Culture & Society Health Nature

Natural light prevents myopia

A report issued in Nature reveals that staying inside is the leading cause of myopia.

The finding refutes the myth that nearsightedness is the result of intense reading sessions and screen activity.

Myopia is prevalent in East Asian countries, where the focus on studying means staying indoors rather than benefiting from the outside environment.

According to another study in journal Lancet, 90% of young adults in China, Taiwan, Japan, Singapore, and South Korea are nearsighted compared to 30% in Britain.

Outdoor light is beneficial to the eyes because it triggers the release of dopamine in the retina.

One myopia researcher recommends spending at least three hours a day in natural light, even if means sitting under a tree.

But what scientists really needed was a mechanism: something to explain how bright light could prevent myopia. The leading hypothesis is that light stimulates the release of dopamine in the retina, and this neurotransmitter in turn blocks the elongation of the eye during development. The best evidence for the ‘light–dopamine’ hypothesis comes — again — from chicks. In 2010, Ashby and Schaeffel showed that injecting a dopamine-inhibiting drug called spiperone into chicks’ eyes could abolish the protective effect of bright light 11 .

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