title: Prevalence and causes of amblyopia in a rural adult population of Chinese the Handan Eye Study.
abstract: OBJECTIVE
  To determine the prevalence of and factors associated with amblyopia in a rural Chinese population.
  
  
  METHODS
  Population-based, cross-sectional study.
  
  
  METHODS
  Six thousand eight hundred thirty Han Chinese aged 30 years or more, recruited from Yongnian County, Handan, Hebei Province, China.
  
  
  METHODS
  Thirteen villages in the Yongnian County of Handan were selected randomly, and residents of these selected villages 30 years of age or older were invited to participate in the Handan Eye Study. Participants underwent a comprehensive eye examination, including standardized visual acuity (VA) tests using logarithm of the minimum angle of resolution charts. Prevalence rates were age- and gender-standardized to the 2000 China census.
  
  
  METHODS
  The proportion of rural Chinese population aged 30 years or older with amblyopia. Unilateral amblyopia was diagnosed if best-corrected VA (BCVA) was 20/32 or worse in the amblyopic eye and was not attributable directly to any underlying structural abnormality of the eye or visual pathway. Bilateral amblyopia was diagnosed if BCVA was 20/32 or less in both eyes and if there was a history of form deprivation during the sensitive period of visual development, such as media opacities or high, uncorrected ametropia.
  
  
  RESULTS
  Amblyopia was diagnosed in 205 participants, with an age- and gender-adjusted prevalence of 2.8%. Of these, 1.7% were unilateral cases and 1.1% were bilateral cases. Underlying causes included anisometropia (67.3%), strabismus (5.4%), mixed strabismus and anisometropia (4.4%), visual deprivation (9.8%), astigmatism association (9.8%), and other (3.4%). Of the amblyopia cases, 47.6% were hypermetropic.
  
  
  CONCLUSIONS
  In this rural Chinese population, 2.8% of adults 30 to 80 years of age had amblyopia, a prevalence rate broadly consistent with that of most other studies. One third of the cases were bilateral, and anisometropia was the most common cause of this condition.
authors.affiliation: Beijing Tongren Eye Center, Capital Medical University, Beijing Ophthalmology & Visual Science Key Laboratory, Beijing, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
authors.forename: Yuan Bo
authors.initials: YB
authors.lastname: Liang
authors.forename: Lan Ping
authors.initials: LP
authors.lastname: Sun
authors.forename: Xin Rong
authors.initials: XR
authors.lastname: Duan
authors.forename: Rui Zhi
authors.initials: RZ
authors.lastname: Yuan
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
authors.forename: Peng
authors.initials: P
authors.lastname: Yi
authors.forename: David S
authors.initials: DS
authors.lastname: Friedman
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000550:Amblyopia / Q000175:diagnosis / Q000208:ethnology* / Q000209:etiology*; D015858:Anisometropia / Q000150:complications; D044466:Asian People / Q000208:ethnology*; D001251:Astigmatism / Q000150:complications; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data*; D012683:Sensory Deprivation; D017678:Sex Distribution; D013285:Strabismus / Q000150:complications; D014792:Visual Acuity / Q000502:physiology