We’re all taught in school the seven colors of the rainbow: red, orange, yellow, green, blue, violet, and indigo. But for people with color blindness, these seven don’t pop so distinctly. While they can still see a rainbow, it may not be as vivid or striated as it would be to someone with ‘normal’ vision.

Despite its colloquial name, the condition formally known as deficient color vision is simply a different way of seeing color — which in its own way is still a fulfilling, albeit, different sensory experience. For instance, Facebook founder Mark Zuckerberg, who is red-green color blind, has said he chose the color blue for his brand because “blue is the richest color for me — I can see all of blue.”

What is color blindness?

Color blindness, known formally as deficient color vision, refers to a group of conditions that impair the ability to distinguish between certain colors, or in rarer cases, impair the ability to see any colors at all — which means perceiving the world as black and white.

But color blindness, though a popular term, is a bit of a misnomer; research suggests that color blindness may actually give people enhanced perception of some colors even though they cannot distinguish others. In fact, during the second world war, color-blind observers were appointed to penetrate camouflage.

What are the different types of color blindness?

Color blindness can range from mild to moderate to severe, and some individuals simply struggle to differentiate color pairs (and their related hues), while others cannot actually perceive a difference between colors. Color blindness exists as three different conditions:

• Red-Green color blindness: This is the most common form of color blindness and includes reduced sensitivity to either red, green, or both colors. People who experience this form of color blindness are unable to distinguish between red and green, and also struggle to correctly perceive any color that contains red or green hues, such as purple, pink, or orange.
• Blue-Yellow color blindness: This form of color blindness can diminish or alter a person’s ability to distinguish some blues from greens, and yellows from violet, red, or pink. It can also make colors look less bright than they are.
• Complete color blindness: Called monochromacy or achromatopsia, complete color blindness causes people to perceive the world in black and white shades. It can also cause them to be uncomfortable in bright environments.

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What causes color blindness?

The eye’s retina comprises two different types of cells: rods and cones. Cones are responsible for color vision, among other things; the three types of cones are each filled with a different pigment that is sensitive to a different wavelength of light.

For most people with color blindness, the condition is genetic, occurring when a mutation causes them to lack one or more types of cones or affects their pigment production.

However, non-hereditary factors can also make people color blind. Damage to the eye or optic nerve due to diabetes complications, multiple sclerosis, aging, or physical injury, or damage to the parts of the brain that process color information can also lead to color blindness. In addition, exposure to certain chemicals and drugs, such as organic solvents or chloroquine, can also lead people to develop color blindness.

Who is most likely to be color blind?

Color blindness primarily affects men. About one in 12 men in the world are color blind, versus one in 200 women. The reason for this disparity between the sexes is due to the gene responsible for color blindness being located within one of the two chromosomes that determine biological sex.

The most common form of color blindness is red-green color blindness, which is most often caused by the mutated gene being passed from parent to child via the X chromosome. Since a child born female has two X chromosomes, they would need to inherit color blind mutations in both X chromosomes in order to be born color-blind; if they have the genetic mutation in only one X chromosome, the other typically compensates. On the other hand, a child born male carries only one X chromosome; if it carries the genetic mutation responsible for color blindness, there is no other X chromosome to compensate.

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How do you know if you’re color blind?

There are different tests designed to detect color blindness, its types, and its severity. These typically involve specially designed pictures made of colored dots that have numbers or shapes in a different color hidden within them. These tests are usually followed by an eye exam by a doctor.

Can color blindness be fixed?

There isn’t any treatment for color blindness. However, colored filters over eyeglasses or colored contact lenses can sometimes help color-blind people differentiate between colors more easily, depending on the type of color blindness they have.