The Colours Some Eyes Miss

The story

At the back of your eye lives a carpet of tiny light catchers. Some of them, called cones, are the ones that catch colour, and they come in three kinds. One kind answers most strongly to reddish light, one to greenish light, one to bluish light. Every colour you have ever seen, every sunset and crayon and butterfly wing, was built by your brain from just those three reports.

Now imagine one of the three kinds is missing, or answers a little differently than usual. The brain still builds colours, but some of them land closer together. For the most common kind of colour blindness, reds and greens stop looking like strangers and start dressing alike. A red pencil and a green pencil may look like near twins. Traffic lights are learned by their position in the row, rather than by colour alone.

This is usually passed down in families, written in the recipe a child is born with, and it visits boys far more often than girls. It is also much more common than many people think. In a classroom of thirty, there is a fair chance somebody sees colour this way, and has quietly learned to work around a world that keeps colour-coding everything.

The first scientist to study it carefully was studying himself. More than two hundred years ago, an English scientist named John Dalton realised that flowers other people called pink or red looked quite different to him, and he wrote the first careful description of the condition. He even asked that his eyes be examined after his death, so the puzzle could be studied properly. Scientists honoured that wish, and much later, using his preserved eyes, they confirmed exactly which colour catcher he had been missing. For a long time, colour blindness was simply called Daltonism.

And what about those famous glasses, the ones in videos where someone puts them on and cries at a sunset? Here is the honest truth. The glasses cannot give an eye a colour catcher it does not have. What they do is filter the light, trimming away the confusing overlap, so that for SOME people reds and greens pull further apart and look richer and easier to tell apart. For others they help only a little, or not at all. They are a clever helper, not a cure, and the tears in those videos are real even when the science is smaller than the video makes it look.

The kindest thing to know is simple. Colour-blind eyes are not broken eyes. They see a full and detailed world, just with a different palette. So when you make a chart, a game or a map, use shapes and words as well as colours. Somebody near you will quietly thank you for it.