Amplitude variability of the transient visual evoked response.

The amplitude repeatability of pattern reversal visual evoked response using a 5.5 and 40' arc check was investigated in twelve subjects with each subject recording ten 64 sweep runs. The variability by visual inspection or by analysis of variance suggests that a single run will provide a representative amplitude for a 40' arc check whereas the 5.5' check will require more runs merged together before the amplitude is stable. The larger spread of error encountered with the 40' arc check may point to a visual component contributing to more amplitude variability. The possibility of making some assessment of the level of noise present during recording is discussed.