Fuchs endothelial corneal dystrophy

MicroRNAs in Corneal Diseases: Emerging Roles as Biomarkers, Regulators, and Therapeutics

MicroRNAs (miRNAs) are conserved, short, non-coding RNAs that play a crucial role in regulating gene expression. Emerging evidence suggests that miRNAs are closely involved in the pathophysiology of various corneal diseases, particularly in regulating corneal wound healing, inflammation and neovascularization. In this review, we summarized the recent progress of miRNAs in corneal diseases, especially focused on their application as diagnostic biomarkers, regulators of cell biology, and therapeutic targets. Recent advances in miRNA detection technology have made it possible to analyze minimal miRNAs in samples such as tears or exosomes, further enhancing the ability to identify disease-specific miRNA profiles and providing potential objective indicators for the early diagnosis of disease. Meanwhile, we summarized the mechanisms and pathways of multiple miRNAs in regulating various biological processes of corneal cells, as well as the advantages of studying miRNA compared to proteins or genes. Furthermore, we explore the potential of miRNAs-based therapies, especially introduce various miRNA delivery systems and challenges associated with clinical translation. This review highlights the need for further research to harness the full potential of miRNAs in treating various corneal diseases.

DNA methylation modification: Dawn of research on cornea-related diseases

DNA methylation is a significant form of epigenetic modification that plays a crucial role in the occurrence and progression of diseases by regulating gene expression. Recent advancements in our understanding of DNA methylation have demonstrated its involvement in corneal damage repair and various corneal diseases. This article reviews the mechanisms and effects of DNA methylation modifications in corneal injury repair, keratoconus, corneal dystrophy, keratitis, and other related conditions. The aim is to enhance our understanding of the vital role of DNA methylation in the pathogenesis of corneal injuries and the development of cornea-related diseases. The phenomenon of DNA methylation in these conditions may offer new ideas and insights for therapeutic approaches.

Characterisation of the role played by ELMO1, GPR141 and the intergenic polymorphism rs918980 in Fuchs' dystrophy in the Indian population

Fuchs' endothelial corneal dystrophy (FECD) is the most common type of primary corneal dystrophy and can result in corneal transplantation. Here, we investigated the genetic association of SNP rs918980 (A>G) with FECD and the role of its surrounding genes ELMO1 and GPR141. First, 128 patients and 379 controls were genotyped by Sanger sequencing. Our results show that rs918980 is significantly associated with FECD in the Indian population. Furthermore, in silico analysis suggested that rs918980 and its surrounding 150 bp region could regulate the transcriptional activities of nearby genes. Thus, we assessed whether ELMO1 and GPR141 were differentially expressed in FECD patients and in the corneal tissue of a UVA-induced FECD mice model. Both genes were significantly upregulated and western blots studies concluded that protein levels of ELMO1 and GPR141 were also higher in the corneal endothelium of the UVA-exposed eye compared to the control eye. Taken together, our results suggest that ELMO1 and GPR141 might play a significant role in FECD progression. However, further studies are required to better characterize the possible role of rs918980 and its nearby region in the regulation of ELMO1 and GPR141.

Lycopene Protects Corneal Endothelial Cells from Oxidative Stress by Regulating the P62-Autophagy-Keap1/Nrf2 Pathway

Oxidative stress is a key mechanism in corneal endothelial damage-related diseases, which is induced by environmental factors and genetic mutations. Lycopene (LYC), one of the most potent natural antioxidants, has been shown to offer significant protection against various diseases. However, its role and mechanisms in corneal endothelial damage remain unclear. In this study, an oxidative stress-induced injury model was created using the B4G12 cell line, and a disease model for Fuchs' endothelial corneal dystrophy (FECD) was established using genetically edited mice, both of which were treated with LYC. The results demonstrated that lycopene effectively protected corneal endothelial cells and slowed the progression of FECD. The protective mechanism involves upregulating P62 and activating autophagy, leading to Keap1 degradation, Nrf2 nuclear translocation, and activation of downstream antioxidant proteins. This study broadens the potential application of lycopene in protecting the corneal endothelium and provides a new non-surgical approach for treating corneal endothelial damage-related diseases.

The prevalence of corneal guttata and its related risk factors in a Thai population: a community-based study in central Thailand

This is a large cross-sectional, population-based survey to investigate the prevalence of central corneal guttata in the Thai population. Two communities in the central region of Thailand are (1) Phanat Nikhom district, Chonburi, and (2) Khlong Toey district, Bangkok. All participants completed an interview and ophthalmic examination. Overall, 990 participants aged ≥ 40 years were included. The prevalence of central corneal guttata was 40.80% (399/978 participants); 328/978 participants (33.54%) exhibited modified Krachmer grade I corneal guttata. The study utilized definitive diagnosis and severity grading, using the modified Krachmer grading scale, to estimate the prevalence within the general population and to identify potential risk factors. The presence of central corneal guttata was evaluated by three corneal specialists (VP, VS, and PP) using a slit-lamp biomicroscope and the NIDEK CEM-530 specular microscope (NIDEK, Aichi, Japan). The estimated overall prevalence in the Thai population was 45.76%, with an approximate female-to-male ratio of 1.35:1. Multiple logistic regression analysis showed that only age ≥ 50 years, compared with age 40-49 years, was a significant risk factor for the presence of central corneal guttata. In conclusion, this study showed that the prevalence of central corneal guttata (mainly sporadic cases) in the Thai population was as high as 45.76%.

Preclinical Models for Studying Fuchs Endothelial Corneal Dystrophy

Fuchs Endothelial Corneal Dystrophy (FECD) is a corneal endothelial disease that causes microenvironment alterations and endothelial cell loss, which leads to vision impairment. It has a high global prevalence, especially in elderly populations. FECD is also one of the leading indications of corneal transplantation globally. Currently, there is no clearly defined canonical pathway for this disease, and it has been proposed that the combinatorial effects of genetic mutations and exogenous factors cause FECD. Clinical studies and observations have provided valuable knowledge and understanding of FECD, while preclinical studies are essential for gaining insights into disease progression and mechanisms for the development and testing of regenerative medicine therapies. In this review, we first introduce the proposed genetic and molecular pathologies of FECD. Notably, we discuss the impact of abnormal extracellular matrix deposition (guttata), endothelial-to-mesenchymal transition, cell senescence, and oxidative stress on the pathology and etiology of FECD. We review and summarize the in vitro cell models, ex vivo tissues, and in vivo animal models used to study FECD. The benefits and challenges of each model are also discussed.

Anatomic Characteristics of Eyes With Fuchs Endothelial Corneal Dystrophy

PURPOSE

The purpose of this study was to evaluate and compare the anatomic characteristics of eyes with Fuchs endothelial corneal dystrophy (FECD) with eyes without FECD.

METHODS

This study was a retrospective chart review performed at an academic medical center. Patients with FECD were identified through a search of the electronic medical records. Eligible patients underwent Scheimpflug imaging and optical biometry and were compared with age and sex-matched control subjects who underwent similar testing in preparation for cataract surgery. Several measurements of the cornea, anterior chamber, and eyes were evaluated using multivariable linear regression models and multivariable logistic regression models.

RESULTS

A total of 404 eyes (202 eyes with FECD and 202 control eyes) were included in this study. Compared with controls, eyes with FECD had shallower AC depths, lower AC volumes, and narrower angles. Conversely, the spherical equivalent before cataract surgery, corneal pachymetry, and corneal volume were higher in eyes with FECD. On Scheimpflug imaging analysis, these anatomical differences were present in FECD eyes with and without corneal edema. After adjusting for sex, these differences remained statistically significant. Shorter axial length was found to be statistically significant in male eyes but not in female eyes with FECD.

CONCLUSIONS

This study reports new ocular characteristics in FECD eyes with and without edema. Optical biometry and Scheimpflug imaging established that the anatomic findings in eyes with FECD were not simply due to the larger volume of an edematous cornea but rather unique to eyes with FECD. These findings will provide reliable, normative data for future studies examining surgical, medical, and anatomical factors in FECD.

Preoperative edema severity affects outcomes after Descemet membrane endothelial keratoplasty for Fuchs endothelial corneal dystrophy: a cohort study

BACKGROUND

In patients with Fuchs endothelial corneal dystrophy (FECD), the most beneficial stage to perform Descemet membrane endothelial keratoplasty (DMEK) remains uncertain. The goal of this study was to compare the surgical outcomes after DMEK in FECD patients with subclinical corneal edema and clinical corneal edema to test the hypothesis of whether performing surgery in subclinical corneal edema stages achieves better surgical outcomes.

