PARENTS are being urged to ensure their children spend at least two hours outside each day to reduce the risk of developing short-sightedness.

A study of 101 children between the ages of 10 and 15 by researchers at Queensland University of Technology found increased exposure to outdoor light stopped myopia progressing.

Myopia occurs when a child’s eyes grow too rapidly, but the study, completed over a period of 18 months, found outdoor light slowed the growth.

QUT Associate professor and study co-author Scott Read said about 20 per cent of Australian children had myopia. But about 80 per cent of Chinese children were short sighted.

“The activities of children are different in other countries. In places like China they have a very high prevalence of myopia and it’s likely their lifestyles are different,” he said.

QUT professor Michael Collins, who worked on the research with Dr Read, said glass ceilings were being tried in school classrooms in China.

“[Glass ceilings] would probably help, although it’s 200 times brighter outside than inside a classroom and it’s difficult to replicate that,” he said.

“In China, kids are encouraged to spend a class period outdoors at the end of the day to get more sunlight.”

Associate professor Read said he hoped optometrists would tell parents about the findings and encourage them to ensure their children spent time outdoors.

“Obviously kids get a reasonable amount of their outdoor time during the school day, so I think schools and parents can play a part in helping to increase the amount of time outside,” he said.

Associate professor Read said less than an hour of bright light each day would put kids at risk of developing myopia.

“Results show the children who had the lowest daily light exposure showed the fastest rate of eye growth,” he said.

“Around two hours per day exposed to bright light is probably the important factor.”

Nature Play WA chief executive Griffin Longley, whose group aims to increase the time WA children spend outdoors, said the research made it even more important for children to spend time outside.

“It is positive in that it really adds to the case for the need to get kids out,” he said.

“It’s negative in that it shows one more negative impact of modern childhoods.”

Mr Longley said modern parenting was difficult because children were surrounded by technology and parents faced longer working hours.

“Parents will want to take their kids outside more, but their ability to make those changes won’t be changed,” he said.

“Fourteen per cent of kids have mental health disorders, 24 per cent are overweight or obese and the growing myopia issue is all adding up to harder times with families.”

Associate professor Read said the study was small in scale and future studies needed to look at a broader population.

“Future research probably needs to look at large populations and what particular factors of light affects the vision, like time of day or wave length,” he said.