Two Kinds of Diabetic Retinopathy

In diabetic retinopathy the blood vessels of the retina become abnormal and cause the problems that people with diabetes have with their eyesight. Normally, the blood vessels in the retina do not leak. But with diabetes, the retinal blood vessels can develop tiny leaks. These leaks cause fluid or blood to seep into the retina. The retina then becomes wet and swollen (called "thickened" in some scientific studies) and cannot work properly. The form of diabetic retinopathy caused by leakage of retinal blood vessels is called nonproliferative (or background) diabetic retinopathy. We will use the term NPDR for Nonproliferative Diabetic Retinopathy throughout the rest of this discussion.

Another problem with the retinal blood vessels in diabetes is that they can close. The retinal tissue, which depends on those vessels for nutrition, will no longer work properly. The areas of the retina in which the blood vessels have closed then foster the growth of abnormal new blood vessels, called neovascularization. This can be very bad for the eye because neovascularization can cause bleeding and scar tissue that can result in blindness (total loss of vision). The form of diabetic retinopathy caused by closure of the blood vessels and in which neovascularization develops (proliferates) is called proliferative diabetic retinopathy. We will use the term PDR for Proliferative Diabetic Retinopathy throughout the rest of this discussion.