Fibrinolysis of experimental subretinal haemorrhage without removal using tissue plasminogen activator.

Abstract

Human recombinant tissue plasminogen activator (rt-PA) fibrinolysis of subretinal haemorrhage with concomitant removal has been shown to reverse the natural history of photoreceptor degeneration in experimental subretinal haemorrhages if evacuated within 7 days. The aim of the study was to determine whether fibrinolysis of subretinal haemorrhage without concomitant removal would offer a simpler approach with similar photoreceptor sparing. A neodymium YAG laser was used to create experimental subretinal haemorrhages beneath the holangiotic retina of the cat. Tissue plasminogen activator (10 micrograms/ml) was injected into 4 day old subretinal haemorrhages to evaluate its effect on altering the natural history of retinal degeneration. Light and electron microscopy were used to study the histopathological effect. The injection of rt-PA into large 4 day old subretinal haemorrhages without concomitant removal did not alter the natural history of retinal degeneration. In fact, a second focus of retinal degeneration occurred at a gravity dependent inferior site where the subretinal haemorrhages had migrated. There was no therapeutic benefit from the injection of rt-PA into subretinal haemorrhages without con-comitant removal in this cat model.