Aims: to estimate the prevalence of visual impairment and blindness; to identify the major causes of visual impairment and blindness and to estimate their overall impact, particularly on cataracts.
Methods: We used a population-based method. A cluster sample was selected, with the number of households randomly selected from a community depending on the size of the population. Examinations and data collection were carried out using the procedures recommended by the WHO.
Results: We included 3,981 individuals, 3,547 of whom were given a medical examination (89% participation). The structure of the sample differed from that of the Tunisian population, with people over the age of 60 years over represented in the sample. The crude prevalence of blindness was 1.2% (adjusted prevalence 0.8%) and that for bilateral visual impairment was 3% (adjusted prevalence 2%). There were 225,000 individuals with severely impaired vision, of whom 64,500 were blind (including 2,100 children under the age of 15 years) and 160,000 were visually impaired (including 8,700 children). Individuals over the age of 60 were eight times more likely to become blind and 6.7 times more likely to suffer visual impairment than those below the age of 60. Cataracts, particularly associated with aging, were the main cause of blindness (66%) and bilateral visual impairment (54.6%). Uncorrected aphakia accounted for a significant fraction of the visual deficiencies identified in this survey (6.4% of cases of blindness and 11.8% of cases of bilateral visual impairment). 1.7% of the individuals examined (135,000 people) had ocular surgery and 80,000 had undergone surgery for cataracts. Only 41% of those individuals who had cataracts had undergone surgery. The provision of cataract surgery was therefore inadequate.
Conclusion: About 80% of the cases of blindness registered were preventable or treatable. The development of appropriate strategies for dealing with cataract blindness should significantly reduce the incidence of blindness.