SCIENCE in your LIFE
Colorblindness
By L.O.
We might think that colors are common knowledge, but somewhere around 8% of men and 0.4% of women have some type of colorblindness. Normal vision is trichromatic, which sees three colors, red, green, and blue, and their various combinations. Most colorblind people are dichromats, in that they can see two of those three colors but have problems with the other color. Around 75% of people with colorblindness have issues seeing the color green, while most of the rest have problems seeing red.
In your eye, rod cells detect light and cone cells detect color. Cone cells use three stacked light-sensitive pigments to detect color; these pigments are called opsins. The first, long-wave opsin detects red and the higher parts of the visible spectrum around 561nm in wavelength. Next, the medium-wave opsin picks up green light at 531nm. Finally, the short-wave opsin absorbs blue light at the lower end of the spectrum around 430nm.
A mutation with an opsin can cause issues with perceiving color. This is known as a trichromatic anomaly, and a deficiency in a particular opsin is described with a term for that the type of colorblindness. Protanomaly is a mutation to long-wave opsins, deutanomaly refers to mutations in the medium-wave opsins, and tritoanomaly means a mutation happened to short-wave opsins. Additionally, coloblindnesss can be complete or partial, and is referred to with, “-opia,” and, “-anomaly,” respectively.
Colorblindness is usually inherited from your parents. The genes that make the long-wave opsin and the medium-wave opsin are sex-linked traits found on the X-chromosome. This is why men are more likely to have red-green color deficiencies than women, since they only have one copy of an X-chromosome. This doesn’t happen with the short-wave opsin, and so issues are much less common, only in about 0.01% of both men and women.
Keene, Douglas R. “A Review of Color Blindness for Microscopists: Guidelines and Tools for Accommodating and Coping with Color Vision Deficiency.” Microscopy and Microanalysis, vol. 21, no. 02, May 2015, pp. 279–289., doi:10.1017/s1431927615000173.
Please send any questions or comments to Dr. Spitzer (spitzern@marshall.edu )
Note: Any opinions expressed in these articles are those of the individual authors and do not necessarily represent those of Dr. Spitzer, the Department of Biological Sciences, or Marshall University.