Multifocal visual evoked potentials--a method study of responses from small sectors of the visual field.

OBJECTIVE

A method study of the mfVEP technique to establish a standardised way to identify stable response components from small areas in all parts of the visual field and a test-retest reliability study.

METHODS

MfVEP was recorded from 26 healthy volunteers.

RESULTS

Two response components could be clearly identified. The latencies corresponded to those of the traditional VEP response (N75 and P100). The visual field was divided into 12 sectors. A characteristic pattern was obtained. Component I was mainly negative in the upper sectors and positive in the lower sectors. Component II was positive in the upper sectors and negative in the lower ones. Most of the sectors with missing responses were the ones adjacent to the horizontal meridian, corresponding to the phase reversals. In a test-retest reliability study, the amplitude and latency measurements of the second test were plotted against those of the first test. Correlation coefficients between 0.84 and 0.93 were obtained.

CONCLUSIONS

The mfVEP allows a reliable quantification of two response components from small parts of the visual field.

SIGNIFICANCE

This paper suggests that mfVEP could be a valuable supplement to the traditional VEP for exploring restricted parts of the visual pathways.