Prevalence and Causes of Visual Impairment and Blindness in Older Adults from Urban Areas of Parintins City: The Brazilian Amazon Region Eye Survey

Abstract

Purpose: The Brazilian Amazon Region Eye Survey (BARES) is a population-based prevalence study of visual impairment, blindness and ocular diseases in adults aged 45 years and older from urban and rural areas of Parintins city, Brazil. Our purpose is to describe the prevalence and causes of visual impairment and blindness in the urban population from this ongoing epidemiologic study.

Methods: A random selection of census sector clusters was used to identify a population sample in urban and rural areas. Eligible subjects 45 years of age and older in the 14 selected urban clusters were enumerated through a door-to-door household survey and invited to an examination site for visual acuity testing and eye examinations. The principal cause of reduced central vision was identified for eyes with presenting visual acuity worse than 20/32.

Results: A total of 1410 eligible persons in 1319 households were enumerated, and 1180 (83.7%) were examined. The prevalence of presenting visual acuity≥20/32 in both eyes was 64.4% (95% confidence interval [CI]:61.5% - 67.2%), and 83.7% (95% CI: 80.9% - 86.1%) with best correction. The prevalence of presenting mild visual impairment - MVI (<20/32 - ≥ 20/63) in the better eye was 16.5% (95% CI: 13.8% -19.6%), and 8.3% (95% CI: 6.5% - 10.4%) with best correction. The prevalence of presenting visual impairment - VI (<20/63 - ≥20/200) was 15.2% (95% CI: 12.8% - 18.0%), and 5.4% (95% CI: 4.1% - 7.2%) with best correction. The prevalence of presenting bilateral blindness (<20/200 in both eyes) was 3.8% (95% CI: 2.8% - 5.2%), and 2.7% (95% CI: 1.7% - 4.3%) with best correction. Presenting and best corrected blindness were associated with older age and low schooling. Cataract (40.1%), disorganized/absent globe (10.2%) and glaucoma (9.6%) were the most common causes of blind eyes. The main causes of eyes with VI and MVI were: uncorrected refractive errors (VI - 42.9%; MVI - 76.7%), cataract (VI - 40.8%; MVI - 14.4%) and pterygium (VI - 5.1%; MVI - 3.3%).

Conclusions: Blindness, particularly due to cataract is a significant problem among this urban population in the Brazilian Amazon Region. Prevention of blindness programs to an increasing number of elderly people, with emphasis on improving access to cataract surgical services, must be implemented.