Prevalence and causes of visual impairment in low-middle income school children in Sao Paulo, Brazil.

PURPOSE: 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.

Prevalence and causes of vision impairment and blindness in older adults in Brazil: the Sao Paulo Eye Study.

PURPOSE: Investigate prevalence and causes of vision impairment/blindness in older adults in a low-middle income area of Sao Paulo, Brazil. METHODS: Cluster sampling, based on geographically defined census sectors, was used in randomly selecting cross-sectionally persons 50 years of age or older. Subjects were enumerated through a door-to-door survey and invited for measurement of presenting and best-corrected visual acuity and an ocular examination. The principal cause was identified for eyes with presenting visual acuity less than 20/32. RESULTS: A total of 4,224 eligible persons in 2,870 households were enumerated, and 3,678 (87.1%) examined. The prevalence of presenting visual acuity > or = 20/32 in both eyes was 61.6% (95% confidence interval [CI]: 59.4%-63.9%), and 80.4% (95% CI: 78.8%-82.1%) with best correction. The prevalence of visual impairment (< 20/63 to > or =20/200) in the better eye was 4.74% (95% CI: 3.97%-5.53%), and 2.00% (95% CI: 1.52%-2.49%) with best correction. The prevalence of presenting bilateral blindness (< 20/200) was 1.51% (95% CI: 1.20%-1.82%), and 1.07% (95% CI: 0.79%-1.35%) with best correction. Presenting blindness was associated with older age and lack of schooling. Retinal disorders (35.3%) and cataract (28.3%) were the most common causes of blind eyes. Cataract (33.2%), refractive error (32.3%), and retinal disorders (20.3%) were the main causes of vision impairment < 20/63 to > or = 20/200, with refractive error (76.8%) and cataract (12.2%) as main causes for eyes with acuity < 20/32 to > or = 20/63. CONCLUSIONS: Vision impairment is a significant problem in older Brazilians reinforcing the need to implement prevention of blindness programs for elderly people with emphasis on those without schooling.