title: Prevalence and causes of visual impairment in low-middle income school children in Sao Paulo, Brazil.
abstract: OBJECTIVE
  Assess prevalence and causes of vision impairment among low-middle income school children in São Paulo.
  
  
  METHODS
  Cluster sampling was used to obtain a random sample of children ages 11 to 14 years from public schools (grades 5-8) in three districts from June to November 2005. The examination included visual acuity testing, ocular motility, and examination of the external eye, anterior segment, and media. Cycloplegic refraction and fundus examination were performed in children with uncorrected visual acuity 20/40 or worse in either eye. A principal cause of visual impairment was determined for eyes with uncorrected visual acuity of 20/40 or worse.
  
  
  RESULTS
  A total of 2825 children were enumerated and 2441 (86.4%) were examined. The prevalence of uncorrected, presenting, and best-corrected visual acuity 20/40 or worse in the better eye was 4.82%, 2.67%, and 0.41%, respectively. Spectacles were used by 144 (5.9%) children. Refractive error was a cause in 76.8% of children with visual impairment in one or both eyes; amblyopia, 11.4%; retinal disorders, 5.9%; other causes, 2.7%; and unexplained causes, 7.7%. Myopic visual impairment (spherical equivalent -0.50 D in one or both eyes) was not associated with age or grade level, but female sex was marginally significant (P = 0.070). Hyperopic visual impairment (+2.00 D or more) was not associated with age, grade level, or sex.
  
  
  CONCLUSIONS
  The prevalence of reduced vision in low-middle income urban São Paulo school children was low, most of it because of uncorrected refractive error. Cost-effective strategies are needed to address this easily treated cause of vision impairment.
authors.affiliation: Department of Ophthalmology, Federal University of São Paulo, Paulista School of Medicine, São Paulo, Brazil. ssalomao@oftalmo.epm.br
authors.forename: Solange R
authors.initials: SR
authors.lastname: Salomão
authors.forename: Rafael W
authors.initials: RW
authors.lastname: Cinoto
authors.forename: Adriana
authors.initials: A
authors.lastname: Berezovsky
authors.forename: Luana
authors.initials: L
authors.lastname: Mendieta
authors.forename: Célia R
authors.initials: CR
authors.lastname: Nakanami
authors.forename: César
authors.initials: C
authors.lastname: Lipener
authors.forename: Emílio de Haro
authors.initials: Ede H
authors.lastname: Muñoz
authors.forename: Fabio
authors.initials: F
authors.lastname: Ejzenbaum
authors.forename: Rubens
authors.initials: R
authors.lastname: Belfort
authors.forename: Gopal P
authors.initials: GP
authors.lastname: Pokharel
authors.forename: Leon B
authors.initials: LB
authors.lastname: Ellwein
mesh_terms: D000293:Adolescent; D001938:Brazil / Q000453:epidemiology; D002648:Child; D005133:Eye Movements; D005139:Eyeglasses / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D012030:Refractive Errors / Q000150:complications / Q000453:epidemiology*; D012923:Social Class; D014786:Vision Disorders / Q000453:epidemiology* / Q000209:etiology; D014787:Vision Tests; D014792:Visual Acuity; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*