Korean J Ophthalmol.  2011 Oct;25(5):334-340. 10.3341/kjo.2011.25.5.334.

Study for Analysis of the Multifocal Visual Evoked Potential

• Park S
• Park SH
• Chang JH
• Ohn YH

• KMID: 1098636
• DOI: http://doi.org/10.3341/kjo.2011.25.5.334

Abstract

PURPOSE
To introduce the clinical utility of the absolute value of the reconstructed waveform method in the analysis of multifocal visual evoked potential (mfVEP).
METHODS
The mfVEP with 4-channel recording was performed using RETIscan(R) on 10 eyes of 10 normal subjects. Amplitudes were obtained from ring-shaped 6 areas and 4 sectors. The best visual evoked potential (VEP) response method and the absolute value of the reconstructed waveform method were compared in terms of analysis of the amplitudes. In order to assess the false positive rate of the examination, stimuli were administered with one-half of the cathode ray tube (CRT) monitor completely covered and the results were compared using 2 methods.
RESULTS
The amplitudes in 6 areas and 4 sectors analyzed with the best VEP response method and the absolute value of the reconstructed waveform method showed no statistical difference (p > 0.05). The amplitude in the stimuli-blocked area of the absolute value of the reconstructed waveform method was smaller than that of the best VEP response method (p < 0.05) and the amplitude of the stimuli area showed no substantial difference between two methods (p > 0.05).
CONCLUSIONS
The absolute value of the reconstructed waveform method has similar reproducibility and lower level of false positives relative to the best VEP response method. Therefore, it can be considered as a useful method in the analysis of the mfVEP.

Keyword

Absolute value of the reconstructed waveform method; Best visual evoked potential response method; Multifocal visual evoked potential

MeSH Terms

Adult
Automatic Data Processing
Evoked Potentials, Visual/*physiology
Female
Follow-Up Studies
Humans
Male
Reference Values
Reproducibility of Results
Retina/*physiology
Retrospective Studies
*Visual Fields

Figure

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  Fig. 1 The schematic representation of multifocal visual evoked stimulus. Each of the 60 sectors of the display is an independent stimulus with 16 checks, 8 black and 8 white.

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  Fig. 2 The positions of four active electrodes (A-D) and inion (red circle) and the configuration of the four channels of recording of the multifocal visual evoked potential.

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  Fig. 3 The schematic representation of the absolute value of the reconstructed waveform method. A midline channel is reconstructed as the difference between channel 1 and channel 4. A horizontal channel is reconstructed as the difference between channel 2 and channel 3. The positions of the four active electrodes (A-D) are shown.

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  Fig. 4 Areas 1 to 6 according to the distance from the foveal center are represented in the schematic diagram.

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  Fig. 5 Sectors 1 to 4 as determined by the horizontal meridian are represented in the schematic diagram.

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  Fig. 6 The schematic representation of cathode ray tube (CRT) monitor with nasal side covered completely. Stimuli were administered with one-half of the CRT monitor covered completely to stimulate the temporal retina of right eye to determine the false positives of the examination.

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  Fig. 7 The mean amplitude analyzed by the absolute value of the reconstructed waveform method (B) in the stimuli-blocked area was smaller than that by the best visual evoked potential response method (A).

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  Fig. 8 A schematic diagram for determining the orientation of a dipole. Each circle indicates the location of an electrode. α is angle between a dipole and the midline channel. Cos α is obtained from the coefficient from the midline channel and sin α is obtained from the coefficient from the lateral channel.

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  Fig. 9 Waveforms of the visual evoked potential (VEP) response in two methods: waveform (A) analyzed by the best VEP response method and waveform (B) analyzed by the absolute value of the reconstructed waveform method showing the positive deflection.

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