METHODS

In this prospective, observational, single-institution cohort study, 106 pseudophakic eyes of 85 patients with FECD were divided into two groups depending on the presence of preoperative subclinical and clinical corneal edema. Subclinical corneal edema was diagnosed if more than one of the following criteria was present in Scheimpflug tomography: loss of regular isopachs, displacement of the thinnest point of the cornea, and focal posterior corneal surface depression. Clinical corneal edema was diagnosed with slit-lamp biomicroscopy. The primary outcome was the corrected distance visual acuity (CDVA) 4 months after DMEK. Secondary outcomes were central corneal thickness (CCT), thinnest corneal thickness (TCT), and total corneal density (TCD) in Scheimpflug tomography, as well as endothelial cell loss (ECL) and the re-bubbling rate. The differences between both groups were analyzed using clustered Wilcoxon rank-sum tests or a Chi-squared test.

RESULTS

Postoperative CDVA was significantly better in the group with subclinical edema (0.18 ± 0.12 logMAR) compared to the group with clinical edema (0.24 ± 0.19 logMAR; P = 0.026). Four months after DMEK, TCD was higher in the group with preoperative clinical edema [31.7 ± 8.3 gray scale units (GSU)] compared to the group with subclinical edema (27.8 ± 6.1 GSU; P = 0.005). The postoperative CCT, TCT, ECL, and re-bubbling rates did not differ significantly between both groups (all P > 0.05).

CONCLUSIONS

DMEK for FECD yielded better visual acuity after 4 months when performed in the early stage of FECD compared to a later stage with clinical edema. This may be attributable to persistent corneal fibrosis after DMEK in eyes with preoperative clinically evident corneal edema, as suggested by higher postoperative corneal density in eyes with clinical edema. Consequently, the findings advocate for the consideration of earlier DMEK in FECD patients to achieve better surgical recovery.

Endoplasmic Reticulum-Mitochondria Crosstalk in Fuchs Endothelial Corneal Dystrophy: Current Status and Future Prospects

Fuchs endothelial corneal dystrophy (FECD) is a progressive and debilitating disorder of the corneal endothelium (CE) that affects approximately 4% of individuals over the age of 40. Despite the burden of the disease, the pathogenesis of FECD remains poorly understood, and treatment options are limited, highlighting the need for deeper investigation into its underlying molecular mechanisms. Over the past decade, studies have indicated independent contributions of endoplasmic reticulum (ER) and mitochondrial stress to the pathogenesis of FECD. However, there are limited studies suggesting ER-mitochondria crosstalk in FECD. Recently, our lab established the role of chronic ER stress in inducing mitochondrial dysfunction for corneal endothelial cells (CEnCs), indicating the existence of ER-mitochondria crosstalk in FECD. This paper aims to provide a comprehensive overview of the current understanding of how ER and mitochondrial stress contribute to FECD pathogenesis. The paper also reviews the literature on the mechanisms of ER-mitochondria crosstalk in other diseases relevant to FECD.

Ripasudil's paradox: bullous keratopathy with honeycomb twist

We present a case of a male patient in his mid-50s who presented with bullous keratopathy secondary to an anterior chamber intraocular lens, complicated by superimposed honeycomb keratopathy while on ripasudil 0.4%. The bullous keratopathy was characterised by generalised microcystic epithelial oedema, alongside more centrally located, variable-sized macrocystic epithelial oedema with a honeycomb appearance. Discontinuation of ripasudil resulted in the resolution of the honeycomb keratopathy, although with the persistence of pre-existing microcystic corneal oedema. This case highlights the complexity of ripasudil's effects on corneal endothelium, showing a paradoxical response. Timely identification of ripasudil-induced keratopathy is crucial, particularly in cases when it is started elsewhere, emphasising the necessity for vigilant monitoring and management strategies.

Outcomes of Descemet Stripping Only Without Postoperative Use of Topical Rho-Associated Protein Kinase Inhibitors

PURPOSE

Descemet stripping only (DSO) is a promising surgical option for select patients with Fuchs endothelial dystrophy (FED). There is growing support for the use of topical Rho-associated protein kinase inhibitors (ROCKi) to optimize DSO outcomes. However, in many settings, ROCKi are either unavailable or not approved to treat corneal diseases. This study sought to characterize patient outcomes after DSO in the absence of ROCKi and potentially broaden the settings where DSO can be offered to patients.

METHODS

Single-center retrospective case series of 15 eyes/11 patients (66 years; 52-74) that underwent DSO, alone or combined with cataract surgery, by one surgeon between August 2020 and January 2023. Patients included in analyses had FED with central guttae, no clinical evidence of corneal edema, and a clinically healthy peripheral corneal endothelium.

RESULTS

Mean follow-up time was 14 months (2-34). Fourteen of 15 eyes achieved corneal clearance (93.3%). Mean time to clearance was 8.5 weeks (3-23). Eleven eyes (73%) achieved corrected distance visual acuity of ≤0.2 with a significant postoperative improvement at 4 to 8 months ( P < 0.05) and sustained improvements at >12 months. No significant astigmatism was introduced by the procedure. Two eyes developed cystoid macular edema postoperatively. A trend toward earlier clearance was observed in the <65 years old group.

CONCLUSIONS

Despite a longer time to corneal clearance in this cohort compared with the few studies using ROCKi, the overall success rate and visual outcomes for the patients in our cohort supports the use of DSO in settings where ROCKi are not readily available.

Evolution of therapeutic strategy based on oxidant-antioxidant balance for fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) stands as the most prevalent primary corneal endothelial dystrophy worldwide, posing a significant risk to corneal homeostasis and clarity. Corneal endothelial cells exhibit susceptibility to oxidative stress, suggesting a nuanced relationship between oxidant-antioxidant imbalance and FECD pathogenesis, irrespective of FECD genotype. Given the constrained availability of corneal transplants, exploration into non-surgical interventions becomes crucial. This encompasses traditional antioxidants, small molecule compounds, biologics, and diverse non-drug therapies, such as gene-related therapy, hydrogen therapy and near infrared light therapy. This review concentrates on elucidating the mechanisms behind oxidant-antioxidant imbalance and the evolution of strategies to restore oxidant-antioxidant balance in FECD. It provides a comprehensive overview of both conventional and emerging therapeutic approaches, offering valuable insights for the advancement of non-surgical treatment modalities. The findings herein might establish a robust foundation for future research and the therapeutic strategy of FECD.

MitoQ relieves mitochondrial dysfunction in UVA and cigarette smoke-induced Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD), a degenerative corneal condition, is characterized by the droplet-like accumulation of the extracellular matrix, known as guttae and progressive loss of corneal endothelial cells ultimately leading to visual distortion and glare. FECD can be influenced by environmental stressors and genetic conditions. However, the role of mitochondrial dysfunction for advancing FECD pathogenesis is not yet fully studied. Therefore, in the present study we sought to determine whether a combination of environmental stressors (ultraviolet-A (UVA) light and cigarette smoke condensate (CSC)) can induce mitochondrial dysfunction leading to FECD. We also investigated if MitoQ, a water-soluble antioxidant, can target mitochondrial dysfunction induced by UVA and CSC in human corneal endothelial cells mitigating FECD pathogenesis. We modeled the FECD by increasing exogenous oxidative stress with CSC (0.2%), UVA (25J/cm2) and a combination of UVA + CSC and performed a temporal analysis of their cellular and mitochondrial effects on HCEnC-21T immortalized cells in vitro before and after MitoQ (0.05 μM) treatment. Interestingly, we observed that a combination of UVA + CSC exposure increased mitochondrial ROS and fragmentation leading to a lower mitochondrial membrane potential and increased levels of cytochrome c release leading to apoptosis and cell death. MitoQ intervention successfully mitigated these effects and restored cell viability. The UVA + CSC model could be used to study stress induced mitochondrial dysfunction. Additionally, MitoQ can serve as a viable antioxidant in attenuating mitochondrial dysfunction, underscoring its potential as a molecular-focused treatment approach to combat FECD pathogenesis.

