Colour vision deficiency, also known as colour blindness, is not uncommon. Statistically it affects approximately 8 per cent of men and 0.5 per cent of women globally – that could be over 250 million people worldwide. It doesn’t mean that they see the world as black and white, though.1
As I’ve written before, human colour vision relies on three types of colour-sensitive cells in the eye, called cones. This is why humans, as well as many other mammals, are called trichromats. If one or more types of these three cones are faulty in some way, a person cannot perceive the whole range of colours the way a normal trichromat does.
Roughly 80 per cent of colour vision deficiencies are in the category of anomalous trichromacy, which means that all three of their colour-sensing cones are working, but one of them is out of alignment in relation to the others; usually the red and green ones are overlapping by a great deal. The effects of that can range from a very strong defect to only a mild deficiency.
For a smaller amount of people one of the three cone types actually doesn’t work at all, so there is simply nothing in the eye that can register either red, green, or blue. This condition is known as dichromacy, and amounts to roughly 20 per cent of the colour blind population.
Thus, depending on the particular deficiency, as well as its extent, a colour blind person has trouble distinguishing between certain hues – most typically these are red and green, as well as any colours in which red and green are components, such as purple. Meanwhile they can see blue and yellow just fine – unless it is the blue cone that is affected.
If you have regular colour vision, you can see more examples of various colour-perception deficiencies over at the Colour Blindness Awareness website, as well as learn more about each type.
Bringing back the colour with science
For centuries we have thought of colour blindness as a genetic condition that one simply has. There is no cure – because the difference is effectively built into their visual perception apparatus, we cannot change the way colour-blind people experience the world.
It was an accidental discovery. When surgeons working with lasers found out that their fancy light-filtering protective glasses made all the colours look really bright, they started wearing them outdoors, as sunglasses. Materials scientist Don McPherson, who was involved in the development of this special eyewear, was doing so as well. Then one day his friend borrowed the sunglasses for a moment, and for the first time in his life, saw the orange colour of traffic cones on a nearby street. He was, of course, colour blind.
This startling realisation led to McPherson joining forces with two colleagues, and they received a grant from the American National Institutes of Health for developing “an optical method for correcting color blindness.” Nearly ten years later, under the wing of their new company EnChroma, the revolutionary glasses had been designed and even gone through some clinical trials, as well as in-house product testing.
The scientific development process was extensive, although it built upon the technology of the surgeon ‘sunglasses’ mentioned:
“The key discovery was that by filtering the wavelengths of light, the color signal sent to the brain could be amplified. However, the kind of filtering needed could not be done using standard methods such as dye tinting. To amplify color, the filter must make very precise “cuts” in the spectrum—switching quickly to block individual wavelengths of light. The fast switching action is analogous to how a digital electrical signal changes between the binary states of zero and one. That is why the coating is called Digital Color Boost™.
Digital Color Boost™ coatings are made from up to 100 layers of dielectric material. Each individual layer is only a few nanometers thick—so thin it’s invisible. However, when many layers are combined in just the right way, they interact to make something more. Due to quantum interactions at the boundaries between layers, photons passing through the coating are selectively blocked depending on their wavelength.”2
To read the entire explanation of the science involved, you should head over to the EnChroma website. It’s quite fascinating, and I simply don’t have the space here to go through all the detail.
These glasses are not a colour blindness cure, and they do not work for dichromacy. They are not cheap, either. And because of the nature of the nanolayer coating, the glasses only work in normal daylight conditions outside, and are sold as an improvement for one’s quality of life, not as a device that allows people to pass colour vision tests that may be required for some occupations.
However, all that aside, there is one last thing I want to add – a video.
Turns out that over the past two years, since the glasses have been on sale, EnChroma has been encouraging customers to shoot a “first impressions” video. There are a handful of these on YouTube now, but this one is probably my favourite. It will only take you three minutes. Press play.