A multicenter trial of single-chain urokinase-type plasminogen activator thrombolytic therapy for retinal vein occlusion

A multicenter trial was conducted to evaluate the efficacy of intravenous Pro-urokinase, a singlechain urokinase-type plasminogen proactivator, in improving visual acuity lost due to retinal vein occlusion. Two doses of Pro-urokinase were evaluated, 3,000 IU injected daily for 3 days or 6,000 IU injected daily for 3 days. Visual acuity measured immediately after the last injection was found to be improved in 3 (30.0%) of 10 patients who received the lower dose and in 10 (66.7%) of 15 patients who received the higher dose. Evaluation of hematological values during therapy indicated activation of the fibrinolysis system during administration of Pro-urokinase. However, no improvement in either retinal circulation or retinal function could be detected from evaluation of electroretinography results or visual field measurements, so the mechanism by which visual acuity was improved could not be identified. Further evaluation may therefore be needed of the methods for measuring retinal circulation and function. One month after the end of treatment, the post-treatment improvement in visual acuity was maintained in only 2 (22.2%) of 9 patients who received the lower dose and 4 (28.6%) of 14 patients who received the higher dose of Pro-urokinase. It was concluded that long-term maintenance of improved visual acuity is the appropriate measure of the efficacy of this treatment.