THE ELECTRICAL response of the vertebrate retina to light has been the subject of physiologic research for some time past. As far back as 1865 Holmgren,1 in Sweden, was aware of these changes. Later, Dewar and McKendrick,2 working independently in Scotland, also noted this effect. The work was carried further by many outstanding investigators, but all were hampered by the lack of instruments adequate with regard to sensitivity and amplification. With the advent of the modern radio tube, rapid advances have been made in these studies and have evolved into what is presently known as electroretinography. For the outstanding contribution in this field, the reader is referred to the monograph by Granit,3 which covers all phases of the work. Recently, we completed a survey4 of clinical electroretinography in an effort to determine its use in general clinical practice. Since the method proved both feasible and accurate,