Fuchs Endothelial Corneal Dystrophy Patients Research Articles

Lower Fractions of TCF4 Transcripts Spanning over the CTG18.1 Trinucleotide Repeat in Human Corneal Endothelium.

Fuchs’ endothelial corneal dystrophy (FECD) is a bilateral disease of the cornea caused by gradual loss of corneal endothelial cells. Late-onset FECD is strongly associated with the CTG18.1 trinucleotide repeat expansion in the Transcription Factor 4 gene (TCF4), which forms RNA nuclear foci in corneal endothelial cells. To date, 46 RefSeq transcripts of TCF4 are annotated by the National Center of Biotechnology information (NCBI), however the effect of the CTG18.1 expansion on expression of alternative TCF4 transcripts is not completely understood. To investigate this, we used droplet digital PCR for quantification of TCF4 transcripts spanning over the CTG18.1 and transcripts with transcription start sites immediately downstream of the CTG18.1. TCF4 expression was analysed in corneal endothelium and in whole blood of FECD patients with and without CTG18.1 expansion, in non-FECD controls without CTG18.1 expansion, and in five additional control tissues. Subtle changes in transcription levels in groups of TCF4 transcripts were detected. In corneal endothelium, we found a lower fraction of transcripts spanning over the CTG18.1 tract compared to all other tissues investigated.

Comparison of TCF4 repeat expansion length in corneal endothelium and leukocytes of patients with Fuchs endothelial corneal dystrophy.

Expansion of CTG trinucleotide repeats (TNR) in the transcription factor 4 (TCF4) gene is highly associated with Fuchs Endothelial Corneal Dystrophy (FECD). Due to limitations in the availability of DNA from diseased corneal endothelium, sizing of CTG repeats in FECD patients has typically been determined using DNA samples isolated from peripheral blood leukocytes. However, it is non-feasible to extract enough DNA from surgically isolated FECD corneal endothelial tissue to determine repeat length based on current technology. To circumvent this issue, total RNA was isolated from FECD corneal endothelium and sequenced using long-read sequencing. Southern blotting of DNA samples isolated from primary cultures of corneal endothelium from these same affected individuals was also assessed. Both long read sequencing and Southern blot analysis showed significantly longer CTG TNR expansion (>1000 repeats) in the corneal endothelium from FECD patients than those characterized in leukocytes from the same individuals (<90 repeats). Our findings suggest that the TCF4 CTG repeat expansions in the FECD corneal endothelium are much longer than those found in leukocytes.

Automated Image Segmentation of the Corneal Endothelium in Patients With Fuchs Dystrophy.

PurposeTo perform segmentation of specular microscopy (SM) images of the corneal endothelium for comparing average perimeter length (APL) between Fuchs endothelial corneal dystrophy (FECD) patients and healthy subjects.MethodsA retrospective review of clinical records of FECD patients and those with healthy endothelium was carried out to collect images of the endothelium. The images were segmented by modified U-Net, a deep learning architecture, followed by the Watershed algorithm to resolve merged cell borders (<5%). The segmented images were analyzed for endothelial cell density (ECDUW) and APL.ResultsThe combination of the U-Net and Watershed algorithm, referred to as the UW approach, enabled a complete segmentation of the endothelium. In healthy, ECDUW was close to estimates by SM and manual segmentation (31 subjects; P > 0.1). However, in FECD, ECDUW was closer to estimates by manual segmentation but not by SM (27 patients; P < 0.001). ECDUW in FECD (2547 ± 499 cells/mm2; 60 patients) was smaller compared to that in the healthy (2713 ± 401 cells/mm2; 70 subjects) (P < 0.001). APL in the healthy was 66.87 ± 7.68 µm/cell (70 subjects), but it increased with %Guttae in FECD (56.60–195.30 µm/cell; 60 patients) (P < 0.0001).ConclusionsThe UW approach is precise for the segmentation of SM images from the healthy and FECD. Our analysis has revealed that APL increases with %Guttae.Translational RelevanceThe average perimeter length of the corneal endothelium, which represents the length of the paracellular pathway for fluid flux into the stroma, is increased in Fuchs dystrophy.

