What are the types of diabetic retinopathy?

There are generally two stages of diabetic retinopathy: Nonproliferative and proliferative. Nonproliferative diabetic retinopathy (NPDR), the most common type of diabetic retinopathy, occurs when the blood vessels in a person’s retina weaken and tiny bulges protrude from their walls. Proliferative diabetic retinopathy (PDR) is the more severe type of diabetic retinopathy and occurs with the growth of abnormal blood vessels. This may lead to bleeding or scar tissue formation, possibly causing detachment of the retina and permanent vision loss.  Both NPDR and PD can cause diabetic macular edema (DME) which can cause central vision loss.