Previous studies demonstrated that the (+) isomer of aceclidine has a stronger cholinergic effect than pilocarpine or the racemic mixture of aceclidine. The effect of aceclidine(+) and pilocarpine on the intraocular pressure and the sphincter pupillae in patients suffering from open angle glaucoma, and on the accommodation in normal young subjects, was studied. The results demonstrated a similar effect of both drugs. The discrepancy between the cholinergic potential of the drugs and their effect in the eye is discussed.