Diabetic retinal neurodegeneration associated with synaptic proteins and functional defects: A systematic review

Diabetic retinopathy (DR) is the most common ophthalmological complication of diabetes mellitus (DM) and a leading cause of preventable visual impairment. In DM, retinal neurodegenerative changes precede microvascular changes which can be assessed by electrophysiological and advanced imaging techniques. Studies measuring retinal neurodegenerative changes in DM were systematically evaluated in this review. Included studies have assessed retinal neurodegeneration in diabetic rodents by combining clinically used diagnostic techniques and molecular assays. Significant impairment was noticed in electrophysiology data in the diabetic retina as compared to the non-diabetic retina. Also, a significant reduction in synaptic protein levels was noticed in the diabetic retina compared to the non-diabetic retina. Even though retinal neurodegeneration was noticed, no vascular abnormalities were seen in the diabetic retina. However, little is known about molecular mechanisms behind diabetic retinal neurodegeneration (DRN), which explains the need for further investigation to detect DR in the early stages of diabetes.