Chord Mu (µ) and Chord Alpha (α) Length Changes in Fuchs Endothelial Corneal Dystrophy before and after Descemet Membrane Endothelial Keratoplasty (DMEK) Surgery.

This paper will evaluate chord mu and alpha length in patients with Fuchs endothelial corneal dystrophy (FECD) and its changes following Descemet membrane endothelial keratoplasty (DMEK). Patients with FECD that underwent DMEK surgery were included in this retrospective study. Scheimpflug Tomography was carried out in order to calculate chord mu and chord alpha lengths prior to surgery and at 3 and 12 months postoperative. This study included 27 eyes from 27 patients. Significant changes in chord mu were observed within the first three months (from 0.47 ± 0.32 to 0.29 ± 0.21 mm, p < 0.01) and remained stable 12 months postoperative (0.30 ± 0.21 mm, p > 0.05). However, chord alpha remained stable throughout the 12 months post surgery (from 0.53 ± 0.19 to 0.49 ± 0.14 mm, p > 0.05). In addition to the pupillary center distance from the corneal center (from 0.35 ± 0.25 to 0.34 ± 0.20 mm, p > 0.05) also remain stable. In FECD patients undergoing DMEK surgery, chord mu length decreased, and chord alpha length remained stable after 12 months of follow-up.

TCF4 trinucleotide repeat expansion in Swedish cases with Fuchs' endothelial corneal dystrophy.

Fuchs' endothelial corneal dystrophy (FECD) has been considered a genetically heterogeneous disease but is increasingly associated with the transcription factor 4 (TCF4) gene. This study investigates the prevalence of the cytosine-thymine-guanine (CTG)n repeat expansion in TCF4 among FECD patients in northern Sweden coupled to the phenotype. Blood samples were collected from 85 FECD cases at different stages. Short tandem repeat PCR and triplet repeat-primed PCR were applied in order to determine TCF4 (CTG)n genotype. A (CTG)n repeat expansion (n > 50) in TCF4 was identified in 76 of 85 FECD cases (89.4%) and in four of 102 controls (3.9%). The median (CTG)n repeat length was 81 (IQR 39.3) in mild FECD and 87 (IQR 13.0) in severe FECD (p = 0.01). A higher number of (CTG)n repeats in an expanded TCF4 allele increased the probability of severe FECD. Other ocular surgery was overrepresented in FECD cases without a (CTG)n repeat expansion (44.4%, n = 4) compared with 3.9% (n = 3) in FECD cases with an (CTG)n repeat expansion (p < 0.001). In northern Sweden, the FECD phenotype is associated with (CTG)n expansion in the TCF4 gene, with nearly 90% of patients being hetero- or homozygous for (CTG)n expansion over 50 repeats. Furthermore, the severity of FECD was associated with the repeat length in the TCF4 gene. Ocular surgery might act as an environmental factor explaining the clinical disease in FECD without a repeat expansion in TCF4.

Impact of TCF4 Repeat Number on Resolution of Corneal Edema after Descemet's Stripping Only in Fuchs Dystrophy: A Pilot Study.

Purpose: To investigate whether Fuchs endothelial corneal dystrophy (FECD) genotype, specifically transcription factor 4 (TCF4) CTG triplet repeat “load” predicts time to clearance following Descemet’s Stripping Only (DSO). Methods: This prospective, interventional trial was conducted on consecutive FECD patients undergoing DSO. Genetic analysis using patients’ saliva was performed to assess the extent of CTG expansion using short tandem repeat analysis, corroborated gel electrophoresis and Sanger sequencing. Polymerase chain reaction and bidirectional Sanger sequencing was undertaken. Partial least square regression and logistic regression modelling was used to evaluate the predictive power of TCF4 repeats on corneal clearance. Results: Of 11 eyes of 11 patients, 8 showed complete corneal clearance. For these 8 patients, mean TCF4 allele repeat was 24.8 (SD: 23.7, range: 11–63) and 63.4 (SD: 30.3; range: 11–97), respectively. In total, 9/11 (81.8%) had expanded CTG repeats (>40) in one allele. In cases with an allele repeat ≥80, there was a significantly increased risk of corneal non-clearance (odds ratio 18.2, p = 0.009). Conclusion: Whilst it was not possible to predict time to corneal clearance based on CTG repeats, there is a significant correlation between allele repeats and achievement of corneal clearance.

