title: Role of near work in myopia: findings in a sample of Australian school children.
abstract: OBJECTIVE
  To examine the association of time spent in near work and reading with spherical equivalent refraction (SER) in a population-based sample of 12-year-old Australian schoolchildren.
  
  
  METHODS
  Data on the time spent in near-work or outdoor activities per week and estimates for the duration of continuous reading and reading distances, were collected in questionnaires (2353 participants, 75.3% response) in the Sydney Myopia Study between 2004 and 2005; 2339 children underwent a comprehensive eye examination, including cycloplegia.
  
  
  RESULTS
  Longer time spent on reading for pleasure and reports of close reading distance (< 30 cm) were associated with a more myopic refraction after adjustment for age, sex, ethnicity, and school type (P(trend) = 0.02 and P = 0.0003, respectively). Time spent in individual near-work activities, however, correlated poorly with SER (all r < or = 0.2) and was not significant in multivariate analyses for myopia (SER < or = -0.50 D), with adjustment for age, sex, ethnicity, parental myopia, school type, and outdoor activity. Children of European Caucasian ethnicity reported spending marginally less time in near work than children of East Asian ethnicity (26.0 h/wk vs. 32.5 h/wk, P < 0.0001). East Asian ethnicity, however, was associated with substantially greater odds of having myopia (odds ratio [OR], 11.0; 95% confidence interval [CI], 7.0-17.4). Near work such as close reading distance (< 30 cm) and continuous reading (> 30 minutes) independently increased the odds of having myopia in this sample of children.
  
  
  CONCLUSIONS
  Although myopia was not significantly associated with time spent in near work after adjustment for other factors, there were significant independent associations with close reading distance and continuous reading. These associations may indicate that the intensity rather than the total duration of near work is an important factor.
authors.affiliation: Centre for Vision Research, Department of Ophthalmology and the Westmead Millennium Institute, University of Sydney, Sydney, Australia.
authors.forename: Jenny M
authors.initials: JM
authors.lastname: Ip
authors.forename: Seang-Mei
authors.initials: SM
authors.lastname: Saw
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Rose
authors.forename: Ian G
authors.initials: IG
authors.lastname: Morgan
authors.forename: Annette
authors.initials: A
authors.lastname: Kifley
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D000293:Adolescent; D044466:Asian People / Q000706:statistics & numerical data; D001699:Biometry; D002648:Child; D005123:Eye / Q000473:pathology; D005192:Family Health; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009216:Myopia / Q000208:ethnology / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D016017:Odds Ratio; D010290:Parents; D011932:Reading; D012029:Refraction, Ocular; D012574:Schools; D012737:Sex Factors; D013334:Students; D011795:Surveys and Questionnaires; D013997:Time Factors; D044465:White People / Q000706:statistics & numerical data