To figure out the physical structures that carried aqueous, outflow pathway mapping was done via casting experiments. Polymerizing agents such as neoprene latex or vulcanizing silicone were injected retrogradely into distal outflow structures identified either by direct visualization or anterior filling with trypan blue . Enzymatic removal of surrounding ocular tissue resulted in beautiful branching three-dimensional casts denoting the potential AHO anatomy. These casts, in addition to histology (Figure 1), suggested that aqueous humor flowed from the anterior chamber, passed the trabecular meshwork (TM) into Schlemm’s Canal (SC) through collector channels, into an intrascleral venous plexus, and eventually to aqueous and episcleral veins . While fundamentally critical and illuminating regarding basic anatomy, casting studies were limited based on their static (non-real-time) assessments of AHO and concerns that results were non-physiologic because of high and “steady” pressure required to push polymerizing agents through the eye .