Corneal Endothelial Alterations in Chronic Renal Failure

The effects of hemodialysis on the eye

The purpose of this study was to examine the effects of hemodialysis on the eye and its long-term consequences. Hemodialysis is a process that purifies the blood and maintains the balance of water, solutes, acid-base, and electrolytes. The eye, being primarily composed of fluid, has been speculated to be affected by this technique. To analyze these effects, a literature review was conducted, focusing on the anatomical structures, functions, and changes in the eye following hemodialysis. The search for relevant articles was carried out on PubMed, including studies published in English between 2000 and 2023. The results of the review showed that certain observations such as visual acuity, refraction, intraocular pressure, biometric parameters, and retinal nerve fiber layer did not show significant timing-related impacts, or there were conflicting findings. However, a connection was established between hemodialysis sessions and visual fields, parameters of visual-evoked potential, intraocular pressure in glaucoma, tear break-up time, Schirmer's test values, choroidal thickness, flow velocities of vessels, and ocular perfusion pressure values. In conclusion, it was determined that hemodialysis sessions can cause fluctuations that may complicate the assessment of eye health. To obtain a more accurate baseline evaluation, it is recommended to schedule ophthalmological examinations, a few hours after the hemodialysis session. Additionally, it is important to provide appropriate management for dry eyes and ocular hypertension, particularly during hemodialysis sessions. Coordination of these examinations with the timing of renal replacement therapy is advised to ensure optimal patient care.

The Relationship Between Serum Biochemical Variables and Corneal Biomechanics Measured by Corvis ST Among Healthy Young Adults

Purpose

To investigate the relationship between serum biochemical variables and corneal biomechanics in healthy young adults.

Methods

A total of 1645 healthy university students were included. Every student underwent an ophthalmologic examination by Corvis ST to measure the corneal biomechanics and a blood examination to evaluate the alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea, creatinine, and uric acid (UA) levels. Canonical correlation analysis (CCA) was conducted to assess their relationship.

Results

A significant relationship between serum biochemical variables and corneal biomechanics was found in both men and women. For men, the canonical correlation identified an association between the time of the first applanation (A1t), time of the second applanation (A2t), time of the highest concavity (HC-t), deflection amplitude of the highest concavity (HC-DeflA), and biomechanically corrected intraocular pressure (bIOP) with ALT, AST, urea, and UA (r = 0.235, P = 0.03). For women, a significant relationship between A1t, A2t, and bIOP with ALT and UA was found (r = 0.187, P < 0.01).

Conclusions

Elevated levels of ALT and UA were associated with softer corneas with greater elasticity and viscidity. The study provides novel evidence for the relationship between serum biochemical variables and ocular changes.

Translational Relevance

These findings may help clinicians perform adequate preoperative evaluations when performing corneal surgery on patients with liver or kidney disorders, as well as helping public health practitioners understand serum biochemical variables of corneal changes in healthy people.

The Impact of Severe COVID-19 on Corneal Endothelial Cells-Analysis of the In Vivo Noncontact Specular Microscopy

PURPOSE

This study aimed to investigate the effects of severe COVID-19 infection on the corneal endothelium via in vivo specular microscopy.

METHODS

This was an observational, prospective, and controlled study including 56 eyes of 56 severe COVID-19 patients, compared to after-recovery and 56 eyes of 56 age- and gender-matched healthy controls.

RESULTS

Endothelial cell density was lower in the active disease period compared to healthy controls (p = .001) and decreased even more after recovery (p < .0001). After recovery, the average cell area and coefficient of variation were higher compared to the active disease period (p < .0001 and p = .008, respectively) and the healthy controls (for both, p < .0001), whereas hexagonality was lower (p < .0001). Central corneal thickness increased in the active disease period compared to after recovery (p < .0001) and healthy controls (p = .002).

CONCLUSIONS

These results may be due to direct host-virus interaction or linked to immune dysregulation, subclinical corneal endotheliitis, or still yet a viral-mediated inflammation.

The effect of epilepsy and anti-epileptic drugs on the anterior and posterior segment of the eye

CLINICAL RELEVANCE

Understanding the causes of visual symptoms in epilepsy patients is important for early diagnosis and taking precautions.

BACKGROUND

The aim of this study is to evaluate the anterior and posterior segment parameters in patients with generalized tonic-clonic epilepsy (GTCE).

METHODS

This retrospective study included 50 eyes of 50 patients with GTCE and 55 eyes of 55 healthy controls. For all participants, detailed ophthalmic examinations were obtained from the files of patients. Anterior segment parameters were measured using corneal topography and non-contact specular microscopy, and posterior segment parameters were measured using swept-source optical coherence tomography.

RESULTS

The mean age of the patients with GTCE was 43.3 ± 13.2 years, and in the healthy controls it was 47.6 ± 10.7 years (p = 0.405). In GTCE patients, 34 patients were treated with monotherapy (MT) and 16 patients with polytherapy (PT). Central macular thickness (CMT) was statistically significantly thin in GTCE patients (p = 0.001). The average and four quadrants (superior, inferior, nasal, temporal) retinal nerve fibre layer (RNFL) were thinner in GTCE patients than in the healthy controls, but there was no statistically significant difference (p > 0.05, all). The central corneal thickness was statistically significantly thin in GTCE patients (p = 0.04). Endothelial cell density (ECD), endothelial cell number (ECN), and average cell area (ACA) were statistically significantly lower in GTCE patients than in the healthy controls (p < 0.05, all). Although the CMT, average, and four-quadrants RNFL were thinner in the PT group compared to the MT group, no statistically significant difference was observed (p > 0.05, all). Total high-order aberrations (HOAs) were 0.6 ± 0.4 in the MT group and 0.4 ± 0.1 in the PT group (p = 0.01). ECD, ECN, and ACA measurements were observed to be lower in the PT group compared to the MT group, but no statistically significant difference was detected (p > 0.05, all).

