Myopia in East Asia

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[The following is a guest post by Dr. Ian Morgan of the Research School of Biology, Australian National University, Canberra, Australia and Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.  It is in response to "Chinese characters and eyesight" (11/12/14), which generated a lot of interest and discussion, and which references the work and views of Dr. Morgan.]

I came across your blog and the comments on the relationship between Chinese characters and myopia quite recently, and I thought it was worth a quick response.

First, I should dispose of one issue – that of genetics. The best available evidence is that at most 1% of the population becomes myopic for genetic reasons. The high prevalence of myopia seen in much of East and Southeast Asia is primarily due to environmental exposures – in particular too much near work and too little time outdoors.

As far as I can see, there is no direct relationship between Chinese characters and myopia. As some of the comments pointed out, the prevalence of myopia is now high in countries which do not use Chinese characters routinely such as South Korea, which seems to currently hold the world record for myopia. Perhaps the most telling case is Singapore, in which Indians and Malays are almost as myopic as the Chinese, without any study of Chinese characters. The slight differences which exist could be genetic, but they correlate with lower levels of educational success and more time spent outdoors. The prevalence of myopia is now increasing in many countries, including the United States and Germany.

One of the comments also pointed to the high prevalence of myopia reported in Orthodox Jewish males, who rarely read Chinese. It is striking that girls, whether they attended secular or Orthodox schools, were not particularly myopic, and nor were boys who did not attend Orthodox schools. The authors argued convincingly that the cause was the intense study demands on Orthodox Jewish boys (which was probably associated with too little time outdoors in my view).

All this suggests to me that the problem is not with the characters per se. What a lot of data shows is that children in East Asia spend very little time outdoors, particularly in their early years, and do much more study than is common in western countries. However, the question of why this cultural pattern has emerged is certainly worth thinking about.

Here I have just a series of questions. Is it simply that the study demands of learning the characters are so high that adoption of a life-style of too much study and too little time outdoors was inevitable for those who wished to become literate? When literacy is required for the whole Chinese population, does this inevitably mean an epidemic of myopia? Was this Chinese practice then adopted by other countries such as Korea because of the prestige of Chinese culture? Was this tendency reinforced by the keju (gaokao) system in which one examination determined your social place for life? Are the highly competitive education systems typical of all the countries in East and Southeast Asia which have developed epidemics of myopia simply an extension to the whole population of what began as an elite educational stream?

Coming back to the question of nearwork and time outdoors, the question for China is whether children can get enough time outdoors to prevent them developing myopia (2-3 hours a day seems pretty powerful), and at the same time become literate. Or does China need to adopt pinyin (or another alphabetic or syllabic script) as the standard? The Chinese government is certainly trying to reduce study pressures in primary schools, but this is resisted by schools, teachers, parents and universities, and so far, this sort of reform has failed. But China needs to do something, because the problem with the epidemic of myopia is not that so many children need glasses, but that around 20% of young adults have such severe myopia that they are at markedly increased risk of longer-term visual impairment and blindness, well before the classical age-related diseases which cause vision loss emerge.


  1. DMT said,

    February 1, 2015 @ 6:16 am

    A minor point: unlike the gaokao, the keju was not a "system in which one examination determined your social place for life," since it was common to take the keju exams multiple times. (There are contemporary stories of students taking the gaokao multiple times in the hope of getting into a more prestigious university, but such students represent a tiny minority of those taking the exam. Under the keju system, multiple attempts were standard and passing on the first attempt was unusual.)

  2. JQ said,

    February 1, 2015 @ 8:15 am

    As an anecdote, everyone in my family has become myopic between the ages of 5 and 10, but only the older generations were learning Chinese characters at that age.

  3. Shubert said,

    February 1, 2015 @ 9:46 am

    Older leaders of PRC like Mao, Zhou do wear glasses when in private, but not in public. The new leaders are more of myopias except Xi, who was sent to do labor and exercise regularly plus he was in good nutrition at childhood.

  4. Eidolon said,

    February 2, 2015 @ 6:14 pm

    The case of myopia in South Korea makes it difficult to argue that character learning is the primary cause for over-studying in East Asian nations. I am told that their alphabet is relatively easy to learn and school time not extraordinarily long, but that children end up going to 4-5 hours of after school tutoring in order to keep up with the highly competitive scholastic environment, in which academic success decides one's place in society. East Asian countries do not, in my opinion, view education as a way to acquire competence, but as a social competition in which perfection is the only acceptable outcome.

    To the degree that such an attitude leads to mass myopia, it is obviously not healthy. One's able to imagine basic policy changes that encourage children to be outdoors for 2-3 hours a day, but that's a matter for academic ministries to solve.

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