A recent research study is getting a lot of attention because it showed a statistical link between daily aspirin use and wet macular degeneration.  As usual with these news stories, it's important to look deeper than the headline.  One irresponsible headline actually stated, "Aspirin Causes Blindness" - which is definitely untrue.

Remember that many seniors take a daily aspirin for their circulation and heart health - often prescribed by their cardiologists or other doctors.  For this purpose, aspirin is taken because it is a blood thinner. A person with wet macular degeneration develops blood vessels in the eye that break, leak and bleed.  Certainly, a person taking aspirin may have thinner blood, which means that any leak may bleed more than in a person with thicker blood.  The aspirin didn't cause the macular degeneration and didn't cause the leak.

The study used a questionnaire with about 4,700 people over age 65 years. They were asked about aspirin use and also about other factors, such as medical history, socioeconomic background, smoking and alcohol consumption.  The participants then had a routine dilated eye examination and where AMD was found, it was classified by severity on a scale that is standard in ophthalmology.

On the surface, the statistics showed that people with daily aspirin use were twice as likely to have developed wet macular degeneration.   The study did take into account those other factors from the questionnaire in coming up with these numbers.

One of the important issues with this research is that some of those factors, like cardiovascular disease and smoking, are themselves risk factors for macular degeneration.

The study could show an association between daily aspirin use and wet AMD, but not a causative effect.

October 2011