By Michael Hutton
Improve eyesight for children - especially in terms of reducing the risk of short-sightedness (myopia) - by ensuring they spend at least 10-14 hours per week outdoors is the conclusion of a new study from the University Of Sydney's Faculty of Health Sciences led by Kathryn Rose. Whilst there has been considerable conjecture that the rapid growth of myopia in children is related to the substantial amount of time they now spend on near vision activities such as computers, TVs, mobile phones and reading, Rose points out that many epidemiological studies have examined this issue and have found no association between time spent using digital media and the development of myopia.
Instead, Rose points out that her results on the importance of exposure to outdoor light as a means of reducing the risk of developing myopia corroborate findings from other studies undertaken in the U.S., Singapore and China. Myopia occurs when the eye elongates and light then focuses in front of the retina rather than directly on it. However, it is believed that release of retinal dopamine - a chemical produced naturally within the eye which is a known inhibitor of eye growth - is stimulated by light and this hypothesis has been supported by the results of animal tests. Given a tenfold difference in light levels between natural sunlight and artificial indoor lighting, more time spent outdoors is therefore likely to improve eyesight for children.
When considering the very high levels of myopia prevalence in China and other countries in the Far East, Rose points out that these countries are characterised by highly urbanized populations who have a particular focus on academic success at a young age. As such, time is predominantly spent indoors studying but the issue is not this greater amount of time spent on near work but rather that this is done under a much lower level of artificial light. Hence whilst there are other significant benefits for children from spending more time on outdoor activities such as improved health and fitness, it now seems that various studies conclude that doing so can improve eyesight and help mitigate the risk of developing myopia.
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