Aspirin and Age-Related Macular Degeneration
Oct 13, 2011 - Over the past 10 years, a number of studies have explored the risk factors for developing age-related macular degeneration (AMD). Thanks to these studies, the negative impact of smoking has been established conclusively, and a great deal more has been learned about the roles of age, family history and diet on the risk of developing AMD. Learn more about AMD risk factors here.
Most of these studies also asked questions about the use of medications, such as aspirin, which are taken by many older individuals for reasons unrelated to AMD. None of them found any clear connection between aspirin use and AMD. One very large study, the US-based Women’s Health Study, even suggested that aspirin might have a beneficial effect, but these benefits were not great enough to be statistically significant.
For now, we can conclude from this body of evidence that aspirin probably does not have a big impact on the overall risk of people developing AMD. However, these studies haven’t ruled out the idea that aspirin might have an influence on how AMD develops in people at risk.
So Why AM I Reading News Headlines about Aspirin and AMD?
A study published in September, 2011, in the journal, Ophthalmology attempted to clarify the role of aspirin in AMD. However, many stories in the media have made things even more confusing. This study was led by Dr. Paulus de Jong from the Netherlands. It involved over 4600 seniors (people over age 65) from seven European countries. The researchers asked people how often they took aspirin and tested their eyes to detect signs and assess the severity of age-related macular degeneration.
This study produced two major findings:
1) Taking aspirin, no matter how frequently, was not associated with whether or not people had dry AMD.
2) Taking aspirin more frequently, however, was associated with having wet AMD.
Why would people taking aspirin frequently have higher rates of wet AMD?
There is no way to know from this study. The new study seems to have established firmly that there is an association between the use of aspirin and having AMD, but it does not prove that aspirin causes AMD.
In this study there is no information about why people are taking aspirin. Do they have headaches due to changes in their vision? Do they feel unwell? Are they taking aspirin to reduce their risk of heart disease? Understanding the reason that people are take aspirin is necessary to understand what is going on here.
The researchers that wrote the paper agree. They recognize that “there may be other confounders [i.e., unrecognized influences on the disease processes causing AMD] that were not measured.” They indicate several reasons why the results are not conclusive, and they state that further studies, which follow people over time, determine how much aspirin they use, and assess their visual function objectively, will be necessary to resolve whether aspirin influences the course and severity of AMD.
What does this mean for people with wet AMD or at risk for it?
The best advice is to talk to your eye specialist (ophthalmologist) about your specific risks.
“It is always wise to ask your doctor about any medications you are taking,” says Dr. Bill Stell, FFB Director of Research Programs. “We are prone to thinking that certain kinds of medicine are harmless: vitamins, herbal remedies and over-the-counter pain killers like aspirin. While there is no evidence in this study that aspirin causes AMD, your doctor might suggest that you avoid it. We know, for example from this study, and from others, that aspirin can increase the risk of developing intraocular hemorrhages (bleeding in the eye), which might be a reason for people with wet AMD to avoid the drug.
On the other hand, if you have been advised by your doctor to take aspirin to reduce your risk of a heart attack, do not stop taking your regular aspirin thinking that it will increase your risk of getting wet AMD. “We are still unsure about the role of aspirin in wet AMD", says Dr. Stell, “while we know that aspirin can help protect some people from heart disease."