CONCLUSION

There could be statistically significant differences between GTCE patients and healthy controls in anterior and posterior segment parameters. This situation may be due to the epilepsy itself or to the antiepileptic drugs.

Correlations of Corneal Endothelial Morphology and Corneal Thickness With Anterior Segment Parameters in Healthy Individuals

PURPOSE

The purpose of this study was to investigate the associations between central corneal endothelial cell density (ECD), endothelial morphology, and corneal thickness (central corneal thickness) with the anterior chamber depth, corneal volume (CV), white-to-white (WTW) distance, mean anterior chamber angle (CAmean), and gender in healthy individuals.

METHODS

This observational study included 136 healthy volunteers. The ECD, coefficient of variation of cell area, and hexagonal cell appearance ratio (%Hex) were measured by means of specular microscopy. The central corneal thickness, anterior chamber depth, CV, WTW distance, and the angle width of 12 points were taken by the Pentacam HR Scheimpflug anterior segment imaging. The arithmetical mean of the 12 points was considered as the CAmean. We used mixed effect linear regression model for the statistical analysis of the data.

RESULTS

ECD was positively correlated with CV ( P = 0.028), while after adjusting for age, it was negatively correlated with age ( P < 0.001). Coefficient of variation of cell area was positively correlated with CAmean ( P = 0.036), while after adjusting for age, it was positively correlated with age ( P < 0.001) and CAmean ( P = 0.005). Hex was negatively correlated with WTW ( P = 0.023) and CAmean ( P = 0.025), and after adjusting for age, this correlation remained the same ( P = 0.029 when correlated with WTW and P = 0.035 with CAmean).

CONCLUSIONS

There were significant changes in the morphology of the corneal endothelial cells in eyes with wider anterior chamber angle. Greater pleomorphism and polymegethism of the corneal endothelium was observed in healthy patients with wider CAmean. Deepening of the anterior chamber as myopia progresses could render the corneal endothelium more fragile and susceptible to mechanical stress, which is an area worthy of further study.

Analysis of cardiovascular risk factors for the viability of cornea donors: a case-control study

OBJECTIVE

The main objective of the study was to evaluate the influence of arterial hypertension, diabetes, dyslipidaemia, smoking, alcoholism and COPD (chronic obstructive pulmonary disease) on the viability of the extracted tissue as well as the donor.

DESIGN

Observational case-control study.

SETTING

Regional hospital in Northern Spain.

PARTICIPANTS

1517 corneas were registered.

INTERVENTIONS

Patients' medical history was reviewed after corneal donation and evaluation. Previous medical information (age, sex and cardiovascular risk factors (CVRFs)) and data related to the donor (type of donor), the corneal tissue and its evaluation, and the viability of the implant were collected.

RESULTS

A total of 1517 corneas were registered and 81.5% of the donors presented at least one CVRF. In relation to the viability of the donor, it was observed that having suffered from COPD reduced the viability of the donor (no COPD: 93.8% vs COPD: 88%; OR=0.49; 95% CI: 0.28 to 0.84) while alcohol consumption increased it (drinker or ex-drinker: 95.8% vs non-drinker: 92.5%; OR=1.84; 95% CI: 1.01 to 3.33). Regarding tissue viability, decreased viability was observed in the presence of COPD (no COPD: 72.5% vs COPD: 64; OR=0.67; 95% CI: 0.47 to 0.96) and diabetes mellitus (no diabetes: 72.9% vs diabetes: 67.2%; OR=0.76; 95% CI: 0.58 to 0.99). As regards the viability of the implant, a total of 1039 corneas (68.9%) were suitable, observing decreased viability when suffering from COPD (no COPD: 69.8% vs COPD: 60.7%; OR=0.67; 95% CI: 0.47 to 0.94) and increased when having an active smoking habit (no habit: 65.3% vs habit: 74.1%; OR=1.52; 95% CI: 1.21 to 1.91).

CONCLUSIONS

Through this study, it can be concluded that in the absence of absolute exclusion criteria for donors, the assessment of how CVRF, alcoholism and COPD may affect the donor provides details about the quality of the tissue to be obtained.

An evaluation of corneal endothelial cell morphology in patients with thyroid-associated ophthalmopathy

INTRODUCTION

To evaluate corneal endothelial cell morphology in patients with thyroid-associated ophthalmopathy (TAO).

METHOD

Seventy-two eyes of 36 patients with TAO presenting to the ophthalmology department between January 2018 and January 2022 were included in the study. The findings were compared with 98 eyes of 49 healthy individuals. Mean endothelial cell density (ECD), coefficient of variation (CV), maximum cell area, minimum cell area, average cell area, and hexagonality ratio were obtained using non-contact specular microscopy. The thicknesses of peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) were measured using optical coherence tomography (OCT).

RESULTS

The TAO group consisted of 36 patients, 11 (30.6%) men and 25 (69.4%) women, and the control group of 49 healthy individuals, 14 (28.6%) men and 35 (71.4%). No significant differences were determined between the TAO and control groups in terms of the specular microscopy findings of mean ECD, CV, or hexagonality ratio values (p > 0,05). However, the mean Hertel values differed significantly between the two groups (p = 0.001). When the TAO group was divided into two subgroups based on patients who had previously received prednisolone therapy and those who had not, significant differences were observed in terms of mean ECD, CV, and hexagonality ratio values (p > 0.05).

