This study aims to provide a comparative analysis of MOG-associated disorders (MOGAD) and Neuromyelitis Optica Spectrum Disorders (NMOSD), highlighting their distinct characteristics, diagnostic challenges, and implications for disease management.

Optic neuritis (ON) is a common initial clinical presentation for both MOGAD and NMOSD, formerly categorized as seronegative variants of Multiple Sclerosis. Advances in diagnostic assays have identified specific antibodies, such as anti-MOG-IgG1 and anti-AQP4-IgG, enabling the reclassification of these disorders as separate entities.

Case report

 This report presents case studies of two female patients, aged 54 and 50, both exhibiting acute painful loss of vision (LOV). Clinical examinations, including visual acuity assessment, relative afferent pupillary defect (RAPD) evaluation and diagnostics like visual evoked potential (VEP) testing, and magnetic resonance imaging (MRI), showing optic nerve enhancements, supported the diagnoses of optic neuritis in both. Serological testing confirmed the presence of anti-MOG-IgG1 antibodies in one case and anti-AQP4-IgG antibodies in the other, distinguishing MOGAD from NMOSD.

The patient with MOGAD, experiencing her first ON episode, showed significant improvement following steroid treatment. However, the NMOSD patient, with a history of recurrent ON episodes, did not respond adequately to steroids and required Rituximab therapy. Both patients remained relapse-free during follow-up.

This comparative analysis underscores the importance of distinguishing between MOGAD and NMOSD, elucidating their different prognostic trajectories and therapeutic outcomes. Unlike MS or MOGAD, NMOSD typically causes profound necrosis and cavitation affecting both gray and white matter rather than demyelination. Consequently, individuals with MOGAD commonly manifest favorable responses to treatment, however NMOSD patients often have recurrent episodes necessitating intensified immunomodulatory regimens. Hence, timely serological testing guided by a high clinical suspicion facilitates accurate diagnosis and initiation of appropriate treatment, thereby improving disease outcomes.