Prevalence of amblyopia and strabismus in a population of 7th-grade junior high school students in Central China: the Anyang Childhood Eye Study (ACES)

Ophthalmic Epidemiol. 2014 Jun;21(3):197-203. doi: 10.3109/09286586.2014.904371. Epub 2014 Apr 17.


Purpose: 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.

Conclusion: 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.

Keywords: Amblyopia; children; epidemiology; prevalence; strabismus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Amblyopia / epidemiology*
  • Child
  • China / epidemiology
  • Cluster Analysis
  • Cross-Sectional Studies
  • Female
  • Health Surveys
  • Humans
  • Male
  • Prevalence
  • Refraction, Ocular / physiology
  • Strabismus / epidemiology*
  • Students / statistics & numerical data
  • Surveys and Questionnaires
  • Visual Acuity / physiology