The use of tissue plasminogen activator in experimental filtration surgery

Tissue plasminogen activator (tPA), a clot-specific fibrinolytic agent, was used as an adjunct to filtration surgery in Dutch belted rabbits to determine its effects on the outcome of filtration surgery. Thirty-eight animals that underwent a standardized posterior-lip sclerectomy in both eyes were divided into five postoperative protocol groups. In masked fashion, experimental eyes received 25 micrograms of tPA in 100 microL of diluent. Fellow eyes received 100 microL of diluent and served as controls. Group 1 received daily subconjunctival tPA. Group 2 received intracameral, followed by daily subconjunctival, tPA. Groups 3, 4, and 5 received intracameral tPA on postoperative days 1 and 2;2 and 3; and 3, 4, and 5, respectively. Intraocular pressure (IOP), quality of bleb, number of days to bleb failure, and incidence of intraocular bleeding were determined in each group. No significant tPA effect was seen in groups 1 or 2. In groups 3, 4, and 5, the tPA-treated eyes demonstrated marked reduction of IOP and improvement in the quality of the blebs lasting between 6 to 24 hours.