Children’s risk for myopia or nearsightedness, where objects further away look blurred because light entering the eye focuses incorrectly, may be reduced by spending more time outdoors in natural light, according to a new review of research being presented at a conference this week.
Dr Anthony Khawaja of the University of Cambridge in the UK is presenting a summary of a new analysis of evidence on natural light exposure and rising myopia rates on Tuesday at the 115th Annual Meeting of the American Academy of Ophthalmology in Orlando, Florida. Dr Justin Sherwin, also of Cambridge, led the analysis.
Khawaja said in a press statement that:
“Increasing children’s outdoor time could be a simple and cost-effective measure with important benefits for their vision and general health.”
Nearsightedness or myopia is more common today than it was 30 or 40 years ago, not only in the United States but in other countries too. For example, there are parts of Asia where 4 out of 5 people have myopia.
The new systematic review and meta-analysis, which pools data from 8 carefully selected studies, suggests that reduced time spent in natural light and/or looking at distant objects may be important factors.
The studies covered 10,400 participants altogether and looked at the links between time spent outdoors and myopia in children and adolescents.
From the pooled data, Sherwin and colleagues concluded there was a 2% drop in the risk of developing myopia for each extra hour children spent outdoors per week.
“This is equivalent to an 18% reduction for every 1 additional hour of exposure per day,” they write in the abstract presented to the meeting.
Compared to children with normal vision or who were farsighted, on average, children with myopia spent 3.7 fewer hours per week outside.
The researchers point out they can’t be sure as there is no evidence on this, but suggest the protective effect is more to do with just being outside rather than being engaged in any particular outdoor activity.
Two of the studies looked at whether the children who spent more time outside were also those less likely to be engaged with computer games, or reading or studying or doing other things that require the eyes to be focused on near objects but this was found not to be the case.
Khawaja said they would need more precise data to be more specific about what children should be doing outside.
“Future, prospective studies will help us understand which factors, such as increased use of distance vision, reduced use of near vision, natural ultra violet light exposure or physical activity, are most important,” he explained.
Khawaja also mentioned a Chinese study that was not included in Sherwin’s analysis that suggests boosting outdoor time might stop myopia in children from getting worse.
The study recruited 80 nearsighted children aged from 7 to 11 and assigned half to spend less than 30 hours on near work and more than 14 hours outdoors every week. The other half were not given any instructions (the controls).
After two years, the children who were given the instructions were less nearsighted on average than the controls.
Written by Catharine Paddock PhD