[Systemic lysis therapy in retinal vascular occlusions].

In the management of acute major vessel occlusion, the use of fibrinolytic agents such as recombinant tissue plasminogen activator (rt-PA), urokinase or streptokinase is widely accepted. Today, the spectrum of indications for thrombolytic drugs comprises acute myocardial infarction, lung embolism, ischaemic stroke, deep vein thrombosis and acute arterial occlusions of the lower limbs. In view of the histopathological and clinical features of retinal vessel occlusion, fibrinolysis aimed at early restoration of blood flow appears to be a promising therapeutic approach. Basically, it is of some concern that the systemic administration of fibrinolytic agents is associated with a haemorrhagic risk. Since this includes cerebral haemorrhage or gastrointestinal bleeding, the choice of an appropriate intravenous thrombolytic therapy in a non-life threatening situation such as central retinal artery occlusion (CRAO) or central retinal vein occlusion (CRVO) should be based on minimising the risk of adverse events. Furthermore, the fibrinolytic treatment of choice should be able to produce rapid and complete restoration of retinal capillary and arterial or venous blood flow and maintain patency long enough for retinal salvage to take place. In this article, we review several studies of fibrinolytic therapy in patients with retinal vessel occlusion to determine whether this treatment is likely to improve major clinical outcomes. Moreover, we review the large scale trials of fibrinolysis in myocardial infarction and acute ischaemic stroke to evaluate safety and efficacy of various thrombolytic regimens. Furthermore, we report on our results of fibrinolytic therapy with low dose rt-PA in patients with retinal artery occlusion and ischaemic central retinal vein occlusion. In light of the fact that the occurrence of bleeding complications constitutes a dose dependent problem, we conclude that the use of low dose regimens should be the ideal approach to fibrinolysis in retinal vessel occlusion. Although the results of our pilot studies must be interpreted with caution, we believe that the administration of low-dose rt-PA (50 mg) in a frontloaded manner (= simultaneous administration of rt-PA and intravenous heparin) constitutes a reasonable treatment option in patients with central retinal artery occlusion (CRAO) or ischaemic retinal vein occlusion (RVO), recent onset of symptoms (CRAO < or = 12 h, RVO < or = 11 d) and severe visual loss (< or = 20/50). Because of these limitations and the numerous contraindications of fibrinolytic therapy, only a limited number of patients will be suitable for this treatment. In view of the poor visual and ocular prognosis in severe retinal vessel occlusion, controlled clinical trials are needed to determine the benefit of thrombolysis in the management of this disease.