Refractive Outcomes in Fuchs' Endothelial Corneal Dystrophy: Conventional and Femtosecond Laser-Assisted Cataract Surgery.

PurposeTo investigate the refractive outcomes of eyes with Fuchs’ endothelial corneal dystrophy (FECD) following phacoemulsification.MethodsThis is a retrospective chart review of patients with FECD who underwent phacoemulsification. Manifest refraction at the early postoperative period (1–6 weeks) and late postoperative period (3–12 months) was collected. The spherical equivalent (SE) and variance of SE from target in diopters (D) were analyzed.ResultsA total of 219 eyes from 175 FECD patients (73 FLACS, 146 conventional phacoemulsification) were included. In the early postoperative period, when comparing variance from intended target, 62% (n=126) had a SE variance of ≤0.5 D, 22% (n=44) >0.5 D and ≤1 D, and 17% (n=34) >1 D. In the late postoperative period, 62% (n=85) had a SE variance of ≤0.5 D, 19% (n=26) >0.5 D and ≤1 D, and 20% (n=27) >1 D. There was no difference in the variance of SE comparing FLACS versus conventional phacoemulsification in either the early postoperative period (p=0.78) or the late postoperative period (p=0.29).ConclusionPatients with mild-to-moderate FECD had favorable refractive outcomes with phacoemulsification. There was no difference in refractive outcomes in eyes with FECD between the group that underwent FLACS versus the group that underwent conventional phacoemulsification.

Mitochondrial Dysfunction and Mitophagy in Fuchs Endothelial Corneal Dystrophy.

Fuchs endothelial corneal dystrophy (FECD) is a genetically complex, heterogenous, age-related degenerative disease of corneal endothelial cells (CEnCs), occurring in the fifth decade of life with a higher incidence in females. It is characterized by extracellular matrix (ECM) protein deposition called corneal guttae, causing light glare and visual complaints in patients. Corneal transplantation is the only treatment option for FECD patients, which imposes a substantial socioeconomic burden. In FECD, CEnCs exhibit stress-induced senescence, oxidative stress, DNA damage, heightened reactive oxygen species (ROS) production, mitochondrial damage, and dysfunction as well as sustained endoplasmic reticulum (ER) stress. Among all of these, mitochondrial dysfunction involving altered mitochondrial bioenergetics and dynamics plays a critical role in FECD pathogenesis. Extreme stress initiates mitochondrial damage, leading to activation of autophagy, which involves clearance of damaged mitochondria called auto(mito)phagy. In this review, we discuss the role of mitochondrial dysfunction and mitophagy in FECD. This will provide insights into a novel mechanism of mitophagy in post-mitotic ocular cell loss and help us explore the potential treatment options for FECD.

Incidence and Risk Factors of Corneal Endothelial Failure after Phacoemulsification in Patients with Fuchs Endothelial Corneal Dystrophy: A 13-Year Retrospective Cohort.

ObjectiveTo evaluate the incidence of corneal endothelial failure (CEF) and determine the risk factors of developing CEF after phacoemulsification in patients with Fuchs endothelial corneal dystrophy (FECD).MethodsA retrospective chart review of 2873 patients who underwent phacoemulsification with intraocular lens (IOL) implantation was conducted at Ramathibodi Hospital, Bangkok, Thailand from January 2007 to December 2019. Patient baseline characteristics, underlying diseases, levels of nuclear cataract, pre-operative specular microscopic parameters, intraoperative information (cumulative dissipated energy [CDE], mode of phacoemulsification, and complications), and occurrence of CEF were collected. Data were analyzed using Kaplan–Meier (KM) method and Cox proportional hazard model.ResultsNinety-four patients diagnosed with FECD at follow-up time of more than 6 months were included for analysis. Mean age was 70.3 ± 7.7 years with female predominance (81.91%). Median follow-up time was 3.2 years. Nine (9.57%) patients developed CEF during follow-up period. The overall incidence rate of CEF after phacoemulsification was 26 per 1000 person years (95% confidence interval [CI]; 14 to 49 per 1000 person years). Only intraoperative complications showed significant association with CEF at hazard ratio (HR) of 6.03 (95% CI 1.50 to 26.50). No significant association was found among age, gender, underlying diseases, level of nuclear sclerosis and pre-operative specular microscopic parameters.ConclusionIntraoperative complications should be considered as an important risk factor for developing post-operative CEF in FECD patients. Apart from assessing pre-operative parameters, surgeons should also consider the possibility of and try to avoid any intra-operative complications, which could potentially result in CEF after phacoemulsification for each individual patient.

