Visual phenotype of multiple sclerosis in the Afro-Caribbean population and the influence of migration to metropolitan France.

ABSTRACT

PURPOSE: To describe the visual phenotype of multiple sclerosis (MS) in the Afro-Caribbean population living in Martinique (French West Indies) and to specify the influence of the migration to metropolitan France on ocular impairment. DESIGN: Prospective consecutive observational case series. METHODS: A complete ophthalmologic examination was performed. PARTICIPANTS: A total of 112 patients of Afro-Caribbean origin with MS satisfying McDonald's diagnostic criteria, divided into 53 cases (47.3%), the non-migrant patients (group NM), who had never left the Caribbean basin, and 59 cases (52.7%), the migrant patients (group M), who had lived in metropolitan France for at least 1 year before age 15. RESULTS: MS first manifested as an impairment of the optic nerve in 41 cases (36.6%) 25 cases (47.1%) in group NM and 16 cases (27.1%) in group M. Visual function was recovered in 13/25 cases (52%) in group NM compared to 13/16 cases (81%) in group M. Two-thirds of patients presented with a clinical ocular impairment, which was bilateral in 58.5% of cases in group NM. Fourteen cases (12.5%) met the criteria of neuromyelitis optica, nine cases (17%) in group NM and five cases (8.5%) in group M. In group NM, when the initial visual attack did not regress, the visual Expanded Disability Status Scale (EDSS) score was 5+/-1.5 ; 75% of patients had monocular blindness and 50% binocular. CONCLUSIONS: In the non-migrants (group NM), MS manifested more frequently with an optical neuropathy, the ocular impairment was more severe, and corresponded to neuromyelitis optica in 17% of the cases; a visual presentation and the absence of complete recovery from the first attack represented a factor of poor prognosis. This series is the largest description of the visual phenotype of MS in patients of African origin. The results confirm the preferential impairment of the optic nerve in the black population in the course of the disease. The migration towards an area of high prevalence of MS influences the visual phenotype in terms of a lower incidence and less severe prognosis of ocular impairment.