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

The average photically evoked lid potential changes are known to consist of electromyographic components due to the orbicularis oculi reflex, electroretinographic and electrooculographic components, which corresponded to the average summating responses of the lid MV responses, electroretinogram (ERG), electrooculogram (EOG), respectively. In the present study the photically evoked lid potential changes were studied from the standpoint of the stimulus strength in healthy subjects and patients with an artificial eyeball. The photically evoked lid potential changes were obtained with the summation technique under various physiologic and pathologic conditions. In addition, the average summating responses of the lid MV responses, EOG, ERG and EEG were also recorded simultaneously and discussed polygraphically. The average evoked lid potential changes in healthy resting subject with eyes closed were shown to be composed of the electromyographic components dependent on the effector activity of the orbicularis oculi reflex, early and late slow components which corresponded to the ERG and the EOG respectively. The threshold stimulus necessary to elicit the electroretinographic, electromyographic and electrooculographic components was the intensity of flash stimulation, that is about 0.1, 0.3 and 4 joule in energy delivered to the stroboscope respectively. These components were observed to be increased in amplitude gradually according to the intensity strengthened. In the average lid potential changes obtained by random flash stimulation to a single eye, the electroretinographic components in the occluded side disappeared completely, but the other components were clearly observed and gradually increased in amplitude according to the intensity strengthened, although they were considerably decreased in amplitude than those obtained in the contralateral side of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)