- Published: NHS Choices website, no date
- Authors: NHS Choices website
- Date Added: 30 Jan 2014
- Last Update: 30 Jan 2014
To provide information about colour vision.
People with colour vision deficiency are unable to see colours clearly and accurately, and may find it difficult to distinguish between different colours.
Although often called colour blindness, true colour blindness, where no colour can be seen at all, is rare.
People with colour vision deficiency may have difficulty identifying pale colours or deep colours if the lighting is poor.
Colour vision deficiency can vary in severity. Some people are unaware they have a colour deficiency until they have a colour vision test. Others will experience a very slight difference in the way they appreciate different hues and shades of colour.In rare cases, a person may experience many colours that all appear to be the same.
There are two main types of colour vision deficiency:
red-green deficiency – where people are unable to distinguish certain shades of red and green; it is the most commonly inherited type
blue-yellow deficiency – is a rare condition where it is difficult to distinguish between blue and green, and yellow may appear as a pale grey or purple
There is currently no cure for inherited colour vision deficiency because it is not possible to repair or replace the cone cells in the retina.
However, colour vision deficiency does not cause any long-term health problems.
Most people with colour vision deficiency learn to adapt to their condition, and it is usually possible to find ways to compensate for difficulty with colours. For example, it is possible to recognise the position of the lights on a traffic light, rather than the different colours.