Another "Can't Miss" story about Eye Health?

Newspapers are always looking for the next great story for excitement and to garner readership. Dutifully, people quote the article as fact for a month or two, until the next ?big thing? comes out. Unfortunately, the news writers don?t dissect the scientific literature the way we do for you. A case in point is a recent study from the January 2009 issue of the usually reputable Investigative Ophthalmology & Visual Science. The February 16 issue of the Los Angeles Times cited the study from the National Runners? Health Study which ?proved? that people who run an average of 2-4 kilometers per day had a significant decrease in the risk of Age-Related Macular Degeneration when compared with those who ran less. Well, that?s certainly a ?feel good? story, isn?t it? The problem with the study, and it?s not a minor quibble, is that it fails to follow the gold standard in scientific inquiry, which includes the following three factors:

1. The study is randomized (i.e., half of the people were told to run more and half told to run less)
2. The study is prospective (starts now and then evaluates later whether an effect is seen)
3. The study is double-blind (neither the investigators or subjects know which group the subjects are in)

Number 3 would have been hard to do, because people know if they?re running or not. But the investigators didn't have to know. And points 1 and 2 were ignored completely. What you end up with is a study that proves CORRELATION, not CAUSATION. What?s the difference? Causation would have meant, in this study, that running CAUSES lower risk of macular degeneration. That?s what the authors concluded. But they were wrong. And newspapers bit into the conclusion like fish on a hook. But all that was proved was that running and lower risk of AMD were CORRELATED. In other words, healthier people are the ones more likely to run and also are the ones in a lower risk group for AMD ? similar to other diseases such as diabetes and heart diseases. It isn?t that running is helping them; it is that running and lower incidence of AMD are correlated because the people are healthier to start with! Keep your dial on this channel to learn the real news about eye health and macular degeneration. Paul Krawitz, M.D., President Vitamin Science Inc