Colour vision deficiency

EnChroma—a company based out of Berkeley, California—is developing glass lenses with the intent of assisting individuals with colour blindness.

Not so fast, the EnChroma Cx Lenses aren’t a treatment for the condition; colour blindness cannot be cured. This technology works in a manner that is similar to how hearing aids assist those who are hard of hearing.

EnChroma is collaborating with Valspar Paints in a campaign entitled #ColorForAll. The campaign has a series of YouTube videos in which individuals describe their experience with colour blindness, including when they learned when they were colour blind.

 

Colour vision deficiency

Colour blindness, more accurately termed colour vision deficiency, comes in many forms and has many different causes. It was first recognized in the scientific community at the end of the 18th century. It is estimated that 300 million people have colour vision deficiency worldwide.

There are millions of light-detecting retinal cone cells containing molecules called photopigments at the back of the eye in a layer called the retina. These cells are divided into rods, which work most effectively in low light, and cones, which detect coloured light.

When these photopigments are activated by light targets, they send information to the brain, which enable people to see.

There are three active types of cones in the eye that are specific for different colour ranges of light. We have one type that works best for red light, one type for green light, and another for blue light. People with properly functioning colour vision are said to have trichromacy.

One of the most common forms of colour blindness, anomalous trichromacy, is usually caused by extremely high overlap in the colours that are detected by red cones and green cones. All of the cones in the eye work, but they are a bit faulty.

These conditions are usually caused by small changes in the genes that encode for the parts that detect light – molecules called opsins.

There is usually a fair amount of overlap in the colour ranges detected by the red and green cones.

In anomalous trichromacy, however, either the red cone absorbs too much green light, called protanomaly, or the green cone absorbs too much red light, called deuteranomaly.

The relation between green and red cones is determined on a genetic basis. The opsins used in red and green cones are encoded in genes and found together on the X chromosome.

The X and Y chromosomes are known as the sex chromosomes, and are responsible for the determination of sex in a developing human. XY individuals typically develop male sex characteristics, while XX individuals typically develop female sex characteristics.

Colour vision deficiency defects on the X chromosome are very common. The red and green opsin genes are often damaged or missing. These conditions are sometimes referred to as red-green colour blindness.

Red-green colour vision deficiencies are hereditary and are linked to sex. XY individuals are most likely to be affected by red-green colour vision deficiency because they only possess one X chromosome.

In XX individuals, colour vision deficiency is recessive. This means that XX individuals require two defective copies; in individuals with one faulty copy, the good one picks up the slack.

Individuals who only have two working cone types have dichromatic colour vision. If the red cones are missing, this is called protanopia and if the green cones are missing, this is called deuteranopia.

Colour vision deficiencies regarding blue cones are extremely rare. These types of colour vision deficiencies are caused by defects of the blue cone opsin gene on chromosome 7.

Colour vision deficiency caused by faulty blue cones is called tritanomaly, while the loss of blue cones is called tritanopia.

Since blue cone defects are not found on the X chromosome, they affect XY and XX individuals equally – they are not sex-linked.

Individuals with only one working set of cones cannot distinguish colour. This extremely rare condition, called monochromacy, results in the world being perceived in greyscale.

 

So how does EnChroma work?

The EnChroma lenses were developed through a project that was funded by the National Eye Institute, a division of the United State’s National Institutes of Health. The colour-boosting technology was developed after more than 10 years of research and development.

EnChroma is headed by lawyer Tony Dykes, glass scientist Don McPherson, and applied mathematician Andrew Schmeder.

The idea for the glasses stems from lenses that McPherson had developed while working on laser eye surgery protection.

The project began with the development of a computer model of human colour vision. This in silico modelling allowed the researchers to determine the colour filters required to assist different cases of colour vision deficiency.

Clinical trials were conducted at the University of California’s Davis Eye Center and Berkeley School of Optometry.

The EnChroma lenses work by emphasizing the separation between the colours of light detected by red cones and green cones. EnChroma lenses work specifically for individuals with anomalous trichromacy.

The lenses work by creating something the developers call a “spectral notch,” which causes a divide in the overlapping colours that red and green cones detect.

Unfortunately, if these colour ranges overlap completely between the two cone types, then there is no difference that can be enhanced to aid in detection.

By removing the fuzziness that occurs where the red and green cones overlap, the filter allows for easier differentiation between the two colour ranges in colour vision deficient individuals.

Based on studies of effectiveness, EnChroma has concluded that about 80 per cent of colour vision deficiency cases can be aided by their glasses. The effects experienced by users include colour perception that is brighter, with increased saturation. This allows for improved colour discrimination.

The colour-enhancement effect also works on individuals with unimpaired colour vision. EnChroma lenses are designed in a way that doesn’t alter the colour balance of the glasses – they boost all three colours simultaneously.

The lenses function as basically a colour-enhancing pair of sunglasses. The creators of EnChroma suggest optimal use whenever venturing outside.

The EnChroma glasses are intended to improve the quality of life of individuals with colour vision deficiency. They are not intended for colour vision deficient individuals to pass occupational tests which restrict them based on safety concerns.

EnChroma Cx glasses range in price, from $324.95 to $449.95 USD, on their website. The company also has a colour blindness test that you can take to see if their product will work for you.

With the development of EnChroma glasses, the future of eyesight technology is looking bright.