The drainage of aqueous humor n human eyes more than SO per cent of the aqueous humor seems to be drained from the anterior chamber through the chamber angle tissue into the canal of Schlemm. This in turn is drained by collector channels into the veins of the episclera and conjunctiva. There is general agreement that a rise in the resistance in the outflow routes via Schlemm's canal is the basis for most cases of open-angle glaucoma. Discussions about the pathogenesis of this disease are hampered by the fact that there is no complete agreement on the normal anatomy of the outflow routes and the mechanism for aqueous humor drainage. The purpose of this editorial is to discuss some recent studies in this field, to analyze whether there is a need for a large pore system for aqueous humor drainage into the canal of Schlemm, and to speculate about the genesis of openangle glaucoma.