Hyperglycemia-depleted glutamine contributes to the pathogenesis of diabetic corneal endothelial dysfunction

Diabetic mellitus (DM) causes various complications, including the corneal endothelial dysfunction that leads to corneal edema and vision loss, especially in the DM patients with intraocular surgeries. However, the pathogenic mechanism of hyperglycemia-caused corneal endothelial dysfunction remains incomplete understood. Here we firstly screened and identified the glutamine contents of aqueous humor (AH) were significantly reduced in the type 2 diabetic patients and type 1 and type 2 diabetic mice. To explore the potential therapeutic effects of glutamine (Gln) supplement on the protection of diabetic corneal endothelial dysfunction, we performed the anterior chamber perfusion with the addition of L-alanyl-L-glutamine (Ala-Gln), and confirmed that Ala-Gln supplement not only accelerated the resolution of corneal edema and recovery of corneal thickness, but also preserved the regular arrangement and barrier-pump function of cornea. Mechanistically, we revealed that the supplements of Ala-Gln protect corneal endothelial cells (CECs) from the deleterious effects of high glucose-induced oxidative stress, mitochondrial dysfunction, and cell apoptosis. Overall, these results indicate the Gln depletion plays an important role in the diabetic corneal endothelial dysfunction, while the Ala-Gln supplement during intraocular surgery provide an effective prevention strategy through regulating the redox homeostasis and mitochondrial function of corneal endothelium.

Associations between endothelial cell characteristics and corneal topography findings in different stages of keratoconus

PURPOSE

This study aimed to compare and correlate specular microscope indices and corneal topography indices in different stages of keratoconus.

METHODS

Two hundred forty-six eyes of 123 participants were enrolled in the study. Corneal topography was performed using Sirius (CSO, Italy), with a rotating Scheimpflug camera and a Placido disc topographer. Corneal endothelial cell indices were assessed using a specular microscope (Nidek CEM-530, Japan). Eyes were graded as keratoconus stages 0-4 according to the Amsler-Krumeich classification. Corneal topography and endothelial cell indices were compared among the groups, and the correlations between them were analyzed.

RESULTS

The mean age of the patients was 23.26 ± 6.75 years (range, 14-47 years). Forty-eight cases were male (39%) and 75 were female (61%). There were no statistically significant age (p = 0.578) or sex ratio (p = 0.529) differences between the groups. Twenty-nine eyes were included in the control group (11.78%), while 41 (16.67%) had stage 1 keratoconus, 88 (35.77%) had stage 2, and 88 (35.77%) had stage 3. Measurement was not possible in stage 4 keratoconus. No statistically significant difference was determined in specular microscopy values according to the stage of keratoconus, except for the number of analyzed cells (NUM) (p > 0.05). The lowest NUM values were observed in stages 1, 2, and 3, with values of 184.34 ± 67.62 cells/mm2, 155.07 ± 59.48 cells/mm2, and 127.06 ± 64.39 cells/mm2, respectively (p = 0.001). In the keratoconus group, weak statistically significant negative correlations were observed between NUM and SimK1, SimK2, KVf, BCVf, KVb, and BCVb, while a weak positive correlation was noted between NUM and central corneal thickness (p < 0.05).

CONCLUSIONS

NUM seems to decrease, while endothelial cell density exhibits no significant changes, with the progression of keratoconus. It appears that as keratoconus index values increase, NUM may decrease in different stages of keratoconus.

[Innovative surgical treatment approaches for endothelial dysfunction : Descemet stripping only (DSO) and endothelial cell injection]

Currently, due to a rising number of patients Germany and many other countries experience a large deficit of donor eyes for posterior lamellar keratoplasty procedures in the treatment of corneal endothelial diseases. To address this unmet need there is an ongoing investigation of treatment modalities which do not rely on donor tissue or enable clinicians to treat more patient eyes per donor eye. The authors introduce a promising approach for both treatment principles. First, the technique of Descemet stripping only (DSO) is detailed, in which a central part of the Descemet's membrane including the endothelium is surgically removed without replacement with donor tissue. This then allows endothelial cells from the periphery of the cornea to migrate into the central area and can reduce corneal opacification and swelling. As a representative technique of the second group, the authors introduce endothelial cell injection, in which human corneal endothelial cells are cultivated in vitro and then, after removal of the diseased endothelium, injected into the anterior chamber of the recipient's eye to form a new and healthy endothelium. This is supported by injection of Rho kinase inhibitors and a face-down positioning of the patient after surgery. It is postulated that endothelial cell injection could possibly enable clinicians to treat up to 300 patient eyes with the tissue generated from 1 donor eye. Whether and how these novel approaches will become established in Europe remains to be seen.

