Synopsis: Color blindness (or color vision deficiency) affects up to eight percent of men. Until recently, doctors could do nothing to treat it. Now high-tech glasses can make colors come alive for many people with the most common form of color blindness.

Experts explain color blindness and the glasses that can treat it. Host: Reed Pence. Guests: Sean Reynolds, color blind patient; Dr. Michael Marmor Professor of Ophthalmology, Stanford University School of Medicine and Byers Eye Institute; Dr. Don McPherson, Vice President of Products, Enchroma, Inc.

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Color Blindness

Reed Pence: Sean Reynolds is a 36-year old IT professional from the San Francisco area. He’s lived all his life suffering from what most people call “color blindness.”

Sean Reynolds: I can see colors. It’s not as though the world is black and white, but certain areas of the spectrum, it’s difficult for me to tell the difference between colors. So, for example, certain shades of red and green for me are what are most difficult for me to tell apart. So, my eyes are weak in the green part of the spectrum, and the red and green overlap, so I have difficulty telling things like status lights on electronics. If it’s an LED that uses red and green, a lot of times those reds and greens are very close to one another right in that area, that I have trouble telling.

Michael Marmor: It’s not colorblindness. The colorblind man sees the yellow end of the spectrum, and he sees the blue end of the spectrum, and so he does see colors, but he can’t see a full spectrum. And colors tend not to be as important of a part of his life as it is for the rest of us.

Reed Pence: That’s Dr. Michael Marmor, Professor of Ophthalmology at the Stanford University School of Medicine and the Byers Eye Institute there. He says that the most common type of color blindness by far, the type Reynolds has, is called “red-green color blindness.” But he and many other eye professionals prefer to call it “color vision deficiency” because only some colors are invisible.

Michael Marmor: Everything from green down to red is seen the same way. So, as a result, red and yellow appear the same and yellow and orange appear the same. But green actually lies right between the yellow end of the spectrum and the blue end of the spectrum. Green is a faded grayish color to the colorblind man because he’s really not seeing any distinct color.

Reed Pence: But in spite of that markedly different way of seeing the world, color blindness wasn’t even known to exist until about 200 years ago.

Michael Marmor: The first paper that actually described this condition as a congenital problem was written by the famous, famous chemist John Dalton in 1794. You can see he was colorblind, and he recognized by what friends were telling him that he wasn’t seeing what they were, and that his brother had the same problem, and that a bunch of other men had it. Prior to that time, the colorblind individual had a real problem. He would look at a picture or look at something and describe it, and others would say “Aaaagh your judgment is terrible,” and he couldn’t understand why. And there were some painters trying to paint who were probably colorblind ( of course we didn’t have exams prior to that time) who were known as terrible with colors, who sometimes had to hire other artists to do their work. And they could never really understand why they couldn’t do it right.

Reed Pence: Today we know that color blindness is an inherited condition. Marmor says about eight percent of men have it to some degree, but only about one and a half percent are unable to tell red from yellow from green at all. Only about one half of one percent of women are afflicted. The problem results from a genetic alteration of the structure of the eye.

Michael Marmor: Our normal daylight vision comes through photo receptor cells that change light to a neural signal that are called cones, and we have three types of cones. Normally we have cones that are predominantly blue sensitive, predominantly green sensitive, or predominantly red sensitive. But the genetics for the green and red sensitive cones is carried on the X chromosome and it’s not uncommon out there in the population at large to have a faulty gene for even the green sensitive cones or the red sensitive cones and that’s the problem. If a man gets a faulty X chromosome from his mother and doesn’t have red sensitive cones, all he has are the green sensitive cones. He doesn’t see red well, and he can’t distinguish any colors between red and green.

Sean Reynolds: Someone will say “Oh, look at that green such and such over there,” and I won’t know what they’re referring to. I’ll need some other description of it. If someone says “Take that green door on the left,” I’ll need– is there a sign on it? Is there some other way for me to know which door to take?

Reed Pence: Reynolds says traffic lights don’t give him a problem, though studies show color blind people are slightly slower to react to them. Apparently the medical field isn’t too concerned about color blindness. Marmor says tests for it are not part of a standard eye exam.

Michael Marmor: Nobody ever died of color deficiency. Well, perhaps if they run a red light, but the disease is not serious. An ophthalmologist might do it on children just to find out, or to advise Mom, but it’s one of those things that, unless its quite severe in the discrimination problem, if a youngster’s beginning to have trouble, like being teased because they’re wearing a green sock and a red sock. It’s not a medical problem with any consequence, and it’s not something you can do anything about, so by and large it’s a test that’s done when somebody notices a problem and asks, “hey, is this real?”

Reed Pence: So it’s not uncommon for some men to make it to adulthood not knowing they’re color blind. Marmor says often it’s a new wife who will notice mismatched socks and bring her colorblind husband in for a test. But now if that test comes up positive, there is something that can be done for many people with color blindness. They look like sunglasses, and were invented as laser-protective eyewear.

