Tritanopia – Blue-Yellow Color Blindness
- Posted by Daniel Flück on May 8th, 2006 filed in Academic
Actually the wording blue-yellow color blindness is misleading. People affected by tritan color blindness confuse blue with green and yellow with violet. So the term blue-green color blindness would be more accurate because the colors blue and yellow are usually not mixed up by tritanopes.
Tritan defects affect the short-wavelength cone (S-cone). There are two different types which can be observed:
- Tritanopia: People affected by tritanopia are dichromats. This means the S-cones are completely missing and only long- and medium-wavelength cones are present.
- Tritanomaly: This is an alleviated form of blue-yellow color blindness, where the S-cones are present but do have some kind of mutation.
Blue-yellow color blindness can be observed only very rarely. Different studies diverge a lot in the numbers but as a rule of thumb you could say one out of 10′000 persons is affected at most. In contrary to red-green color blindness tritan defects are autosomal and encoded on chromosome 7. This means tritanopia and tritanomaly are not sex-linked traits and therefore women and men are equally affected.
It can be observed that triatnopes usually have fewer problems in performing everyday tasks than do those with red-green dichromacy. Maybe this is because our society associates green with good/go and red with bad/stop, a pair of colors which accompanies us every day but a clear reason isn’t found yet by the researchers.
Tritan defects can not only be inherited but also acquired during one’s lifetime. In this case it even may be reversible and not permanent like an inherited color blindness. In the case of an acquired defect this is either evolving slowly for example simply through aging or coming instantly caused by a hard hit on your head.
- Because the eye lens becomes less transparent with age, this can cause very light tritanomalous symptoms. Usually they are not serious enough for a positive diagnosis on color blindness.
- Among alcoholics a higher incidence rate of tritanopia could be counted. Large quantities of alcohol resulted in poorer color discrimination in all spectra but with significantly more errors in the blue-yellow versus the red-green color range.
- Mixtures of organic solvents even at low concentrations may also impair color vision. Errors were measured mainly in the blue-yellow color spectrum.
- An injury through a hard hit to the front of back of your head may also cause blue-yellow color blindness. An example story can be found at Tritanopic after Heas Injury.
The two photographs below give you some impression what tritanopes see. On the right side the actual photograph is shown as it is seen by people with normal color vision. On the right side you see the tritan counterpart where you can spot how blue-yellow color blindness influences the view of colors.
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Read more about Deuteranopia and Protanopia—the other two types of color blindness.
Further readings:
Opsin Genes, Cone Photopigments, Color Vision, and Color Blindness
Does Occupational Exposure to Organic Solvents Affect Colour Vision?
Wikipedia: Color Blindness
Related articles:
The Biology behind Red-Green Color Blindness
Colorblind Population
January 3rd, 2007 at 18:23
i have tritanopia except for me i can see green perfectly, this would mean i have a tritanomalous effect seeing as i am not a complete trichomat. however on my med certificate i am put down as tritanope. this may mean that tritanope can range in different effects for different people.
January 4th, 2007 at 11:35
Digby, thanks a lot for your insights in your own color blindness. As you say I also think that there are many different shades of color blindness and it’s not easy to exactly determine ones severeness of color blindness. I’m also suffering a strong protanomaly but am not sure if it’s protanopia or a protanomalous effect. It would be interesting to find a good test which can clearify if you are a dichromat or a trichromat.
January 13th, 2007 at 23:34
Both my wife and her mother suffer from tritanopia, although the tritanopia is much less severe in my wife’s mother. They are both Filipinas, and I noticed with interest the mention above of exposure to organic solvents being a possible cause of tritanopia. Applying kerosene on the stomach to treat stomach maladies is a common practice in the Philippines, and it would be interesting to see if there is a higher rate of tritanopia there, and if this is due to genetics or environmental factors.
January 14th, 2007 at 20:56
Daniel, it’s interesting to read about the color blindness of your wife and her mother and how you think it could be connected to a Philippinian practice. Unfortunately I can’t tell you if there is a higher rate of tritanopia there and what its cause would be. This would definitely be an interesting topic to get further into detail. If I’ll find out more about it, I’ll post it on Colblindor.
