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A Critical Thought: Colorblindness

Riley Sproul A Critical Thought, Ideas, Neurology, Science Leave a Comment

Today we’ll be looking at colorblindness/deficiency: The definition and various types, technology that already exists, and what might exist in the future. Also, this topic is a personal one to me, so there are also some ‘fun facts about the author‘ included near the end.

This topic differs from what I usually discuss in that there are no claims being researched. This installment is a critical and in-depth look at colorblindness. Enjoy!


 

 

I have red-green colorblindness, or more accurately; I am red-green color deficient. Which means that I don’t see (some) colors the same way you regularly sighted folks do. Let me explain…

 

How:

Colorblindness is an issue with the light receptors located in the retina of the eye, called cones. Not all of them however, humans have 3 types of cones, each picking up on different wavelengths (colors) of light.

F16-01 Human eye

Click for a better quality image

When a beam of light hits a cone, it sends a signal to the brain saying, “Hey Brain! I saw light of this color!” (I imagine cones to be very enthusiastic). But the cones of a colorblind/color deficient person, doesn’t quite know what they’re looking at.

Normally, when a red-sensitive cone is exposed to green light, it will sit there quietly and twittle its figurative thumbs. But when a broken red cone is put in the same situation, it can react a number of ways. Sometimes it will stand up and emphatically scream it has found red light. Other times it might loudly clear its throat and suggest there may be red light near. And sometimes it may even confuse colors the opposite way, interpreting red as green; ignoring red light when it shouldn’t. Which of these reactions takes place however, is dependent on the type of colorblindness/deficiency the cone has.

There are four types of genetic color blindness/deficiency.

1) Deuteranopia/Deuteranomaly– The most common form, where red and green colors are muted. It stems from a mutation in the green cone, resulting in either a “green weakness” or total “green loss”. Other colors effected include green/blues and blue/purples. (This is by far the best type, and that’s an opinion not at all based on the fact that it’s my own deficiency… ok maybe a little). Approximately the colors as seen by a person with Deuteranopia.

2) Protanopia/Protanomaly– A slightly rarer form, in which a confusion between red and green (and some blue/greens) coming from a red cone mutation, resulting in a weakness or loss of the color red. Some colors are lost, but the non red/green spectrum is more or less intact. Approximately the colors as seen by a person with Protanopia.

3) Tritanopia/Tritanomaly– A very rare variety known as blue-yellow colorblindness/deficiency. This is when the blue cone has the mutation, and it yields problems in a wide range of colors, excluding reds and some greens however. Approximately the colors as seen by a person with Tritanopia.

4) Total Color Loss- Just what it sounds like; all three of the cone-types of the retina are either totally disabled or absent. The individual can see no color at all, and is left with only the rods, which can simply differentiate levels of brightness.

The difference between these four are dependent on which gene is mutated. The ‘blueprints’ for the cones are within a given gene, within the X Chromosome, of each cells’ DNA.

Edited From Original

Click for a better quality image (Edited From Original)

But for each type of colorblindness, a different gene (all on the X chromosome) is effected, or mutated.

In the case of Deuteranomaly (my case), the mutated section is somewhere between the base pairs 153,448,085 to 153,462,352 (Source 1, Source 2). The keen observer may have noticed these are nearly the numbers that appear in the title image for this post. That image is of my only (current) tattoo, which is on my left shoulder. It reads the chromosomal area (Xq28), the gene (OPN1MW), and the base pair region where my Deuteranomaly mutation is located.

To review. Depending where the mutation is the X chromosome, different kinds of problems arise in the different cones of the retina; which pick up red, green, or blue light. When those cones send confusing or incorrect messages (or no messages at all), the brain gets incomplete information, and the person can’t view the full color spectrum.

