Abstract
Purpose: :
Retinal endovascular fibrinolysis, aiming at early restoration of blood flow after retinal vein occlusion, has been applied in pilot studies with variable success. We hereby describe the technique of retinal endovascular fibrinolysis to directly reopen an occluded retinal vein, as well as the use of a simple micropipette for puncture, the characteristics of successful microinjection, and the tissue damage on the microinjected site.
Methods: :
Minipigs were given a bolus of 10% fluorescein (1 ml) into the femoral vein. Fifty units of thrombin were applied locally onto a retinal vein and this site was exposed to weak Argon laser. A curved micropipette with a sharp edge (50 µm) served for puncture of the occluded vein and for immediate endovascular injection of t–PA (50 µg/ml). The lesion site was analyzed histologically.
Results: :
The described model of retinal vein occlusion led to thrombotic venous obstruction without inducing overt damage to the vascular wall. Successful microinjection was indicated by restoration of continuous endovascular flow, by unaffected circulation in collateral veins and arteries, and by absence of optic disc ischemia and of venous wall bleeding. Micropuncture induced thrombus formation at the microinjection site that was prevented by immediate injection of t–PA. The design of the micropipette was appropriate for successful micropuncture, microinjection, and reopening of the occluded vein.
Conclusions: :
Retinal endovascular fibrinolysis constitutes a promising method of retinal venous micropuncture and reperfusion in the treatment of retinal vein occlusion. Thrombus formation at the injection site can be prevented by immediate injection of t–PA. Whether increased endovascular pressure during reperfusion or the use of t–PA can reopen the occluded vein remains to be defined. To evaluate whether reperfusion of an occluded vein has a beneficial effect on retinal function, a prospective clinical trial on retinal endovascular fibrinolysis was initiated.
Keywords: vascular occlusion/vascular occlusive disease • vitreoretinal surgery • injection