As we grow older, eyesight isn't what it used to be. Fortunately, eyeglasses or contact lenses can fix most garden-variety vision problems. But for many Americans, the solution isn't that simple. An estimated 1.75 million Americans age 40 and older have age-related macular degeneration (AMD), a disease that gradually and stealthily destroys central vision. AMD is the leading cause of vision impairment and blindness in Americans 65 and older. More than seven million older people are at high risk for developing the condition. There is no cure.
Now, antioxidants and drugs bring renewed hope. In 2001, the Age-Related Eye Disease Study (AREDS), sponsored by the National Eye Institute, found that taking a high dose formulation of vitamin C, vitamin E, beta-carotene-so-called antioxidants-and zinc may reduce the risk of progressing to wet AMD by 25 percent. In October '06, researchers reported that the drug ranibizumab (Lucentis) prevented vision loss and produced marked improvements in vision in about one-third of people with active wet AMD, the more serious form of the disease. Study results were published in the New England Journal of Medicine.
There are two types: Dry AMD, the most common form, is caused by the breakdown of light-sensitive cells in the macula, or center of the retina. Over time, central vision becomes blurred and is eventually lost. A red flag for the condition is the appearance of drusen, or yellow deposits, under the retina, detected during an eye exam. The more drusen a person has and the larger they are, the more likely dry AMD will occur.
Dry AMD typically affects both eyes but can progress at different rates in each eye. As a result, you may have advanced dry AMD in one eye and not be aware of it if you have an early form of the condition in the other eye. An early sign of dry AMD is slightly blurred vision. You may need more light to read, for example, or have trouble recognizing faces. Dry AMD can convert to wet AMD, the more rapidly progressive form of the disease.
Wet AMD progresses rapidly and is always "advanced." In fact, there is no early stage of the condition. It's caused by the growth of abnormal and fragile blood vessels under the macula. These blood vessels often leak blood and fluid, damaging the macula. A hallmark symptom: Straight lines appear crooked or wavy. A blind spot may appear in the center of your vision.
You should be checked for AMD if you are older than 50 and have noticed a change in your central vision. Typically, your ophthalmologist will perform a comprehensive eye exam. He or she will also have you look at a checkerboard-like grid, called the Amsler grid. With one eye covered, you'll look at the black dot in the center. If the lines appear wavy or any seem to be missing, you could have AMD. You may also undergo a fluorescein angiogram to pinpoint leaky blood vessels. This involves injecting a dye into your arm and taking pictures as the dye travels through blood vessels in the retina.
If you are at high risk for advanced dry AMD, your doctor may recommend that you take the AREDS formulation that can reduce the risk of developing advanced AMD by about 25 percent..The AREDS' findings were based on a formulation consisting of 500 milligrams of vitamin C; 400 IU of vitamin E; 15 mg of beta-carotene; 80 mg of zinc as zinc oxide; and 2 mg of copper as cupric oxide. (Copper helps prevent copper deficiency anemia, which can be caused by high levels of zinc.)
If you have wet AMD, your doctor may prescribe ranibizumab. Researchers found that 94.5 percent of patients treated with 0.3 mg of ranibizumab and 94.6 percent of those treated with 0.5 mg had lost fewer than 15 letters (on the eye chart) from their visual acuity at the 12-month mark. In fact, vision improved by 15 or more letters in nearly 25 percent of people given 0.3 mg of the drug and by nearly 34 percent in those given a 0.5 mg dose. Patients received monthly eye injections of the drug.
Wet AMD can also be treated with laser therapy, to destroy leaky blood vessels; photodynamic therapy with verteporfin (Visudyne), and pegaptanib sodium (Macugen). Photo-dynamic therapy involves injecting a drug into an arm vein. The drug is absorbed by the abnormal blood vessels in the eye that cause wet AMD. Next, a cold laser is shone into the eye that activates the drug, thus destroying the blood vessels. Typically, the therapy is performed six to seven times over two to three years. Macugen, like Lucentis, is injected into the eye. Both can slow the progression of vision loss.