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More Time Outside Tied To Less Nearsightedness In Children
Bookworm09 writes: For primary school children in China, spending an extra 45 minutes per day outside in a school activity class may reduce the risk of myopia, according to a new study. In some parts of China, 90% of high school graduates have nearsightedness, and rates are lower but increasing in Europe and the Middle East, the authors write. "There were some studies suggesting the protective effect of outdoor time in the development of myopia, but most of this evidence is from cross-sectional studies (survey) data that suggest 'association' instead of causality," said lead author Dr. Mingguang He of Sun Yat-sen University in Guangzhou. "Our study, as a randomized trial, is able to prove causality and also provide the high level of evidence to inform public policy."
From here:
In 2009, Regan Ashby, Arne Ohlendorf and Frank Schaeffel from the University of Tubingen's Institute for Ophthalmic Research in Germany showed that high illumination levels - comparable to those encountered outside - slowed the development of experimentally induced myopia in chicks by about 60% compared with normal indoor lighting conditions
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