Fuchs' Endothelial Corneal Dystrophy evaluation using a high-resolution wavefront sensor

This study aims to evaluate the applicability of the high-resolution WaveFront Phase Imaging Sensor (WFPI) in eyes with Fuchs' Endothelial Corneal Dystrophy (FECD) through qualitative and quantitative analysis using a custom-designed Automatic Guttae Detection Method (AGDM). The ocular phase was measured using the t · eyede aberrometer and then was processed to obtain its High-Pass Filter Map (HPFM). The subjects were pathological and healthy patients from the Fundación Jiménez-Díaz Hospital (Madrid, Spain). The AGDM was developed and applied in pupils with 3 and 5 mm of diameter. A set of metrics were extracted and evaluated like the Root-Mean-Square error (RMS), Number of guttae, Guttae Area, and Area of Delaunay Triangulation (DT). Finally, a Support Vector Machine (SVM) model was trained to classify between pathological and healthy eyes. Quantitatively, the HPFM reveals a dark spots pattern according to the ophthalmologist's description of the slit-lamp examination of guttae distribution. There were significant statistical differences in all the metrics when FECD and Healthy groups were compared using the same pupil size; but comparing both pupil sizes for the same group there were significant differences in most of the variables. This sensor is a value tool to objectively diagnose and monitor this pathology through wavefront phase changes.

Exploring single-cell RNA sequencing as a decision-making tool in the clinical management of Fuchs' endothelial corneal dystrophy

Single-cell RNA sequencing (scRNA-seq) has enabled the identification of novel gene signatures and cell heterogeneity in numerous tissues and diseases. Here we review the use of this technology for Fuchs' Endothelial Corneal Dystrophy (FECD). FECD is the most common indication for corneal endothelial transplantation worldwide. FECD is challenging to manage because it is genetically heterogenous, can be autosomal dominant or sporadic, and progress at different rates. Single-cell RNA sequencing has enabled the discovery of several FECD subtypes, each with associated gene signatures, and cell heterogeneity. Current FECD treatments are mainly surgical, with various Rho kinase (ROCK) inhibitors used to promote endothelial cell metabolism and proliferation following surgery. A range of emerging therapies for FECD including cell therapies, gene therapies, tissue engineered scaffolds, and pharmaceuticals are in preclinical and clinical trials. Unlike conventional disease management methods based on clinical presentations and family history, targeting FECD using scRNA-seq based precision-medicine has the potential to pinpoint the disease subtypes, mechanisms, stages, severities, and help clinicians in making the best decision for surgeries and the applications of therapeutics. In this review, we first discuss the feasibility and potential of using scRNA-seq in clinical diagnostics for FECD, highlight advances from the latest clinical treatments and emerging therapies for FECD, integrate scRNA-seq results and clinical notes from our FECD patients and discuss the potential of applying alternative therapies to manage these cases clinically.

Influence of Subclinical Corneal Edema on Contrast Sensitivity in Fuchs Endothelial Corneal Dystrophy

PURPOSE

The aim of this study was to compare visual function, with a focus on contrast sensitivity, between patients with Fuchs endothelial corneal dystrophy (FECD) with and without subclinical corneal edema.

METHODS

In this cross-sectional, observational, single-center study, 46 pseudophakic eyes of 31 patients with FECD were divided into 2 groups depending on the presence of subclinical corneal edema. All eyes presented with a Krachmer grade of 5 and no clinical corneal edema. The criteria for subclinical corneal edema were loss of regular isopachs, displacement of the thinnest point, and focal posterior surface depression in Scheimpflug tomography. If more than 1 criterion was present, subclinical corneal edema was diagnosed. The corrected distance visual acuity, contrast sensitivity (Pelli-Robson chart and CSV-1000 test with optional glare), and straylight were measured. The differences between both groups were analyzed using clustered Wilcoxon rank-sum tests.

RESULTS

The corrected distance visual acuity and the contrast sensitivity, measured with a Pelli-Robson chart, were significantly inferior in eyes with subclinical corneal edema compared with eyes without subclinical edema ( P < 0.05). At all spatial frequencies, eyes with subclinical edema demonstrated lower contrast sensitivity with a statistically significantly reduction in total contrast sensitivity when tested with ( P = 0.005) and without ( P = 0.002) glare. The straylight did not significantly differ between both groups ( P > 0.05).

CONCLUSIONS

The corrected distance visual acuity and contrast sensitivity were significantly reduced in FECD eyes with subclinical corneal edema compared with those with no subclinical edema. This decrease in visual quality may be considered when evaluating the need for surgical intervention at earlier stages of FECD.

Expression of Hormones' Receptors in Human Corneal Endothelium from Fuchs' Dystrophy: A Possible Gender' Association

Background: Age and sex are the most significant risk of factors for advanced Fuchs dystrophy. Nevertheless, few data are available on the hormone's receptor pattern expressed in adult and advanced fuchs endothelial corneal dystrophy (FECD). We investigated the impact of gender, growth factors and extracellular matrix (ECM) regulatory proteins expressed by the dystrophic endothelia. Methods: Ten dystrophic endothelial tissues and 10 normal endothelial sheets (corneoscleral specimens; Eye Bank) were used for this characterization study. Hormones' receptors (ERα, AR, PR, SHBG), few growth factors (VEGFA, βNGF, TGFβ1), some ECM regulators (MMP1, MMP7) and few inflammatory cytokines (IFNγ, IL10) were analyzed by real-time RT-PCR. Results: ERα transcripts were significantly increased, AR and SHBG transcripts were decreased in Fuchs endothelia from female patients, and no changes were detected for PR transcripts. VEGFA, βNGF and TGFβ1 transcripts were upregulated in Fuchs' endothelia, but not significantly linked to gender. High MMP1 and low MMP7 transcripts' expression were detected in Fuchs' specimens, mainly in males than females. An increased IFNγ (Th1) transcript expression was observed in females than males, and a trend to increase for IL10 (Th2) transcripts was detected in males than females. Conclusions: Our findings clearly indicate that hormone receptors, growth factors and matrix mediators as well as a Th1 pathway are predominant in Fuchs' dystrophy, displaying a pattern of expression specific for the female phenotype. The differential expression of hormones' receptors and the Th1/Th2 ratio might prompt to new theories to be tested in vitro and in vivo models, such as the use of hormonal substitute for counteracting this endothelial cell lost.

Dysregulation of the TCF4 Isoform in Corneal Endothelial Cells of Patients With Fuchs Endothelial Corneal Dystrophy

Purpose

This study evaluated the dysregulation of TCF4 isoforms and differential exon usage (DEU) in corneal endothelial cells (CECs) of Fuchs endothelial corneal dystrophy (FECD) with or without trinucleotide repeat (TNR) expansion in the intron region of the TCF4 gene.

Methods

Three RNA-Seq datasets of CECs (our own and two other previously published datasets) derived from non-FECD control and FECD subjects were analyzed to identify TCF4 isoforms and DEU events dysregulated in FECD by comparing control subjects to those with FECD with TNR expansion and FECD without TNR expansion.

Results

Our RNA-Seq data demonstrated upregulation of three TCF4 isoforms and downregulation of two isoforms in FECD without TNR expansion compared to the controls. In FECD with TNR expansion, one isoform was upregulated and one isoform was downregulated compared to the control. Additional analysis using two other datasets identified that the TCF4-277 isoform was upregulated in common in all three datasets in FECD with TNR expansion, whereas no isoform was dysregulated in FECD without TNR expansion. DEU analysis showed that one exon (E174) upstream of the TNR, which only encompassed TCF4-277, was upregulated in common in all three datasets, whereas eight exons downstream of the TNR were downregulated in common in all three datasets in FECD with TNR expansion.

Conclusions

This study identified TCF4-277 as a dysregulated isoform in FECD with TNR expansion, suggesting a potential contribution of TCF4-277 to FECD pathophysiology.

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.

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.

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.

Translation and validation of the Visual Function and Corneal Health Status (V-FUCHS) questionnaire into Spanish language

PURPOSE

To translate and validate the V-FUCHS questionnaire into Spanish in a population of patients with Fuchs endothelial dystrophy (DEF).

METHODS

The V-FUCHS consists of 15 short, easily understandable questions that assess visual aspects of quality of life in patients with DEF, which can be gathered into a group of seven that assess the "Visual Difficulty" factor and another group of eight that assess the "Glare Factor". For the translation and cultural adaptation, the standardized norms for this process were followed, among other phases, a translation, a back-translation and an application in patients with DEF.

