Myopia in East Asia

Over my decades of watching television and old movies with actors of Oriental descent, I never really took note of the fact that most of the characters depicted wore glasses and, usually, they had very thick lenses. Whether it was Charlie Chan solving a mystery or John Wayne fighting the Japanese, just about all East Asians sported spectacles. And, right off, I can't recall any exceptions.

Now, any prudent, thinking and curious individual would probably have voiced the observation, "Boy! It seems the Orientals generally have poor eyesight." Apparently I wasn't prudent, thinking nor curious because it never occurred to me. That is, until recently.

Enlightenment came through reading Glass : a world history by Alan Macfarlane and Gerry Martin, published by the University of Chicago Press. The book documents their well-reasoned study of glass from its discovery to the present. And, although interesting throughout, the section I found most intriguing examined the use of glass in correcting nearsightedness.

Empirical data from previous centuries to the present were used to conclude, infer, and suggest the causes of large differences in myopia rates exhibited by various groups and populations.

Some examples are:

Data surveyed establish a general myopia rate between 20% and 30% for adult Europeans.

Data indicate a general myopia rate between 65% and 80% for adult Chinese.

Data put the myopia rate between 70% and 80% for adult Japanese.

The authors examined three primary causal factors to try and explain the gross disparities among these groups. Nutrition among the three populations was studied and determined to be a factor, but insufficient to be considered the primary cause. Heredity was also examined, also determined to be a factor, but not significant enough to explain the differences.

With strong supporting data, the one factor appearing to have the greatest impact on myopia rates in a population is eyestrain, especially in young children.

The authors found that all Chinese and Japanese children start at a very young age learning the language, committing to memory two to three thousand complex characters while practicing writing them in an accurate and artistic manner. It's estimated that these children spend fully half their time in school studying language. The result is severe and continuous eyestrain for many long years. Without exception, all the places that require children to learn and become proficient with Chinese/Japanese characters have high rates of myopia in the population. This includes Singapore, the Malay Peninsula and Taiwan, but, interestingly, not South Korea.

" . . . the Koreans developed a phonetic script (hangul), with a small character set, in the fifteenth century and this is now used in all teaching until high school. So language learning constitutes only about one sixth, rather than a half, of the school lessons. One has the school pressure, but one does not have the Chinese characters in the earlier years of school."

Consequently, the general myopia rate in Korea (30% to 35%), although higher than in Europe, is not nearly as high as in China or Japan.

I choose to mention this research in my blog because I think some other folks will find the subject as interesting as I do.