A Close Look at the Clinical Efficacy of Rho-Associated Protein Kinase Inhibitor Eye Drops for Fuchs Endothelial Corneal Dystrophy.

:The current understanding on the clinical efficacy of Rho-associated protein kinase (ROCK) inhibitor for treating Fuchs endothelial corneal dystrophy is summarized to clarify whether the “off-label” ROCK-inhibitor eye-drop application are appropriate. ROCK-inhibitor eye drops may eventually be deemed a cutting-edge therapy for Fuchs endothelial corneal dystrophy patients with acute corneal endothelial defect.

New evidences suggesting that the central endothelium of Fuchs Endothelial Corneal Dystrophy (FECD) presents features of peripheral endothelium

AbstractPurposeMost recent studies about FECD highlighted its complex and heterogeneous genetic background. Yet, the sequence of cellular mechanisms leading to the formation of Descemet excrescents (Guttae), endothelial cell (EC) death and loss of pumping functions remains poorly understood.AimTo present new phenotypic characteristics of ECs observed in late onset FCED, opening new perspectives in understanding its pathogenesis.MethodsThirty corneal central buttons were collected from FECD patients during graft. They were compared with fresh normal corneas (body donation to Sciences), and with 10 whole corneas with early stage of FECD (discarded from our eye bank). The morphology of ECs and of guttae, the expression of EC markers, of stem cell markers, of proliferation marker and of extracellular matrix was studied using the immunostaining of flat mount of corneas.ResultsCentral ECs of FECD specimens and extreme peripheral ECs of fresh corneas shared common features: weaker expression of the usual CE markers (Na/K ATPase, ZO‐1, COXIV, CD166, N‐cadherin), expression of mesenchymal stem cells markers (nestin, c‐Myc, CD44), presence of proliferating cells (Ki67), presence of numerous dead cells (Ethidium), numerous cells containing pigments, isolated and confluent guttae, thicker Descemet membrane (DM), and localization of collagen I, IV, V and VIII. In corneas with early stages of FECD, the peripheral radial rows of EC and Descemet striae normally observed in healthy corneas were here significantly enlarged.ConclusionsThese new features of ECs and DM suggest that central ECs of FECD acquire or retain characteristics of peripheral ECs of healthy corneas, corresponding to less differentiated cells. We, therefore, suggest a new physiopathology mechanism involving the abnormal dedifferentiation of ECs in the centre of the cornea, resulting in the slow formation of the plaque‐like endothelial structure, typical of FCED.

Potential Functional Restoration of Corneal Endothelial Cells in Fuchs Endothelial Corneal Dystrophy by ROCK Inhibitor (Ripasudil)

