Color blindness, or color vision deficiency, causes a person to see colors differently from most other people. There are several types of color blindness.
Color vision deficiency or loss has multiple possible causes, including genetic factors and eye damage.
Many people with color vision deficiency have difficulty distinguishing between green and red, and this can affect their perception of other colors as well. In rare cases, someone may not be able to see colors at all.
Here, learn more about the different types of color blindness.
Color vision deficiency, previously known as color blindness, is a condition in which a person cannot see the full range of colors.
The type of color vision deficiency a person has will depend on the affected part of the eye. Cones are photoreceptor cells
In other words, cone cells enable people to see colors.
There are three types of cones:
- L-cones transmit red light. L-cone damage or loss causes protanomaly or protanopia.
- M-cones transmit green light. M-cone damage or loss leads to deuteranomaly or deuteranopia.
- S-cones transmit blue light. S-cone damage or loss results in tritanomaly or tritanopia.
Mild color vision deficiency involves damage (“-omaly”) to one or more cones. A severe deficiency (“-opia”) occurs when one or more cone types are missing. In the case of a severe deficiency, a person will not see certain colors at all.
Red-green
This may cause them to confuse various colors since red and green contribute to many other colors, including purple and orange.
| Type | Color affected | Confusion between |
|---|---|---|
| protanomaly or protanopia | red light | • black and various reds • dark brown and dark green, dark orange, dark red, dark blue, dark purple, or black • some blues and some reds, purples, and dark pinks • mid-greens and some shades of orange |
| deuteranomaly or deuteranopia | green light | • mid-reds and mid-greens • mid-reds and mid-browns • blue-greens and gray • blue-greens and pink • bright greens and yellow • pale pinks and light gray or white • light blues and lilac |
People with protanomaly or deuteranomaly
Blue-yellow
Some people have difficulty perceiving blues and yellows. The mild form is tritanomaly, and the more severe form is tritanopia.
A person with either of these conditions may have difficulty distinguishing between:
- light blues and grays
- black and dark purples
- mid-greens and blues
- oranges and reds
People with tritanopia
- blue and green
- purple and red
- yellow and pink
H3 complete loss of color vision
In very rare cases, a person cannot see any colors. Monochromacy (achromatopsia) occurs when none of the cones that enable color vision work. The person sees the world in black, white, and gray, similarly to an old black-and-white movie.
- very low vision, usually 20/200 or worse
- extreme sensitivity to light
- nystagmus (involuntary eye movements)
Color vision deficiency
The following factors and conditions
- glaucoma
- age-related macular degeneration
- cataracts
- Alzheimer’s disease
- multiple sclerosis
- the use of medications such as hydroxychloroquine (Plaquenil)
- eye injuries, such as retinal detachment
- a brain tumor
- radiation or laser treatment
- damage to the optic nerve, the optic tract, and parts of the brain that enable vision
Color vision deficiency
- distinguish between colors
- perceive shades of a color
- see whether a color is bright or dull
The colors that cause confusion will depend on the type of color vision deficiency a person has.
A person may not be aware that they have color vision deficiency, especially if it is mild. However, it can become clear in some situations, such as when a child starts school and confuses colors in artwork and on reading tests.
If any color vision loss occurs suddenly or if a person experiences symptoms such as headache, flashing lights, or other vision changes, it is best to consult a doctor. These may be signs of a more serious underlying condition.
Doctors often use visual tests known as Ishihara plates to test for color vision deficiency.
The plates present a random pattern of colored dots with a specifically colored path or number embedded in it. If a person cannot see the figure among the dots, they may have color vision deficiency. However, this test may not accurately diagnose the type or severity.
Doctors
An ophthalmologist or optometrist may recommend genetic tests and tests to assess for damage to the retina or other changes.
People with color vision deficiency may experience challenges in many areas of life, such as:
- understanding color-coded functions on labels and electronic equipment
- following instructions or participating in activities in which color is a factor
- choosing clothing or cosmetics
- doing certain jobs, such as graphic design
Color vision deficiency
However, a range of accommodations can help, such as:
- wearing special glasses or lenses, in some cases
- using visual aids that label colors onscreen, such as Color Blind Pal
- treating underlying medical conditions
- asking a friend to help with clothes shopping or labeling items in the home
- seeking counseling if color vision problems affect mental health
Most people with color vision deficiency have difficulty distinguishing between red and green. Among the red-green types, the most common is deuteranomaly, a mild type that makes some shades of green look more red.
A person with monochromatic color blindness does not see any colors — they see only black, white, and gray. With dichromatic color blindness, a person sees two colors out of red, green, and blue but not the third.
Most people are trichromatic, which means they see all colors. Anomolous trichromacy occurs when a person sees all three colors but may have some difficulty seeing one or more.
Gray can appear green if a person has tritanomaly or tritanopia, which affects how they see blue and yellow.
The three main types of color blindness are red-green, blue-yellow, and monochromatic. Cones are a part of the eye that enables people to see colors. The extent and type of deficiency depend on which cone cells are missing or damaged in a person’s eye.
Most people with color vision deficiency have a mild form that causes some confusion between red and green. Total color vision deficiency, in which people see only black and white, is rare.