Diabetic retinopathy: Causes
Diabetic retinopathy: Causes
Feb. 13, 2008
By Mayo Clinic Staff
When you have diabetes, your body doesn't use sugar (glucose) properly. If your blood sugar level is too high, your natural lens may swell — which can blur your vision. Eventually, too much sugar in your blood can damage the tiny blood vessels (capillaries) that nourish the retina. This can result in diabetic retinopathy.
Diabetic retinopathy is usually classified as early or advanced.
* Early diabetic retinopathy. Nonproliferative diabetic retinopathy (NPDR) is the most common type of diabetic retinopathy. It can be described as mild, moderate or severe. When you have NPDR, the walls of the blood vessels in your retina weaken. Tiny bulges protrude from the vessel walls, sometimes leaking or oozing fluid and blood into the retina. These bulges are called microaneurysms. As the condition progresses, the smaller vessels may close entirely and the larger retinal veins may begin to dilate and become irregular in diameter. Nerve fibers in the retina may begin to swell. Sometimes the central part of the retina (macula) begins to swell, too. This is known as macular edema.
* Advanced diabetic retinopathy. Proliferative diabetic retinopathy (PDR) is the most severe type of diabetic retinopathy. When you have PDR, abnormal blood vessels grow in the retina. Sometimes the new blood vessels grow or leak into the clear, jelly-like substance that fills the center of your eye (vitreous). Eventually, scar tissue stimulated by the growth of new blood vessels may cause the retina to detach from the back of your eye. If the new blood vessels interfere with the normal flow of fluid out of the eye, pressure may build up in the eyeball. This can damage the nerve that carries images from your eye to your brain (optic nerve).
© 1998-2009 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "EmbodyHealth," "Reliable tools for healthier lives," "Enhance your life," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.
