Colour blindness

health Jan 31, 2023

The retina of eye contains two types of photoreceptor cells called rods and cones. Rods are responsible for night vision and cones are responsible for colour vision.
The defect in cone cells causes decreased ability to see color or differences in color. Such a condition is called colour blind.
Color blindness is also called Daltonism, after the scientist John Dalton who was also colorblind himself and published the first scientific article about color blindness.
According to an estimation, 300 million people in the world are color blind.
Nearly, 8% of men and less than 1% of women are affected by Color blindness.
95% of the color blind people are men and 98% of those with color blindness have red-green color blindness.
The most common form of color vision deficiency is Red-green color vision in which affected individuals are unable to distinguish between some shades of red, yellow, and green. In red-green color-blindness, red and green are seen as the same color. It is sex linked.
The rare form of color vision deficiency is Blue-yellow color vision which causes difficulty in distinguishing dark blue from black.
Blue-yellow color blindness is not sex linked, so both men and women are equally affected.
Complete colorblind is very rare and they can see only gray or black and white.
Color blindness can be inherited or acquired.
Inherited Color blindness is due to the genetic disorder and it is commonly inherited from mutations on the X chromosome.
If a woman is colorblind, all her sons will also be colorblind.
Father can’t pass his red-green color blindness on to his sons.
Inherited color blindness can be congenital (from birth), or it can commence in childhood or adulthood. Depending on the mutation, it can be stationary, and remain the same throughout life, or it can be progressive.

Acquired color blindness develops due to the physical or chemical damage to the eye, optic nerve or parts of the brain caused by accidents and other traumas.

Risk factors for color blindness

Men are at higher risk for being born with color blindness than women.
certain conditions which may increase risk for acquired color deficiency are,

  • glaucoma
  • retinal damage caused by diabetes
  • age-related macular degeneration
  • Alzheimer’s disease
  • Parkinson’s disease
  • chronic alcoholism
  • Vitamin A deficiency
  • leukemia, and sickle cell anemia
  • certain drugs such as hydroxychloroquine (Plaquenil) used to treat rheumatoid arthritis, and drugs used in the treatment of tuberculosis, malaria
  • long-time exposure to solvent vapors

There is no known cure for color blindness. Contact lenses and glasses are available with filters to help color deficiencies.
Many mobile and computer applications have been developed to help color blind individuals to differentiate between colors.
the most famous jobs which require normal color vision are Police officer, firefighter, and airline pilot
The International Colour Vision Society is scientifically investigating every aspect of color vision and color vision deficiency.
Many colorblind people have problems with matching clothes and buying ripe bananas.
Facebook is blue because  founder, Mark Zuckerberg, suffers from red-green color blindness.
Dogs, cats and rabbits can see mostly gray colour. Monkeys have strong color vision while bees and butterflies have superior vision and can see colors humans can’t even see.


A. Sandhya

M.Sc Zoology

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