title: The influence of near work on myopic refractive change in urban students in Beijing: a three-year follow-up report.
abstract: OBJECTIVE
  To investigate the influence of daily activities on myopic refractive change and myopic onset in Chinese urban students.
  
  
  METHODS
  The Beijing Myopia Progression Study was a 3-year cohort study. Cycloplegic refraction and a daily activity questionnaire were assessed at baseline and at follow-up examinations. Refractive change was defined as the difference in cycloplegic spherical equivalent (SE) between the final follow-up and baseline. 386 students were initially enrolled in the baseline study.
  
  
  RESULTS
  At the final follow-up, 222 students (57.5 %) with completed refractive error and daily activity data were analyzed. These students spent 0.32 ± 2.33 h/day more on near work (p = 0.04), and 0.21 ± 1.31 h/day less on outdoor leisure (p = 0.02), than they did at baseline. In the multivariate analysis, the younger among the secondary students (β = 0.06, p < 0.001), and those with more near work hours at baseline (β = -0.028, p = 0.033), exhibited more myopic refractive change. However, myopic refractive change was not found to be significantly associated with near work hours in the primary students, or with time spent outdoors, in either school level. After stratifying the activity hours into quartile groups, students with a greater near work load at baseline (trend P = 0.03) exhibited a greater myopic refractive change and had a higher risk to develop myopia (hazard ratio, 95 % confidence interval: 5.19, 1.49-18.13), after adjusting for the confounders. However, no significant association was found related to outdoor activity.
  
  
  CONCLUSIONS
  In this cohort, children with a greater near work load at baseline exhibited more myopic refractive change and were also more likely to develop myopia. The protective effect of outdoor activity on myopic refractive change was not observed.
authors.affiliation: The Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, No. 270 West College Road, Wenzhou, Zhejiang, 325027, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Lin
authors.affiliation: College of Optometry, Mid Western University, Glendale, AZ, USA.
authors.forename: Balamurali
authors.initials: B
authors.lastname: Vasudevan
authors.affiliation: The Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, No. 270 West College Road, Wenzhou, Zhejiang, 325027, China.|School of Environmental Science & Public Health, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Guang Yun
authors.initials: GY
authors.lastname: Mao
authors.affiliation: Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY, USA.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ciuffreda
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Vishal
authors.initials: V
authors.lastname: Jhanji
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Beijing, China.
authors.forename: Xiao Xia
authors.initials: XX
authors.lastname: Li
authors.affiliation: The Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, No. 270 West College Road, Wenzhou, Zhejiang, 325027, China.
authors.forename: Hong Jia
authors.initials: HJ
authors.lastname: Zhou
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Science Key Laboratory, Beijing, China.
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
authors.affiliation: The Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, No. 270 West College Road, Wenzhou, Zhejiang, 325027, China. yuanboliang@126.com.
authors.forename: Yuan Bo
authors.initials: YB
authors.lastname: Liang
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D017668:Age of Onset; D002648:Child; D002681:China / Q000453:epidemiology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D009216:Myopia / Q000453:epidemiology / Q000503:physiopathology*; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies; D012574:Schools; D013334:Students; D011795:Surveys and Questionnaires; D013997:Time Factors; D014505:Urban Population; D014787:Vision Tests
keywords: Myopia; Myopia onset; Myopia refractive change; Near work; Outdoor activity