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 in the back of the eye that senses light and helps send images to the brain. Diabetic retinopathy is the leading cause of blindness the United States. Diabetes can also affect vision by development of cataracts, glaucoma, macular edema and retinal detachment.
- Blurred vision and slow vision loss over time
- Shadows or missing areas of vision
- Trouble seeing at night
Many patients with early diabetic retinopathy may have no symptoms and hence regular eye exams should be performed.
There are two types of diabetic retinopathy: nonproliferative diabetic retinopathy (NPR) and proliferative diabetic retinopathy (PDR).
NPDR, commonly called background retinopathy, is an early stage of diabetic retinopathy. In this stage, tiny blood vessels in 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. Vision is affected as a result of macular edema or macular ischemia.
PDR is present when abnormal new vessels begin to grow on the su8rface 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 blood vessels closed. Unfortunately, the new blood vessels do not resupply the retina and are often accompanied by scar tissue that may cause wrinkling or detachment of the retina.
PDR may cause more severe vision loss than NPDR because it can affect both central and peripheral vision.
People with diabetes should schedule examinations at least once a year. More often may be necessary after a diagnosis of diabetic retinopathy.