A lack of exposure to sunlight, rather than too much time spent in front of the television or playing computer games, has been found to damage childre

Spending time in sun can prevent children becoming short-sighted
article in the Telegraph

Extract:

"The study, carried out by researchers from the Australian National University and Sydney University, compared the eyesight of young Chinese Australians and Singaporeans. It found that 30 per cent of six-year-olds in Singapore need glasses, compared with 3 per cent of Chinese Australians.

Both groups spend the same amount of time playing video games, reading and watching television, but children in Singapore spend an average of 30 minutes each day outside, compared with two hours in Australia.

The figures were similar when contrasting children of Chinese descent from both nations, allowing researchers to eliminate ethnicity as a factor.

Short-sightedness is traditionally a problem among the highly educated who spend a lot of time indoors, lead researcher Professor Ian Morgan said.

"There's a driver for people to become myopic and that's education," he said. "And there's a brake on people becoming myopic and that's people going outside."

Mr Morgan said the research found playing video games had the same effect on vision as reading, using the computer had a "neutral" effect, and watching television had no affect at all."