Photopic negative response (PhNR).

<p>Photopic single flash response waveforms illustrating the photopic negative response (PhNR) at increasing stimulus intensities (from top to the bottom in each panel) are shown in a normal subject (on the left) and the waveforms of two representative patients of the ALP (patient BCM5 in the middle) and NOP group (patient RCD307 on the right). Notice, that patients lack the PhNR in the given intensity range.