Prevalence of refractive errors in a Brazilian population: the Botucatu eye study.
OBJECTIVE
To determine the prevalence and demographic associations of refractive error in Botucatu, Brazil.


METHODS
A population-based, cross-sectional prevalence study was conducted, which involved random, household cluster sampling of an urban Brazilian population in Botucatu. There were 3000 individuals aged 1 to 91 years (mean 38.3) who were eligible to participate in the study. Refractive error measurements were obtained by objective refraction.


RESULTS
Objective refractive error examinations were performed on 2454 residents within this sample (81.8% of eligible participants). The mean age was 38 years (standard deviation (SD) 20.8 years, Range 1 to 91) and females comprised 57.5% of the study population. Myopia (spherical equivalent (SE) < -0.5 dropters (D)) was most prevalent among those aged 30-39 years (29.7%; 95% confidence interval (CI) 24.8-35.1) and least prevalent among children under 10 years (3.8%; 95% confidence interval (CI) 1.6-7.3). Conversely hypermetropia (SE > 0.5D) was most prevalent among participants under 10 years (86.9%; 95% CI 81.6-91.1) and least prevalent in the fourth decade (32.5%; 95% CI 28.2-37.0). Participants aged 70 years or older bore the largest burden of astigmatism (cylinder at least -0.5D) and anisometropia (difference in SE of > 0.5D) with a prevalence of 71.7% (95% CI 64.8-78.0) 55.0% (95% CI 47.6-62.2) respectively. Myopia and hypermetropia were significantly associated with age in a bimodal manner (P < 0.001), whereas anisometropia and astigmatism increased in line with age (P < 0.001). Multivariate modeling confirmed age-related risk factors for refractive error and revealed several gender, occupation and ethnic-related risk factors.


CONCLUSIONS
These results represent previously unreported data on refractive error within this Brazilian population. They signal a need to continue to screen for refractive error within this population and to ensure that people have adequate access to optical correction.
Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, Sao Paulo State, Sao Paulo, Brazil.
Silvana Artioli
SA
Schellini
Shane R
SR
Durkin
Erika
E
Hoyama
Flavio
F
Hirai
Ricardo
R
Cordeiro
Robert J
RJ
Casson
Dinesh
D
Selva
Carlos Roberto
CR
Padovani
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D006801:Humans; D007223:Infant; D008875:Middle Aged; D015995:Prevalence; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000453:epidemiology*; D017678:Sex Distribution; D014505:Urban Population / Q000706:statistics & numerical data*; D014786:Vision Disorders / Q000453:epidemiology*; D014792:Visual Acuity; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*; D055815:Young Adult