Increasingly we are seeing kids in primary school getting specs. Andrew Herbert, a vision scientist, notes that myopia is rising rapidly across the world: “Myopia, or the need for corrected vision to focus or see objects at a distance, has become a lot more common in recent decades. Some even consider myopia, also known as nearsightedness, an epidemic.
Optometry researchers estimate that about half of the global population will need corrective lenses to offset myopia by 2050 if current rates continue – up from 23% in 2000 and less than 10% in some countries.”
So what is causing this surge in myopia? Mr Herbert begins by explaining how myopia develops (note: myopia is NOT genetic): “Optometrists have learned a great deal about the progression of myopia by studying visual development in infant chickens. They do so by putting little helmets on baby chickens. Lenses on the face of the helmet cover the chicks’ eyes and are adjusted to affect how much they see.
Just like in humans, if visual input is distorted, a chick’s eyes grow too large, resulting in myopia. And it’s progressive. Blur leads to eye growth, which causes more blur, which makes the eye grow even larger, and so on.”
This research on chickens is helping scientists understand that spending a lot of time reading is potentially a driver of myopia: “Two recent studies featuring extensive surveys of children and their parents provide strong support for the idea that an important driver of the uptick in myopia is that people are spending more time focusing on objects immediately in front of our eyes, whether a screen, a book or a drawing pad. The more time we spend focusing on something within arm’s length of our faces, dubbed “near work,” the greater the odds of having myopia.
So as much as people might blame new technologies like smartphones and too much “screen time” for hurting our eyes, the truth is even activities as valuable as reading a good book can affect your eyesight.”
The second driver appears to be lack of daylight: “Other research has shown that this unnatural eye growth can be interrupted by sunlight.
A 2022 study, for example, found that myopia rates were more than four times greater for children who didn’t spend much time outdoors – say, once or twice a week – compared with those who were outside daily. At the same time, kids who spent more than three hours a day while not at school reading or looking at a screen close-up were four times more likely to have myopia than those who spent an hour or less doing so.
In another paper, from 2012, researchers conducted a meta-analysis of seven studies that compared duration of time spent outdoors with myopia incidence. They also found that more time spent outdoors was associated with lower myopia incidence and progression. The odds of developing myopia dropped by 2% for each hour spent outside per week.
Other researchers have reported similar effects and argued for much more time outdoors and changes in early-age schooling to reduce myopia prevalence.”
Vision scientists who are reading this piece should be able test for the above in India – kids in Mumbai spend very little time outdoors as the city has very few outdoor spaces to play in. In contrast, India’s smaller cities eg. Chandigarh, Indore, Jaipur fair better in this regard. So testing the vision of kids in Mumbai vs these other cities should provide more evidence on the drivers of myopia. Mr Herbert notes that fast growing East Asian economies eg. Singapore, China, Japan which have very little by way of open spaces in their overcrowded cities have exactly the same problem that children in Mumbai have.
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