Monochromacy – Complete Color Blindness
- Posted by Daniel Flück on July 20th, 2007 filed in Academic
- 17 Comments »
A lot of people think, if you suffer from color blindness you can not see any colors at all apart from black, white, and shades of gray. But they are wrong.
This form of complete color blindness is a very rare subtype of color vision deficiency among much more common ones like the the well known red-green color blindness. You might say, in this case the wording color blindness isn’t chosen appropriate—and you’re right.
Color Blindness begins when you don’t have normal human vision which might be only a very light change of color perception. And it ends with complete color blindness combined under the umbrella term monochromacy.
If you are suffering under monochromacy, you perceive everything just in shades of gray. This makes it really hard to accomplish many everyday tasks, because colors are such a central part of our life. For example, people suffering form monochromacy might mix up the following colors:
- green and blue
- red and black
- yellow and white
Monochromacy—also referred to as monochromatism—can be observed in different forms and even worse, many different names are in use:
- rod monochromacy: typical or complete achromatopsia, total color blindness, day blindness
- blue-cone monochromacy: S-cone monochromacy, incomplete achromatopsia
- cone monochromacy: complete achromatopsia with normal visual acuity
- cerebral achromatopsia: atypical achromatopsia
Before we dig a little deeper into the different forms of complete color blindness you should know the basics of vision and specially color vision.
The human eye has two different receptors inside the eye to perceive light. They are called photoreceptor cells. The rods are very sensitive on brightness and used for night vision. On the other side we have three different types of cones (trichromacy) which are responsible for colored day vision. The three different forms of cones have different peaks on color perception: red, green and blue. And the mixture of those three base colors makes us perceive such a huge variety of colors—or at least almost all of us. Compared to cones, rods play no role in color vision.
Rod Monochromacy
In this case your vision relies solely on the rods and the cones are usually not working at all. Some cases also report that the cones are absent, have some irregular distribution or that they show abnormal shapes. Occurrences are estimated to be between 1 : 30,000 and 1 : 50,000. But even if this numbers look very small, rod monochromacy is still by far the most common type of complete color blindness.
Rod monochromatism is often referred to as achromatopsia and is based on autosomal recessive inheritance. In other words, you need two defective chromosomes and it is equally distributed among men and women. Achromatopsia is characterized by the following symptoms:
- complete inability to differentiate colors,
- severe light sensitivity (photophobia),
- long-sightedness,
- involuntary eye movements (nystagmus),
- and central depressed vision (scotoma).
Also rod monochromats are completely colorblind, they often learn to associate certain colors with objects and to differentiate some colors by their brightness.
Blue-Cone Monochromacy
This rare form of monochromatism is caused by loss or rearrangement of the genes encoding L- and M-cones. Because of that only blue color receptors (S-cones) and rods are transmitting color and/or brightness information. If you suffer S-cone monochromacy your are usually completely colorblind. But in twilight situations—where rods and S-cones are working—color perception can be compared with dichromatic vision.
There are reports about very different forms of blue-cone monochromacy and it is sometimes not easy to differentiate it from rod monochromacy. No exact number of incidences is available. Scientists estimate the frequency at 1 : 100,000—for men. Because red and green cones are encoded on the sex chromosome, inheritance patterns are similar to red-green color blindness. Occurrences in women are unknown.
Cone Monochromacy
Also known as complete achromatopsia, this form is very rare. Only a few cases have been reported and none of them is fully accepted. It is assumed that they are either have working L- or M-cones and inactive or absent S-cones. Compared to blue-cone or rod monochromacy, cone monochromacy doesn’t have reduced visual acuity or any special light sensitivity.
Cerebral Achromatopsia
In this case optical examinations show normally functioning cones and rods. It is not understood in detail yet, but it is thought that the color receptors are working properly only the information is not reaching the brain or is not processed. Only a few cases have been investigated. Cerebral achromatopsia is unlike the other types of monochromacy not inherited but and acquired color vision defect. It may be caused by trauma or illness.
The academical background and many references on all types of monochromacy can be found in Opsin genes, cone photopigments, color vision, and color blindness by Sharpe et al. An internet information portal on achromatopsia is provided by the The Achromatopsia Network.
April 3rd, 2008 at 23:39
My son has been diagnosed with Blue-cone Monochromacy… I am a bit confused…. Can he see some colors or is he completely colorblind? Thank you for your time.
April 4th, 2008 at 7:50
Adrienne, in the eyes of a person with normal color vision, he is unfortunately completely colorblind. With blue-cone monochromacy he still has one type of cones available, but they won’t give him enough information to get a colorized picture. He will be able to distinguish at maximum a handful of different hues. Compared to normal color vision with more than one hunderd different hues this is almost nothing. He will make his color judgment almost solely based on brightness.
I wish you and your son all the best on your way. Try to connect with other people suffering the same, so you can exchance experiences. You might like to start with the achromatopsia network.
September 8th, 2008 at 22:38
Hi there,
i have recently been diagnosed with Rod monochromatopsia following about 6 comprehensive eye examinations. I have virtually no colour vision left following an accident which apparently has destroyed the part of my maclia which enbles me to see colour. ??(if this is the correct word) I have been told i can do nothing about it and will have to live with it. I cannot seem to get any answers but i found this website. Can i do anything??? can i be helped at all? I have seen these companies who offer colour vision enhancement contact lenses, but there are only 4 i can find and for 2 of them you have to travel to hungary or america. can you help any explain how i can obtain any of these lenses.
