Ocular disorders causing blindness in working-age outpatients: a prospective study at the African Institute of Tropical Ophthalmology (IOTA, Bamako, Mali)

The objective of this study was to determine the different groups of ocular disorders causing low vision or blindness among working-age patients consulting at the African Institute of Tropical Ophthalmology (IOTA) in Bamako, Mali. This prospective study took place from 1 February through 8 April, 2003, at IOTA. It included all new patients aged between 18 and 50 years, regardless of whether they worked, but excluding students. 828 patients were recruited: 384 men (46.4%) and 444 women (53.6%). The average age was 35.7 years. The rate of bilateral blindness was 5.8%, of low vision 8.5%, and of blindness in one eye 11.5%. Men and women did not differ significantly in rates of bilateral blindness (p = 0.77) or low vision (p = 0.24), but blindness in a single eye affected men (67.4%) more often than women (32.6%, p = 0.01). While the frequency of bilateral blindness and low vision increased with age, blindness in one eye affected all ages. We observed no significant differences according to ethnic group in the prevalence of bilateral blindness and low vision, both observed most frequently among housewives, farmers and low-income workers, most illiterate. The major causes of bilateral blindness were cataracts 29.2%, glaucoma 22.9%, trachoma 14.6%, ocular manifestations linked to HIV/AIDS 8.3%, and non-glaucomatous optical neuropathies 8.3%. Half the cases (50.5%) of blindness in one eye resulted from ocular trauma, and five cases from HIV/AIDS (5.3%). Low vision resulted from impaired refraction 22.9%, cataract 17.2%, trachoma 15.7%, glaucoma 10% and corneal opacities 5.7%. The high rate of blindness and low vision are associated with the study site: a reference center whose population was composed completely of patients with vision problems. The causes of blindness and low vision have not changed over time except for the ocular manifestations of HIV/AIDS, which is among the most important current causes of blindness, because of the lack of antiretroviral treatments in sub-Saharan Africa. If nothing stops this pandemic, it will soon modify epidemiological data about blindness. Blindness and visual deficiencies, already a public health problem, will become an important socioeconomic burden in sub-Saharan Africa and may even stop progress among low-income countries.