I am red-green colour-blind. I am a ‘deutan’ meaning I have deuteranomaly, the commonest form of the disorder, which affects about 8% of men of Northern European ancestry. Apparently this is because my green-sensitive retinal cones don’t work properly. It is all my mother’s fault – or even my grandmother’s fault. Like haemophilia, scourge of the Romanovs, colourblindness is an X-linked genetic disorder; meaning women are usually asymptomatic carriers, protected by their paired normal Xs, while men, with only a pathetic Y to pair up with their single X, have no such protection. There is some evidence that carrier women, expressing both the normal and abnormal Xs, have enhanced colour vision, known as tetrachromacy. Apparently they can see two different kinds of red. Trichromacy is normal colour vision.
If a woman carrying the gene has a child with a normal man, there is a 50% chance her sons will be colour-blind and a 50% chance any daughters will be carriers. My grandmother passed the abnormal X (X’) to my mother and also her son, my uncle, who was colour-blind. My mother passed her X’ on to two of her three sons; a run of bad luck in the family – but not as bad as haemophilia.
In the reverse situation, where the father is a sufferer (X’Y) and has children with a normal (XX) woman, all his daughters will be carriers, but his sons, to whom he gives his benign Y, will be normal. However, if a colour-blind man (X’Y) has a child with a carrier woman (X’X) there is a 50% chance their daughters will have two abnormal X chromosomes. This is the main reason 0.5% of women have the disorder, and it is usually in a profound form.
My parents (I say parents but I was raised by my mother, my father was always too busy to bother with us) twigged that something was amiss fairly early on. I seemed to be incapable of learning my colours properly. The school was onto it too and I was sent off to Ayr to be tested. I did the Ishihara tests like the one above – and I was all over the shop. I saw numbers that weren’t there and I couldn’t see the numbers that were there. By contrast, they told me I had done surprisingly well on the tests that required you to arrange little discs of colour in order as they went from one shade to another. They couldn’t explain this. They then gave me a list of occupations I was now debarred from; things like a commercial or military pilot, a pathologist or an officer above sergeant in the signals corps. I immediately developed a yearning to be any or all of those people. Doors had been closed to me at a very early age.
I am able to see some frequencies of red, so I do not live in an entirely drab world. Other shades of red just look dark green to me and spectacular rhododendrons with dark red flowers can look all-green. I sometimes have to look for the flowers as separate structures from the leaves. Problems also arise with colours that are mixtures of other colours, so that some purples look blue to me and browns look the same as green. The reds had dropped out of the mix.
In art classes at school I was careful to ask my nearest classmate to tell me which was the brown crayon and which the green. I carefully placed them on opposite sides of the desk so that my trees would look correct. We were once asked to do a design for wallpaper. I decided to go for a Chinese theme. The teacher came round the class looking at our efforts. When she came to me she said, ‘That’s very nice Allan, bit why have you plumped for such conventional colours? Why not have blue trees with yellow leaves?’
At secondary school my favourite teacher, Mr Harrison who taught biology, had monochrome vision. His abnormal X’ must have carried an extreme form of the condition. I remember him asking us why certain colours didn’t go together. He was unable to understand the concept.
Whenever the subject of my colourblindness cropped up, people always started pointing to various nearby objects and asking me what colour they looked to me. This became very tedious. I couldn’t think of a witty response that would get me out of answering them. From birth, I have had patches of white hair among the brown on the left side at the back of my head. This too became a subject for enquiry, so I started saying that my mother had been frightened by an Ayrshire cow when she was pregnant. Similarly, when challenged for smoking cigarettes as a medic I would look shocked and say, ‘They’re not bad for you, are they?’
There did not seem to be any advantages to my condition. Since I had some concept of normal vision, when shown shades of green or pink, I knew what they should look like and could switch my perception of them back and forth from green to pink depending on what people told me I was looking at. It’s not much of a trick – and one that is entirely in the eye of the beholder. These problems did not stop me painting but the results tended to look a bit odd to normal-sighted types.
I played cricket at school, a red ball on a green pitch, but I seemed to manage OK. Years later I read a paper about this. They looked at whether red-green colour blindness was a handicap to cricketers and found that there was a slight but definite preponderance of red-green colour-blindness among first class batsmen compared to the general population. Ian Botham, for example, is red-green colour-blind. It seems a fast-moving object is perceived in monochrome because the colour-sensitive cones in your retina don’t react quickly enough. It’s those monochrome rapid rods that see the ball coming. So why would a colour-blind person see the ball a bit better than a normal? Is it because they generally rely less on colour? There is also evidence that colour-blindness helps you identify camouflaged objects, perhaps because you depend more on pattern recognition than colour.
Even if I couldn’t fly a plane, I was allowed to drive. In some countries I wouldn’t be. Here there was a potential problem. Traffic lights and brake lights are quite important. It’s easy to learn that the red light is always at the top of traffic lights – and anyway it looks completely different to me from the whitish green light at the bottom. However, I don’t see much difference between red and amber. Similarly, with brake lights, they look the same shade as side lights and indicators to me. I have to specifically look for red stop lights and brake lights as they don’t really stand out to me among all the other street lights – especially on dark rainy nights.
I can hardly claim to be handicapped. Indeed, if colour-blindness was a significant detriment to sufferers we would eventually die out. Instead, it persists. Sickle cell trait confers protection against malaria, so perhaps colour-blind hunters were better at identifying hidden quarry. I do inhabit a drabber world than the rest of you, but I cannot do anything about that.
The special glasses that claim to restore your colour vision are negatively reviewed online and I haven’t bothered trying them. Wikipedia has a list of my illustrious fellow-sufferers:
https://en.wikipedia.org/wiki/List_of_people_with_color_blindness
The Bohemian Waxwing 