Abstract
Optic perineuritis (OPN) is an intraorbital inflammatory disease that targets the optic nerve sheath, which can cause severe vision loss. OPN has been recently reported to be sometimes caused by myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD). MOGAD is rarely reported to be complicated with other autoimmune diseases. We report the first rare case of MOG-associated OPN complicated with granulomatous with polyangiitis (GPA). The vision loss, in this case, was initially considered to be caused by cavernous sinusitis in GPA. However, she was diagnosed with MOGAD with serial MRI findings and positive MOG antibody and had been successfully treated with glucocorticoid and tocilizumab for one and half years. This case emphasized the importance of evaluating the MOG antibody in a patient with recurrent OPN, complicated with vasculitis.