Long-Term Damage to Eyes Diabetic retinopathy is damage to the tiny blood vessels within the retina of the eye due to high blood sugar levels over time. This can cause progressive and permanent vision loss. Diabetic retinopathy is the most common cause of new blindness in people between 20 and 74. This image shows pools of blood, or hemorrhages, in the retina. Food can either contribute to longevity, or it can be the slowest form of poison. Just don't eat that piece of cake.