The role of Schlemm's canal in aqueous outflow from the human eye.

A mathematical model of Schlemm's canal is developed to simulate collapse of the canal and its effect on resistance to flow through the aqueous outflow network. Schlemm's canal is modeled as a porous, compliant channel that is held open by the trabecular meshwork. The trabecular meshwork is modeled as a series of linear springs that allow the inner wall of Schlemm's canal to deform in proportion to the local pressure drop across it. Based on comparisons between the model and results in the literature, the following tentative conclusions are reached: (1) Most of the resistance in the aqueous outflow network occurs in the inner wall of Schlemm's canal. (2) Glaucoma is not caused by a weakening of the trabecular meshwork and a resultant collapse of Schlemm's canal alone. Instead, glaucoma probably results from an increased flow resistance of the inner wall of the canal.