Fundoscopy image of the left eye of a male patient with diabetes that has lead to diabetic retinopathy. The retina is the light-sensitive layer at the back of the eye. Diabetic retinopathy is damage to the blood vessels of the retina caused by the high blood sugar levels associated with diabetes. The damage has also lead to retinal pigment epithelial detachment (circular area at right), where fluid beneath the retinal pigment epithelium causes it to separate from its underlying membrane.