Abstract
Purpose :
Vision loss caused by corneal opacity was the most common cause of blindness and visual impairment in central Tanzania twenty years ago, when trachoma was hyper-endemic. Prevalence of trachoma has significantly decreased over recent years, therefore, we performed a cross-sectional study to measure the prevalence and attributable causes of bilateral and unilateral visual impairment and blindness in Kongwa district in central Tanzania, and to compare the results with studies from different areas in Africa and from the study that was performed in central Tanzania in 1986.
Methods :
We examined the visual acuity in randomly selected population aged 15 and over. Visual acuity of <20/63 but ≥20/200 was defined as visual impairment, and <20/200 was defined as blindness. All subjects with unilateral or bilateral visual acuity of <20/63 were examined to determine the causes of their visual impairment or blindness, which were classified as corneal, cataract, absence of the eye or phthisical eye, and “others” including unidentified or unmeasured causes.
Results :
851 subjects participated in the study from 1248 eligible people (response rate= 68.2%). The prevalence of unilateral visual impairment, including unilateral blindness, was 8.8% (95% confidence interval (CI)=7.0%-10.9%). The prevalence of bilateral visual impairment including bilateral blindness was 2.5% (95% CI=1.5%-3.8%). The prevalence of bilateral blindness alone was 0.59%. Cataract was the most common cause of bilateral visual impairment (48%), while corneal damage was the most common cause of unilateral visual impairment (31%)
Conclusions :
Our study found an evidence of improvement in bilateral visual impairment in central Tanzania, mainly in the younger age groups, compared to 1986 study. The overall prevalence and causes of visual loss still suggest unmet needs for cataract and preventive eye care services in central Tanzania similar to other parts in Africa. As the current population ages, it is likely that corneal opacity due to trachoma as a cause of blindness and visual loss will continue to decline.
This is a 2020 ARVO Annual Meeting abstract.