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Detect Color Blindness
Blue-Yellow Dichromacy (strong)

Tritanopia

By The Detect Color Blindness editorial team Last reviewed

Absent blue cones; blue-yellow confusion. Rare.

What Tritanopia means

Tritanopia means the blue-sensitive (S) cones are missing. The blue-yellow axis of colour vision is lost: blues look greener, yellows fade toward light grey or pink, and the world takes on a red-teal cast. It is one of the rarest forms of colour blindness.

What it can look like day to day

  • Blue looks green; yellow looks grey or pink
  • Sky and sea can appear similar
  • Distinguishing purple from red is hard
  • Colour-coded transit maps are confusing

How common is it?

Very rare (< 0.01%). Colour vision deficiency overall affects roughly 1 in 12 men and 1 in 200 women, see the full prevalence breakdown.

Can glasses help?

Most colour-blind glasses target red-green deficiency, so they generally do not help tritanopia. See do colour blind glasses work?

How to test for Tritanopia

Start with the free online color blind test or the blue-yellow test. For a diagnosis, an eye-care professional uses calibrated plates, an anomaloscope or an arrangement test. Want to see the difference? Try the colour blindness simulator.

Take the color blind test See it in the simulator

Other types of colour blindness

Deuteranomaly Reduced sensitivity to green light, the most common form. Read more → Deuteranopia Absent green cones, a stronger red-green deficiency. Read more → Protanomaly Reduced sensitivity to red light; reds look dimmer. Read more → Protanopia Absent red cones; a strong red-green deficiency. Read more → Tritanomaly Reduced sensitivity to blue light; rare. Read more → Achromatopsia (Monochromacy) Little or no colour vision, seeing mostly in shades. Read more →

Frequently asked questions

Is this result a diagnosis?
No. It's an educational screening result based on an online plate test, which can be affected by your screen and lighting. Only an eye-care professional can diagnose colour vision deficiency.
Can color blindness get worse over time?
Inherited colour blindness is stable and does not progress. If your colour vision changes noticeably over time, that can signal an eye or health condition and should be checked by a professional.
Can color blindness be cured?
Inherited colour blindness can't currently be cured. Special filter glasses help some people with red-green types by boosting contrast, and everyday tools and habits make colour tasks easier.

Keep exploring

What next?

Take the color blind test 14 quick plates · instant type & severity · no sign-up. Start the test → See how you see colour Simulate protan, deutan, tritan & more on any image. Open the simulator → Do colour blind glasses work? Honest comparison of EnChroma, Pilestone & ColorLite. Read the guide →