Diabetic Retinopathy
Definition
Diabetic retinopathy is damage to the blood vessels in the eye caused by diabetes and is the leading cause of new blindness among American adults aged 20 to 65.
Description
Diabetic retinopathy is caused by diabetes. It affects the retina - the light-sensitive tissue at the back of the eye that transmits visual messages to the brain. Damage to this delicate tissue may result in visual impairment or blindness. Diabetic retinopathy is broadly classified as nonproliferative and proliferative.
Nonproliferative diabetic retinopathy is characterized by dilation of veins, microaneurysms (weakened vessels), retinal hemorrhages, and retinal edema (swelling). Proliferative diabetic retinopathy is characterized by neo-vascularization (new blood vessel formation).
Often, diabetic retinopathy begins with a slight deterioration in the small blood vessels of the retina. Portions of the vessel walls balloon outward and fluid starts to leak from the vessels into the surrounding retinal tissue. Generally, these initial changes in the retina cause no visual symptoms. However, they can be detected by an eye specialist through appropriate examination. In many people with diabetic retinopathy, the disease remains mild and never causes visual problems. But in some individuals, continued leakage from the retinal blood vessels leads to macular edema. This is a build-up of fluid in the macula - the part of the retina responsible for the sharp, clear vision used in reading and driving. When critical areas of the macula become swollen with excess fluid, vision may be so badly blurred that these activities become difficult or impossible. Some people with diabetes develop an even more sight-threatening condition called proliferative retinopathy. It may occur in people with macular edema, but also can develop in those without it. In proliferative retinopathy, abnormal new blood vessels grow on the surface of the retina. These fragile new vessels can easily rupture and bleed into the middle of the eye, blocking vision. Scar tissue also may form near the retina, ultimately detaching it from the back of the eye. Severe visual loss, even permanent blindness, may result. But this happens only in a small minority of people with diabetes.
Causes
Approximately 40 percent of all people with diabetes have at least the mild signs of diabetic retinopathy. About 3 percent have suffered severe visual loss because of this disease. In general, the longer one has had diabetes, the greater are one's chances of developing diabetic retinopathy.
Symptoms
Early diabetic retinopathy causes few, if any, symptoms. Characteristic signs of retinal changes may be seen during examination of the retina. Severe retinopathy causes minor to severe deterioration of visual acuity.
Diagnosis
Patients with diabetes should have at least yearly ophthalmoscopic (eye) examination. Examination by an ophthalmologist (an eye doctor who is an M.D.) is often advisable.
Treatment
Early diagnosis and treatment is critical in order to prevent complications and blindness. Laser treatment may prevent visual loss in many people with diabetic macular edema. In this treatment, called photocoagulation, powerful beams of light from a laser are aimed at leaking retinal blood vessels in the macula. The goal of treatment is to seal the vessels and prevent further leakage. In many patients, this treatment halts the decline in vision or even reverses it. Research also has shown that laser photocoagulation can dramatically reduce the risk of blindness in people who have proliferative retinopathy. For these patients, the laser is not directed at the macula but is aimed at hundreds of spots in other parts of the retina. The purpose of the treatment is to destroy diseased tissue and to stop the retinopathy from getting worse. In fact, the treatment can reduce severe visual loss by 60 percent. A few diabetic retinopathy patients - including some who have had photocoagulation - go blind from massive bleeding inside the eye. Now, ophthalmologists can remove the blood and scar tissue from the center of the eye. This procedure is known as vitrectomy. Following vitrectomy, patients can often see well enough to move around on their own. Occasionally, vision in the operated eye recovers enough for the patient to resume reading or driving.
Prevention
There are ways to prevent or lessen the eye damage caused by diabetes. The Diabetes Control and Complications Trial (see link below) proved that careful control of blood glucose levels may prevent the development of diabetic retinopathy. Regular eye examinations are especially important for young people who have had diabetes for 5 years or longer, for adults at the time of diagnosis, for those who have difficulty controlling the level of sugar in their blood, and for diabetic women who are considering becoming pregnant. All of these people are at increased risk for diabetes-related eye problems.
Questions
What kind of tests need to be performed for diagnosis? Will the test be able to tell how much damage has been done? If there is damage to the blood vessels or retina, is it permanent or reversible? What treatment do you recommend to correct the problem? Are there any complications to this procedure? How successful is the treatment? Am I at risk for other eye diseases?
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