Perhaps the most valuable result of all education is the ability to make yourself do the thing you have to do, when it ought to be done, whether you like it or not. It is the first lesson that ought to be learned and however early a man's training begins, it is probably the last lesson that he learns thoroughly.

— Thomas Huxley, in Technical Education (1877)

For decades, researchers had thought myopia was mostly genetic. It runs in families, and genomic studies have turned up several gene variants which increase the risk of developing the condition. There were early hints, though, that this could not be the whole story. A study of Inuit in Alaska, published in 1969, found that myopia was virtually unknown in those middle-aged or older, but that rates were above 50% in older children and young adults. Such a change is much too fast to be purely genetic, and it had happened just as the study participants had begun to adopt a more settled, Westernised way of life. But the results went against the dogma of the day, says Dr Morgan, and were ignored.

The spike in East Asia, which occurred as places there industrialised, was harder to dismiss. Short-sightedness is stereotypically an affliction of the bookish, and a procession of studies has confirmed a strong, reliable link with education. “The more educated you are, and the higher your grades, and the more you participate in after-school classes and tutorials—the more likely you are [to be myopic]”, says Dr Morgan. And an intriguing study on orthodox Jewish children in Israel, in the 1990s, confirmed the link with long school hours. It showed that boys—who receive intensive religious education in addition to the normal curriculum—were more myopic than their sisters, who do not.

— the Economist