title: Prevalence and risk factors for myopia in second-grade primary school children in Taipei: A population-based study.
abstract: BACKGROUND
  High myopia is associated with multiple ocular morbidities that may lead to irreversible blindness. Because high myopia in an adult is thought to be related to onset of myopia in very early childhood, detecting myopia early and working to improve modifiable risk factors may help reduce the development of high myopia. In this study, we tried to evaluate the prevalence of myopia and associated risk factors in second-grade primary school children in Taipei, Taiwan.
  
  
  METHODS
  A questionnaire was distributed to the participants' parents, and their written informed consent was obtained before performing eye examinations that included visual acuity testing and cycloplegic autorefraction. Multiple logistic regression models were applied to assess possible risk factors associated with myopia. Myopia was defined as spherical equivalent of -0.50 D or less in either eye.
  
  
  RESULTS
  The prevalence of myopia in the second graders was 36.4%. After adjustment for other characteristics, the following variables were significantly associated with a higher risk of myopia: male sex [odds ratio (OR)=1.24, p<0.001]; suburban residence (vs. urban; OR=1.10, p=0.02); lower maternal education level (OR=1.25, p<0.001); the presence of myopia in one parent (OR=1.66, p<0.001) or both parents (OR=2.82, p<0.001); time spent on near-work activity every day (OR=1.21, p<0.001); shorter visual distance when doing near-work activity (OR=1.17, p<0.001); and participation in an after-school tutorial program (OR=1.20, p<0.001). By contrast, resting after 30 minutes of near-work activity (OR=0.84, p<0.001) and spending more time participating in outdoor activities on weekends (OR=0.91, p=0.03) were significantly associated with a lower risk of myopia.
  
  
  CONCLUSIONS
  Our findings indicate that lifestyle and reading habits impact the development of myopia during early childhood. Behavior modification, such as more time spent outside during the day and limited near-work activity, may be a feasible strategy for curbing the increasingly high prevalence of myopia in Taipei.
authors.affiliation: Department of Ophthalmology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan, ROC; General Education Center, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan, ROC.
authors.forename: Chih-Chien
authors.initials: CC
authors.lastname: Hsu
authors.affiliation: Institute of Hospital and Health Care Administration, National Yang-Ming University, Taipei, Taiwan, ROC.
authors.forename: Nicole
authors.initials: N
authors.lastname: Huang
authors.affiliation: Department of Ophthalmology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC.
authors.forename: Pei-Yu
authors.initials: PY
authors.lastname: Lin
authors.affiliation: Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC; Department of Ophthalmology, National Yang-Ming University Hospital, Yilan, Taiwan, ROC.
authors.forename: Der-Chong
authors.initials: DC
authors.lastname: Tsai
authors.affiliation: Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC; Department of Ophthalmology, Taipei City Hospital, Taipei, Taiwan, ROC.
authors.forename: Ching-Yao
authors.initials: CY
authors.lastname: Tsai
authors.affiliation: Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC; Department of Ophthalmology, Taipei City Hospital, Taipei, Taiwan, ROC.
authors.forename: Lin-Chung
authors.initials: LC
authors.lastname: Woung
authors.affiliation: Department of Ophthalmology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC. Electronic address: jlliu@vghtpe.gov.tw.
authors.forename: Catherine Jui-Ling
authors.initials: CJ
authors.lastname: Liu
mesh_terms: D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D009216:Myopia / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D011932:Reading; D012307:Risk Factors; D012574:Schools; D013624:Taiwan
keywords: myopia; population-based study; prevalence; risk factor; schoolchildren