A representative electroretinogram (ERG) in a normal individual is shown in the figure above. Which retinal structure does the waveform labeled "3" in the figure correspond to?
Vitreous / Retina / Choroid
The 3rd waveform ("3") is called the "c-wave" and represents the electrical response from the RPE. The second waveform ("2"), which has a positive (upgoing) deflection, is called the "b-wave." It corresponds to the responses of the middle retinal layers containing the bipolar and Muller cells.
The negative waveform ("1") is called the "a-wave" and represents the response of the photoreceptors.