Children Spending More Time Outdoors Less Likely To Become Nearsighted
Spending two to three hours a day outdoors can markedly lower a child’s risk of developing myopia or nearsightedness, according to a paper appearing in the January issue of Optometry and Vision Science. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, pharmacy and the pharmaceutical industry.
Myopia is the leading eye disability in the world: a “significant global public health concern,” according to Terri Young, PhD, of the Duke University Medical Center’s Department of Ophthalmology. About one-third of U. S. adults suffer from it, and the number of individuals with myopia is estimated to grow from 1.6 billion worldwide today to 2.5 billion by the year 2020 (Institute of Eye Research (IER) Annual Report 2006-7.)
According to the research published in Optometry & Vision Science, the critical factor for reducing the development of myopia in children seems to be total time spent outdoors during daylight hours. Sports or physical activity does not appear to play a role: studies found that both active and passive outdoor activities had a protective effect on vision, while sports played indoors were found not to have this effect. One of the issue’s guest editors, Donald Mutti, OD, PhD, FAAO, reports that a child’s chances of becoming myopic--if he or she has two myopic biological parents--are about 6 in 10 for children engaging in 0-5 hours per week of outdoor activity, but the risk drops to 2 in 10 when outdoor activity exceeds 14 hours a week.
The report, authored by Neville A. McBrien, MCOptom, PhD et al, is entitled “"Myopia: Recent Advances in Molecular Studies; Prevalence, Progression and Risk Factors; Emmetropization; Therapies; Optical Links; Peripheral Refraction; Sclera and Ocular Growth; Signalling Cascades; and Animal Models." It includes findings presented at the 12th International Myopia Conference in Australia in July 2008. Supporting data includes:
• The Orinda Longitudal Study of Myopia shows that children with the risk factor for myopia of myopic parents, provided they spend sufficient time outside, are at only slightly greater risk than children without myopic parents.
• The Sydney Myopia Study, conducted with schoolchildren of European origin, indicates that greater time spent outside can override the greater risk associated with near work and schoolwork.
• The Singapore SCORM Study, which presented data similar to the Orinda and Sydney studies, but was conducted with children of Chinese, Malay, and Indian origin, suggests that the effect is likely to span ethnic groups.
The agreement among the above studies is unusual in the field of myopia research, according to Donald Mutti. “It’s a field generally renowned for its controversies rather than consensus.”
What are the exact mechanisms underlying the protective effects of outdoor time? “The features of outdoor activity (e. g. sunlight, distance viewing) that may be protective against myopia development remain to be determined,” state two contributors to the research, Jane Gwiazda, PhD and Li Deng of the New England College of Optometry in Boston.
By The American Academy of Optometry
The American Academy of Optometry, the society associated with the journal Optometry and Vision Science, and the publisher, Lippincott Williams & Wilkins, plan to make the entire January issue of Optometry and Vision Science available on an open-access basis upon publication.
This page is updated on May 2, 2013.