Conversion Rate of Pediatric Optic Neuritis to Demyelinating Disorders: the ON-COLOUR Study

Introduction: Optic neuritis (ON) is an acute inflammation of the optic nerve, which frequently leads to damage of the myelin sheath and presents as an early clinical sign of demyelinating disorders, particularly multiple sclerosis (MS). Objectives/Aims: This study aimed to evaluate the global conversion rate of ON to demyelinating disorders in the pediatric population through a literature review. Methods: A literature review was conducted in line with PRISMA guidelines, focusing on PubMed articles published in English between 01/2015 and 03/2025, focused on the pediatric population. The search combined “optic neuritis” in the title with terms such as “conversion,” “prognostic,” “risk,” or “epidemiology,” and “multiple sclerosis,” “NMO,” “MOG,” or “demyelinating” in the title or abstract. Results: Out of 41 articles reviewed, 10 were included in the final analysis. Most studies were retrospective, with follow-up periods of 1 to 10 years, and originated from diverse global regions. Conversion rates from ON to demyelinating diseases (MS, NMO, MOG-ON) varied widely. MS conversion was lowest in Asian and US studies (1–14%) and highest in European cohorts (up to 42%). NMO conversion rates ranged from 1.95–5.88% in Europe and up to 11% in Asia and the USA. Recurrence rates were higher in Asia (12–25%) compared to Europe and the USA (up to 7% and 13%, respectively). Visual outcomes were generally favorable, with recovery rates of up to 89% within one year. Conclusion: An increased risk of MS conversion is linked to age >10 years, female sex, demyelinating brain lesions on Magnetic Resonance Imaging, positive cerebrospinal fluid oligoclonal bands, and unilateral ON. While visual recovery is generally good in isolated ON, outcomes are poorer in cases progressing to MS or NMO. Based on these findings, early diagnostic evaluation is recommended in pediatric ON, including neurological examination, brain MRI, and antibody testing (with serological screening for MOG-IgG and AQP4-IgG antibodies).