Sending your children outside to play can not only boost their physical fitness – it may also cut the risk of becoming near sighted. Nearsightedness, also known as myopia, has become much more common in many countries over the past four decades, including Canada and the United States. In parts of Asia, more than 80 percent of the population is nearsighted. A new analysis of recent eye health studies by researchers from the University of Cambridge, England showed that increased time spent outdoors is related to reduced rates of nearsightedness in children and adolescents. The analysis was led by Dr. Justin Sherwin and presented by Dr. Anthony Khawaja at the recent 115th Annual Meeting of the American Academy of Ophthalmology in Orlando, Florida.
The analysis suggests that more exposure to natural light and/or time spent looking at distant objects may be key factors. The data included in the analysis was drawn from eight carefully selected studies that focused on myopia in children and adolescents and how long they spend outdoors. The studies involved a total of 10,400 individuals. Dr. Sherwin’s team concluded that for each additional hour spent outdoors per week, the chance of myopia dropped by approximately two percent. Nearsighted children spent on average 3.7 fewer hours per week outdoors than those who either had normal vision or were farsighted (also known as hyperopia)
Though the reasons aren’t yet clear, the protective effect appears to result from simply being outdoors rather than performing a specific activity. Two of the eight studies they analyzed tried to determine whether children who spent more time outdoors were also those who spent less time performing near work, such as playing computer games or studying, but no such relationship was found in either study. The amount of time spent on near work is of interest to researchers as another potential cause for the recent rise in nearsightedness.
“Increasing children’s outdoor time could be a simple and cost-effective measure with important benefits for their vision and general health” said Dr. Khawaja. “If we want to make clear recommendations, however, we’ll need more precise data. 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.”
Another question Dr. Khawaja considered is whether nearsighted children might benefit from extra hours outdoors as well by preventing their myopia from becoming more severe. He cited a recent Chinese study, not included in Dr. Sherwin’s analysis, of 80 nearsighted children between the ages of 7 and 11. Forty of them were assigned to spend less than 30 hours on near work and more than 14 hours on outdoor time per week. At the end of the two-year study, children in the intervention group were less nearsighted on average than the 40 control group children who did not follow the special schedule.
SOURCE: American Academy of Ophthalmology, news release, Oct. 21, 2011