Probable Posterior Ischemic Optic Neuropathy Associated with Acute Fungal Sinusitis

Purpose: We report a case of probable posterior ischemic optic neuropathy in a patient with acute fungal sinusitis.Case Summary: An 81-year-old male patient presented with sudden-onset visual loss in his left eye 3 weeks prior to presentation. His best corrected visual acuity was 0.6 in his right eye and light perception in his left eye. Pupillary size was 3 mm in both eyes, and a relative afferent pupillary defect was detected in his left eye. In fundus examination, diabetic retinopathy was found, and cup/disc ratios were increased in both eyes, but disc swelling and hemorrhage were not observed. Fluorescein angiography did not indicate filling delay, defects, or leakage of discs in either eye. Magnetic resonance imaging of the brain revealed multi-sinusitis in the sphenoid, ethmoid, and frontal sinuses. No bony defects or erosion were found around the optic canal or orbital apex during endoscopic surgery; however, histological examination revealed aspergillosis. The patient was diagnosed with posterior ischemic optic neuropathy caused by acute fungal sinusitis.Conclusions: When elderly patients with uncontrolled diabetes experience sudden visual disturbances without ocular pain, posterior ischemic optic neuropathy with fungal sinusitis should be considered as a differential diagnosis. Immediate imaging studies and appropriate treatment should be performed.