top of page

Seeing things differently

In the late 18th century, a scientist called John Dalton published a ground-breaking paper called “Extraordinary facts relating to the vision of colours”.

It was the first time anyone had identified the concept of colour blindness – when a person’s eyes cannot correctly identify certain colours.

Dalton’s paper was especially impressive as it is difficult to self-diagnose colour blindness. Our optometrists can ensure your eyes distinguish the three primary colours of red, green and blue properly.

When your colour vision is normal, it is described as trichromatic – tri meaning three, and chrome from the Greek word for colour. Most people who have a colour blindness can still ‘see’ colours; they just appreciate them differently. In this example someone with normal colour vision will see the number "74", but someone with a red-green colour vision anomaly will see the number "21".

The most common form of colour vision anomaly is ‘red-green colour blindness’ – this can take on different forms. People who are affected by this will confuse colours which contain red or green – this may include brown, purple, pink and orange. Protanomaly describes reduced sensitivity to reds, deutanomaly relates to greens and tritanomaly represents blues. Tritanomaly is very rare and usually is acquired later in life. Protanomaly and deutanomaly are usually inherited traits on the X chromosome. It is thought that 1 in 12 men will have a colour vision anomaly, whereas only 1 in 200 women will.

Further information can be found at:

Our optometrists can carry out simple pattern tests during a child’s examination. If an issue is highlighted, schools can usually tailor lessons around a student’s specific needs, and bright lighting helps at any age. And while a few careers require trichromacy (such as the police, decorators and electricians), even monochromatic patients can enjoy life to the full as this is the only way they've ever seen the world.

49 views0 comments

Recent Posts

See All


Post: Blog2_Post
bottom of page