The aim of this study was to evaluate the effect of PXF (1800 mg daily) in patients with sudden loss of vision (SLV) in a 4-week trial, evaluating clinical outcome and retinal flow parameters. Inclusion criteria were SLV associated with thrombosis of the retinal artery; decrease in retinal blood flow (PSF: peak-systolic flow; EDF: end-diastolic flow velocity) and asymmetry between the two retinal arteries (>40%) documented by duplex scanning. All 10 included patients completed the study. The groups were comparable. No side effects were reported. A significant improvement in flow velocity (p<0.05) and a decrease in analogue score in both groups were observed. PSF increase was 550% in the PXF group vs 288% in the placebo group (262% difference). EDF increase was 400% in the PXF group vs 200% in the placebo group (200% difference). There was a significant difference in the analogue score decrease (33.3% difference larger in the PXF group; p<0.05). In conclusion, PXF treatment improved retinal flow after retinal artery occlusion better than placebo and should be considered as an important option in this condition.