Short-Sightedness Was Rare. In Asia, It Is Becoming Ubiquitous

Researchers have found that being outside drastically reduces the risk of developing short-sightedness. From a report: In the early 1980s Taiwan's army realised it had a problem. More and more of its conscripts seemed to be short-sighted, meaning they needed glasses to focus on distant objects. "They were worried that if the worst happened [ie, an attack by China] their troops would be fighting at a disadvantage," says Ian Morgan, who studies myopia at Australian National University, in Canberra. An island-wide study in 1983 confirmed that around 70% of Taiwanese school leavers needed glasses or contact lenses to see properly. These days, that number is above 80%. But happily for Taiwan's generals, the military disparity has disappeared. Over the past few decades myopia rates have soared across East Asia (see chart 1 in the linked story). In the 1960s around 20-30% of Chinese school-leavers were short-sighted. These days they are just as myopic as their cousins across the straits, with rates in some parts of China running at over 80%. Elsewhere on the continent things are even worse. One study of male high-school leavers in Seoul found 97% were short-sighted. Hong Kong and Singapore are not far behind. And although the problem is worst in East Asia, it is not unique to it. Reliable numbers for America and Europe are harder to come by. But one review article, published in 2015, claimed a European rate of between 20% and 40% -- an order of magnitude higher than that which people working in the field think is the "natural," background rate. For most of those affected, myopia is a lifelong, expensive nuisance. But severe myopia can lead to untreatable vision loss, says Annegret Dahlmann-Noor, a consultant ophthalmologist at Moorfields Eye Hospital, in London. A paper published in 2019 concluded that each one-dioptre worsening in myopia was associated with a 67% increase in prevalence of myopic maculopathy, an untreatable condition that causes blindness. (A dioptre is a measure of a lens's focusing power.) In some parts of East Asia, 20% of young people have severe myopia, defined as -6 dioptres or worse (see chart 2 in linked story). "This is storing up a big problem for the coming decades," says Kathryn Rose, head of orthoptics at the University of Technology, Sydney.

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