Incidence of Optic Neuritis Among Omani Patients with Multiple Sclerosis at the Sultan Qaboos University Hospital, Muscat, Oman

Objectives: Multiple sclerosis (MS) is a chronic, multifaceted, heterogeneous autoimmune disease, with optic neuritis (ON) being a common early manifestation. This study aimed to estimate the incidence of ON among Omani patients with MS. Methods: This retrospective cross-sectional study included all Omani patients diagnosed with MS at the Sultan Qaboos University Hospital, Muscat, Oman, between January 1991 and December 2019. Data were collected from the neurology registry and electronic medical records. The data was analysed descriptively using univariant and multivariant statistical techniques. Results: Of the 185 patients diagnosed with MS during the study period, 170 were included in the analysis. The male-to-female ratio was 1:3 and the mean age was 28 years. The incidence of ON in the population was 28.8%, with 83.7% of ON patients presenting with relapse-remitting MS (RRMS). Overall, 28.6% presented with ON as an initial manifestation of MS, while 42.8% developed ON at a later stage. Most patients (49.4%) were from higher-latitude regions of Oman, like Muscat and Al Batinah. Conclusion: The incidence of both MS and ON increased over the study period. While the overall incidence was low in comparison with Western data, it was similar to rates reported elsewhere in the Arabian Peninsula. Overall, ON was the most common manifestation of MS in the cohort, with younger female patients more frequently presenting with both MS and ON. There was a significant association between the RRMS subtype and ON presentation. Keywords: Demyelinating Diseases; Optic Neuritis; Multiple Sclerosis; Multiple Sclerosis, Relapsing-Remitting; Incidence; Epidemiology; Oman