[Basic studies on the potential changes in the eyelid elicited by flash stimulation, especially related to the...

In order to establish the most adequate method to lead the photically evoked lid potential changes, their physiological properties were studied from standpoint of dark or light adaptation, which is known to be due to the increase or decrease in the sensitiveness of the retina that is the receptor of the orbicularis oculi reflex. The photically evoked lid potential changes were obtained with the summation technique by the signal processor (7 T 0 8, SAN-EI, Tokyo) in normal subjects. In addition, the average summated responses of the photically evoked lid MV responses, the ERG, EOG and EEG were also recorded simultaneously and discussed polygraphically. The results obtained were as follows: The average evoked lid potential changes in healthy resting subjects with eyes closed were shown to be composed of early rapid component, initial slow component and late slow component, which corresponded to dominant rapid vibrations of the evoked lid MV responses, the a and b waves of ERG and the EOG, respectively. The electromyographic and electrooculographic components were observed to have peak latency of about 60 msec and 200 msec, respectively. The electromyographic and electrooculographic components were found to change corresponding to the level of cortical activity indicated by the EEG patterns. They were gradually suppressed in amplitude according to the decrease of cortical activity and disappeared in stage 2 of natural sleep, although the electroretinographic components remained. With the progress of dark adaptation after adapting from light to darkness, the electromyographic and electrooculographic components in addition to the electroretinographic component of the average lid potential changes were considerably increased in amplitude but hardly changed in peak latency.(ABSTRACT TRUNCATED AT 250 WORDS)