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H. Arvind, A. Klistorner, S.L. Graham, J.R. Grigg; Multifocal Visual Evoked Responses To Dichoptic Stimulation Using Virtual Reality Goggles . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1680.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the possibility of simultaneously recording multifocal visual evoked potentials(mfVEP) for both eyes with dichoptic stimulation using virtual reality goggles and to determine the stimulus characteristics that yield maximum amplitude on dichoptic stimulation.
10 healthy volunteers were recruited. Virtual reality goggles (nVisor SX, NVIS, Reston, Virginia, USA) were used to provide simultaneous stimulus display to both eyes. Displays to each eye were arranged within a cortically scaled dartboard with 32 test segments arranged in 3 concentric rings. Slow pattern onset stimuli were presented dichoptically. Experiment 1 involved recording responses to dichoptically presented (black and white) checkerboard stimuli and also confirming true topographic representation by switching off specific segments – 8 superotemporal segments for the left eye and 8 inferotemporal segments for the right eye. Experiment 2 involved monocular stimulation of the left eye and comparison of amplitude with Experiment 1 for the same eye. In Experiment 3, orthogonally oriented gratings were dichoptically presented. Experiment 4 involved dichoptic presentation of checkerboard stimuli at different levels of temporal sparseness (5.56 times/second, 2.78 times/second, 1.85 times/second and 1.39 times/second), where stimulation of corresponding segments of 2 eyes were separated by 15, 60,105 & 150 milliseconds (ms) respectively.
Experiment 1 demonstrated good traces in all regions and confirmed true topographic representation. Experiment 2 demonstrated suppression of amplitude of responses to dichoptic stimulation by 17.9±5.4% compared to monocular stimulation. Experiment 3 demonstrated similar suppression between orthogonal and checkerboard stimuli (p= 0.08). Experiment 4 demonstrated maximum amplitude and least suppression (4.8%) with stimulation at 1.39 times/second with 150 ms separation between eyes.
It is possible to record mfVEP for both eyes during dichoptic stimulation using virtual reality goggles. Interocular suppression can be almost eliminated by using a temporally sparse stimulus of 1.39 times/second with a separation of 150ms between stimulation of corresponding segments of the 2 eyes.
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