[Evaluation of desaturated Panel D-15. III. Evaluation of the validity of the desaturated Panel D-15]

The estimation of the validity of a test refers to whether this test measures what it claims to measure. The validity of the desaturated panel D-15 was estimated in 248 subjects with congenital hereditary dyschromatopsia. The method used was based on a qualitative and quantitative study of the so-called lines of confusion joining the positions of the colored caps on the classical Farnsworth's diagram. The qualitative estimation was evaluated according to the prevailing number of lines of confusion which were parallel to a given line of reference of the diagram; it was related to the axis of the dyschromatopsia. The comparison of the results with results of Nagel's anomaloscope used as a reference test, demonstrated an overvaluation of the number of the protan subjects (anomaloscope: 77; desaturated D-15: 107) and an undervaluation of the number of deutan subjects (anomaloscope: 169; desaturated D-15: 70). This kind of discrepancy was not apparent with the standard Panel D-15. The quantitative estimation was evaluated according to the whole number of lines of confusion whatever their directions; it was related to the severity of the dyschromatopsia. The comparison of the results with the results of Nagel's anomaloscope demonstrated that the dichromatic and extreme anomalous trichromatic subjects nearly always (40 subjects out of 42) had 7 lines of confusion, or more; the simple anomalous trichromatic subjects had a variable number of lines of confusion, from 1 to 8, without any prevalence in the great majority of cases (193 subjects out of 204).(ABSTRACT TRUNCATED AT 250 WORDS)