…according to an article at Slate. BTW, myopia is nearsightedness.
I thought spending time outdoors helped prevent myopia by using your distant vision more instead of texting to your buds on your smartphone all day long. Research suggests instead that the preventative aspect of being outdoors is related to bright light. Some quotes:
In the 1930s scientists observed that myopia was very rare in hunter-gatherer societies, and a 1960s study of native people in Alaska showed that older generations, who had not attended school, were much less likely to have myopia than younger generations, who had. Singaporean studies 20 years ago likewise linked educational attainment to myopia. If the problem is just a matter of light intensity, however, you could send your child outside to read, or purchase high-intensity light sources that mimic outdoor exposure.
According to a 2004 study from the University of Michigan, the average child in 2002 spent exactly half as much time participating in outdoor activities as did children in 1981. While myopia hasn’t yet reached the levels seen in much of Asian, prevalence in the United States is rising quickly. A 2009 study showed that the prevalence of myopia among Americans between the ages of 12 and 54 surged from 25 percent in the early 1970s to 42 percent around the turn of the millennium.