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.

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.

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.

Effect of elevated irrigation bottle height during cataract surgery on corneal endothelial cells in porcine eyes

BACKGROUND

Cataract surgery induces corneal endothelial cell loss (ECL). This study investigates the relationship between bottle height (BH) and ECL induced due to irrigation and aspiration (I/A) in cataract surgery and quantifies protective effects of intraoperatively used ophthalmic viscoelastic substances.

METHODS

Intermittent I/A without phacoemulsification was performed in porcine eyes for 10 min with varying BHs of 100 cm (BH100), 125 cm (BH125), 150 cm (BH150) or no treatment (control, no I/A). Additionally, in one group a dispersive ophthalmic viscoelastic substance was injected into the anterior eye chamber before treatment with I/A at a BH of 150 cm (BH150 + V). After exposure of the corneal endothelium to I/A, the corneas were prepared to split corneal buttons on day 0 and cultivated for 15 days. Endothelial cell density (ECD) was analyzed blinded on days 1, 8 and 15.

RESULTS

Relative ECL significantly correlated with irrigation BH (control (n = 13): -9.69 ± 6.03% (average ± standard deviation); BH100 (n = 12): -9.69 ± 4.81%-p = 1.000; BH125 (n = 14): -19.44 ± 7.30% - p < 0.001; BH150 (n = 13): -21.99 ± 6.70%-p < 0.001). I/A-induced ECL was significantly decreased by the injection of ophthalmic viscoelastic, as BH150 + V (n = 14; -10.92 ± 4.09%-p = 1.000) showed a cell loss comparable to the control group.

CONCLUSIONS

ECL is altered by I/A BH and reduced when viscoelastic substances are used.

Evaluation of corneal endothelium and correlation with disease severity in patients with Graves' ophthalmopathy: A specular microscopy-based study

PURPOSE

To investigate the possible corneal endothelial damage in Graves' ophthalmopathy (GO) and its relationship with GO activity.

METHODS

This cross-sectional study included 101 eyes of 55 patients with GO. Each eye was assigned a specific clinical activity score (CAS). Accordingly, they were classified as active (CAS ≥ 3) or inactive (CAS< 3). The corneal endothelium was measured using a non-contact specular microscope (Tomey EM-4000; Tomey Corp.). Endothelial cell density (ECD), average cell area (ACA), standard deviation of cell area (SD), coefficient of variation in cell area (CV), hexagonal cell ratio (HEX), and central corneal thickness (CCT) were recorded.

RESULTS

Among the eyes included in the study, 71 had inactive GO and 30 had active GO. ACA and HEX levels were lower (p<0,001) and CV values were higher (p<0.001) in patients with GO than in healthy subjects. Corneal endothelial cell morphology was altered in active GO compared to inactive GO. The SD (p=0,009) and CV (p<0,001) were significantly higher in active GO than in inactive GO. When the parameters examined were correlated with CAS, a statistically significant positive correlation was observed between proptosis (p=0,036, r=0,385) and CV (p=0,001, r=0,595).

CONCLUSION

Our study confirmed that morphological changes occur in the corneal endothelium of patients with GO. CV and SD values, in conjunction with CAS, can be used as non-invasive and quantitative indices to examine the activity status of GO. The demonstration of endothelial changes even in GO eyes with low CAS may be considered an incentive to include non-contact specular microscopy in the routine clinical evaluation of all patients with GO.

Comparison of endothelial cell loss in diabetic patients after conventional phacoemulsification and femtosecond laser-assisted cataract surgery

PURPOSE

This study aims to comparatively evaluate the morphological changes of the cornea after phacoemulsification (PHACO) and femtosecond laser-assisted cataract surgery (FLACS) without intercurrences in patients with type 2 diabetes mellitus.

METHODS

A total of 95 diabetic patients with moderate cataracts (N2 + and N3+), 47 undergoing PHACO and 48 undergoing FLACS, were selected randomly for the study. Surgeries were performed by a single surgeon between July 2021 and December 2021. Cumulative dissipated energy (CDE) and total balanced saline solution (BSS) data were obtained at the end of each surgery. Changes in corneal endothelial cell density (ECD) and central corneal thickness (CCT) at three months postoperatively were investigated.

RESULTS

After three months, evidence is lacking between groups in the CCT measures; the difference was neither statistically nor clinically relevant. However, for ECD, a significant and clinically significant difference was found; if all patients were treated with laser, the mean ECD would be 423.55 greater (RSE: 86.09; p-value < 0.001; 95% CI: 254.81-592.29) than the ECD potential means of 1656.423 among the conventional group (RSE: 74.90; p-value < 0.001; 95% CI: 1509.62-1803.23).

CONCLUSIONS

Diabetic patients under treatment with moderate cataracts may predispose themselves to a more significant loss of endothelial cells after conventional phacoemulsification than femtosecond laser-assisted cataract surgery.

TRIAL REGISTRATION

It was registered at The Brazilian Registry of Clinical Trials (ReBEC) with the code RBR-6d8whb5 (UTN code: U1111-1277-6020) on 17/05/2022.

SRT1720 attenuates UVA-induced corneal endothelial damage via inhibition of oxidative stress and cellular apoptosis

Corneal endothelium is mostly sensitive to oxidative pressure and mitochondrial dysfunction. However, the oxidative-antioxidant mechanism of corneal endothelial cells (CECs) remains partially defined. Silent information regulator 1 (SIRT1) is a well-studied therapeutic target of oxidative damage. This study aimed to determine the SIRT1 expression in ultraviolet A (UVA)-induced corneal endothelial damage and explore potential drugs to repair corneal endothelial oxidative injury. In this study, we showed that CECs exhibited cellular apoptosis, reactive oxygen species (ROS) accumulation and decreased SIRT1 expression. In addition, UVA induced the imbalance of mitochondrial homeostasis and function, involving in mitochondrial membrane potential, mitochondrial fusion/fission and mitochondrial energy metabolism. SRT1720, the SIRT1 activator, effectively increased SIRT1 expression and attenuated UVA-induced cell damage in CECs. The therapeutic effects of SRT1720 for corneal endothelial oxidative damage were also verified in UVA-irradiated mice model. Our findings indicated that SIRT1 maintained the oxidant-antioxidant balance in corneal endothelium, suggesting a new promising therapeutic target for corneal endothelial dysfunction.

The Multifarious Effects of Various Glaucoma Pharmacotherapy on Corneal Endothelium: A Narrative Review

Corneal endothelium is a single cell layer that is mainly responsible for maintaining corneal clarity. Endothelial damage secondary to toxicity, stress, or genetic predisposition are common and in conjunction with the low regenerative ability of the cells, making their preservation critical for maintaining visual acuity. Patients with glaucoma, who are estimated to be close to 80 million worldwide, have a plethora of reasons for developing endothelial damage, being exposed to a spectrum that extends from various medical and surgical interventions to the disease itself. The wide spectrum of glaucoma pharmacotherapy that has been recently extended by addition of newer classes of medications has been the focus of extensive research on its effects on corneal endothelium. Both basic and clinical research have attempted to shine a light on the complex mechanisms associated with the effects of glaucoma medication on corneal endothelium and to answer the important question as to whether these findings are clinically significant. The aim of this review is to summarize and present current literature of the various findings, both from in vivo and in vitro studies that have focused on the complex relationship between different classes of glaucoma medication and their effect on corneal endothelium.