 

Why:

An interesting question is, “Why do the colorblind/deficient mutations exist at all? If seeing color is important, then wouldn’t evolution have out-witted those foolish X chromosome mutations?” The answer is complicated, and in some ways still up for debate. Color vision was/is definitely important to the development of our species, and that’s why (genetically caused) total colorblindness is so rare. Even the more severe forms of color deficiency are few and far between (.0001% of people have Tritanopia). But why then is the most common type, Deuteranomaly, still at a steady 5%?

One argument is that, due to its lack of severity, it just wasn’t as critical to survival as other factors. Our ancestors could cut corners when it came to precise color vision, so some of them did.

Another is that, our ancestors were in large enough groups, such that some of the population could afford to be not as well off genetically, and still survive to procreate. This might also be why we have many other, and even deadly, genetic abnormalities.

There is also a factor of how the mutated gene is passed along. Without getting too complicated: Women (XX) are generally only carriers of X-linked mutations; but men (XY) will express the mutation, if they have it. In other words; if your mother is a carrier, and you’re male, there is a 50/50 chance that you’ll have the defective gene. For a woman to be colorblind, she must inherent that 50/50 mutation from her mother AND her father must have the mutated X chromosome. The fact that the genetics can therefore skip a generation, or even remain hidden for a few, plays a role in whether or not it is removed through evolutionary processes.

But what it really boils down to, is that modern medicine and the modern colorblind/deficient compatible world, beat out the forces of evolution. When you think about it, this isn’t very surprising or uncommon. Societies have been born, advanced, flourished, withered, and died faster than some speciation events can occur. We developed planes that can out-fly birds before we evolved wings, and therefore now we don’t need to evolve wings. So this begs to question, what has/can the modern world done/do to accommodate the colorblind/deficient?

 

Where (are we now):

You may have seen or heard about a video making the internet rounds where a colorblind man is given a set of EnChroma glasses, and for the first time “sees color”. It’s a very emotional video and one I won’t soon forget. However, I’ve looked into these glasses carefully, and while the company tends away from drastic claims (most of the time), what the glasses do is widely misunderstood.

As described above, the reason we colorblind/deficient people are the way we are, is because the retina (specifically the cones within the retina) at the back of the eye, cannot recognize light correctly. Glasses cannot fix this. What the glasses can do is alter the light that our eyes receive so that the wavelengths of light that we have trouble with, are different relative to all other incoming wavelengths. The company does a good job of explaining it here.

To put it simply, if I’m looking at blue flowers, with green stems, and brown dirt; I see blue flowers with a stem that blends into the dirt, both being a greenish/brownish color. These glass however will block out some of, say, the green from the stem; then I will see blue flowers and greenish stems with brownish dirt. The difference sounds small, and it kind of is, but the implications are anything but.

By making that small change in the light, I’d be able to see a difference in color where I didn’t before. The colors I’d be seeing are the same colors I had always been able to see (the retina/cones haven’t changed), but the new-found difference would be a very powerful illusion. And one with many practical applications, “…people with color blindness also noticed that the EnChroma lens helped them to differentiate textures within a single shade of color—for example the pattern of different shades of green on a leaf, or in a complex textures such as a hillside covered in trees may appear to be ‘less noisy’.” (SourceI am color blind–what does EnChroma do for me?).

 

Where (will we be):

I’m very fond of describing to friends and family this study. In which, squirrel monkeys, who were born red-green colorblind, were made regularly color-sighted. Basically to see if we could, and if so for how long. The experiments are discussed in more depth here and here. (The technical details can be a bit dense, but if you leave a comment or send me an email, I’d be happy to go into them to the best of my ability.)

For this article however, we’ll keep it simple. The retina’s were, in a way, tricked into creating cones that worked properly. The monkeys were tested by their ability to differentiate between red and green dots on a large touch-screen. When they pressed one color, nothing happened; when they pressed the other, they got a treat. This way if they consistently pressed, let’s say the green dots, they’d consistently get treats, and the researchers could tell they knew red from green. But if the odds were 50/50 of them getting a treat, the monkeys couldn’t see the color difference.