Rho-associated kinase (ROCK) inhibitors have been successfully used as a rescue strategy in eyes that failed to clear after descemetorhexis without endothelial graft for treatment of Fuchs endothelial corneal dystrophy (FECD). The functional mechanisms by which ROCK inhibitors modulate corneal endothelial cell regeneration in FECD patients have, however, not been clarified. Here, we analyzed the effect of the ROCK inhibitor ripasudil on corneal endothelial cells of FECD patients and normal donors using exvivo tissue and invitro cellular models. Experimental study: laboratory investigation. This institutional study used endothelial cell-Descemet membrane lamellae from FECD patients (n= 450) undergoing Descemet membrane endothelial keratoplasty (FECD exvivo model), normal research-grade donor corneas (n= 30) after scraping off central endothelial cells (exvivo wound healing model), normal donor corneas (n= 20) without endothelial injury, and immortalized cell lines (n= 3) generated from FECD patients (FECD invitro model). Descemet membrane lamellae were dissected into halves and incubated for 24-72 hours in storage medium with or without a single dose of 30μM ripasudil. The effects of ripasudil on expression of genes and proteins related to endothelial cell proliferation, migration, functionality, and endothelial-to-mesenchymal transition were analyzed and complemented by functional assays on FECD cell lines. A single dose of ripasudil induced significant upregulation of genes and proteins related to cell cycle progression, cell-matrix adhesion and migration, as well as endothelial barrier and pump function up to 72 hours, whereas classical markers of endothelial-to-mesenchymal transition were downregulated in both FECD and normal specimens compared to unstimulated controls exvivo. In addition to stimulation of proliferation and migration, ripasudil-induced changes in expression of functional signature genes could be also verified in FECD cell lines invitro. These data support the concept that inhibition of ROCK signaling represents a potent tool in regenerative therapies in FECD patients through reactivation of cell proliferation and migration as well as restoration of endothelial pump and barrier function without inducing adverse phenotypic changes.

The Fuchs corneal dystrophy-associated CTG repeat expansion in the TCF4 gene affects transcription from its alternative promoters

The CTG trinucleotide repeat (TNR) expansion in Transcription factor 4 (TCF4) intron 3 is the main cause of Fuchs’ endothelial corneal dystrophy (FECD) and may confer an increased risk of developing bipolar disorder (BD). Usage of alternative 5′ exons for transcribing the human TCF4 gene results in numerous TCF4 transcripts which encode for at least 18 N-terminally different protein isoforms that vary in their function and transactivation capability. Here we studied the TCF4 region containing the CTG TNR and characterized the transcription initiation sites of the nearby downstream 5′ exons 4a, 4b and 4c. We demonstrate that these exons are linked to alternative promoters and show that the CTG TNR expansion decreases the activity of the nearby downstream TCF4 promoters in primary cultured neurons. We confirm this finding using two RNA sequencing (RNA-seq) datasets of corneal endothelium from FECD patients with expanded CTG TNR in the TCF4 gene. Furthermore, we report an increase in the expression of various other TCF4 transcripts in FECD, possibly indicating a compensatory mechanism. We conclude that the CTG TNR affects TCF4 expression in a transcript-specific manner both in neurons and in the cornea.

Fourier Analysis on Regular and Irregular Astigmatism of Anterior and Posterior Corneal Surfaces in Fuchs Endothelial Corneal Dystrophy

To conduct Fourier analysis on regular and irregular astigmatism of the anterior and posterior corneal surfaces using anterior segment optical coherence tomography in patients with Fuchs endothelial corneal dystrophy (FECD) DESIGN: Observational case series. This study included 75 eyes of 43 FECD patients and 34 eyes of 34 healthy subjects in Osaka University Hospital. Corneal dioptric data from the central 6-mm zone of the anterior and posterior corneal surface were expanded into spherical, regular astigmatism, asymmetry, and higher-order irregularity components using Fourier analysis. We analyzed the association between each component and modified Krachmer grade. There were significant differences in regular astigmatism, asymmetry, and higher-order irregularity components of the anterior corneal surface, and spherical, regular astigmatism, asymmetry, and higher-order irregularity components of the posterior corneal surface among modified Krachmer grades (P= .036, <.001, <.001, <.001, <.001, <.001, and <.001, respectively). Asymmetry component of the anterior and posterior corneal surfaces gradually increased with FECD progression. Higher-order irregularity components of the anterior and posterior corneal surfaces drastically increased in Grade 6. Many eyes had an axis of 0°-180° for the asymmetry component of the anterior surface and 180°-360° for that of the posterior surface. Patients with severe FECD had a larger amount of asymmetry and higher-order irregularity components of the anterior and posterior corneal surfaces. Patients with FECD up to Grade 5 were characterized by anterior and posterior flattening in the inferior cornea, and those with Grade 6 showed irregularity in the anterior and posterior corneal surfaces.