[Pathogenesis of Fuchs endothelial corneal dystrophy, the fibrillar layer and individualized treatment]

Fuchs endothelial corneal dystrophy (FECD) is a genetic and age-associated corneal disease characterized by an accelerated loss of corneal endothelial cells and an increased subendothelial deposition of extracellular matrix (ECM). Clinically, advanced disease leads to corneal edema with subsequent reduction in visual acuity. In the majority of patients with advanced FECD, a fibrillar layer (FL) appears on the posterior corneal surface. This FL is mostly localized in the inferotemporal corneal quadrant, marks areas with significantly reduced endothelial cell density and increased corneal thickness in the sense of edema and can be visualized and measured using Scheimpflug backscatter analysis due to increased backscatter. FECD is currently the most common indication for corneal transplantation worldwide, usually in the form of Descemet membrane endothelial keratoplasty (DMEK). New treatment approaches include variations of DMEK surgery such as hemi- or quarter DMEK with individualized and smaller grafts or Descemet membrane stripping only (DSO). In the future, clinical imaging of the FL as a particularly affected endothelial area could be important for FECD progression assessment and planning of surgical interventions. This article provides an overview of the current state of research on the clinical aspects, pathogenesis, fibrillar layer and individualized treatment 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.

TCF4 trinucleotide repeat expansions and UV irradiation increase susceptibility to ferroptosis in Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD), the leading indication for corneal transplantation in the U.S., causes loss of corneal endothelial cells (CECs) and corneal edema leading to vision loss. FECD pathogenesis is linked to impaired response to oxidative stress and environmental ultraviolet A (UVA) exposure. Although UVA is known to cause nonapoptotic oxidative cell death resulting from iron-mediated lipid peroxidation, ferroptosis has not been characterized in FECD. We investigated the roles of genetic background and UVA exposure in causing CEC degeneration in FECD. Using ungenotyped FECD patient surgical samples, we found increased levels of cytosolic ferrous iron (Fe2+) and lipid peroxidation in end-stage diseased tissues compared with healthy controls. Using primary and immortalized cell cultures modeling the TCF4 intronic trinucleotide repeat expansion genotype, we found altered gene and protein expression involved in ferroptosis compared to controls including elevated levels of Fe2+, basal lipid peroxidation, and the ferroptosis-specific marker transferrin receptor 1. Increased cytosolic Fe2+ levels were detected after physiologically relevant doses of UVA exposure, indicating a role for ferroptosis in FECD disease progression. Cultured cells were more prone to ferroptosis induced by RSL3 and UVA than controls, indicating ferroptosis susceptibility is increased by both FECD genetic background and UVA. Finally, cell death was preventable after RSL3 induced ferroptosis using solubilized ubiquinol, indicating a role for anti-ferroptosis therapies in FECD. This investigation demonstrates that genetic background and UVA exposure contribute to iron-mediated lipid peroxidation and cell death in FECD, and provides the basis for future investigations of ferroptosis-mediated disease progression in FECD.

Neuropeptide alpha-Melanocyte stimulating hormone preserves corneal endothelial morphology in a murine model of Fuchs dystrophy

Fuchs endothelial corneal dystrophy is a heterogenous disease with multifactorial etiology, and genetic, epigenetic, and exogenous factors contributing to its pathogenesis. DNA damage plays a significant role, with ultraviolet-A (UV-A) emerging as a key contributing factor. We investigate the potential application of neuropeptide α-melanocyte stimulating hormone (α-MSH) in mitigating oxidative stress induced endothelial damage. First, we examined the effects of α-MSH on a cultured human corneal endothelial cell line (HCEnC-21T) exposed to hydrogen peroxide (H2O2) induced oxidative DNA damage. We performed immunofluorescence and flow cytometry to assess DNA damage and cell death in the cultured cells. Additionally, we used an established mouse model that utilizes ultraviolet light to induce corneal endothelial cell damage resulting in decreased CEnC number, increased cell size variability, and decreased percentage of hexagonal cells. This endothelial decompensation leads to an increase in corneal thickness. Following UV-A exposure, the mice were systemically treated with α-MSH, either immediately after exposure (early treatment) or beginning two weeks post-exposure (delayed treatment). To evaluate treatment efficacy, we analyzed CEnC density and morphology using in vivo confocal microscopy, and central corneal thickness using anterior segment optical coherence tomography. Our findings demonstrated that α-MSH treatment effectively protects HCEnC-21T from free-radical induced oxidative DNA damage and subsequent cell death. In vivo, α-MSH treatment, mitigated the loss of CEnC density, deterioration of cell morphology and suppression of the resultant corneal swelling. These results underline the potential application of α-MSH as a therapeutic agent for mitigating corneal endothelial damage.

