EFFECT OF INTRAVITREAL TISSUE-PLASMINOGEN ACTIVATOR ON EXPERIMENTAL SUBRETINAL HEMORRHAGE

Purpose: To study the effect of intravitreally injected tissue plasminogen activator (tPA) in an experimental model of subretinal hemorrhage. Methods: Autologous blood was transsclerally injected into the subretinal space in 34 albino rabbits. One day later tPA was injected into the posterior vitreous in 24 eyes and saline was injected into 10 control eyes. Lysis of the subretinal blood was assessed ophthalmoscopically and retinal function was evaluated electroretinographically. Results: In all eyes in which tPA was injected intravitreally 1 day after subretinal injection of blood, the formed subretinal clot was not visible within 24 hours of treatment. Liquefied subretinal blood that formed from clot lysis disappeared within 6 days. Conversely, in all saline-injected control animals, the subretinal clots were unchanged at 24 hours and were observed for at least 3 days after injection. As a result of the presence of subretinal blood, scotopic electroretinogram amplitudes were markedly reduced in the tPA and saline-injected groups. In many eyes, blood migrated from the subretinal space into the vitreous, but it was detected later, was less severe, and cleared more rapidly after tPA injection. Conclusion: Intravitreal injection of tPA 1 day after subretinal injection of blood in rabbits facilitated more rapid lysis of the clotted blood, however, retinal damage was not prevented.