The studies tracked approximately 41,000 runners for more than seven years, and found that running reduced the risk of both cataracts and age-related macular degeneration.

The research, conducted by the US Department of Energy's Lawrence Berkeley National Laboratory, is among the first to suggest that vigorous exercise may help prevent vision loss and offers hope for people seeking to fend off the onset of eye disease.

"In addition to obtaining regular eye exams, people can take a more active role in preserving their vision," says Paul Williams, an epidemiologist at Berkeley Lab's Life Sciences Division who conducted the research.

"The studies suggest that people can perhaps lessen their risk for these diseases by taking part in a fitness regimen that includes vigorous exercise."