Figure 6: Oxygen and VEGF landscape shift following photocoagulation. Oxygen landscape shift after photocoagulation. The oxygen landscape exhibits peak tension near the arteriole and venule and trough tension near the center between these major vessels (left). Prior to capillary occlusion cells situated at the trough of oxygen tension are only slightly above the hypoxic threshold. Following capillary occlusion, the next subfigure shows the cells now fall below the hypoxia threshold and locally secrete VEGF and other factors propagating nearby capillary occlusion. Photocoagulation therapy, namely, the shortened band pattern therapy shown in the next subfigure as a green block, produces an extra oxygen peak at the center between the arteriole and venule. The additive oxygen tension from the choroid then relieves hypoxia, preventing elevation of VEGF synthesis and protecting against propagation of retinal capillary occlusion.