Parnaparin versus aspirin in the treatment of retinal vein occlusion. A randomized, double blind, controlled study

Retinal vein occlusion (RVO) is a common cause of unilateral visual loss. Evidence based treatment recommendations for patients with RVO cannot be made because of the lack of adequate clinical trials. To compare the efficacy and safety of aspirin and of a low molecular weight heparin, parnaparin, in the treatment of RVO.

In a multicenter, randomized, double blind, controlled trial eligible patients with a delay between symptoms onset and objective diagnosis of less than 15 days were randomized to aspirin 100 mg/day for 3 months or to a fixed daily dose of parnaparin, 12.800 IU for 7 days followed by 6.400 IU for a total of 3 months. Primary end-point of the study was the incidence of functional worsening of the eye with RVO at 6 months, as assessed by fluorescein angiography, visual acuity, and visual field. Study end-points were adjudicated by an independent committee.

Sixty-seven patients were enrolled in the study and 58 of them (28 treated with parnaparin, 30 with aspirin) were evaluable for the analysis. Baseline characteristics were well balanced between groups. Functional worsening was adjudicated in 20.7% of patients treated with parnaparin and in 59.4% of patients treated with ASA (p=0.002). Recurrent RVO was diagnosed in 3 patients, all treated with ASA (p=n.s.). Bleeding rates were similar between the two groups.

Parnaparin appears to be more effective than aspirin in preventing functional worsening in patients with RVO. The results of this study need to be confirmed in a larger clinical trial.