The natural history of optic neuritis in Asian patients
With the publication of criteria for the diagnosis of neuromyelitis optica (NMO), and the discovery of the anti-NMO antibody, it is now known that many Asian patients have a different disease. The natural history, prognostic factors for visual recovery, and risk of developing subsequent neurological symptoms, as described by previous studies, may not apply to Asian populations. For example, acute bilateral optic neuritis, which is uncommon in adult Caucasian patients, may be more frequent in Asians. Previous studies in Asian patients with optic neuritis were either retrospective or cross-sectional. Hence, there is a need for a prospective study with long-term follow up to describe the natural history of optic neuritis in Asian patients.
Optic neuritis, which may be a precursor to multiple sclerosis (MS), is an uncommon disease in Asian patients. The Asian Collaborative Longitudinal Optic Neuritis Epidemiology (ACLONE) is an observational cohort study that assessed the risk of recurrent optic neuritis and/or progression of further neurologic events, either MS or neuromyelitis optica (NMO) in Asian patients with first ever optic neuritis for long-term follow up. . A total of 112 patients were recruited from Singapore, Taiwan, South Korea and Malaysia.
Secondary aims were to study the presenting characteristics and visual outcome, and to identify risk factors for development of either MS or NMO. Optic neuritis in Asian patients has significantly different presenting characteristics from the classic description. However, in the majority of the patients it is usually a benign disease, with good visual outcome and no further events.
At the time of this study, the NMO antibody assay was not widely available and so this was not obtained. This was an observational study, therefore acute treatment including the use of pulse steroids was left to the discretion of the treating clinician, as it is generally agreed that steroid use is not disease-modifying (i.e. it does not prevent the underlying disease from manifesting as MS or NMO).
Results confirm that the clinical characteristics of optic neuritis in Asian patients differ from classic optic neuritis.