Amaurosis fugax progressing to retinal artery occlusion with anterior migration of a retrobulbar embolus on orbital color Doppler imaging

Purpose

Orbital color Doppler imaging (CDI) is useful in the evaluation of sudden monocular vision loss, providing information on etiology which may guide management. We present two cases of amaurosis fugax progressing to retinal artery occlusion (RAO) associated with migration of a hyperechoic particle within the central retinal artery (CRA) and altered vascular dynamics found on CDI.

Observations

Both patients presented with amaurosis fugax, and CDI revealed a hyperechoic particle 2.8 mm from the optic nerve head in both patients. Patient 1 was found to have severe aortic stenosis and a thoracic aortic aneurysm and was managed with dual antiplatelet therapy (DAPT) while awaiting evaluation for cardiothoracic surgical repair. Ten days later, Patient 1 returned with a central RAO, and a repeat CDI showed a 1.0 mm anterior migration of the embolus with reduced CRA blood velocity and an increased resistivity index. Patient 2 was managed with DAPT and oral corticosteroids, but symptoms recurred during steroid tapering which necessitated a prolonged course of steroids. Systemic complications required reduction of steroid dosing, and the patient developed a branch RAO six months after initial presentation. Repeat CDI revealed a 0.9 mm anterior migration of the embolus, with increased CRA blood velocity and resistivity index. Systemic thrombolysis with tissue plasminogen activator and resumption of steroids did not result in visual improvement in Patient 2.

Conclusions and importance

The presence of a hyperechoic particle in the CRA on CDI can be seen with amaurosis fugax, and anterior migration with subsequent alterations in CDI parameters may correlate with clinical progression to embolic retinal ischemia. Visualization of an embolus may predict nonresponse to thrombolytic or anticoagulation-based treatment.