Consistency of secondary colour vision tests in transport industries

Background: Occupational colour vision testing is a requirement in a number of transport industries, and there are a number of tests that are considered acceptable by the various industry regulatory bodies.

Aims: To review the occupational colour vision tests currently in use nationally and internationally and determine whether they give consistent results.

Methods: A systematic review of the evidence was carried out according to standard methods. The Ovid Medline database was searched from 1946 to March 2013 using a broad and inclusive strategy.

Results: A total of 8951 citations were identified, from which 20 papers were selected for data analysis. Of these papers, 13 of 20 assessed test sensitivity and specificity, and 11 papers measured the number, type and severity of colour vision deficiency of subjects passing the tests. Three studies also measured test repeatability. The quality of studies included was generally good. Sensitivity and specificity ranged from 64% to 100% and 88% to 100%, respectively. The studies evaluating the newer screen-based tests reported the highest sensitivity and specificity. The marked variability reported between tests and within tests can be attributed to many factors including test protocol, sample selection, test distance and time for dark adaptation.

Conclusions: There was low consistency between the colour vision tests examined. Lantern tests cannot be used to identify type or severity of colour vision deficit and, when used as a screening test for 'colour safe' status, give variable results. These results highlight the need for standardization across the transport industries.