In diabetes, damage to which eye structure commonly leads to blindness?

• A. lens
• B. cornea
• C. retina
• D. iris

Answer: (C)

Damage to the retina is the mechanism by which diabetes most commonly causes blindness. The retina is the light-sensitive layer at the back of the eye that converts light into neural signals. In diabetes, chronic high blood sugar damages the tiny retinal vessels, leading to leakage, swelling, and areas of ischemia. This diabetic retinopathy can progress to macular edema and, in more advanced stages, fragile new vessels that bleed into the retina or the vitreous, causing severe vision loss or blindness if untreated. While other eye structures like the lens can develop issues such as cataracts in diabetes, they are not the typical path to blindness seen with diabetic retinopathy. Regular eye exams and tight glucose control help prevent this damage.