title: Prevalence of myopia in schoolchildren in Ejina: the Gobi Desert Children Eye Study.
abstract: OBJECTIVE
  To determine the prevalence and associations of myopia in schoolchildren in provincial Western China.
  
  
  METHODS
  In the school-based observational cross-sectional Gobi Desert Children Eye Study, cylcoplegic refractometry as part of a comprehensive ophthalmic examination was performed in all schools in the oasis region of Ejina. Out of 1911 eligible children, 1565 (81.9%) children with a mean age of 11.9 ± 3.5 years (range, 6-21 years) participated.
  
  
  RESULTS
  The mean refractive error in the worse eye was -1.38 ± 2.04 diopters (D) (median, -0.88 D; range, -13.00 to +6.50 D). In multivariate analysis, more myopic refractive errors were associated with older age (P < 0.001; regression coefficient B: -0.26; 95% confidence interval [CI]: -0.28, -0.23), female sex (P = 0.005; B: -0.26; 95%CI: -0.43, -0.08), more myopic paternal refractive errors (P < 0.001; B: 0.20; 95%CI: 0.14, 0.27), more myopic maternal refractive errors (P < 0.001; B: 0.18; 95%CI: 0.12, 0.24), and fewer hours spent outdoors (P = 0.038; B: 0.18; 95%CI: 0.01, 0.35). The prevalence of myopia, defined as refractive errors (spherical equivalent) of ≤-0.50, ≤-1.00, and ≤-6.00 D in the worse eye, was 60.0 ± 1.2%, 48.0 ± 1.3%, and 2.9 ± 0.4%, respectively. The prevalence of high myopia (≤-6.00 D) was 2.9 ± 0.4% in the whole study population, and it was 9.9 ± 3.0% in 17-year-olds. It was not associated with time spent outdoors (P = 0.66).
  
  
  CONCLUSIONS
  Even in Western China, prevalence of myopia in schoolchildren is high. As in East China, low and medium myopia was associated with less time spent outdoors. High myopia was not significantly associated with outdoors time. Compared with the myopia prevalence in elderly Chinese populations, the relatively high myopia prevalence in schoolchildren in China predicts a marked increase in vision-threatening high myopia in future elderly populations in China.
authors: The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
authors: Kai
authors: K
authors: Guo
authors: The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
authors: Da Yong
authors: DY
authors: Yang
authors: The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
authors: Yan
authors: Y
authors: Wang
authors: The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
authors: Xian Rong
authors: XR
authors: Yang
authors: The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
authors: Xin Xia
authors: XX
authors: Jing
authors: The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
authors: Yuan Yuan
authors: YY
authors: Guo
authors: The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
authors: Dan
authors: D
authors: Zhu
authors: Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
authors: Qi Sheng
authors: QS
authors: You
authors: Department of Ophthalmology, People's Hospital, Peking University, & Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing, China.
authors: Yong
authors: Y
authors: Tao
authors: Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China Department of Ophthalmology, Medical Faculty Mannheim of the Ruprecht-Karls-University Heidelberg, Seegartenklinik Heidelberg, Germany.
authors: Jost B
authors: JB
authors: Jonas
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D003906:Developing Countries; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D009216:Myopia / Q000175:diagnosis / Q000453:epidemiology*; D012029:Refraction, Ocular; D015351:Vision Screening; D055815:Young Adult
keywords: myopia; myopic shift; refractive error