Congenital dyschromatopsia and school achievement.

In 1993-94, in Liguria (a northwestern Italian region) a study was carried out on dyschromatopsia, a congenital sex-linked form of colour blindness. 3124 junior high school boys aged 10-15 years were tested using Ishihara plates (1973 edition) and Farnsworth's D-15 test (1947 edition). 152 students were identified as colour blind (4.87%), a value slightly below the Italian average of 5.3%. The school achievement of these students was assessed by means of the school marks of two randomised subsamples composed of 82 dyschromates and 82 orthochromates, paired homogeneously by age and class. Statistical analysis indicated significantly lower general school achievement for the 82 dyschromate subjects (except for art). The learning difficulties of dyschromate persons for whom colour is a basic didactic tool are discussed. Introduction of dyschromatopsia tests at preschool would be desirable.