Play Outside to Protect Kids Eyes
In the 1960’s, a dramatic increase in nearsightedness, or myopia, was noticed in an Inuit community in northern Alaska. While virtually none of the parents or grandparents in the community had vision loss, approximately 58% of their children needed glasses. A 1969 study noted that, with the introduction of American education requirements to the region, the children were spending their days in school, while their parents had not. The authors hypothesized that this environmental change may have led to decreased vision in the children.
During the half century since that study, nearsightedness has been spreading dramatically across the world. In Europe and the U.S., the prevalence has doubled, and now affects about half of young adults. In Asia, meanwhile, the rate has skyrocketed. Up to 90% of teens and young adults are near-sighted in China, while in Seoul the prevalence is over 95% of in some groups.
What is the cause of this increase?
For years, we have learned that too much time staring at books and screens hurts kids’ eyes. Parents today warn their children not to stare too long at screens, and our parents told us not to watch too much TV. It now appears, however, not to be the books or screens that cause the problem. It is being indoors.
Starting in the 2000’s, researchers started looking at children with normal vision and following them over time for the development of myopia. A study in California found, almost accidentally, that kids who spent more time outside had a lower risk. Another study in Australia found the same result.
Studies were then done on children in China and Taiwan. Groups of children were assigned to outdoor classes or mandatory outdoor recess and compared to children who spent these time periods indoors over the course of one to three years. In both studies, kids who were outside more had a lower chance of developing nearsightedness. The more time outside the better the protection.
In these studies, it didn’t matter if the kids were playing sports or reading books in an outdoor class under a tree. As long as they were outside, they were protected.
How does being outdoors protect eyes?
The light that we experience outside is generally much more intense than the light we experience indoors. Light intensity can be measured in “lux”. Generally, indoor classrooms and offices provide about 500 lux, while sitting outdoors provides closer to 10,000 lux.
It is thought that the higher light intensity is needed to stimulate normal eye development in childhood. Lower intensity light disrupts healthy eye growth and leads to decreased vision in adulthood. It is thought that about 3 hours of time outdoors is needed to protect the eyes.
“Go outside and play!”
Time outside is good for kids’ hearts, muscles, minds, and, it turns out, their eyes. Parents in 2017 have yet another reason to continue the age-old mantra to our children- “Go outside and play”!
“The myopia boom- Short-sightedness is reaching epidemic proportions. Some scientists think they have found a reason why”. Nature, News Feature. Elie Dolgin, 18 March 2015