科学美国人60秒:Vision Needed to Curb Nearsightedness Epidemic

“So we’re inside, we’re in fake lighting, we’re not spending as much time outside in the context in which our visual system evolved.”

Amanda Melin, assistant professor of anthropology & archaeology and of medical genetics at the University of Calgary. And all that sitting inside in dim light staring at screens has led to an epidemic of myopia—nearsightedness—among young people.

“The myopia epidemic is particularly strong in Asia and in urban Asian environments, where it is increasing to be upwards of 90 percent of teenagers are myopes.”

Melin spoke February 20th at a press briefing at the annual meeting of the American Association for the Advancement of Science in Boston.

“So to be sure there’s a genetic component, my father had glasses I have glasses. But we’re increasingly realizing that the environments in which we’re spending our time are playing a major role.

“And so a cohort study where some school age children were given 40 minutes or more time outside, those children had a 23 to 50 percent less likely chance of developing myopia than students at schools who were not given that same amount of outdoor exposure. And it looks to be dosage dependent, so the longer time you spend outside the less chance you have of developing myopia.

“So the exact mechanisms are not really known, so we really need a lot more research into this. But another major factor that’s being implicated is near-work activities, so spending our time looking at computers, into microscopes, these things. And then as soon as we leave our work, what are we doing, we’re on our mobile devices, that’s also a very close activity.

“When we’re engaged in near-focus tasks our eyes are actually working really hard, because the muscles have to accommodate the lens to focus that close. When we look off into a distance that’s when our eyes are relaxing, so there could be something with that as well.

“When you’re outside, the ambient light is…orders of magnitude brighter outside in outdoor lighting environments, so that probably has a very important role…we need to think about perhaps policies in place to get kids and young adults outside a bit more.”

—Steve Mirsky