Nature magazine considers the growing evidence.

Evidence continues to mount that spending too long indoors is placing children at risk of developing myopia, according to an article in Nature magazine on what it calls the “Myopia Boom.” The condition now affects around half of young adults in the United States and Europe — “double the prevalence of half a century ago,” says the report. “By some estimates, one-third of the world's population — 2.5 billion people — could be affected by short-sightedness by the end of this decade. “We are going down the path of having a myopia epidemic,” says one vision scientist. Says another: “We're really trying to give this message now that children need to spend more time outside.”

Read more and see images at Nature