Influence of adaptation on the strength-frequency curve of human eyes, as determined with electrically produced flickering phosphenes

Abstract

The relation between the threshold intensity, as determined with the light-sensation evoked by electrical stimulation of the eyes, and the frequency of the stimulating currents was studied in varying adaptation states of the eyes. The strength-frequency curve of the light-adapted eyes has 5 minima at frequencies of 7, 20, 35, 54 and 74 c.p.s. and that of the dark-adapted eyes has 3 minima at frequencies of 7, 35 and 65 c.p.s. The two kinds of strength-frequency curves taken under light- and dark-adaptation differ from each other most greatly at 20 c.p.s., moderately about 55 c.p.s., and only slightly at 7 and 35 c.p.s. Even though a small circumscribed area of the retina is illuminated, the strength-frequency curve varies its form in various manners according to the brightness and wavelengths of light used. In general, red light of extremely long' wave-lengths has only a slight effect on the form of the curve, but blue-violet light is far more effective. It was discussed that 20 c.p.s. may be the optimum frequency for electrical stimulation of those portions of the optic organs connected to rods. © 1951, Tohoku University Medical Press. All rights reserved.