BACKGROUND : Colour vision is a function of the visual system and is important in visually-demanding environments
such as aviation. There is no international consensus on minimum colour vision standards or on colour vision
assessment protocols for use in aviation.
OBJECTIVE : To provide an update on colour-vision tests approved by the International Civil Aviation Organization
and to highlight the importance of choosing appropriate colour-vision tests that can be used with confidence to
detect colour-vision deficiency, to classify the type of deficiency involved, and to quantify the severity of loss.
METHODS : Available English literature was reviewed. The articles reviewed focused on the colour-vision tests
recommended by the International Civil Aviation Organization.
FINDINGS : Comparisons of conventional colour-vision tests revealed the enormous variability and inconsistency
of outcomes. Novel techniques of colour-vision assessment referred to as precision tests provide more
description of the class and severity of colour vision loss. These techniques go a long way towards
establishment of an objective and less variable colour-vision assessment within aviation.
CONCLUSION : There is a clear need for the development of an internationally recognised system of colour-vision
assessment that is less variable and can be used to accurately classify the class of colour deficiency and
severity of loss of vision. There is an even greater need to establish the level of residual colour vision that
can be classed as safe within well-defined working environments to ensure that applicants who can carry out
safety-critical, colour-related tasks, as well as normal trichomats, are not discriminated against on the basis of
their colour deficiency.