Quantitative corneal anatomy: evaluation of the effect of diabetes duration on the endothelial cell density and corneal thickness.

Purpose: To evaluate the differences in endothelial cell density (ECD) and central corneal thickness (CCT) between type II diabetic patients and age-matched healthy controls, and determine the impact of time from diagnosis.

Methods: This is a comparative study of 77 eyes of type II diabetic patients (33 males, 44 females) and 80 eyes of healthy subjects (42 males, and 38 females) whose ages ranged from 38 to 56 years. CCT, ECD, HbA(1c) levels, and Goldmann tonometry were measured.

Results: The CCT was significantly higher and the ECD significantly lower in long-term diabetic patients (10 years + since diagnosis) when compared with short-term diabetic patients (<1 year since diagnosis) and controls (both p < 0.001). No significant differences in CCT (p = 0.30) and ECD (p = 0.31) were found between control groups. Multivariate analysis of variance indicated that there was a significant effect of the diabetes duration in CCT and ECD. In diabetic patients, a two-way analysis of variance showed that CCT was significantly different for a 7.5% HbA(1c) cut-off value, and ECD for both 7.0% and 7.5% HbA(1c) cut-off values.

Conclusion: Type II diabetes causes a significant alteration in corneal structure and function in the long term. Our study seems to confirm the effect of diabetes duration and poor glycaemic control on CCT and ECD changes.