slow recruitment rate

Retinal vein occlusion (RVO) is the second commonest retinal disease after diabetic retinopathy, and is a common cause of unilateral visual loss. There are two aims in the management of RVO: the identification of modifiable risk factors and their medical management and the recognition and management of sight-threatening complications. The management of the disease includes laser therapy and the control of systemic associated diseases. Many other treatments have been proposed but there is no evidence on their efficacy in modulating the outcome of branch or central RVO. There are currently no adequate clinical trials that have evaluated the efficacy and safety of antithrombotic agents in this setting. Antiplatelet agents are frequently used in clinical practice. Anticoagulant drugs, either heparins or coumarins, are also used in this setting as they represent the first line therapy for the treatment of venous thromboembolism. Aim of this randomized controlled study is to to compare the efficacy and safety of aspirin and of a low molecular weight heparin, parnaparin, in the treatment of RVO. Study treatment is administered for 3 months. Primary end-point of the study is the incidence of functional worsening of the eye with RVO at 6 months. Secondary efficacy outcomes are the following: proportion of cases requiring laser treatment because of the extension of the ischemic lesion and/or the presence of neovascularisation and/or macular oedema, incidence of recurrent RVO objectively documented by fluorescein angiography. Safety outcomes are defined by the incidence of major and minor bleeding events.

Inclusion Criteria:

• Age between 18 and 85 years
• A body weight of greater than 50 Kg
• A requirement that no more than 15 days had passed between symptomatic presentation, confirmation of RVO and entry into the study.

Exclusion Criteria:

• Modification of the optic media transparency that could compromise the evaluation of fluorescein angiography, such as cataract or corneal degeneration
• History of major ocular surgery (with the exclusion of cataract extraction)
• Previous RVO
• Other ocular conditions that, in the opinion of the investigator, could have affected macular edema or altered visual acuity during the course of the study - Contraindications to the study drugs (e.g. major bleeding or neurosurgical procedures in the previous 3 months, serum creatinine levels of greater than 2.0 mg/dL, severe liver insufficiency, platelet count < 100,000 mm3, known active peptic gastric ulcer)
• Active malignancy
• Pregnancy
• Inability to attend for follow up or anticipated non-compliance
• Ongoing treatment with aspirin or anticoagulant drugs at the time of RVO diagnosis