RESULTS

In the first phase, consensus was reached on the Spanish translation of the V-FUCHS. Subsequently, 25 patients were included to carry out the pre-test phase with the aim of assessing the applicability and feasibility of the test. The score obtained a minimum value of -0.88 and a maximum value of +2.44, according to the Rasch probabilistic scale. The mean value obtained from the Visual Difficulty factor was 0.61 (±0.71), while the mean for the Glare Factor was 0.41 (±0.51).

CONCLUSION

The validation of the V-FUCHS questionnaire, after its translation and adaptation into Spanish, proved to be a useful tool for assessing the visual quality of patients with DEF. Patients with a more advanced stage of the disease presented a greater severity in the test result. Likewise, the Glare Factor (Glare) correlates better with the pachymetric increase than with the visual acuity of the patient.

Therapeutic future of Fuchs endothelial corneal dystrophy: An ongoing way to explore

Fuchs endothelial corneal dystrophy (FECD) is one of the most common corneal diseases that causes loss of visual acuity in the world. FECD is a genetically and pathogenetically heterogeneous disease that results in the failure of corneal endothelial cells to maintain fluid balance and functional homeostasis of the cornea. Corneal edema, central guttae formation, and bullae development are common corneal pathologies. Currently, the mainstay of FECD treatment is surgery. However, limited sources of corneal graft and postsurgical complications remain problematic. In recent years, with advances in medical science and technology, there have been a few promising trials of new treatment modalities for FECD. In addition to new surgical methods, novel modalities can be classified into pharmacological-associated treatment, cell therapy-associated treatment, and gene therapy-associated treatment. In this article, our primary focus is on the most recent clinical trials related to FECD, and we present a stepwise approach to enhance FECD management and ultimately improve patient outcomes. We thoroughly searched for FECD clinical trials and reviewed the study designs, methodologies, and outcomes of each trial conducted within the past decade. It is imperative for physicians to stay up-to-date with these cutting-edge treatment approaches.

Transcriptomic meta-analysis reveals ERRα-mediated oxidative phosphorylation is downregulated in Fuchs' endothelial corneal dystrophy

BACKGROUND

Late-onset Fuchs' endothelial corneal dystrophy (FECD) is a degenerative disease of cornea and the leading indication for corneal transplantation. Genetically, FECD patients can be categorized as with (RE+) or without (RE-) the CTG trinucleotide repeat expansion in the transcription factor 4 gene. The molecular mechanisms underlying FECD remain unclear, though there are plausible pathogenic models proposed for RE+ FECD.

METHOD

In this study, we performed a meta-analysis on RNA sequencing datasets of FECD corneal endothelium including 3 RE+ datasets and 2 RE- datasets, aiming to compare the transcriptomic profiles of RE+ and RE- FECD. Gene differential expression analysis, co-expression networks analysis, and pathway analysis were conducted.

RESULTS

There was a striking similarity between RE+ and RE- transcriptomes. There were 1,184 genes significantly upregulated and 1,018 genes significantly downregulated in both RE+ and RE- cases. Pathway analysis identified multiple biological processes significantly enriched in both-mitochondrial functions, energy-related processes, ER-nucleus signaling pathway, demethylation, and RNA splicing were negatively enriched, whereas small GTPase mediated signaling, actin-filament processes, extracellular matrix organization, stem cell differentiation, and neutrophil mediated immunity were positively enriched. The translational initiation process was downregulated in the RE+ transcriptomes. Gene co-expression analysis identified modules with relatively distinct biological processes enriched including downregulation of mitochondrial respiratory chain complex assembly. The majority of oxidative phosphorylation (OXPHOS) subunit genes, as well as their upstream regulator gene estrogen-related receptor alpha (ESRRA), encoding ERRα, were downregulated in both RE+ and RE- cases, and the expression level of ESRRA was correlated with that of OXPHOS subunit genes.

CONCLUSION

Meta-analysis increased the power of detecting differentially expressed genes. Integrating differential expression analysis with co-expression analysis helped understand the underlying molecular mechanisms. FECD RE+ and RE- transcriptomic profiles are much alike with the hallmark of downregulation of genes in pathways related to ERRα-mediated OXPHOS.

Animal Models in Eye Research: Focus on Corneal Pathologies

The eye is a complex sensory organ that enables visual perception of the world. The dysfunction of any of these tissues can impair vision. Conduction studies on laboratory animals are essential to ensure the safety of therapeutic products directly applied or injected into the eye to treat ocular diseases before eventually proceeding to clinical trials. Among these tissues, the cornea has unique homeostatic and regenerative mechanisms for maintaining transparency and refraction of external light, which are essential for vision. However, being the outermost tissue of the eye and directly exposed to the external environment, the cornea is particularly susceptible to injury and diseases. This review highlights the evidence for selecting appropriate animals to better understand and treat corneal diseases, which rank as the fifth leading cause of blindness worldwide. The development of reliable and human-relevant animal models is, therefore, a valuable research tool for understanding and translating fundamental mechanistic findings, as well as for assessing therapeutic potential in humans. First, this review emphasizes the unique characteristics of animal models used in ocular research. Subsequently, it discusses current animal models associated with human corneal pathologies, their utility in understanding ocular disease mechanisms, and their role as translational models for patients.

Biomaterials used for tissue engineering of barrier-forming cell monolayers in the eye

Cell monolayers that form a barrier between two structures play an important role for the maintenance of tissue functionality. In the anterior portion of the eye, the corneal endothelium forms a barrier that controls fluid exchange between the aqueous humor of the anterior chamber and the corneal stroma. This monolayer is central in the pathogenesis of Fuchs endothelial corneal dystrophy (FECD). FECD is a common corneal disease, in which corneal endothelial cells deposit extracellular matrix that increases the thickness of its basal membrane (Descemet's membrane), and forms excrescences (guttae). With time, there is a decrease in endothelial cell density that generates vision loss. Transplantation of a monolayer of healthy corneal endothelial cells on a Descemet membrane substitute could become an interesting alternative for the treatment of this pathology. In the back of the eye, the retinal pigment epithelium (RPE) forms the blood-retinal barrier, controlling fluid exchange between the choriocapillaris and the photoreceptors of the outer retina. In the retinal disease dry age-related macular degeneration (dry AMD), deposits (drusen) form between the RPE and its basal membrane (Bruch's membrane). These deposits hinder fluid exchange, resulting in progressive RPE cell death, which in turn generates photoreceptor cell death, and vision loss. Transplantation of a RPE monolayer on a Bruch's membrane/choroidal stromal substitute to replace the RPE before photoreceptor cell death could become a treatment alternative for this eye disease. This review will present the different biomaterials that are proposed for the engineering of a monolayer of corneal endothelium for the treatment of FECD, and a RPE monolayer for the treatment of dry AMD.

Crosstalk between TRPV1 and immune regulation in Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) is the leading indication for corneal transplantation worldwide. Our aim was to investigate the role of transient receptor potential vanilloid subtype 1 (TRPV1) and the associated immune regulation contributing to this pathological condition. Significant upregulation of TRPV1 was detected in the H2O2-induced in vitro FECD model. Based on gene expression microarray dataset GSE142538 and in vitro results, a comprehensive immune landscape was studied and a negative correlation was found between TRPV1 with different immune cells, especially regulatory T cells (Tregs). Functional analyses of the 313 TRPV1-related differentially expressed genes (DEGs) revealed the involvement of TRP-regulated calcium transport, as well as inflammatory and immune pathways. Four TRPV1-related core genes (MAPK14, GNB1, GNAQ, and ARRB2) were screened, validated by microarray dataset GSE112039 and the combined validation dataset E-GEAD-399 & 564, and verified by in vitro experiments. Our study suggested a potential crosstalk between TRPV1 and immune regulation contributing to FECD pathogenesis. The identified pivotal biomarkers and immune-related pathways provide a novel framework for future mechanistic and therapeutic studies of FECD.

Association Between Fuchs Endothelial Corneal Dystrophy, Diabetes Mellitus, and Multimorbidity

PURPOSE

The aim of this study was to assess risk for demographic variables and other health conditions that are associated with Fuchs endothelial corneal dystrophy (FECD).

METHODS

We developed a FECD case-control algorithm based on structured electronic health record data and confirmed accuracy by individual review of charts at 3 Veterans Affairs (VA) Medical Centers. This algorithm was applied to the Department of VA Million Veteran Program cohort from whom sex, genetic ancestry, comorbidities, diagnostic phecodes, and laboratory values were extracted. Single-variable and multiple variable logistic regression models were used to determine the association of these risk factors with FECD diagnosis.

