Randomised controlled trials (RCTs) that evaluated antithrombotic drugs (vitamin K antagonists, heparin, antiplatelet drugs) and fibrinolytic treatments for patients with acute RVO or for secondary prevention of the disease were eligible for inclusion in the review. Included studies had to report outcome data; specific outcomes were not defined.
More than half (60%) of the included patients had central retinal vein occlusions (CRVO); the others had branch retinal vein occlusion (BRVO). Diagnostic methods were reported. Intervention comparisons included: therapeutic doses of low-molecular-weight heparin (LMWH) and low-dose aspirin; ticlopidine and placebo; and intravenous fibrinolytic drugs followed by warfarin or aspirin, compared with haemodilution or no treatment. Time between symptom onset and treatment varied (within seven days to within 30 days). Concomitant treatments were not reported. The outcomes were visual acuity (variably defined), neovascular complications, recurrent events and bleeding complications.
Two reviewers selected studies for inclusion. Disagreements were resolved either by discussion or by involving a third reviewer.