Which statement best describes the pathophysiology of diabetic retinopathy?

• A. When blood sugar is high, small retinal vessels leak fluid and protein, potentially affecting the macula and causing blurry vision
• B. It is caused by increased intraocular pressure damaging the optic nerve
• C. It results from retinal detachment due to high blood pressure
• D. It is due to abnormal corneal swelling from diabetes

Answer: (A)

Chronic high blood sugar damages the retinal microvasculature, leading to breakdown of the blood-retinal barrier. This causes leakage of fluid and plasma proteins from the small retinal vessels, especially around the macula, producing macular edema and blurred vision. Over time, capillary nonperfusion and ischemia promote VEGF-driven neovascularization in proliferative diabetic retinopathy, which increases the risk of hemorrhage and tractional retinal detachment. This description specifically captures the vascular leakage and edema central to diabetic retinopathy. Other statements describe conditions that are not this disease process: increased intraocular pressure affects the optic nerve in glaucoma, retinal detachment is not caused by hypertension in this context, and corneal swelling is a front-of-eye issue unrelated to the retinal microvasculature.