The effect has lasted for years since the study was first published (to my knowledge both monkeys still have regular site), and with little to no adverse effects. The procedure involved an injection into the retina, which can be scary sounding, but is totally painless.

The mechanism was essentially that a non-mutated version of the necessary gene was inserted into the cells of the retina, and when new cones were to be built, the new ‘blueprints’ were used; creating regularly functioning cones. For us humans, this means that if we could keep the human immune system from over-reacting (which is to-date the main concern), colorblindness/deficiency could be cured with a single injection into each eye. Which would be a huge accomplishment in modern medicine.

 

What (does that look like):

Ah yes, the almost unanimously asked question when someone learns you’re colorblind, “What does that look like?”. The only answer I (or anyone with such a mutation) can really give is, “Different.” That’s the simplest, and truest way I’ve found to describe how we view the world. If you Google around, there are numerous images that show “what it looks like to be colorblind” (as seen above in the ‘How’ section). But very rarely is the type of colorblindness specified, and almost never are things like lighting source, brightness, or surrounding colors, taken into consideration.

There’s an app called CVS Vision that’s free for Android devices, that uses specially built filters to simulate the different types of colorblindness, in real-time. But the key word there is “simulate”. I’ve heard of glasses that act basically as the opposite of the EnChroma glasses, “giving” regularly sighted people colorblindness, but again those are an approximation. View enough of these images, simulations, and approximations and you can wrap your head around the idea; but to actually view the difference, you’d need to intentionally, and very specifically, mutate your gene(s). In other words, you’d have to live it.

 

What (if):

I’ve been asked this one only a handful of times, “If you could fix your eyes, and see regularly, would you?”. I think the reason this one isn’t asked as much is because most people assume the answer is an obvious “Yes”. Or as the author of the squirrel monkey study has said, “People who are color-blind feel that they are missing out.” But this is not the case for me.

Realizing that it could be a post hoc (after-the-fact) type of reasoning; I point to my color blindness for my skeptical tendencies. I remember being quite young and realizing that if my own eyes could lie to me, anyone and anything could also lie, knowingly or not. Without getting into a personal diatribe, I would absolutely choose to keep my color-deficiency; if for no other reason then that it keeps me from forgetting that realization: Our senses are only an approximation. We are fallible, in all the ways we intuitively assume we cannot be. Our senses, memory, concept of self, and ability to separate reality from fiction; all of these can be fooled much more easily than we want to realize.

Also, there’s a type of nostalgia attached to my colorblindness. It’s always been with me, and it’s individual to me in many ways. It also connects me to my maternal grandfather (who also had Deuteranomaly and passed the gene onto me), as well as my uncle (who is also red-green colorblind although not blood-related to me). And for these reasons, I will always want my minor vision deficiency; even if the ‘cure’ is built on some freaking awesome science.


 

 

Thank you for your time, it was a long one, but I hope you enjoyed the read. If you have any questions, need clarification, or have a correction (especially a correction!), please leave a comment below, send it to the Feedback Page, or email me at Riley@dweebed.com

 


 

 

Sources:

http://news.ufl.edu/archive/2009/09/scientists-cure-color-blindness-in-monkeys.html

http://www.color-blindness.com/

http://enchroma.com/

https://cgwb.nci.nih.gov/cgi-bin/hgGene?hgsid=868294&db=hg19&hgg_gene=uc004fkb.3&hgg_chrom=chrX&hgg_start=153448084&hgg_end=153462352

(years of on and off research and personal experience.)

Riley Sproul has a Bachelors in Biology, with a concentration in PreMed, and a Chemistry Minor, from the University of Toledo. His goal is to obtain a Ph.D. in Neurobiology with in the next 4-5 years. His interests include sci-fi, PC-gaming, playing guitar, and a variety of other hobbies.
A Critical Thought: Colorblindness was last modified: June 6th, 2015 by Riley Sproul