March 26th, 2007 at 2:55
You need to better define what you call “moral conduct” and to quote your sources for this outrageous claim. It currently reads like 19th century superstition.
March 29th, 2007 at 13:11
Thanks. I changed the paragraph and I hope this made it clearer.
May 15th, 2007 at 17:56
My son will be four this year….It appears that he sees and can recognize all colors except for certain blues and greens. Sometimes he can point out a deep blue, however he often mixes up lighter shades of each. Is this Tritanopia? Or some version of it?
May 17th, 2007 at 21:09
Good question val. I tried to summarize my point of view at Mixing Up Blue and Green and I hope this is some kind of answer for you.
Anyway, all the best with your boy and don’t make up your mind to much about it, color blindness is often not that a big issue to a child.
May 29th, 2007 at 13:02
But surely there’s some kind of procedure that can determine what kind of colour blindness you have without being tested. (excuse my spelling)
May 31st, 2007 at 21:36
Digby, talking about online tests, I don’t think there are color blindness tests which are reliable enough.
And even when you visit an eye specialist, he needs some special instruments like the anomaloscope to get some good results.
There are tests to answer the question of dichromcy vs. anomalous trichromacy, but it’s not easily done.
August 17th, 2007 at 10:00
[…] color gaps suggest tritanomaly (low blue […]
October 5th, 2007 at 9:33
i don’t quite grasp everything about colorblindness so i don’t know if i’m color blind or not. i have great difficulty telling the difference between certain shades of greens, blues, black, greys and purples. does this have anything to do with being color blind?
October 5th, 2007 at 19:50
Stephanie, what you wrote down is exactly what color blindness is. It’s not about seeing no colors, but having problems with certain shades.
Try the Ishihara Plates Color Blindness Test in a Leaflet or one of the other tests. If you can’t see all the numbers, you are to some degree colorblind.
October 30th, 2007 at 13:32
Thanks for a very informative site. My 3yr old son is constantly mixing up Blue and green, but is fine with all other colours. Although he is still quite young to positively determine a form of colour blindness, its handy to be well informed of Tritanopia before we consult our local GP if necessary when hes older.
December 18th, 2007 at 3:20
My daughter, like Digby above, is almost 3 years old and can see every color except yellow, which she refers to as pink or purple. I’ve tested it many times with her and she answers the same every time. Should I take her to an eye specialist for this? Are there any eyeglasses/lenses, procedures, or cures for this type of colorblindness or is it something she just needs to live with for the rest of her life?
Thanks in advance for your help with this!
December 18th, 2007 at 8:34
Debi, thanks for your questions which I’ll try to answer with the following points:
1) Don’t take her to the eye specialist yet. Personally I think it is to early. Let her some more time to develop a proper understanding of colors.
2) Yes, there are glasses or lenses. But they can’t correct color vision but just shift the problem to another area (and they are quite expensive).
3) Otherwise, there is no cure in sight. So yes, she would have to live with it her whole life (unless it is an acquired form, which can sometimes “heal”).
But, if you don’t have a history of tritanopia in your family, the chances are extremly low for her to have it. So give her and you yourself some more time.
December 29th, 2007 at 11:06
Ok, just found out that my cousin is tritanomalous! im really excited because i never thought i would meet someone else with any form of tritanopia because it is so rare. But now my friend who is a girl is claiming to mix up greens with aqua at traffic lights and mixes up yellows with whites or light violets. what are the chances of meeting TWO other people with tritanopia? (I am tritanopic by the way!)
January 8th, 2008 at 4:41
Hey Debi!
I can’t see yellow either (especially yellow highlighters) I mix it up with pink. There’s a thought!
