Achromatopsia Test (Complete Color Blindness)
This comprehensive test combines both red-green (Ishihara-style) and blue-yellow (tritan-style) plates to screen for achromatopsia, a rare condition in which all cone photoreceptors are nonfunctional. A person with achromatopsia will have difficulty with both plate types.
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
Achromatopsia (rod monochromacy) is a rare condition in which all three cone types are absent or nonfunctional, leaving the person with rod-only vision. Because no cones function, a person with achromatopsia cannot distinguish colors on either the red-green or blue-yellow axis. This test presents both plate types as a combined screen.
Limitations of This Test
Achromatopsia is a complex condition with symptoms beyond color confusion, including severe photophobia, nystagmus, and reduced visual acuity (typically 20/200). An online color plate test cannot evaluate these additional symptoms. Failing both plate types could also indicate a combination of separate red-green and blue-yellow deficiencies rather than achromatopsia. Clinical diagnosis requires electroretinography (ERG) and genetic testing.
What to Expect
You will see 10 plates total: 5 Ishihara-style plates (red-green axis) followed by 5 tritan-style plates (blue-yellow axis). Enter the number you see in each plate or indicate you see nothing. A person with achromatopsia would typically fail both sections. The test takes 3-4 minutes.
Why Two Types of Plates?
Most color vision deficiencies affect only one axis of color discrimination. Red-green deficiency (protan/deutan) leaves blue-yellow discrimination intact, and tritan deficiency leaves red-green discrimination intact. Achromatopsia is unique because all cone types are affected, meaning color confusion occurs across the entire spectrum. By testing both axes, this screening can flag the possibility of complete cone dysfunction.
Understanding Achromatopsia
Achromatopsia is a rare autosomal recessive condition affecting approximately 1 in 30,000 people. It is caused by mutations in genes essential for cone phototransduction (most commonly CNGB3 and CNGA3). Vision relies entirely on rod cells, resulting in a complete absence of color perception, extreme light sensitivity, and visual acuity around 20/200. It is the only form of color blindness in which the individual truly sees in grayscale.
Frequently Asked Questions
Will failing this test confirm I have achromatopsia?
No. Failing both red-green and blue-yellow plates indicates a broad color vision deficiency, but achromatopsia involves additional symptoms like severe photophobia, nystagmus, and very poor visual acuity that this test cannot evaluate. A definitive diagnosis requires an electroretinogram (ERG) and genetic testing from a specialist.
How rare is achromatopsia?
Achromatopsia affects approximately 1 in 30,000 people worldwide. It is inherited as an autosomal recessive trait, meaning both parents must carry a mutation. The condition affects men and women equally.
Is achromatopsia the same as the common types of color blindness?
No. Common color blindness (protanopia, deuteranopia, etc.) involves the loss of one cone type, leaving the other two functional. People with common color blindness can still perceive many colors. Achromatopsia involves the loss of all cone function, resulting in grayscale vision plus photophobia and reduced acuity.
Learn more about this condition
Related Tests
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.
Blue-Yellow Colorblind Test
This test uses specialized blue-yellow pseudoisochromatic plates to screen for tritan-type color vision deficiency, including tritanopia and tritanomaly. Standard Ishihara tests cannot detect these conditions because they only test the red-green axis.
Tritanopia Test (Blue-Yellow Blind)
This test uses blue-yellow pseudoisochromatic plates specifically designed to screen for tritanopia and tritan-type color vision deficiency. Unlike standard Ishihara tests, which only detect red-green deficiency, these plates use colors along the tritan confusion axis.