Animal models of DR demonstrating increased vascular permeability (A) and retinal neovascularization (B). (A) Intraperitoneal injection of streptozocin to mice leads to hyperglycemia in 2 ~ 3 days and increased vascular permeability ensues in a week. Flat-mounted retina after the intravenous injection of FITC-dextran evidences diffuse leakage of retinal vessels. (B) Exposure to hyperoxia from P7 to P12 results in retinal neovascularization, which starts at P14 and peaks at P17. Flat-mounted retina after the intravenous injection of FITC-dextran demonstrates central ischemic retina with small vascular tufts at the junction between vascularized and avascular retina.