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A Quick Guide to Age-Related Macular Degeneration and Vision Loss

AMD damages cells in the eye's macula, the center portion of the retina that allows you to see objects clearly. There is no cure, but some cases are treatable and vision can often be stabilized or improved with early detection and treatment.
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Robin N. Ginsburg, MD
Director of Vitreoretinal Service
Assistant Professor, Ophthalmology
Icahn School of Medicine at Mount Sinai

A Quick Guide to Age-Related Macular Degeneration and Vision Loss

Our sight is important to the way we communicate with the world. Unfortunately, as we grow older, we may start to experience reduced vision. One common cause of age-related vision loss is an eye disease called macular degeneration, for which early detection offers the best chance of preserving vision.

What Is Age-Related Macular Degeneration?

Age-related macular degeneration (AMD) is a leading cause of vision loss in people over age 50 in the United States, affecting about 15 million Americans. It can cause mild to severe loss of vision but never results in total blindness.

AMD damages cells in the eye's macula, the center portion of the retina that allows you to see objects clearly. There is no cure, but some cases are treatable and vision can often be stabilized or improved with early detection and treatment.

There are two forms of AMD, which can develop in one or both eyes.

Dry AMD

Most patients have dry AMD, the less severe type. While not everyone experiences symptoms initially, early signs of dry AMD may include the following:

• Mildly distorted vision where straight lines appear wavy;
• Difficulty adjusting from bright to dim light;
• Inability to see subtle differences in contrast;
• Reduced sharpness of vision;
• More light required for reading.

Dry AMD tends to worsen slowly over many years. It can rarely advance to severe loss of central (straight-ahead) vision caused by gradual deterioration of tissue under the retina or by changing to the wet type of AMD.

Wet AMD

Sometimes, dry AMD progresses to the more serious wet AMD, which accounts for 10 percent to 15 percent of cases. Wet AMD is associated with rapid and severe loss of central vision caused by the growth of abnormal blood vessels and fluid beneath the retina. Patients may suddenly develop a blind spot and notice letters missing from printed words when reading, or be unable to see facial details when looking directly at someone.

Risk Factors

We don't know what causes age-related macular degeneration, but genetic and environmental factors are likely involved. AMD is more common in women than men, and you are at increased risk if you:

• Are over 50;
• Have a family history of the disease;
• Smoke;
• Are of European descent;
• Have light-colored eyes;
• Have high blood pressure, high cholesterol, or cardiovascular disease.

Diagnosis

To catch early signs of age-related eye diseases like AMD, the American Academy of Ophthalmology recommends that everyone have a comprehensive, baseline eye examination by age 40. This should include dilating (widening) the pupils and be performed by a doctor qualified to evaluate the retina. Patients with a family history of macular degeneration or who are experiencing symptoms, such as distorted, blurry, or decreased vision, should see an ophthalmologist or retina specialist. If nothing of concern is found on examination, annual check-ups thereafter are appropriate. However, if risk factors or symptoms are noted, you should be seen more frequently, as judged by your doctor.

Treatment of Dry AMD

Unfortunately, there is no approved treatment for dry AMD. However, high-dose micronutrients -- specifically vitamins C and E, lutein, zeaxanthin, and zinc -- are recommended for those patients at high risk of progressing to advanced AMD. A major clinical trial found this daily regimen to decrease such patients' risk by about 25 percent, thereby slowing disease progression and reducing vision loss. Your doctor can tell you if you might benefit from the micronutrient formula.

Many clinical trials are now focused on slowing the progress of dry AMD with medications delivered into the body or directly into the eye.

Treatment of Wet AMD

While nothing can be done for advanced dry AMD, it is crucial to detect the wet form early because approved treatments are available and have been shown to stabilize vision.

The treatment of choice involves periodic doctor-administered injections of medication directly into the affected eye(s). This temporarily slows or stops the disease process. The three main drug therapies work equally well, but there is a large price difference among them, so be sure to ask your insurance company about coverage.

The medications do not cure AMD, so patients must get injections first monthly, then on a schedule determined by subsequent examinations. Researchers are investigating long-acting delivery systems, as well as alternate ways of administering the medication.

With treatment, most people's vision will stay about the same or just worsen mildly. Sometimes vision even gets better. Without treatment, patients face more than a 60 percent risk of severe vision loss within two years.

Prevention

Although there is no sure way to prevent AMD, a healthy lifestyle may lower the risk of developing it. This includes not smoking; eating a healthy diet rich in green, leafy vegetables; exercising regularly; maintaining a healthy weight; and controlling your blood pressure and cholesterol. I also recommend that older patients take a daily vitamin tailored to seniors. Wearing sunglasses has not proven beneficial, but it can't hurt.

Living with AMD

It is vital that those diagnosed with age-related macular degeneration monitor symptoms and see an eye doctor as soon as any change in vision is noticed. Your doctor may recommend Amsler Grid testing, a home monitoring technique using a grid of straight lines to detect worsening vision. Regular eye exams are also important.

Patients whose vision is markedly reduced should see a low-vision specialist, who can recommend such aids as specific eyeglasses, magnifiers, and reading devices to help work around visual deficits. Reading may be aided by large-print books, audiobooks, and electronic devices like iPads and Kindles that allow you to increase the text size.

It may help to remember that people do not go completely blind from AMD. Severe visual loss caused by macular degeneration affects only the central vision; the side vision stays intact. With encouragement, assistance, and motivation, even patients whose low vision interferes with activities like reading or driving can still function and maintain a healthy, active, and fulfilling lifestyle.