Automated Clinical Assessment of Corneal Guttae in Fuchs Endothelial Corneal Dystrophy

To describe the validation and implementation of an automated system for the detection and quantification of guttae in Fuchs endothelial corneal dystrophy (FECD). Observational reliability study. Patients with FECD underwent retroillumination corneal photography, followed by determination of the distributions and sizes of corneal guttae by an automated image analysis algorithm. Performance of the automated system was assessed via (1) validation against manual guttae segmentation, (2) reproducibility studies to ensure consistency, and (3) evaluation for agreement with the Krachmer scale. It was then deployed to perform large-scale guttae assessment with anatomic subregion analysis in a batch of 40 eyes. Compared to manual segmentation, the automated system was reasonably accurate in identifying the correct number of guttae (mean count of 78 guttae per 1× 1mm test frame, overestimation:+10 per frame), but had a tendency to significantly overestimate guttae size (mean guttae size 1073μm2, overestimation:+255μm2). Automated measurements of guttae counts and sizes were reproducible within a 1% discrepancy range across repeat intra-eye assessments. Automated guttae counts, interguttae distances, and density of interguttae gaps lesser than 40μm (ie, D40 density) were highly correlated with the Krachmer scale (P < .001 for all). Large-scale guttae assessment demonstrated the automated system's potential to selectively identify a region of the corneal endothelium most affected by densely packed guttae. Automated guttae assessment facilitates the precise identification and quantification of guttae characteristics in FECD patients. This can be used clinically as a personalized descemetorrhexis zone for Descemet stripping only and/or Descemet membrane transplantation.

TCF4-mediated Fuchs endothelial corneal dystrophy: Insights into a common trinucleotide repeat-associated disease.

Fuchs endothelial corneal dystrophy (FECD) is a common cause for heritable visual loss in the elderly. Since the first description of an association between FECD and common polymorphisms situated within the transcription factor 4 (TCF4) gene, genetic and molecular studies have implicated an intronic CTG trinucleotide repeat (CTG18.1) expansion as a causal variant in the majority of FECD patients. To date, several non-mutually exclusive mechanisms have been proposed that drive and/or exacerbate the onset of disease. These mechanisms include (i) TCF4 dysregulation; (ii) toxic gain-of-function from TCF4 repeat-containing RNA; (iii) toxic gain-of-function from repeat-associated non-AUG dependent (RAN) translation; and (iv) somatic instability of CTG18.1. However, the relative contribution of these proposed mechanisms in disease pathogenesis is currently unknown. In this review, we summarise research implicating the repeat expansion in disease pathogenesis, define the phenotype-genotype correlations between FECD and CTG18.1 expansion, and provide an update on research tools that are available to study FECD as a trinucleotide repeat expansion disease. Furthermore, ongoing international research efforts to develop novel CTG18.1 expansion-mediated FECD therapeutics are highlighted and we provide a forward-thinking perspective on key unanswered questions that remain in the field.

Corneal optical density in Fuchs endothelial dystrophy determined by anterior segment optical coherence tomography.

In this study, we propose a method to grade corneal stromal opacity using optical density measurements by anterior segment optical coherence tomography (AS-OCT) and validate the approach in Fuchs endothelial corneal dystrophy (FECD). A retrospective analysis of human corneal OCT scans was performed on 48 eyes of 32 patients with FECD and 33 control eyes of 21 patients using the Carl Zeiss Cirrus HD-OCT 5000. In addition, corneal edema in fresh rabbit cadaver eyes was artificially induced by distilled water and imaged with the Thorlabs TELESTO-II spectral domain OCT at different time points during saturation. The increase of opacity due to corneal edema was proposed to directly correlate with enhanced reflectivity sites in the OCT images, corresponding to higher optical density. The increase was determined as the image area above a statistically established gray-scale value using ImageJ and correlated with other disease characteristics. Optical densities in human corneas showed significant differences between FECD patients and the control group (p = 0.002). The increased optical densities determined in FECD corneas correlated well with other disease characteristics such as corneal pachymetry or visual acuity. Likewise, rabbit corneas showed a time dependent increase in thickness and in corneal optical density during soaking in distilled water. This study presents corneal optical density by AS-OCT as an objective value for corneal changes in FECD. Complementing other diagnostic tools in FECD the assessment of corneal optical density may identify progression of FECD, gauge novel therapeutic strategies and support risk and benefit analyses for corneal surgery.

