Evidence That Myopia Has a Strong Environmental Cause

Time reports on a new study on why Asians have a higher rate of nearsightedness:

It has long been thought that nearsightedness is mostly a hereditary problem, but researchers led by Ian Morgan of Australian National University say the data suggest that environment has a lot more to do with it.

Reporting in the journal Lancet, the authors note that up to 90% of young adults in major East Asian countries, including China, Taiwan, Japan, Singapore and South Korea, are nearsighted. The overall rate of myopia in the U.K., by contrast, is about 20% to 30%.

“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, which is the structural basis of myopia — the eye simply grows too big.” Morgan notes that both Chinese and Caucasian children living in Australia have lower rates of nearsightedness.