Colour vision problems

Abstract

I read with interest the correspondence from Jayakrishnan and Al-Rawas on the use of universal dots to colour code and identify asthma inhalers.1 I appreciate the authors’ desire to ensure a universal and consistent system but, unfortunately, the interpretation of colours is fraught with complication. The problem of colour vision deficiency has been known since John Dalton first described the condition in 1798.2 Some 8% of men and 0.5% of women have some degree of a problem, that is an estimated 2.4 million men in the UK alone. Red–green colour vision deficiency is the most common and brown is a colour where particular difficulty is encountered. The problems with colour vision deficiency have been documented but continue to be generally under-appreciated in the medical environment, for example, there is good evidence that doctors and patients can struggle to spot red rashes.3 Those with colour vision deficiency can also fail to recognise blood in bodily fluids4 and this has translated into evidence that those with colour vision deficiencies are more likely to present with late stage bladder cancer.5 I would plead the case on behalf of those of us who are colour blind and I would resist the use of colour in the identification of medicines. In the diagram1 I was unable to differentiate between the brown, green, or red universal dots. It is particularly challenging to identify small dots or bands of colour, and great care needs to be taken in assigning surface colour codes as those with colour vision deficiencies are prone to error, particularly under lower levels of illumination.6