Prevalence and causes of blindness: Results from the rapid assessment of avoidable blindness survey in gezira state, sudan

Abstract

Objectives: To estimate the prevalence of avoidable blindness in people aged 50 years and older in Gezira state, Sudan, using the Rapid Assessment for Avoidable Blindness methodology. Design: Cross-sectional, population-based survey. Participants: Forty-three clusters of 50 people aged 50 years or older were selected by probability proportionate to size sampling of clusters. Households within clusters were selected through compact segment sampling. A total of 2150 eligible persons were selected, of whom 2103 (97.8%) persons were examined. Materials and Methods: Participants underwent a comprehensive ophthalmic examination in their homes by specially trained ophthalmic teams, including measurement of visual acuity (VA) with a tumbling-E chart and the diagnosis of the principal cause of visual impairment. Results: The prevalence of bilateral blindness (presenting VA <3/60) was 9.37% (95% confidence interval [CI] ±1.95) and the prevalence of bilateral visual impairment (VA of <6/18-6/60) was 3.9% (95% CI ±1.10) in the sample. Definite avoidable causes of blindness (i.e., cataract, refractive error, trachoma and corneal scarring) were responsible for 74.6% of bilateral blindness. Cataract was the major cause of blindness (57.4%), followed by glaucoma (17.3%). Conclusions: The prevalence of blindness in people aged 50 years and older in Gezira state was slightly higher than that expected. Than main cause of blindness was cataract, followed by glaucoma. Three quarters of blindness was due to avoidable causes.