Many thanks
Christian Wilson
September 10th, 2008 at 21:51
Christian, thanks for sharing your story with us. Just a short note: It is either called monochromatism, monochromacy or achromatopsia.
Unfortunately I have to tell you that no color enhancing lenses can help to improve your color vision. This contacts can only shift your color perception and can’t really improve it.
So if you can’t see any hues anymore there is no system to feed this information back to your brain. There is only one possibility that time could maybe heal it and give you back some better color vision. But there is also only little chance for this.
I wish you all the best. Regards, Daniel.
October 25th, 2008 at 19:12
Hi!
I would like to share with you amazing works from a world know artist which suffers from achromatopsia.
you can GOOGLE or YAHOO his name.
his webpage is:
http://www.jaylonewolf.com
the latest press release is announcing his new exhibit in miami, florida. Oct 31st.
contact me for additional info.
November 1st, 2008 at 23:39
Hi Adrienne, I have bluecone monochromacy, I didnt know till i became a teenager, I am glad you have found out for your sons sake, life will be easier to understand knowing what the difference is, sadly, with the understanding, comes realization, but, at least we are not blind. Be thankful for that sight we have. A unique perspective of life he has been given. They say its not a disability, he will laugh at that. focus on an education that doesnt rely on color sighted needs, I have had many opportunities doors shut in my face. With planning you an he can avoid that. Good Luck, feel free to contact me anytime if you have a question, not that i have any answers, Todd, Valerk8@hotmail.com
January 4th, 2009 at 21:36
[...] Lonewolf Morales is a painter who suffers from congenital monochromacy, complete colorblindness… but he has used that disability to his advantage. He paints very [...]
March 3rd, 2009 at 23:49
Hi, my husband is completely color blind but we are not sure waht it is called… I didn’t believe him because I had never heard of it. Now that I have researched it a lot of his behavior makes sense, like his love for pandas and his hate of myself wearing face powder. Is there anything we can do to reduce his light sensitivity???
May 24th, 2009 at 20:55
I have a question. Are all forms color blindness located on the X-chromosomes? I’m not talking about the diseases that lead to Color Blindness (i.e. Retina Pigmentosa) . I just want to know if the Genes controlling color perception are all located on the X-chromosome. Thanks:)
May 25th, 2009 at 8:56
Peter: No, they are not only located on the X chromosomes. Have a look at the article Chromosomes involved in Color Blindness to learn more about this.
May 31st, 2009 at 13:54
Hi,
My father in-law is totally colour blind, though I don’t think he’d ever get tested. He squints a fair bit in the sun, but seems to have a great eye for detail. Hasn’t stopped him being a boiler-maker, then owning an engineering company, then designing feed-lots, then selling farms (drives a crazy number of km’s in a year). It’s always a laugh when he comes back having bought a few new shirts though (I think the shop assistants take the opportunity to unload stock that could sell to no one else)… My wife is also colour blind, but only slightly. She only has trouble with colours that are very dark, or very light. I’ve been told that any boys we have will be colour-blind. Whats the chances that it will be extreme like my father in-law (sounds pretty unlikely), or nearly insignificant like my wife (except for those darn numbers in dots that drive her nuts. Sorry beautiful, it’s not 24… it’s a boat…)? All her brothers who have been tested are also colour blind (family of eight), as well as one of her sisters. No colour blindness in my family.
June 5th, 2009 at 21:05
Ben, only red-green color blindness is encoded on the X sex chromosome. So if you are really talking about some form of total color blindness, I can’t really tell you what the chances for your children are.
But as it looks like it doesn’t really matter any way – your father and your wife seem to get a long very well.
September 17th, 2009 at 9:15
[...] #15 There are people which are really suffering from complete color blindness, which is called achromatopsia or monochromacy. [...]
September 29th, 2009 at 0:01
Love the site. As a pretty severe red-green color weak guy one of the most frustrating aspects is attempting to explain to others what things look like. Any additional comparison images would be very very helpfull. Thanks!
October 27th, 2009 at 19:54
My son has blue cone monochromacy and he will be turning 16 soon. He is watching all of his friends get their driving permits and licenses. His low vision and color blindness has never had such an emotional effect on him until lately. With yesterday’s news of the successful gene replacement therapy in the 9 year old boy, I have been searching the internet all day today looking for a clinical trial for my son. I was able to read that a trial for achromatopsia is going to be open soon. Will blue cone monochromacy qualify for the achromatopsia trial? Also, if you know of any blog specifically for BCM, could you please forward me the link?
Any parents with children diagnosed with this disorder can feel free to contact me directly through email at hdanna@uninets.net. I was told that this is a disorder that has only been linked to my family; therefore, I’m guessing that if we did the genealogy, we may discover that we are related.
November 10th, 2009 at 4:36
My son was involved in a traumatic brain injury 2 years ago.
At first all colors were very bright and then everything faded to black and white and has been that way ever since. It has been mentioned that he may suffer from Cerebral Achromatopsia, but so little seems to be known that they don’t even feel comfortable giving that diagnosis.
Any information that we can obtain, especially as it may relate to him some day getting his color vision back, would be greatly appreciated.
January 4th, 2010 at 15:59
My mother was born completely color blind and legally blind. Is this the same thing. Her sister a year older then here has the same condition, they are the only 2 out of 5 kids (with one being a boy) in the family with this. Neither parent are color blind. My mother has never given me a diognosis of her sight, she gets upset. Any help??