Exercise for your eyes

We all know that exercise makes for a stronger heart and reduces the risk of heart disease, diabetes and a number of other conditions. But now there’s more to add to the list: Vigorous exercise also may help prevent age-related macular degeneration and cataracts, both of which can affect vision.

Two new studies looked at data from almost eight years of follow-up from the National Runners’ Health Study. In one, 110 men and 42 women received a clinical diagnosis of age-related macular degeneration during the follow-up. The more the runners ran, the less risk they had for developing age-related macular degeneration. Running an average of two to four kilometers a day reduced the risk by 19 percent, and running more than four kilometers per day reduced the risk by 42 percent to 54 percent, compared with those who ran less than two kilometers a day. Running an extra kilometer per day was associated with a 10 percent decrease in relative risk. Numbers were adjusted for age, sex, diet and smoking history.

Another study examined the effects of running on developing cataracts. Among the same group of runners, 733 men and 179 women reported having cataracts during the follow-up. Men who ran had a lower risk of cataracts, even after adjusting for body mass index. Those who ran 64 or more kilometers a week had a 35 percent lower cataract risk than those who ran less than 16 kilometers per week. And those with better cardiovascular fitness were also at less risk than men who were less fit.

Although it’s not fully known why a link exists between fitness and preventing these conditions, study author Paul T. Williams, a staff scientist with the Department of Energy’s Lawrence Berkeley National Laboratory, believes that exercise could provide similar protective benefits for the eyes as it does for the heart and other systems.

“There are overlaps,” he says. Higher levels of HDL (good) cholesterol are associated with a lower risk of age-related macular degeneration. Also, C-reactive protein, which shows higher levels during inflammation, may contribute to cataracts. Exercise typically boosts levels of HDL cholesterol and lowers levels of C-reactive protein.

The study appeared in the January issue of Investigative Ophthamology & Visual Science.