The (±) reference in pattern electroretinogram recording

: In this communication, the value of using a simultaneously acquired estimate of background noise, the (+/-) reference, is demonstrated in pattern electroretinogram (PERG) recording. During the signal averaging process, the (+/-) reference inverts the polarity of every other sweep; cycle-locked (stimulus-related) activity is thus cancelled out, leaving a noise distribution similar in statistical properties to that of the signal average. Assessing the presence of a PERG response by comparing the spectrum analysis of the PERG trace with that of the (+/-) reference is discussed. The results of the normal controls and patient groups are summarized and the raw waveforms from a representative normal observer and a patient with optic nerve damage are analyzed.