Association of severity of diabetic retinopathy with corneal endothelial and thickness changes in patients with diabetes mellitus.

Abstract

To analyse the central corneal thickness, endothelial cell density and morphology in patients with diabetes mellitus (DM). We analysed corneal endothelium, i.e. central corneal thickness (CCT), endothelial cell density (ECD), coefficient of variation in cell size (CV), and hexagonality (Hex) with specular microscopy in patients with type 2 DM and compared with age-matched controls. The influence of diabetic retinopathy (DR) severity, duration of DM, and level of glycosylated haemoglobin (HbA1c) was also analysed. The study cohort included 592 eyes of 592 diabetic patients and 596 eyes of 596 control subjects. A significant difference was found in CCT (522.1 ± 36.6 μm in DM, 514.9 ± 37.1 μm in controls; P = 0.001), ECD (2484.5 ± 299.5 cells/mm2 in DM, 2555.9 ± 258.2 cells/mm2 in controls; P = 0.017), CV (40.3 ± 6.1 in DM, 37.2 ± 6.1 in controls; P < 0.001) and Hex (39.9 ± 5.2 in DM, 44.6 ± 6.0 in controls; P < 0.001). The longer duration of DM ( > 10 years) and poor glycaemic control (HbA1c > 7.5%) were associated with similar results. A significantly reduced ECD (P < 0.001) and Hex (P = 0.001) and higher CV (P = 0.007) and CCT (P = 0.01) was noted when assessed against various stages of DR. Multivariate analysis showed that increasing age was significantly associated with lower ECD (P < 0.001), Hex (P < 0.001), and CCT (P = 0.004); and a higher CV (P < 0.001). DM has deleterious effects on corneal endothelium and thickness. The presence of DR may further warrant a thorough corneal evaluation, especially when planning intraocular surgery.