When can they detect colour blindness?

[Mum2Ela]

Colour blindness runs in my family. My younger brother (now 18) is colour blind and the school were never told.

Surely it must be hinderance?

DS is now 18 months and I am just wondering when it can be detected ad whether, when he goes to school, to inform them. Or am I being silly and over-reacting?

I wondered about this too, when ds was about 2yo, as he could name many colours, but couldn't differentiate between red and green. My HV said that a lot of aspects of vision and, particularly, understanding what you see, develop at different rates, and that his red/green confusion wasn't significant at that age. If he still couldn't tell the difference by school age, then it might be worth testing. In the meantime she sugggested that, rather than talking about colour names, we played colour-matching games. Oddly enough, although he knew the names of many colours, ds couldn't do colour-matching for a long time. Then, suddenly, he could do it, and although he still got the names confused, it was obvious that he could differentiate between red and green. I don't remember when this was, but probably before age 3.

The optician can do it from when they can recognize animals or numbers or cars etc

They have pictures with lots of circles

and different coloured picture inside the picture

and if colour blind will not see it or see it differently

iyswim

\link{http://www.toledo-bend.com/colorblind/Ishihara.html\here you go these are the tests they use}

HV advise to take children to optician for a eyesight test just before they start school. They will do a colour blindness test then. DS1 is colour blind. Hasnt really hindered him but I do always let the teacher know. Sometimes if they are working with reds on blacks etc he cant see anything is there! Not so much of a problem now they tend to work on white boards rather than black boards.

Mum2Ela, from what I know, your DS has only a 25% chance of being colour-blind. (You have a 50% chance of being a carrier, depending on which X-linked gene you got from your mum. Your DS has a 50% chance of gettint the colour-blind gene from you.)

Both my boys have 50% chance (each) of being colour-blind. Must remember to try testing DS1 again (he's 4.5, and just getting good with numbers etc). I have told his school that it's possible he's colour-blind.

NotQuiteCockney has my DS got a 25% chance or a 50% chance of being colour-blind? I don't understand.

25% chance.

You have a 50% chance of being a carrier. If you have the gene, your son has a 50% chance of having got it. 50% x 50% = 25%. Sorry, previous post wasn't clear enough.

(I know I am a carrier, because my father is colour-blind, so the X I got from him has to have the colour-blindness gene on it, as he only has one X gene to give me. Hence my sons have a 50% chance, each.)

aaah, I seeeeeeee. That makes sense.

x