Oct 29 2018

Study Questions Glasses for Colorblindness

I am what is known as a mild protan. That means that the cones of my retina that perceive red and green wavelengths are not as separated in their frequency response as they should be. This overlap causes some shades of red and green to look similar. As far as I am aware, the only deficit this has caused in my life is the inability to see some of those numbers in the circles of colored dots used to test color vision. Although some color combinations, such as the orange and green of the Miami Dolphins jerseys, are uncomfortable to look at.

But other people have more severe forms of color blindness that can actually affect their lives, such as the ability to distinguish red and green traffic lights.

I was therefore intrigued on a personal as well as scientific level when I first heard the claims for glasses that can compensate for some forms of color blindness. To me the claims sounded only semiplausible. The problem with partial color-blindness is in the cones – the retinal cells that perceive color – so how could you correct this by simply filtering the frequency of light? But I left open the possibility that by specifically altering some colors you could enhance their separation, making them easier to distinguish.

I never had the opportunity to test the glasses (they are expensive) but fortunately there is now an independent study of their effectiveness. Specifically researchers at the University of Granada tested the EnChroma® glasses.  As the researchers note, the company that makes the EnChroma glasses has been watering down their claims in the typical way that supplement manufacturers often do, which for me is a huge red flag. They now state on their website:

“EnChroma glasses are an optical assistive device for enhancement of color discrimination in persons with color blindness; they are not a cure for color blindness. Results vary depending on the type and extent of color vision deficiency per individual.”

Sounds an awful lot like the “structure function” claims of supplements, which cannot claim to treat or cure any disease. I could not find more specific claims made by the manufacturer on their website. They also say things like:

“EnChroma color blindness glasses can have a profound impact on how people see their world.”

Yeah – so do sunglasses. This is a clever implied claim here, without actually making a specific claim. They also present reviews on their site, quoting other people who make more profound claims. This is the common “testimonials” approach – let other people make the claims so you don’t have to.

How do the glasses work?

To compensate for the overlap, the EnChroma lens contains proprietary optical materials that selectively remove particular wavelengths of light exactly where the overlap is occurring.

Again, only semi-plausible. The glasses filter out certain frequencies (colors) of light, which will certainly change how things appear, but it is unclear how this will increase color perception. So let’s go onto the test.

This UGR research has counted with the participation of 48 people with color blindness, after a public call to which more than 200 volunteers responded. The researchers have used, for the first time, two complementary strategies in order to evaluate the effectiveness of the glasses. The first strategy consisted in evaluating the color vision of the participants with and without glasses using different types of tests: the Ishihara test (recognition) and the Fansworth?Munsell test (arrangement). Besides, they have added a test based on the X?Rite Color Chart, which evaluates subjective color?naming.

The second approach for evaluating the effectiveness of these glasses consisted in using the spectral transmittance of their lenses to simulate different observers, which allowed to evaluate the changes in color appearance.

They found no improvement in color vision with the EnChroma glasses. Only one participant subjectively perceived colors as being enhanced. What the glasses did was change color perception, but not really improve it. So some shades were more easy to distinguish, but others were then more difficult. The authors also conclude that the glasses are similar to ones used for specific activities, such as hunting. In these cases the glasses help distinguish colors in the particular setting – such as separating animals from the foliage. But there is no overall improvement in color vision.

The study suggests that the EnChroma glasses do not represent any true advance. They are simply doing what other specialty glasses do, filter out certain wavelengths of light to alter the appearance of some colors. This will help separate some colors at the expense of others, but not enhance overall color vision.

What would be most useful is to develop such glasses for specific types of color blindness and for specific situations – for example, glasses for protans (a type of red-green separation problem) to use while driving.

What these glasses do not appear to do is allow people with color blindness to see more colors, or to approximate normal color vision. This does not address or correct the actual underlying cause of color blindness.

In the end, the marketing of the glasses is very similar to supplements – semi-plausible claims that sound impressive to the general public because they are presented in the context of underlying basic science, but without the kind of testing necessary to back specific claims for effectiveness. The claims are specifically worded so as not to make actual specific claims, only to imply them, and then coupled with selected testimonials that close the loop on the implied claims.

The bigger issue is that companies are allowed to make these pseudoclaims without needing to prove them with adequate scientific study. When independent studies come along, they have a minimal effect on the market. By then the company has already created a demand for their product with the unsupported claims.

The only real fix would be to change the regulations so that companies cannot make any health claims for any product without first providing adequate scientific evidence. Companies have somehow managed to convince a large portion of the public, however, that the consumer’s interests are best served by allowing companies free range to make unsupported health claims.

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