RESULTS

Being a FECD case was associated with female sex, European genetic ancestry, and a greater number of comorbidities. Of 1417 diagnostic phecodes evaluated, 213 had a significant association with FECD, falling in both ocular and nonocular conditions, including diabetes mellitus (DM). Five of 69 laboratory values were associated with FECD, with the direction of change for 4 being consistent with DM. Insulin dependency and type 1 DM raised risk to a greater degree than type 2 DM, like other microvascular diabetic complications.

CONCLUSIONS

Female sex, European ancestry, and multimorbidity increased FECD risk. Endocrine/metabolic clinic encounter codes and altered patterns of laboratory values support DM increasing FECD risk. Our results evoke a threshold model in which the FECD phenotype is intensified by DM and potentially other health conditions that alter corneal physiology. Further studies to better understand the relationship between FECD and DM are indicated and may help identify opportunities for slowing FECD progression.

Genomic instability and eye diseases

Background

Genetic information is stored in the bases of double-stranded DNA. However, the integrity of DNA molecules is constantly threatened by various mutagenic agents, including pollutants, ultraviolet light (UV), and medications. To counteract these environmental damages, cells have established multiple mechanisms, such as producing molecules to identify and eliminate damaged DNA, as well as reconstruct the original DNA structures. Failure or insufficiency of these mechanisms can cause genetic instability. However, the role of genome stability in eye diseases is still under-researched, despite extensive study in cancer biology.

Main text

As the eye is directly exposed to the external environment, the genetic materials of ocular cells are constantly under threat. Some of the proteins essential for DNA damage repair, such as pRb, p53, and RAD21, are also key during the ocular disease development. In this review, we discuss five ocular diseases that are associated with genomic instability. Retinoblastoma and pterygium are linked to abnormal cell cycles. Fuchs' corneal endothelial dystrophy and age-related macular degeneration are related to the accumulation of DNA damage caused by oxidative damage and UV. The mutation of the subunit of the cohesin complex during eye development is linked to sclerocornea.

Conclusions

Failure of DNA damage detection or repair leads to increased genomic instability. Deciphering the role of genomic instability in ocular diseases can lead to the development of new treatments and strategies, such as protecting vulnerable cells from risk factors or intensifying damage to unwanted cells.

Oxidative Stress and Cellular Protein Accumulation Are Present in Keratoconus, Macular Corneal Dystrophy, and Fuchs Endothelial Corneal Dystrophy

The aim of the study was to investigate oxidative stress as well as cellular protein accumulation in corneal diseases including keratoconus (KC), macular corneal dystrophy (MCD), and Fuchs endothelial corneal dystrophy (FECD) at their primary affecting sites. Corneal buttons from KC, MCD, and FECD patients, as well as healthy controls, were analyzed immunohistochemically to evaluate the presence of oxidative stress and the function of the proteostasis network. 4-Fydroxynonenal (4-HNE) was used as a marker of oxidative stress, whereas the levels of catalase and heat-shock protein 70 (HSP70) were analyzed to evaluate the response of the antioxidant defense system and molecular chaperones, respectively. Sequestosome 1 (SQSTM1) levels were determined to assess protein aggregation and the functionality of autophagic degradation. Basal epithelial cells of the KC samples showed increased levels of oxidative stress marker 4-HNE and antioxidant enzyme catalase together with elevated levels of HSP70 and accumulation of SQSTM1. Corneal stromal cells and endothelial cells from MCD and FECD samples, respectively, showed similarly increased levels of these markers. All corneal diseases showed the presence of oxidative stress and activation of the molecular chaperone response to sustain protein homeostasis. However, the accumulation of protein aggregates suggests insufficient function of the protective mechanisms to limit the oxidative damage and removal of protein aggregates via autophagy. These results suggest that oxidative stress has a role in KC, MCD, and FECD at the cellular level as a secondary outcome. Thus, antioxidant- and autophagy-targeted therapies could be included as supporting care when treating KC or corneal dystrophies.

Advances in the applications of mesenchymal stem cell-conditioned medium in ocular diseases

Mesenchymal stem cell-conditioned medium (MSC-CM), also known as secretome, is secreted by MSC and contains a variety of bioactive factors with anti-inflammatory, anti-apoptotic, neuroprotection, and proliferation effects. Increasing evidence proved that MSC-CM plays an important role in various diseases, including skin, bone, muscle, and dental diseases. However, the role of MSC-CM in ocular diseases is not quite clear, Therefore, this article reviewed the composition, biological functions, preparation, and characterization of MSC-CM and summarized current research advances in different sources of MSC-CM in corneal and retinal diseases, including dry eye, corneal epithelial damage, chemical corneal injury, retinitis pigmentosa (RP), anterior ischemic optic neuropathy (AION), diabetic retinopathy (DR), and other retinal degenerative changes. For these diseases, MSC-CM can promote cell proliferation, reduce inflammation and vascular leakage, inhibit retinal cell degeneration and apoptosis, protect corneal and retinal structures, and further improves visual function. Hence, we summarize the production, composition and biological functions of MSC-CM and focus on describing its mechanisms in the treatment of ocular diseases. Furthermore, we look at the unexplored mechanisms and further research directions for MSC-CM based therapy in ocular diseases.

Shotgun proteomics identification of proteins expressed in the Descemet's membrane of patients with Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) is a slowly evolving, bilateral disease of the corneal endothelium, characterized by an abnormal accumulation of extracellular matrix (ECM) in the basement membrane (Descemet's membrane, DM). This results in the formation of small round excrescences, called guttae, and a progressive disappearance of endothelial cells. In the intermediate stage, the numerous guttae create significant optical aberrations, and in the late stage, the loss of endothelial function leads to permanent corneal edema. The molecular components of guttae have not been fully elucidated. In the current study, we conducted shotgun proteomics of the DMs, including guttae, obtained from patients with FECD and revealed that 32 proteins were expressed only in the FECD-DMs but not in the DMs of control subjects. Subsequent enrichment analyses identified associations with multiple ECM-related pathways. Immunostaining of flat-mounted DMs confirmed that 4 of the top 5 identified proteins (hemoglobin α, SRPX2, tenascin-C, and hemoglobin γδεβ) were expressed in FECD-DMs but not in non-FECD-DMs. Fibrinogen α was strongly expressed in FECD-DMs, but weakly expressed in non-FECD-DMs. We also demonstrated that matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) can display the in situ spatial distribution of biomolecules expressed in the DM, including the guttae.

Descemet Membrane Endothelial Keratoplasty (DMEK) Reduces the Corneal Epithelial Thickness in Fuchs' Patients

Fuchs' endothelial corneal dystrophy (FECD) is the occurrence of corneal edema due to endothelial cell dystrophy. Descemet membrane endothelial keratoplasty (DMEK) is considered to be the gold standard of treatment. The aim of this study was to investigate the changes in the corneal epithelial thickness of FECD patients before and after DMEK and to compare these results with a healthy control cohort. In this retrospective analysis, 38 eyes of patients with FECD that were treated with DMEK and 35 healthy control eyes received anterior segment optical coherence tomography (OCT; Optovue, XR-Avanti, Fremont, CA, USA). The corneal epithelial thicknesses in different locations were analyzed and compared between the preoperative, postoperative, and control cohorts. The median follow-up time was 9 months. There was a significant degression of the mean epithelial thickness after DMEK in the central, paracentral, and mid-peripheral zones (p < 0.01) of the cornea. The total corneal thickness and stromal thickness decreased significantly as well. No significant differences were observed between the postoperative and control cohorts. In conclusion, the FECD patients had an increased epithelial thickness compared to the healthy controls, which decreased significantly after DMEK and reached thickness levels comparable to those of healthy control eyes. This study emphasized the importance of distinguishing between the corneal layers in anterior segment pathologies and surgical procedures. Moreover, it accentuated the fact that the structural alterations in FECD extend beyond the corneal stroma.