CONCLUSION

Comparison of patients diagnosed with active TAO and receiving prednisolone therapy and the TAO patients with inactive disease revealed lower ECD, higher CV values, and lower hexagonality ratios in the prednisolone therapy group. These findings all suggest that inflammation in patients undergoing active disease affects the corneal endothelium.

TFOS Lifestyle: Impact of nutrition on the ocular surface

Nutrients, required by human bodies to perform life-sustaining functions, are obtained from the diet. They are broadly classified into macronutrients (carbohydrates, lipids, and proteins), micronutrients (vitamins and minerals) and water. All nutrients serve as a source of energy, provide structural support to the body and/or regulate the chemical processes of the body. Food and drinks also consist of non-nutrients that may be beneficial (e.g., antioxidants) or harmful (e.g., dyes or preservatives added to processed foods) to the body and the ocular surface. There is also a complex interplay between systemic disorders and an individual's nutritional status. Changes in the gut microbiome may lead to alterations at the ocular surface. Poor nutrition may exacerbate select systemic conditions. Similarly, certain systemic conditions may affect the uptake, processing and distribution of nutrients by the body. These disorders may lead to deficiencies in micro- and macro-nutrients that are important in maintaining ocular surface health. Medications used to treat these conditions may also cause ocular surface changes. The prevalence of nutrition-related chronic diseases is climbing worldwide. This report sought to review the evidence supporting the impact of nutrition on the ocular surface, either directly or as a consequence of the chronic diseases that result. To address a key question, a systematic review investigated the effects of intentional food restriction on ocular surface health; of the 25 included studies, most investigated Ramadan fasting (56%), followed by bariatric surgery (16%), anorexia nervosa (16%), but none were judged to be of high quality, with no randomized-controlled trials.

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.

Impact of Peripheral and Corneal Neuropathy on Markers of Ocular Surface Discomfort in Diabetic Chronic Kidney Disease

SIGNIFICANCE

There is a reduction in corneal nerve fiber density and length in type 2 diabetes mellitus with chronic kidney disease compared with type 2 diabetes mellitus alone; however, this difference does not result in worse ocular surface discomfort or dry eye disease.

PURPOSE

This study aimed to determine the clinical impact of corneal nerve loss on ocular surface discomfort and markers of ocular surface homeostasis in people with type 2 diabetes mellitus without chronic kidney disease (T2DM-no CKD) and those with type 2 diabetes mellitus with concurrent chronic kidney disease (T2DM-CKD).

METHODS

Participants were classified based on estimated glomerular filtration rates into two groups: T2DM-CKD (n = 27) and T2DM-no CKD (n = 28).

RESULTS

There was a significant difference between the T2DM-CKD and T2DM-no CKD groups in corneal nerve fiber density (14.9 ± 8.6 and 21.1 ± 7.1 no./mm 2 , respectively; P = .005) and corneal nerve fiber length (10.0 ± 4.6 and 12.3 ± 3.7 mm/mm 2 , respectively; P = .04). Fluorescein tear breakup time was significantly reduced in T2DM-CKD compared with T2DM-no CKD (8.1 ± 4.4 and 10.7 ± 3.8 seconds, respectively; P = .01), whereas ocular surface staining was not significantly different (3.5 ± 1.7 and 2.7 ± 2.3 scores, respectively; P = .12). In terms of ocular surface discomfort, there were no significant differences in the ocular discomfort score scores (12.5 ± 11.1 and 13.6 ± 12.1, respectively; P = .81) and Ocular Pain Assessment Survey scores (3.3 ± 5.4 and 4.3 ± 6.1, respectively; P = .37) between the T2DM-CKD and T2DM-no CKD.

CONCLUSIONS

The current study demonstrated that corneal nerve loss is greater in T2DM-CKD than in T2DM-no CKD. However, these changes do not impact ocular surface discomfort or markers of ocular surface homeostasis.

Corneal Endothelium: A Promising Quantitative Index for Graves Ophthalmopathy Activity Evaluation

PURPOSE

To investigate the corneal endothelium damage in Graves ophthalmopathy (GO) and its role as a promising quantitative index to evaluate GO activity.

DESIGN

Cross-sectional study.

METHODS

This study included 128 eyes of 64 patients with GO. All subjects underwent ophthalmologic examinations, including proptosis, tear break-up time (BUT), corneal fluorescein staining, and Schirmer test. Corneal endothelium was measured by noncontact specular microscope and ocular biometric parameters were measured by IOLMaster 700. Each eye was assigned a specific clinical activity score (CAS), then grouped as active (CAS ≥3 points) or inactive (CAS <3 points). Ocular parameters between the 2 groups were compared using generalized estimating equations accounting for inter-eye correlation, and receiver operating characteristic (ROC) curves were also obtained. Main outcome measures were parameters of corneal endothelium.

RESULTS

Among the included eyes, 81 eyes had inactive GO and 47 eyes had active GO. Corneal endothelial cell morphology was altered in active GO compared with inactive GO. The coefficient variation of cell area (CV) was significantly higher in active GO compared with inactive GO (37.0 [34.4-41.2]% vs 33.9 [30.9-36.8]%, P = .001), and positively correlated with CAS (r = 0.322, P < .001). Moreover, CV showed a diagnostic capacity to differentiate the active eyes from inactive eyes. The area under the ROC curve was 0.705.

