Influence of chronic hyperglycemia on corneal endothelium structural integrity with emphasis on hexagonality

Diabetes mellitus is a chronic metabolic disorder characterized by lasting hyperglycemia, which can poorly affect various ocular structures, including the corneal endothelium. The corneal endothelium plays a critical role in sustaining corneal transparency, and structural alterations such as reduced endothelial cell density and loss of hexagonal cell morphology may compromise its function. Endothelial cell hexagonality is a sensitive indicator of cellular pleomorphism and early endothelial stress.

To study the influence of chronic hyperglycemia on the structural integrity of the corneal endothelium, with special emphasis on endothelial cell hexagonality.

This observational, cross-sectional comparative study was conducted at a tertiary care centre from June 2024 to March 2025. A total of 200 participants were enrolled, comprising 100 patients with diabetes mellitus (Group A) and 100 age-matched non-diabetic controls (Group B). One eye (preferably the right eye) of each participant was evaluated using specular microscopy. Corneal endothelial parameters assessed included endothelial cell density (ECD), hexagonality percentage (HEX), coefficient of variation (CV) of cell area, and central corneal thickness (CCT). Glycaemic control was assessed using glycated haemoglobin (HbA1c) levels. Statistical analysis was performed using independent t-test, chi-square test, and Pearson correlation.

The diabetic group demonstrated significantly lower ECD (2577 ± 324.32 cells/mm2) and HEX (45.9 ± 7.37%) compared to non-diabetic controls (2714 ± 242.29 cells/mm2 and 52.14 ± 10.51%, respectively; p < 0.001). No significant difference was observed in CV and CCT between the groups. HEX showed a significant negative correlation with HbA1c levels (r = - 0.55, p < 0.001) and duration of diabetes (r = - 0.47, p = 0.002).

Chronic hyperglycemia is associated with significant deterioration of corneal endothelial structural integrity, particularly reflected by reduced HEX and ECD. These changes correlate with poor glycemic control and longer duration of diabetes, highlighting the need for regular corneal endothelial evaluation in diabetic patients.