title: Amblyopia and strabismus in Iranian schoolchildren, Mashhad.
abstract: OBJECTIVE
  To determine the prevalence of amblyopia and strabismus among the population of schoolchildren Mashhad, Iran.
  
  
  METHODS
  In a cross-sectional study with cluster sampling, 2510 schoolchildren were selected from schools of district 1 in Mashhad. Uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were recorded for each participant. Amblyopia was distinguished as a reduction of BCVA to 20/30 or less in one eye or 2-line interocular optotype acuity differences in the absence of pathological causes.
  
  
  RESULTS
  Of the 2510 selected schoolchildren, 2150 participated (response rate, 85.6%). The mean (± standard deviation) age of the participants was 13.2 ± 3.2 (range, 6-21) years. The prevalence of amblyopia was 1.9% (95% CI: 0.94-2.90); 2.1% (95% CI: 0.10-3.16) in girls and 1.7% (95% CI: 0.30-3.12) in boys (P = 0.6). Among myopic, hyperopic, and astigmatic students, 3.7%, 27.8%, and 6.5% had amblyopia, respectively (P<0.001). The causes of amblyopia were anisometropia in 65.9%, strabismus in 24.4%, and isoametropia in 9.8%. The prevalence of strabismus was 3.1% (95% CI, 1.3% to 4.3%); 4.2% (95% CI, 3.05 to 5.7%) in girls, and 2.0% (1.3% to 2.9%) in boys (P = 0.0011). Strabismus was significantly more prevalent among hyperopic students (7.9%) compared with myopic ones (3.7%).
  
  
  CONCLUSIONS
  Results of the present study indicate that the prevalence rate of amblyopia was in the mid-range of other studies, and the prevalence of strabismus was relatively high. Since refractive errors, especially hyperopia, are responsible for some cases of strabismus.
authors: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors: Mohammad
authors: M
authors: Faghihi
authors: Hadi
authors: H
authors: Ostadimoghaddam
authors: Abbas Ali
authors: AA
authors: Yekta
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D000550:Amblyopia / Q000453:epidemiology*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D015995:Prevalence; D012574:Schools; D017678:Sex Distribution; D013285:Strabismus / Q000453:epidemiology*; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult