A study of the acute phenomenons following retinal vein occlusion in rodents and in humans was performed. A three-dimensional modelling of the retinal microvasculature was performed, which allowed to propose a novel concept of the distribution of retinal flow. A novel technique for analysis of retinal blood flow based on the use of fluorescently labelled red cell and leucocytes was designed. We described the microvascular remodelling following laser-induced acute retinal vein occlusion and showed that there is elective damage to the intermediate capillary plexus. In addition, our model allowed to understand the disposition of collateral vessels. In humans, we identified a novel entity called "perivenular whitening" which is due to acute blood flow decrease leading to retinal hypoxia, a previously unrecognized feature of retinal vein occlusion.