The Characteristics of Retinal Emboli and its Association With Vascular Reperfusion in Retinal Artery Occlusion

Purpose: To analyze the characteristics of retinal emboli and their association with vascular reperfusion in retinal artery occlusion (RAO). Methods: In this retrospective comparative case series, we analyzed emboli in patients with acute central retinal artery occlusion (CRAO) or branch retinal artery occlusion (BRAO) and visible emboli, and analyzed vascular reperfusion in patients with visible emboli causing blockage of perfusion. The patients were divided into emboli "movement" and "no movement" groups and their vascular reperfusion states were compared. Results: There were 52/248 (21%) eyes with RAO and visible retinal emboli (31/187 [17%] eyes with CRAO and 21/61 [34%] eyes with BRAO) showing various embolic features. Platelet-fibrin emboli were observed most commonly, and showed the earliest and highest rate of movement. In the movement group, which comprised platelet-fibrin (60%) and cholesterol (40%) emboli, early complete reperfusion was observed in 80% of eyes; however, 67% of eyes in the no movement group, comprising cholesterol (67%) and calcific (33%) emboli, showed late incomplete reperfusion. There were no cases of permanent vascular blockage. The mechanisms of vascular reperfusion could be summarized as complete degradation, peripheral migration, partial dislodgement, angiophagy, and collateral circulation. Conclusions: Retinal emboli in RAO patients have various characteristics that affect their movement. Movement of emboli may affect vascular reperfusion. Various mechanisms are associated with vascular reperfusion, including in cases without movement of emboli. These mechanisms may apply to cerebrovascular occlusion and stroke in general.