Corneal Endothelial Changes in Patients with Diabetes Mellitus: A Specular Microscopy Study

Purpose: To evaluate the changes in corneal endothelium in patients with diabetes mellitus using specular microscopy.

Setting: The study was performed in the outpatient clinic of Tanta ophthalmology Hospital.

Design: Cross-sectional study.

Patients and Methods: Corneal endothelium (CE) examination using noncontact specular microscopy that includes the following parameters: Coefficient of variation (CV), Endothelial cell density (ECD), Central corneal thickness (CCT), Hexagonality (HEX) and Cell size (Minimum, Maximum and Average).

Results: The study comprised 40 eyes of healthy individuals without diabetes, 40 eyes of patients with type II diabetes for less than 10 years, and 40 eyes of patients with type 2 diabetes for more than 10 years. This study showed no statistically significant differences in endothelial cell density (ECD) between diabetic patients and non-diabetics. In this study, we found a statistically significant increase in the mean Coefficient of variation (CV) from 34.73% in group A (non-diabetics) to 37.80% in group B (diabetics for less than 10 years) and increased to 40.63% in group C (diabetics for more than 10 years). According to the hexagonality (HEX%), our study showed a statistically significant decrease of mean HEX% from 54.70% in group A(non-diabetics) to 44.35% in group B (diabetics for less than 10 years) and decreased to 42.0% in group C (diabetics for more than 10 years). In our study, there was a statistically significant reduction in the mean central corneal thickness (CCT) from 518.18 µm in group A to 500.70 µm in group B and decreased to 491.93 µm in group C. The differences between groups A and B, and A and C were statistically significant. However, statistically non significant difference was noticed between groups B and C. Regarding the correlation between HBA1C and the specular microscopy parameters, our study showed that there was a significant negative correlation between HBA1C and HEX%, And between HBA1C and CCT. However, there was a positive relation between HBA1C and CV.

Conclusion: Diabetes mellitus (DM) has significant impacts on the CE. Compared to non-diabetic individuals, diabetic patients’ CE had a higher CV% and a lower HEX% and central corneal thickness. A strong negative correlation was found between HBA1C and HEX%, with a substantial positive correlation between HBA1C and CV%.