title: Prevalence of amblyopia and strabismus in a population of 7th-grade junior high school students in Central China: the Anyang Childhood Eye Study (ACES).
abstract: OBJECTIVE
  To determine the prevalence of amblyopia and strabismus in 7th-grade junior high school students in central China.
  
  
  METHODS
  Using stratified cluster sampling, 2363 7th-grade students were recruited from four junior high schools in Anyang city into the cross-sectional Anyang Childhood Eye Study (ACES). All students underwent visual acuity (VA), cycloplegic autorefraction, cover test, and ocular movement examinations. Uncorrected VA and best-corrected VA (BCVA) were measured with a logarithm of the minimum angle of resolution (logMAR) chart. Cycloplegic autorefraction was performed after administration of 1.0% cyclopentolate and Mydrin-P. Strabismus was defined as heterotropia at near or distance fixation. Amblyopia was defined as BCVA ≤ 0.1 logMAR units in one or both eyes, without ocular pathology in either eye.
  
  
  RESULTS
  Of the 2363 eligible students, 2260 (95.6%) completed all examinations. The mean age of the students was 12.4 ± 0.6 years. Amblyopia was present in 52 students (2.5%), of whom 33 (63.5%) had unilateral and 19 (36.6%) had bilateral amblyopia. Of those with unilateral amblyopia, 18 (54.5 %) had anisometropia and 7 (21.2%) had strabismus. Of those with bilateral amblyopia, 6 (31.6%) had significant refractive error. Strabismus was present in 108 students (5.0%), of whom 2 (1.9%) had esotropia, 102 (94.4%) had exotropia, 3 (2.8%) had vertical strabismus, and 1 (0.9%) had microstrabismus. Of the 108 students with strabismus, 9 (8.3%) had amblyopia.
  
  
  CONCLUSIONS
  The cross-sectional ACES which examined the prevalence of amblyopia and strabismus in 7th-grade students in central China revealed the prevalence of strabismus, particularly the proportion of exotropia, to be higher than previously reported.
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab , Beijing , China .
authors.forename: Jing
authors.initials: J
authors.lastname: Fu
authors.forename: Shi Ming
authors.initials: SM
authors.lastname: Li
authors.forename: Luo Ru
authors.initials: LR
authors.lastname: Liu
authors.forename: Jin Ling
authors.initials: JL
authors.lastname: Li
authors.forename: Si Yuan
authors.initials: SY
authors.lastname: Li
authors.forename: Bi Dan
authors.initials: BD
authors.lastname: Zhu
authors.forename: He
authors.initials: H
authors.lastname: Li
authors.forename: Zhou
authors.initials: Z
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000550:Amblyopia / Q000453:epidemiology*; D002648:Child; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D015995:Prevalence; D012029:Refraction, Ocular / Q000502:physiology; D013285:Strabismus / Q000453:epidemiology*; D013334:Students / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D014792:Visual Acuity / Q000502:physiology
keywords: Amblyopia; children; epidemiology; prevalence; strabismus