Comparison of femtosecond laser-assisted cataract surgery and conventional phacoemulsification on corneal impact: A meta-analysis and systematic review

This meta-analysis aims to compare corneal injuries and function after femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification surgery (CPS). A comprehensive literature search of PubMed, EMBASE, and the Cochrane Controlled Trials Register was conducted to identify randomized controlled trials (RCT) and high-quality prospective comparative cohort studies comparing FLACS with CPS. Endothelial cell loss percentage (ECL%), central corneal thickness (CCT), endothelial cell density (ECD), endothelial cell loss (ECL), percentage of the hexagonal cell (6A), and coefficient of variance (CoV) were used as an indicator of corneal injury and function. Totally 42 trials (23 RCTs and 19 prospective cohort studies), including 3916 eyes, underwent FLACS, and a total of 3736 eyes underwent CPS. ECL% is significantly lower in the FLACS group at 1-3 days (P = 0.005), 1 week (P = 0.004), 1 month (P<0.0001), 3 months (P = 0.001), and 6 months (P = 0.004) after surgery compared to CPS. ECD and ECL appeared no statistically significant difference between the two groups, except for the significant reduction of ECD at 3 months in the CPS group (P = 0.002). CCT was significantly lower in the FLACS group at 1 week (P = 0.05) and 1 month (P = 0.002) early postoperatively. While at 1-3 days (P = 0.50), 3 months (P = 0.18), and 6 months (P = 0.11), there was no difference between the FLACS group and the CPS group. No significant difference was found in the percentage of hexagonal cells and the coefficient of variance. FLACS, compared with CPS, reduces corneal injury in the early postoperative period. Corneal edema recovered faster in the FLACS group in the early postoperative period. In addition, FLACS may be a better option for patients with corneal dysfunction.

Artificial Intelligence for Anterior Segment Diseases: A Review of Potential Developments and Clinical Applications

Artificial intelligence (AI) technology is promising in the field of healthcare. With the developments of big data and image-based analysis, AI shows potential value in ophthalmology applications. Recently, machine learning and deep learning algorithms have made significant progress. Emerging evidence has demonstrated the capability of AI in the diagnosis and management of anterior segment diseases. In this review, we provide an overview of AI applications and potential future applications in anterior segment diseases, focusing on cornea, refractive surgery, cataract, anterior chamber angle detection, and refractive error prediction.

Intergenic variants, rs1200114 and rs1200108 are genetically associated along with a decreased ATP1B1 expression in Fuchs Endothelial Corneal Dystrophy

Fuchs endothelial corneal dystrophy (FECD) is an age-related, bilateral corneal condition, characterized by apoptosis of the terminally differentiated endothelial cells. A genome-wide association study (GWAS) conducted in the European population in 2017, identified a new single nucleotide polymorphism (SNP), rs1200114 in the intergenic region between long intergenic non-protein coding RNA 970 (LINC00970) and ATPase Na+/K+ transporting subunit beta 1 (ATP1B1). The major focus of the current study is to understand the genetic association of this intergenic variant, rs1200114 with FECD in the Indian population. Sanger sequencing followed by statistical analysis indicated a significant difference in the allelic frequency between controls and cases (P = 0.01) with the minor allele 'G' of rs1200114 imparting a 1.64 fold increased risk for the disease. Luciferase reporter assay revealed no significant difference in the luciferase activity between allele 'A' and 'G' of rs1200114. However, quantitative RT-PCR assay revealed lower expression of ATP1B1 in FECD subjects compared with controls (P = 0.007). Therefore, to find whether another nearby SNP imparts regulatory effect, tag SNP association analysis was carried out; which revealed a significant association of another SNP, rs1200108, present in the intergenic region between LINC00970 and ATP1B1 with FECD (P = 0.009). The protective allele 'A' of rs1200108 displayed reduced reporter activity as opposed to the risk allele 'G' (P = 0.014). Furthermore, haplotype 'A-A' of rs1200108 - rs1200114 was present at a higher frequency in control subjects, suggesting it as a protective haplotype. Altogether, this study inferred the genetic association of rs1200114 and rs1200108 along with the decreased expression of ATP1B1 related to FECD pathogenesis in the Indian population.

Rescuing cellular function in Fuchs endothelial corneal dystrophy by healthy exogenous mitochondrial internalization

Fuchs endothelial corneal dystrophy (FECD) is characterized by an accelerated loss of corneal endothelial cells. Since the function of these cells is to maintain the cornea in a state of deturgescence necessary for its transparency, the depletion of corneal endothelial cells ultimately causes corneal edema and irreversible loss of vision. Evidence is accumulating regarding the central involvement of mitochondria in FECD. As we have previously shown, when endothelial cells die and are not replaced, the mitochondria of surviving cells must provide more energy to compensate, leading to a phenomenon we have called mitochondrial burnout. This burnout causes cell death, thus exacerbating an irreversible vicious circle responsible for FECD progression. Corneal transplantation, for which the transplant supply is insufficient, is the only curative alternative for FECD. It thus becomes imperative to find other avenues of treatment. In this article, we tested whether incorporating healthy mitochondria into FECD cells would improve pathological molecular markers of the disease. Using corneal endothelium explants from FECD patients, we demonstrated that incorporation of exogenous mitochondria into FECD cells by co-incubation reduces oxidative stress, increases mitochondrial membrane potential, and reduces mitophagy. In addition, internalization of exogenous mitochondria significantly reduces apoptosis (57% in FECD vs 12% in FECD with internalized mitochondria). Taken together, these results suggest that the internalization of exogenous mitochondria reverses the vicious circle involved in FECD, thus revealing a much-needed novel treatment alternative for FECD.

Anterior Corneal High-order Aberrations in Fuchs' Endothelial Corneal Dystrophy Classified by Scheimpflug Tomography

SIGNIFICANCE

Visual acuity may be limited after endothelial keratoplasty in Fuchs' endothelial corneal dystrophy. This may be due to increased anterior high-order aberrations that persist after endothelial keratoplasty. It is not clear at what stage these aberrations begin. We aimed to evaluate how subclinical corneal edema affects anterior corneal high-order aberrations.

PURPOSE

We aimed to evaluate anterior corneal high-order aberrations according to the presence of subclinical corneal edema in Fuchs' endothelial corneal dystrophy using Scheimpflug topography.

METHODS

All the patients underwent corneal topography (Sirius Scheimpflug-Placido disc camera; CSO Ophthalmic, Scandicci, Italy). Fifty-two eyes of 31 patients with Fuchs' endothelial corneal dystrophy and 52 eyes of 35 patients without corneal problems were included. In addition, patients with Fuchs' endothelial corneal dystrophy were divided into two groups according to subclinical corneal edema as with Fuchs' endothelial corneal dystrophy-edema and Fuchs' endothelial corneal dystrophy-nonedema. Subclinical corneal edema was defined based on the presence of at least two of three findings of the loss of regular isopachs, displacement of the thinnest point of the cornea, and posterior depression. High-order aberrations were expressed as Zernike polynomials in the 4- and 6-mm optical zone.

RESULTS

We found that subclinical corneal edema in Fuchs' endothelial corneal dystrophy caused a larger 4-mm trefoil II and a smaller 6-mm spherical aberration II measurements than the nonedema group. The 6-mm total high-order aberrations, 6-mm coma aberration, and 4- and 6-mm trefoil II aberration measurements were larger, and the 6-mm spherical aberration II was smaller in Fuchs' endothelial corneal dystrophy patients with edema compared with the healthy eyes.

CONCLUSIONS

The presence of subclinical corneal edema in Fuchs' endothelial corneal dystrophy results in larger 4-mm trefoil II and smaller 6-mm spherical aberration II measurements. More patients with intermediate values are needed to evaluate the effect of these aberrations on visual acuity.

Clinical outcomes of presbyopia-correcting intraocular lenses in patients with Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) is considered a contraindication for the implantation of presbyopia-correcting IOLs, without sufficient corroborating evidence. A Retrospective, case-control study. Nineteen eyes of ten patients with grade 2-5 FECD (study group) and 57 healthy eyes of 57 patients (control group) who underwent cataract surgery with implantation of presbyopia-correcting IOLs, at the Ein-Tal Eye Center, Tel Aviv, Israel, were included. The target refraction was emmetropia for both groups. Two subgroups of IOLs were analyzed separately: extended depth of focus (EDOF), (9 eyes of FECD patients and 27 eyes of control patients) and multifocal IOLs (10 eyes of FECD patients and 30 eyes of control patients). Main outcome measures were visual acuity and refraction 6 weeks after the surgery. Secondary outcomes were patient perceptions of visual acuity, spectacle independence, photic phenomena and satisfaction scores, reported in a self-assessment questionnaire. FECD patients in the EDOF IOL subgroup had inferior uncorrected distance visual acuity (P = 0.007) and better uncorrected near visual acuity (P = 0.001) compared to the controls. They had less spectacle independence for the intermediate range (P = 0.01) and overall (P = 0.006). However, they did not have more photic phenomena. In the multifocal IOL subgroup, no significant differences were found between the FECD and the control group in visual acuity for all ranges and in spectacle independence. FECD patients had more photic phenomena than the controls (P = 0.006), but it did not interfere with daily life activities. There was no difference in post-operative mean spherical equivalent, patient reported visual perception, and general satisfaction between FECD and control patients in both groups. Our results suggest that presbyopia-correcting IOLs can be carefully considered in patients with grade 2-5 FECD, with slightly inferior results compared with healthy eyes.

