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. Author manuscript; available in PMC: 2013 Jul 10.
Published in final edited form as: Doc Ophthalmol. 2008 Aug 1;118(2):155–162. doi: 10.1007/s10633-008-9143-8

Fig. 1.

Fig. 1

The steady-state PERG is recorded from skin electrodes in response to fine horizontal bars reversing 16.28 times per second. The pattern stimulus covers a circular area of 25 degrees diameter centered on the fovea. A normal PERG waveform has a sinusoidal-like shape (green tracing) that is automatically analyzed in its amplitude and phase. Amplitude and phase are also expressed as SD deviations from age-predicted normal values. The red tracing is an example of abnormal PERG in glaucoma. Note the reduced amplitude and the delayed phase