Getting Clear on Genetic Tests for Macular Degeneration
Age-related macular degeneration (AMD) is the leading cause of vision loss in people over age 50. This irreversible disease damages the macula, located in the middle of the eye. It’s the area responsible for central vision, which enables us to see objects that are straight ahead. Losing the middle field of vision makes it difficult, and eventually impossible, to read, recognize faces, cook, or drive.
Losing any part of vision is, of course, very scary. That might make it especially tempting to get a genetic test for AMD to see if you are at risk. After all, healthcare providers constantly remind us that it’s better to catch problems early when treatments can be more effective. But despite the many ads that claim they can genetically detect AMD, there are currently none that predict AMD with any certainty. Therefore, the American Academy of Ophthalmology advises against genetic tests for AMD, and insurance generally won’t cover the cost.
“It’s also difficult to know what is genetic, what is age-related, and how the environment is affecting our eyes,” says ophthalmologist Gad Heilweil, MD, UCLA Doheny Eye Institute. “Many genetic factors have been discovered in the last two years, and we maybe understand 50 percent about the genetic part of this disease.”
WHAT YOU SHOULD KNOW
With prompt detection of AMD, there are steps you can take to further reduce your risk of vision loss. Age is a risk factor as are:
➢ Smoking. Any smoking doubles the risk of AMD.
➢ Race. Caucasians are more at risk than African-Americans or Hispanics.
➢ Family history and genetics. People with a family history of AMD are at higher risk.
➢ Age. AMD typically begins after the age of 60.
Stem Cell Studies Underway
Multiple studies using stem cells are attempting to find solutions to other forms of AMD, including geographic atrophy, for which there are currently no treatments. For example, researchers from the UCLA Jules Stein Eye Institute used specialized eye cells created from stem cells to treat severe vision loss in 18 patients with dry age-related macular degeneration and another eye disease. The treatment restored some sight in more than half of the patients. The study appeared in the Oct. 14, 2014 issue of The Lancet. Research is ongoing.
While there currently is no cure for AMD, there are treatments that can slow down the progression of the disease.
Main Types of AMD: Wet and Dry
The most common type of AMD is dry macular generation. As the macula begins to thin in this early stage of AMD, it sometimes, but not always, causes the loss of central vision. Typically, when vision loss occurs, it does so very slowly, and tends to happen to both eyes, which makes the change much more obvious. With gradual occurrence in one eye, however, the other eye can compensate, and you may not even realize that you’re losing any vision. That can be especially dangerous when driving, as you may not even see a car because of your AMD-induced blind spot. Annual exams can dectect AMD in the early stages, which can lower your risk for getting wet AMD.
According to Dr. Heilweil, there is a five percent chance of developing wet AMD. In the past, most patients went legally blind if they got wet macular degeneration. Now, they can be treated with eye injections.
“In 90 percent of the patients, it stops the disease from getting worse,” says Dr. Heilweil. “In 30-40 percent of patients it improves vision.”
Wet AMD (also called neovascular) is when abnormal blood vessels grow beneath the macula. The vessels can leak, which damages the macula. Vision loss is typically more sudden, rapid and severe with wet AMD.
Treatment and Prevention of AMD
Studies show that taking high-dose vitamins and minerals can slow the progression of dry macular degeneration. The first Age-Related Eye Disease Study (AREDS) trial showed that a combination of vitamin C, vitamin E, beta-carotene, zinc, and copper can reduce the risk of late AMD by 25 percent. A number of manufacturers offer supplements based on these studies. These are the clinically significant doses from these trials:
- 500 milligrams (mg) of vitamin C
- 400 international units of vitamin E
- 80 mg zinc as zinc oxide (25 mg inAREDS2)
- 2 mg copper as cupric oxide
- 15 mg beta-carotene, or 10 mg lutein and 2 mg zeaxanthin
Consult with your physician before taking supplements, especially high-dosage ones. According to studies, it’s pointless to take these supplements if you don’t have AMD.
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