Effect of oculomotor nerve stimulation on outflow facility and pupil diameter in a monkey (Cercopithecus ethiops).

Aqueous humor outflow resistance was studied in monkeys (Cercopithecus ethiops) with intact oculomotor nerves, after the nerve had been severed on one side, and during electrical stimulation of the severed nerve. Pupil diameters (on both eyes) and outflow resistance on the non-stimulated side acted as controls. It was found that the outflow resistance increased and the pupil dilated when the nerve was cut. During stimulation with 2 per second and 20 per second the pupil constricted and outflow resistance decreased, especially so with the high stimulation frequency. Thus in the oculomotor nerve of the monkey there are fibers present which facilitate aqueous humor outflow.