Simply letting your children run around outdoors can greatly reduce the chance they will become short-sighted, new research suggests.
A review of eight studies by Cambridge University, involving 10,400 participants, concluded that every hour spent outside can reduce the risk of a child becoming near-sighted by up to two per cent, reports the UK’s Daily Telegraph.
The study linked the amount of hours a child spends outside with incidences of near-sightedness (or myopia) and also found short-sighted children spend approximately 3.7 hours less a week outside than children with normal or long-sighted vision.
The link was made between myopia, which runs in families, and indoor activities like reading, spending time on the computer and other activities requiring focus on near objects for long periods of time.
The scientists who conducted the research, Dr Justin Sherwin and Dr Anthony Khawaja, presented their findings to the American Academy of Opthalmology this week, and suggested that increased exposure to ultraviolet light from being outdoors could be the key beneficial factor.
Dr Sherwin explained that myopia occurs when the physical length of the eye is greater than the optical length. Studies have shown that UV rays may have an impact on chemicals affecting the rate of physical growth, and that a lack of sunlight could cause the eye to grow too much.
“It could be caused by not enough UV radiation, but it could also be spending less time looking into the distance or not enough physical activity,” he said.
Myopia affects approximately one in five people in Australia, with figures significantly higher in other countries around the world, including as high as one in two in some Asian countries.
A comparison study of children living in Australia and those in China and Singapore (which has the highest rate of myopia globally) found that participants in Australia had better vision overall than their counterparts, with the discerning factor being a greater tendency to spend time outdoors.
“To be honest we do not know what causes people to become short-sighted, but they tend to read a lot more and to have higher academic achievement and we tend to assume it is because they are reading all the time,” said Professor Paul Foster who supervised the Cambridge project.
He added: “It might be something to do with relaxing the focusing mechanism in the eye and returning it to normal distance vision, and the wavelengths of light we are exposed to outside could also have an impact.”