A 57-year-old woman presents with 1 month of transient, painless vision loss OD, typically beginning with flashing lights and progressing to light perception vision. The diagnosis is asospastic amaurosis fugax causing transient monocular vision loss. As vasospastic amaurosis is rare, diagnosis should be made only after excluding visual and life-threatening vascular conditions in susceptible individuals such as carotid stenosis, cardiac emboli (valvular disease and paradoxical emboli), hypercoagulable states (antiphospholipid antibody syndrome), and vasculitis. In some instances, fundus can provide important clues such as cholesterol, calcific, or platelet-fibrin emboli, or choroidal changes (Elschnig spots). MR angiography should be added if there is any concern for carotid dissection. Because vasospastic amaurosis has been associated with polyarteritis nodosa and eosinophilic vasculitis, additional autoimmune serologies (ANA and ANCA) should be considered.