“The Green Lantern”. “Yellow Submarine”. “Purple Rain”. “The Scarlet Letter”.
Without color, it’s all just “Fifty Shades of Gray”. To paraphrase Walt Disney, our world is a carousel of color! Blue skies, green grass, red roses, purple orchids. Rainbows! But. What if we can’t see color correctly? What if we have a condition that causes a color vision deficiency. Color “blindness” if you will.
Well, then. Things would appear quite different indeed.
Total color blindness – called achromatopsia – is rare. It affects only about 1 in 33,000 people. Those affected are able to distinguish black, white and varying shades of gray.
Conversely, the most common color vision deficiency (CVD) is red-green. Does that mean that red and green are the only colors one can see? Or does it mean that red and green are completely missing from the color spectrum? Do people who are red-green deficient see those colors as gray or black?
None of the above, actually. Most often, folks who are red-green deficient simply struggle to differentiate the two shades. Often, the colors are muted to the point where they really can’t be distinguished and appear as color-tinged mud.
If someone is blue-yellow deficient, they will often have issues with red and green, as well.
Go back to your first grade color wheel. Combine blue and yellow. What do you get? Uh-huh. Green. See how this all comes together? This type of deficiency is rarer and results in neutral or gray areas instead of the colors.
So. How do we see color? What is color?
Color in its most simple form is light. How an object interacts with light is how it gets its color and that, along with certain structures within our eyes, is how we perceive it. 
As with most everything that we see, our eyes and brain work together to translate light into color.
Inside your eyes, way at the back, are tiny photosensors made up of cells called rods and cones. Rod cells are the most sensitive to low light while the cones are responsive to bright light. They are concentrated in a very small spot – about 0.3 millimeters – on the retina called the fovea. We have about 7 million cones and nearly all of them are found in this teeny area!
They are small, but mighty.
The cones don’t all perform the same duties. Over half – about 64% – respond to red light, about one third to green light and only about 2% to blue light. Color blindness is caused by a glitch in how our cones respond to light.
Most color deficiencies are genetic. They pass down through our ancestral lines.
The red-green deficiency is passed through the X chromosome. Women carry two X chromosomes, and both would have to carry the defect in order for a woman to be red-green deficient. Since men carry only one X chromosome, it is easier for them to be affected. And, as men are more prone to the red-green deficiency, it is more often passed through the generations. That’s why men are more likely to carry and pass on the defect.
Other causes of color vision deficiency include injury, brain and nervous system disorders, eye disease and some medications such as hydroxychloroquine.
Overall, about 8% of all men are affected by some form of color deficiency while less than 1% of women are.
Keep in mind that most forms of CVD allow you see color, just in a muted or indistinguishable form.
Total color loss, again, is very rare. There are those who have “incomplete” achromatopsia and these people have the ability to see some form of colors.
Canadian drummer Karl Schwonick has achromatopsia. When people comment to him that “it must suck” to not see color, his response is, “I’ve never seen it, so I don’t know.”
Complete achromatopsia is often accompanied by other vision disturbances such extreme light sensitivity, reduced visual acuity and a condition called “nystagmus” which causes the eyes to shake – almost seeming to vibrate in severe cases.
Color vision deficiency cannot be cured, though there are lenses that claim to improve a person’s color perception. These lenses are not without drawbacks and, for some people, the sudden vibrancy of color can be a little overwhelming.
So how do I know if I have a color deficiency? If it’s hereditary, I never had “normal” color vision, so I may not know what I’m missing.
That’s true. People born without the ability to do something don’t miss it since they never had it to begin with. Like the drummer.
The most common color vision test is the Ishihara Color Plate Test. Though it’s been around for over 100 years, it is still the most widely used by eye doctors. 
The plates were introduced in 1917 by Doctor Shinobu Ishihara and they consist of colored dots that reveal either numbers or a path. Your responses to the Ishihara plates will help your eye doctor determine if you have a color deficiency and, if so, what colors are involved.
Well. What if I do have a deficiency? How will this change my world? Why would it be an issue?
Besides the obvious problems with wardrobe and painting your living room, there are many careers that can be out of reach for a person with CVD.
Electricians must be able to differentiate the colors of the wires that they use.
Boat captains rely on red and green channel markers for navigation and share a need to distinguish control panel lights with military pilots.
Even chefs and florists depend heavily upon color interpretation. After all, presentation is everything!
Oddly, traffic signals are rarely an issue since the “Stop”, “Caution” and “Go” lights are arranged in a consistent order. Once you know that order, you’re good to go. Or stop…
While color deficiency may cause you to make some adjustments, living with CVD is not impossible. There are visual aids, training and technology to make life easier for most people with color deficiencies.
If you have concerns, give us a call. We’re here to answer whatever questions you might have.
Remember, Hollywood Eyes is still following COVID-19 protocol. All visits are by appointment only and we do require masks be worn in the office.
