Timing of the electroretinogram response and dark adaptation.

The time response of the Electroretinogram (ERG) is an essential part of the examination. Peak time of response increases with dark adaptation and decreases with the intensity of stimulation. When working with constant amplitude during dark adaptation sensitivity increases but the intensity of stimulation decreases. It is essential to clarify the relationship of these two factors for valid interpretation of results. The present work suggests that the state of adaptation or retinal sensitivity affects amplitude, while peak time of the response is modified by the absolute value of the stimulating source whatever the state of adaptation. This observation has been done on rod responses and is valid as long as pigments remain unbleached and able to respond.