Correlation between corneal endothelial layer features and age-related macular degeneration severity

PURPOSE

This study aimed to investigate the relationship between corneal endothelial layer features and the severity of age-related macular degeneration (AMD).

METHODS

The study included 119 patients, with 47 females and 72 males. Patients were categorized into four groups based on the AREDS grading system: no AMD (group 1), mild AMD (group 2), moderate AMD (group 3), and advanced AMD (group 4). Only the right eye of patients with both eyes suitable for the study was included. Corneal endothelial cell density (CD), coefficient of variation (CoV), hexagonal cell ratio (HEX), and central corneal thickness (CCT) were measured using specular microscopy (Konan Medical Inc., Nishinomiya, Japan).

RESULTS

Group 1 had 40 patients, group 2 had 27 patients, and groups 3 and 4 had 26 patients each. Significant differences were observed between the mean endothelial CD, CoV, and HEX values among the groups, while no significant difference was found in CCT values (p = 0.049, p = 0.002, p = 0.004, and p = 0.883, respectively). A mild negative correlation was observed between AMD severity and CD and HEX values, while a mild positive correlation was found between AMD severity and CoV.

CONCLUSION

Increasing severity of AMD may negatively impact corneal endothelial layer values.

Sleep deprivation induces corneal endothelial dysfunction by downregulating Bmal1

BACKGROUND

Sleep deprivation (SD) is a common public health problem that contributes to various physiological disorders and increases the risk of ocular diseases. However, whether sleep loss can damage corneal endothelial function remains unclear. This study aimed to determine the effect and possible mechanism of SD on the corneal endothelium.

METHODS

Male C57BL/6J mice were subjected to establish SD models. After 10 days, quantitative RT-PCR (qRT-PCR) and western blot or immunostaining for the expression levels of zonula occludens-1 (ZO-1), ATPase Na+/K + transporting subunit alpha 1 (Atp1a1), and core clock genes in the corneal endothelium were evaluated. Reactive oxygen species staining and mitochondrial abundance characterized the mitochondrial function. The regulatory role of Bmal1 was confirmed by specifically knocking down or overexpressing basic helix-loop-helix ARNT like 1 protein (Bmal1) in vivo. In vitro, a mitochondrial stress test was conducted on cultured human corneal endothelial cells upon Bmal1 knockdown.

RESULTS

SD damaged the barrier and pump functions of mouse corneal endothelium, accompanied by mitochondrial dysfunction. Interestingly, SD dramatically downregulated the core clock gene Bmal1 expression level. Bmal1 knockdown disrupted corneal endothelial function, while overexpression of Bmal1 ameliorated the dysfunction induced by SD. Mitochondrial bioenergetic deficiency mediated by Bmal1 was an underlying mechanism for SD induced corneal endothelial dysfunction.

CONCLUSION

The downregulation of Bmal1 expression caused by SD led to corneal endothelial dysfunction via impairing mitochondrial bioenergetics. Our findings offered insight into how SD impairs the physiological function of the corneal endothelium and expanded the understanding of sleep loss leading to ocular diseases.

Determination of progressive endothelial cell loss after posterior chamber phakic intraocular lens implantation

Comments about endothelial cell loss after posterior chamber phakic intraocular lens are provided, with a particular emphasis on the importance of determining progressive postoperative cell density reduction, excluding that related to surgical trauma.

Aqueous Humor Circulation in the Era of Minimally Invasive Surgery for Glaucoma

Glaucoma surgery with implantation of aqueous humor draining microstents may compromise long-term corneal health by disrupting aqueous humor circulation. The effect of stent numbers on this circulation was interrogated to determine the number of stents associated with minimal circulation disruption. An in vitro anterior eye model perfusion system was constructed with multiple exit ports. A 3-D model of the anterior eye was imported into ABAQUS CFD, analyzes were carried out for unsteady laminar flow and solved using Navier-Stokes equations. DT Vision Foundry was used to analyze velocity contour plot images. The field variable results output for the CFD model were fluid wall shear, fluid pressure and fluid velocity. In vitro, "aqueous" fluid flow is high through a single stent and "aqueous" stagnation is greatest in the quadrants 180° away. Increasing stent port numbers, results in an exponential decrease in the stagnant flow locations. High wall shear stress was seen in the single stent model and is markedly reduced after a second and subsequent stents are introduced. We identify two factors potentially contributing to corneal compromise post glaucoma drainage surgery: aqueous humor stagnation, remote to the stent site and higher exit flows imparting increased stent exit shear stress (particularly with a single stent). With 4 stents, there is minimal disruption of anterior chamber circulation (mimicking physiological conditions). Furthermore we propose that aqueous humor circulation disruption via the usual single-exit port approach disrupts aqueous humor circulation with long-term consequences for corneal health.

