Once upon a very long time ago in a far distant land a thirteen year old boy was walking along a tropical beach skirted by thick jungle, with his parents. He was a right skinny-ma-linky-long-legs, but that's not all that was wrong with him as he was about to find out. His father said "We'll walk as far as that red sign and turn back." The boy said, "What red sign?" His father tried to point out where the red sign was, "There, up against the trees." but his efforts were in vane. However I do recall that the boy gave him a nod indicating that now that he'd pointed it out he could see it. They pressed on, and when they were but 50 yards (they were in a part of the world that was coloured red in atlases, i.e. the British Empire, so they didn't do metres) from the sign the boy could finally distinguish it from its backing of green jungle. He just about stopped himself from blurting out then "Oh, that red sign" which would betrayed his condition of achromatic vision.
So I kinda knew from that moment on that I was colour blind within the red/green spectrum of light.
Subsequently I have failed every Ishihara test I've taken. I keep trying to tell the tester I can see a number in the coloured spots. Ok, it might not be the same number that the tester is seeing but does that really matter? This pathetic attempt of persistent denial is always dismissed with a sympathetic smile and a kind farewell remark like "Take care, and remember the green light is the one on the bottom."
