Protanomaly and Deuteranomaly and Colorblindness, Oh My!

My father wears shades of blue almost exclusively. That’s because my mother always bought his clothes in shades of blue. And that is because neither of them wanted her to have to dress him every morning – she didn’t much want to and frankly he wouldn’t have stood for it. You see, my father is colorblind and cannot see most shades of red and green. Blue, he can see, so blue is what he wears.

Mothering a Colorblind Son

You might expect a fourteen-year-old boy to get around the kitchen pretty well independently. My son, however, brings me bananas to check whether or not they are too green to eat.

We also have an understanding that he’ll check with me or his older sister before making a sandwich … since the time I caught him about to bite into a slice of ham that was turned mostly green. For that matter, he can check with his younger siblings too!

Yes, my oldest son is also colorblind, like my father.

When we hiked up an old volcano recently, the black volcanic gravel was studded with these lovely plants with vivid rosy-red petals. He could see the plants clearly, but no red flowers. When standing very close, he could distinguish that there was a difference in the red from the green.

It reminded me of a story my mom told about my dad, when they were standing in a field filled with Indian paintbrushes, a vivid red flower. He couldn’t see them at all until she touched one, and then the whole field sprang to life and he could see them all. Not the red, he still couldn’t see that; but he had spotted the slight difference and could suddenly perceive it all around him.

How Do They Get It?

My father is colorblind, so my son inherited his red-green deficiencies from him – through me, though my color vision is normal. Over 95 percent of colorblindness is red-green deficiency and is hereditary: women carry it, but men manifest it.

I have two girls and two boys. My son with normal color vision cannot be a carrier. My son with colorblindness will be able to pass the gene on to his daughters, as my father did, and they may be carriers but are unlikely to have color deficiencies themselves; my two daughters who both have perfect color vision may be carriers as well.

My son’s sons will have normal color vision, unless their own mother is a carrier.

My sister has a son who is not colorblind, but she may still be a carrier and have passed it on to her own daughters. Thus it can skip generations and show up unexpectedly in great-great grandchildren!

A much smaller percentage of colorblindness, around four percent, is a blue-yellow deficiency and is not sex-linked or hereditary. Instead it is caused by a simple mutation of the gene and affects men and women equally.

Less than one percent of colorblind people have full-spectrum color blindness and see only shades of gray.

Approximately eight to ten percent of the male population in total is affected with colorblindness, while less than one percent of women are affected. A woman would need both a colorblind father and a mother who is a carrier to have a chance of being colorblind herself – hence the far lower incidence of colorblind women.

What Can They See?

It’s not “all or nothing.” Even among those with red-green colorblindness, exactly what they see can vary widely. Some, like my son, can see some shades of red or green. Some, like my son, have color depth perception problems: dark shades of deep green appear black to him, and two sets of towels we have that are light green and a sandy color, about the same depth of color to each, are perfectly indistinguishable to him.

Strangely, some shades of very light green appear to be red or pink to him!

I find it especially interesting that my son can rarely see purple. My speculation is that his red perception is so weak, all he sees is the blue. Almost any shade of purple is blue to him.


Many games present difficulties for my son (and my father). Set is a wonderful game we all enjoy, but as a game of visual perception with the goal of spotting sets of three cards – color being one of the distinguishing characteristics of any set – he is severely hampered in spotting them quickly. Trivial Pursuit is another color-dependent game that is often a problem for people with colorblindness.

Colorblindness can create actual danger in some situations. 

Traffic lights, for instance, are red, green, and yellow, and may have little differentiation to someone with severe color perception problems.

My son informs us that these two images of a traffic light look exactly the same.

Many traffic lights add orange to the red, and make the green from a yellow light with a blue filter, in order to help colorblind drivers perceive the colors, and of course knowing that red is on top is the primary way they know if the stop or go light is on. It was a problem for my dad when he started driving, because the red-on-top format was not always the norm then as it is now.

In other situations, colorblindness may turn out to be a boon: colorblind soldiers often can see through camouflage to perceive what the enemy is trying to hide.

What Were Those Funny Words in the Title?

Protanopy means the red receptor is affected. Deuteranopy, the most common form and the one that affects my son, means the green receptor is affected. Both conditions affect both red and green vision, but with slightly differing effects.

I recently came across some speculation that Van Gogh may have been colorblind. Looking at his paintings under filters changes the colors to a more normal-looking palette.

They also have now made filters to help us to see the way my son does! When we upload a photo to Asada’s Image Converter and switch between the “normal” and “deuteranope” settings, he cannot see any difference in most of the “normal” images compared to the filtered ones.

And finally, we can see why the game Set is so problematic for him! Blue, a dark yellowish brown, and a more sandy brown. No wonder it takes him a while to find matching sets!

My mother died sixteen years ago and my father remarried. His new wife didn’t seem to mind dressing him, or at least scolding him when his clothing didn’t match: she bought or allowed him to buy clothing in all sorts of shades.

After her death, when my sister and I were helping clean out her stuff, we took the time to go through our dad’s wardrobe, and he can now once again dress all in his favorite color, the one he can see and wear without worry that he’s offending the fashion police: blue.




We Are Color Blind is dedicated to making the internet a better place for color blind users. Don’t miss the humorous essay On dinner plates, green cats, and my grandfather.

Testing Color Vision is a helpful site with FAQs, tests, and informative articles.

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