title: Design, methodology and baseline data of a school-based cohort study in Central China: the Anyang Childhood Eye Study.
abstract: OBJECTIVE
  To report the design, methods and baseline data of the Anyang Childhood Eye Study (ACES), aiming to determine the prevalence, incidence and risk factors of myopia and other ocular diseases in children in central China.
  
  
  METHODS
  The ACES was a school-based cohort study conducted in Anyang city. Students have been examined and will be followed-up annually for 3-5 years. Ocular examinations included visual acuity, identification of amblyopia and strabismus, ocular biometry, optical coherence tomography, retinal photography, cycloplegic autorefraction, accommodative response, peripheral refraction, visual perception and so on. A questionnaire survey was performed to collect risk factors for myopia including near work, outdoor activity, parental myopia, birth history, habits of wearing spectacles and reading, living habits, food habits and so on.
  
  
  RESULTS
  Of 3112 grade 1 and 2363 grade 7 students eligible for the ACES, 2893 (93.0%) and 2267 (95.9%) participated in the study, with a mean age of 7.1 years (range 5.7-9.3 years) and 12.7 years (range 10.0-15.9 years), and proportions of male to be 57.8% and 50.0%, respectively. The prevalence rates of myopia, high myopia, emmetropia and hyperopia were 3.9%, 0.1%, 72.9% and 23.3% in grade 1, and 67.3%, 2.7%, 31.4% and 1.2% in grade 7, respectively. Similar data were found in the children confined in 6-year-old and 12-year-old ages.
  
  
  CONCLUSIONS
  The ACES is the first large-scale cohort study in China with baseline response rates over 90%. Continuous documentation of changes and risk factors of refractive errors in these cohorts would provide new insights into myopia control in school-aged children.
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University , Beijing , China .
authors.forename: Shi-Ming
authors.initials: SM
authors.lastname: Li
authors.forename: Luo-Ru
authors.initials: LR
authors.lastname: Liu
authors.forename: Si-Yuan
authors.initials: SY
authors.lastname: Li
authors.forename: Ya-Zhou
authors.initials: YZ
authors.lastname: Ji
authors.forename: Jing
authors.initials: J
authors.lastname: Fu
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: He
authors.initials: H
authors.lastname: Li
authors.forename: Bi-Dan
authors.initials: BD
authors.lastname: Zhu
authors.forename: Zhou
authors.initials: Z
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Meng-Tian
authors.initials: MT
authors.lastname: Kang
authors.forename: Feng-Ju
authors.initials: FJ
authors.lastname: Zhang
authors.forename: Si-Yan
authors.initials: SY
authors.lastname: Zhan
authors.forename: Ning-Li
authors.initials: NL
authors.lastname: Wang
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000453:epidemiology*; D015994:Incidence; D008297:Male; D009216:Myopia / Q000453:epidemiology*; D015995:Prevalence; D012029:Refraction, Ocular / Q000502:physiology; D012107:Research Design; D012307:Risk Factors; D012574:Schools; D011795:Surveys and Questionnaires; D041623:Tomography, Optical Coherence; D014505:Urban Population / Q000706:statistics & numerical data; D014787:Vision Tests; D014792:Visual Acuity / Q000502:physiology