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Biological Chemistry

Experimenting with EnChroma’s color-blind assistance glasses

by Craig Bettenhausen
February 6, 2017 | APPEARED IN VOLUME 95, ISSUE 6


Correcting chemistry’s colors

Driving while color-blind is dangerous: Green stoplights look white and are often hard to distinguish from streetlights. So you guess or get help. A company called EnChroma now makes lenses that it claims “enhance the vibrancy and saturation of colors and help the color-blind discriminate between colors that can be hard to see.” But EnChroma is careful to say its glasses are “not a cure, a fix, or a correction for color blindness,” says Kent Streeb, director of marketing at EnChroma.

Credit: Shutterstock/Matthew Wickline/Human-Computer Interaction Resource Network
Best guess: To many color-blind people, these photos are identical. The version on the right is a simulation of deuteranomalous color vision impairment.
Credit: Shutterstock/Matthew Wickline/Human-Computer Interaction Resource Network
Best guess: To many color-blind people, these photos are identical. The version on the right is a simulation of deuteranomalous color vision impairment.

Newscripts wanted to delve into the science of the special spectacles and see how the technology might help color-blind scientists in the lab.

Human color vision is based on three types of light-sensitive cells in the eye. Called cones, the cells respond to blue, green, and red light. The brain calculates perceived color by measuring how strongly the different types of cells are stimulated by the light coming from a given object.

Lab Tour
EnChroma says its glasses can help some colorblind people distinguish colors better. C&EN took the special spectacles to the Department of Materials Science & Engineering at the University of Maryland, College Park, to see how helpful the technology could be in a working scientific laboratory.
Credit: C&EN

All three kinds of cones use the same light-absorbing small molecule, or chromophore: 11-cis-retinal. In isolation, it has an absorption peak in the ultraviolet region of the spectrum. The biochemical trick to color vision is that this chromophore is placed inside a barrel-shaped protein, explains ophthalmology professor Jay Neitz of the University of Washington, Seattle. Amino acids point in from the walls of the barrel, altering the distribution of electrons on the chromophore. The more electron density is pushed onto a ring at one end, the further the absorbance of the light is shifted toward the red region.

The three varieties of cone cells each express a different version of the protein that shifts the chromophore’s absorbance so it peaks at 420 nm for blue, 530 nm for green, and 560 nm for red. But in 8.0% of men and 0.5% of women, a mutation in the genes coding for one or more of those proteins results in a cone that absorbs in the wrong place—or not at all.

Red-green color blindness, the most common type, is a result of the absorption band of the green cones being shifted to the red, or vice versa. The closer the two peaks are, the worse the color resolution gets.

EnChroma says its glasses work by blocking select bands of wavelengths of light—in optics lingo, the glasses contain a notch filter. The idea is that the notches create greater separation between the red and green signals entering the eye, allowing the brain to better calculate the colors.

Patrick Stanley is a graduate student in materials science at the University of Maryland, College Park. Stanley has a moderate case of deuteranomaly, meaning his green cones are red shifted. Newscripts went to UMD to let him try EnChroma’s glasses; the company provided two pairs free of charge for this experiment.

“Primary colors seemed more their color,” Stanley reports of his time wearing the glasses. “Labels and boxes caught my attention more—and I guess the point of a hazardous label is to catch my attention.” He also could tell the difference between red and green LEDs and felt more adept at color-matching tasks such as tracing gas lines and reading graphs. “I found myself being quicker in making color assertions,” he says.

Neitz, the color vision researcher, is skeptical of the technology. Until the absorbance peak difference drops from 30 nm to 3 nm, he says, most people don’t notice a problem. But that’s too close to fit a meaningful notch between the peaks. So the glasses wouldn’t work for people with impairment severe enough that they consider themselves color-blind, whereas the people the glasses can help don’t need it, he argues.

Neitz’s skepticism is bolstered by a UV-visible absorption spectrum Newscripts took of the glasses. The major notch we observed was centered at 595 nm, off to the red side of the red cones’ absorbance, not between it and the green. When asked, EnChroma asserted that the 595 nm band is properly placed to adjust the light signals that reach the cones.

EnChroma agrees that the glasses won’t work for people with severe color impairment, which it says is around 20% of cases. But the firm argues that its glasses do make a difference for people with milder impairments. “I’ve positioned myself in a place where my color-blindness does not impact my daily job,” Stanley says. “But I’m definitely seeing something with these glasses.”


