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K.A. Rose, J. Ip, D. Robaei, S.C. Huynh, A. Kifley, W. Smith, I.G. Morgan, P. Mitchell, The Sydney Myopia Study, Sydney Childhood Eye Study; Near–Work and Outdoor Activities and the Prevalence of Myopia in Australian School Students Aged 12–13 Years: The Sydney Myopia Study . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5453.
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To assess associations between near–work and outdoor activities and refractive status in 12–year old Australian students.
The Sydney Myopia Study randomly selected 22 secondary schools, stratified by socio–economic status. All Year 7 students were invited to participate. Cycloplegic autorefraction was performed. Parents and students completed separate questionnaires on near work and outdoor activities outside school hours. Myopia was defined as spherical equivalent ≤ –0.5D in at least one eye.
Of the 2367 students who participated (75.3% response rate), 2,000 are included in this analysis. Myopia prevalence was 12.7% (95% CI 11.2%–14.2%) in the overall sample, 5.4% (CI 3.8%–6.9%) in students with European Caucasian parents and 39.8% (CI 33.8%–45.7%) in those with East Asian parents. Students of East Asian origin spent significantly more time on near–work (4.4h/day, CI 4.2–4.6) and less time on outdoor leisure activity (1.2h/day, CI 1.1–1.4) than Caucasian children (3.5 h/day, CI 3.4–3.6 for near work; 1.8 h/day, CI 1.8–1.9 outdoors). The average time spent on near–work increased from 3.5 to 3.7 and to 4.0 h/day for children with none, one or two myopic parents, but the number of hours spent outdoors was not significantly different across parental myopia groups after adjusting for gender and ethnicity (p(trend)= 0.13). Hours spent on near–work was associated with an increased likelihood of myopia (OR 1.13, CI 1.03–1.23 per hour, after adjusting for gender and ethnicity, time spent outdoors was associated with a decreased likelihood of myopia (OR 0.77, CI 0.66–0.91). After further adjusting for parental myopia, the association between myopia and time spent outdoors remained significant (OR 0.78, CI 0.63–0.96), but the association between myopia and near–work was not (OR 1.10, CI 0.96–1.20).
The prevalence of myopia in Sydney was lower than in age–matched peers in urban East Asia. Parental myopia was positively associated with near–work, which was in turn positively associated with student myopia. Outdoor activity was negatively associated with myopia.
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