THE USE OF INTRAVITREAL TISSUE-PLASMINOGEN ACTIVATOR IN THE TREATMENTOF EXPERIMENTAL SUBRETINAL HEMORRHAGE IN THE PIG MODEL

Purpose: To clinically and surgically evaluate clot lysis in an animal model of subretinal hemorrhage ar-ter intravitreal injection of tissu e plasminogen activator. Methods: Autologous subretinal hemorrhages we re created via a transvitreal approach in 18 pigs, The next day (day 1 ) animals were randomly selected to receive either an intravitreal inj ection of 0.1 mL balanced salt solution or 0.1 mt tissue plasminogen a ctivator (25 mu g) followed by observation or vitrectomy a day later. On day 2, six pigs (all treated with tissue plasminogen activator) und erwent a vitrectomy in which aspiration of the subretinal hemorrhage w as attempted. The other eyes were evaluated for clot lysis by ophthalm oscopy at days 3, 10, and 30. All eyes were examined histopathological ly. Results: The eyes that had been treated with tissue plasminogen ac tivator demonstrated a color change at the peripheral margin, which su ggested that clot lysis had occurred. At the time of the vitrectomy, t he clots were liquefield partially; removal by aspiration alone, howev er, was not possible, Photoreceptor damage was moderate to severe by d ay 10 in all eyes, whether they were treated with tissue plasminogen a ctivator or balanced salt solution. All eyes that underwent vitrectomy had moderate to severe photoreceptor damage. Conclusions: In this ani mal model, intravitreal tissue plasminogen activator was associated wi th features that suggested partial clot lysis; tissue plasminogen acti vator did not produce sufficient lysis to allow surgical removal by as piration alone, however.