Deuteranomaly Test (Green-Weak)
This Ishihara-style test screens for deuteranomaly, the most common color vision deficiency worldwide. Deuteranomaly occurs when the green-sensitive (M) cones have a shifted spectral response, reducing the ability to distinguish between reds, greens, and similar hues.
Plate 1 of 10
What number do you see in the circle above?
Test Instructions
- Look at each colored circle
- Enter the number you see (if any)
- Take your time — there's no rush
- Make sure your screen brightness is normal
- Ensure good lighting conditions
Medical Disclaimer: This online test is a screening tool. While it can help identify potential color vision deficiencies, it is not a substitute for professional medical diagnosis. Screen brightness, lighting conditions, and display calibration can affect results.
What This Test Screens For
Deuteranomaly affects approximately 5% of men and 0.35% of women, making it by far the most common color vision deficiency. The M-cones are present but their opsin protein is shifted toward longer wavelengths, overlapping more with L-cones. This compresses the range of distinguishable colors in the red-green axis while maintaining three functional cone types (anomalous trichromacy).
Limitations of This Test
This screening detects red-green deficiency but cannot identify deuteranomaly specifically. Distinguishing deuteranomaly from deuteranopia, protanomaly, or protanopia requires anomaloscope testing. People with very mild deuteranomaly may pass this screening despite having a measurable color vision difference detectable by more sensitive instruments.
What to Expect
You will see 10 circular plates with hidden numbers. Because deuteranomaly severity varies widely, your score may range from near-normal (mild cases) to significantly impaired (severe cases approaching deuteranopia). The test takes 2-3 minutes.
Why Is Deuteranomaly So Common?
The green opsin gene (OPN1MW) sits adjacent to the red opsin gene (OPN1LW) on the X chromosome in a tandem arrangement. During cell division, unequal recombination between these similar genes frequently produces hybrid genes with spectral properties between normal red and green opsins. This genetic instability is why deuteranomaly is orders of magnitude more common than other color vision deficiencies.
Living with Deuteranomaly
Many people with deuteranomaly discover their condition only through screening tests, having adapted unconsciously throughout childhood. The practical impact ranges from negligible (mild cases) to moderate difficulty with color-coded information. Digital accessibility features, color-filtering glasses, and color identification apps can all help. Some researchers suggest anomalous trichromats may have advantages in detecting camouflaged objects.
Frequently Asked Questions
Can someone with deuteranomaly see any green?
Yes. Unlike deuteranopia, where M-cones are absent, deuteranomaly involves M-cones that work but are tuned to a slightly different wavelength. People with deuteranomaly perceive green, just with reduced discrimination between green and neighboring hues like yellow, brown, and red.
Will color-filtering glasses cure deuteranomaly?
Color-filtering glasses do not cure deuteranomaly, but they can significantly enhance color discrimination while worn. They work by filtering the wavelengths where M-cone and L-cone sensitivities overlap. Many users report seeing more vivid, distinct colors. The effect is only present while wearing the glasses.
Is 5% of men really affected?
Yes. In a classroom of 30 male students, on average one or two will have some degree of deuteranomaly. The prevalence varies somewhat among ethnic groups but remains the most common color vision deficiency worldwide.
Learn more about this condition
Related Tests
Deuteranopia Test (Green-Blind)
This Ishihara-style test screens for deuteranopia, the complete absence of green-sensitive (M) cones. People with deuteranopia cannot distinguish the hidden numbers because the plate colors lie along the red-green confusion axis that their vision cannot resolve.
Protanomaly Test (Red-Weak)
This Ishihara-style test screens for protanomaly, a mild form of red-green color blindness where the red-sensitive (L) cones are present but spectrally shifted. People with protanomaly may have difficulty with some or all of these plates depending on the severity of their condition.
Red-Green Colorblind Test
This Ishihara-style test screens for all types of red-green color blindness, including protanopia, deuteranopia, protanomaly, and deuteranomaly. Red-green color deficiency is the most common form of color blindness, affecting approximately 8% of men and 0.4% of women worldwide.