CONCLUSIONS

Active GO had morphologic changes in corneal endothelium compared with inactive GO. CV is a sensitive indicator to reflect corneal endothelial function, and has the potential to be adopted as a noninvasive, objective, and quantitative index for evaluating the activity status of GO patients.

Tear dynamics testing and quantitative proteomics analysis in patients with chronic renal failure

Ocular surface changes may develop in patients with chronic renal failure (CRF) undergoing hemodialysis. In recent years, an association of CRF with dry eye syndrome has been emphasized. However, tear proteomics of CRF patients has not been analyzed. Here, we performed systematic profiling of the tear film proteins in CRF patients through use of isobaric tags for relative and absolute quantitative (iTRAQ) MS/MS, aiming to identify associations between dry eye symptoms and expression of tear proteomic changes in patients with CRF undergoing hemodialysis. Twenty CRF patients and ten healthy subjects underwent a series of ophthalmic examinations. Tear samples from the participants were analyzed by iTRAQ approach. A total of 1139 tear proteins were screened, and 212 differentially expressed proteins were identified. The pattern changes included 77 whose expression levels were upregulated (fold increase >1.2) whereas 135 others that were downregulated (fold decrease <1/1.2). Bioinformatics analysis showed that these proteins were significantly enriched in lipid metabolism, inflammatory, and immune response pathways. Furthermore, APOA1, APOA4, APOB, APOE, S100A8, S100A9, S100A4, HSP90B and other molecules were significantly changed. Our study elucidated the characteristics of tear dynamics and protein markers in CRF patients undergoing hemodialysis. Significance: Despite the association of chronic renal failure (CRF) with dry eye disease, there are no reports describing potentially important differentially expressed tear proteins in CRF patients undergoing hemodialysis. It is still a challenge to obtain a comprehensive description of the pathogenesis of dry eye in CRF patients which hinders establishing a patient specific therapeutic scheme. Our study is the first iTRAQ proteomics analysis of the tears of patients with CRF, which reveals the changes in the protein expression profile in CRF patients afflicted with dry eye disease. The identity was verified of some relevant differentially expressed proteins, and they may be candidate diagnostic markers of dry eye disease in patients with CRF. These tear film protein constituents found in hemodialysis patients can be of important clinical significance in treating this condition. SIGNIFICANCE: Despite the association of chronic renal failure (CRF) with dry eye disease, there are no reports describing potentially important differentially expressed tear proteins in CRF patients undergoing hemodialysis. It is still a challenge to obtain a comprehensive description of the pathogenesis of dry eye in CRF patients which hinders establishing a patient specific therapeutic scheme. Our study is the first iTRAQ proteomics analysis of the tears of patients with CRF, which reveals the changes in the protein expression profile in CRF patients afflicted with dry eye disease. The identity was verified of some relevant differentially expressed proteins, and they may be candidate diagnostic markers of dry eye disease in patients with CRF. These tear film protein constituents found in hemodialysis patients can be of important clinical significance in treating this condition.

Corneal Endothelial Morphology and Thickness Alterations in Patients With Severe Obstructive Sleep Apnea-Hypopnea Syndrome

PURPOSE

To investigate central endothelial cell density (ECD), morphology, and central corneal thickness (CCT) in patients newly diagnosed with severe obstructive sleep apnea-hypopnea syndrome (OSAHS) and to determine the correlation between these parameters and OSAHS severity.

METHODS

This prospective, comparative case series was conducted in a university ophthalmology clinic. In total, 51 patients recently diagnosed with severe OSAHS (apnea-hypopnea index above 30) and a paired, age and sex-matched control group of 44 healthy individuals were enrolled. After detailed ophthalmologic examination, specular microscopy measurement was performed for all participants. Central ECD, average cell area, coefficient of variation (CV) of cell area, hexagonal cell appearance ratio (% Hex), and CCT were compared between the groups. The Pearson correlation test was also used to assess the influence of the polysomnographic findings, that is, the proportion of each stage of sleep, apnea-hypopnea index, SpO2, mean and maximum duration of apneas, oxygen desaturation index, and arousal index on corneal endothelial morphometric parameters and CCT.

RESULTS

A total of 190 eyes were examined: 102 eyes of patients with severe OSAHS and 88 eyes of the control group. The mean ECD, CV, % Hex, and CCT values in the OSAHS group were 2439.25 ± 344.36 cells/mm, 41.41 ± 11.62, 45.22 ± 7.06%, and 533.88 ± 40.53 μm, respectively. ECD and CCT did not significantly differ between the groups (P = 0.46, P = 0.55, respectively). CV value was significantly higher (P = 0.009), whereas the %Hex was significantly lower (P = 0.01) in the OSAHS group. We observed a significant negative correlation between CCT and REM sleep percentage (P = 0.005).

CONCLUSIONS

Greater pleomorphism and polymegathism of corneal endothelium was found in patients with severe OSAHS when compared with healthy subjects. Low percentage of REM sleep, usually found in patients with OSAHS, may cause an increase in corneal thickness.

Corneal biomechanical properties in patients with kidney transplant

PURPOSE

The purpose of the study was to evaluate the corneal biomechanical properties in patients post kidney transplant and to compare them with healthy age-matched control.

MATERIALS AND METHODS

In this cross-sectional study, 68 patients with kidney transplant (study group) and 68 healthy individuals (control group) were analyzed with ocular response analyzer measurements. Only the right eye of each participant was assessed for corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOP_cc), and Goldmann-correlated intraocular pressure (IOP_g).

