Protrusions of the inner wall of Schlemm's canal.

Large specific protrusions of the trabecular meshwork into Schlemm's canal (hernias) have been suggested to be the main drainage routes for aqueous humor, similar to the function of the arachnoid villi in draining the cerebrospinal fluid. My quantitative study in cynomolgus monkeys does not support such a hypothesis. The drainage routes of the aqueous humor, evaluated from the number and sizes of the pores observed by scanning electron microscopy, were as common through the hernias as through other parts of the inner wall of Schlemm's canal at different levels of intraocular pressure. The total surface of the hernias was a small percentage of the total surface of the inner wall.