Colour blindness for the Uninitiated

My 5 year old has an eye test at school today, so at some point I'll get a call from the school nurse to tell me that he's colour blind. I already know, I spotted it when he was very young because I've been here before. My 16 year old son is also colour blind (colour vision deficient).

I have always been around colour blind people. My brother, Grandfather and other male relatives were colour blind. My ex (of 15 years) is also colour blind, and my partner's father. This post hopes to answer some of your questions regarding the most common type of colour deficiency - Red-Green Colour Blindness. An inability to fully see red or green.

 Why are people colour-blind?

Inside the eye are cones which 'see' the different wavelengths of light. Some see red, some blue, some green. When these are faulty or fail to pass on the messages correctly to your brain, you have colour deficiency.

There are several reasons why people are colour-blind from birth, but by far the most common is heredity. You get it from your parents.

Red-green colour-blindness is carried in the X chromosone. Men have 1 X chromosone and 1 Y. Women have 2 X chromosones. So a man only needs one faulty chromosone to be colour-blind. Boys get their X chromosone from their Mum, girls get one from each parent (sperm are either Y or X, male or female).

A colour blind man will always pass on his faulty X chromosone to his daughters.

A man cannot pass on colour blindness to his sons because he doesn't give them an X chromosone. 

As a woman who has 1 faulty X chromosone, I am a carrier, but I am not colour-blind myself because of my other normal X chromosone. As I give an X chromosone to all of my children, my sons have a 50% chance of being colour blind. My daughters have a 50% chance of being a carrier. If my partner is colour-blind then my daughters have a 50% chance of being colour blind and will be a carrier.

For a female to be colour blind she has to receive the faulty chromosone from both parents, so her Mother has to be a carrier or colour-blind and her Father colour-blind for her to receive 2 faulty X chromosones. In turn all of a colour blind woman's boys will be colour-blind and all of her daughters will be carriers or colour-blind.

You still with me?

Blue colour blindness occurs equally in men and women, is caused by chromosones that are not gender related and is relatively uncommon.

Inherited colour blindness will not improve over time. You will always be colour blind.

Colour blindness isn't necessarily 'on or off', it is a scale, so even though you may be green deficient, you might still be able to see some green.

How does my colour blind child see the world?

Colour blindness in most people is a failure to see green or red and it can be complete or partial. This doesn't mean that their world is grey at all, it means that it's just very different to what people with full colour vision see.

Here's a family you'll recognise from my Lego Simpsons House posts to show the differences in vision. If you have normal colour vision then the red and green colour blindness pictures will look very similar, however if you are colour-blind then they're actually slightly easier to tell apart - and colour blind people will also usually be able to tell you the colours in the photo's, whereas you can't! 

Please bear in mind that different screens will show these photo's differently, so they are just examples.

Normal colour vision

Mild Green Colour Blindess - Deuteranomaly

Green Colour Blindness - Deuteranopia

Mild Red Colour Blindness - Protanomaly

Red Colour Blindness - Protanopia

Blue Colour Blindness - Tritanopia

How can I tell if my child is colour blind? 

Colour blindness tests are notoriously hard to administer with very young children. Previously my 5 year old has passed tests, and then failed red and green vision tests, it's only now that he's consistently failing to see green, as does his older brother, that we can be fairly confident that's his true diagnosis.

When you teach a child colour names, they learn with whatever vision they have, so they may well get the colours right most times, but it's their version of what 'green' is. I first spotted my 5 year old had colour vision problems when he was very young because when he was learning colours he would consistently get the same ones wrong in specific books or with certain toys. Different hues and shades of colours are very important.

Getting colours wrong is a normal part of learning, and it really isn't until a child is 3 or 4 that you can say with any degree of certainty that they are not just still uncertain.  When they are tired or disinterested then they will make more mistakes than when they are enthusiastic, and they might just prefer to use certain colours!

In my experience some of the more obvious signs that your child has a colour vision deficiency are green Santa Claus colourings, confusion over flavours in packets of sweets or crisps, a love of hot pink despite peer pressure and not being able to tell where they have already painted on a sheet of coloured paper.

How does being colour blind affect my child?

My answer to this is 'not as much as you'd think'.

Don't panic. Sometimes websites will really scare you and use words like 'disability', but in reality it's barely made any difference to the lives of anyone I've ever known. You may have to scratch plans to become a fighter pilot, but nowadays you can usually even be an electrician if you want.

You will find that your child has some issues at school, and it is necessary to talk to the staff so that they don't think your child is being awkward or daft. As far as I'm concerned purple reindeer pulling an orange sleigh with Santa dressed all in green are totally cool, but teachers might not see it that way if they don't know and understand.

It's really important not to crush children, or indeed anyone, when they're trying to do the right thing. If you send your child for a pair of matching socks or your red purse and get something completely different then you really have to say thank you, shrug your shoulders and try again.

Clothing choices can be a bit interesting!

Good lighting can make a world of difference. In the same way we can't tell what colour our wheelie bins are under an amber streetlight, colour blind people may have to look especially hard to tell different shades in poor light.

Things may look gorgeous to you, but rubbish to someone who's colour blind, so bear that in mind if they aren't as impressed with dinner or clothing or illustrations in a book as you are.

Traffic lights might be learnt by order, not so much by colour, and lights on elecrical goods may mean nothing if the red and green are a hue that are not easily distinguished. We had an issue with a Playstation game which had shades of green and red to say how healthy the player was. It was a really popular game, but my 16 year old was at a massive disadvantage because he had no way of telling if his character was about to die.
 
There are claims that colour blindness can hold children back at school, this has been the opposite of my experience with my 2 colour blind sons far more academic than my 2 with regular vision, and both learning to read perfectly well at the appropriate time.

A colour blind person will have frustrations at times - labelling , keeping things in the right place and other visual hints aside from colours are all helpful. You might be able to instantly see which bin is green paper recycling or which coffee is decaf, they might have to lift the lid, read the label or put a sticker on the top with a big D.

On the whole the world is aware of colour vision deficiency, and changing shades and colours so that things are accessible to everyone is usually done before you even see it. If you find a website, game, book or anything that causes confusion then feel free to contact the company or owner, and usually they will take you seriously.

I've never viewed colour blindness as any form of disability or problem, it's just a difference. We all see colour differently to others anyway. It's as natural and not much more of an annoyance as left-handedness.

I tell my children we're all different and we all have strengths and weaknesses.We should all try and appreciate those differences and try to make life easier for everyone, and in return hopefully they'll think of us too.


You can download a free app. or complete an online activity to test your colour vision which is very user-friendly and even accessible for children here - EnChroma. Please DO NOT just accept the results of any home test as a definite - as previously stated small children will become bored, or they will often answer in a way they think will please you. If you feel your child is colour blind then an Optician is the best person to confirm it, and they usually will not entertain testing until the child is school age.

It's been several years since I first wrote this post, and my boys are all older now! We recently worked with EnChroma, and the boys tested out their colour-enhancing glasses. You can see their reactions and a find out more about the glasses in our EnChroma Glasses Review - with video... 

Thank you to Colour-blindness.com for the use of the free colour change software to create the photos.

I'm not in any way medically trained, I'm just a Mum with experience of colour blindness. If you think I have anything wrong or you have anything to add then please add a comment!