There is one in three people. Why are there more and more Chinese people with myopia?

Abstract: what is myopia. In short, your eyes contract or relax the muscles that control the lens in order to see a nearby or distant object, so that the shape of the object can be projected onto the retina. Myopia is due to the lengthening of the eyeball. After the light comes in, it does not focus on the retina, but on a little bit in front.

China is already a big country that can’t see clearly, and the number of myopia is the first in the world. Genetics alone cannot explain such a wide range of myopia, and books and television may only be scapegoats for myopia.

when you see this article, you might as well look around you and observe your colleagues, your classmates and strangers around you. You will find that most people wear glasses, and you don’t have to ask. Most of them are myopic.

myopia, as an epidemic, has only appeared on a large scale in China in recent decades. In 2014, the economist reported that in the 1970s, less than one-third of Chinese teenagers aged 16-18 were myopia. But today, nearly four fifths of teenagers suffer from myopia.

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the national visual health report released by Peking University in 2016 also shows that China’s myopic population over the age of 5 has reached 450 million and will exceed 700 million in 2020. China has become a truly invisible country.

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have been suffering from myopia in East Asia except for Chinese mainland. In Hong Kong, Taiwan, Japan, South Korea and Singapore, nine out of ten students who finish high school are myopic, of which 10% – 20% are highly myopic.

in Seoul, South Korea, the myopia rate of 19-year-old boys has even reached an incredible 96.5%. Considering the cultural similarity in East Asia, the trouble they encounter is of course the trouble of Chinese mainland.

so why are there more and more East Asians, especially Chinese, with myopia? Are Chinese people naturally prone to myopia? Or are the Chinese all learning maniacs who grow up gnawing at books?

parents decide your eyesight?

we have to answer a question first, what is myopia. In short, your eyes contract or relax the muscles that control the lens in order to see a nearby or distant object, so that the shape of the object can be projected onto the retina. Myopia is due to the lengthening of the eyeball. After the light comes in, it does not focus on the retina, but on a little bit in front.

myopia is certainly not as terrible as cancer or heart disease, but the large-scale prevalence of myopia brings more than the inconvenience of wearing glasses. In particular, high myopia may not be a big deal when young, but it is easy to induce cataract and glaucoma after middle age.

for many years, scientists have blamed myopia on genes. In the 1960s, research was done in this direction, For example, a study found that identical twins (genetically identical) are more likely to get myopia than fraternal twins, which shows that the effect of DNA on myopia should not be underestimated. Scientists have found more than 100 regions in the genome related to myopia.

If the parents are myopic, the child is indeed more likely to be myopic. In 2012, a joint study by Sun Yat sen University and Australian National University showed that among 15-year-old teenagers in Guangzhou, China, if a pair of parents are myopic, the child’s myopia rate will be as high as 83.3%; If one of the parents has myopia, the myopia rate of the child is a little worse, 88.9%; If parents have good eyesight, the child’s myopia rate will drop to 68.2%.

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but genes can’t explain the surge in the number of men and women with glasses in China. Genes can’t explain why the myopia rate of 15-year-old teenagers in Guangzhou, China is 78.4%, but only 19.8% of their parents have bad eyes. Genes cannot explain why the myopia rate in urban areas is higher than that in rural areas, especially among high school students.

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are the same, Genes can’t explain why 22.9% of 10-year-old students in Shaanxi (ranking 14 in per capita GDP) suffered from myopia in 2012, but the myopia rate of equivalent students in Gansu (ranking 30 in per capita GDP) next door was only 12.7%.

Heredity does play a role, but it is impossible to set off this wave of myopia only by itself. Contemporary myopia is not only a genetic problem, but also a social problem.

we may have wrongly blamed books and television

in order to catch the culprit of large-scale damage to vision, scientists tried to blame myopia on “nearwork”. After all, compared with European and American students, Chinese students have to spend more time on books.

according to a 2014 OECD report, 15-year-old students in Shanghai spend 14 hours a week doing their homework, while American students spend only 6 hours a week, and British students spend less, only 5 hours.

the myopia rate of Chinese students is rising, accompanied by the infinite extension of their learning time. In addition to learning to read endlessly, watching TV, playing with mobile phones and playing with computers have also become the object of parents’ blame. However, no matter how hard scientists try to associate “close work” with myopia, the causal relationship between them is not so strong.

in 2007, Ohio State University released a research result. They followed the eyesight of 514 American students in grade 3. Five years later, 111 students were found to have myopia. Myopia is related to parents’ heredity, sports and outdoor sports, but it has nothing to do with the length of reading a week.

later, members of the research team recalled to the journal Nature, “we think this is really a strange result”, “but when we do analysis, such results always appear”.

if you think Americans are not able to represent Asians, there are also studies in Asia. In 2006, the National University of Singapore conducted a three-year study on a group of 7-9-year-old Singaporean students. It was found that reading a few books a week could not be used to predict whether children would become close friends in the next few years