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L. M. Head, F. M. Almoqbel, N. K. Yadav, S. J. Leat, E. L. Irving; Parameter Optimization of Sweep Visual Evoked Potential in Children and Comparison to Adults. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3317. doi: https://doi.org/.
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The sweep visual evoked potential (sVEP) is a fast, objective method for assessing visual functions in patients with communication difficulties or children with a short attention span. When using this technique there are a variety of parameters which can be modified. However, the parameters chosen may affect the measured threshold. The purpose of this study was to determine the optimum luminance, temporal frequency, and the electrode placement for visual acuity and contrast threshold measurement in children 6 - 8 years of age and compare them to those for adults.
PowerDiva software was used to generate the stimulus and analyze the data. SVEP were measured with horizontal sinewave gratings in 10 children and 6 adults at luminance levels of 25, 50 or 100 cd/m2, temporal frequencies of 6, 7.5, or 10 Hz and with either ISCEV or PowerDiva electrode placements. A regression line to determine threshold was fitted using the following criteria: criterion 0 (C0)- regression line fitted by the software; criterion 1 (C1)- regression line fitted by eye; criterion 2 (C2)- regression line fitted from the peak amplitude to the last data point with a signal to noise ratio (SNR) >1; criterion 3 (C3)- regression line fitted from the peak amplitude to the last data point with an SNR of greater than or equal to 1, that is also within the swept range.
C0 and C1 were significantly different from C2 and C3, yielding lower visual acuity and higher contrast threshold values. For children but not adults there was a significant difference for luminance of 25 cd/m2 when spatial frequency was 1cpd. There were no significant effects of electrode placement. There were significant effects of temporal frequency when the number of viable readings was considered.
The study showed that the criteria for regression line fitting had more effect on thresholds than the other parameters, but that a higher luminance of 50 and 100 cd/m2 and temporal frequency of 7.5 Hz tend to give optimum results. Similar parameters can be used for both children and adults.
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