What seems like an implausibly high figure may not be far off the mark, after all.
Reporting in the journal Lancet, the authors note that up to 90% of young adults in major East Asian countries, including China, Taiwan, Japan, Singapore and South Korea, are nearsighted. The overall rate of myopia in the U.K., by contrast, is about 20% to 30%.
At first glance, that number seems impossibly high -- almost unimaginably so. Could there have been a mistake? In China alone, 223 million people were 14 or younger in the latest census tally. If the research is right, that means over 200 million Chinese children suffer from poor vision. (Perhaps infants and preschoolers should be left out -- but then again, the official statistic also excludes students attending secondary school. The ballpark figure is shocking, either way.)
I called up Daniel Twelker, a research assistant professor in ophthalmology at the University of Arizona, to ask if there might be something skewing the results. Turns out, there's nothing skewing the results. That's right: as crazy as it sounds, those 200 million Chinese probably do have trouble seeing clearly.
"I've seen plenty of studies that show a prevalence of two-thirds of Asian school children, 70 percent, even up to three quarters," said Twelker. "I've definitely seen those reports, and they're quite believable. Anyway you cut it, it's a lot of kids that are myopic."
At the risk of being culturally insensitive, researchers have also noticed a link between myopia prevalence and nations that place a high emphasis on academic achievement. School attendance, urban living, and intelligence scores are all associated with greater rates of nearsightedness.
It also happens that what your mother told you about reading in the dark is true. For reasons researchers don't quite understand and may have to do with the vitamin D in sunlight, reading indoors in poor light raises the risk of myopia. Reading a lot -- over eight hours a day -- is also no good.
One Israeli study compared public school children with their counterparts in religious schools. Both boys and girls had roughly equal rates of myopia in public school. But the boys in religious school had much greater rates of myopia than any of their peers, said Twelker -- the result of as much as 10 hours of close reading a day. Girls in the religious schools, who weren't as burdened with what Twelker calls "near work," experienced about the same rate of myopia as those enrolled in public school.
Way to confirm all the stereotypes about nerds, scientists.