Does defective colour vision really matter?

Abstract

It has been accepted that defective colour vision is an occupational handicap since Wilson observed the high prevalence of defective colour vision among his students and wrote, in 1855, about the dangers ‘attending the present system of railway and marine coloured signals’. Standards for colour vision were introduced for the maritime and railroad transport in the 1870s and for aviation in 1919. Colour vision standards for drivers of motor vehicles have not been widely adopted and never effectively, and there is no accepted system of standards for that wide gamut of occupations that involve colour recognition, colour discrimination or aesthetic judgment of colour. The recent emergence of the concept of equal employment opportunity to prevent unjustified exclusion of the handicapped from employment and the advocacy of an articulate group of people with defective colour vision who do not wish to be excluded from their choice of occupation has weakened some existing standards. Yet there is an impressive body of evidence to show that colour figures importantly in many occupations and that some of those with defective colour vision will perform less effectively in those occupations because of their defect. There is also evidence that those with defective colour vision have a range of difficulties in everyday life, although this has been studied surprisingly little in the last 125 years. There are accident data to suggest that defective colour vision is a risk factor, but accident data are always uncertain and in weighing up the extent to which defective colour vision is a risk factor more credence has been given to the uncertainty of the data than to the indications of risk. There is a need for better definition of colour vision standards and of test protocols and for international advocacy and acceptance of the standards. A schema of colour vision standards and test procedures is proposed.