Relation of Size of Electroretinogram to Rhodopsin Concentration in Normal Human Beings and one Totally Colour Blind

Abstract

THE surprising fact that during regeneration of rhodopsin in the dark after sufficient light adaptation the electroretinogram does not begin to increase in size until some 50 per cent rhodopsin has been regenerated was originally demonstrated in cats and frogs¹. Fig. 1 (open circles) shows that also in light-adapted man (three cases) there is an initial phase of very slow recovery of the b-wave of the electroretinogram in the dark, followed by a faster rise. On the suspicion that the initial delayed recovery might be due to a general suppression of rod-action on the part of the cones the experiment was repeated with a cone-blind woman. Her electroretinogram (Fig. 1, filled circles), indeed, showed Ho initial period of delay but began to rise immediately, as does regeneration of rhodopsin. It was 3 min. before the controls showed any response at all.