COLOR CONTRAST THRESHOLDS IN CONGENITAL COLOR DEFECTIVES

The influence of congenital colour defects on a clinical computer test for equiluminous colour discrimination is studied. Differences in rel ative spectral sensitivity and changes in colour contrast discriminati on are two distinct manifestations of the abnormal genes responsible f or congenital red-green defects. The very simple and rapid method of t he heterochromatic flicker brightness test acts like an anomaloscope a nd can be used to distinguish protan and deuteran defectives. The dept h of the congenital colour defect can be quantified by the colour cont rast threshold measured in equiluminous conditions along a single red- green axis identical for all types of red-green colour defectives. Col our contrast thresholds in tritan colour axes are not influenced by co ngenital red-green defects and therefore they are of extreme clinical interest to detect and quantify acquired colour defects, even in the p resence of a previously unknown congenital red-green defect.