Components of the Human Electroretinogram. The Photopic Electroretinogram in Normal Eyes, in Deuteranopia and in Deuteranomdy

Abstract

Summary. A photopic electroretinogram (ERG) with two negative and four positive humps was recorded earlier (heck and Rendahl 1957). In the course of dark adaptation, an ERG has now been recorded which appears to contain one additional negative wave and one positive one, evidently the scotopic components. It has been found possible to suppress the various components of the ERG successively by increasing the light adaptation. On examination of six deuteranopes, an ordinary photopic ERG was obtained. On adaptation to green light, the fourth component was unaffected in two cases. A markedly decreased sensitivity to green light was observed in a similar way in three subjects with deuteranomaly (a fourth exhibited the same variations as in subjects with normal colour sense). In the four other deuteranopes, the fourth component was suppressed on adaptation to green light, exactly as in normal eyes; the sensitivity to green light was perhaps increased. On the basis of this and other investigations of colour blindness, the suggestion is put forward that the first type of deuter‐anopia is due to a lack of “green receptors” in the retina, whereas the second type is to be ascribed to the impulses from retinal receptors with different oolour sensitivity being coupled to the same nerve paths.

Stimulus Alternation and Fast Retinal Potentials: Photopic and Scotopic Contributions*

“…(2) Cobb & Morton's observation (1954) of a faster decrease of the latency of the b-wave than that of the wavelets, suggesting the presence of two different mechanisms as assumed also by Jacobson et al (1967) and by Wachtmeister (1973). (3) From observations 1 and 2 it can be concluded that the amplitude of the oscillations having a longer latency than the peak of the b-wave decreases to zero as was described by Rendahl (1958), Genest (1964), and Tsuchida et al (1973). These three observations were supported by the data of the present experiment (Fig.…”

“…Also, the waveforms of S1 and Ss were composed of lower frequencies and Se was observed on the falling slope of the b-wave. Rendahl (1958Rendahl ( , 1964 regarded the fifth wavelet as being of scotopic nature, whereas Auerbach (1964) suggested that the first three wavelets were of photopic and the fourth and fifth wavelet were of scotopic origin. According to the present results, photopic oscillations and one scotopic wavelet occurred at the same adaptation level with a considerable overlap of stimulus intensities.…”

“…In several experiments designed to control the state of adaption, oscillatory potentials in response to single flashes of light were obtained (De Molfetta et al 1968; Jacobson et al 1968; suggesting their photopic nature. The results of experiments utilizing coloured light stimuli (Alfieri & Sole 1968) and using selective adaptation (Heck & Rendahl 1957;Rendahl 1958Rendahl , 1964) indicated a close relation of the oscillations with the photopic system. Further, the fact that, in colour blind individuals no oscillations can be recorded (Heck & Rendahl 1957; ) is also in line with these conclusions.…”

The A‐wave of the Human Electroretinogram During the Course of Dark Adaptation

“…Similar phenomena, in the form of migration of wavelets, were described by Rendahl (1958) and by Auerbach (1964), although other methods were used. It is probahly a question of negative scotopic processes which, through their changes, can affect the position and nature of the second negative peak on the ERG.…”

“…Since then, it has been the subject of comprehensive studies, not least from the physiological aspect (Bornschein k Goodman 1957, Heck & Rendahl 1957, Rendahl 1958, Aoki 1960, Nagata 1962, Yonemura, Tsuzuki & Aoki 1962, Auerbach 1964, Genest 1964, Ruedemann 1965, Noell & Ruedemann 1966, Rouher, Sole & Alfieri 1966. These wavelets appear chiefly on the positive part of the ERG.…”