COVID-19 related changes in corneal curvature and endothelium after mild infection

PURPOSE

To investigate subclinical corneal changes using corneal topography in the evaluation of corneal curvature and specular microscopy in the evaluation of the endothelial layer after mild coronavirus disease 2019 (COVID-19).

METHODS

In this prospective study, 112 eyes of 56 individuals with mild COVID-19 who recovered were investigated. Mean cell density (CD), mean coefficient of variation (CV), mean percentage of hexagonal cells, mean cell area (AVG), and central corneal thickness (CCT) were recorded from specular microscopy. K readings, including simulated keratometry flat (K1), simulated keratometry steep (K2), average keratometry (Kmean) and maximum keratometry (Kmax), pachymetric measurement and central corneal thickness (CCT), corneal volume (CV), topographic astigmatism (TA), curvature asymmetry front (CAf) and curvature asymmetry back (CAb) were recorded from corneal topography. Best corrected visual acuity (BCVA), spherical equivalant and biometric measurements were recorded.

RESULTS

The mean time interval between examinations before and after COVID-19 infection was approximately one year. Analysis of specular microscopy data showed a statistically significant change in all endothelial cell parameters (p<0.001) except the cell count (p = 0.358). The median (range) endothelial cell density (ECD) value was significantly lower after COVID-19 at 2356 (2289-2400) than before, when it was 2596 (2545-2640). Furthermore, CCT values showed a significant increase (p<0.001). The topographic values including K2, Kmax and TA and biometric measurements did not change. The Spherical Equivalant (SE) values showed significant myopic progression after COVID-19 (p<0.001).

CONCLUSION

Endothelial parameters changed more than the changes in corneal curvature and ocular biometric measurements after mild COVID-19. The decrease in endothelial cell number and hexagonality and increase in polymorphism after COVID-19 were striking.

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

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

Enhancing Visual Acuity through Combined Intraocular Lens Fixation, Penetrating Keratoplasty, and Vitrectomy: The Role of Temporary Landers Wide-Field Keratoprosthesis

Introduction

Complex corneal conditions present surgical challenges and necessitate innovation. Here, we present two cases where we performed intraocular lens trans-scleral fixation using the double-needle Yamane technique, followed by penetrating keratoplasty and vitrectomy using a temporary Landers wide-field keratoprosthesis.

Case Presentation

Case 1 involved a 70-year-old man with an aphakic eye of bullous keratopathy and corneal opacity owing to multiple penetrating and endothelial keratoplasty, endophthalmitis, and herpetic keratitis. His visual acuity was counting fingers at 20 cm before surgery. Penetrating keratoplasty with vitrectomy and intraocular lens scleral fixation was performed using the double-needle Yamane technique, and 10 months postoperatively, his best-corrected visual acuity improved to 0.6, presenting a clear cornea. Case 2 involved a 62-year-old man who underwent penetrating keratoplasty twice for corneal perforation and therapeutic penetrating keratoplasty with vitrectomy for traumatic globe rupture, resulting in the loss of the intraocular lens. The patient exhibited graft failure, and his best-corrected visual acuity was 0.03. Utilizing a temporary Landers wide-field keratoprosthesis, we performed penetrating keratoplasty and intraocular lens trans-scleral fixation without complications. His final best-corrected visual acuity improved to 0.15 with a clear cornea.

Conclusions

Trans-scleral fixation of intraocular lens with penetrating keratoplasty, using temporary Landers wide-field keratoprosthesis, yielded positive clinical outcomes without serious complications.

A Case of Transparent Cornea Maintained after Removal of Dislocated Graft from Descemet's Stripping Automated Endothelial Keratoplasty

Introduction

Corneal graft detachment is a major postoperative complication of Descemet's stripping automated endothelial keratoplasty (DSAEK). When a corneal graft becomes detached, corneal endothelial function generally fails, and repeat corneal transplantation is required. Herein, we report a rare case in which a transparent cornea was maintained after the removal of a dislocated DSAEK graft.

