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Eye Health and Diabetic Retinopathy

Diabetic retinopathy occurs as a result of high blood sugar and can cause blindness if left untreated.

Diabetic retinopathy is an eye condition that affects people with diabetes who have high blood glucose, or sugar, over a prolonged period of time. Too much blood sugar can destroy the blood vessels in the back of the eye, preventing the retina from receiving the proper amount of nutrients it needs to maintain vision.

The retina is light-sensitive nerve tissue at the back of the eye. After light enters the eye and reaches the back, the retina converts the light rays into electrical impulses that travel along the optic nerve to part of the brain called the visual cortex. The brain then combines images sent from both eyes to interpret them as a single, three-dimensional image. This allows us to perceive depth and distance. Without the retina, the eye cannot communicate with the brain, making vision impossible.

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Diabetic retinopathy occurs when diabetes damages the tiny blood vessels in the retina. In the early stages of diabetic retinopathy, called nonproliferative retinopathy, these blood vessels leak fluid and distort sight. In the more advanced stage of diabetic retinopathy, called proliferative retinopathy, fragile new blood vessels grow around the retina and in the vitreous humor (a clear substance that fills the eye). If left untreated, these blood vessels may bleed, clouding vision or detaching the retina.

Anyone with diabetes -- both type 1 or type 2 diabetes -- is at risk of developing diabetic retinopathy. However, the type of diabetes a person has, how often the person's blood sugar fluctuates, how well controlled the sugars are, and how long a person has had diabetes all affect his or her risk. The better you control your blood sugar levels, the lower your risk.

The National Eye Institute estimates that 40%-45% of all Americans with diabetes are affected by diabetic retinopathy, and 24,000 of them go blind each year.

What Happens if Diabetic Retinopathy Is Not Treated?

In untreated diabetic retinopathy, scar tissue that forms on the back of the retina as a result of a contraction of the new blood vessels can cause the retina to pull away from the back of the eye. This is called a retinal detachment, or a detached retina. Retinal detachment can cause permanent blindness if left untreated.

Diabetic retinopathy can also cause macular edema. The macula is the most central part of the retina that allows for detail to be seen. When fluid from blood vessels leaks into the macula, it can swell and make vision blurry.

What Are the Symptoms of Diabetic Retinopathy?

There are often no early symptoms of diabetic retinopathy and sight may not be affected until the condition is severe. Sometimes, loss of central vision when reading or driving, loss of the ability to see color, and blurriness of vision are the only signs of diabetic retinopathy. Small spots or floaters may also indicate blood vessel leaks and may clear up in days, weeks, or even months. But, because bleeding often occurs more than once, it is important to have an eye exam each year, and immediately if you experience any of these symptoms.

WebMD Medical Reference

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