A pain-reliever known for its life-saving potential in the event of a heart attack might also be linked with age-related vision loss when taken regularly, according to a new study in the journal JAMA Internal Medicine.
The findings show an association between regularly taking aspirin and an increased risk of developing the more severe "wet" form of age-related macular degeneration -- even when smoking and heart disease risks are taken into account. And the researchers found that the relationship was "dose-dependent" -- meaning, the more aspirin a person took regularly, the higher the risk of the vision loss condition.
Age-related macular degeneration, which is the leading cause of blindness among people over the age of 55, is a vision loss condition that occurs with the degeneration of the retina, according to the American Macular Degeneration Foundation. It is marked by loss of sight in the center of the field of vision, and is separated into two main types of macular degeneration: Dry, which is more common, and wet, which is rarer but more severe, the Mayo Clinic reported. Wet age-related macular degeneration occurs when blood vessels leak into the macula (which is located in the middle of the retina), thereby blocking vision.
The new study, conducted by University of Sydney researchers, included 2,389 people whose aspirin habits and vision loss were tracked over 15 years (via four examinations). Of those people, 257 (or 10.8 percent) regularly took aspirin; however, researchers didn't have full information on why these people took the aspirin, MedPage Today noted.
By the end of the study period, 24.5 percent of the study participants had developed "wet," or neovascular, age-related macular degeneration. But researchers found that a greater proportion of regular aspirin users had the disease as they followed up throughout the years than the aspirin non-users.
For example, at the five-year mark, 0.8 percent of people who didn't regularly take aspirin had "wet" age-related macular degeneration, compared with 1.9 percent of people who did regularly take aspirin. Incidence was 1.6 percent among non-users at 10 years, compared with 7 percent among users. And incidence was 3.7 percent among non-users at 15 years, compared with 9.3 percent among users.
However, researchers noted that the evidence is still not strong enough to suggest people altogether stop regular aspirin use, though some who may be at an increased risk for age-related macular degeneration might want to talk to their doctors about their risks.
In a related commentary, experts at Cedars-Sinai Medical Center concurred that the new findings, while interesting, shouldn't change clinical practice just yet. "From a purely science-of-medicine perspective, the strength of evidence is not sufficiently robust to be clinically directive," they wrote. "These findings are, at best, hypothesis-generating that should await validation in prospective randomized studies before guiding clinical practice or patient behavior."
Past studies have also shown associations between increased age-related macular degeneration risk and aspirin use. A study published last year in the Journal of the American Medical Association showed that regularly taking aspirin for a decade is linked with an increased risk of developing the eye disease. However, outside experts were also surprised by the findings of that study, Everyday Health reported.
"Many retina doctors did not believe this was true because they have never seen anything like it in their practice. Not only that, there is no obvious mechanism for how aspirin would affect AMD," Dr. Robert Cykiert, M.D., who is in the Department of Ophthalmology at New York University, told Everyday Health. "Unless there’s something hidden about AMD that we don't understand yet, there doesn't seem to be a logical explanation for it, so we tend to doubt it before we have more evidence."
Another study, published in 2011 in the journal Ophthalmology, showed that people who take aspirin twice a day have a doubled risk of advanced age-related macular degeneration, compared with people who don't regularly take aspirin. However, the risk is still relatively low.