Evaluation of topically administered tissue plasminogen activator for intraocular fibrinolysis in dogs

Fibrin clots were induced in eyes of dogs by injection of autogenous citrated plasma into the anterior chamber. Twenty-four hours after clot formation, one 50-microliters drop of tissue plasminogen activator at a concentration of 5 mg/ml (group 1, n = 7) was administered topically 9 times at 5-minute intervals, or a collagen shield that was hydrated with tissue plasminogen activator at a concentration of 5 mg/ml (group 2, n = 7) was applied. The contralateral eye served as a nontreated control. Serial photographs were taken of the fibrin clots after topical application of tissue plasminogen activator. Computerized morphometric analysis was then used to evaluate changes in cross-sectional surface area of the fibrin clot. There was no significant mean percentage decrease in clot surface area of treated eyes of group-1 dogs or in treated eyes of group-2 dogs. In addition, there was no significant difference in mean percentage decrease in clot surface area between treated eyes of group-1 and group-2 dogs.