A Note on Polarity Potentials from the Human Eye

Abstract

Because of the renewed interest in the polarity potentials of the human eye," 2, I it seems worth while to insert in the literature records of such potentials secured by simultaneous multiple recording from four pairs of electrodes. The records here published support very conclusively the view that such potential differences arise from the polarity of the eye (negative in the back of the bulbus and positive in the front) rather than from the admitted activity of the extra-ocular muscles in turning the bulbus and in maintaining the resulting fixations. The records reveal muscle action potentials; but the great swings in potential do not arise from such a source.Small chlorided silver hat-like electrodes with an inside diameter of 5 mm. and resting on felt brims were attached to the surface of the skin by means of collodion. Contact with the skin was maintained by means of electrode jelly which was injected through a small hole in the dome of the electrode hat. The electrodes were placed as closely as possible to the eyes but over the stationary bony margins of the orbits. Four electrodes were placed about the right eye on the nasal, temporal, infra-and supra-orbital (above eyebrow) margins. In addition, an electrode was attached to the temporal margin of the left eye. Potential changes were recorded simultaneously from four paired combinations of the five electrodes as follows: (1) right temporal-right nasal (horizontal leads); (2) right infra-orbital and right supra-orbital (vertical leads); (3) right temporal-left temporal (temporal leads); and (4) right supra-orbital and right nasal (oblique leads). The method of bi-polar recording with none of the leads directly grounded was used.Four independent amplifying channels and a Westinghouse, type PA, four element oscillograph made possible the simultaneous recording from four pairs of electrodes. The amplifiers were of the push-pull type throughout and were coupled with 2 microfarad condensers and 0.5 megohm grid resistors which provided a time constant of the order of one second. Direct current potentials of the type dealt with in this study show therefore only an initial surge of the recording line with each eye movement and then a gradual drift back to the baseline. The magnitude of the potential change between any two electrodes with each sudden eye movement is represented by the initial deflection. (If one is interested in recording rapid eye movements as relatively discrete phenomena, it is perhaps better to use an amplifier with a shorter time constant. Since 0.5 and 0.1 microfarad con-180