The rise of myopia, also known as shortsightedness, has increased significantly in the past 30 years in the United States. Time spent outdoors has dropped off in this time period. Researchers at the National Eye Institute conducted a study of children and teens that shows a possible link between less time spent in outdoor activity and myopia.
In the early 1970’s, 25% of 12 to 54 year olds in the United States had myopia. In 1999-2004, that figure was 42%, a huge increase.
Myopia means that the eye focuses in front of the retina, making vision blurry. This condition is thought to be caused by a combination of genetics and environmental factors. However, genetics cannot explain such a rapid increase. Therefore, behavior or environment must have changed.
The study looked at 8 studies of a total of 10,400 children and teens. The researchers found that for each added hour spent outside in a week, the chance of myopia appeared to decrease by 2%. Children who were nearsighted spent an average of 3.7 fewer hours outdoors per week, compared to children with farsighted or normal sight.
It is not exactly clear what was preventing myopia in children who spent more time outdoors. While outdoors, people look out in the distance more frequently, which exercises the eye muscles. They look close up less frequently. The eyes are exposed to natural UV light outside. Children naturally engage in physical activity while outdoors. Any of these factors could explain the reduced myopia, and it could be a combination of factors.
Getting plenty of outdoor exercise has a long list of documented health benefits. If further research concludes the researcher’s findings, reduced myopia may be added to this list. This may be another example of natural self-care preventing eye problems before they start.
Source: Paper presented at the American Academy of Ophthalmology Annual Meeting October 2011 “Is Outdoor Activity Protective Against Myopia in Children and Young Adults? A Systematic Review and Meta-analytsis by A.P. Khawja et.al.