Aim: To detect retinal changes in patients with type 2 Diabetes prior to vascular signs without diabetic retinopathy or with mild non proliferative diabetic retinopathy. Methods: A crosssectional study was performed in three groups: 1. Patients without diabetes (Group A), 2. Patients with type 2 diabetes without diabetic retinopathy (Group B), 3. Patients with diabetes with mild diabetic retinopathy (Group C). Analysis of retinal layers was performed using Topcon 3D OCT. Macular scans were analyzed with regard to: retinal nerve fiber layer thickness, central subfoveal retinal thickness and average macular thickness. Results: In total, 60 patients were included in this study, of which 16 (26.67%) were classified into control group (Group A), 28 (46.67%) classified as diabetic patients with no diabetic retinopathy (Group B) and 16 (26.67%) classified as mild diabetic retinopathy (Group C). Quantitative analysis with using Topcon 3D OCT showed that the mean retinal nerve fiber layer was thinner in diabetics without diabetic retinopathy group when compared to controls. Statistically significant reduction in average retinal thickness in mild diabetic retinopathy group compared to control. Also indicated reduction in retinal nerve fiber layer in diabetic without diabetic retinopathy and eyes with mild diabetic retinopathy, compared to controls. Both the results were statistically significant. Conclusions: Our study found reduction in thickness of retinal nerve fiber layer in patients with diabetes without diabetic retinopathy, which suggests neuroretinal changes before vascular signs of diabetic retinopathy.

Keywords: Diabetes Mellitus; Diabetic Retinopathy; OCT; Optical Coherence Tomography; Macula; Retina; Neuronal; Neurodegeneration.