A Painless Loss of Vision

A 49-year-old patient presents with central retinal artery occlusion. Subsequent imaging reveals thrombus in the carotid artery. Free-floating thrombus (FFT) in the common or internal carotid artery is an uncommon but important diagnosis in the patient who presents with cerebral or retinal ischaemia or infarction. FFT may be idiopathic, secondary to either an underlying arterial abnormality (carotid dissection or atherosclerotic plaque), or a procedural complication following carotid endarterectomy or stenting. The diagnosis is made through non-invasive imaging (carotid Doppler ultrasound, CT angiography or MR angiography) or at catheter angiogram. A characteristic “doughnut sign” of intraluminal filling defect surrounded by contrast is described on axial imaging. Optimal management is debated, and may differ according to aetiology. Treatment options include antithrombotic and anticoagulant drugs, carotid endarterectomy or carotid artery stenting.