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Diseases & Conditions

Diabetic Retinopathy

Diabetic retinopathy is an eye condition that affects people with diabetes. It occurs as a result of high blood glucose, or sugar, that people with diabetes often have over a prolonged period of time. Too much blood glucose 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 a light-sensitive nerve tissue at the back of the eye. As light enters the front of the eye, the retina converts the light rays into electrical impulses that travel along the optic nerve to a 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 a properly functioning retina, the eye cannot communicate with the brain.

Diabetic retinopathy occurs when diabetes damages the tiny blood vessels in the retina. In the early stages of the disease, (called nonproliferative retinopathy), these blood vessels leak fluid and distort sight. In the more advanced stage, (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 and cloud vision, or may scar and detach the retina.

Anyone with diabetes (Type 1 or Type 2) is at risk of developing diabetic retinopathy. The factors that affect risk include the type of diabetes a person has, how often his or her blood glucose fluctuates, how well-controlled the sugars are, and how long a person has had diabetes.

The National Eye Institute estimates that 40%-45% of all Americans with diabetes are affected by diabetic retinopathy, and 24,000 of these people lose their vision each year.

What happens if diabetic retinopathy is not treated?

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. Retinal detachment can cause permanent blindness if left untreated.

Diabetic retinopathy can also cause macular edema. The macula is the inner 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 signs of diabetic retinopathy, and sight may not be affected until the condition is severe. Sometimes the only signs that something is wrong are the loss of central vision when reading or driving, loss of the ability to see color, and blurred vision. 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.

How is diabetic retinopathy diagnosed?

An eye doctor (ophthalmologist) can detect diabetic retinopathy after conducting a thorough eye exam. The exam will likely include pupil dilation so that the doctor can look for any changes in blood vessels, new blood vessel growth, swelling of the retina, and retinal detachment.

How is diabetic retinopathy treated?

In most cases, laser surgery can prevent significant vision loss associated with diabetic retinopathy.

A procedure called laser photocoagulation can be performed to seal or destroy growing or leaking blood vessels in the retina. Although the procedure is not painful, laser surgery may lower a person's night vision and ability to see color.

In some people with diabetic retinopathy, the blood that leaks from blood vessels in the retina may also leak into the vitreous humor, clouding vision. A surgical procedure called a vitrectomy can be used to remove the blood that has leaked into this part of the eye.

If diabetic retinopathy is diagnosed in time, almost 90% of people with late-stage, or proliferative retinopathy, can be saved from blindness.

Can diabetic retinopathy be prevented?

You can help protect your sight by having your eyes checked at least once a year by an ophthalmologist. Women who have diabetes and become pregnant should have a comprehensive eye exam during the first trimester and close follow-up with an ophthalmologist during pregnancy (this recommendation does not apply to women who develop gestational diabetes).

You can also help slow down the development of diabetic retinopathy by keeping your blood glucose and blood pressure in check.

When should I call the doctor?

Contact your doctor if you:

  • Have black spots in your vision
  • See flashes of light
  • Have "holes" in your vision
  • Have blurred vision

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 2/16/2009...#8591