Case Presentation

A 79-year-old woman with a residual lens cortex who had undergone cataract surgery was referred to our hospital. The cortex was removed, and bullous keratopathy progressed. Six months after the initial surgery, DSAEK was performed under topical anesthesia without any complications. Although the corneal graft had attached fairly well, it detached from the host cornea 3 weeks later. Two months after DSAEK, an air tamponade was used to treat the anterior chamber with single interrupted suturing; however, the graft detached again, except for the suture site. Because the detached cornea became cloudy in the anterior chamber, it was surgically removed 8 months after DSAEK. Accordingly, the host cornea transparency improved to a best-corrected visual acuity of 0.8 with a rigid gas permeable lens and a central corneal thickness of 580 μm. The corneal endothelial cell density was 995 cells/mm2.

Conclusion

Removal of the corneal graft from the dislocated cloudy graft improved the visual acuity of this patient after DSAEK. The condition of the cornea should be carefully monitored after corneal endothelial transplantation, even after the graft has been dislocated.

Evaluation of the corneal thickness and endothelial changes following uncomplicated phacoemulsification in diabetic and non-diabetic patients with pseudo-exfoliation syndrome by specular microscopy

PURPOSE

To evaluate corneal endothelial cell changes following uncomplicated phacoemulsification in diabetic patients with PEX, compared with diabetic patients and non-diabetic patients with PEX.

METHODS

This prospective, comparative, non-randomized cohort study included 61 eyes of 61 patients who were diagnosed as having senile cataract. Patients were divided into three groups: Group (1) included 19 eyes of patients with DM and PEX, group (2) included 22 eyes of diabetic patients, and group (3) included 20 eyes of patients with PEX. All included patients had uncomplicated phacoemulsification with IOL implantation. Patients were examined by non-contact specular microscopy (NIDEK, CEM-530, Japan), preoperatively and postoperatively at regular follow-up periods (one, three, and six months postoperatively) with analysis of the endothelial cell density, percentage of hexagonal cells, CV, and CCT.

RESULTS

By the end of follow-up period, there was a statistically significant reduction in ECD and HEX with a significant increase in CV and CCT in group one (DM-PEX). In group two (DM), a statistically significant decrease in ECD and HEX with a significant increase in CCT was reported, while in group three (PEX), the only significant difference was found in the form of ECD reduction.

CONCLUSION

Patients with DM and PEX had significant changes regarding ECD, CV, HEX, and CCT which were more pronounced than in patients with DM only or PEX only. More attention should be paid while operating on diabetic patients with PEX to save corneal endothelium and decrease postoperative complications.

STUDY REGISTRATION NUMBER

The study was retrospectively registered (16 July 2021) on ClinicalTrials.gov (NCT04965168).

Integrative analysis of gene expression datasets in corneal endothelium samples of Fuchs endothelial corneal dystrophy

FECD is an age-related progressive ocular disorder characterized by the gradual loss of corneal endothelial cells. Although the exact pathogenesis of FECD remains incompletely understood, differentially expressed genes in the corneal endothelium of FECD patients compared to controls have been reported in several studies. However, a consensus regarding consistently affected genes in FECD has not been established. To address this issue, we conducted a comprehensive meta-analysis incorporating five studies with data that met our predefined inclusion criteria. The combined dataset included 41 FECD patients and 26 controls. We conducted study-level analyses, followed by a meta-analysis, and subsequent functional enrichment analysis targeting the topmost DEGs. Our findings revealed a total of 1537 consistently dysregulated genes in the corneal endothelium of FECD patients. Notably, only 14.6% (224/1537) of these DEGs had been previously identified as statistically significant in individual datasets. Functional enrichment analysis revealed that the upregulated DEGs were significantly enriched in immune-related signaling pathways, with a particularly high enrichment in "The NLRP3 inflammasome" and "Inflammasomes" pathways. In conclusion, we successfully identify a set of consistently dysregulated genes in FECD, which are associated with both established and novel biological pathways. This study highlights the importance of further investigating the role of inflammasomes in FECD pathogenesis and exploring strategies to modulate inflammasome activation for the management of this debilitating condition.

Iris-Claw Anterior Chamber Phakic Intraocular Lens Explantation: A Case Series

Purpose

To evaluate indications, clinic characteristics, and outcomes in a series of patients who underwent explantation of phakic intraocular lens (pIOL).

