Study Design and Methods for a Population-based Study on the Prevalence and Causes of Distance and Near Vision Impairment and Blindness in Parintins City: The Brazilian Amazon Region Eye Survey (BARES)

Abstract

Purpose : To describe the study design, operational strategies, procedures, and baseline characteristics of the Brazilian Amazon Region Eye Survey (BARES), a population-based assessment of the prevalence and causes of distance and near visual impairment/blindness in older adults.

Methods : BARES is a population-based cross-sectional prospective study conducted from March 2014 to May 2015 in four visits to Parintins city. Participants were residents 45 years and older from 14 urban and 6 rural randomly selected clusters. A door-to-door interview was performed and household residents were listed along with information on their age, gender and shooling. Eligible participants were invited for an eye examination including distance and near visual acuity, automated and subjective refraction, intraocular pressure, detailed anterior and posterior segment examination with emphasis on previous cataract surgery and its possible complications, spectral domain ocular coherence tomography, photography of anterior and posterior segment. Rural residents were tested with portable equipment available in a clinical basis assembled on a boat to allow access to those living on the margins of the river. Information on glasses usage, previous cataract surgery, self-reported diabetes and fundoscopy in the last year were taken from each participant. Free-of-charge treatment was provided (glasses, surgery etc).

Results : Out of 9930 (5878 urban and 4052 rural) residents, 2383 (1410 urban and 973 rural) were eligible and 2042 (1180 urban and 862 rural) had a clinical examination (response rate of 85.7%). The majority of participants 1036 were female (50.7%); the average (standard deviation) age was 59.9 (11.2) years (60.2±11.2 for urban and 59.5±11.1 for rural); 1357 (66.5%) had primary schooling or less (57.8% in urban and 78.3% in rural) and 57.8% were residents of urban areas. The age distribution between genders was similar (p=0.178). Both gender and age distributions of the current sample were comparable to that of the Brazilian Amazon Region.

Conclusions : BARES has recruited Brazilian Amazonians 45 and older for an ophthalmic epidemiologic study. The BARES cohort will provide information about the prevalence and causes of near and distance vision impairment/blindness in this underprivileged and remote population in Brazil.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.