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December 1979

The Chromaticity Circle-Reply

Author Affiliations

Bethesda, Md

Arch Ophthalmol. 1979;97(12):2398. doi:10.1001/archopht.1979.01020020603024

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In Reply  —Newton's color circle predicted a fixed relationship between various colors, their mixtures, and spectral perception. By eliminating Newton's center of gravity factor, the chromatogram simplifies and implements these principles in a mapping of chromaticity thresholds that is symmetrical for normal trichromats and eccentric for subjects with abnormal color discrimination. By independently varying hue and saturation, we obtain raw data that is characteristic for any type and degree of color defect, and is immediately understandable and meaningful. As Dr Moreland indicates, these data could be translated into Commission Internationale de l'Eclairage terms, but most clinicians would prefer the simpler language.The red sector defect we mentioned appears to be related to a stage in juvenile multiple sclerosis rather than a congenital color defect. Many of the other acquired defects are quite bizarre and often unpredictable, and even the congenital defects do not exactly follow the conventional definitions. We attribute

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