Health Library

Shades of Gray? The Facts of Color-blindness

IMAGE Color-blindness is a common condition that is mainly found in men. It is also somewhat of a misnomer. Color-blindness usually does not make someone blind to all colors. It is more of a color vision defiency. People with the deficiency see colors, but less colors than others without color-blindness.

In most cases, color-blindness is an inherited disorder that is passed from mother to son. Others acquire color-blindness from a health condition or medications that cause damage to the retina of the eye. The retina is the back part of the eye where there are 2 types of cells that are light sensitive. The light sensitive cells are called rods and cones. The cone cells are able to detect 3 colors: red, green, and blue. The type of color-blindness you have depends on how many of and how well the 3 cone cells work.

Types of Color-blindness

IMAGE There are several types of color blindness. In each type, the cones work a little differently. Here is an overview of each type.


People with normal color vision use all 3 types of cone cells, which help differentiate colors and shades of colors. This is called trichromacy. There are variations of trichromacy, which affect color vision.

With anamalous trichromacy, all 3 cone cells work, but 1 is slightly off. This creates a wide range of color perception depending on which cone is faulty:

  • Protanomaly—reduced ability to see red
  • Deuteranomaly—the most common type, with reduced ability to see green
  • Tritanomaly—extremely rare, with reduced ability to see blue

People who have reduced ability to see reds and greens are known as red-green color-blind. They have trouble seeing differences with reds, greens, browns, oranges, yellows, and grays. They also have a tendency to confuse blues and purples.


Dichromats have 2 types of cones that see color and 1 that does not. Dichromacy includes:

  • Protanopia—inability to see red, with confusion among dark shades, such as dark red and black
  • Deuteranopia—inability to see green, with confusion among medium shades of red that have similar tones to greens or oranges
  • Tritanopia—inability to see blue

People who are color-blind to reds or greens see most colors as muddy green, blue, or yellow.


Monochromacy is rare. People with monochromacy only see shades of gray with no color at all, much like an old black and white movie.

Living with Color-blindess

Color-blindness is not routinely tested. A child may be tested if they are having trouble telling shades of color apart, or is doing poorly in school. For those that have inherited forms, there are no effective treatments. Some people use tinted glasses, but others find them more difficult to use. Acquired color-blindness sometimes can be treated with a change in medications, stopping medications, or treating the condition causing the deficiency.

For now, the best that someone with color-blindness can do is manage to live with it. It is true to a certain extent that someone who cannot see color does not know what they miss, but in a world of color, not seeing it makes navigating life difficult. Take a minute to look around you and imagine what it would be like to see shades of the same color or no color at all.

It affects many aspects of daily life. It may keep someone from a job they want, like a chef, pilot, graphics designer, or doctor. With those who have jobs, it can create problems in the workplace. For example, color documents with graphs may create confusion or misunderstanding. New employees may struggle to hide their deficiency until they feel comfortable enough to fit in for fear of being fired. Others may have trouble with traffic lights with its reds and greens, while others may struggle differentiating signal lights on cars.

Everyday diversions, like art or gardening, may hold no interest to someone who cannot detect color differences. And then there is the daily task of getting dressed or putting on make-up.

For now, more research is needed to determine if treatments need to be developed or if living with color-blindness is the only option.


American Academy of Ophthalmology

Kids Health—Nemours Foundation

Canadian Resources

About Kids Health—The Hospital for Sick Children

The College of Family Physicians of Canada


Colour blindness. Colour Blindness Awareness website. Available at: Accessed June 8, 2017.

Types of colour blindness. Colour Blindness Awareness website. Available at: Accessed June 8, 2017.

What is color blindness? American Academy of Ophthalmology website. Available at: Accessed June 8, 2017.