She probably has tritanopia. It’s not that bad. Half the time i forget i have it cause there’s no problems in life. (except yellow highlighters lol)
January 14th, 2008 at 4:41
I just recieved 6 courses of ECT for major depression and it cured my tritanopia that I have had since my first memory of the day I hit my head on the gold painted radiator in my parents old house when the babysitter was watching me. That was 35 years ago. I have had blue yellow color perception problems since. I could see blue and yellow but not where I was supposed to and not with the intensity I was supposed to- if that makes sense. I thought my hat was aqua it was light minty green this whole time! And yellow has looked very dull- my son got a Tonka dump truck for Christmas- Before ECT I would have thought it was light yellow but is not it so bright!!! Please someone e-mail me- to find out I was color blind all these years and i have been a floral designer too. I also have a son who has autism maybe he has tritanopia, because I have other sensory problems that are now cured by ECT- like I can hear and it doesn’t sound as if people are in a tunnel. I can taste and feel things correctly now. Please someone out there who has had their senses altered let me know. They told me ECT could be miraculous for depression but I didn’t know just how miraculous it was- it has taken me out of PDD-NOS. And cured my colored blindness. This is amazing. Wanda
January 14th, 2008 at 4:45
I always thought that the count on sesame st. was like a fleshy color but he is not he is lavender!! I can’t believe this.
January 15th, 2008 at 12:50
wanda what’s you’re email, I got my tritanopia from a bang on the head in 2002, (at least i think) I really want to be cured!
January 16th, 2008 at 18:37
I just came home from visiting the florist I work at and to see all the designs I created while color blind is amazing because they all look very good and the colors go together so well. Whoever taught me colors as a child must have done a good job.
February 25th, 2008 at 21:25
While doing a project on colorblindness in my ap biology class I came acrossed this site. My fiance is colorblind; however, it has been difficult to try and figure out what type of colorblindness he has. He can see most reds and greens (he only has problems seeing reds and greens that are bright like lime green)but he has problems telling the difference between blues and purples. He claims that they look almost gray to him. He and I would like to find out what type of colorblindness he has. If anyone has an answer please reply back to me.
thank you!!!
February 27th, 2008 at 20:26
Devin, let your fiance do the following color blindness test. This should tell you more about the type of color blindness he is suffering from: Protanopia, Deuteranopia (both red-green color blindness), or Tritanopia (blue-yellow color blindness).
March 2nd, 2008 at 21:16
[…] Así es como ve un gay daltónico su bandera. En realidad, todos los daltónicos, aunque no sean gays. Bueno, más exactamente un tipo de daltónicos, porque hay tantos tipos como personas aunque los agrupan en tres tipos, según con qué color tengan problemas: con el rojo y el verde o con el amarillo y el azul. […]
March 3rd, 2008 at 8:40
My 3 year-old daughter recognizes all colors except for yellow. She calls yellow “blue”. But when shown the color blue she knows it’s blue. Could this be Tritanopia?
March 3rd, 2008 at 9:26
Christel, I think 3 years is to early to judge. Read my article about color blindness and young children.
April 6th, 2008 at 5:02
Yes, my son is 3 plus years old. Recently both me and his nursery teachers realised that he is not able to identiy yellow, he keeps calling them blue.
I recalled him able to identify the yellows sometime back, but not now. There is also no significant head injury to him. I am concerned as all mothers do, but he is still young and I intend to observe him for a longer while before I bring him to any medical specialist (hopefully there is one availble in my area).
April 8th, 2008 at 15:24
My daughter will be 4 in a month and in preschool. She knows all her colors but consistantly mistakes yellow for blue. She will go through all the colors and when yellow comes up it’s blue…then when we don’t say yes, she’ll say another color and then yellow. This has been ongoing for over a year.
Any suggestions?
April 8th, 2008 at 22:19
The problem is, that young children can’t accurately name colors. They have to learn it like numbers and letters and this isn’t that easy. So just by naming colors wrong, you can’t judge about color blindness in a young child.
Why don’t you try the following test: Buy a box of crayons including many different shades of colors. Now let your child paint things. Try to give him or her the wrong crayon without naming the color. Will he/she color the sky maybe green or yellow? Or a blue sun? If he/she is just mixing up certain colors but can use all the others correctly this is a hint for color blindness. If he/she can’t use them correctly at all it’s to early to judge.
Regards, Daniel.
May 31st, 2008 at 8:44
Hi, i just discovered that I am colorblind after taking the ISHIHARA COLOR BLINDNESS TEST. Do you have any idea how much is the contact lens that I need in case there is really one that can help me improve my vision?thanks.
June 2nd, 2008 at 20:14
Bryan, have a look at the following article Improving Color Vision with Lenses for the Colorblind. Unfortunately I can’t give correct prices, but there are some hints in the comments section.