Optic neuropathy endemic in secondary school children in Dar es Salaam, Tanzania

Aim: To investigate the prevalence and causes of optic neuropathy, reported as epidemic in 1997, among secondary school students in Dar es Salaam, Tanzania. Patients and methods: First year students (n = 10 892) from 63 secondary schools located within 30 km from the base hospital were interviewed and had a visual acuity (VA) screening test. Students failing the 6/12-line in either eye were defined as having "poor eyesight" and referred to the base hospital where an optometrist retested VA and refracted them. An ophthalmologist examined students with VA of 6/12 or worse in either eye and visual impairment was defined as VA of worse than 6/12 with best correction. Associations between optic neuropathy, socioeconomic status and educational results were investigated. Results: Students' ages ranged from 12 to 22 (mean 15.2) years; 50.6% were male. The prevalence of optic neuropathy was 0.3 (SD 0.051)%. The condition affected older students and was associated with the family having fewer economic possessions (car, computer, television). Optic neuropathy accounted for 19/33 (58%) of bilateral visual impairment cases. No effect of the disease on educational performance was identified. Conclusion: Optic neuropathy remains a significant problem in this population and can now be termed endemic rather than epidemic. Further research into its causes is required.