Methods

Retrospective case series of patients who underwent iris-claw pIOL explantation in our institution from 2018 to 2022. Indications for explantation and visual and refractive outcomes were analyzed.

Results

Twenty-three eyes of 14 patients underwent pIOL explantation with a mean time to explantation of 11.7 ± 3.4 years. The mean age at explantation was 46.0 ± 3.9 years. Sixteen Artisan and seven Artiflex IOL were explanted. The main indication for explantation was endothelial cell loss (n = 14) and morphometric significant alterations of endothelial cells other than endothelial cell count decline (n = 5). The mean corrected vision after explantation was 0.4 ± 0.4 logMAR, and around 70% of intervened patients achieved visual acuity of at least 0.3 logMAR (0.5 in decimal scale).

Conclusions

In our group series, the main reason for the removal of pIOL was endothelial cell loss. This complication should be monitored and followed, so that early actions, namely IOL explantation, can be performed to avoid the development of deterioration requiring corneal transplantation. In fact, loss of follow-up, found in several cases for many years, continues to be a serious problem.

Factors associated with severe corneal endothelial damage following acute primary angle closure in Chinese subjects

PURPOSE

To investigate the corneal endothelial damage caused by acute primary angle closure (APAC) and related risk factors for severe corneal endothelial cell damage in Chinese subjects.

METHODS

In this multicentre retrospective study, 160 Chinese patients (171 eyes) diagnosed with APAC were recruited. Endothelial cell density (ECD) and morphological changes short after APAC were studied. Univariate regression and multivariate regression were used to identify risk factors associated with the extent of ECD reduction, including age, gender, education level, patients' location, systemic diseases, APAC duration (hours), highest recorded intraocular pressure (IOP), and presenting IOP. Factors associated with the probability of severe corneal damage (ECD lower than 1000/mm2) were analysed based on a linear function.

RESULTS

After one APAC episode, 12.28% eyes had ECD lower than 1000/mm2, 30.41% had ECD between 1000 and 2000/mm2, and 57.31% had ECD more than 2000/mm2. Attack duration was the only factor associated with severe endothelial damage (p < 0.0001). If the attack were to be subsided within 15.0 h, possibility of ECD lower than 1000/mm2 could be controlled under 1%.

CONCLUSION

Shortly after the abortion of APAC, 12.28% patients experienced severe endothelial cell damage with ECD less than 1000/mm2. The only factor associated with severe ECD decrease was attack duration. Immediate and effective treatment is pivotal for preserving corneal endothelial function in APAC patients.

Evaluation of scleral thickness in patients with Fuchs endothelial dystrophy

PURPOSE

To evaluate scleral thickness using anterior segment-optical coherence tomography (AS-OCT) in Fuchs endothelial dystrophy (FED) and compare the results with healthy individuals.

METHODS

Thirty-two eyes of 32 patients with FED and 30 eyes of 30 age, gender, spherical equivalent and axial length matched healthy participants were included. All subjects underwent a detailed ophthalmological examination including endothelial cell density and central corneal thickness (CCT) measurements. Scleral thickness was measured by AS-OCT (Swept Source-OCT, Triton,Topcon,Japan) in 4 quadrants (superior, inferior, nasal, temporal) from 6 mm posterior to the scleral spur.

RESULTS

The mean ages were 62.5 ± 13.2 (33-81) for FED group; 64 ± 8.1 (48-81) for control group. CCT was significantly greater in FED group than in the control group (586.8 ± 33.1 (514-635) vs 545.0 ± 20.7 (503-587), respectively)(p = 0.000). In FED group, mean scleral thickness in the superior, inferior, nasal and temporal quadrants were 434.0 ± 30.6 (371-498), 442.8 ± 27.6 (395-502), 447.7 ± 31.4 (382-502), 443.4 ± 30.3 (386-504) μm, respectively. In control group, the mean scleral thickness in the superior, inferior, nasal and temporal quadrants were 381.3 ± 20.0 (341-436), 383.2 ± 16.0 (352-436), 389.2 ± 21.0 (353-440), 383.2 ± 19.2 (349-440) µm, respectively. The mean scleral thickness was significantly higher in all quadrants in FED group than in control group (p = 0.000).

CONCLUSION

In patients with FED, scleral thickness was significantly higher. FED is a progressive corneal disease that results in the accumulation of extracellular material in the cornea. These findings suggest that the accumulation of extracellular deposits may not be limited to the cornea. Due to their functional similarity and anatomical proximity, sclera may also be affected in FED.

