title: Prevalence of refractive errors among schoolchildren in Shiraz, Iran.
abstract: OBJECTIVE
  To determine the prevalence of refractive errors in Shiraz schoolchildren by age and gender.
  
  
  METHODS
  For this cross-sectional study, random cluster sampling was carried out from students of the 2008-2009 academic year. After the initial interview, ophthalmic examinations including tests of visual acuity, non-cycloplegic and cycloplegic refraction and binocular vision were performed. Myopia was defined as a spherical equivalent < or =-0.50 dioptre (D), hyperopia as > or =+2.0 D, and astigmatism as a cylinder refraction > or =0.75 D. All values for school grade and gender were directly standardized based on the total student population in the 2008-2009 school year.
  
  
  RESULTS
  A total of 2130 students were sampled, of which 1872 participated in the study (response rate = 87.88%). The prevalence of uncorrected, best-corrected, presenting and spectacle corrected visual acuity of 6/12 or worse in the better eye was 6.46%, 0%, 1.49% and 0.9%, respectively. The prevalence rates of myopia, hyperopia and astigmatism were 4.35% (95% confidence interval [CI]: 2.89-5.82%), 5.04% (95% CI: 3.50-6.58%), and 11.27% (95% CI: 9.81-12.74%), respectively. Anisometropia was detected in 2.58% of schoolchildren. The prevalence of hyperopia significantly decreased with age (P = 0.021).
  
  
  CONCLUSIONS
  Compared with other reported rates, the prevalence of myopia in the schoolchildren of Shiraz is similar to that in most places excluding East Asian countries, and that of hyperopia is in the mid range.
authors.affiliation: Department of Optometry, Mashhad University of Medical Sciences, Mashhad, Vali'asr Ave, Tehran 19686, Iran.
authors.forename: Abbasali
authors.initials: A
authors.lastname: Yekta
authors.forename: Akbar
authors.initials: A
authors.lastname: Fotouhi
authors.forename: Hassan
authors.initials: H
authors.lastname: Hashemi
authors.forename: Cirous
authors.initials: C
authors.lastname: Dehghani
authors.forename: Hadi
authors.initials: H
authors.lastname: Ostadimoghaddam
authors.forename: Javad
authors.initials: J
authors.lastname: Heravian
authors.forename: Akbar
authors.initials: A
authors.lastname: Derakhshan
authors.forename: Reihaneh
authors.initials: R
authors.lastname: Yekta
authors.forename: Mehdi
authors.initials: M
authors.lastname: Behnia
authors.forename: Mehdi
authors.initials: M
authors.lastname: Khabazkhoob
mesh_terms: D000293:Adolescent; D015858:Anisometropia / Q000601:surgery; D001251:Astigmatism / Q000453:epidemiology / Q000601:surgery; D002648:Child; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000453:epidemiology / Q000601:surgery; D007492:Iran / Q000453:epidemiology; D008297:Male; D009216:Myopia / Q000453:epidemiology / Q000601:surgery; D015995:Prevalence; D012030:Refractive Errors / Q000453:epidemiology*; D014792:Visual Acuity