The retinal vascular network of experimental diabetic rats was studied by trypsin digestion 6 months after an elevation in blood sugar level to 400-600 mg/dl, when the retinal capillaries began to show pericyte loss, with appearance of capillary microaneurysms, acellular capillaries, venular obstruction, capillary varicosis and diametral irregularity. The possible mechanism of these changes were discussed.