Role of aquaporins in corneal healing post chemical injury

Aquaporins (AQPs) are transmembrane water channel proteins that regulate the movement of water through the plasma membrane in various tissues including cornea. The cornea is avascular and has specialized microcirculatory mechanisms for homeostasis. AQPs regulate corneal hydration and transparency for normal vision. Currently, there are 13 known isoforms of AQPs that can be subclassified as orthodox AQPs, aquaglyceroporins (AQGPs), or supraquaporins (SAQPs)/unorthodox AQPs. AQPs are implicated in keratocyte function, inflammation, edema, angiogenesis, microvessel proliferation, and the wound-healing process in the cornea. AQPs play an important role in wound healing by facilitating the movement of corneal stromal keratocytes by squeezing through tight stromal matrix and narrow extracellular spaces to the wound site. Deficiency of AQPs can cause reduced concentration of hepatocyte growth factor (HGF) leading to reduced epithelial proliferation, reduced/impaired keratocyte migration, reduced number of keratocytes in the injury site, delayed and abnormal wound healing process. Dysregulated AQPs cause dysfunction in osmolar homeostasis as well as wound healing mechanisms. The cornea is a transparent avascular tissue that constitutes the anterior aspect of the outer covering of the eye and aids in two-thirds of visual light refraction. Being the outermost layer of the eye, the cornea is prone to injury. Of the 13 AQP isoforms, AQP1 is expressed in the stromal keratocytes and endothelial cells, and AQP3 and AQP5 are expressed in epithelial cells in the human cornea. AQPs can facilitate wound healing through aid in cellular migration, proliferation, migration, extracellular matrix (ECM) remodeling and autophagy mechanism. Corneal wound healing post-chemical injury requires an integrative and coordinated activity of the epithelium, stromal keratocytes, endothelium, ECM, and a battery of cytokines and growth factors to restore corneal transparency. If the chemical injury is mild, the cornea will heal with normal clarity, but severe injuries can lead to partial and/or permanent loss of corneal functions. Currently, the role of AQPs in corneal wound healing is poorly understood in the context of chemical injury. This review discusses the current literature and the role of AQPs in corneal homeostasis, wound repair, and potential therapeutic target for acute and chronic corneal injuries.

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.

Temporary Myopic Shift in a Patient with Multiple Parallel-Line Endotheliitis

Here, we report the case of a patient with multiple parallel-line endotheliitis with myopic shift, which has not been previously reported. A 36-year-old man visited our clinic with blurred vision in his left eye. A slit lamp examination revealed an interesting pattern of multiple parallel lines of keratic precipitates, along with subtle corneal edema. The spherical equivalents measured in the right and left eyes were -9.25 and -11.875 diopter, respectively, with the left eye showing more myopic progression. On specular microscopy, endothelial cell loss was found in the left eye. After administration of a weak topical steroid, keratic precipitates and corneal edema resolved completely within 2 days. The myopic shift in his left eye recovered to -10.0 diopters. Multiple parallel-line endotheliitis can be easily treated with a weak topical steroid in a short period. A temporary myopic shift may occur, which in this case resolved upon disease recovery. However, corneal endothelial cell loss is inevitable; therefore, careful monitoring is needed.

Phakic iris-claw intraocular lens: calculations of power and long-term endothelial cells loss

A correction about phakic intraocular lens power calculation process, as it was stated by Li, Song & Song, is provided. It is explained that this calculation is based on the Van der Heijde formula and not on biometric formulas. A comment about the mechanisms of late endothelial cell loss following phakic intraocular lenses is done.

The soil and the seed: The relationship between Descemet's membrane and the corneal endothelium

Descemet's membrane (DM), the basement membrane of the corneal endothelium, is formed from the extracellular matrix (ECM) secreted by corneal endothelial cells. The ECM supports the growth and function of the corneal endothelial cells. Changes to DM are central to the diagnosis of the most common corneal endothelial disease, Fuchs endothelial corneal dystrophy (FECD). Changes in DM are also noted in systemic diseases such as diabetes mellitus. In FECD, the DM progressively accumulates guttae, "drop-like deposits" that disrupt the corneal endothelial cell monolayer. While the pathophysiologic changes to corneal endothelial cells in the course of FECD have been well described and reviewed, the changes to DM have received limited attention. The reciprocity of influence between the corneal endothelial cells and DM demands full attention to the latter in our search for novel treatment and preventive strategies. In this review, we discuss what is known about the formation and composition of DM and how it changes in FECD and other conditions. We review characteristics of guttae and the interplay between corneal endothelial cells and guttae, particularly as it might apply to future cell-based and genetic therapies for FECD.

Clinical comparison of manual and laser-cut corneal tunnel for intrastromal air injection in femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK)

PURPOSE

The most crucial step in deep anterior lamellar keratoplasty (DALK) is to achieve a bare Descemet's membrane. We aimed to assess a new femtosecond laser software that allows for a precise intrastromal tunnel creation for big bubble (BB) air injection using a real-time microscope-integrated optical coherence tomography.

MATERIALS AND METHODS

A retrospective review of 61 eyes of 61 patients with keratoconus. Before introducing the new software update, DALK was performed using a partial-assisted femtosecond laser (partial-thickness circular cut followed by a lamellar cut) with manual intrastromal tunnel creation (partial FS-DALK group). After the software update, the femtosecond laser created the intrastromal tunnel (full FS-DALK group).

RESULTS

In the full FS-DALK group, the BB's formation was significantly higher (64.3% vs. 36.4%, p = 0.04), and surgery time was shorter (21.8 ± 5.1 vs. 25.6 ± 6.8 min, p = 0.025) than in the partial FS-DALK. Penetrating keratoplasty conversion rate (7.1% vs. 15.1%, p = 0.432) was similar between the groups. Both groups showed statistically significant improvement in uncorrected and corrected distance visual acuity, central corneal thickness, surface asymmetry, and regularity indices. Endothelial cell density loss at 12 and 18 months was lower in the full compared with the partial FS-DALK group (12 months:10.0% vs. 16; 18 months: 10.7 vs. 16.5%, p < 0.001 for both comparisons).

