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.
Before you begin
Set up your screen and lighting
Display conditions can materially change an online color vision result. Take a moment to check these items before starting.
- Use a color screen at its normal brightness, viewed straight on.
- Turn off Night Shift, blue-light filters, grayscale, and color filters.
- Use neutral room lighting and avoid glare on the display.
- Wear your usual prescription glasses or contacts, if applicable.
- Use your first impression and answer each plate within about 5 seconds.
What This Test Screens For
Deuteranopia is the most common form of dichromatic color vision deficiency. The M-cones (medium-wavelength, green-sensitive) are entirely absent, leaving the visual system to interpret color using only L-cones and S-cones. This produces confusion between reds and greens similar to protanopia, but without the brightness reduction in the red end of the spectrum.
Limitations of This Test
Ishihara-style plates cannot differentiate deuteranopia from protanopia or the anomalous forms (deuteranomaly, protanomaly). All red-green deficiencies fail these plates in similar ways. Precise classification requires anomaloscope testing. Monitor settings and room lighting affect accuracy.
What to Expect
You will see 10 circular plates filled with colored dots. Each plate hides a number visible to people with normal color vision. Enter the number you see or indicate you see nothing. The test takes 2-3 minutes.
How Does This Deuteranopia Test Work?
The plates present numbers rendered in colors that differ from the background only along the red-green confusion axis. People with normal trichromatic vision easily distinguish the hue difference. People with deuteranopia, who lack M-cones, cannot resolve this difference and the number becomes invisible against the similarly-valued background dots.
Understanding Deuteranopia
Deuteranopia affects approximately 1.2% of men and 0.01% of women. It is caused by mutations or deletions in the OPN1MW gene on the X chromosome. The condition produces red-green confusion similar to protanopia but does not cause the characteristic darkening of reds. Colors are perceived primarily as blues and golds, with the red-green range compressed into similar-looking tones.
Frequently Asked Questions
What is the difference between deuteranopia and deuteranomaly?
Deuteranopia is the complete absence of green-sensitive M-cones, resulting in dichromatic vision. Deuteranomaly is the milder form where M-cones are present but spectrally shifted, resulting in anomalous trichromatic vision. Deuteranomaly is far more common (5% of men vs 1.2%) and generally causes less severe color confusion.
Is deuteranopia more common than protanopia?
Yes. Deuteranopia affects about 1.2% of men versus 1% for protanopia. When including the anomalous forms, deutan deficiencies (deuteranopia + deuteranomaly) are collectively much more common than protan deficiencies because the green opsin gene is more susceptible to deletion through unequal recombination.
Can color-filtering glasses help with deuteranopia?
Color-filtering glasses work by increasing spectral separation between cone signals. They tend to be less effective for deuteranopia (where M-cones are entirely absent) than for deuteranomaly (where shifted M-cones can still respond to enhanced contrast). Individual results vary, and a trial is recommended.
Learn more about this condition
Related Tests
Protanopia Test (Red-Blind)
This Ishihara-style test screens for protanopia, the complete absence of red-sensitive (L) cones. If you have protanopia, you will have difficulty seeing the numbers hidden in these plates because the foreground and background colors fall along the red-green confusion axis.
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.
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.