The standing potential of the human eye reflects differences between upper and lower retinal areas

In 12 healthy subjects the "light peak" of the electrooculogram was measured following localized stimulation of various retinal locations. Significant differences in "light peak" amplitudes were found between central and peripheral stimulation, and at 10 deg eccentricity the "light peak" amplitudes were significantly larger following upper retinal stimulation than those elicited by lower retinal stimuli. In addition, the "light peak" amplitude produced by upper or lower retinal stimulation behaved differently when test light intensity increased. The upper retinal areas showed consistently a higher sensitivity to light intensity changes than the lower retinal areas. The "light peak" of the EOG is believed to index the rate of retinal metabolism elicited by light stimuli. Our findings show that upper retinal areas display a higher level of light-induced activity reflecting the interaction between the photoreceptors and the retinal pigment epithelium than lower retinal areas. The results are interpreted as a superiority of the upper over the lower retina and are related to other electrophysiological and functional differences between upper and lower retinal areas of man.