title: Associations between near work, outdoor activity, and myopia among adolescent students in rural China: the Xichang Pediatric Refractive Error Study report no. 2.
abstract: OBJECTIVE
  To study the associations between near work, outdoor activity, and myopia among children attending secondary school in rural China.
  
  
  METHODS
  Among a random cluster sample of 1892 children in Xichang, China, subjects with an uncorrected acuity of 6/12 or less in either eye (n = 984) and a 25% sample of children with normal vision (n = 248) underwent measurement of refractive error. Subjects were administered a questionnaire on parental education, time spent outdoors, and weekly time spent engaged in and preferred working distance for a variety of near-work activities.
  
  
  RESULTS
  Among 1232 children with refraction data, 998 (81.0%) completed the near-work survey. Their mean age was 14.6 years (SD, 0.8 years), 55.6% were girls, and 83.1% had myopia of -0.5 diopters or less (more myopia) in both eyes. Time and diopter-hours spent on near activities did not differ between children with and without myopia. In regression models, time spent on near activities and time outdoors were unassociated with myopia, adjusting for age, sex, and parental education.
  
  
  CONCLUSIONS
  These and other recent results raise some doubts about the association between near work and myopia. Additional efforts to identify other environmental factors associated with myopia risk and that may be amenable to intervention are warranted.
authors.affiliation: Joint Shantou International Eye Center of Shantou University and Chinese University of Hong Kong, Shantou, Guangdong, China.
authors.forename: Bei
authors.initials: B
authors.lastname: Lu
authors.forename: Nathan
authors.initials: N
authors.lastname: Congdon
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Liu
authors.forename: Kai
authors.initials: K
authors.lastname: Choi
authors.forename: Dennis S C
authors.initials: DS
authors.lastname: Lam
authors.forename: Mingzhi
authors.initials: M
authors.lastname: Zhang
authors.forename: Mingwei
authors.initials: M
authors.lastname: Zheng
authors.forename: Zhongxia
authors.initials: Z
authors.lastname: Zhou
authors.forename: Liping
authors.initials: L
authors.lastname: Li
authors.forename: Xueyu
authors.initials: X
authors.lastname: Liu
authors.forename: Abhishek
authors.initials: A
authors.lastname: Sharma
authors.forename: Yue
authors.initials: Y
authors.lastname: Song
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D002681:China / Q000453:epidemiology; D003201:Computers / Q000706:statistics & numerical data; D005260:Female; D006302:Health Services Research; D006306:Health Surveys; D006801:Humans; D007899:Leisure Activities; D008297:Male; D009216:Myopia / Q000453:epidemiology*; D015995:Prevalence; D011932:Reading; D012029:Refraction, Ocular / Q000502:physiology; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data*; D017678:Sex Distribution; D011795:Surveys and Questionnaires; D014792:Visual Acuity / Q000502:physiology; D014937:Work