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Abstract
The synchronous detector technique is described for recording electroretinograms (ERG) with particular reference to separation of rod and cone function. Thus rod function is emphasized by using blue stimuli at rates of 5 to 17 cycles per second, with a darkened background. The basic principles of signal detection are the same as have been described for measurement of cone function, when white-flash stimuli are used at frequencies of 17 to 60 cycles per second, with normal background illumination. The results are of markedly different character, however, with an average rod delay time which is longer (average 61 msec.) than the average cone delay time (24 msec). The results are compared with the conventional averaged waveform ERG presentation in normal subjects and in subjects icith achromatopsia and retinitis pigmentosa.