Changes in Corneal DC-potentials Associated with Changes in Pupillary Diameter

Using light-emitting diodes we stimulated monocularly with light intensities of between 7.5 and 1,800 cd/m2, and recorded simultaneously the Dc-electroretinogram and pupillary movements of the stimulated and the contralateral eye. In some investigations, the visual evoked potential and the activity from the periorbicular muscles were also recorded. Various drugs acting on the autonomous nervous system were topically applied and their efforts studied. In the eye with an untreated pupil, stimulated or contralateral, a corneo positive potential coincident with pupillary constriction was seen (cu-wave), provided the pupil was large beforehand, a corneonegative deflection dominated, which was also coincident with pupillary constriction (mu-wave). Parasympathicolytics or -mimetics abolished both the cu and mu-wave. We conclude that the cu-wave is related to depolarization of the sphincter pupillae during constriction, whereas the mu-wave might be related to a modification of the potential distribution between the pigment epithelium and the tissue surrounding the eye in the case where the pupil is constricted beyond a critical point.