FIGURE 11.

Depiction of the trabecular meshwork, Schlemm’s canal, and valve-like structure’s pressure-dependent relationships. Images (A,D,G) depict intraocular pressure (IOP) below a homeostatic setpoint, (B,E,H) at the setpoint, and (C,F,I) above the setpoint. In this provisional model, aqueous passes through the trabecular meshwork (TM) to the juxtacanalicular region (JCR) and then flows through Schlemm’s canal (SC) inlet valves (SIV) into the SC lumen at collector channel entrances or ostia (CCO) present at the SC external wall (EW). An SC outlet valve (SOV) consists of a mobile flap-like septum between SC and a circumferentially oriented deep intrascleral vascular plexus (CDSP). The SOV act as mobile flaps or leaflets at CCO. SIV connections to the TM provide a mechanism for pressure-dependent TM motion to control CCO dimensions. The SIV are oriented circumferentially in SC so that an intraocular pressure (IOP) increase that forces the TM into SC pulls the SOV open. The central column (B,E,H) depicts an IOP of 16 mm Hg as the optimal setpoint. An IOP of 14, below the setpoint, closes the CCO and SOV, while an IOP of 18 more widely opens them, providing a mechanical IOP-dependent control mechanism. The proposed model is based on verifiable evidence of SIV, SOV, and their motion in human eyes. However, the proposed regulatory mechanism is provisional, and its premises are subject to modification or rejection as new evidence emerges Supplementary Video S4.