Macular Degeneration

Also known as: age-related macular degeneration (ARMD or AMD), age-related maculopathy (ARM), aged macular degeneration, and senile macular degeneration

Macular degeneration, which is atrophy or degeneration of the macular disk, accounts for about 12% of all cases of blindness in the United States and for about 17% of new cases of blindness. It's one of the causes of severe irreversible loss of central vision in people over age 50.

Two types of age-related macular degeneration occur. The dry, or atrophic, form is characterized by atrophic pigment epithelial changes and is most often associated with a slow, progressive distortion of straight lines or edges and central visual loss. The wet, or exudative, form causes rapid onset of visual impairment. It's characterized by subretinal neovascularization that causes leakage, hemorrhage, and fibrovascular scar formation, which produce significant loss of central vision.

Causes

Age-related macular degeneration results nom the formation of drusen (clumps of epithelium) or subretinal neovascular membrane in the macular region. No predisposing conditions have been identified. However, it may be hereditary.

Underlying pathologic changes occur primarily at the level of the retinal pigment epithelium, Bruch's membrane, and choriocapillaris in the macular region. Drusen (bumps), which are common in elderly people, appear as yellow deposits beneath the pigment epithelium and may be prominent in the macula.

Signs and symptoms

The following are the most common symptoms of AMD. However, each individual may experience symptoms differently. Symptoms may include:

• blurry or fuzzy vision
• difficulty recognizing familiar faces
• straight lines, such as sentences on a page, telephone poles, and the sides of buildings, appear wavy
• a dark or empty area (blind spot) appears in the center of vision
• rapid loss of central vision - vision necessary for driving, reading, recognizing faces, and performing close-up work

The presence of drusen , tiny yellow deposits in the retina, is one of the most common early signs of AMD. These will be visible to your physician during an eye examination. While the presence of drusen alone does not indicate the disease, it may mean the eye is at risk for developing more severe AMD.

The symptoms of AMD may resemble other eye conditions. Consult a physician for diagnosis.

Diagnosis

The following tests are used to diagnose macular degeneration:

• indirect ophthalmoscopy: may reveal gross macular changes.
• Amsler's grid: reveals central visual field distortion
• I. V. fluorescein angiography: may show leaking vessels as fluorescein dye flows into the tissues nom the subretinal neovascular net.

Treatment

There is no proven medical therapy for dry macular degeneration.  Laser photocoagulation reduces the incidence of severe visual loss in patients with subretinal neovascularization.

Recently, photodynamic therapy has proven to be effective in stopping abnormal blood vessel growth in some patients with wet AMD. This new type of laser treatment is far less damaging than laser photocoagulation and is the treatment of choice in many cases.

Eating a diet that is rich in the antioxidants beta carotene; vitamins A, C and E; and the minerals selenium and zinc may help prevent or slow the progression of macular degeneration. Good sources of antioxidants include citrus fruits, cauliflower, broccoli, nuts, seeds, orange and yellow vegetables, cherries, blackberries, and blueberries. Other treatments still being studied include drug therapies to slow the growth of blood vessels, subretinal surgery, and photodynamic therapy (PDT). Your doctor can discuss the options with you and recommend the best type of treatment for your condition.

Prevention

There is no known effective prevention. If you have a family history of macular degeneration, avoid all use of tobacco. Studies have shown that vitamin use and good nutrition may reduce the risk of developing macular degeneration.