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

Abstract

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:10,892 first year students from 63 secondary schools within 30km from the base hospital were interviewed and had a visual acuity 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 re-tested visual acuity and refracted them. An ophthalmologist examined students with visual acuities of 6/12 or worse in either eye and visual impairment was defined as VA ofworse than 6/12 with best correction. Associations between optic neuropathy, socioeconomic status and educational results were investigated. Results:Students ages ranged from 12-22 years , mean 15.2 years and 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,TV). 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.

Epidemic Optic Neuropathy Is Evident in the Somalian Population

“…Given their similarity to the Cuban epidemic (7,8), and their shared clinical features with Leber herditary optic neuropathy (14), it seems likely that both the Somalian and Tanzanian optic neuropathies are disorders resulting from mitochondrial dysfunction. This has already been proposed for the Cuban epidemic (7)(8)(9)(10)(11)(12)(13)(14)(15).…”

“…If epidemic optic neuropathy is associated with nutritional deficiencies, the increased demands of pregnancy followed by lactation might also be a contributing factor. With optic neuropathy in Tanzania now classed as endemic (9), and evidence presented here for the first time of its prevalence in Somalia, more effective treatment strategies are required. Current treatment of Bvitamin supplementation based on its use in the Cuban epidemic (7,8) has proven very successful in acute cases in Tanzania (Dalmar et al, unpublished data, 2010), and the large extent of visual loss reported over the first month in Somalia places emphasis on the need for early diagnosis and treatment through Training community eye care workers.…”

“…Widespread B-vitamin supplementation largely resolved the outbreak (7). The clinical features of the Cuban epidemic closely resemble an outbreak in Tanzania, which was first reported in 1988 and is now more appropriately regarded as endemic in the secondary school population in Dar es Salaam (9). Reports from Tanzania (10,11) described bilateral, simultaneous, usually painless, visual failure over 2-12 weeks, loss of nerve fibers in the papillomacular bundle associated with central or cecocentral scotomas, impaired color vision, and peripheral neuropathy.…”

Optic Neuropathy among a Prison Population in Papua New Guinea

“…[1][2][3][4][5][6][7] These share some commonalities with a 1991-1993 ON epidemic in Cuba. 8 Such ON is typically characterized by progressive bilateral vision loss (although not necessarily symmetrical), with impaired color perception, visual field scotomata and optic nerve head (ONH) pallor.…”

Low Prevalence of Bilateral (Presumed Nutritional) Optic Neuropathy as a Cause of Blindness in The Gambia

“…First reported in 1988, the most recent epidemic, also occurred in Tanzania, appeared to be endemic within the secondary school population of Dar es Salaam (7). Patients presented with bilateral, simultaneous, usually painless, visual loss over 2-12 weeks and were found to have impaired color vision, central or cecocentral scotomas, and, in many cases, peripheral neuropathy (8)(9)(10).…”