Anterior ischaemic optic neuropathy as an initial manifestation of eosinophilic granulomatosis with polyangiitis: The importance of early and appropriate immunosuppressive treatment for visual recovery.

Eosinophilic granulomatosis with polyangiitis (EGPA) is an antineutrophil cytoplasmic antibody-associated vasculitis, affecting various organs. Although ocular involvement occurred in 6.8-11.1% of patients, anterior ischaemic optic neuropathy (AION) is rare. We present the case of a 57-year-old woman with an 11-year history of asthma who developed sudden, painless visual loss in her left eye. On admission (3 days after symptom onset), visual acuity was counting fingers in the left eye and 20/20 in the right eye. Funduscopy showed left optic disc oedema. Magnetic resonance imaging revealed intravitreal protrusion of the left optic nerve head with restricted diffusion and local contrast enhancement of the left intraorbital and retrobulbar fat. Given also peripheral eosinophilia, myeloperoxidase-antineutrophil cytoplasmic antibody positivity, mononeuritis multiplex, nasal polyps, sinusitis, and pulmonary involvement, EGPA with AION was diagnosed. Intravenous methylprednisolone pulse was urgently administered, followed by mepolizumab 2 weeks later. Although eosinophilic inflammation and imaging findings improved, visual acuity remained unchanged over 1 year. A literature review identified 14 cases of EGPA-associated AION. Including our case, 11 cases with available data (14 eyes) were analysed. Overall, visual recovery was observed in 29%. Among 12 eyes with severe visual impairment before treatment, visual recovery occurred only in those treated earlier or with cyclophosphamide except for one, whereas no recovery occurred in those with delayed treatment or without cyclophosphamide. This case highlights the potential of AION as an initial manifestation of EGPA. Both earlier initiation and adequate intensity of immunosuppressive therapy, particularly including cyclophosphamide when clinically appropriate, may be important for visual recovery in EGPA-associated severe AION.