Objective:

Evaluate whether bilateral optic neuritis (BON) at MOGAD onset represents a distinct phenotype requiring more aggressive treatment and assess the impact of early maintenance therapy on relapse risk.

Background:

BON is a common presentation in MOGAD, but optimal treatment strategies remain unclear. We hypothesised that BON represents a higher-risk phenotype warranting aggressive acute treatment and early maintenance therapy initiation.

Design/Methods:

Retrospective single-centre cohort study of 141 MOGAD patients (51 BON, 90 unilateral ON [UON]) with median follow-up of 18.1 months. We compared treatment patterns, including acute therapies (IVMP, IVIG, PLEX) and early maintenance initiation (<90 days), between groups. Cox proportional hazards models assessed relapse risk adjusting for age, sex, acute treatment intensity, and maintenance therapy timing.

Results:

BON patients received significantly more aggressive treatment than UON: IVMP (90.2% vs 74.4%, p=0.024), PLEX (23.5% vs 10.0%, p=0.030), aggressive acute therapy with IVIG/PLEX (27.5% vs 12.2%, p=0.041), and early maintenance therapy (51.0% vs 25.6%, p=0.003). With more intensive treatment, BON patients had numerically lower crude relapse rates (37.3% vs 48.9%). In adjusted Cox models, BON showed no significant difference in relapse risk compared to UON (HR=0.92, 95%CI: 0.49-1.74, p=0.807). Early maintenance therapy showed a trend toward reduced relapse risk (HR=0.68, 95%CI: 0.33-1.38, p=0.286), as did aggressive acute treatment (HR=0.44, 95%CI: 0.16-1.22, p=0.114), though neither reached statistical significance. No significant interaction was found between BON status and early maintenance therapy (interaction HR=0.72, p=0.610).

Conclusions:

BON patients receive substantially more aggressive acute and preventive treatment in clinical practice, likely reflecting perceived higher risk. After adjustment for treatment differences, BON and UON patients have similar relapse risks, suggesting that current intensive treatment approaches may be appropriately mitigating risk in BON. Early maintenance therapy and aggressive acute treatment show trends toward benefit that warrant investigation in larger prospective studies. These findings support risk-stratified treatment approaches based on initial presentation phenotype.