Feature Article

Congenital colour vision deficiencies and their occupational consequences

Stephen J Dain



Colour is widely used to enhance the speed and accuracy of the transfer of information. In the workplace, the consequences of a colour vision deficiency range from simple embarrassment to the endangerment of lives.

Key Points

  • The most common congenital colour vision deficiencies involve the discrimination of redness–greeness, and occur in about 8% of men and 0.5% of women. The degree of severity of the deficiencies varies widely.
  • Errors in colour detection in the work place may result in minor outcomes, such as embarrassment, or major outcomes, such as fatality.
  • Sometimes a message conveyed by colour can be augmented with other indicators, such as flashing lights or patterns, to relay the same information. However, indicators without colour may take more time to observe.
  • Ishihara tests are often used in general practice: they are useful in detecting the presence of a colour vision deficiency and may diagnose the type of deficiency, but do not define the extent of the defect.
  • Determining whether a patient’s vision is ‘defective safe’ or ‘defective unsafe’ may be more important than defining the type and extent of colour vision deficiency.