Posted by 
Exploring the Differences Between Colorblindness Types and What Causes Them
By: Zachary Williams
The topic I chose to research was how color vision works, and what parts of the process of color perception is affected to cause color blindness, and what differences there are for people with color blindness. The class objective that this uses is from unit 6, and is “Explain how sensory cells translate stimulus into action potentials”.
Color blindness is caused when a person has a deficiency in their perception of color. There is a wide spectrum of color blindness, but all are caused by some kind of defect or malfunctioning of the cones in the eyes. The eyes contain three different types of cones, each of which corresponds to a different color of light (Red, Green, and Blue). Different combinations of the amount of each of these three colors are what give us the entire range of visible colors. A person with color blindness has a deficiency in one or more of these cones. The most common kind of color blindness is red/green colorblindness, and occurs when either the red or green cones are faulty in the eye. Red/green colorblindness has two varieties, protanopia (the absence of red cones) and deuteranopia (the absence of green cones). There also exists blue/yellow color blindness, in which the blue cone is absent (tritanopia), however this is a lot less common. The least common form of color blindness is the complete absence of cones, called achromatopsia, and people with this condition only see the world in shades of gray and also have very poor eyesight in general.
A study was run to test the impact that color saturation has on a visual search in people with color blindness. The results were quite interesting, and showcases how color blindness is a spectrum as opposed to either seeing or not seeing a color. During the unedited photos, people with normal color vision got 77.8% correct, while those with color vision deficiency only got 45.6%. For the photos that were edited to have higher color saturation, the percentage of correct answers rose from 45.6% to 46.9% (Hathibelagal 2023). Furthermore, Hathibelagal’s results show that protans (people with protanopia) performed significantly better than deutans (people with deuteranopia), specifically an average of 7.9% better (Hathibelagal 2023). The studies also found that it was primarily protans that did better with increased color saturation, specifically in images that featured red as a main color (Hathibelagal 2023). This study shows that color blindness exists on a spectrum, and people with a deficiency in one color doesn’t mean they can’t see that color at all. It also shows that accommodations are possible for people with color blindness and that there are ways to make it easier for people with color blindness to differentiate colors.
For my project, I decided to paint a scene that features a lot of colors, specifically reds and greens. The left half of the painting is painted normally, as though it were through the eyes of a person with normal color vision. The right side is painted as though it were through the eyes of a person with severe protanopia type red/green color blindness. The reds and oranges that make the left side so vibrant and colorful are all dull greens and grays on the right side, and the soft orange sunset is changed to a slightly harsher yellow in the sky. These are both representative of what the left side might look like through the eyes of someone with severe protanopia.
References:
Carroll, J., Neitz, M., Hofer, H., Neitz, J., & Williams, D. R. (2004). Functional photoreceptor loss revealed with adaptive optics: An alternate cause of color blindness. Proceedings of the National Academy of Sciences, 101(22), 8461–8466. https://doi.org/10.1073/pnas.0401440101
Hathibelagal, A. R. (2023). The impact of display saturation on visual search performance in congenital colour vision deficiency. PLOS ONE, 18(9). https://doi.org/10.1371/journal.pone.0290782
Turbert, D. (2024, September 10). What is color blindness?. American Academy of Ophthalmology. https://www.aao.org/eye-health/diseases/what-is-color-blindness
Color blindness: Types, causes & treatment. Cleveland Clinic. (2023, March 17). https://my.clevelandclinic.org/health/diseases/11604-color-blindness
^ Work in progress
This project explores how color vision works and what happens when the process is disrupted, leading to color blindness. Color vision relies on three types of cones in the retina, red, green, and blue which work together to create a range of visible colors. In color blindness, one or more of these cones are defective or missing, which affects how colors are perceived. The most common types are red/green color blindness, protanopia, and deuteranopia (missing green cones). Less common types include blue/yellow color blindness (tritanopia) and the rarest, achromatopsia, where no cones function at all, resulting in a grayscale world.
A study by Hathibelagal (2023) showed that color blindness exists on a spectrum. Those with color vision deficiencies performed worse on visual tasks compared to those with normal vision, but changes like increasing color saturation helped some individuals, especially those with protanopia. This highlights that people with color blindness don’t completely lack color perception and that accommodations can improve their experience.
To visualize this, this project includes a painting. The left side represents how people with normal vision see a colorful scene, while the right side shows the same scene as seen through the eyes of someone with severe protanopia. The vibrant reds and oranges on one side become muted greens and grays on the other, emphasizing how color blindness changes perception. This project utilizes art to make the effects of color blindness easier to understand.