Update, April 2009: In hindsight, I didn’t cover this subject thoroughly enough here, leaving some questions unanswered. For a more comprehensive overview, see this article I wrote for the Korea Times.
Update 2, June 2013: And for a much more up-to-date overview, see this article I wrote for Busan Haps.
If I’d been asked this question yesterday, then I too would have answered that it was because they were always hunched over their books, or staring at computer screens. But the surprising result of this Australian study was that those are only correlated but not causative factors.
In fact, it’s because they don’t get enough exposure to sunlight.
I confess, before I read the details of the survey, I was very sympathetic to such a result: young Korean women, for instance, have among the lowest Vitamin D levels in the world because of avoiding the sun for the sake of light skins, and given how the required behavior and body images that lead to such extremes are inculcated very early in Korean children’s lives, then if a lack of sunlight does indeed lead to myopia (short-sightedness) I’d wager money on rates being higher among Korean teenage girls than boys. Not much higher, no, but I’d still expect a statistically significant difference between them.
But technically the study never looked at Korean children specifically. And while Korea certainly shares other developed East Asian countries’ skyrocketing rates of myopia among children — virtually all my middle-school students wear glasses or contact lenses, and I bet yours do too — I was confused when I heard that the study was primarily based on Singaporean children.
How on Earth do children that live on the equator not get enough sun?
Actually, partially it’s precisely because they live there. As head researcher Dr. Ian Morgan explains in an Australian radio interview, the heat meant that:
The children in Singapore were spending about three hours a week outside, so very, very limited periods of time outside, excluding the school hours. Basically they went to school, they went home, they did their homework and then they watched television and that was life.
But this issue of climate wouldn’t apply so much to children in other East Asian countries, where the same education culture of going to school during the day and then cram schools in the evenings prevails, although that does also mean that they’re not outdoors much of course. But how to tease apart the effects of that lifestyle from a lack of sunlight specifically? Things like diet, and, say, the not insignificant fact that Korean children get the least sleep in the world, would presumably have some effect too.
Here’s the key part of the radio interview that reveals how and why researchers did that. Without it, basic summaries of the study like this and this that are all over the news wires are good introductions, but raise more questions than answers really:
DR IAN MORGAN:….we have been able to compare the prevalence of myopia in Chinese kids in Singapore, as compared to kids of Chinese origin growing up in Sydney. And at the age of six, the kids in Singapore — the Chinese kids in Singapore are ten times more myopic than the kids of Chinese origin in Australia.
INTERVIWER: But did the Singaporean children spend more time in near-work activity than the Sydney children?
DR IAN MORGAN: If anything, they spent a little bit less and this is what led in part to us looking for what other factors could be important. And the striking difference that came across was that these kids — remember they’re matched for age and they’re matched for ethnicity, they’re all of Chinese origin. The kids of Chinese origin in Sydney were spending a lot more time outdoors than the kids of Chinese origin in Singapore.
For more details, including the debunking of alternative theories that there is some genetic susceptibility to myopia among East Asian populations, and why it is specifically light intensity that is important, then I highly recommend reading the radio interview in full.
I don’t have the time to translate anything myself unfortunately, but it’ll be interesting to see how the Korea media interprets the results of this study. While it would be just one of a very long list of serious social and health problems among young Koreans resulting from Korea’s after-school institute or hagwon (학원) culture, and so unlikely to lead to any huge changes overnight, all the various English-language articles on the study point out that governments across the region already do have serious concerns about the issue. So, this may well provide just enough of a shove for Korean schools to, say, provide more outdoor physical education and field trips for students. Granted that it’s rather cold at the moment though!