Age-related macular degeneration, often called ARMD, is the leading cause of visual impairment in senior citizens in America. According to Prevent Blindness America, some 13 million Americans have some amount of ARMD. As the name “age-related” suggests, the chances of getting ARMD increase as one gets older, especially past age 65. It also tends to run in families, although having one or even two parents with the disease doesn’t automatically mean their children will develop ARMD.
As the name suggests, the disease causes a degeneration, or breakdown, of the macula. The macula is the center part of the retina responsible for the fine vision needed to read the newspaper or drive. Macular degeneration does not cause total blindness, but the vision may deteriorate to the point where driving and reading become difficult or impossible.
There are two types of macular degeneration: dry and wet. Dry macular degeneration accounts for about 90% of cases. Dry macular degeneration begins with the development of yellow-white deposits called drusen in the macula. These drusen are thought to interfere with the normal functioning of the cells of the macula, causing them to degenerate. In some cases, though, drusen deposits can be present for years without leading to ARMD.
Eventually, the changes in the macula from dry ARMD lead to a slow, gradual vision loss over many years. The loss of vision may be so slow that no change is noticed from one year to the next. Patients with dry ARMD generally do not lose central vision entirely, but vision loss may make it difficult to perform tasks that require fine vision. Although extensive research is underway, there is currently no way to reverse the vision loss from ARMD. Some patients may be able to slow or stop vision loss using vitamin therapy.
Wet macular degeneration accounts for about 10% of cases of ARMD. In wet ARMD, abnormal blood vessels grow underneath the macula and leak blood and fluid, causing a decrease in vision. Because the leakage can be sudden, wet macular degeneration can affect vision rapidly. Wet ARMD tends to cause more severe vision loss than dry ARMD, but there are new treatments that may slow down or stop the leakage. While some people can develop wet ARMD directly, many first develop dry ARMD that converts into wet ARMD later.
Treatments for Wet Macular Degeneration
Laser Photocoagulation is a treatment that involves using a laser to destroy the abnormal blood vessels. Once the blood vessels are destroyed, they can no longer leak blood and fluid, and further vision loss is prevented. The laser usually leaves a small blind spot in the vision, and so it can’t be used when the abnormal blood vessels are directly in the center of the macula.
Photodynamic therapy, or PDT, can be used safely when the abnormal blood vessels are directly in the center of the vision. PDT involves the use of a light-activated drug that selectively targets and destroys the blood vessels. The drug is administered by injection and travels to the abnormal blood vessels in the eye. Once the drug has reached the macula, a surgeon aims a “cool” laser at the abnormal blood vessels. With the laser application, the drug becomes active and destroys the abnormal blood vessels without damaging surrounding tissue. Although PDT may work in one treatment, many patients require repeat treatments to completely destroy the abnormal blood vessels.
Macugen is the first FDA-approved treatment of wet ARMD aimed at preventing the growth of nhealthy blood vessels under the macula. Macugen inhibits the action of a protein called VEGF, a necessary cofactor in blood vessel development. The drug is injected into the eye, and typically administered every six weeks. By preventing the growth of new abnormal blood vessels, Macugen can minimize vision loss.
Unfortunately, none of these treatments can restore vision already lost to wet ARMD. That is why it is so important to follow up regularly with your eye care professional if you’ve been diagnosed with wet or dry ARMD.
Treatments for Dry Macular Degeneration
Patients with moderate to advanced cases of dry ARMD can lower their risk of developing wet ARMD and preserve their vision by taking a daily dose of antioxidant vitamins and minerals. This finding is the result of a large clinical trial called the Age-Related Eye Disease Study, or AREDS.
Patients with moderate to advanced dry ARMD who took a daily dose of certain vitamins and minerals had only a 20% risk of developing wet macular degeneration over a five year period, while patients taking a placebo had a 28% risk. The vitamins and minerals used were:
|Vitamin C||500 mg|
|Vitamin E||400 IU|
|Beta Carotene||15 mg|
The AREDS study findings are specific to patients with advanced cases of dry macular degeneration or vision loss from wet macular degeneration in one eye. The AREDS study did not include patients with early dry ARMD or without ARMD. It also did not include newer nutrients such as lutein or zeaxanthin although new studies are currently underway.
Only a doctor can determine whether you would be a candidate to begin antioxidant and zinc therapy. The dosages administered in the AREDS study can have adverse side effects in some patients with pre-existing conditions, so it is strongly recommended patients consult with their doctor before beginning the treatment.