In cases of myelin-oligodendrocyte glycoprotein antibody-positive optic neuritis (MOGON) with severe visual field impairment at onset, the visual field deficits may remain following steroid pulse therapy. In such cases, additional treatment should be considered. To clarify the steroid responsiveness of MOGON, further accumulation of cases is desired. The gene discussed is OMG; the disease is optic neuritis.