If you have diabetes mellitus, your body does not use and store sugar properly. High blood-sugar levels can damage blood vessels in the retina, the nerve layer at the back of the eye that senses light and helps to send images to the brain. The damage to retinal vessels is referred to as diabetic retinopathy. It is critical that people with diabetes have an annual complete eye examination even if they do not have vision symptoms and show no signs of retinal damage on previous eye examination.
There are two types of diabetic retinopathy: non-proliferative diabetic retinopathy (NPDR) and proliferate diabetic retinopathy (PDR).
- NPDR, commonly known as background retinopathy, is an early stage of diabetic retinopathy. In this stage, tiny blood vessels within the retina leak blood or fluid. The leaking fluid causes the retina to swell or to form deposits called exudates. Many people with diabetes have mild NPDR, which usually does not affect their vision. When the swelling occurs within the center of the macula (the central area that gives sharp vision), laser treatment is necessary to help dry up the fluid. Sometimes shots are given in the eye to dry up the macula.
- PDR is present when abnormal new vessels (neovascularization) begin growing on the surface of the retina or optic nerve. The main cause of PDR is widespread closure of retinal blood vessels, preventing adequate blood flow. The retina responds by growing new blood vessels in an attempt to supply blood to the area where the original vessels closed. Unfortunately, the new abnormal blood vessels do not re-supply the retina with normal blood flow. The new vessels are fragile and are often accompanied by leakage fluid, bleeding, and scar tissue formation that may cause wrinkling or detachment of the retina. Treatment is mandatory to preserve vision. Treatment consists of extensive lasers called panretinal photocoagulation (PRP), supplemented by shots of medication in the eye.