CONCLUSIONS

Creating the intrastromal guiding tunnel using FS laser for air injection resulted in a higher rate of BB formation, reduced long-term endothelial cell loss, and operating room time.

iPSC-Derived Corneal Endothelial Cells

The corneal endothelium is the innermost monolayer of the cornea that maintains corneal transparency and thickness. However, adult human corneal endothelial cells (CECs) possess limited proliferative capacity, and injuries can only be repaired by migration and enlargement of resident cells. When corneal endothelial cell density is lower than the critical level (400-500 cells/mm2) due to disease or trauma, corneal endothelial dysfunction will occur and lead to corneal edema. Corneal transplantation remains the most effective clinical treatment therapy but is limited by the global shortage of healthy corneal donors. Recently, researchers have developed several alternative strategies for the treatment of corneal endothelial disease, including the transplantation of cultured human CECs and artificial corneal endothelial replacement. Early-stage results show that these strategies can effectively resolve corneal edema and restore corneal clarity and thickness, but the long-term efficacy and safety remain to be further validated. Induced pluripotent stem cells (iPSCs) represent an ideal cell source for the treatment and drug discovery of corneal endothelial diseases, which can avoid the ethical-related and immune-related problems of human embryonic stem cells (hESCs). At present, many approaches have been developed to induce the differentiation of corneal endothelial-like cells from human induced pluripotent stem cells (hiPSCs). Their safety and efficacy for the treatment of corneal endothelial dysfunction have been confirmed in rabbit and nonhuman primate animal models. Therefore, the iPSC-derived corneal endothelial cell model may provide a novel effective platform for basic and clinical research of disease modeling, drug screening, mechanistic investigation, and toxicology testing.

A systematic review on the effects of ROCK inhibitors on proliferation and/or differentiation in human somatic stem cells: A hypothesis that ROCK inhibitors support corneal endothelial healing via acting on the limbal stem cell niche

Rho kinase inhibitors (ROCKi) have attracted growing multidisciplinary interest, particularly in Ophthalmology where the question as to how they promote corneal endothelial healing remains unresolved. Concurrently, stem cell biology has rapidly progressed in unravelling drivers of stem cell (SC) proliferation and differentiation, where mechanical niche factors and the actin cytoskeleton are increasingly recognized as key players. There is mounting evidence from the study of the peripheral corneal endothelium that supports the likelihood of an internal limbal stem cell niche. The possibility that ROCKi stimulate the endothelial SC niche has not been addressed. Furthermore, there is currently a paucity of data that directly evaluates whether ROCKi promotes corneal endothelial healing by acting on this limbal SC niche located near the transition zone. Therefore, we performed a systematic review examining the effects ROCKi on the proliferation and differentiation of human somatic SC, to provide insight into its effects on various human SC populations. An appraisal of electronic searches of four databases identified 1 in vivo and 58 in vitro studies (36 evaluated proliferation while 53 examined differentiation). Types of SC studied included mesenchymal (n = 32), epithelial (n = 11), epidermal (n = 8), hematopoietic and other (n = 8). The ROCK 1/2 selective inhibitor Y-27632 was used in almost all studies (n = 58), while several studies evaluated ≥2 ROCKi (n = 4) including fasudil, H-1152, and KD025. ROCKi significantly influenced human somatic SC proliferation in 81% of studies (29/36) and SC differentiation in 94% of studies (50/53). The present systemic review highlights that ROCKi are influential in regulating human SC proliferation and differentiation, and provides evidence to support the hypothesis that ROCKi promotes corneal endothelial division and maintenance via acting on the inner limbal SC niche.

In vitro infection of human ocular tissues by SARS-CoV-2 lineage A isolates

BACKGROUND

The purpose of this study was: [1] to evaluate the infectivity of two SARS-CoV-2 lineage A variants on human ocular tissues in vitro, and [2] to evaluate the stability of SARS-CoV-2 lineage A variants in corneal preservation medium.

METHODS

Primary cultures of donor corneal, conjunctival, and limbal epithelium were inoculated with two lineage A, GISAID clade S isolates of SARS-CoV-2 (Hong Kong/VM20001061/2020, USA-WA1/2020), to evaluate the susceptibility of the ocular tissue to infection. Flat-mounted Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) grafts were inoculated with SARS-CoV-2 to evaluate the susceptibility of the endothelium to infection. All inoculated samples were immunostained for SARS-CoV-2 nucleocapsid (N)-protein expression to confirm positive infection. SARS-CoV-2 Hong Kong was then inoculated into cornea preservation media (Life4°C, Numedis, Inc.). Inoculated media was stored at 4^oC for 14 days and assayed over time for changes in infectious viral titers.

RESULTS

Corneal, conjunctival, and limbal epithelial cells all demonstrated susceptibility to infection by SARS-CoV-2 lineage A variants. Conjunctiva demonstrated the highest infection rate (78% of samples infected [14/18]); however, infection rates did not differ statistically between cell types and viral isolates. After inoculation, 40% (4/10) of DSAEK grafts had active infection in the endothelium. SARS-CoV-2 lineage A demonstrated < 1 log decline in viral titers out to 14 days in corneal preservation media.

CONCLUSIONS

SARS-CoV-2 lineage A variants can infect corneal, limbal, and conjunctival epithelium, as well as corneal endothelium. There was no statistical difference in infectivity between different lineage A variants. SARS-CoV-2 lineage A can survive and remain infectious in corneal preservation media out to 14 days in cold storage.

Hammered silver appearance of the corneal endothelium in Fuchs uveitis syndrome: A case report

BACKGROUND

Hammered silver appearance of the corneal endothelium is considered a characteristic change in iridocorneal-endothelial syndrome. Herein we report an interesting case of hammered silver appearance of the corneal endothelium in Fuchs uveitis syndrome (FUS).

CASE SUMMARY

A 49-year-old man with progressive vision loss in the right eye for one year was admitted to our hospital. The clinical manifestations of the patient’s right eye were mild conjunctival hyperemia, scattered stellate keratic precipitates on the corneal endothelium, normal depth anterior chamber, 2+ cellular reaction in the aqueous humor, diffuse iris depigmentation, absence of synechia, Koeppe nodules, opalescent lens, and vitreous opacity. FUS and a complicated cataract were diagnosed based on the typical clinical manifestations. The corneal endothelial changes were recorded in detail by slit-lamp examination, specular microscopy, and in vivo confocal microscopy before cataract extraction, revealing a hammered silver appearance of the corneal endothelium in the affected eye, a wide-band dark area, as well as irregular corneal endothelial protuberances and dark bodies of various sizes. Subsequently, the patient underwent phacoemulsification combined with intraocular lens implantation, and his postoperative visual acuity recovered to 1.0.

CONCLUSION

Hammered silver appearance of the corneal endothelium in FUS, which is considered a more serious manifestation of endothelial damage, is rare and may be caused by many irregular protrusions in the corneal endothelium.

Long-term Effects of Uncomplicated Traumatic Hyphema on Corneal and Lenticular Clarity

PURPOSE

To evaluate the long-term effects of uncomplicated traumatic hyphema on endothelial morphology, anterior segment structure, and corneal and lenticular densitometry.

METHODS

In this retrospective comparative study, eyes with a history of uncomplicated traumatic hyphema were compared with the healthy contralateral unaffected eyes. The corneal endothelial cell properties were captured using specular microscopy. Anterior segment analysis, corneal densitometry (12-mm corneal diameter), and lens densitometry measurements were performed using the Pentacam imaging system.

