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Yoshiaki Shimada; Electrooculogram artifacts in long flash electroretinogram recordings. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5027.
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© ARVO (1962-2015); The Authors (2016-present)
Electrooculgram (EOG) artifact caused by ocular dipole movement is a major noise source in electroencephalogram recordings. EOG artifact has been recognized also as one of the potentials from extraretinal sources in electroretinogram (ERG) recordings. The purpose of this study is to evaluate EOG artifacts in long flash human ERGs.
The signals from the non-stimulated fellow eye were recorded during recording of photopic ERGs elicited from the other eye of ten subjects. Three subjects had a unilateral disorder with severely reduced vision (CRAO, CRVO and optic atrophy). A pair of built-in white LED contact lens electrodes was used binocularly. While an ERG elicited by short stimuli (3 ms of 1,000 cd/m2) or long stimuli (300 ms of 100 cd/m2) was recorded from one eye, the artifact signal was recorded from the non-stimulated eye. Signals from both eyes were band-passed 0.5-1,000 Hz.
Periodic eye movements, turning eyes conjugately away under the contact lens, were observed in many subjects because of photophobia, especially with the long stimuli. One subject with the short stimuli and eight subjects with the long stimuli showed baseline drift from the non-stimulated eyes. This artifact was superimposed on the ERGs from the stimulated fellow eyes, giving the appearance of a photopic negative response (PhNR). In subjects with unilateral visual impairment, the baseline drift appeared binocularly when their healthy eyes were stimulated but stimuli on diseased eyes did not evoke the artifact.
Johnson MA et al. reported in 1982 that it is possible for a blink to become habituated, but that eye movement was not. As the initial position of the electrode was at the most positive pole of the eye, then any movements of the eye produced a negative deflection because of the standing field potential. EOG artifact was absent in an eye with poor retinal ganglion cell function, like PhNR, due to a lack of dazzle.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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