Going outside: The key to better eyesight?

Maintaining your child's vision may be as simple as making him play outside, according to a new study from the University of Cambridge. Researchers discovered that nearsighted children spent an average of 3.7 fewer hours outdoors per week than children with normal vision or who were farsighted. Is that reason enough to turn off the TV and get your kids laced up? Here, a guide to the findings:

So children who played outside more had better vision?

Yes. Compiling research from over 10,000 children and adolescents, the study found that for each additional hour children spent outdoors every week, their risk of developing nearsightedness fell by 2 percent. "Increasing children's outdoor time could be a simple and cost-effective measure with important benefits for their vision," says Dr. Anthony Khawaja, the ophthalmologist at Cambridge who presented the study.

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What causes nearsightedness?

"To be honest, we do not know," says professor Paul Foster, who supervised the research project, as quoted in Britain's Telegraph. Nearsightedness, or myopia, runs in families, but it also has been linked to external factors. Among those is the amount of time one spends focusing on near objects — when reading, for example. Studies have shown that myopia affects 42 percent of people in the United States, and more than 80 percent of people in some Asian countries.

How does being outside help kids see better?

That remains unclear. The positive effects of playing outdoors appear independent from things like time spent playing computer games or excercising. "It might be something to do with relaxing the focusing mechanism in the eye and returning it to normal distance vision," Foster says. Or it could be the increased exposure to ultraviolet light, which helps control the length of the eye and could help curb myopia. It will take more research to pinpoint what's happening and translate it into recommendations for parents.

Sources: Live Science, Telegraph, CBS News