RESULTS

Measurements were obtained at a mean follow-up of 49.5 ± 15.8 months after injury. The average endothelial cell density was significantly lower in the study group than in the control group (2,506.6 ± 294.0 cells/mm² vs. 2,665.7 ± 195.0 cells/mm², p = 0.020). There was no difference between the groups in respect of polymegathism and pleomorphism (p = 0.061 and p = 0.558, respectively). All the investigated corneal tomographic and angle parameters were similar in both groups (all p > 0.05). The corneal densitometry values in all concentric zones and layers showed no statistically significant difference between the groups (p > 0.05 for all). The lens zone 1 densitometry value was significantly higher in the study group than in the control group (9.6% ± 1.1% vs. 8.9% ± 1.2%, p = 0.031). No difference was observed in zone 2 and 3 (p = 0.170 and p = 0.322, respectively). The degree of hyphema was not correlated with endothelial cell and lenticular clarity loss (p = 0.087 and p = 0.294, respectively).

CONCLUSIONS

Even if traumatic hyphema is not complicated, long-term outcomes indicate endothelial cell loss and increased lenticular density.

Evidence that Nectin-3 is the soybean agglutinin binding protein on rat corneal endothelium cell surfaces

The means by which the lectin soybean agglutinin (SBA) binds to the corneal endothelium cell surface following explantation into organ culture was investigated using Sprague-Dawley rats. SBA binding does not occur in freshly isolated and fixed rat corneal endothelium. However, after 48 h in organ culture, SBA binding occurs in a punctate pattern that clearly outlines all endothelial cells of the tissue monolayer. To determine what cell surface component was responsible for this binding, a series of experiments were employed that focused on the possibility that SBA bound to a nectin molecule(s). To this extent we performed a series of immunocytochemical localizations using antibodies against either nectin-2, nectin-3 or nectin-4. Of these, only nectin-3 bound to the endothelium in a manner that mimicked SBA binding. To further verify that nectin-3 bound SBA, displacement experiments employing non-labeled SBA were undertaken. Following a 48 h organ culture, tissues were fixed and incubated with SBA followed by exposure to nectin-3 antibody. No subsequent immunofluorescence could be detected, indicating that anti-nectin-3 binding was prevented. Likewise, when organ-cultured tissues were fixed and incubated in anti-nectin-3 antibody, followed by SBA exposure, no SBA binding could be detected. These results suggest that stresses accompanying explantation of the tissue into organ culture promote the appearance of nectin-3 around the cell periphery. The emergence of nectin-3 along the peripheral endothelial cell membrane in organ culture may imply a necessary role for this molecule in maintaining monolayer integrity and barrier function during either a pathologic condition, wound repair, or in organ storage.

Temperature effects on the disappearance and reappearance of corneal-endothelium primary cilia

INTRODUCTION

To elucidate the specific functions of the primary cilia in corneal endothelial cells (CECs) by investigating the histological changes of corneal endothelium exposed at low temperature.

STUDY DESIGN

Experimental study.

METHODS

This study involved corneas freshly obtained from Japanese white rabbits preserved in Optisol™-GS (Bausch & Lomb) corneal storage medium at 4 °C for 0, 1, and 7 days. Corneas preserved for 7 days were also incubated at 37 °C in culture media for an additional 2 days. A rabbit CEC line was also preserved in Optisol™-GS at 4 °C for 0 and 1 day. The corneal endothelium specimens and CECs were then assessed by immunostaining and scanning electron-microscopy (SEM).

RESULTS

Immediately post isolation, the CECs of the specimens showed positive immunostaining for primary cilia (i.e., approximately 20%) via anti-acetylated alpha Tubulin antibody and SEM observation. Primary cilia were found to have attenuated/disappeared on the corneal endothelium specimens preserved for 1 or 7 days at 4 °C. After an additional 2-day incubation at 37 °C, primary cilia reappeared on the corneal endothelium specimens (approximately 20%). The disappearance of cilia during the preservation period was also observed in the immortalized CECs.

CONCLUSION

The findings in this study using rabbit corneas indicate that the primary cilia of corneal endothelium preserved at low temperature disappeared, then reappeared after returning to body temperature, suggesting that temperature has a direct effect on the primary cilia of corneal endothelium.

[CyPass microstent trimming with special cutting forceps : Video article]

OBJECTIVE OF SURGERY

A CyPass®-microstent (Alcon, Fort Worth, TX, USA) extending too far into the anterior chamber should be trimmed as close as possible to the scleral spur to avoid progression of endothelial cell reduction.

INDICATIONS

After CyPass implantation, if there is a significant loss of corneal endothelial cells due to the Cypass microstent extending too far into the anterior chamber, trimming or removal of the CyPass stent is necessary.

CONTRAINDICATIONS

There are no contraindications.

SURGICAL TECHNIQUE

As shown in our video, which is available online, a special cutter (19 Gauge Ahmed Micro Stent Cutter, MicroSurgical Technology Inc, Redmond, WA, USA) is inserted into the anterior chamber via a 1.5-mm wide corneal paracentesis made directly opposite to the CyPass stent. It is then possible to trim the anterior part of the stent. The severed fragment is removed using the head of the forceps. Finally, the previously inserted viscoelastic agent can be aspirated and the paracentesis can be hydrated.

POSTOPERATIVE TREATMENT

After the surgery vision testing as well as control of intraocular pressure and location of the stent are carried out. Antibiotic eye drops and ointment are postoperatively applied.

EVIDENCE

There is still no standardized protocol for the procedure to trim the CyPass stent. Performing the trimming in our clinic using the procedure described here has so far not led to any complications. Long-term data about the development of the endothelial cell measurement after CyPass trimming are not yet available.

Evaluation of corneal, ocular surface, and meibomian gland changes in obstructive sleep apnea syndrome

PURPOSE

To evaluate the ocular surface, eyelid changes, meibomian gland morphology, corneal endothelial morphology, and corneal topographic measurements in patients with obstructive sleep apnea syndrome (OSAS).

METHODS

There were 47 patients diagnosed with OSAS and 47 healthy volunteers included in the study. Non-invasive tear break-up time (NITBUT), corneal topography, meibography, and specular microscopy were performed.

RESULTS

The mean ages of the study and control groups were 45.77±9.65 years and 44.26±8.54 years, respectively (P=0.229). The presence of floppy eye lid (17% vs. 0%; P=0.006) and lid margin abnormality score (1.09±0.8 vs. 0.21±0.51; P<0.001) were significantly different between the study and the control groups. There were insignificant differences between the groups in NITBUT and corneal topographic measurements, except for the ACT (556.96±42.4μm vs. 569±103μm, P=0.037). The mean endothelial cell density (CD) in the OSAS and control groups were 2609±259.96 and 2756±179 cells/mm², respectively (P=0.002). Meibomian gland loss in the lower and upper eyelids was significantly higher in the OSAS group (P<0.001 for both).

CONCLUSION

OSAS patients develop eyelid margin abnormalities, loss of meibomian glands, and morphological changes in the meibomian glands. A significant reduction in corneal endothelial CD indicates that systemic hypoxia in OSAS has an effect on the cornea.