Semiautomatic assessment of endothelial density and morphology in organ-cultured corneas - potential predictors for transplantation suitability and clinical outcome?

BACKGROUND

The quality of the endothelial cell layer is a major criterion for the approval of organ-cultured human donor-corneas for transplantation. We wanted to compare the predictive capacities of initial endothelial density and endothelium cell morphology for the approval of donor corneas for transplantation and for the clinical outcome after transplantation.

METHODS

The endothelial density and endothelium morphology in organ culture were examined by semiautomatic assessment of 1031 donor corneas. We performed a statistical analysis for correlations of donor-data and cultivation parameters regarding their predictive capacities for the final approval of donor corneas for transplantation and the clinical outcome of 202 transplanted patients.

RESULTS

Corneal endothelium cell density proved to be the only parameter with a certain predictive capacity with regard to the final decision, whether donor corneas are suitable for transplantation - however, the correlation was low (area under the curve [AUC] = 0.655). Endothelial cell morphology lacked any predictive power (AUC = 0.597). The clinical outcome regarding visual acuity seemed to be largely independent from both corneal endothelial cell density and morphology. Sub-analyses on transplanted patients stratified for their diagnoses vindicated these findings.

CONCLUSIONS

Higher endothelial density (above a cut-off level of 2000 cells/mm2), as well as better endothelial morphology do not seem to be critical for transplant-corneal functionality in organ culture and up to 2 years after transplantation. Comparable long-term studies on graft survival are recommended to determine, whether the present endothelial density cut-off levels might be too stringent.

Ex vivo cultivated retinal pigment epithelial cell transplantation for the treatment of rabbit corneal endothelial dysfunction

OBJECTIVE

Stem cell therapy is a promising strategy for the treatment of corneal endothelial dysfunction, and the need to find functional alternative seed cells of corneal endothelial cells (CECs) is urgent. Here, we determined the feasibility of using the retinal pigment epithelium (RPE) as an equivalent substitute for the treatment of corneal endothelial dysfunction.

METHODS

RPE cells and CECs in situ were obtained from healthy New Zealand male rabbits, and the similarities and differences between them were analyzed by electron microscopy, immunofluorescent staining, and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Rabbit primary RPE cells and CECs were isolated and cultivated ex vivo, and Na+/K+-ATPase activity and cellular permeability were detected at passage 2. The injection of cultivated rabbit primary RPE cells, CECs and human embryonic stem cell (hESC)-derived RPE cells was performed on rabbits with corneal endothelial dysfunction. Then, the therapeutic effects were evaluated by corneal transparency, central corneal thickness, enzyme linked immunosorbent assay (ELISA), qRT-PCR and immunofluorescent staining.

RESULTS

The rabbit RPE cells were similar in form to CECs in situ and ex vivo, showing a larger regular hexagonal shape and a lower cell density, with numerous tightly formed cell junctions and hemidesmosomes. Moreover, RPE cells presented a stronger barrier and ionic pumping capacity than CECs. When intracamerally injected into the rabbits, the transplanted primary RPE cells could dissolve corneal edema and decrease corneal thickness, with effects similar to those of CECs. In addition, the transplantation of hESC-derived RPE cells exhibited a similar therapeutic effect and restored corneal transparency and thickness within seven days. qRT-PCR results showed that the expressions of CEC markers, like CD200 and S100A4, increased, and the RPE markers OTX2, BEST1 and MITF significantly decreased in the transplanted RPE cells. Furthermore, we have demonstrated that rabbits transplanted with hESC-derived RPE cells maintained normal corneal thickness and exhibited slight pigmentation in the central cornea one month after surgery. Immunostaining results showed that the HuNu-positive transplanted cells survived and expressed ZO1, ATP1A1 and MITF.

CONCLUSION

RPE cells and CECs showed high structural and functional similarities in barrier and pump characteristics. Intracameral injection of primary RPE cells and hESC-derived RPE cells can effectively restore rabbit corneal clarity and thickness and maintain normal corneal function. This study is the first to report the effectiveness of RPE cells for corneal endothelial dysfunction, suggesting the feasibility of hESC-derived RPE cells as an equivalent substitute for CECs.

Assessment of corneal endothelial cell parameters using specular microscopy in previously infected SARS-CoV-2 patients

PURPOSE

To examine the long-term effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the corneal endothelium.

METHODS

This was a comparative, cross-sectional study that included subjects who had recovered from SARS-CoV-2 infection for at least 6 months (group 1) and a group of age- and sex-matched controls with no prior symptomatology or documentation of SARS-CoV-2 infection (group 2). After full ophthalmological evaluation, specular microscopy was used to examine the endothelial cell parameters, including endothelial cell density, coefficient of variation, hexagonality, average area, and central corneal thickness.

