Channelography and canalography are essentially the same technique that relies on unroofing Schlemm’s canal (SC) with introduction of the tracer (fluorescein, ICG, or trypan blue) [54–59]. The introduction can occur through local injection analogous to a viscocanulostomy surgery or through intermittent deposition from a flexible microcatheter as it is pulled through the eye during canaloplasty surgery. Such techniques have demonstrated images of AHO distinguishing ocular surface vessels associated with AHO from those that are not. While highlighting the anatomy, such approaches focus more on the potential space where aqueous humor can move. By introducing the tracer in SC, TM contributions are not considered. Also, no matter how quickly a surgeon pulls a flexible microcatheter out of the eyes 360 degrees around the limbus, it is impossible to deliver tracer simultaneously circumferentially to fairly assess segmental differences. Lastly whether the tracer is delivered at uniformly physiological pressures is unclear if the tracer is introduced while a microcatheter is actively being exited from the eye .