Abstract
The scanning electron microscope was used to study the endothelium lining the trabecular wall of Schelemm's canal in 10 human eyes enucleated in treatment of choroidal melanomas. The eyes of 5 patients had been treated before enucleated with pilocarpine drops, and the remaining 5 were untreated and served as controls. In the pilocarpine-treated tissue there was an increased prominence of cellular bulges in the endothelial monolayer, and the endothelial pores were both larger and more frequent than in the untreated eyes. By the use of Poiseuille's formula it was calculated that the resistance offered by the pore system to the drainage of aqueous in the pilocarpine-treated group was approximately one-ninth of that in the control series.