Evaluating Keratoplasty for Fuchs' Endothelial Corneal Dystrophy: A Literature Review

Fuchs' endothelial corneal dystrophy (FECD) is progressive corneal endothelium dysfunction, characterised by corneal oedema, and potential blindness if left untreated. Keratoplasty is the only definitive treatment to restore vision in FECD, with different surgical techniques being described. The corneal transplant has been described as the most commonly performed and most successful allogenic transplant globally; therefore, it is crucial to dissect it further since a large proportion of the population worldwide is likely to be impacted. We feel that an updated literature review is both very relevant and necessary at present and aim to amalgamate more recent data on the topic (including meta-analyses, systematic reviews, and randomised control trials (RCTs), among others). We acknowledge that the paucity of reliable data limits progress for FECD and that there are existing ethical complexities in performing prospective trials on patients.  Traditionally, the surgery for FECD was limited to penetrating keratoplasty (PK), yet recent developments have introduced more advanced procedures and adapted the existing ones, to provide treatment specific to the disease-affected corneal layers. The questions we will address encompass: how does the severity of FECD govern the treatment options available, what are the differences between PK and types of endothelial keratoplasty (EK), what are the expected clinical outcomes of each of these operations, what are the potential concerns with the idealistic descemetorhexis surgery, and what do we envisage for times to come? Besides this, novel minimally-invasive pharmacological techniques are now being trialled, such as Rho kinase (ROCK) inhibition and cultured endothelial cells (CECs), which may drastically improve the dependence on corneal donors. We examine and critically appraise the literature to explore the understanding of FECD, and the treatment options that exist: historically, currently, and those anticipated for the future.

Scheimpflug Versus Optical Coherence Tomography to Detect Subclinical Corneal Edema in Fuchs Endothelial Corneal Dystrophy

PURPOSE

The purpose of this research was to compare the ability of Scheimpflug and anterior segment optical coherence tomography (OCT) in detecting subclinical corneal edema in patients with Fuchs endothelial corneal dystrophy (FECD) without clinical corneal edema.

METHODS

In this single-center, consecutive case series, 47 eyes of 29 patients with FECD were analyzed. The main outcome measures were anterior/posterior keratometry and central/thinnest corneal thickness. The criteria for subclinical corneal edema were loss of regular isopachs, displacement of the thinnest point of the cornea, and presence of posterior surface depression. Tomographic analyses were performed using Scheimpflug imaging (Pentacam HR) and OCT (anterior segment swept-source optical coherence tomography).

RESULTS

The measurement of the continuous variables revealed a significant difference between the 2 devices. The anterior curvature was steeper and the posterior curvature was flatter when measured with OCT ( P < 0.001). The OCT showed a lower central corneal thickness and thinnest corneal thickness ( P < 0.001). The agreement between both devices to detect subclinical corneal edema was high. The interdevice reliability for loss of parallel isopachs as measured by Cohen kappa coefficient was 0.84; for the displacement of the thinnest point of the cornea, it was 0.6, and for the focal posterior corneal surface depression, it was 0.62. Subclinical corneal edema was detected in 72.3% of the patients with both devices. In only 2 cases (4.3%), subclinical corneal edema was detected by one of the devices.

CONCLUSIONS

Scheimpflug and OCT imaging were both able to detect tomographic patterns of subclinical corneal edema. Therefore, both devices can help decision-making, favoring early endothelial keratoplasty in symptomatic patients with FECD without clinical corneal edema.

Potential role of extracellular granzyme B in wet age-related macular degeneration and fuchs endothelial corneal dystrophy

Age-related ocular diseases are the leading cause of blindness in developed countries and constitute a sizable socioeconomic burden worldwide. Age-related macular degeneration (AMD) and Fuchs endothelial corneal dystrophy (FECD) are some of the most common age-related diseases of the retina and cornea, respectively. AMD is characterized by a breakdown of the retinal pigment epithelial monolayer, which maintains retinal homeostasis, leading to retinal degeneration, while FECD is characterized by degeneration of the corneal endothelial monolayer, which maintains corneal hydration status, leading to corneal edema. Both AMD and FECD pathogenesis are characterized by disorganized local extracellular matrix (ECM) and toxic protein deposits, with both processes linked to aberrant protease activity. Granzyme B (GrB) is a serine protease traditionally known for immune-mediated initiation of apoptosis; however, it is now recognized that GrB is expressed by a variety of immune and non-immune cells and aberrant extracellular localization of GrB substantially contributes to various age-related pathologies through dysregulated cleavage of ECM, tight junction, and adherens junction proteins. Despite growing recognition of GrB involvement in multiple age-related pathologies, its role in AMD and FECD remains poorly understood. This review summarizes the pathophysiology of, and similarities between AMD and FECD, outlines the current knowledge of the role of GrB in AMD and FECD, as well as hypothesizes putative contributions of GrB to AMD and FECD pathogenesis and highlights the therapeutic potential of pharmacologically inhibiting GrB as an adjunctive treatment for AMD and FECD.

DenseUNets with feedback non-local attention for the segmentation of specular microscopy images of the corneal endothelium with guttae

Corneal guttae, which are the abnormal growth of extracellular matrix in the corneal endothelium, are observed in specular images as black droplets that occlude the endothelial cells. To estimate the corneal parameters (endothelial cell density [ECD], coefficient of variation [CV], and hexagonality [HEX]), we propose a new deep learning method that includes a novel attention mechanism (named fNLA), which helps to infer the cell edges in the occluded areas. The approach first derives the cell edges, then infers the well-detected cells, and finally employs a postprocessing method to fix mistakes. This results in a binary segmentation from which the corneal parameters are estimated. We analyzed 1203 images (500 contained guttae) obtained with a Topcon SP-1P microscope. To generate the ground truth, we performed manual segmentation in all images. Several networks were evaluated (UNet, ResUNeXt, DenseUNets, UNet++, etc.) and we found that DenseUNets with fNLA provided the lowest error: a mean absolute error of 23.16 [cells/mm[Formula: see text]] in ECD, 1.28 [%] in CV, and 3.13 [%] in HEX. Compared with Topcon's built-in software, our error was 3-6 times smaller. Overall, our approach handled notably well the cells affected by guttae, detecting cell edges partially occluded by small guttae and discarding large areas covered by extensive guttae.

Beneficial Effects of Polydeoxyribonucleotide (PDRN) in an In Vitro Model of Fuchs Endothelial Corneal Dystrophy

Fuchs endothelial corneal dystrophy (FECD) is a bilateral, hereditary syndrome characterized by progressive irreversible injury in the corneal endothelium; it is the most frequent cause for corneal transplantation worldwide. Oxidative stress induces the apoptosis of corneal endothelial cells (CECs), and has a crucial function in FECD pathogenesis. The stimulation of the adenosine A_2A receptor (A_2Ar) inhibits oxidative stress, reduces inflammation and modulates apoptosis. Polydeoxyribonucleotide (PDRN) is a registered drug that acts through adenosine A_2Ar. Thus, the goal of this study was to assess the effect of PDRN in an in vitro FECD model. Human Corneal Endothelial Cells (IHCE) were challenged with H₂O₂ (200 μM) alone or in combination with PDRN (100 μg/mL), PDRN plus ZM241385 (1 μM) as an A_2Ar antagonist, and CGS21680 (1 μM) as a well-known A_2Ar agonist. H₂O₂ reduced the cells’ viability and increased the expression of the pro-inflammatory markers NF-κB, IL-6, IL-1β, and TNF-α; by contrast, it decreased the expression of the anti-inflammatory IL-10. Moreover, the pro-apoptotic genes Bax, Caspase-3 and Caspase-8 were concurrently upregulated with a decrease of Bcl-2 expression. PDRN and CGS21680 reverted the negative effects of H₂O₂. Co-incubation with ZM241385 abolished the effects of PDRN, indicating that A_2Ar is involved in the mode of action of PDRN. These data suggest that PDRN defends IHCE cells against H₂O₂-induced damage, potentially as a result of its antioxidant, anti-inflammatory and antiapoptotic properties, suggesting that PDRN could be used as an FECD therapy.