Hyperglycemia induces corneal endothelial dysfunction through attenuating mitophagy

Hyperglycemia increases the risk of corneal endothelial dysfunction, resulting in damage to corneal endothelial structure and function. However, the effect and mechanism of hyperglycemia-induced corneal endothelial damage remain elusive. In this study, we demonstrated that hyperglycemia reduced the expression of pump-related protein Na⁺/K⁺ ATPase and barrier-related protein ZO-1. Moreover, we found hyperglycemia caused abnormal changes of morphological mitochondria and dynamics in vitro. In addition, the decreased levels of mitophagy were further confirmed Western blotting and LC3B-Mitotracker Immunofluorescence. Exogenous application of mitophagy agonist carbonyl cyanide m-chlorophenyl hydrazine (CCCP) increases the expression of Na⁺/K⁺ ATPase and ZO-1 in corneal endothelial cells through up-regulated mitophagy in vitro. In addition, CCCP effectively reverses the phenomenon of corneal opacity and increased corneal thickness in diabetic mice. Therefore, our demonstrated the novel function of mitophagy in the pathogenesis of diabetic cornea endothelial dysfunction, and provide potential approach for treating diabetic corneal endothelial dysfunction.

A Prospective Evaluation of the Effect of Mitomycin-C on Corneal Endothelium after Photorefractive Keratectomy for Myopia Correction

PURPOSE:

The aim of the study was to assess the effect of mitomycin-C (MMC) 0.02% application on corneal endothelium in patients undergoing photorefractive keratectomy (PRK) for the correction of myopia and compound myopic astigmatism.

METHODS:

A prospective observational study including patients with myopia who underwent PRK plus intraoperative application of MMC 0.02%. All patients underwent noncontact specular microscopy preoperatively and 6 months postoperatively. The following parameters were analyzed: mean cell area (MCA), central corneal endothelial cell density (ECD), and coefficient of variation (CV) in cell size.

RESULTS:

One hundred and thirty-nine eyes of 73 patients with a mean age of 24.95 ± 3.23 years were included in the study. Mean baseline preoperative pachymetry was 519.54 ± 28.62 μm. The mean preoperative spherical equivalent was −4.6 ± 2.3D (range from −1D to −10D) which decreased to mean postoperative spherical equivalent of −0.125 ± 0.32D. Mean baseline ECD was 2829.3 ± 188.8 cells/mm², MCA was 354.6 ± 24.9 μm²/cell, CV was 0.35 ± 0.06, and hexagonality was 50.1 ± 6.64. The mean ECD decreased by 43 ± 1.6 cells/mm² which was not statistically significant (P = 0.07). The MCA increased by 5 ± 1.3 μm²/cell, but this was not statistically significant (P = 0.07). However, both the CV and percentage of hexagonal cells showed statistically significant differences in the median values as compared to preoperatively (P < 0.001).

CONCLUSION:

In our study, MMC had no significant effect on corneal endothelial cell counts or MCA. While there were statistically reduced CV and percentage of hexagonal cells, these did not appear to be clinically significant. MMC is safe to use routinely to prevent haze formation in PRK.

Demographic profile and clinical course of Fuchs endothelial corneal dystrophy in Mexican patients

PURPOSE

To describe the demographic characteristics and clinical course of Fuchs endothelial corneal dystrophy (FECD) in a Mexican-mestizo population.

METHODS

A retrospective observational and longitudinal study was performed in consecutive patients with the clinical diagnosis of Fuchs endothelial corneal dystrophy seen at our institution. Initial and last follow-up best-corrected visual acuity, slit-lamp findings, and specular microscopy endothelial morphometric parameters were analyzed.

RESULTS

One hundred and two eyes belonging to 51 patients were included in the analysis. Median age at the time of diagnosis was 69 years (range, 25-87 years) with a female-to-male ratio of 3.3:1. Visual loss (40%) followed by glare (13.3%) and fluctuating matutine vision loss (13.3%) was the most common complaints at presentation. Regarding FECD staging, 65 (63.7%) were classified as stage-I FECD, 21 (20.6%) stage-II, and 15 (14.7%) as stage-III. A high percentage of eyes (44.1%) presented visual impairment ( ≤ 20/50) at presentation, and the presence of isolated corneal guttata was the most common stage of presentation (64%) at slit-lamp examination. While fifty-nine (57.8%) eyes did not require any medical or surgical management, 17 (16.7%) eyes were managed with hypertonic saline eyedrops alone or in combination with bandage contact lens, and 18 (17.6%) required corneal transplantation. Penetrating keratoplasty alone (8 eyes, 44.4%), or in combination with cataract extraction and intraocular lens implantation (3 eyes, 16.7%), was the most frequent surgical technique performed.

CONCLUSION

Demographical characteristics of Fuchs dystrophy regarding age at presentation, gender distribution, and clinical stage at the time of diagnosis did not differ significantly from other international reports. Almost 20% of these patients will require keratoplasty during the disease, emphasizing the need for safer and more reproducible keratoplasty techniques.

Descemet's membrane injury and regeneration, and posterior corneal fibrosis, in rabbits

The purpose of this investigation was to study Descemet's membrane and corneal endothelial regeneration, myofibroblast generation and disappearance, and TGF beta-1 localization after Descemet's membrane-endothelial excision (Descemetorhexis) in rabbits. Thirty-six rabbits had 8 mm Descemetorhexis and standardized slit lamp photos at 1, 2 and 4 days, 1, 2 and 4 weeks, and 2, 4 and 6 months, as well as multiplex IHC for stromal cell markers keratocan, vimentin, and alpha-smooth muscle actin (SMA); basement membrane (BM) components perlecan, nidogen-1, laminin alpha-5, and collagen type IV; and corneal endothelial marker Na,K-ATPase β1, and TGF beta-1, with ImageJ quantitation. Stromal transparency increased from the periphery beginning at two months after injury and progressed into the central cornea by six months. At six months, central transparency was primarily limited by persistent mid-stromal neovascularization. Stromal myofibroblast zone thickness in the posterior stroma peaked at one month after injury, and then progressively decreased until to six months when few myofibroblasts remained. The regeneration of a laminin alpha-5 and nidogen-1 Descemet's membrane "railroad track" structure was accompanied by corneal endothelial closure and stromal cell production of BM components in corneas from four to six months after injury. TGF beta-1 deposition at the posterior corneal surface from the aqueous humor peaked at one day after Descemetorhexis and diminished even before regeneration of the endothelium and Descemet's membrane. This decrease was associated with collagen type IV protein production by corneal fibroblasts, and possibly myofibroblasts, in the posterior stroma. Descemet's membrane and the corneal endothelium regenerated in the rabbit cornea by six months after eight mm Descemetorhexis. Real-time quantitative RT-PCR experiments in vitro with marker-verified rabbit corneal cells found that 5 ng/ml or 10 ng/ml TGF beta-1 upregulated col4a1 or col4a2 mRNA expression after 6 h or 12 h of exposure in corneal fibroblasts, but not in myofibroblasts. Stromal cells produced large amounts of collagen type IV that likely decreased TGF beta-1 penetration into the stroma and facilitated the resolution of myofibroblast-generated fibrosis.

