Looking for another reason to let the kids play outside?
A recent study finds that playing outside could offer a preventive measure against nearsightedness in children.
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The study looked at 6- and 7-year-old students from 12 primary schools in Guangzhou, China. Researchers found that children who had 40 minutes of outdoor activity at school had a reduced rate of nearsightedness, or myopia, over the next three years compared to those children who didn’t partake in that outdoor activity.
The findings were published in September in the Journal of the American Medical Association. They support the researchers’ theory that “near work” activities, like reading, sewing, and spending time on computers and devices, can increase myopia.
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Yet further research is needed on the possible link between myopia reduction and outdoor activity, said Dr. Michael Repka, a professor of ophthalmology and pediatrics at the Johns Hopkins University School of Medicine in Baltimore, who wrote an opinion column on the study.
Repka noted that factors such as the specific type of outdoor activity and the type of light source, which can affect eye function and development, need to be further studied. Still, he said, the study suggests another compelling reason to make sure children have some daily time outdoors.
Researchers “found a beneficial effect that wasn’t overly powerful, but at least this gives the impetus for looking for that light source, or that outdoor activity that can really play a positive role,” he told LifeZette. “It’s important to understand this is not a universal effect yet. But at least some patients did have a benefit.”
Global rates of nearsightedness have been increasing. According to the National Eye Institute, about 25 percent of Americans suffer from myopia, which makes it difficult to focus on objects that are far away. Genetics are believed to play a factor, but recent studies have started to take into account environmental factors, such as time spent outside.
Katy Bowman, a Washington-based biomechanics expert, says one important factor in spending time outdoors is the potentially beneficial effect at looking far into the distance. So incorporating time outside, which often requires your eyes to focus on objects far in the distance, is a healthy way to counterbalance long hours spent gazing at a computer screen or device.
“It’s like cross-training for your eyes,” she said. “If you think of your eye as your biceps, and you’re always looking at your machine or the four walls of your house, that’s like a range of motion in your biceps of two inches. But looking far away is like using the full range of movement, or straightening out your elbow, to keep those muscles supple and the lens of the eye always fluctuating.”
“It’s like cross-training for your eyes. Looking far away is like using the full range of movement, or straightening out your elbow, to keep those muscles supple and the lens of the eye fluctuating.”
Such muscle development could be especially important in young children, according to the Chinese research team, led by Dr. Mingguang He of the Zhongshan Ophthalmic Center in Guangzhou. He found a 9.1 percent difference in the incident rate of myopia between the children who had extra time outside and those who didn’t.
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“This is clinically important because small children who develop myopia early are most likely to progress to high myopia, which increases the risk of pathological myopia,” researchers wrote. “Thus a delay in the onset of myopia in young children, who tend to have a higher rate of progression, could provide disproportionate long-term eye health benefits.”
While Bowman said the study shouldn’t give parents any false hope that recess is a guarantee against glasses, she does note the positive effects of outdoor time for children. Her own two young children, ages 4 and 3, attend a nature preschool in which the entire curriculum is taught outside. Research-based benefits include increased immune function, vitamin D exposure and less time spent sitting, she said.
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