Diabetic Retinopathy

Diabetic retinopathy is retinal damage caused by chronic diabetes-related injury to small blood vessels. The retinal capillaries become fragile and leaky, while other areas close off and become ischemic. Leakage produces microaneurysms, retinal hemorrhages, lipid deposits, and edema. Ischemia stimulates vascular endothelial growth factor (VEGF), which drives the growth of abnormal new vessels. Nonproliferative diabetic retinopathy (NPDR) is the earlier stage. Retinal findings may be present even when vision is normal because the macula—the area responsible for sharp central vision—has not yet been affected. Diabetic macular edema (DME) occurs when fluid accumulates in or near the macula. The patient may describe blurred central vision, difficulty reading, faded colors, or straight lines that appear wavy. DME can occur with either nonproliferative or proliferative disease. Center-involved DME threatens central visual acuity and often requires treatment. Proliferative diabetic retinopathy (PDR) develops when ischemic retina releases enough VEGF to produce neovascularization. These new vessels are weak and grow where they do not belong, including on the retinal surface or into the vitreous. They can bleed suddenly, causing vitreous hemorrhage, or create scar tissue that...