The Brazilian Amazon Region Eye Survey: Design and Methods

Purpose: To describe the study design, operational strategies, procedures, and baseline characteristics of the Brazilian Amazon Region Eye Survey (BARES), a population-based survey of the prevalence and causes of distance and near visual impairment and blindness in older adults residing in the city of Parintins. Methods: Cluster sampling, based on geographically defined census sectors, was used for cross-sectional random sampling of persons 45 years and older from urban and rural areas. Subjects were enumerated through a door-to-door survey and invited for measurement of uncorrected, presenting and best-corrected visual acuity and an ocular examination. Results: Of 9931 residents (5878 urban and 4053 rural), 2384 individuals (1410 urban and 974 rural) were eligible and 2041 (1180 urban and 861 rural) had a clinical examination (response rate 85.6%). The majority of participants were female (1041, 51.0%); the average age was 59.9 +/- 11.1 years (60.2 +/- 11.2 years for urban and 59.4 +/- 11.1 years for rural); 1360 (66.6%) had primary schooling or less (58.1% in urban and 78.4% in rural) and 57.8% were resident in urban areas. The age distribution between sexes was similar (p = 0.178). Both sex and age distributions of the sample were comparable to that of the Brazilian Amazon Region population. Conclusions: The BARES cohort will provide information about the prevalence and causes of near and distance vision in this underprivileged and remote population in Brazil.