New research by the University of Sydney has revealed that environmental factors like close-reading and intensive study can lead to short-sightedness, or myopia, but playing outdoors can help protect children from this effect.
The sunlight is believed to cut myopia by encouraging the release of a brain chemical which stops excessive eye growth.
Dr Kathryn Rose, from the university's faculty of health sciences, said the results were in line with an American study which found that outdoor sport was protective.
"However, our study shows that the crucial feature is being outdoors irrespective of the activity you are doing," Dr Rose said.
The team gave comprehensive eye examination to 4,000 Year 1 and 7 Sydney students from 55 schools.
"Our results show that the protective effect of time spent outdoors persists even if a child is doing a lot of near work such as reading and studying," Dr Rose said.
Interestingly, the researchers found that television watching and using computers appeared to have little effect on the development of short-sightedness.
Researchers are still unclear exactly how the outdoors protects the eyes but they believe exposure to sunlight fosters the release of dopamine which is known to slow eye growth. Myopia is caused by excessive eye growth.
Rates of the condition have increased from 15 per cent to 20 to 25 per cent in the past 30 years.
Professor Paul Mitchell of the Centre for Vision Research and Westmead Millennium Institute, who was also involved in the study, said the results should be used to inform public health policy.
"Promoting outdoor activity to parents and families, and including more outdoor pursuits in school curricula, could be an important public health measure to avoid the development of myopia," Prof Mitchell said.
"This public health message would be particularly relevant in those countries where the rates of myopia in children are very high, such as in Singapore and Taiwan."
