The Global Prevalence of Optic Neuritis: the ON-COLOUR Study

Introduction: Optic neuritis (ON) is an acute condition characterized by inflammation or degeneration of the optic nerve, often arising from infections or immune-related inflammatory diseases. Objectives/Aims: Prevalence offers essential insights into the disease's spread and serves as a key indicator in epidemiology and public health. With this study we aimed to perform an indepth literature review to assess the prevalence of ON worldwide. Methods: Following PRISMA guidelines, a literature synthesis was conducted, focusing on articles published between January 2010 and March 2025 in English on PubMed. To identify relevant studies, the following keywords sequence was used: ((optic neuritis[Title]) AND (prevalence[Title/Abstract])). Results: A review of articles from the past 15 years on the prevalence of ON was conducted, yielding 41 results. Of these, 5 full-text articles were assessed, and 3 studies were selected for inclusion. Two of the articles focused on the prevalence of ON in the European adult population, while one study from Asia included both pediatric and adult groups. The prevalence of ON ranged from 7.87 to 114.8 per 100,000 individuals in Europe, while for Asia, estimates were 7.68 among children and 19.01 among adults. Conclusion: Prevalence estimates of ON at global level are consistent and indicate an increase compared to earlier surveys. Higher prevalence estimates were identified in regions at higher latitudes, as it is seen for multiple sclerosis, the condition most frequently associated with ON. Furthermore, all reported estimates were higher in women than in men across all age groups. However, current knowledge on the prevalence of ON is limited, and the presence of a limited number of recent epidemiological studies makes it difficult to accurately assess the global picture. For a clearer detection and understanding of epidemiological trends following the introduction of new diagnostic criteria for ON and the impact of the COVID-19 pandemic, longitudinal population-based assessments in all geographic regions is claimed.