Video microscope recording of the dynamic course of thrombosis and thrombolysis of the retinal vein in rabbits.

Purpose: The purpose of this study was to investigate the dynamic course of experimental thrombosis and thrombolysis of the retinal veins. Methods: Dynamic changes in the blood flow in the retinal veins were documented on a digital recorder through a microscope-mounted video camera and were analyzed on a monitor by video playback. Photochemical thrombus formation was induced by intravenous injection of 30% Rose Bengal followed by endoillumination of individual branch retinal veins of the eyes of 20 anesthetized pigmented rabbits. Subsequently, 10 rabbits were treated with an infusion in an ear vein of 3 mg/kg recombinant tissue plasminogen activator, whereas 10 control rabbits were administered with similar volumes of normal saline solution. Occlusion and recanalization were confirmed histologically and assessed by video microscopy. Results: At the site exposed to light, photochemical injury resulted in the formation of a white thrombus, stagnation of blood flow, and subsequent complete venous occlusion in 20 rabbits. In this study, of the 10 animals in the recombinant tissue plasminogen activator treatment group, 9 ( 90%) showed evident thrombolysis, whereas none of the control group animals showed evident thrombolysis. The video showed that the massive thrombus disrupted into nonuniform fragments, which were quickly washed away by the blood flow, and the circulation was reestablished with no recurrence of secondary obstruction. Conclusion: In vivo data suggest that video microscopy may provide a visual approach for observing the dynamic changes occurring during experimental thrombus formation and lysis by the early administration of recombinant tissue plasminogen activator; this approach may assist in future investigation of thrombus research of ocular fundus. RETINA 30: 966-970, 2010