Rapid assessment of avoidable blindness and cataract surgical services in kilimanjaro region, Tanzania

Abstract

Purpose: To estimate the prevalence and causes of avoidable blindness and visual impairment in persons 50 years of age and older, and to assess the impact of cataract surgical services.

Methods: In this cross-sectional population-based survey, 72 clusters of 50 people 50 years and older were selected by probability proportionate to size sampling. Households within clusters were selected through compact segment sampling. Participants underwent an ophthalmic examination in their homes, including measurement of visual acuity (VA) with a tumbling-E chart and diagnosis of the principal cause of visual impairment. Patients who had been operated on were questioned about details of their cataract surgery.

Results: Three thousand six hundred eligible subjects were selected, of whom 3,436 (95.5%) were examined. The prevalence of bilateral blindness (presenting VA < 3/60) was 2.4% (95% confidence interval [CI], 1.9%-2.9%); prevalence of severe visual impairment was 0.99% (95% CI, 0.98%-0.99%); and prevalence of visual impairment (VA of < 6/18 and > or = 6/60) was 5.4% (95% CI, 4.6%-6.2%) in the sample. Unoperated cataract accounted for 52.4% of blindness and 70.6% of severe visual impairment. Cataract surgical coverage among people at 3/60 was 68.9%. Overall, 58.6% and 69.6% of the 191 eyes that had undergone cataract surgery had VA greater than or equal to 6/18 with available correction and best correction respectively.

Conclusions: The prevalence of blindness in this population in Kilimanjaro Region was low, reflecting high cataract surgical coverage from an outreach program. Even with high cataract surgical coverage, cataract remains the leading cause of vision loss and an emphasis on quality is needed.