Diabetic retinopathy is an eye disorder caused by diabetes (see page 365), a chronic disease that can damage blood vessels, including those in the eye. A leading cause of blindness in adults in the United States, diabetic retinopathy is caused by changes in the blood vessels of the retina, the light-sensitive membrane that lines the back of the eye. In some people, the blood vessels leak fluid. In others, abnormal new blood vessels grow on the surface of the retina. These abnormal blood vessels can bleed and leak into the vitreous humor (the jellylike substance that fills the center of the eye), preventing light from passing through to the retina. The abnormal blood vessels and bleeding also can produce scar tissue that pulls the retina away from the back of the eye, causing a detached retina. Anyone with diabetes can develop diabetic retinopathy, and the longer a person has diabetes, the more likely he or she is to develop this disorder. Nearly half of all people with diabetes will develop diabetic retinopathy.
There may be no obvious symptoms in the early stages of the disease, but some people with diabetic retinopathy experience blurred vision when the macula (the part of the retina that provides sharp central vision) swells because of the leaking fluid. Abnormal blood vessels that have grown on the surface of the retina can cause symptoms such as blurred vision, seeing spots, vision that alternates between being normal and diminished, pain in the eyes, and sudden loss of vision. If you experience any of these symptoms, contact your ophthalmologist immediately. In some cases, vision may not become impaired until the disease is severe. That is why regular (at least yearly, or more often if recommended by your physician) eye examinations performed by an ophthalmologist are so important for people with diabetes.
During the eye examination, the ophthalmologist will dilate your pupils with eyedrops and then examine your retina using an ophthalmoscope (a handheld viewing instrument that projects a very bright light onto the back of the eye). He or she will look for leaking fluid, abnormal bleeding, or new blood vessel growth on the retina. Early detection and treatment of diabetic retinopathy go a long way toward preventing vision loss and blindness and minimizing potential vision problems.
The best way to prevent diabetic retinopathy and to slow its progression is to 393
consistently control the level of glucose in your blood (see page 368) through Eyes diet, exercise, medication, and insulin, if necessary. It also is important to keep your blood pressure within the normal range (see page 219). In some cases the ophthalmologist may recommend laser surgery in which a highly concentrated beam of light is directed onto the retina either to shrink abnormal blood vessels or to seal leaking blood vessels. This procedure can be performed in the doctor's office or in an outpatient facility. Laser surgery can reduce the risk of severe vision loss from diabetic retinopathy, but it may not restore vision that has already been lost.
A type of microsurgery (delicate surgery performed under a microscope) called vitrectomy may be used for advanced cases of diabetic retinopathy, in which the vitreous humor has become filled with blood. In this procedure the vitreous humor is removed and replaced with a clear solution. Vitrectomy may take several hours to complete and is performed in an operating room using either local or general anesthesia. The procedure can cause discomfort. Recovery time varies, depending on the extent of the problem.
Surgery to reattach the retina may be needed if scar tissue causes the retina to become detached from the back of the eye. The procedure is performed using either local or general anesthesia and may be combined with laser surgery or vitrectomy. Surgery may take several hours to complete and is performed in an operating room. The procedure can cause discomfort.
People who have diabetes are also at risk for other eye diseases. They are twice as likely to develop a cataract (see page 390) as people without diabetes, and the cataracts tend to develop at an earlier age. Glaucoma (see page 388) also occurs in people with diabetes twice as often as in other adults. The longer you have diabetes, the higher your risk of developing glaucoma.
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