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December 1951


Author Affiliations

Post-Doctorate Fellow, United States Public Health Service.; From the Department of Neurology and Psychiatry, New York University College of Medicine, and the Neurologic and Psychiatric Services, Bellevue Hospital.

AMA Arch Ophthalmol. 1951;46(6):625-636. doi:10.1001/archopht.1951.01700020639003

THE COMMONLY accepted theory of dark adaptation relates the threshold for light perception to the concentration of visual purple in the retina.1 The arguments that the retina is the major, if not the only, site of the dark-adaptation process are based on deductions made from measurements of dark adaptation, brightness discrimination, flicker perception, and retinal photochemistry. Little consideration has been given to the role of the central nervous system (retinogeniculocalcarine system) in dark adaptation. Attempts to analyze the dark-adaptation process into its component parts have been mainly chemical. These studies have provided a detailed knowledge of the photochemistry of the retina and a description of a mechanism capable of absorbing light energy and then releasing the energy needed to begin the train of nervous impulses. Comparison of the in vitro behavior of retinal chemical reactions and the dark-adaptation process, as measured by Hecht's method, showed that their activities were

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