Effect of changes in illumination level on electro-oculography (EOG).

Abstract : Changes occur in the corneo-retinal potential of the eye when the level of ambient illumination is altered. These changes can seriously affect electro-oculographic (EOG) records, a technique frequently used for measuring nystagmus. EOG calibrations were done on seven human subjects for periods during which the illumination was varied between normal room light, red light and total darkness. The time dependence of the observed variations was established and seen to be reasonably consistent between all subjects. For purposes of EOG calibration, no difference was found between a red light environment and total darkness. When experiments are to be performed in the dark, or with eyes closed, it is strongly recommended that subjects be dark adapted for at least 50 minutes prior to calibrating and recording eye position. (Author)