Prevention of clot formation in cat retinal vein by systemic and subconjunctival urokinase

The thrombolytic effect of urokinase was tested on cat retinal vein thrombus induced by argon laser photocoagulation. At various time intervals after thrombosis, intravenous infusion or subconjunctival injections were given. Subconjunctival normal saline injections were used for controls. In vitro subconjunctival urokinase prevented thrombus organization if given within six hours of thrombosis. Subconjunctival injections of urokinase vs normal saline were also studied in vivo in a masked fashion. At intervals of three to 24 hours following thrombosis, 11 cats were treated with subconjunctival urokinase in one eye and normal saline in the 11 fellow eyes. Within ten days after thrombosis, the vein was patent in eight (72%) of the 11 eyes treated with urokinase and in one (9%) of the 11 control eyes.