Corneal Endothelial Changes in Patients of Type 2 Diabetes Mellitus Using Specular Microscopy

Objectives: To compare corneal endothelial cell changes namely, endothelial cell density (ECD), percentage polymegathism (CV) and pleomorphism (6A) along with central corneal thickness (CCT) in patients of type 2 diabetes mellitus with normal age and sexmatched subjects. To correlate corneal endothelial changes with diabetic retinopathy status, total duration of disease and glycemic control (HbA1c) levels. Study Design: A case-control study in a tertiary care hospital of south India. Population: 270 eyes of patients of type 2 diabetes mellitus and 270 eyes of age and sex matched controls were included in the study. Method: Demographic data such as age, gender and relevant diabetic history was obtained. A detailed evaluation of both cases and controls including complete anterior segment evaluation and posterior segment evaluation was done to grade the retinopathy. Noncontact specular microscopy was used to study the corneal endothelium. Results: The mean endothelial cell density (ECD) was found to be significantly lower in patients with type 2 diabetes mellitus as compared to controls (p value = 0.0086) No statistically significant difference was observed in the coefficient of variation of cell size (CV), hexagonality (6A). Apparently normal, minimal increase was seen in central corneal thickness (CCT) between cases and controls. Though the endothelial cell density decreased with increase in severity of retinopathy, this was not found to be statistically significant. Conclusion: Patients of type 2 diabetes mellitus have a lower endothelial cell count and higher rate of endothelial cell loss when compared to normal controls. The endothelial changes appear similar to changes caused due to aging process suggesting accelerated aging in diabetic cornea. The changes in corneal endothelium are proposed to be a part of the endothelium syndrome seen in patients of diabetes mellitus.