title: The prevalence of amblyopia in 7-year-old schoolchildren in Iran.
abstract: OBJECTIVE
  To determine the prevalence of amblyopia in schoolchildren aged 7 years in Iran, its relation with refractive errors, and its determinants.
  
  
  METHODS
  In this cross-sectional study, cluster sampling was done from elementary school students in 7 cities in Iran. In all schools, an optometrist conducted all tests, including measurement of uncorrected and corrected visual acuity, cycloplegic refraction, and cover test. In this study, amblyopia was defined as best corrected visual acuity 20/30 or less or a 2-line interocular optotype acuity difference with no pathology.
  
  
  RESULTS
  Of the 4157 students selected for the study, 3675 participated and final analyses were done with data from 3547 children. The prevalence of amblyopia was 1.88% (95% CI: 1.24-2.52) (n=63). The prevalence was 1.91% (95% CI: 0.85-2.97) in boys and 1.85% (95% CI: 1.12-2.58) in girls (p=0.92). Among these cases, 60.30% (n=38) were unilateral. Also, 61.9% were strabismic, 27.0% were anisometropic, 9.5% were isometropic, and one case (1.6%) was due to congenital cataracts. Amblyopic individuals were more hypermetropic and the mean cylinder error was significantly higher.
  
  
  CONCLUSIONS
  Necessary attention should be paid to amblyopia, although its prevalence in Iran is mid-range when compared with other countries. Amblyopia is more common in hyperopic and astigmatic individuals and therefore it is important to pay more attention to this refractive error during childhood. Since strabismus is the most common cause of amblyopia in Iran, children need to be checked for strabismus before the age of 5 years.
authors.affiliation: Noor Ophthalmology Research Center, Noor Eye Hospital , Tehran , Iran .
authors.forename: Hassan
authors.initials: H
authors.lastname: Hashemi
authors.forename: Abbasali
authors.initials: A
authors.lastname: Yekta
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Jafarzadehpur
authors.forename: Fereidon
authors.initials: F
authors.lastname: Nirouzad
authors.forename: Hadi
authors.initials: H
authors.lastname: Ostadimoghaddam
authors.forename: Babak
authors.initials: B
authors.lastname: Eshrati
authors.forename: Saman
authors.initials: S
authors.lastname: Mohazzab-Torabi
authors.forename: Mehdi
authors.initials: M
authors.lastname: Khabazkhoob
mesh_terms: D000550:Amblyopia / Q000175:diagnosis / Q000453:epidemiology*; D015858:Anisometropia / Q000453:epidemiology; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D015995:Prevalence; D012030:Refractive Errors / Q000453:epidemiology; D013285:Strabismus / Q000453:epidemiology; D014792:Visual Acuity / Q000502:physiology
keywords: Amblyopia; Iran; cross-sectional-study; middle-east; prevalence