The electroretinogram of the dark-adapted eye in chronic simple glaucoma and in chronic congestive glaucoma shows that the height of the b-wave is unrelated to the degree of function of the peripheral or central retina. The retinal process responsible for the b-wave is unlikely, therefore, to be located within the optic nerve fiber layer or ganglion cell layer of the retina. It maybe located within the bipolar layer. The height of the b-wave is correlated with pupil size[long dash]the larger the pupil, the more effective the light stimulus.