Incidence of optic neuritis among Afro-descendant, a cohort study.

Background: Optic neuritis (ON) is a multifactorial condition with a strong association with ethnicity.

Objectives: We conducted a retrospective cohort study in a Caribbean Island, Martinique, French West Indies to assess the incidence and characteristics of ON among an Afro-descendant (AD) population.

Methods: We reviewed medical records of all patients presenting ON at the Fort de France University Hospital, Martinique between 2018 and 2022. We analysed clinical, paraclinical, and biological examinations at onset and during follow-up (6 months, 1, 2 and 3 years). ON was confirmed after a neuro-ophthalmological evaluation according to the latest criteria defined in the Lancet, 2022.

Results: Overall, 44 patients with a condition suggestive of ON were evaluated, out of which 29 fulfilled the criteria for ON. The overall incidence was 1.61 (95% CI: 1.12-2.08) per 100,000 person-years. The final diagnosis was distributed as follows: neuromyelitis optica spectrum disorder (NMOSD) (10%), myelin oligodendrocyte glycoprotein (MOG) ON (20%), multiple sclerosis (35%), single isolated ON (24%), relapsing isolated ON (7%) and (4%) unclassified diagnosis.

Conclusion: This is the first cohort study assessing the incidence of ON and its characteristics among AD. We found a high proportion of severe disease, such as NMOSD and MOG-associated disease.