RESULTS

The mean CH in the study group was 9.70 ± 1.62 mmHg which was significantly lower than the control group with the mean CH of 10.60 ± 1.49 mmHg (P = 0.001). The mean IOP_cc was 18.17 ± 4.00 mmHg and 16.00 ± 3.94 mmHg in the study and control groups, respectively (P = 0.002). CRF and IOP_g were not significantly different between groups.

CONCLUSION

CH and IOP_ccare altered in kidney transplant patients.

Corneal endothelial cell density and microvascular changes of retina and optic disc in autosomal dominant polycystic kidney disease

Purpose:

Vascular endothelial dysfunction in autosomal dominant polycystic kidney disease (ADPKD) may affect the retinal vascular parameters due to structural similarities of kidney and retina. We aimed to evaluate the microvascular changes of retina and optic disc and also corneal endothelial cell density in patients with ADPKD.

Methods:

Forty-six eyes of 23 patients with ADPKD (Group 1), and 46 eyes of 23 sex- and age-matched healthy controls (Group 2) were included in this cross-sectional study. Demographic and ophthalmic findings of participants were collected. Corneal endothelial cell density (CECD) measurements were obtained by noncontact specular microscopy. Foveal retinal thickness, peripapillary retinal nerve fiber layer (RNFL) thickness, vessel density in different sections of the retina and optic nerve head were analyzed by optical coherence tomography angiography.

Results:

The mean ages were 41 ± 11 years for Group 1 and 39 ± 10 years for Group 2 (P = 0.313). CECD values were significantly lower in group 1 when compared to group 2 (2653 ± 306 cells/mm² and 2864 ± 244 cells/mm², respectively, P < 0.001). The foveal retinal thickness and RNFL thickness were similar, but superior quadrant thickness of RNFL was significantly lower in Group 1 than Group 2 (126 ± 14 μm vs. 135 ± 15 μm, P = 0.003). In Group 1, whole image of optic disc radial peripapillary capillary densities were significantly lower compared to Group 2 (49.4 ± 2.04%, and 50.0 ± 2.2%, respectively, P = 0.043). There was no significant difference regarding superficial, deep retinal vessel densities, foveal avascular zone and flow areas between the groups (P > 0.05 for all).

Conclusion:

Lower CECD values and decreased superior quadrant RNFL thickness, and microvascular densities of optic disc were revealed in patients with ADPKD. Evaluation of CECD and retinal microvasculature may be helpful in the management of these patients.

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.

Evaluation of changes in lens optical densitometry using Pentacam HR after renal transplantation: A prospective study

BACKGROUND

To compare the optical densitometric changes in the lens of patients with renal transplantation with those of a healthy group using Pentacam HR.

METHODS

Twenty-four right eyes of 24 healthy patients (Group 1) were compared with 24 right eyes of 24 kidney transplant recipients. Kidney transplant recipients were evaluated thrice (preoperatively: Group 2a, postoperative 1st month: Group 2b, postoperative 12th month: Group 2c). Corneal endothelial cell count, intraocular pressure, and central corneal thickness of all participants were measured. Lens optical densitometry was measured with Pentacam HR using 3D scanning mode. The optical density of the lens was analyzed by taking the corneal apex as the center and analysing the 12 mm diameter area. (Zone 1: 2.0 mm, Zone 2: 4.0 mm, and Zone 3: 6.0 mm).

RESULTS

Corneal endothelial cell count was 2571.2±106.7 cells/mm² in Group 1 and 2462.8±127.6 cells/mm² in Group 2a (p=0.001). For lens optical densities, significant differences were observed between the groups in Zone 1 and Zone 3, but the difference in Zone 2 was not significant (p=0.003, p=0.164, p=0.009, respectively). There was a positive correlation between dialysis time and preoperative lens optical densitometry in Zone 1, Zone 2, and Zone 3 (r= 0.496, r= 0.131, r= 0.463, respectively).

CONCLUSIONS

Although a decrease in lens transparency was observed after kidney transplantation, steroids may cause an increase in lens transparency in the postoperative period. Patients with renal transplantation should be followed closely for possible lens changes in the post-transplant period.

Evaluation of changes in corneal endothelium in chronic kidney disease

Purpose:

Chronic kidney disease (CKD) is an emerging health problem worldwide. In CKD corneal endothelial changes also occur probably due to accumulation of inflammatory cytokines and increased multiple toxic products. The aim of this study was to analyze the effect of CKD on corneal endothelium and correlate the findings with severity of disease with help of noninvasive technique.

Methods:

The study comprised 75 eyes of 75 cases divided into three groups with group A comprising of CKD cases on dialysis, group B of nondialysis CKD cases, and group C of controls. Each group had 25 cases each of either sex and between 15–80 age groups. All patients were investigated for blood urea, serum creatinine, and blood sugar and underwent complete ophthalmic examination of both eyes along with wide-field specular microscopy examination.

Results:

The majority of patients (33.3%) belonged to age range of 61–70 years with male predominance and the most common cause of CKD was found to be diabetes with 17 (34%) cases. We found normal corneal endothelial cell density (ECD) with the mean ECD of 2364.52 ± 397.72 mm² in the dialysis group, 2467.8 ± 352.88 mm² in nondialysis group, and 2521.68 ± 250.26 mm² in the control group of patients. However, we found significant increase in coefficient of variation (CV) with 36 ± 5.8% in dialysis group, 37 ± 4.5% in nondialysis group and 32 ± 0.8% in controls (P = 0.001) and decreased hexagonality (Hx) with 47 ± 7.3% in dialysis group, 46 ± 4.7% in nondialysis group and 51 ± 6.7% in the controls (P = 0.031). This showed increased tendency of pleomorphism and polymegathism in corneal endothelial cells in CKD cases. No correlation was found between blood urea or serum creatinine levels with endothelial parameters in any group.

