It’s actually more complex than that. There are different types of color blindness, and whether or not you have it is almost always dictated by your genes.
Color blindness is largely determined by a recessive gene on the X chromosome. This means that women need two copies of the gene to actually be colorblind but they can be carriers with no symptoms if they only have one copy, whereas men will be colorblind if their single X chromosome contains the gene. As a result, around eight percent of men are colorblind, compared to less than one percent of women.
There are two types of light-sensitive cells in our retinas: rods and cones. Rods enable us to see in low-light conditions, while cones enable us to see colors. Our color vision is trichromatic, meaning we have cones that are specifically sensitive to long (red), medium (green), and short (blue) wavelengths of light. Color blindness is what happens when one or more of these types of cones don’t work the way they should.
The most common type of color blindness is red/green. Because red and green are opposite colors, you’ll be red/green colorblind whether it’s the green cones that aren’t working (deuteranomaly) or the red cones (protanomaly). The result is about the same either way: colors with red or green in them appear duller or yellowish brown.
Much more rare is blue/yellow color blindness (tritanopia), which happens when the blue cones are the ones that don’t work properly. This results in a visual landscape of pinks, teals, and browns.
Even rarer than red/green and blue/yellow color blindness is monochromacy, or complete color blindness. People with monochromatic vision can only see in shades of gray. They tend to be extremely sensitive to light. Because cones are what give us sharp detail in our vision, monochromacy can also mean that vision will be fuzzy overall.
Fun fact: many animals, including dogs, have red/green color blindness. They mostly see in yellows, blues, and grays. The idea of enraging a bull using a red cape is erroneous, because bulls can’t see the color red!
Within red/green and blue/yellow color blindness, there are still important distinctions in how it happens. You could be dichromatic, meaning your eyes completely lack a type of cone, or you could be an anomalous trichromat, meaning your cones simply overlap too much in what stimulates them.
Anomalous trichromacy is more common, and if the overlap isn’t too severe, the color blindness can be counteracted with special glasses designed to block out the wavelengths of light that trigger both types of cones.
Check out this video to see how these glasses work:
If you’ve been living with a type of color blindness, there are plenty of resources available to you to make life in a trichromatic society easier. Schedule an appointment with us so that we can get you what you need!