Toward a new classification of RVOs?

The proteiform features of RVO challenges classification. The discovery of patients with abrupt visual loss due to severe hypoperfusion, manifesting by perivenular whitening (PVW) in the absence of nonperfusion, raises the question of the pertinence of the ischemic versus nonischemic classification. High resolution OCT showed that focal ischemia in these cases was restricted to the inner nuclear layer, the atrophy of which accounted for clinical sequelaes. On the opposite, there are evidence that most cases of chronic macular edema are preceded by weeks or months of progressive venous dilation, hence raising the question of the true duration of the disease. Finally, we evidenced that venous macroaneurysms are a frequent consequence of longstanding RVO, whose identification by ICG angiography and subsequent photocoagulation may improve visual outcome. We will propose here a novel classification of retinal vein occlusions taking into account these features.