[Prospective Study on Corneal Safety Evaluation of Children/Adolescents with Low and Moderate Myopia after Long-Term Orthokeratology]

OBJECTIVE

To observe the possible changes in the integrity of the cornea and corneal endothelial cells of children/adolescents with low or moderate myopia after long-term wearing of orthokeratology (ortho-k) lenses, as well as the time when the relevant changes occur, so as to evaluate the safety of long-term wearing of ortho-k lens and to provide a reference for the safety evaluation of subjects wearing ortho-k lenses.

METHODS

Subjects were recruited in the Contact Lens Clinic, West China Hospital, Sichuan University for a three-year prospective study. Ortho-k of the same brand was matched for the subjects. The central corneal thickness (CCT), corneal endothelial cell density (ECD), and hexagonal cell ratio (HEX) were measured prior to the wearing of ortho-k lenses and after wearing ortho-k lenses for 1 month, 3 months, 6 months, and every 3 months until 36 months. The results of corneal fluorescence staining were recorded during each follow-up. When corneal staining was observed, the Efron grading standard was used for grading and corresponding treatment was given.

RESULTS

A total of 33 (66 eyes) myopic patients were included in the study. 15 cases (46.2%) reported having binocular foreign body sensations and tearing within the first week of wearing the lenses. After the subjects became adapted to wearing the lenses, the symptoms disappeared without intervention. During the follow-up period, 31 cases (93.94%) of binocular corneal staining were observed, of which, 24 cases (72.73%) were graded as G0, receiving no treatment, 5 cases (15.15%) were graded as GⅠ, and 2 cases (6.06%) were graded as GⅡ. Corresponding clinical treatment for corneal staining was given to the GⅠ and GⅡ subjects. This study found that the corneal ECD was inversely proportional to age ( r=－0.380, P=0.002). During the three-year follow-up period, the subjects' left eye ECD decreased from the baseline at 24 months and the right eye ECD decreased from the baseline at 27 months ( P<0.05). The CCT results in the subjects showed that CCT became thinner at 1 month after wearing the lens ( P<0.05), but the follow-up CCT showed a stable trend.

CONCLUSION

After three years of long-term follow-up, no serious corneal complications occurred in children/adolescents with moderate and low myopia after long-term wearing of ortho-k lens. The corneal ECD of both eyes started decreasing 24 months after wearing the ortho-k lenses and the CCT decreased 1 month after wearing the lenses.

Ex vivo expansion and characterization of human corneal endothelium for transplantation: a review

The corneal endothelium plays a key role in maintaining corneal transparency. Its dysfunction is currently treated with penetrating or lamellar keratoplasty. Advanced cell therapy methods seek to address the persistent global deficiency of donor corneas by enabling the renewal of the endothelial monolayer with tissue-engineered grafts. This review provides an overview of recently published literature on the preparation of endothelial grafts for transplantation derived from cadaveric corneas that have developed over the last decade (2010–2021). Factors such as the most suitable donor parameters, culture substrates and media, endothelial graft storage conditions, and transplantation methods are discussed. Despite efforts to utilize alternative cellular sources, such as induced pluripotent cells, cadaveric corneas appear to be the best source of cells for graft preparation to date. However, native endothelial cells have a limited natural proliferative capacity, and they often undergo rapid phenotype changes in ex vivo culture. This is the main reason why no culture protocol for a clinical-grade endothelial graft prepared from cadaveric corneas has been standardized so far. Currently, the most established ex vivo culture protocol involves the peel-and-digest method of cell isolation and cell culture by the dual media method, including the repeated alternation of high and low mitogenic conditions. Culture media are enriched by additional substances, such as signaling pathway (Rho-associated protein kinase, TGF-β, etc.) inhibitors, to stimulate proliferation and inhibit unwanted morphological changes, particularly the endothelial-to-mesenchymal transition. To date, this promising approach has led to the development of endothelial grafts for the first in-human clinical trial in Japan. In addition to the lack of a standard culture protocol, endothelial-specific markers are still missing to confirm the endothelial phenotype in a graft ready for clinical use. Because the corneal endothelium appears to comprise phenotypically heterogeneous populations of cells, the genomic and proteomic expression of recently proposed endothelial-specific markers, such as Cadherin-2, CD166, or SLC4A11, must be confirmed by additional studies. The preparation of endothelial grafts is still challenging today, but advances in tissue engineering and surgery over the past decade hold promise for the successful treatment of endothelial dysfunctions in more patients worldwide.

RNA-seq identifies long non-coding RNAs as potential therapeutic targets for human corneal endothelial dysfunction under oxidative stress

Human corneal endothelial cells (CECs) have limited ability to regenerate in vivo. Oxidative stress has been proposed as one potential reason. Understanding the mechanism of oxidative stress-induced CEC dysfunction might provide novel targets for improving CEC regenerative capacity, and help develop non-surgical therapeutic strategies for CEC dysfunction. Long non-coding RNAs (lncRNAs) are non-coding transcripts with multiple biological functions. The roles of lncRNAs in ocular cells under oxidative stress have been widely studied, such as lens epithelial cells, trabecular meshwork cells, and retinal ganglion cells. In the current study, we established oxidative stress-induced CEC dysfunction model in vitro. By RNA sequencing technology, we identified 824 differentially expressed lncRNAs in CEC dysfunction group, including 667 upregulated lncRNAs and 157 downregulated lncRNAs. We finally demonstrated that CEC functions under oxidative stress, including cellular proliferation, apoptosis, and anti-oxidative stress ability, could be regulated by different lncRNAs, including lncRNA-Z93241.1, lncRNA-XLOC_000818, and lncRNA-AC007952.4. Targeting these lncRNAs might be useful to further elucidate the pathology of CEC dysfunction and develop novel therapeutic strategy.

Poly(ADP-ribose) polymerase inhibitor PJ34 protects against UVA-induced oxidative damage in corneal endothelium

Fuchs endothelial corneal dystrophy (FECD) is one of the main causes for corneal endothelial blindness, which is characterized by the progressive decline of corneal endothelial cells. Poly (ADP-ribose) polymerase (PARP) was reported to be involved in cell death and apoptosis of several diseases. However, the role of PARP1 in the progression of FECD remains elusive. In the present study, we reported that UVA irradiation caused the corneal endothelial damage and corneal edema in mice, which was accompanied with the elevated activity of PARP1 and PAR. The PARP1 inhibitor PJ34 resolved the corneal edema and protected corneal endothelium from UVA-induced oxidative damage, mitochondrial dysfunction, and cell apoptosis. Mechanistically, PARP1 inhibition exerted its anti-apoptotic effects through downregulation of the phosphorylation levels of JNK1/2 and p38 MAPK and subsequently the increase of MKP-1. Our results suggest that PARP1 inhibition protects corneal endothelium from UVA-induced oxidative damage, which provides a potential alternative strategy for the therapy of FECD.

