The X-Chrom lens for correction of color deficiency

Abstract

The effectiveness of the X-Chrom lens in alleviating the defective color vision of two men (a severe protanomalous trichromat and a dichromatic deuteranope) was evaluated with an extensive battery of color vision tests. The first man failed all tests except one without and with the X-Chrom lens: The second failed all tests without the lens; with the lens, he passed three tests but performed significantly poorer on two other tests. It is emphasized that color vision tests are designed to be used only under standard illumination, and that passing such tests under non-standard conditions does not signify normal color vision. These results provide no evidence that the X-Chrom lens corrects color deficiency.