Saturday, 15 February 2014

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 Father-In-Law-To-Be. 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
Deuteranomaly colour blind colourblind
Mild Green Colour Blindess - Deuteranomaly
colorblind Colourblindness Colour Blind red/green
Green Colour Blindness - Deuteranopia
Colour blind vision red green protanomaly
Mild Red Colour Blindness - Protanomaly
red green colour vision deficiency colourblindness
Red Colour Blindness - Protanopia
Colour deficient colorblind triatanopia can't see blue
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.


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


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!

28 comments:

  1. That's very interesting to see the pictures and the difference it makes, I was worried that with all my sons sight problems that colour blindness would be the next one. I have had him tested and all good, but I still think he cant see pink and yellow!

    ReplyDelete
    Replies
    1. Maybe he's just selective. I'm not a fan of yellow, so if I had a choice it's definitely one I'd miss out ;)

      Delete
  2. It's really interesting. My dad really struggles to tell the difference between flourescent colours but I'm not really sure how that fits into the blue-green-red blindness. I have been known to think too much about the philosophy behind colour (how do we know that what everyone says is green etc etc) I think it can all be very subjective really!

    ReplyDelete
    Replies
    1. Thanks Pippa :)
      I know mine can't tell yellow and green flourescent apart, and it would make sense they couldn't separate orange and pink either. I agree with you on the philosophy. I smell things differently to everyone else and I only know that because as a small child I had a proper sense of smell, I'm totally willing to assume we all see differently :)

      Delete
  3. That's really interesting to see the pictures, the mild ones don't seem to make too much difference at all but the others are so different! I suppose for colour blind people, that's their everyday vision so that is their own version of normal

    ReplyDelete
    Replies
    1. What do you mean, not very different?


      Nah, I'm kidding....they aren't really :D I love computers because a few years ago it would have been virtually impossible to show, and now it's really easy.

      Delete
  4. That was a really interested read and great for anyone with initial concerns about colour blindness, something I've not come across before.

    ReplyDelete
    Replies
    1. Thank you Fiona, that's a lovely comment - glad you found it interesting :)

      Delete
  5. Some useful information there and the colour examples are good as we have a friend who is red colour blind, but I have never really understood what that meant

    ReplyDelete
    Replies
    1. Thanks Angela - I'm glad you found it interesting :)

      Delete
  6. Great post Jenny. I never knew there were different types of colour blindness and always wondered how people see things when they are colour blind.

    ReplyDelete
    Replies
    1. Thank you Laura - lovely comments! Glad you liked it :)

      Delete
  7. Fantastic post! The pictures you have are really interesting - I have never even really thought about being colour blind or the fact there were different types. I'm sure this post will help a lot of people.

    ReplyDelete
    Replies
    1. Thank you! That's a lovely comment! I'm really glad you found it so interesting :)

      Delete
  8. The picture do help a lot for someone like me who is very visual. I like to see what I learn! Really interesting post.

    ReplyDelete
    Replies
    1. Thanks Kel - I felt the post really wouldn't work without the pictures :)

      Delete
  9. Is this the bit where you knock me over and say my dad was colour blind ???

    ReplyDelete
    Replies
    1. I do not know. Your Grandfather was, but that has no bearing on his sons. Your Grandma would have to be a carrier to pass it down the male line. I'll ask for you and see if I can find anything :D

      Delete
  10. Fascinating post Jenny and one I'm really interested in. I won't be surprised at all if Monkey turns out to be colour blind - he seems to struggle constantly with red and green but no other colours at all, and has done forever. I'll have to ask OH about his family history, there is none on my side of the family.

    ReplyDelete
    Replies
    1. It would come from you - not your other half. Dads have no bearing on whether a boy is colour blind :D
      I find they are confused by purple, and salmon pink and lilac colours are impossible for them to tell - hope that helps :)

      Delete
  11. I find this really interesting my husband is colour blind not sure what type. My stepdad is also colourblind but different to my husband

    ReplyDelete
    Replies
    1. If you use the link towards the bottom of the page then it has an activity that will tell your husband which type of colour blindness he has - if he wants to know. I found my family weren't really bothered - I was more interested than them because I can see the difference :)

      Delete
  12. I've never come across anyone with colour blindness before (actually I probably have and just don't know it, I guess) so I found this really interesting, especially the different picture effects to show the different types. What a helpful post - thank you!

    ReplyDelete
    Replies
    1. Thank you for your lovely comments - I'm glad you enjoyed it :)

      Delete
  13. I found this very interesting, good to be made aware of how you might spot the signs. Thanks

    ReplyDelete
    Replies
    1. You're welcome. It seems so weird to me that people haven't really come across it because half my family have always been colour blind :)

      Delete
  14. My son (8) has failed on the colour blindness test the doctors too but I'm not really sure if he is colour blind.

    ReplyDelete
    Replies
    1. It may be that he's only mildly colour-blind, in which case it will only very rarely make any difference. You can try him with the colour-blindness test I linked to up there, it's the best I've seen, very quick and very easy :)

      Delete

Thank you for taking the time to leave a comment. I read every one and try my best to reply!