Abstract
PURPOSE: To report a case of primary antiphospholipid syndrome presenting with isolated homonymous superior quadrantanopsia. OBSERVATIONS: A 50-year-old Korean man presented with subjective visual disturbance for 1 month. Visual field testing showed a right homonymous superior quadrantanopsia. Brain magnetic resonance imaging (MRI) revealed an old infarct in his left occipital lobe and multiple lesions in other areas of the brain. Laboratory tests showed a marked increase in serum anti-β2 glycoprotein I antibody, which remained elevated after 12 weeks. He was diagnosed with primary antiphospholipid syndrome and started anticoagulation therapy. CONCLUSIONS AND IMPORTANCE: This is the first case report of primary antiphospholipid syndrome presenting with isolated homonymous quadrantanopsia. Antiphospholipid syndrome should be considered as a differential diagnosis in patients with homonymous visual field defects accompanying multiple cerebral infarcts.