Conclusion:

CKD causes morphological changes like polymegathism and pleomorphism in corneal endothelium and hence these cases are more vulnerable and special care should be taken before any intraocular surgical procedure.

Specular microscopy in clinical practice

Specular microscopy is a noninvasive diagnostic tool that allows for in vivo evaluation of corneal endothelium in health and various diseased states. Endothelial imaging helps in the diagnosis and management of several endothelial disorders. The review focuses on the principles of specular microscopy, limitations of endothelial imaging, and its interpretation in common conditions seen in the clinical practice. A thorough PubMed search was done using the keywords specular microscopy, corneal endothelium, and endothelial imaging.

Effect of 532 nm argon laser pan retinal photocoagulation on corneal thickness and corneal endothelial cell parameters among proliferative diabetic retinopathy patients

Background

Laser photocoagulation has been the mainstay treatment for diabetic retinopathy (DR). However, the applied laser light must pass through multiple ocular structures such as the cornea to reach the retina, potentially causing thermal injury to non-target tissues. The purpose of this study was to examine the effects of 532 nm Argon laser pan-retinal photocoagulation (PRP) on corneal thickness and corneal endothelial cell parameters by comparing central corneal thickness (CCT), endothelial cell density (ECD), and endothelial cell area coefficient of variation (CoV) before and after PRP for proliferative diabetic retinopathy (PDR). The effect of laser PRP on these corneal parameters may help in adapting treatment protocols to reduce corneal damage and thereby improve patient outcome.

Methods

This was a prospective cohort study involving newly diagnosed PDR patients. All patients underwent specular microscopy examination (CCT, ECD and endothelial cell area CoV) both pre-PRP and at 1-week and 6-weeks after the final PRP session (post-PRP). A Carl Zeiss Visulas Argon laser (532 nm) was used to perform PRP.

Results

A total of 33 newly diagnosed PDR patients were included in this study. There were no significant differences in mean CCT, ECD, and endothelial cell area CoV at 1-week and 6-weeks following PRP compared to pre-treatment baseline (p > 0.05). Further, there were no significant correlations between laser energy delivered and CCT, ECD and endothelial cell area CoV at either post-PRP examination time.

Conclusion

Argon laser (523 nm) energy delivered within recommended ranges for PRP had no adverse effects on corneal structure.

Systemic diseases and the cornea

There is a number of systemic diseases affecting the cornea. These include endocrine disorders (diabetes, Graves' disease, Addison's disease, hyperparathyroidism), infections with viruses (SARS-CoV-2, herpes simplex, varicella zoster, HTLV-1, Epstein-Barr virus) and bacteria (tuberculosis, syphilis and Pseudomonas aeruginosa), autoimmune and inflammatory diseases (rheumatoid arthritis, Sjögren's syndrome, lupus erythematosus, gout, atopic and vernal keratoconjunctivitis, multiple sclerosis, granulomatosis with polyangiitis, sarcoidosis, Cogan's syndrome, immunobullous diseases), corneal deposit disorders (Wilson's disease, cystinosis, Fabry disease, Meretoja's syndrome, mucopolysaccharidosis, hyperlipoproteinemia), and genetic disorders (aniridia, Ehlers-Danlos syndromes, Marfan syndrome). Corneal manifestations often provide an insight to underlying systemic diseases and can act as the first indicator of an undiagnosed systemic condition. Routine eye exams can bring attention to potentially life-threatening illnesses. In this review, we provide a fairly detailed overview of the pathologic changes in the cornea described in various systemic diseases and also discuss underlying molecular mechanisms, as well as current and emerging treatments.

Non-contact specular microscopy with Topcon instruments to assess central corneal thickness of healthy human eyes - A 20 year review

BACKGROUND

The purpose of this review was to evaluate the consistency of central corneal thickness (CCT) values reported with use of Topcon SP-2000 P and SP-3000 P non-contact specular microscopes since their introduction in 1999 with the two microscopes having been commonly used in a wide range of studies.

METHODS

As a primary resource, PubMed was used to search for peer-reviewed articles in any language that included CCT values obtained with non-contact specular microscopy reported for humans with nominally healthy corneas. Relevant articles were obtained and any cited publications also checked.

RESULTS

A total of 76 articles were identified which reported CCT on different small-to-moderate sized groups of individuals, published between 1999 and 2019. From these, an overall group mean CCT value of 0.525 ± 0.013 mm (median 0.525 mm) can be calculated. An estimated 95 % confidence interval (CI, based on 1.96 SD) would be between 0.500 and 0.550 mm. For the two Topcon models, the group mean ± SD values were 0.529 ± 0.013 mm and 0.517 ± 010 mm respectively. An assessment of the CCT data sets in relation to the reported average age indicated no statistically significant effect (p = 0.289, r = -0.129). Very similar average CCT values were also encountered in 4 other reports where these microscopes were used in large-scale population studies as well as in 2 other reports using the newer Topcon SP-1 P model.

CONCLUSIONS

The Topcon stand-alone non-contact specular microscopes have yielded consistent and predictable corneal thickness measures over many years.

Outcomes of corneal transplantation using donor corneas retrieved from patients with chronic kidney disease

Purpose:

To report the outcomes of corneal transplantation utilizing corneas retrieved from donors with chronic kidney disease (CKD).

