The Role Of Plasmin In Facilitating Posterior Vitreous Detachment In Eyes Undergoing Macular Hole Surgery

Abstract

Plasmin is best known for its role m the fibrinolytic cascade, where it is converted from plasminogen by either tissue plasminogen activator (t-pa) or urokinase (upa). Plasmin degrades a variety of substances in the extracelluar matrix, including laminin and fibronectin, which have been implicated in normal vitreoretinal adhesion. In addition to its action on fibrin, plasmin activates latent matrix metalloproteinases (collagenases), with break down of the vitreous gel. We investigated toxicity and efficacy of plasmin enzyme on rabbits eyes, at varying doses, starting from a 0.1 IU reaching up to a 3.0 IU. At the latter mentioned dose, no evidence of toxicity was demonstrated through the analysis of electrophysiologic data and histopathologic examination techniques, as compared to control eyes that received an intravitreal injection of a 0.1 ml of BSS instead. With regards to efficacy, intravitreal injection of plasmin enzyme in rabbits eyes, was shown to induce liquefaction of the vitreous gel, and a separation of the posterior hyaloid face.