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C. Rennings, B. Mazinani, P. Walter; Comparison Of Visual Evoked Potentials As Responses To Checkerboard Reversal Stimuli Versus Dartboard Pattern Reversal Stimuli Presented With A Software Based System . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1678.
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© ARVO (1962-2015); The Authors (2016-present)
To report on the utilization of dartboard pattern reversals compared to checkerboard reversals to evoke cortical potentials by means of a software based stimulus presentation system and the systems applicability in a clinical routine setting.
Checkerboard reversals appeared on a 21``planar computer monitor and the timing was controlled with a software for stimulus presentation (Presentation, Neurobehavioral Systems Vers. 0,53).The software allows for sending a TTL pulse via the parallel port (LPT 1) at the start of the appearance of each pattern.This pulse was used for triggering the signal acquisition system running on a second computer (System Plus, Micromed. VEPs were recorded with surface electrodes from O1,O2, and PZ. Checkerboard reversals as well as three different dartboard patterns were presented at a viewing distance of 87cm and 174cm.At the distance of 174cm the sizes of each checkerboard element in min of arc were 107,4',19,8' and 9,9'. The study was performed in six healthy subjects with a visual acuity of 20/20. Additionally three patients with age related macula degeneration and a reduced visual acuity to 20/60 or less were examined.
With the software based presentation of checkerboard reversals reproducible and stable waveforms could be recorded in all subjects.The answers to the checkerboard reversal stimuli were significantly different depending on the distance between patient and monitor, whereas there was no influence of the distance on the amplitudes of the stimuli evoked with dartboard patterns. The maximal amplitude was found to be decreased in a smaller distance significantly after stimulating with checkerboard reversals.After dartboard pattern stimulation of the healthy subjects the latency of the evoked potentials did not change according to the distance.For the patients with AMD a significantly prolonged latency and reduced amplitude could be measured.
The software based stimulus presentation proved to be applicable in a routine setting for VEP recordings.The dartboard pattern stimuli are a possibility to get results or visual evoked potentials independent of the distance between subject and stimulus monitor which is helpful for smaller laboratories.
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