Methods:

Outcomes of corneal transplantation (optical PK and EK) performed from Jan 2018 to Dec 2018 utilizing donor corneas retrieved from CKD patients was performed retrospectively.

Results:

Of the total of 233 donor corneas retrieved from CKD, 135 (57.9%) were utilized for transplantation after the routine screening protocol of the eye bank. Mean age of the donors was 56.2 ± 13.5 years. The mean endothelial cell density on specular microscopy of the donor corneas used for optical PK was 2685.7 ± 377.6 cells/mm² (range, 2028–3448 cells/mm²) and for EK was 2731.7 ± 189.1 cells/mm² (range, 2380–3194 cells/mm²). The overall primary graft failure rate was 5.1%. All grafts except 1, cleared in the PK group. In the EK group (6 DMEK and 16 DSAEK), 1 patient had a complete graft detachment and another 1 had a primary graft failure after DMEK.

Conclusion:

The donor corneas retrieved from chronic kidney disease patients are safe and suitable for optical keratoplasty provided they meet the criteria for transplantation.

Effect of microalbuminuria on corneal endothelium in patients with diabetes without retinopathy

BACKGROUND

The aim of this study was to investigate the effect of microalbuminuria on corneal endothelium in patients with diabetes without retinopathy.

METHODS

This cross-sectional study comprised 100 patients with type 2 diabetes mellitus (DM) without diabetic retinopathy and 92 control subjects without diabetes. Forty-five patients had microalbuminuria and 55 subjects were microalbuminuria negative. Endothelial measurements were obtained using specular microscopy. Endothelial cell density, average area, co-efficient of variation, maximum area, minimum area, hexagonality and corneal thickness were compared between the groups on the basis of microalbuminuria, DM duration and medication, HbA_1c , body mass index, serum lipid and protein profiles, hypertension and hyperlipidaemia diagnosis.

RESULTS

There were no significant differences in age, gender, endothelial cell density, average area, co-efficients of variation, maximum area, minimum area, hexagonality or corneal thickness among the microalbuminuria positive, microalbuminuria negative and control groups (p > 0.05). However, microalbuminuria positive patients had lower high-density lipoprotein levels than the microalbuminuria negative patients (p = 0.042). DM and control groups showed similar endothelial measurements (p > 0.05). Patients with a HbA_1c > 7 per cent (53 mmol/mol) had lower hexagonality value (p = 0.039) than in the subjects with a HbA_1c ≤ 7 per cent. No significant differences were found in endothelial parameters when groups were compared based on DM duration, medication and co-morbidities.

CONCLUSIONS

Microalbuminuria positive and negative patients with DM without retinopathy seem to have similar corneal endothelial measurements with controls. However, patients with a HbA_1c > 7 per cent should be monitored for deterioration in corneal endothelial cell morphology even without diabetic retinopathy, which might be critical prior to anterior segment surgery.

Substance P inhibits high urea-induced apoptosis through the AKT/GSK-3β pathway in human corneal epithelial cells

To investigate the effect of substance P (SP) on human corneal epithelial cells (HCECs) that have been stressed by a high urea environment and to determine the relationship between SP and the protein kinase B (AKT)/glycogen synthase kinase-3β (GSK-3β) signaling pathway. An in vitro model of chronic renal failure (CRF)-related dry eye was used to study HCECs that were treated with high urea concentrations. Cell proliferation was assayed using a cell counting kit-8 test. Besides, cell apoptosis was evaluated by flow cytometry. Furthermore, the effects of SP and the AKT inhibitor perifosine on the urea-treated HCECs were examined using immunofluorescence, quantitative real time polymerase chain reaction (qRT-PCR), and Western blot analysis. SP markedly reduced the number of apoptotic HCECs and decreased the cleaved caspase-3 expression levels while contributing to increased cellular proliferation (P < 0.05). The Western blot analysis and qRT-PCR experiments revealed that SP significantly increased the expression of p-AKT and p-GSK-3β (P < 0.05); additionally, these increases were attenuated after the perifosine inhibition of the AKT signaling pathway (P < 0.05). These in vitro experiments demonstrated that SP may protect against the apoptotic damage of HCECs caused by the high urea condition. The underlying mechanism may be related to the activation of the AKT/GSK-3β signaling pathway.

Reappraisal of the suitability of corneas from bacteremic donors for use in corneal transplants

Background

This study examined whether corneas from bacteremic donors could be used for corneal transplant.

Methods

Corneas donated to the National Eye Bank of Taiwan between 1 January 2014 and 30 June 2017 were included in this study. All the corneas had corneoscleral rim cultures during the retrieval process and were hypothermic preserved in the Optisol-GS storage medium. A microbial work-up flow chart was used for the sterility check of all grafts. Bacteremic donors were defined as those whose last blood culture before corneal donation was positive. The microbial contamination rates, the endothelial cell densities, the tissue utility rates and early complications after transplants were compared between the corneas from bacteremic versus non-bacteremic donors.

Results

697 corneas from 356 donors were analysed, 70 of which were from bacteremic donors. The microbial contamination rates of the corneas from bacteremic and non-bacteremic donors (7.1% vs 9.1%)(p=0.30) were close. None of the contaminated corneas grew the same bacterial strains as those from their blood cultures. The corneas from bacteremic donors and non-bacteremic donors have similar endothelial cell densities (2931±297 cells/mm2 vs 2903 ± 470 cells/mm2) (p=0.63). Corneas from bacteremic and non-bacteremic donors shared a similar utility rate (98.6% vs 99.4%)(p=0.41). None of the corneas caused infectious complications after transplants.