Animal models of corneal endothelial dysfunction to facilitate development of novel therapies

Progressive corneal endothelial disease eventually leads to corneal edema and vision loss due to the limited regenerative capacity of the corneal endothelium in vivo and is a major indication for corneal transplantation. Despite the relatively high success rate of corneal transplantation, there remains a pressing global clinical need to identify improved therapeutic strategies to address this debilitating condition. To evaluate the safety and efficacy of novel therapeutics, there is a growing demand for pre-clinical animal models of corneal endothelial dysfunction. In this review, experimentally induced, spontaneously occurring and genetically modified animal models of corneal endothelial dysfunction are described to assist researchers in making informed decisions regarding the selection of the most appropriate animal models to meet their research goals.

Analysis of corneal densitometry and endothelial morphometry in patients with psoriasis

BACKGROUND

To evaluate corneal endothelial properties and corneal densitometry values in patients with psoriasis and to compare the results with those of healthy controls.

METHODS

This prospective, comparative, and cross-sectional study included 106 eyes of 53 patients who were diagnosed with psoriasis and 106 eyes of 53 age-gender matched healthy controls. All patients were evaluated in terms of ocular surface tests such as Schirmer-1 and tear break-up time (TBUT). Corneal endothelial measurements were performed using noncontact specular microscopy. Corneal tomographic and densitometric measurements were obtained using the Scheimpflug imaging system. Measurements were also evaluated according to the psoriasis area and severity index (PASI) score.

RESULTS

The mean TBUT and Schirmer 1 test values were significantly lower in the psoriasis group than in the healthy controls (p = 0.02, p < 0.001, respectively). While the mean endothelial cell density was significantly lower in patients with psoriasis than the healthy controls (2389.9±314.9 cells/mm² vs. 2512.4±289.7 cells/mm², p = 0.02), the mean average endothelial cell area, standard deviation of cell area, coefficient of variation of cell area were significantly higher in patients with psoriasis (426.6±62.7 µm² vs. 403.2±46.1 µm², p = 0.01; 206.4±52.3 µm² vs. 183.2±43.8 µm², p = 0.006; and 48.1±6.3% vs. 45.7±6.7%, p = 0.04, respectively). Most of the densitometry measurements in concentric zones were higher in patients with psoriasis than in healthy controls, but none of the differences reached statistical significance.

CONCLUSIONS

A regular eye examination is crucial in patients with psoriasis because corneal structural and functional changes, particularly endothelial alterations, are of utmost importance in planning intraocular surgeries in patients with psoriasis.

Comparison of the rabbit and human corneal endothelial proteomes regarding proliferative capacity

The shortage of human donor corneas has raised important concerns about engineering of corneal endothelial cells (CECs) for clinical use. However, due to the limited proliferative capacity of human CECs, driving them into proliferation and regeneration may be difficult. Unlike human CECs, rabbit CECs have a marked proliferative capacity. To clarify the potential reason for this difference, we analysed the proteomes of four human corneal endothelium samples and four rabbit corneal endothelium samples with quantitative label-free proteomics and downstream analysis. We discovered that vitamin and selenocompound metabolism and some signaling pathways such as NF-kappa B signaling pathway differed between the samples. Moreover, TGFβ, PITX2 and keratocan were distinctively expressed in rabbit samples, which might be associated with active proliferation in rabbit CECs. This study illustrates the proteomic differences between human and rabbit CECs and might promote CEC engineering strategies.

Differential gene expression analysis of corneal endothelium indicates involvement of phagocytic activity in Fuchs' endothelial corneal dystrophy

Fuchs' endothelial corneal dystrophy (FECD) is a progressive vision impairing disease caused by thickening of Descemet's membrane and gradual degeneration and loss of corneal endothelial cells. The aim of this study was to identify differentially expressed genes between FECD-affected and unaffected corneal endothelium to gain insight into the pathophysiological mechanisms underlying this disease. Microarray gene expression analysis was performed on total RNA from FECD-affected and unaffected corneal endothelium-Descemet's membrane (CE-DM) specimens using the Illumina HumanHT-12 v4.0 expression array. RNA from pools of FECD-affected (n = 3 per pool) and individual unaffected (n = 3) specimens was used for comparison. Altered expression of a sub-set of differentially expressed genes was validated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in independent specimens. Bioinformatics analysis was performed using InnateDB to reveal functional relationships among the differentially expressed genes and molecular pathways involved in the disease. A total of 16,513 genes were found expressed in the corneal endothelium of which 142 genes were differentially expressed between FECD-affected and unaffected endothelium (log₂ fold-change ≥1.5, corrected p-value ≤0.05). Most of the genes were up-regulated (126) and a small proportion down-regulated (16) in affected corneal endothelium. Of the twelve genes prioritised for validation, differential expression of 10 genes, including those ranked 57th and 81st by significance validated by qRT-PCR (8 up-regulated and 2 downregulated, corrected p ≤ 0.05), one gene showed a trend for up-regulation in affected endothelium, consistent with the microarray analysis and another was up-regulated in an independent study indicating robustness of the differential expression dataset. Bioinformatic analysis revealed significant over-representation of differentially expressed genes in extracellular matrix reorganisation, cellular remodelling, immune response, and inflammation. Network analysis showed functional inter-relatedness of the majority of the dysregulated genes and revealed known direct functional relationships between 20 of the genes; many of these genes have roles in macrophage differentiation, phagocytosis and inflammation. This is the second report of microarray gene expression analysis in FECD. This study revealed a set of highly dysregulated genes in the corneal endothelium in FECD. More than a third of the dysregulated genes in the disease have been discovered for the first time and thus are novel. The dysregulated genes strongly suggest the presence of phagocytic cells, most likely immune cells, and inflammation in corneal endothelium in the disease. This study provides a molecular framework for delineating the mechanisms underlying these cellular processes in FECD.

The impact of biomechanics on corneal endothelium tissue engineering

The integrity of innermost layer of the cornea, the corneal endothelium, is key to sustaining corneal transparency. Therefore, disease or injury causing loss or damage to the corneal endothelial cell population may threaten vision. Transplantation of corneal tissue is the standard treatment used to replace malfunctioning corneal endothelial cells. However, this surgery is dependent upon donor tissue, which is limited in supply. Hence, tissue engineers have attempted to construct alternative transplantable tissues or cell therapies to alleviate this problem. Nevertheless, the intrinsic non-dividing nature of corneal endothelial cells continues to foil scientists in their attempts to yield large numbers of cells in the laboratory for use in such novel therapies. Interestingly, the contribution of the biomechanical properties of the underlying extracellular matrix (ECM) on cell division, tissue development and maintenance has been extensively investigated in other many cell types. However, the impact of biomechanics on corneal endothelial cell behaviour is relatively unexplored. Here, we describe contemporary tissue engineering solutions aimed at circumventing donor tissue scarcity. We review the ECM structure and biomechanical features of corneal endothelial cells. We discuss the alterations of ECM in endothelial disease development and progression and point out the role of ECM in developing a tissue-engineered corneal endothelium. We highlight the main biomechanical cues, including topographical and mechanical features, that impact cellular behaviors. Finally, we discuss the influence of biomechanical cues on cell and tissue development, and how corneal endothelial cells response to individual biomechanical stimuli in tissue engineering, which have implications for designing an engineered endothelium and maintaining cell function.

