Tritanomaly Test (Blue-Weak)
This test uses blue-yellow pseudoisochromatic plates to screen for tritanomaly, an extremely rare condition where the blue-sensitive (S) cones have altered spectral sensitivity. Standard Ishihara tests cannot detect tritan-type deficiency.
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
Tritanomaly is the mildest and rarest of the common color vision deficiency types. The S-cones are present but have shifted spectral sensitivity, reducing blue-yellow discrimination. Because all three cone types still function, tritanomaly produces anomalous trichromatic vision with subtle color confusion along the blue-yellow axis.
Limitations of This Test
This test cannot distinguish tritanomaly from tritanopia. Because inherited tritanomaly is extremely rare (approximately 0.001% of the population), a positive result is more likely to indicate acquired tritan deficiency from eye disease or aging. A comprehensive eye exam is recommended alongside any positive tritan screening. Monitor color accuracy significantly affects results.
What to Expect
You will see 10 circular plates with numbers rendered in blue-purple tones against yellow-gold backgrounds. People with tritanomaly may miss some plates depending on severity. The test takes 2-3 minutes.
Inherited vs. Acquired Tritanomaly
Inherited tritanomaly is one of the rarest color vision deficiencies, affecting approximately 0.001% of people. However, acquired tritan-type deficiency is much more common and can develop from cataracts (lens yellowing), glaucoma, macular degeneration, diabetic retinopathy, or certain medications. If you fail this test, a comprehensive eye exam is recommended to determine whether the cause is inherited or acquired.
How Tritanomaly Affects Color Perception
Blues may appear slightly greener or more washed out than normal, and yellows may look slightly pinkish or orangish. The effect is generally subtle, and many people with mild tritanomaly are unaware of any color perception difference. Because S-cones contribute relatively little to overall brightness perception, tritanomaly does not cause noticeable changes in perceived brightness.
Frequently Asked Questions
How rare is tritanomaly?
Inherited tritanomaly affects approximately 0.001% of the population, making it roughly 5,000 times less common than deuteranomaly. Most tritan-type color vision deficiency encountered in practice is acquired from aging or eye disease rather than inherited.
Why does this test use different plates than the standard colorblind test?
Standard Ishihara plates test the red-green axis and cannot detect tritan-type deficiency at all. People with tritanomaly will pass an Ishihara test with a normal score. This test uses plates designed along the blue-yellow confusion axis, which is the axis affected in tritan deficiency.
Learn more about this condition
Related Tests
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.
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.
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.