[george (OP)]

What causes colourblindness, and what does a colourblind individual actually "see"?

G

[another_someone]

In very crude terms, if someone shows you two cards, and you say they are both exactly the same colour, but the person showing you the cards insists that one card is green, and the other is red, but you are on the verge of calling him a liar, because you cannot tell them apart, then you are colour blind.

Whether you happen to call the colour red, or you happen to call it green, is immaterial, for both colours are the same to you.

This is only one form of colour blindness (although probably the most common form), and it is an extreme example of what often exists in a milder form, but it does demonstrate in principle what colour blindness is about.

[Carol-A]

In the retina at the back of the eye, there are two different types of light receptor... rods and cones. The rods give vision without colour, basically black, white and shades of grey. The cones can detect colour, and it is thought there are 3 types, red, green and a few blue. We get our colour vision from a mixture of these being stimulated at any given time. Colour blindness is caused by a defect in one of the types of cone (although rarely it can be a result of damage to the retina, optic nerve or brain). No one can be sure what a colour blind person sees, but it is thought to be grey.

[Gaia]

Another interesting point, more men than women are colour blind.

[Carol-A]

Thats because the genes are carried on the X chromosome.

[ChaoticBliss]

Hey guys, what's going on? I just wanted to hop into this because about two years ago my sister punched me in the eye, and after I regained consciousness and vision, the left side of my world was in black and white (greyscale). Ever since I have had a monochromatic left eye. Who knows.... Anyways my right eye, which is my dominant eye, really makes up for it and I can hardly tell when I have both eyes open and focused. Any thoughts? [|)]

ChaoticBliss

[another_someone]

Hey guys, what's going on? I just wanted to hop into this because about two years ago my sister punched me in the eye, and after I regained consciousness and vision, the left side of my world was in black and white (greyscale). Ever since I have had a monochromatic left eye. Who knows.... Anyways my right eye, which is my dominant eye, really makes up for it and I can hardly tell when I have both eyes open and focused. Any thoughts? [|)]

ChaoticBliss

Don't know, but it sounds like it could be some sort of nerve damage (either the optic nerve, or the brain).

Do you have any other symptoms (loss of vision, or reduced vision, in part of the eyes, etc.)?

Have you seen your doctor about it?

[ChaoticBliss]

Yeah, I saw a doctor, but they couldn't find anything wrong,  either with my retina or anything. I am assuming some connection is damaged, because my yellow-blue, red-green, and luminosity cones are all working just fine. They can't fix it, it's a permanent deal but it's just a fact now. I do still dream sometimes, in full color...

[paul.fr]

do colour blind people have to pay for a colour TV licence?






sorry

[Seany]

Another interesting point, more men than women are colour blind.

Hang on.. My science teacher said that females cannot get colour blindness.
So, my science teacher is a liar? waaaaaaaaaaaaaaaaaaaaa.. She said that women can only be carriers of colour blindness..

[camflht]

seanahnuk, your science teacher is incorrect.  One in 10,000 women are color deficient.  Very few people are truley color blind, that means they see no color at all.  Color deficient is the correct term, since most people only have a problem with certain colors or shades. I myself (I'm female) cannot see green if it is mixed with brown, such as olive shades.

[another_someone]

I myself (I'm female)

Not according to the profile you've put up on the site []

[camflht]

Thank you, another_someone.  I left my profile unfinished and open on my desktop while I went to see a patient.  Someone I work with changed my settings and finished it for me as a joke.  I'm lucky I did'nt get an interesting bio added. This explains the peculiar post it note left on my screen.

[Bored chemist]

There is another odd aspect of this I saw in New Scientist a while back. There are small variations in the colour receptors, which ones you get are determined by genetics and chance. Since women get 2 copies of the red/ green receptor gene they sometimes get 2 different ones. In some circumstances this enables them to distinguish colours that are the same to other people.

[paul.fr]

There is another odd aspect of this I saw in New Scientist a while back. There are small variations in the colour receptors, which ones you get are determined by genetics and chance. Since women get 2 copies of the red/ green receptor gene they sometimes get 2 different ones. In some circumstances this enables them to distinguish colours that are the same to other people.

i think i have that edition, somewher, BC.
Chris  i believe also touched on this within the last few months.

[Seany]

seanahnuk, your science teacher is incorrect.  One in 10,000 women are color deficient.  Very few people are truley color blind, that means they see no color at all.  Color deficient is the correct term, since most people only have a problem with certain colors or shades. I myself (I'm female) cannot see green if it is mixed with brown, such as olive shades.

Thanks for that. So females can NEVER be truely colourblind - see no colours. But males can?