Outdoor play can save kids' eyesight
Updated
Researchers in Australia have discovered that playing outdoors can help protect children from becoming short-sighted. The study was done by the Australia Research Council's Centre of Excellence in Vision Science; its scientists compared ethnic Chinese Australian children with children in Singapore. Nearly a third of Singaporean six-year-olds need glasses; but they're worn by just three percent of ethnic Chinese children living in Australia. The lead researcher, Professor Ian Morgan, says that while genetic inheritance causes some children to develop short-sight, in most cases the real problem lies in spending too much time studying and reading indoors, and not enough time outside playing.
Presenter: Corinne Podger
Speaker: Professor Ian Morgan, from the Australian Centre of Excellence in Vision Science at the Australian National University
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MORGAN: Well I can tell you the prevalence found is first of all six year old children of Chinese origin in Singapore, about 30 per cent are short-sighted already. In Sydney comparable children of Chinese origin about three per cent, so a huge difference. And the only factor that differed the could explain that magnitude of difference was the time they spent outside. Kids of Chinese origin in Sydney outside for about two hours a day in addition to school hours, kids of Chinese origin in Singapore about half an hour a day.
PODGER: Were you able to determine an optimum amount of time that children should spend outdoors to give them maximum protection for their eyesight?
MORGAN: No we don't have a tight figure on that yet, certainly you have to take into account school hours. And it looks as though if children are getting outside in addition to their school hours by about three hours then you can protect them from the effects of, in a sense, too much study, and you can also protect them from the fact that their parents are short-sighted.
PODGER: Now watching tv, reading and playing video games, they've all been blamed for damaging children's eyesight. Did you find evidence to support that in your study?
MORGAN: No, those activities seem to be pretty neutral at least in terms of myopia. They could however have a negative effect if they stopped children getting outside. So if the patten a child adopts is to go to school, come home, do their homework and then watch television that's a bad pattern. But it's not the television itself, it's preventing the kids getting outside that seems to be the problem.
PODGER: And being outside is it a case of natural light or is it the opportunity to focus on different things at different distances?
MORGAN: Well we have a hypothesis, that's one we have to prove, but our hypothesis is that it's the brightness of the light. There's a big difference between light intensity inside, which tends to be quite low and light intensity outside. There is evidence that bright light will induce release of a transmitter called dopamine from the retina and that blocks the growth of the eye, which is just what we want to do when somebody's becoming myopic.
PODGER: Now people from Asian backgrounds are known to suffer short-sightedness more commonly than Europeans. Would your findings apply equally to children from other ethnic backgrounds?
MORGAN: Yes indeed well we've quoted the evidence on the comparison of children of Chinese origin in Singapore and in Sydney, but it applies to the whole population in Sydney. We see the same effect in the kids of European origin, and there's some confirmatory results coming from the United States as well. So it seems to be a pretty general finding. And what it points to is this perception, which is a real perception that Chinese children tend to have glasses more often than kids of European origin. It's probably not anything to do with the genetics of being Chinese, it's once again that particular pattern of intensive study coupled with not enough time outside that explains the difference.
PODGER: But obviously genetics does have something to do with being short-sighted?
MORGAN: There clearly are genetic cases of myopia. They tend to be myopia which develops very young in life and becomes quite severe by the end of childhood. But that only accounts for about one to two per cent of the population. Most of the myopia that's occurred in East Asia is a result of environmental exposures, intensive study and not enough time outside.
