Acute Unilateral Anterior Ischemic Optic Neuropathy Secondary to Optic Nerve Head Drusen: Report of a Rare Coexistence.

A 45-year-old white male noticed on awakening the painless loss of inferior vision in the left eye 2 days ago. He was otherwise well and his medical history was unremarkable. Visual acuity was 20/20 in OD and 20/32 in OS with a left inferior altitudinal defect and right blind spot enlargement demonstrable on visual field test. On fundus examination, both disc margins were blurred and the left disc was diffusely oedematous, with linear haemorrhages in the adjacent nerve fibre layer. Radiologic imaging and laboratory tests were unremarkable. Bilateral optic nerve head drusen (ONHD) was demonstrated by optical coherence tomography and fundus autofluorescence imaging. Unilateral acute non-arteritic anterior ischemic optic neuropathy (NAION) and concomitant bilateral ONHD were diagnosed. NAION may develop secondary to ONHD. Therefore, clinicians should be aware of this rare association and inform the patients about this risk. Patients with ONHD should be followed-up periodically in terms of possible ischemic complications.