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Deuteranomaly

In deuteranomaly the green-sensitive (M) cones are present but their sensitivity is shifted towards the red-sensitive cones. Red and green signals become more similar, so some reds, greens, browns and oranges are harder to tell apart. It ranges from barely noticeable to fairly strong.

Deuteranomaly is the milder, more common form of deutan color blindness (sometimes called green-weak color vision). The complete form is deuteranopia.

Red-green color vision deficiency · Last updated 2026-11-10

What does deuteranomaly look like?

Illustration of fruit in a blue bowl with typical color vision: red apple, green apple, yellow lemon, orange, purple grapes, pink peach and blueberries.Typical color vision
The same fruit bowl simulated with moderate deuteranomaly. Reds, oranges, yellows and greens move closer together, and pink and purple lose some of their red. Blue and yellow stay clear.Simulated moderate deuteranomaly
Reds, oranges, yellows and greens move closer together, and pink and purple lose some of their red. Blue and yellow stay clear.
Nine color swatches (red, orange, yellow, green, teal, blue, purple, pink and brown) with typical vision and simulated with moderate deuteranomaly.
Common colors with typical vision (top) and simulated moderate deuteranomaly (bottom). Images are simulations based on the Machado, Oliveira & Fernandes (2009) model at moderate severity; real experience varies from person to person and with your screen.
  • Greens, yellows, oranges and reds can look more alike, especially in dim light or small areas.
  • Muted colors are harder than bright, saturated ones.
  • Many people with mild deuteranomaly don’t know they have it until they take a test.

Try our color blind simulator to see your own photos the way someone with a deutan deficiency might.

How common is deuteranomaly?

About 5% of men and roughly 0.4% of women of Northern European ancestry, making it the most common color vision deficiency.

Everyday situations that can be tricky

  • Telling ripe from unripe fruit, or rare from cooked meat.
  • Reading charts, maps and status lights that rely on red versus green.
  • Matching clothes (e.g. brown versus green, purple versus blue).

Causes

It is almost always inherited through the X chromosome (variants in the OPN1MW/OPN1LW gene array), which is why it is far more common in men. It is present from birth and does not get worse over time.

Deuteranomaly vs deuteranopia

Both are deutan types: they involve the green-sensitive (M) cones. In deuteranomaly those cones are present but shifted toward the red-sensitive cones, so some red-green discrimination remains and severity ranges from mild to strong. In deuteranopia the green-sensitive cones are missing or not working, so colors along the red-green axis collapse much more. A plate test can suggest which is more likely; eye care professionals use an anomaloscope to tell them apart.

Read more about deuteranopia.

Glasses, apps and other aids

Color-enhancing glasses with notch filters can increase the contrast between reds and greens for some people with deuteranomaly. They do not restore normal color vision and results vary from person to person. What the studies found, type by type: do color blind glasses work?

Phone and computer accessibility settings (color filters), color-identifier apps, and asking for labels or patterns on color-coded information can all help. There is currently no approved cure for inherited color blindness.

How is deuteranomaly diagnosed?

Eye care professionals use plate tests (such as Ishihara or HRR plates), arrangement tests and, for a precise diagnosis, an anomaloscope. Online tests like ours can flag a likely deficiency but can’t replace a clinical test.

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Deuteranomaly FAQ

What is deutan color blindness?

Deutan color blindness is the group of red-green color vision deficiencies that involve the green-sensitive (M) cones. It includes deuteranomaly (green cones shifted) and deuteranopia (green cones missing or not working). Together they are the most common inherited type of color blindness.

What does deuteranomaly look like?

Greens, yellows, oranges and reds look more alike, and muted or dark shades are harder to separate than bright ones. How strong the effect is depends on the person; the images above simulate a moderate case.

Is mild deuteranomaly a problem?

Many people with mild deuteranomaly go through daily life without noticing it. It can still matter for color-coded information and for jobs with a color vision standard, so it is worth knowing about. Only an eye care professional can confirm the type and severity.

Can deuteranomaly get worse or be cured?

Inherited deuteranomaly is present from birth and normally stays the same throughout life. There is currently no approved cure. A change in color vision later in life is different and should be checked by an eye doctor.

Do color blind glasses work for deuteranomaly?

Some people with deuteranomaly report better red-green contrast with notch-filter glasses. They do not restore normal color vision, results vary from person to person, and they are not a way to pass a color vision test.

Can women have deuteranomaly?

Yes, but it is much less common. The genes involved are on the X chromosome, so a woman usually needs the variant on both X chromosomes to be affected, while a man needs only one.

Other types of color blindness

Deuteranomaly is one of four types of red-green color blindness. See all types of color blindness compared side by side, or what colorblind people see with each type.

Sources

  1. National Eye Institute. Types of color vision deficiency. nei.nih.gov
  2. MedlinePlus Genetics, U.S. National Library of Medicine. Color vision deficiency. medlineplus.gov
  3. Birch J. Worldwide prevalence of red-green color deficiency. JOSA A. 2012;29(3):313–320. doi.org
  4. Nathans J, Piantanida TP, Eddy RL, Shows TB, Hogness DS. Molecular genetics of inherited variation in human color vision. Science. 1986;232(4747):203–210. pubmed.ncbi.nlm.nih.gov
  5. Simunovic MP. Colour vision deficiency. Eye. 2010;24(5):747–755. pubmed.ncbi.nlm.nih.gov
  6. Machado GM, Oliveira MM, Fernandes LAF. A physiologically-based model for simulation of color vision deficiency. IEEE TVCG. 2009;15(6):1291–1298. (Used for the simulated images.) doi.org

Note: this is a screening, not a diagnosis. Online tests can’t control your screen’s colors or brightness, so confirm any result with an eye care professional. Medical disclaimer · How the test works

Could color-enhancing glasses help?

Glasses with special notch filters can boost the contrast between reds and greens for some people with mild to moderate red-green color vision deficiency (protanomaly or deuteranomaly). They don’t cure color blindness and they work less well for strong types, so look for a trial period or return policy.

Do color blind glasses work?

More color vision tests

Color blind testFull screening: red-green and blue-yellow, with type and severity.Red-green color blind testDeeper check for protan and deutan types.Tritanopia testBlue-yellow (tritan) color vision screening.Color blind test for kidsShapes instead of numbers, for children who can’t read digits yet.Reverse color blind testHidden-figure plates that color blind people can see more easily.Color blind simulatorSee any photo the way people with color blindness see it.