Abstract
Background
There are many parameters that may impact the thresholds obtained with sweep visually evoked potentials (sVEP), yet a number
of these parameters have not been systematically studied, and there is no recognised standard for sVEP recording. In this
study, the effects of electrode placement, temporal frequency, sweep direction, presence of a fixation target, stimulus area,
and sweep duration on visual acuity (VA) and contrast thresholds of the sVEP were investigated. Additionally, the effect of
these parameters on the number of viable threshold readings obtained from five active electrodes was investigated.
of these parameters have not been systematically studied, and there is no recognised standard for sVEP recording. In this
study, the effects of electrode placement, temporal frequency, sweep direction, presence of a fixation target, stimulus area,
and sweep duration on visual acuity (VA) and contrast thresholds of the sVEP were investigated. Additionally, the effect of
these parameters on the number of viable threshold readings obtained from five active electrodes was investigated.
Methods
Participants were six children (aged 6-8 years) and six adults (aged 17-30 years) with normal vision. Binocular sVEP VA and
contrast thresholds were measured for two electrode placements (ISCEV and PowerDiva) of five active electrodes, three temporal
frequencies (6, 7.5, and 10 Hz), two sweep directions (low to high and high to low), presence or absence of a fixation target,
three stimulus areas, and three sweep durations.
contrast thresholds were measured for two electrode placements (ISCEV and PowerDiva) of five active electrodes, three temporal
frequencies (6, 7.5, and 10 Hz), two sweep directions (low to high and high to low), presence or absence of a fixation target,
three stimulus areas, and three sweep durations.
Results
There were differences between adults and children with respect to visual acuity, the adults having better VA than the children
(p?=?0.033 in experiment 2). Overall, there were more viable readings at 7.5 Hz than at either 10 or 6 Hz (p?=?0.0014 for VA and 0.001 for contrast thresholds). The adults performed better (in terms of viable readings) with the fixation
target than without it (p?=?0.04). The smallest stimulus size used gave rise to fewer viable readings in both adults and children (p?=?0.022 for VA and 0.0001 for contrast thresholds). The other parameters (electrode placement, sweep direction and sweep
duration) did not give rise to significant differences.
(p?=?0.033 in experiment 2). Overall, there were more viable readings at 7.5 Hz than at either 10 or 6 Hz (p?=?0.0014 for VA and 0.001 for contrast thresholds). The adults performed better (in terms of viable readings) with the fixation
target than without it (p?=?0.04). The smallest stimulus size used gave rise to fewer viable readings in both adults and children (p?=?0.022 for VA and 0.0001 for contrast thresholds). The other parameters (electrode placement, sweep direction and sweep
duration) did not give rise to significant differences.
Conclusions
A temporal frequency of 7.5 Hz, a stimulus area of 4° or larger for VA and 10° or larger for contrast thresholds, and the
use of a fixation target gave more viable readings, and may be indicated for future application. Consideration of the number
of viable readings showed more differences between parameters than the actual thresholds, and it is suggested that more readings
presumably would yield more reliable threshold measurements.
use of a fixation target gave more viable readings, and may be indicated for future application. Consideration of the number
of viable readings showed more differences between parameters than the actual thresholds, and it is suggested that more readings
presumably would yield more reliable threshold measurements.
- Content Type Journal Article
- DOI 10.1007/s00417-010-1469-8
- Authors
- Fahad M. Almoqbel, School of Optometry, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
- Naveen K. Yadav, SUNY College of Optometry, 33 West 42nd Street, New York, NY 10036, USA
- Susan J. Leat, School of Optometry, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
- Liseann M. Head, School of Optometry, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
- Elizabeth L. Irving, School of Optometry, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
- Journal Graefe’s Archive for Clinical and Experimental Ophthalmology
- Online ISSN 1435-702X
- Print ISSN 0721-832X
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