Conclusion

Our study showed that corneas from bacteremic and non-bacteremic donors have equally low contamination rates and are of the same quality in terms of endothelial cell density and safety.

Corneal endothelial changes in patients with vitamin D deficiency

Purpose:

The purpose of this study is to evaluate the effect of vitamin D deficiency on corneal endothelial layer using specular microscopy.

Methods:

Fifty-eight eyes of 58 patients whose vitamin D level was below 15 ng/ml and who had no ocular pathology were included in the study (Group 1). Forty eyes of 40 age-and sex-matched subjects were enrolled as control group (Group 2). Corneal endothelial cell density (CD), coefficient of variation (CV), hexagonal cell ratio (HEX), and central corneal thickness (CCT) were measured using specular microscopy (Konan Medical Inc., Nishinomiya, Japan). The obtained data were compared between the groups.

Results:

There was no significant difference between the groups in terms of age and gender (P = 0.344, P = 0.399, respectively). The mean CD value was 2772.79 ± 202.21 cells/mm² in Group 1 and 2954.97 ± 116.89 cells/mm² in Group 2 (P = 0.001). The mean CV value was 30.31 ± 3.65 in Group 1 and 28.20 ± 2.71 in Group 2 (P = 0.003). The mean HEX value was 46.56 ± 6.32 in Group 1 and 51.07 ± 5.28 in Group 2 (P = 0.001). The mean CCT value was 555.87 ± 36.90 μ in group 1 and 549.0 ± 37.39 μ in Group 2 (P = 0.96).

Conclusion:

Vitamin D deficiency may affect the corneal endothelial layer. Patients with vitamin D deficiency should be evaluated for endothelial parameters in particular before an intraocular surgery. Further studies are needed to confirm our results.

Resveratrol provides benefits in mice with type II diabetes-induced chronic renal failure through AMPK signaling pathway

Type II diabetes-induced ischemic injuries are known to lead to the rapid degeneration of the kidneys as a result of chronic renal failure. Chronic renal failure is a condition, which typically manifests with symptoms including cardiovascular system and left ventricular hypertrophy, atherosclerosis as well as arterial and aortic stiffness. Resveratrol is a multifunctional compound that has been reported to produce beneficial outcomes for patients with type-II diabetes due to prevention of oxidative stress and apoptosis. However, the beneficial effects of resveratrol in chronic renal failure and the underlying mechanisms have remained to be fully elucidated. The present study investigated the therapeutic effects of resveratrol in mice with chronic renal failure induced by type-II diabetes and assessed the mechanism of action. Oxidative stress, apoptosis and adenosine monophosphate-activated protein kinase (AMPK) in the renal cells of the model mice were assessed. Changes in inflammatory factors renal cells from experimental mice as well as insulin resistance were also analyzed. Morphological changes and immunocytes in renal cells were determined by immunostaining. The results demonstrated that resveratrol treatment decreased the apoptotic rate of renal cells from experimental mice. Oxidative stress also improved in renal cells, as indicated by inhibition of superoxide dismutase and reduced glutathione and 4-hydroxy-2-nonenal levels. In addition, insulin resistance was improved after an 8-week treatment with resveratrol. Inflammatory factors were decreased and factors promoting kidney function were increased after resveratrol treatment. Furthermore, morphological changes were observed to be ameliorated, indicating the therapeutic efficacy of resveratrol. In addition, immunocyte precipitation in renal cells was markedly decreased in resveratrol-treated mice. Importantly, the AMPK signaling pathway was found to be involved in the beneficial effect of resveratrol on the model mice. In conclusion, the present study suggested that resveratrol may be an ideal agent for the treatment of chronic renal failure induced by type-II diabetes through regulation of the AMPK signaling pathway, which should be further investigated in clinical trials.

The Effect of Chronic Pulmonary Disease and Mechanical Ventilation on Corneal Donor Endothelial Cell Density and Transplant Suitability

PURPOSE

To determine how chronic obstructive pulmonary disease (COPD) and mechanical ventilation time affect corneal donor endothelial cell density (ECD) and transplant suitability.

DESIGN

Retrospective cohort study.

METHODS

Setting: Institutional.

STUDY POPULATION

Total of 39 679 cornea donor eyes from SightLife Eye Bank between 2012 and 2016. Demographics, death-to-preservation time, ECD, lens status, medical history, time on mechanical ventilation, and suitability for transplantation were included.

MAIN OUTCOME MEASURES

ECD and transplant suitability.

RESULTS

Mean ECD was 2733 cells/mm². Mean age was 59 years. COPD affected 34.2% of donors. Mechanical ventilation was required in 35% of donors. Mean ventilation time was 1.3 days. After controlling for covariates, COPD was not found to be associated with poor transplant suitability (P = .22). Ventilation >7 days was associated with poor transplant suitability (P = .04). Donors with COPD and donors who were mechanically ventilated exhibited lower cell counts (P < .001, P < .01, respectively). Longer ventilation led to reduced endothelial cell density: ventilation time >7 days (-46.5 cells/mm², P < .001) and >30 days (-101.4 cells/mm², P = .02). Limitations of the study included the retrospective nature, dataset obtained from a single eye bank, and medical history documentation completed by eye bank technicians.

CONCLUSIONS

A high proportion of cornea donors have respiratory disease prior to donation. Ventilation time >7 days affected transplant suitability but the presence of COPD did not. Donors with COPD and donors who were mechanically ventilated had reduced cell counts. Longer ventilation times lead to increased cell loss. The presence of respiratory disease may affect tissue oxygenation and endothelial cell health.