Regenerative medicine in Fuchs' endothelial corneal dystrophy.

The management of Fuchs' endothelial corneal dystrophy (FECD) has evolved rapidly since the introduction of endothelial keratoplasty (EK). In recent years, advances in our understanding of endothelial cell biology, in particular with respect to the regenerative capacity of endothelial cells, have opened the door to novel therapeutic options that stray from the traditional paradigm of allograft transplantation. We review the development of descemetorhexis without EK (DWEK) as a primary treatment for FECD and discuss the lessons learned to date about the mechanism of wound healing, surgical technique, patient selection, and refractive outcomes. Multiple randomized clinical trials are currently underway to evaluate the potential for pharmacological supplementation with rho-associated kinase inhibitors to increase the success rate of corneal clearance following DWEK. Biologic supplementation with intracameral endothelial cell injection and acellular Descemet's membrane transplantation are other avenues of adjuvant therapy. DWEK is a promising surgical option for management of a subset of FECD patients.

Fuchs endothelial corneal dystrophy: The vicious cycle of Fuchs pathogenesis.

Fuchs endothelial corneal dystrophy (FECD) is the most common primary corneal endothelial dystrophy and the leading indication for corneal transplantation worldwide. FECD is characterized by the progressive decline of corneal endothelial cells (CECs) and the formation of extracellular matrix (ECM) excrescences in Descemet's membrane (DM), called guttae, that lead to corneal edema and loss of vision. FECD typically manifests in the fifth decades of life and has a greater incidence in women. FECD is a complex and heterogeneous genetic disease where interaction between genetic and environmental factors results in cellular apoptosis and aberrant ECM deposition. In this review, we will discuss a complex interplay of genetic, epigenetic, and exogenous factors in inciting oxidative stress, auto(mito)phagy, unfolded protein response, and mitochondrial dysfunction during CEC degeneration. Specifically, we explore the factors that influence cellular fate to undergo apoptosis, senescence, and endothelial-to-mesenchymal transition. These findings will highlight the importance of abnormal CEC-DM interactions in triggering the vicious cycle of FECD pathogenesis. We will also review clinical characteristics, diagnostic tools, and current medical and surgical management options for FECD patients. These new paradigms in FECD pathogenesis present an opportunity to develop novel therapeutics for the treatment of FECD.

Ex vivo excimer laser ablation of cornea guttata and ROCK inhibitor-aided endothelial recolonization of ablated central cornea.

To determine whether excimer laser ablation of guttae is a viable strategy for removal of diseased tissue in Fuchs' endothelial corneal dystrophy (FECD) on excised human Descemet membranes and whether an excimer laser-created wound on healthy human corneas ex vivo is recolonized with corneal endothelial cells. Descemet membranes of FECD patients and corneal endothelium of normal human corneas were ablated ex vivo using an excimer laser licensed for glaucoma surgery. Specimens were kept in cell culture medium supplemented with 10μm of rho-kinase inhibitor ripasudil. Corneal endothelial cell regeneration was observed using light and electron scanning microscopy. Furthermore, the whole corneal samples were evaluated by haematoxylin/eosin staining and immunohistochemical analysis using antibodies against Na+ /K+ -ATPase. Guttae and corneal endothelium could be ablated with an excimer laser without total ultrastructural damage to theDescemet membrane or stroma. Nearly complete endothelial wound closure was accomplished after 26-38days in treated corneas. Light and electron scanning microscopy suggested the establishment of a layer of flat endothelial cells. Additionally, Na+ /K+ -ATPase expression could only be observed on the inner side of the Descemet membrane. Our proof of concept study demonstrated that excimer lasers can be used to ablate diseased tissue from excised FECD Descemet membranes ex vivo. Additionally, corneal endothelial cells recolonize a previously ablated endothelial area in healthy human corneas ex vivo under treatment with ripasudil. Thus, our results are the first experimental basis to further investigate the feasibility of an excimer laser ablation as a graftless FECD treatment option.