Study of Correlation of Severity of Diabetic Retinopathy with Corneal Thickness and Endothelial Parameter Changes in...

Corneal endothelium plays an essential role in maintaining corneal transparency and hydration. Conditions or events causing endothelial cell loss beyond the threshold value can lead to loss of corneal transparency. Our study aimed to assess the effects of duration of Type 2 Diabetes Mellitus and diabetic retinopathy (DR) severity on the corneal endothelium using non-contact specular microscopy.

A prospective study was conducted on 200 eyes of diabetic patients and their age-matched controls. On their first visit, a detailed history including diabetic status, duration of diabetes, and previous eye surgeries was taken. A comprehensive ophthalmic evaluation was done. Corneal endothelial parameters like Central Corneal Thickness (CCT), Endothelial Cell Density (ECD), Coefficient of Variation (CV), and hexagonality were obtained using a non-contact Specular microscope. Data was tabulated and analysed using appropriate statistical tests, and a "p" value of less than 0.05 was considered statistically significant.

Endothelial cell hexagonality and duration of diabetes were found to be significantly correlated (p value of 0.001 using an independent t-test), indicating that a longer duration of diabetes causes morphological changes in the corneal endothelium. Other parameters, such as CCT, CV, and ECD, did not correlate significantly with HbA1c levels, diabetes duration, or DR severity.

In our study, we evaluated all endothelial parameters and correlated them with the duration of DM (<10 yrs and >10 yrs). Average ECD, CV, and HEX in the two subgroups were 2494.3 ± 405.2 cells/mm² and 2473.1 ± 321.1 cells/mm², 39.1 ± 4.8% and 37.8 ± 4.6%, and 45.6 ± 6.5% and 43 ± 6%, respectively. A significant positive correlation (p value of 0.00) was found between the duration of DM and HEX; however, no significant correlation was found between the duration of DM and ECD (p value of 0.774) and CV (p value of 0.154). Decreased HEX with increasing DM duration suggested that, over time, diabetes induces morphological changes that may eventually compromise endothelial health.

Our findings indicate that corneal endothelial cells undergo morphological changes with increasing duration of Diabetes. The findings of this study add to the literature on the effects of Diabetes on endothelial health, which might help improve the management of these patients. Future longitudinal studies with larger, diverse cohorts are recommended to validate these associations and explore therapeutic interventions to preserve corneal health in diabetes.