Visual impairment and myopia in Brazilian children: a population-based study.
OBJECTIVE
To determine the frequency of myopia and other causes of visual impairment (VI) in individuals aged 10 to 15 years who live in a typical Brazilian city.


METHODS
Random selection of geographically based clusters was performed to obtain a sample of children aged 10 to 15 years in Gurupi City, Tocantins, Brazil. From June to August 2007, children in 12 clusters were enumerated through a door-to-door survey. All children with an uncorrected visual acuity (VA) worse than 20/32 in either eye were scheduled for ophthalmologic evaluation, including VA and ocular motility testing, cycloplegic refraction, and external, biomicroscopic, and dilated funduscopic examinations. The primary cause of VI was determined for eyes with an uncorrected VA of 20/40 or worse.


RESULTS
A total of 1590 children were examined; 814 (51%) were boys and 776 (49%) were girls. The prevalence of uncorrected, presenting and best-corrected VA of 20/40 or worse in the better eye was 5.72%, 2.83%, and 0.81%, respectively. The primary cause of VI in one or both eyes was refractive error in 65 (89%) of 73 children, amblyopia in 4 (5.5%) of 73 children, retinal disorders in 3 (4.1%) of 73 children, and congenital cataracts in 1 (1.4%) of 73 children. In this population, the prevalence of VI-related myopia was 3.14%.


CONCLUSIONS
The prevalence of VI among children aged 10 to 15 years in this typical Brazilian city is low and similar to other school-based studies, and most of the VI is caused by uncorrected myopia.
Department of Ophthalmology, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
Fuad
F
Moraes Ibrahim
Marlon
M
Moraes Ibrahim
Juliana Rosa
JR
Pomepo de Camargo
Maria de Lourdes
Mde L
Veronese Rodrigues
Ingrid U
IU
Scott
Jayter
J
Silva Paula
D000293:Adolescent; D017677:Age Distribution; D001938:Brazil / Q000453:epidemiology; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D011159:Population Surveillance / Q000379:methods*; D015995:Prevalence; D012189:Retrospective Studies; D017678:Sex Distribution; D014787:Vision Tests; D015354:Vision, Low / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D014792:Visual Acuity; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*