90% of Asian Kids Wear Glasses: Few Hours in the Sunlight Could Prevent This

The short version: In 2012, researchers reported that an epidemic of myopia — nearsightedness — was sweeping through East Asian children, and the prime suspect wasn't genetics but the indoor life. Up to 90% of young adults in major East Asian countries were nearsighted, and the more hours children spent studying indoors, the worse it got. The proposed fix was almost embarrassingly simple: a couple of hours of sunlight a day.

How bad was it?

The numbers, reported by Time's Healthland in May 2012, were startling. Up to 90% of young adults in China, Taiwan, Japan, Singapore, and South Korea were nearsighted. In the United Kingdom, by contrast, the overall rate was about 20% to 30%.

Nearsightedness had long been assumed to be mostly hereditary. But researchers led by Ian Morgan of the Australian National University, writing in the Lancet, argued that the data pointed at environment instead.

Why environment, not genes?

The clue came from Singapore, where rates of nearsightedness had risen sharply since 1996 across three different ethnic groups — Chinese, Indian, and Malay — in equal measure. If genes were driving the rise, the three groups shouldn't move together. That they did suggested a common environmental factor: the pressure-cooker school life they all shared.

A second clue came from migration. Ethnic Chinese young adults in Australia, where bright sunlight is a way of life, showed lower myopia rates than their counterparts in East and Southeast Asian cities. White children in Sydney were less nearsighted than white children in the UK. The variable that tracked the difference wasn't ancestry — it was light.

The dopamine theory

The proposed mechanism runs through a neurotransmitter. Bright outdoor light stimulates the release of dopamine in the retina, and dopamine appears to block the axial growth of the eyeball — the structural basis of myopia, in which the eye grows too long and incoming light focuses in front of the retina instead of on it. Animal experiments in mice and monkeys supported the theory.

"There is a pretty well-confirmed mechanism," Morgan said at the time. "We postulate that bright outdoor light would stimulate the release of the retinal transmitter dopamine, which is known to be able to block the axial growth of the eye."

The concern wasn't just glasses. About 10% to 20% of Asian schoolchildren had high myopia, which raises the risk of serious vision problems, including blindness, in adulthood. And because the study pressure hit children early — often in elementary school — the eye had more years to keep elongating.

What could parents do?

The honest answer in 2012: there was no proven prevention beyond corrective lenses. The drug atropine slowed eye growth, but with side effects and diminishing effectiveness. Morgan himself said more evidence was needed on everything that had been tried.

What the researchers did recommend was practical and free — give hard-studying children regular breaks outdoors. A couple of hours of sunlight a day, they suggested, would probably do it. Not less studying, just more daylight around it.

The finding has an old echo. Ayurveda's dinacharya — the traditional daily routine — has long included morning eye-care practices: cold-water eye splashes, gazing exercises, rest for tired eyes. That tradition never claimed to cure nearsightedness, and neither does this; but it is a reminder that the idea of eye rest is older than the research. If that framing interests you, Swastik's guide to dinacharya is a good place to explore it.