By Sharon Oosthoek

Go outside and play. It’s a rare child who hasn’t heard those words, and now there’s another reason to heed them – better eyesight. Australian and Singaporean researchers have found that the more time kids spend outdoors, the less likely they are to be nearsighted.

From 2003 to 2005, researchers at the University of Sydney in Australia gave eye exams to more than 2,000 12-year-olds and then asked them and their parents how much time they spent outside.

The average was 2.39 hours a day, but the children who exceeded the average were less likely to be myopic than those who did not, regardless of confounding factors such as their parents’ myopia. Researchers at the National University of Singapore, who conducted a similar study of more than 1,200 teens in 2006, came to the same conclusion.

So what’s going on? Do kids who spend more time outside spend less time straining their eyes reading or playing video games? No, say researchers. “Close work” had little effect on eyesight.

Light may be the answer. According to the Australian researchers, “Light intensities are typically higher outdoors than indoors, and pupils will be more constricted outdoors. This would result in a greater depth of field and less image blur.”

The findings come at a time when myopia among children appears to be on the rise: in the West, one in three children is nearsighted, and in some highly urbanized East Asian regions the incidence of myopia exceeds 80 percent.