Cost Burden of Endothelial Keratoplasty in Fuchs Endothelial Dystrophy: Real-World Analysis of a Commercially Insured US Population (2014–2019)

Purpose

To assess the incremental burden of corneal transplant surgery for US commercially insured patients with Fuchs endothelial corneal dystrophy (FECD) treated with endothelial keratoplasty (EK) compared to controls.

Methods

The study design was retrospective cohort using IBM^® MarketScan^® claims (January 2014–September 2019) and included EK-treated (N=1562) and control patients (N=23,485) having ≥12 months’ enrollment before and after diagnosis, who were subsequently matched on select characteristics. The index date was the beginning of the pre-operative period (3 months before EK); synthetic EK index was assigned for controls. All-cause, eye-disease, and complication-related healthcare resource utilization (HCRU) and costs were compared up to 36 months post index. For a small subset of patients, patient data were linked to the Health and Productivity Management supplemental database, which integrates data on productivity loss and disability payments.

Results

Matched cohorts included 804 EK-treated and 1453 controls with average age 65.7 years, 1383 (61%) female. Over 12 months of follow-up, all-cause ($41,199 vs $20,222, p<0.001) and eye-disease related costs ($22,951 vs $1389, p<0.001) were higher among EK-treated patients than controls. The cost differential increased additionally by $1000–$2000 per annum by 36 months of follow-up. While balanced at baseline, over follow-up EK-treated patients had higher prevalence of glaucoma, elevated intraocular pressure, cataract, cataract surgery, diagnosis of cornea transplant rejection, retinal edema. By 36 month of follow-up, EK-treated patients had 9 more short-term disability days, resulting in $2992 additional burden of disability payments.

Conclusion

This study found a higher cost burden among FECD patients receiving EK treatment versus those who did not. With a shift in management of FECD, cost burden estimates generated in this study could serve as an important benchmark for future studies.

Tissue engineered scaffolds for corneal endothelial regeneration: a material's perspective

Currently, the treatment of corneal diseases caused by damage to the corneal endothelium requires a donor cornea. Because of their limited availability (1 donor cornea for 70 patients in need), researchers are investigating alternative approaches that are independent of donor tissue. One of them includes the development of a tissue engineered scaffold onto which corneal endothelial cells are seeded. In order to function as a suitable substrate, some of its essential properties including thickness, permeability, transparency and mechanical strength should meet certain demands. Additionally, the membrane should be biocompatible and allow the formation of a functional endothelium on the surface. Many materials have already been investigated in this regard including natural, semi-synthetic and synthetic polymers. In the current review, we present an overview of their characteristics and provide a critical view on the methods exploited for material characterization. Next, also the suitability of scaffolds to serve their purpose is discussed along with an overview of natural tissues (e.g. amniotic membrane and lens capsule) previously investigated for this application. Eventually, we propose a consistent approach to be exploited ideally for membrane characterization in future research. This will allow a scientifically sound comparison of materials and membranes investigated by different research groups, hence benefitting research towards the creation of a suitable/optimal tissue engineered endothelial graft.

Identification of novel therapeutic targets for Fuchs' endothelial corneal dystrophy based on gene bioinformatics analysis

Fuchs' endothelial corneal dystrophy (FECD) is a disease where progressive visual impairment occurs by the thickening of the Descemet's membrane and the gradual degeneration and loss of corneal endothelial cells. This study aimed to investigate the key changes in gene expression associated with FECD and explore potential biomarkers and new therapeutic strategies for FECD. To explore the potential therapeutic targets of FECD, we downloaded the gene expression dataset GSE171830 from the Gene Expression Omnibus (GEO) database. A total of 303 differentially expressed genes (DEGs) were identified by the limma package. The enriched Gene Ontology (GO) annotations and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of DEGs mostly included the extracellular matrix organization, collagen-containing extracellular matrix, and the structural constituents of the extracellular matrix. Fifteen hub genes from the most significant module were ascertained by Cytoscape. Both collagen-containing extracellular matrix and extracellular matrix hit to ANXA1, VCAN, GPC3, TNC, IGFBP7, MATN3, and SPARCL1 genes in the GO cellular components. Among these genes, the expression of SPARCL1 was down-regulated in the FECD samples, whereas the expression of GPC3, MATN3, IGFBP7, TNC, VCAN, and ANXA1 was up-regulated in the FECD samples. Gene set enrichment analysis (GSEA) plots showed that among the 20,937 genes, SPARCL1 played an important role in three pathways, cytokine-cytokine receptor interaction, the TGF-beta signaling pathway, and antigen processing and presentation. The top three pathways enriched by the GPC3, MATN3, IGFBP7, TNC, VCAN, and ANXA1 genes were those for cytokine-cytokine receptor interaction, TGF-beta signaling, and RIG-I-like receptor signaling. In conclusion, the DEGs identified here might assist clinicians in understanding the pathogenesis of FECD. Furthermore, these identified biomarkers might serve as potential therapeutic targets for the treatment of FECD.

The Sociodemographic and Risk Factors for Fuchs’ Endothelial Dystrophy: A Nationwide, Matched Case–Control Study in Taiwan

This nationwide, population-based, retrospective, matched case–control study included 4334 newly diagnosed Fuchs’ endothelial dystrophy (FED) patients who were identified by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), code 371.57, and selected from the Taiwan National Health Insurance Research Database. The age-, sex-, and index-date-matched control group included 4334 non-FED controls selected from the Taiwan Longitudinal Health Insurance Database 2000. Ocular allergic conditions and sociodemographic conditions were examined using univariate logistic regression analyses and paired t-test was used for continuous variables. Adjusted logistic regression was used to compare the odds ratio (OR) of the FED development. Patients with ocular allergic conditions were more likely to have FED than the controls (OR = 25.50, 95% CI = 12.58–51.68, p < 0.0001) even after conditional logistic regression was conducted (adjusted OR = 25.26, 95% CI = 11.24–56.77, p < 0.0001). Regarding the sociodemographic factors, we found that more than half of the FED patients in Taiwan were aged ≥45 years old, there was an equal female-to-male ratio (1.06:1), and patients with a lower income and living in northern Taiwan had higher odds of developing FED. The results strongly support an association between ocular allergic conditions, geographic region, residential status, income, and FED.

Clinical, Morphological, and Optical Correlates of Visual Function in Patients With Fuchs Endothelial Corneal Dystrophy

PURPOSE

The purpose of this article was to study the clinical, optical, and morphological correlates of visual function in patients with Fuchs endothelial corneal dystrophy (FECD).

METHODS

The case records were analyzed for patients diagnosed with FECD between September 2019 and March 2020. The best-corrected visual acuity (BCVA) was recorded as decimal visual acuity and converted to the logarithm of the minimum angle of resolution units. Contrast sensitivity was measured with the Pelli-Robson contrast sensitivity test. Corneal alterations, including central corneal thickness, depression of the posterior cornea, and corneal densitometry values, were evaluated using Scheimpflug images. Corneal epithelial thickness was measured by spectral-domain optical coherence tomography.

RESULTS

A total of 107 eyes of 61 patients (18 male and 43 female) with FECD were retrospectively investigated. The Spearman rank correlation coefficient showed moderate correlation between BCVA and contrast sensitivity (ρ = -0.66, P < 0.001), with some patients maintaining relatively good BCVA but having reduced contrast sensitivity. Logistic regression analysis demonstrated that age, central corneal thickness, depression of the posterior cornea, and epithelial thickening were negatively associated with contrast sensitivity but not with BCVA.

CONCLUSIONS

Contrast sensitivity is a useful tool for assessing visual dysfunction and should be incorporated into the assessment protocol of patients with FECD. Alterations in the cornea, including central corneal thickness, depression of the posterior cornea, and epithelial thickening, might be objective parameters that can help the clinician in grading the severity of the disease and tracking its progression.