We record the electroretinogram from the human eye in response to flashes of light delivered at various times after exposure of the eye to very intense illumination that “bleaches” a proportion of the visual pigment. The stimuli can be designed to elicit responses from cones, from rods, or from rod bipolar cells. We have shown that the characteristic dark adaptation behaviour of the overall human visual is present even at the first synapse: at the level of retinal rod bipolar cells. This research has been undertaken by Drs Allison Cameron. In parallel, we record the recovery of the overall human visual system from the same stimuli, and we determine the extent to which human visual dark adaptation is regulated by changes at different levels within the retina. This research has been undertaken by Dr Rasa Rusekaite.