RESULTS

Sixty-four and 53 right eyes were included in groups 1 and 2, respectively. No statistically significant differences were detected in any of the examined specular parameters between the two groups.

CONCLUSION

SARS-CoV-2 infection may have no delayed sequel on the corneal endothelium. Future prospective studies with repeated examinations in the same subjects would be useful.

Corneal Endothelial Features in Patients Operated for Primary Congenital Glaucoma

PURPOSE

To compare the corneal endothelial cell morphology using specular microscopy imaging between primary congenital glaucoma (PCG) and age-matched healthy controls, and to determine if the endothelial cell parameters vary among different subtypes of PCG.

DESIGN

Retrospective case-control study.

PARTICIPANTS

One hundred forty-five eyes of 145 patients operated for PCG between 1991 and 2018 and who returned for a follow-up visit between June 2021 and May 2022. Three hundred and nineteen age-matched healthy individuals constituted the control group.

METHODS

Corneal endothelial cell layer analysis was performed with EM-3000 (Tomey) noncontact specular microscope. Patients were categorized according to the clinical subtypes of PCG (neonatal, infantile, and late-onset) based on the Childhood Glaucoma Research Network classification.

MAIN OUTCOME MEASURES

Specular microscopic parameters, including endothelial cell density (ECD), average cell size, coefficient of variation (CV), and maximum and minimum cell size, were compared with that of the control group.

RESULTS

Mean ± standard deviation (SD) age of patients at endothelial imaging was 13.5 ± 6.54 years, and there was a male preponderance (n = 88, 61%). The majority of the patients had infantile-onset PCG (n = 67, 46%). Eyes with PCG demonstrated a significantly lower ECD compared with controls (2158.7 ± 636.5 vs. 2840.9 ± 232.5 cells/mm2; P < 0.0001). Other endothelial cell parameters were also significantly worse in PCG compared with controls. The mean ± SD ECD was 2344.3 ± 544.3, 2131.9 ± 626.4, and 2054.2 ± 714.0 cells/mm2 in neonatal onset, infantile, and late-onset PCG groups, respectively. Although the ECD was lowest in the late-onset PCG group, there was no significant difference in the ECD between the 3 subgroups. Except for CV, all the endothelial cell parameters were significantly worse in eyes with Haab striae than in eyes without.

CONCLUSIONS

Patients with PCG have significantly lower ECD compared with healthy controls. Furthermore, other endothelial cell parameters were also significantly worse in the PCG group. These changes in the corneal endothelium in patients with PCG should be considered in long-term medical and surgical management.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Donor lamella thickness after ultrathin Descemet stripping automated endothelial keratoplasty and its relation to postoperative visual acuity and pre-operative lamella measures

BACKGROUND

To accurately measure ultrathin Descemet stripping automated endothelial keratoplasty (DSAEK) donor lamella thickness during the first postoperative year and to correlate this with pre-operative and other postoperative measurements.

METHODS

Donor lamella thickness in 41 eyes undergoing DSAEK for Fuchs endothelial dystrophy (FED) was measured using the Tomey Casia OCT directly after graft preparation and at 1 week and 1, 3, 6 and 12 months postoperatively. Visual acuity and endothelial cell density were measured as the secondary parameters.

RESULTS

Individual graft thickness profiles were shown to be fairly regular within the optically relevant area. There was a strong and highly significant correlation between the pre- and postoperative lamellar thicknesses at all time points (p < 0.0001). Compared with the measurements directly after preparation at the cornea bank, the lamella thickness decreased by 12% after 12 months. Between 1 and 12 months postoperatively, the lamella thickness (mean ± SD) changed from 112 ± 27 μm to 101 ± 21 μm. Best spectacle-corrected visual acuity (BSCVA) changed from 0.46 ± 0.30 logMAR pre-operatively through 0.36 ± 0.33 at 1 month to 0.13 ± 0.16 at 1 year postoperatively. The endothelial cell counts were comparable to those reported in previous studies.

CONCLUSIONS

Thickness profiles of individual grafts were fairly regular within the optically relevant area. A strong relationship between pre- and postoperative graft thicknesses was detected, and ultrathin DSAEK grafts prepared using methods similar to that applied in this study are expected to show a deswelling of around 12% during the first postoperative year. No correlation was detected between graft thickness and BSCVA.