Corneal endothelial changes in type 2 diabetes mellitus relative to diabetic retinopathy

To evaluate the morphological features of corneal endothelial cells and their relationship with the stage of retinopathy in diabetes mellitus (DM).

Patients with type 2 DM and age-matched controls were included in this prospective, cross-sectional study. Patients with diabetic retinopathy (DR) were divided into no-DR, non-proliferative DR and proliferative DR based on the fundus findings. Endothelial measurements were obtained using specular microscopy (Topcon SP-3000P, Japan). Endothelial cell density, average cell area, co-efficient variation of cell area and percentage of hexagonal cells were evaluated. Central corneal thickness (CCT) was measured using an ultrasound pachymeter. Endothelial cell parameters and CCTs of DM and control groups were compared and subgroup analysis of the patients with DM was performed.

One hundred and twenty patients (mean age 59.5 ± 8.1 years) were in the DM group, 112 patients (mean age 57.3 ± 7.2 years) were in the control group. Both the endothelial cell density and the hexagonal cell rate were lower, while the CCT was higher in the DM group. There were no significant differences between these two groups in terms of average cell area and co-efficient variation of cell area. Significant differences were detected between endothelial cell density values of subgroups, and endothelial cell density decreased as the stage of the DR increased. The average cell area, co-efficient variation of cell area and CCT measurements were similar across subgroups. Hexagonality values were significantly different between subgroups, with the lowest ratio of hexagonal cells in the proliferative DR group.

Additional precautions should be taken to reduce the risk of endothelial decompensation prior to intraocular surgery, especially in patients with proliferative DR.