Corneal endothelial morphology and central corneal thickness in type 2 diabetes mellitus patients

Purpose

This study aimed to examine the corneal endothelial morphology and thickness in patients with Type 2 diabetes mellitus (T2DM) and compare them with age and sex-matched nondiabetic controls.

Methods

This hospital-based cross-sectional observational study was conducted in the ophthalmology department of a tertiary hospital consisting of 262 patients (131 with T2DM as cases and 131 without diabetes who served as controls). All patients underwent a comprehensive ocular examination including visual acuity, slit-lamp biomicroscopy, intraocular pressure measurement. Central corneal thickness (CCT), endothelial cell density (ECD), coefficient of variance (CV), and percentage of hexagonal cells (HEX) were compared between the cases and controls. Predictors of corneal endothelial dysfunctions were analyzed. Data analysis was done by Statistical Package for the Social Sciences (SPSS) version 17.0. Chi-square test, Fisher's exact test, and Spearman's rho correlation analysis were used as appropriate.

Results

Patients with T2DM showed poorer visual acuity and higher intraocular pressure. As compared to controls, patients with T2DM had thicker CCT, lesser ECD, decreased HEX, and higher CV but the differences were statistically nonsignificant. HbA1c levels showed a significant positive correlation with CCT and CV and a negative correlation with ECD. Macroalbuminuria and higher albumin creatinine ratio was associated with an increase in CV in patients with T2DM.

Conclusion

Our study showed that poorly controlled patients with T2DM and those with macroalbuminuria have corneal endothelial abnormalities.

[Specular microscopy findings in active uveitis]

PURPOSE

To study the effect of ocular inflammation in active uveitis on the corneal endothelium.

MATERIALS AND METHODS

This is a prospective cross-sectional study involving 63 eyes of 38 patients with active newly-diagnosed uveitis. Eighty-four eyes of 42 non-uveitic subjects served as a control group. All patients underwent detailed ophthalmic examination, laser flare photometry, and non-contact specular microscopy. Eyes with uveitis had a follow-up visit at one month after initiation of treatment, including laser flare photometry and specular microscopy.

RESULTS

The mean age of the active uveitis patients was 33 (range: 9-67 years) with 21 men (55%) and 17 women (45%). For the uveitis patients at baseline, the mean flare value was 32ph/ms (range: 15-100ph/ms) with flare photometry value ≥50ph/ms in 13 eyes (21%) and<50ph/ms in 50 eyes (79%). At baseline, cell density (CD) of the uveitis patients was similar to CD in control eyes (p꞊0.16). The percent of hexagonality was significantly lower (p<0.0001), and the coefficient of variance (CV) (p<0.0001) and central corneal thickness (CCT) (p<0.0001) were significantly higher than in the control group. After one month, there was a significant decrease in flare photometry values (p<0.0001), with a mean flare value of 14.5ph/ms (range: 4-60ph/ms). In the active uveitis group, the overall results of specular microscopy did not significantly vary between the initial examination and the 1-month examination. For eyes with flare photometry value ≥50ph/ms at baseline, CD and hexagonal cell count significantly increased on the 1-month examination (p꞊0.01 and p꞊0.02 respectively), while CV and CCT decreased significantly at the one-month follow-up visit (p꞊0.007/p꞊0.03 respectively). For eyes with flare photometry value at baseline <50ph/ms, there was no significant differences in specular microscopy results between the initial examination and the 1-month examination.

CONCLUSIONS

In eyes with newly-diagnosed uveitis and active anterior chamber inflammation, specular microscopy shows transient qualitative abnormalities of the corneal endothelium that depend on the severity of the anterior chamber inflammation as measured by the laser flare meter.

Examination of the effects of COVID 19 on corneal endothelium

PURPOSE

To demonstrate the effects of the disease on the corneal endothelium in individuals recovering from COVID-19 through specular microscopy.

METHODS

Eighty individuals recovering from COVID-19 (group 1) and 72 healthy controls (group 2) were included in this prospective study. After examining visual acuity, refractive defect detection, anterior and posterior segment examinations, and specular microscopy measurements were calculated from images with at least 100 cells. The mean cell density (CD), mean coefficient of variation (CV), mean hexagonal cell percentage, mean cell area (AVG), and central corneal thickness (CCT) were evaluated.

RESULTS

The mean time from diagnosis of the disease in group 1 was 54.25 ± 6.36 days. The mean time elapsed since the PCR test became negative was 38.45 ± 6.87 days. Only four were treated in the hospital. Specular microscopy data showed that the CD was 2713.56 ± 246.25 and 2845.80 ± 299.27 in groups 1 and 2, respectively (p = 0.003). The CV values were 42.92 ± 6.79 and 40.16 ± 5.97, respectively (p = 0.009). The hexagonality were 46.51 ± 7.35 and 49.12 ± 6.87, respectively (p = 0.024). The AVG was 371.60 ± 34.64 and 353.16 ± 35.29, respectively (p = 0.007). The CCT values were 553.00 ± 73.2, and 526.84 ± 33.57, respectively (p = 0.005).

CONCLUSION

A decrease in the number of endothelial cells and hexagonal cells (polymorphism) as well as an increase in the cell area change coefficient (polymegatism) and the average cell area were observed from corneal specular microscopic examination of individuals recovering from COVID-19 in the early period of the disease. These results may be important in understanding the systemic effects of the disease.

Corneal endothelial cells and central corneal thickness in patients with neurofibromatosis type 1

Purpose:

The aim of this study was to evaluate the morphological properties of corneal endothelial cells and central corneal thickness (CCT) in patients with neurofibromatosis type 1 (NF1) and to compare them with age-matched healthy controls.

Methods:

Nineteen NF1 patients and 38 healthy individuals were recruited. All participants underwent complete ophthalmological examination as well as noncontact specular microscopy to measure endothelial cell density (ECD), average cell area (AVG), coefficient of variation of cell area (CV), the percentage of hexagonal cells, and CCT. Eyes with previous ocular trauma, inflammation or surgery, and preexisting corneal and ocular surface diseases were excluded.

Results:

NF1 patients had higher ECD compared to healthy controls of the same age (2764.2 ± 270.4 versus 2570.4 ± 449.2 cells/mm, respectively), although at a borderline level (P = 0.051). Patients with NF1 presented significantly lower CV and AVG when compared to controls (32.9 ± 4.6 versus 37.8 ± 9.5%, P = 0.011 and 364.9 ± 34.4 versus 406.0 ± 107.4 µm, P = 0.038, respectively). The NF1 group had significantly higher hexagonality in comparison with controls (55.7 ± 6.5 versus 50.5 ± 9.9%, P = 0.025). CCT was similar between the two groups (P = 0.955).

Conclusion:

Our results show that corneal endothelium has more favorable morphological characteristics in NF1 patients compared to healthy individuals of the same age.