diabetic retinopathy
Summary
Diabetic retinopathy is a progressive microvascular complication of diabetes mellitus affecting retinal blood vessels, leading to vision impairment and potential blindness. It progresses from nonproliferative (background) to proliferative stages, with macular edema being a major cause of vision loss. Regular ophthalmologic screening and glycemic control are essential for prevention and management.
Detail
Diabetic retinopathy results from chronic hyperglycemia causing retinal capillary damage through multiple mechanisms including advanced glycation end products (AGEs), protein kinase C activation, and oxidative stress. The condition progresses through stages: mild nonproliferative (microaneurysms, dot-blot hemorrhages), moderate nonproliferative (cotton wool spots, venous beading), severe nonproliferative (extensive hemorrhages, intraretinal microvascular abnormalities), and proliferative (neovascularization due to VEGF release from ischemic retina). Diabetic macular edema can occur at any stage and involves fluid accumulation in the macula due to breakdown of the blood-retinal barrier. Risk factors include duration of diabetes, poor glycemic control (HbA1c >7%), hypertension, hyperlipidemia, pregnancy, and nephropathy. Treatment includes laser photocoagulation, anti-VEGF injections (bevacizumab, ranibizumab), and vitrectomy for advanced cases. The condition is asymptomatic in early stages, making regular dilated eye exams crucial for early detection.
Sources
- Harrison's Principles of Internal Medicine
- Kanski's Clinical Ophthalmology
- American Diabetes Association Clinical Practice Recommendations
- First Aid for the USMLE Step 1
- UpToDate Clinical Decision Support
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