoperative refractive outcomes and endothelial parameters at 1, 3, 6, and 12 months were observed. RESULTS: At the final postoperative 12-month period, the average best-corrected visual acuity was 0.4 ± 0.5 in logarithm of the minimum angle of resolution. The mean endothelial cell density at 12 months was 1,841.92 ± 731.24 cells/mm2, indicating no significant endothelial cell loss compared to the baseline (p = 0.128). The mean postoperative central corneal thickness at 12 months was 597.41 ± 86.26 µm. The postoperative mean absolute error at 12 months was 0.96 ± 0.89 diopters (D) and mean error was 0.89 ± 0.97 D. CONCLUSIONS: The results of our South Korean cohort study on UT-DSAEK triple surgery showed favorable and safe outcomes. Regardless of graft thickness, it should be noted that a hyperopic shift of 1.00 to 2.00 D needs to be considered in the case of UT-DSAEK triple surgery.

Fuchs endothelial corneal dystrophy: an updated review.

PURPOSE: The present review will summarize FECD-associated genes and pathophysiology, diagnosis, current  therapeutic approaches, and future treatment perspectives. METHODS: Literature review. RESULTS: Fuchs' endothelial corneal dystrophy (FECD) is the most common bilateral corneal dystrophy and accounts for one-third of all corneal transplants performed in the US. FECD is caused by a combination of genetic and non-heritable factors, and there are two types: early-onset FECD, which affects individuals from an early age and is usually more severe, and late-onset FECD, which is more common and typically manifests around the age of 40. The hallmark findings of FECD include progressive loss of corneal endothelial cells and the formation of focal excrescences (guttae) on the Descemet membrane. These pathophysiological changes result in progressive endothelial dysfunction, leading to a decrease in visual acuity and blindness in later stages. The present review will summarize FECD-associated genes and pathophysiology, diagnosis, current therapeutic approaches, and future treatment perspectives. CONCLUSION: With the characterization and understanding of FECD-related genes and ongoing research into regenerative therapies for corneal endothelium, we can hope to see more significant improvements in the future in the management and care of the disease.

Squishy matters - Corneal mechanobiology in health and disease.

The cornea, as a dynamic and responsive tissue, constantly interacts with mechanical forces in order to maintain its structural integrity, barrier function, transparency and refractive power. Cells within the cornea sense and respond to various mechanical forces that fundamentally regulate their morphology and fate in development, homeostasis and pathophysiology. Corneal cells also dynamically regulate their extracellular matrix (ECM) with ensuing cell-ECM crosstalk as the matrix serves as a dynamic signaling reservoir providing biophysical and biochemical cues to corneal cells. Here we provide an overview of mechanotransduction signaling pathways then delve into the recent advances in corneal mechanobiology, focusing on the interplay between mechanical forces and responses of the corneal epithelial, stromal, and endothelial cells. We also identify species-specific differences in corneal biomechanics and mechanotransduction to facilitate identification of optimal animal models to study corneal wound healing, disease, and novel therapeutic interventions. Finally, we identify key knowledge gaps and therapeutic opportunities in corneal mechanobiology that are pressing for the research community to address especially pertinent within the domains of limbal stem cell deficiency, keratoconus and Fuchs' endothelial corneal dystrophy. By furthering our understanding corneal mechanobiology, we can contextualize discoveries regarding corneal diseases as well as innovative treatments for them.

Targeting the NRF2 pathway: A promising approach for corneal endothelial dysfunction.

Maintaining corneal endothelial function is required for vision, and corneal endothelial dysfunction is a major cause of visual deficits and blindness worldwide. To date there has been a dearth of innovation for therapeutics targeting the corneal endothelium. However, recent advances in understanding the role of oxidative stress and mitochondrial dysfunction have revealed potential avenues for the development of new therapies. This review summarizes recent developments in elucidating the role of the NRF2 pathway in corneal endothelial health and disease, focusing specifically on Fuchs' endothelial corneal dystrophy and the loss of corneal endothelial cells associated with cataract surgery. The pro-mitochondrial and antioxidant phenotype elicited by NRF2 activation offers a promising opportunity for new therapeutics for the diseased corneal endothelium.

Descemet Endothelial Thickness Comparison Trial 1 (DETECT 1): outcome masked, placebo-controlled trial comparing two types of corneal transplant surgeries and effect of rho kinase inhibitors on endothelial cell loss protocol.

