The Ishihara test for color-blindness, taken as a representative type of polychromatic tests, fails to give more than a superficial evaluation of the state of an observer’s color vision. It can be utilized as a good rough screening test for red-green color blindness, but in so doing most of the plates could be discarded. The results obtained are dependent to a large extent upon the illuminant used, and this fact militates against the deuteranomalous observer. The test gives neither an adequate qualitative (type of defect) nor quantitative (extent of defect) diagnosis, and may give a wrong diagnosis. Results obtained by this test should be discounted unless verified by other modern types of tests.
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