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Lisandro Sakata, Viviane Mayumi Sakata, Ana L Rocha, Gustavo Sakuno, Andre Mozena, Patricia Watanabi, Thais Nakayama, Mario Sato, Ana Tereza R Moreira, Kenji Sakata; Prevalence and Causes of Visual Impairment and Blindness in an Urban Population: The South Brazilian Bocaiuva Study. Invest. Ophthalmol. Vis. Sci. 2014;55(13):6080.
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© ARVO (1962-2015); The Authors (2016-present)
To describe the prevalence and causes of visual impairment and blindness in an urban Brazilian population.
All subjects over 40 years old living in the urban part of Bocaiuva city were selected and invited to participate in this population-based study. Participants underwent standardized ophthalmic assessments for visual impairment and blindness, using best-corrected visual acuity (BCVA), and presenting visual acuity (PVA), according to the modified World Health Organization (WHO) definitions. Unilateral blindness was defined based on the worse eye, and bilateral visual impairment or blindness was defined on the basis of the better eye. Visual impairment was defined as VA <20/60 but ≥ 20/400, and blindness was defined as VA < 20/400. Primary causes of visual impairment and blindness were determined.
A total of 1211 eligible individuals (78.6% response rate) participated, whereas 791 (65.3%) self-reported as White, and 385 (31.8%) as non-White. On the basis of WHO definitions, the age-standardized prevalence was 1.78% for bilateral blindness, 2.16% for bilateral visual impairment, and 3.14% for unilateral blindness. Another 0.17% of bilateral blindness and 3.15% of visual impairment were correctable with refraction. Cataract was the principal cause of best-corrected bilateral blindness (45.4%) and bilateral visual impairment (55.5%). Other major causes of bilateral blindness were: retina/macula abnormalities - including uveitis (31.8%), glaucoma (18.2%), and diabetic retinopathy (4.5%). Other major causes for visual impairment were: retina/macula abnormalities - including uveitis (22.2%), and diabetic retinopathy (3.7%). The main causes for unilateral blindness were: trauma (35.1%), and cataract (21.6%).
This is first population-based study from Brazil to report the rates of best-corrected bilateral blindness, visual impairment, and unilateral blindness. Predominant causes of blindness and visual impairment are treatable.
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