Don McPherson: Back in the early 2000’s I was melting and manufacturing a lot of glass lenses for laser safety eyewear, which I was providing to laser companies down in Silicon Valley. And I found out through these companies that they’re having a problem with the laser surgeons who were “borrowing,” shall we say, the eyewear and taking them home with them, and they were using them as sunglasses.

Reed Pence: That’s Dr. Don McPherson, Vice President of Products for Enchroma, incorporated, in Berkeley, California, and inventor of Enchroma CX lenses. He says he started wearing a pair as sunglasses, too, to see what the attraction was. Eventually, he wore them to an Ultimate Frisbee tournament.

Don McPherson: And a friend of mine borrowed my sunglasses, and it turned out he was colorblind, and he said that for the first time he could differentiate the fluorescent orange field marking cones from the bright green grass, and that was a bit of a shock to me. But like I said, I found out he was colorblind, and as a scientist I got curious about that and started to research it. That led to three grants from the National Institute of Health to do clinical trials to try to understand what was going on and try to develop eyewear that would be beneficial for color deficiency.

Reed Pence: McPherson says the glasses work for about 80 percent of people who have red-green color blindness. Those who have a type called anomalous trichromacy.

Don McPherson: And what differentiates it from more sever forms of color deficiency is in those more severe forms, you might only have one or two functional photo pigments in your eye instead of the normal three, but in anomalous trichromacy–the kind that we can correct with Enchroma glasses–all three photo pigments are present. It’s just that one of those three photo pigments, in this case one of the green or red sensitive ones, is shifted spectrally so that it overlaps its neighboring photo pigment too much. And what happens then, you’ll look at something that has a color to it, say a red apple, and instead of getting a distinct signal to each of your photo pigments, you get a signal to your green and red photo pigments which are too similar. So, when the brain tries to understand what that color it is, it comes up with brown, and when it looks at the leaves on the apple tree it also gets brown and that’s where the color confusion comes in.

Reed Pence: McPherson says the glasses work by filtering out the overlap of colors.

Don McPherson: Just imagine that you have a rainbow, and the place where this overlap occurs is occurring in the yellow portion of the spectrum. And what the glasses do, is they remove that section of wavelength of light –the yellow wavelength–which are the cause of the confusion, and in essence you can just visually imagine they’re pushing the two photo pigments back apart so they don’t overlap as much. And in so doing you reestablish something like normal color perception.

Reed Pence: But it’s not as if someone who’s been color blind their whole life can just slap on a pair of sunglasses. McPherson says the brain can be confused by what the eyes are now seeing, so it takes some time to adapt.

Don McPherson: Since they’re getting new information to their brain, new quantitative data, they have to understand it, and sometimes that takes just a matter of a minute, and for some people it takes days before they can understand what they’re seeing. So, when they do start to recognize colors that they haven’t seen before, it’s pretty overwhelming emotionally for them.

Reed Pence: Sean Reynolds signed up to test Enchroma’s glasses, and while his first wearing wasn’t emotional, it was certainly striking.

Sean Reynolds: I got in my car and started driving away from their office, and immediately there were things–like there was a tree in front of a brick wall, and all of a sudden the difference between the red brick and the green tree just absolutely leaped out at me. It was surprising to me how different those colors were when before I could tell the difference but they weren’t so distinct. You know, I turned the corner and there were some California poppies in a person’s yard, and the orange of them was super vibrant, and it really jumped out at me. I just thought, “Wow, those are some really colorful flowers!” And then the biggest surprise was I turned the next corner, and I came to a traffic light– it was red when I got there, and when it turned green, that green light was really, really green. I didn’t expect that at all.

Reed Pence: McPherson says he hears that a lot. Colorblind men report they can more confidently shop for clothes or for fruits and vegetables. They’re also more confident driving. And for some children, seeing in color makes a difference in school.

Don McPherson: Something around three quarters of all information is visual, and a large majority of that, as you know, is color coded. So, and they find that people perform better in a learning environment if they can detect all the colors. And we’re getting reports back from the parents of the kids that their children are performing better in school.

Reed Pence: And while relatively few professions require accurate color vision, among them pilots and police and fire personnel in some jurisdictions, there are some jobs where it certainly helps. Painters, for example. And, Reynolds says, IT. And while a lot of people downplay the impact of color blindness, Reynolds says they probably have never experienced it. Color blindness usually isn’t life threatening, but it does detract from a person’s quality of life. With his new glasses, now Reynolds says he looks forward to going outside just to see what he’s always missed. Now he can stop and see the roses. You can find out more about CX lenses for color blindness at You can find out more about all of our guests on our website Radio Health Journal dot net. I’m Reed Pence.

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