When you say to your kids, "Hey, let’s turn of the tv and go outside and run around a bit," you’re probably thinking about a few immediately obvious benefits from exercising:
Fresh air, activity that strengthens muscles, lungs and heart. A change in the mood from couch potato inertia to active engagement.
But did you think about vision health?
Well, two studies in the last two years have demonstrated quite clearly that kids who spend more time outdoors have less of a risk of developing nearsightedness or myopia. The rates of myopia among children is growing worldwide which has led researchers to believe that environmental factors play as much a role as genetic factors.
The first study, published in the journal Opthamology in 2008, was conducted in Australia and involved nearly 4000 school children. It surveyed parents of children ages 6 to 12 about the level of outdoor vs. indoor activity and also how much near work (like reading and writing) they did. At age 12, the children were tested for myopic refractive error.
The study found that the children with the worst levels of myopic refractive error did the most near work and the least amount of outdoor activity. Interestingly enough, the children who had the most outdoor time – independent of how much near work they did – had the lowest levels of myopia.
And just as important to note, the kids who played lots of sports indoors showed no improvement. It was the time spent outdoors that was the deciding factor.
The second study was conducted at the New England College of Optometry. In this study researchers handed out surveys to parents of 191 children with an average age of 13. The surveys documented how much time kids spent doing activities like watching tv, reading and outdoors. Each child had an annual eye exam.
The study found that the kids with myopia spent the least amount of time outdoors (8 hours/week vs. the 13 hours/week of the other children). These children also spent more time watching tv (12 hours vs. 8 hours/week).
Researchers from both these studies are still trying to pinpoint what exactly makes the difference. But they have a couple of compelling theories:
- Outdoors, you get more chances to look long distance. Animal studies have clearly demonstrated that animals deprived of long distance vistas tend to develop nearsightedness and that myopia can be prevented by providing opportunities to look into the distance.
- Outdoor light intensity causes the pupil to constrict allowing for a larger depth of focus. The range in which objects appear clear is greater and there’s less blurring of images.
- Myopic eyes are longer from front to back than normal eyes. In response to intense light, the retina of the eye releases the neurotransmitter dopamine which inhibits growth. This may mean that the higher intensity light of outdoors actually inhibits the growth of the eye and minimizes the chance of myopia.
Good vision is just one of hundreds of good reasons to go outdoors. While the studies note that sports is not necessarily a requirement for the vision benefits of outdoors, why not add the activity in to the mix. And if you’ve got a choice to play indoors vs. outdoors, head outdoors for sharper vision.