Evaluation of Corneal Epithelial Thickness Across Different Stages of Diabetic Retinopathy Using Anterior Segment OCT

To compare the corneal epithelial thickness (CET), the density and number of central corneal subbasal nerve plexus (CSNP) between controls and different types of diabetic retinopathy in type 2 diabetics.

This cross-sectional study included participants who underwent a comprehensive evaluation comprising anterior segment optical coherence tomography, Keratograph 5M, fluorescein tear break-up time, and in vivo confocal corneal microscopy. Based on the Early Treatment Diabetic Retinopathy Study classification, patients with diabetes were categorized into no diabetic retinopathy (NDR) group, non-proliferative diabetic retinopathy (NPDR) group, and proliferative diabetic retinopathy (PDR) group.

A total of 75 eyes were examined- 20 eyes from 20 control subjects and 55 eyes from 55 patients with diabetes (20 NDR, 14 NPDR, 21 PDR). Compared to controls, diabetic eyes exhibited significant increases in corneal thickness (CT) in each region (all P < 0.05), as well as a decrease in CSNP density (15.18 ± 2.60 vs 11.77 ± 3.77, P = 0.040) and number (39.27 ± 6.87 vs 28.67 ± 9.71, P < 0.001). In the PDR group, CET in all areas (except at 6 mm) was significantly thinner (all P < 0.05). Univariate analysis indicated that central CET and CET measured 2 mm from the center were associated with age, CSNP density, and superior meibomian gland dropout. Multivariate analysis identified CSNP density as the only significant factor associated with CET (P < 0.05).

Diabetic eyes exhibit a reduction in CSNP density and number and an increase in CT. CET is significantly thinner in patients with PDR. Furthermore, CET correlates with CSNP density.