[Eosinophilic granulomatosis with polyangiitis presenting with ischemic optic neuropathy].

A 60-year-old man with a history of bronchial asthma and nasal polyp presented with loss of vision in the right eye. His visual loss progressed within a single day, and he presented to our hospital 5 days after the onset of the symptom. Fundoscopy showed swelling and hemorrhage of the right optic disc. Blood tests revealed increased eosinophils, C-reactive protein, and perinuclear anti-neutrophil cytoplasmic antibody. Cerebrospinal fluid was normal. Cranial MRI showed local enhancement of the right optic disc and posterior ciliary arteries. He was diagnosed with arteritic anterior ischemic optic neuropathy caused by eosinophilic granulomatosis with polyangiitis (EGPA). High dose intravenous methylprednisolone was started on presentation, but the patient showed no improvement in visual function. Although a rare complication, ischemic optic neuropathy associated with EGPA should be noted, as this is an emergent condition and requires prompt diagnosis and treatment.