Clearing Things Up
Macular degeneration is prevalent, but you can help prevent it
Just like the rest of your body wears out as you age, so does your retina. As the population overall gets older, more people are being diagnosed with macular degeneration—a disease of the retina that causes central vision loss, says Dr. Sam Garrett of Virginia Beach Eye Center.
The macula is in the center of the retina, and it allows you to see fine detail, according to the Foundation Fighting Blindness. Light sensing cells convert light that you see into electrical impulses and send those impulses to your brain along the optic nerve. When those light sensing cells degenerate, age-related macular degeneration (AMD) occurs, the foundation says.
Symptoms include a decrease in reading ability and trouble adjusting from light to dark such as driving out of a tunnel into bright sunlight, Garrett says. As macular degeneration progresses, those who have it can’t see the middle of what they are viewing.
“You and I would be sitting across from each other, and if you had bad macular degeneration, you could see everything else in the room but you couldn’t see my face,” Garrett says.
More than 10 million people in the United States, about three percent of the population, have macular degeneration. It’s the most common cause of vision loss in people over 55, according to the Foundation Fighting Blindness.
“Macular degeneration is more and more prevalent as people live longer,” Garrett says.
Family history, which, like aging, you can’t control, is another risk factor, Garrett says. Genetics is a major factor for more than half the people with AMD, the foundation notes. Researchers have discovered several genes that appear to be linked to the disease, the foundation says.
“For people with a family history of macular degeneration—parents, siblings—the risk goes up to 10–12 percent of the population, Garrett says.
The good news? There are risk factors that you can control.
Here’s one more reason to stop smoking.
“Cigarette smokers have a higher incidence of macular degeneration, 10 times the risk of people who don’t smoke,” Garrett says.
Diet is another risk factor. The macula is subject to high light exposure and high blood flow, Garrett says. It also uses oxygen very rapidly, he adds. When oxygen reacts with cells, oxidation occurs, and that can damage cells and tissue.
Population based and identical twin studies have shown that taking certain vitamins and eating a diet with more fish or fish oil and less processed food leads to a lower incidence of AMD, Garrett says. These foods and vitamins are antioxidants and fight back against the tissue-damaging oxidation process.
In 2001, The National Institutes of Health released results of a nationwide Age-Related Eye Disease Study (AREDS) showing that high-dose antioxidant vitamins and minerals (vitamins C, E and beta-carotene as well as zinc and copper) can reduce the risk of progression of advanced AMD by 25 percent and the risk of moderate vision loss by 19 percent.
In 2006, the NIH began a new study, with results expected in 2013, to build on the first study and test the effects by adding omega-3 fatty acids and two plantbased pigments (lutein and zeaxanthin) that accumulate in the retina.
Since smaller studies already suggest that lutein, fish oil and vitamins B and D may help too, Garrett advises patients to consider adding these to their diets.
“It’s heart healthy living,” he says. “Exercise. Eat right. Don’t eat processed foods. Lose weight. Eat lots of vegetables, less fat, not a lot of sweets. Do all the heart healthy things, and that will help your eyes too.”
Other risk factors include high blood pressure, heart disease and bright sunlight.
There is no proven treatment yet for the most common type of macular degeneration, called dry AMD, Garrett says.
Ten percent of people with dry AMD will progress to what’s called wet AMD, during which extra blood vessels grow under the macula, further impeding vision. Wet AMD can be treated with injections that inhibit the growth of these blood vessels, Garrett says.
Today’s takeaway: eat right and take your vitamins.