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September 1957

Studies of the A-Wave in the Human Electroretinogram

Author Affiliations

Bethesda, Md.
Ophthalmology Branch, National Institute of Neurological Diseases and Blindness, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.

AMA Arch Ophthalmol. 1957;58(3):431-437. doi:10.1001/archopht.1957.00940010443019

The electroretinogram (ERG) in response to high-intensity stimuli represents a sequence of waves beginning with a negative deflection—the a-wave. Previous studies have analyzed this complex wave in terms of photopic and scotopic components. These analyses were derived from the behavior of the a-wave during dark adaptation and with stimuli of different wavelengths.1-4 This assumption of a duplex nature of the a-wave has been strengthened by the fact that it frequently appears to be split into two parts separated by a "step," or hump. Based on this finding, tentative schemes have been suggested in which the photopic and scotopic components of the a-wave are distinguished by different latencies.1,4

The present study deals with the a-wave of normal, congenitally night-blind, and totally color-blind subjects in response to white-light stimuli of different intensities. Since the rapid course of the a-wave prevents adequate measurements when it is registered with standard ERG techniques,

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