A news feature published in Nature reports on the dramatic increase in the incidence of myopia (short-sightedness) in children and adults over the past fifty years. The largest increase is in East Asia, where sixty years ago, 10-20% of the population had myopia. Today (2015), up to 90% of East Asian teens and young adults have myopia, and in Seoul, South Korea, 96.5% of 19 year-old men have myopia. The United States and Europe have seen dramatic increases in myopia, as well.
Researchers looking for the causes of this increase in myopia are currently challenging the once generally-accepted idea that short-sightedness was caused or exacerbated by prolonged reading. While genes seem to play a role in the development of myopia, another factor recently identified is insufficient exposure to bright light. Spending too much time indoors is now considered to be a risk factor for children developing myopia.
Identifying the association between myopia and less time outdoors is a recent phenomenon. It was in the early 2000s when researchers discovered that such factors as books read per week or hours spent reading or using a computer did not seem to be major contributors to myopia risk. One of the first studies to uncover an association between myopia and time outdoors was conducted by researchers at the Ohio State University College of Optometry. This study tracked more than 500 eight- and nine-year-old children who started out with healthy vision. Data collected on how the children spent their days included information about sports and other outdoor activities. After five years, one in five of the children had developed myopia, and the only environmental factor that was strongly associated with risk was time spent outdoors.
A year later, data from a study in Australia found the same association. This study followed 4000 primary and secondary students for three years. Findings indicated that children who spent less time outside were at greater risk of developing myopia.
Not all researchers are convinced that more time outside will solve the increased-myopia problem, and there are some questions about accepting more bright light as the only factor related to the prevention of myopia. Yet, there's enough support for the idea to stimulate serious thinking about how to develop initiatives to increase the amount of time children spend outside. One such idea is mandating schools to provide more outside time for children.
Research Partner