The Steady Polarity Potential of the Human Eye

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Abstract
A steady potential from the eyeball can be isolated for measurement from the potentials of the skin and surrounding tissue by making use of the eye''s motility. The measurable ocular polarity-potential of the human eye in situ is in the order of 1 millivolt when the eye rotates laterally 30 degrees from the primary line of regard; the range found between supposedly normal subjects is from about 0.3 to 2.5 millivolts. The potential can be measured, without discomfort to the subject, by means of small metal foil electrodes placed on the skin near the eye, and connected to a vacuum tube microvoltmeter used as input for a string galvanometer. The potential exhibited by the eyeball is closely proportional to the sine of the angle of rotation of the eye. Deflections registering the steady polarity-potential of the eye show no evidence of action currents from the extraocular muscles, but do frequently show action current spikes from voluntary and reflex winking. Subjects suffering enucleation of one eye show only a very slight potential around the glass eye, and this potential appears to be a spread from the active eye. The results from measuring each eye separately when both are in place and active are probably not greatly in error through mutual electrical influence. The 2 eyes do not register equal potentials in most cases thus far examined. The potentials of the eyes can be measured in parallel but not in series in the same person. The potential of one eye may be made to oppose that of the other eye and partly to neutralize it. When both eyes are active electrodes placed on the temples ordinarily give a higher potential than do those from any other placement on the skin. 15 young normal subjects show the presence of certain simple relationships existing between the lateral measurement leads and the ascertained potentials. These relationships may be reduced to simple equations indicating equivalence of certain combinations of leads. The eyeballs and their orbital and interorbital tissues act, at least under conditions of minimal current drainage, as one homogeneous bioelectrical field.

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