Natural history of the visual impairment of relapsing neuromyelitis optica.

To describe the clinical features and natural history of the visual impairment of relapsing neuromyelitis optica.Prospective observational case series.Thirty patients of Afro-Caribbean origin with neuromyelitis optica and 47 patients with multiple sclerosis.A complete ophthalmologic examination was performed with each ocular attack and during a remission period at least 6 months after the last attack.Incidence of unilateral and bilateral optic neuritis and incidence of unilateral and bilateral severe visual loss, defined as visual acuity (VA) < or = 20/200.Twenty-eight patients (93%) with neuromyelitis optica were female and 2 (7%) were male. The mean age of onset was 30+/-10.5 years. Mean disease duration was 9.5+/-5.4 years. Neuromyelitis optica first manifested by an episode of optic neuritis in 23 cases (76.6%), bilateral in 4. The average number of ocular attacks per patient was 2.7+/-1.6. Twenty-one patients (70%) showed impairment in both eyes. Median times from onset to unilateral optic neuritis, bilateral optic neuritis, mono-ocular severe visual loss, and binocular severe visual loss were 0+/-0.08, 1+/-1.6, 2+/-0.8, and 13+/-3 years, respectively. Fifteen patients (50%) experienced severe visual loss in both eyes and 6 (20%) in one eye. Severe visual loss occurred in as few as 2 attacks.This study is the largest series of relapsing neuromyelitis optica in a population of African descent. Neuromyelitis optica's visual impairment is very severe; it contrasts drastically with that typically observed in multiple sclerosis. We confirmed that the prognosis for optic neuritis in patients with neuromyelitis optica is worse than the prognosis in patients with multiple sclerosis.