Eosinophilic Granulomatosis with Polyangiitis Presenting as Unilateral Acute Anterior Ischaemic Optic Neuropathy.

Eosinophilic granulomatosis with polyangiitis (eGPA) is a rare vasculitis of small-medium sized vessels that can cause both anterior and posterior ischaemic optic neuropathies. Herein, the authors present a rare case of eGPA presenting initially as an acute unilateral anterior ischaemic optic neuropathy from short posterior ciliary artery vasculitis. The diagnosis presented a challenge as clinical and histopathological evidence suggested allergic rhinosinusitis, and no invasive fungal sinusitis was found. The high serum eosinophilia, asthma, optic neuropathy and paranasal sinus abnormalities fulfilled the criteria for a diagnosis of eGPA. Furthermore serum was positive for myeloperoxidase antibodies. Subsequently the case was successfully treated with oral glucocorticoids and intravenous rituximab.