A question of perspective: how your eyes process colour

A conversation with a client a little while ago got me thinking about colour vision, and about how much what we loosely call colour blindness can quietly shape a person’s life without them ever realising.

He told me his colour vision difference was not picked up until he was studying Chemistry at university. He remembered struggling to judge the endpoint of a titration, that moment when a solution suddenly changes colour, and more than once his flask would quietly overflow while everyone around him had already stopped.

He had managed perfectly well, of course. But I kept thinking how much smoother those years might have felt if someone had spotted it sooner.

If you have ever wondered whether you or your child sees colour a little differently, it is worth mentioning at your next eye examination. A few quick, painless checks can tell us a great deal.

What we actually mean by colour blindness

The phrase colour blind gets used a lot, but it is slightly misleading. Very few people see only black, white and grey. That kind of total colour blindness is genuinely rare.

Most people with a colour vision deficiency see a full, colourful world. They simply find certain shades harder to tell apart. They can enjoy a rainbow just like anyone else. It just looks a little different to them.

That is why optometrists and patient resources from the College of Optometrists, tend to say colour vision deficiency rather than colour blind. It is a more honest description of what is actually happening.

How your eyes turn light into colour

Tucked into the retina at the back of your eye are millions of light-sensitive cells called cones. Each cone carries a pigment that responds to either red, green or blue light.

When light enters your eye, these cones fire and send signals along the optic nerve to your brain, which blends them into the rich range of colours you see every day.

If one type of pigment is missing or behaves a little differently, certain colours become harder to separate. Reds and greens are the most commonly affected, which is why a traffic light or a colour-coded chart can sometimes cause confusion.

Why does spotting it early make such a difference?

Colour vision deficiency is usually something you are born with, and because it feels completely normal to the person who has it, it often goes unnoticed for years.

That matters most in childhood. So much early learning is colour-coded, from reading schemes to maths resources, and a child who cannot follow the colours may simply look as though they are struggling, when really they are seeing the task differently.

A simple colour vision check forms part of a thorough children’s eye examination. If we do pick something up, it is rarely a cause for worry. More often, it comes as a relief, because once a teacher knows, lessons can be adapted, and a lot of unnecessary frustration simply disappears.

If your child has never had their colour vision checked, a children’s eye examination is a gentle, friendly place to start. You are welcome to book whenever suits you.

Who it affects, and why it need not hold you back

Colour vision deficiency is passed down in a way that affects far more men than women. Around one in twelve men has some form of it, compared with roughly one in two hundred women. So if you are a woman with a colour vision deficiency, you are in rare company indeed.

It is true that a handful of careers still ask for a specific colour vision test, particularly roles in aviation, the armed forces, rail and maritime work, where reading coloured signals quickly really matters. But the old idea that it closes doors everywhere is largely out of date.

One of my favourite examples is Emerson Moser, a senior crayon moulder at Crayola. When he retired, he revealed that he had been colour blind all along. By that point, he had shaped more than 1.4 billion crayons. Clearly, it never slowed him down.

And if colour is something you enjoy playing with, you might like our guide to choosing a frame colour that suits your skin tone and hair.

When colour vision changes later in life

Almost everything so far has been about the colour vision you are born with, which stays remarkably steady across your life. Just occasionally, though, colour vision can shift as you get older, and that is worth paying attention to.

If colours that always looked normal to you start to seem washed out, or suddenly harder to tell apart, it is worth booking an eye examination. A change like this is rarely a cause for alarm, but it can occasionally be an early clue to something else, from changes in the optic nerve to conditions such as diabetes that can show up in the eye before anywhere else.

This is one of the quiet advantages of a thorough, unhurried eye test. We are not only checking how well you see. We are looking at the health of the eye itself, and small changes in colour vision are part of that bigger picture.

Frequently asked questions

Is colour blindness the same as not seeing any colour?

No. Total colour blindness, where someone sees only in shades of grey, is very rare. Most people with a colour vision deficiency see colour perfectly well but find particular shades, usually reds and greens, harder to tell apart.

Can colour vision deficiency be cured?

Inherited colour vision deficiency cannot be cured, because it comes down to how the cones in your eye are built. The good news is that most people adapt easily once they understand it, and knowing about it early makes school and work far smoother.

Should my child be tested for colour vision?

A colour vision check is a sensible part of a child’s eye examination, especially before they start school, where so much learning relies on colour. If you have any concern at all, mention it, and we will take a look.

Can colour blindness develop later in life?

Most colour blindness is inherited and present from birth, where it stays stable. Colour vision can occasionally change as you get older, though. If you notice colours looking different from how they used to, it is worth having your eyes checked, as it can sometimes point to another condition.

How is colour vision tested?

It is quick and completely painless. We usually use a simple set of patterned images, and your child only needs to tell us what they can see. There are no drops and nothing uncomfortable involved.

Colour vision is just one small part of the bigger picture of your eye health. Whether it is for you or your little one, we would be glad to take a proper, unhurried look. Book an appointment at our Belsize Park practice, where we look after families from across Hampstead, Primrose Hill and Camden, and we will take care of the rest.