BACKGROUND: It remains uncertain which endothelial keratoplasty (EK) technique yields the best outcomes while maintaining safety, particularly in eyes with coexisting ocular conditions. Moreover, the impact of endothelial cell loss (ECL) on long-term graft survival requires further investigation. Adjuvant ripasudil, a rho kinase inhibitor, may address the challenge of ECL in corneal transplantation. This paper presents the protocol for the Descemet Endothelial Thickness Comparison Trial 1 (DETECT 1), a multicentre, outcome-masked, randomised, placebo-controlled, four-arm clinical trial. METHODS: A total of 160 eligible patients with endothelial dysfunction will be enrolled from five participating sites in the USA. The patients will be randomly assigned in a 2×2 factorial design to one of the following treatment groups: group 1-ultrathin Descemet stripping endothelial keratoplasty (UT-DSAEK) plus topical ripasudil 0.4%; group 2-UT-DSAEK plus topical placebo; group 3-Descemet membrane endothelial keratoplasty (DMEK) plus topical ripasudil 0.4% and group 4-DMEK plus topical placebo. Primary outcomes include the best spectacle-corrected visual acuity at 12 months and ECL at 12 months. Secondary outcomes include visual acuity at different time points, vision-related quality of life, endothelial cell morphology and cost-effectiveness. RESULTS: The study outcomes will be analysed using mixed effects linear regression models, taking into account the treatment arms and relevant covariates. Adverse events, including rebubble procedures, graft failure and graft rejection, will be documented and analysed using appropriate statistical methods. CONCLUSION: DETECT I aims to provide evidence on the comparative effectiveness of UT-DSAEK and DMEK, as well as the potential benefits of adjuvant topical ripasudil in reducing ECL. The results of this trial will contribute to optimising corneal transplantation techniques and improving long-term graft survival, while also exploring the cost-effectiveness of these interventions. Dissemination of findings through peer-reviewed publications and national/international meetings will facilitate knowledge translation and guide clinical practice in the field of corneal transplantation. ETHICS AND DISSEMINATION: A data and safety monitoring committee (DSMC) has been empaneled by the NEI.All study protocols will be subject to review and approval by WCG IRB as the single IRB of record.This study will comply with the National Institute of Health (NIH) Data Sharing Policy and Policy on the Dissemination of NIH-Funded Clinical Trial Information and the Clinical Trials Registration and Results Information Submission rule. Data from the trial will be made available on reasonable request.

Investigation of the functional impact of CHED- and FECD4-associated SLC4A11 mutations in human corneal endothelial cells.

Mutations in the solute linked carrier family 4 member 11 (SLC4A11) gene are associated with congenital hereditary endothelial dystrophy (CHED) and Fuchs corneal endothelial dystrophy type 4 (FECD4), both characterized by corneal endothelial cell (CEnC) dysfunction and/or cell loss leading to corneal edema and visual impairment. In this study, we characterize the impact of CHED-/FECD4-associated SLC4A11 mutations on CEnC function and SLC4A11 protein localization by generating and comparing human CEnC (hCEnC) lines expressing wild type SLC4A11 (SLC4A11WT) or mutant SLC4A11 harboring CHED-/FECD4-associated SLC4A11 mutations (SLC4A11MU). SLC4A11WT and SLC4A11MU hCEnC lines were generated to express either SLC4A11 variant 2 (V2WT and V2MU) or variant 3 (V3WT and V3MU), the two major variants expressed in ex vivo hCEnC. Functional assays were performed to assess cell barrier, proliferation, viability, migration, and NH3-induced membrane conductance. We demonstrate SLC4A11-/- and SLC4A11MU hCEnC lines exhibited increased migration rates, altered proliferation and decreased cell viability compared to SLC4A11WT hCEnC. Additionally, SLC4A11-/- hCEnC demonstrated decreased cell-substrate adhesion and membrane capacitances compared to SLC4A11WT hCEnC. Induction with 10mM NH4Cl led SLC4A11WT hCEnC to depolarize; conversely, SLC4A11-/- hCEnC hyperpolarized and the majority of SLC4A11MU hCEnC either hyperpolarized or had minimal membrane potential changes following NH4Cl induction. Immunostaining of primary hCEnC and SLC4A11WT hCEnC lines for SLC4A11 demonstrated predominately plasma membrane staining with poor or partial colocalization with mitochondrial marker COX4 within a subset of punctate subcellular structures. Overall, our findings suggest CHED-associated SLC4A11 mutations likely lead to hCEnC dysfunction, and ultimately CHED, by interfering with cell migration, proliferation, viability, membrane conductance, barrier function, and/or cell surface localization of the SLC4A11 protein in hCEnC. Additionally, based on their similar subcellular localization and exhibiting similar cell functional profiles, protein isoforms encoded by SLC4A11 variant 2 and variant 3 likely have highly overlapping functional roles in hCEnC.

Corneal Guttae After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: The aim of this study was to report on the occurrence of corneal guttae after Descemet membrane endothelial keratoplasty (DMEK). METHODS: In this retrospective case series, 13 eyes of 13 patients who underwent DMEK at 2 tertiary referral centers between 2007 and 2021 (average available follow-up 73 ± 52 months, range 18-174 months) and showed corneal guttae during postoperative examinations were included. Eye bank images were retrospectively reviewed. RESULTS: Occurrence of guttae was observed by specular microscopy in 13 eyes. In 11 cases, presence of guttae was confirmed by confocal microscopy and in 1 case by histology. Five eyes showed an increase in guttae density during the postoperative course. Surgery indications were Fuchs endothelial corneal dystrophy (n = 11), pseudophakic bullous keratopathy (n = 1), and DMEK graft failure after allograft rejection (n = 1); the latter eye had shown no signs of guttae after primary DMEK. Two eyes with guttae required a repeat DMEK due to graft failure. At the last available follow-up, all 11 remaining eyes had clear corneas and 10 eyes had a best-corrected visual acuity of ≥0.9 (decimal). During donor cornea processing in the eye bank, no guttae were observed on the donor tissue. CONCLUSIONS: Corneal guttae can occur after DMEK including in eyes operated for indications other than Fuchs endothelial corneal dystrophy and most likely guttae were present on the donor graft but were not detectable by routine slit-lamp and light microscopy evaluation in the eye bank. Postoperative guttae density varies among patients and especially small isolated guttae do not seem to affect clinical outcomes.