 Retinal nonperfusion has known to be associated with the production of vascular endothelial factor VEGF. Recently, Campochiaro et al reported that neutralization of VEGF using ranibizumab improved macular edema and reversed the worsening of retinal nonperfusion in patients with retinal vein occlusion and diabetic macular edema. The precise mechanism for improved perfusion in the VEGF treated eye is uncertain. The authors suggested that VEGF exacerbates retinal ischemia by increasing leukostasis, and intravitreal anti-VEGF agents may break the feedback loop, allowing reperfusion to occur. There might be a portion of circulation that is closed but not permanently, and this reversible closure is modulated by VEGF. 