Many people take aspirin to prevent heart attacks, but new research suggests the added benefits may be coming at the expense of pill-takers' eyesight.
A 15-year-study published Jan. 22 in JAMA Internal Medicine showed that people taking regular aspirin faced a higher risk for age-related macular degeneration (AMD), one of the leading causes of blindness in older adults. The research also suggests the risk may worsen over time.
AMD commonly affects adults 50 and older, gradually destroying their "macula," which is a part of the eye that provides sharp, central vision that's required to see objects clearly. There are two types of the disease: "Dry" AMD is most common and occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision while "wet" or neovascular AMD occurs when blood vessels under the macula leak blood and fluid, causing damage. Wet AMD is often more severe but also more rare, affecting about 10 percent of patients with AMD.
People at a high risk for having a heart attack -- such as those who have heart disease -- are encouraged by the American Heart Association and other medical groups to take a daily low-dose of aspirin.
For the study, Australian researchers tracked nearly 2,400 adults who were given four exams during the 15 year study. More than 250 of these individuals took aspirin regularly because aspirin is thought to prevent clots from forming by "thinning" the blood.
The researchers found an increased risk for wet AMD among aspirin takers, with 1.9 percent of patients having the condition at five years, 7 percent at 10 years and 9.3 percent at 15 years. That compares with 0.8 percent of non-aspirin takers at five years, 1.6 percent at 10 years and 3.7 percent at 15 years.
"Regular aspirin use was significantly associated with an increased incidence of neovascular AMD," concluded the authors, led by Dr. Gerald Liew of the University of Sydney in Australia.
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Should all people taking aspirin be worried?
Liew wrote that the decision to stop taking aspirin is a "complex" one and should be decided on an individual basis. For example, those at a higher risk for AMD such as people with a family history or smokers -- who are two times more likely to develop AMD than non-smokers -- may want to consider changing their aspirin regimen.
In an accompanying editorial published in the same issue, Dr. Sanjay Kaul and Dr. George A. Diamond, cardiologists at Cedars-Sinai Medical Center, Los Angeles, wrote that the study was observational, and could not prove cause and effect. Therefore, it may be too soon to recommend people curb their aspirin intake.
"In the absence of definitive evidence regarding whether limiting aspirin exposure mitigates AMD risk, one obvious course of action is to maintain the status quo," they wrote.
Dr. Gregg Fonarow, a spokesman for the American Heart Association and professor of cardiology at the University of California, Los Angeles, added to HealthDay that more rigorous randomized controlled trials have yet to demonstrate any increased risk of blindness from people taking aspirin.
"Individuals prescribed aspirin for high-risk primary prevention or secondary cardiovascular prevention should not be concerned or discontinue this beneficial therapy," he said.
To reduce your risk for AMD, the National Eye Institute recommends exercising, eating a healthy diet rich in leafy greens and fish, maintaining normal blood pressure and cholesterol, and avoiding smoking.