Colour blindness

Around one in 12 men and one in 200 women has some sort of problem with their colour vision.

Light entering the eye consists of many different wavelengths. The light is absorbed by tiny cells at the back of the eye called cones.

In the normal eye there are three different types of cones. Some cones are best at capturing long wavelength (red) light. Others catch medium wavelength (green) light, while other cones respond best to short wavelength (blue) light. The signals from these cones are sent to the brain where they are perceived as colour.

Some people are born with one or more cone types absent or different. This can lead to difficulties differentiating between certain combinations of colours. These colour vision deficiencies can be detected and graded using various colour vision tests.

If you suspect that your child has a colour-vision problem, or if there is a family history of colour-vision problems, ask your optometrist about it. There is no cure, but you can tell your child’s teachers, so that they use colours appropriately.

The video below should be viewed in conjunction with the text beneath it and preferably watched while your optometrist discusses it with you.

Get Adobe Flash player

  • Light entering the eye consists of many different wavelengths.
  • The light is absorbed by tiny cells at the back of the eye called cones.
  • In a normal eye there are three different types of cones.
  • Some cones are best at capturing long wavelength (red) light.
  • Other cones catch medium wavelength (green) light …
  • … while other cones respond best to short wavelength (blue) light.
  • The signals from these cones are sent to the brain where they are perceived as colour.
  • Some people are born with one or more cone types absent or “different”.
  • This can lead to difficulties differentiating between certain combinations of colours.
  • Colour vision deficiencies can be detected and graded using various colour vision tests.

Lantern test

Some organisations which require the correct recognition of coloured signals (principally transport groups such as the Civil Aviation Authority, railways, maritime, naval and air force) depend upon a standard lantern test which imitates actual signal systems. Their use is confined to the trade task of recognition of coloured lights, principally red, green, yellow and white. Lantern tests require the naming of standardised coloured lights of controlled luminance, colour and size, usually in a dark room.

This is not a test that is usually done in community optometric practice, but some of the optometric universities provide this test. It is therefore suggested that if you want to have this test done you contact one of the numbers below and ask for further details:

Contact details

 

Aston University Optometry Clinic Reception
0121 204 3900
Cardiff University Eye clinic
02920 874357
City University Colour vision clinic
020 7040 0262
j.birch@city.ac.uk
Glasgow Caledonian University  Eye clinic
0141 331 3377
eyeclinic@gcu.ac.uk
University of Manchester 0161 306 3860