Phenotypes of anomalous trichromacy

This paper considers the substantial variation among anomalous trichromats, even among those within a discrete subtype such as simple deuteranomalous trichromacy. First, theoretical calculations show that relatively small individual differences in wavelengths of peak sensitivity of pigments and/or in optical densities can substantially affect Rayleigh matching, which is the procedure typically used to diagnose different types of anomalous trichromacy. Second, an ensemble of colour matches is introduced as a technique to assess individual differences in peak wavelength and density. Finally, results are reported from simple deuteranomals, two of whom are shown to have pigments with different peak wavelengths and two of whom are shown to have pigments with different optical densities. We argue that the standard classifications of anomalous trichromacy are too broad to relate phenotypes to genotypes.