Credit: C&EN/University of Maryland, College Park
Ultraviolet-visible absorption spectra of EnChroma’s indoor sunglasses suggest it would block a band of light centered on 595 nm.
Sources: C&EN/University of Maryland, College Park

Craig Bettenhausen wrote this week’s column. Please send comments and suggestions to



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Donald Fairchild (March 2, 2017 9:38 PM)
Back in the early 1980's I tried a color correction lens for my red/green color blindness. It consisted of one lens with a raspberry tint to it, and the other lens was normally clear. I could see a big improvement over my colorblind eyes.
Do these "notched" filter lenses operate on the same technique? I got the impression that since both of my eyes were seeing different color scales, then my brain must have been compensating.
Is it possible to try one of these "notched" lenses?
Craig Bettenhausen (March 6, 2017 10:55 AM)
The folks at EnChroma mentioned the tinted-glass approach in my interviews with them. They said that the improvement their notch filter makes over those is that they don't distort other colors the way a conventional tinted glass would. But skeptics of the tech might dispute that, saying that both types will improve distinctions between some colors and impair distinctions between others. If I'm able to confirm either side of that debate as I wear them (I'm also colorblind), I'll try to report back here.

The EnChroma glasses in my experience do have a slight tint, the indoor ones read as blue and the outdoor ones maybe a little maroon. But the tint effect, to me, is mild.

As far as trying them, you'd have to contact the company. I don't know if they have them in certain stores or anything like that.
Will (September 14, 2017 9:13 PM)
"Driving whilst colourblind is dangerous."

How so? Reference to a study showing increased MVAs in those with colour blindness please.
David Crandon, O.D. (January 1, 2018 7:42 AM)
I have read this assumption that CVD results in greater MVA's, but I am sure that the increase is very, very low. As an Optometrist, this assertion was studied extensively by us when in school.

There are probably retrospective studies out there. But, when explained properly, you don't need the studies to understand that while in theory it presents a much greater risk (which give rise to authors saying this frequently), but in practice is very, very small.

If we talk about actually color blindness, not color vision deficiency, the danger is obvious. You won't be able to tell the difference between traffic lights or street signs.

If we talk about color deficiency, the danger is less so, because we use other visual cues to make up for it. But, as an example, for myself, I'm a protanomalous trichromat. This is a severe red color deficiency. Affects about 20% of CVD people. Essentially, any color that is pure red is hard for me to make out at all. Depending on lighting, it's grey or black or just "not there". Also, any color with red mixed in with it (remember that most colors are not pure, they are a mixture of red, green and blue) will look different to me than a person with normal color vision.

I make stop signs out because of the shape and wording, not because they are red. Orange caution signs look dull and faded to me.

But most importantly, red stop lights can become barely visible. Some stop lights are so pure in red, that they don't even look like they are on. I have to determine that the red stop light is on by noticing that the yellow caution light and the green go light are "not" on! And this even can sometimes be difficult if the sun is shining on the light and washing it out. Sometimes I have to consciously study the lights for several seconds to figure it out. I look at traffic that is moving to help as well.

These things (not just CVD) are why our traffic designers throughout the years have devised other methods of determining what traffic signs are such as shape and placement, to make it easier for motorists to figure them out.

I am absolutely sure some MVA's have been caused by CVD, because I'm an Optometrist and I remember reading them in school, but because it's obvious when you know how CVD works, I'm not gonna bother searching them out.

Hope this helps.
Paul Moeykens (November 9, 2017 1:31 PM)
I am red-green color blind and NOT a dangerous driver. As long as you realize that you're colorblind, there are a bunch of rapid compensating methods to use while driving so that you're not confused by (for instance) green traffic lights that look like streetlights.

I am also an electronics technician, and over the years have developed many compensating methods to deal with my color blindness; just the same as I have done for my driving.

I won't say that my color deficiency isn't, at times very annoying, but it is certainly manageable. The biggest problem is that I society doesn't seem to recognize that a significant percentage of men are colorblind, especially red green colorblind. Just a few minor changes in how industry creates graphs, traffic lights, or even weather maps would make a big difference. My biggest pet peeve= single LEDs that change from red to green to indicate that something is normal or, has trouble.
Leonard Kalikow (December 17, 2017 12:23 PM)
A close friend has blue-green color blindness. Will these work for him?
Craig B (December 18, 2017 12:31 PM)
I've heard of blue-yellow, but not blue-green, so I'm not sure. I'd suggest they take the test on the company's website. It'll give an assessment of what type they have and a likelyhood that the glasses will help them.

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