Correlation of peripapillary retinal nerve fiber layer thickness and ganglion cell complex thickness with the severity of diabetic retinopathy

Abstract

Purpose The aim of this study was to verify the role of peripapillary retinal nerve fiber layer thickness (RNFLT) and ganglion cell (GC) complex thickness in early detection of diabetic retinopathy (DR) using spectral domain optical coherence tomography (SD-OCT). Patients and methods This was a cross-sectional, case–control study. Twenty-nine eyes of patients with type 2 diabetes mellitus, either with no DR (16 eyes, group 1) or mild nonproliferative DR (13 eyes, group 2), and 14 eyes of healthy controls (group 3) were enrolled in the present study. All participants had a complete ophthalmic examination, including SD-OCT. Ganglion cell inner plexiform layer (GCIPL) and RNFLT values were calculated after automated segmentation of SD-OCT scans. Results Significantly reduced GCIPL and RNFLT values were demonstrated in both diabetic patients’ groups compared with healthy controls. Mean GCIPL thickness was 97.5 µm in group 1, 96.9 µm in group 2, and 107.9 µm in group 3 (P=0.04 and 0.04 compared with healthy controls, respectively). Average RNFLT was 104.12±9.6 µm in diabetes patients with no DR (group 1), 100.46±12.86 µm in group 2, and 111.35±6.15 µm in controls (P=0.02 and 0.009 compared with healthy controls, respectively). Conclusion Significantly reduced GCIPL and RNFLT values were demonstrated in both no DR and mild nonproliferative DR groups compared with healthy controls. This indicates that retinal neuronal degeneration occurs in the early stages of DR, even before microvascular abnormalities are visible.