What is the basic mechanism by which diabetes causes changes to the eye?

• A. Inflammation of the optic nerve due to infection
• B. Autoimmune attack on retinal ganglion cells
• C. Damage from hyperglycemia causing vascular occlusion with ischemia and neovascularization
• D. Mechanical injury to the cornea

Answer: (C)

Prolonged high blood sugar damages the retinal microvasculature, causing capillary dropout and ischemia. The resulting lack of oxygen triggers the release of VEGF, leading to abnormal new vessel growth (neovascularization). These fragile vessels can bleed and contribute to macular edema, driving vision loss in diabetic retinopathy. The other scenarios describe inflammatory optic nerve disease, autoimmune retinal damage, or mechanical corneal injury, which don’t reflect the vascular occlusion and ischemia-driven neovascular response seen with diabetes.