Protan Test (Red-Weak)
A focused screening for protanomaly, the red-weak type of color vision deficiency, where reds also look darker than usual. Read the number in each plate; we'll estimate whether your red-axis discrimination looks typical.
You'll see 10 plates of colored dots. For each one, tap the number you see, or "I can't see a number." Go with your first impression; each plate has a short timer.
Some plates show no number to most people, and “I can't see a number” is a normal, expected answer, not a failure.
Best on a phone or laptop at full screen brightness. Keyboard: press a number key, or Enter if you can't see one.
What protan vision is like
Protan color vision deficiency comes from the red-sensitive cones. Because those cones also carry much of our sense of brightness for warm colors, protan vision has a distinctive trait the other types don't: reds appear darker, not just less saturated.
Common everyday effects:
- Red and green traffic or brake lights being harder to judge
- Reds looking brownish, dark, or nearly black
- Difficulty telling red, orange, and green apart in low light
Like deutan deficiency, protan is inherited on the X chromosome and is much more common in men. Visual sharpness is normal; it's the red-green discrimination and red brightness that are affected.
Frequently asked
What is protanomaly?
Protanomaly is a red-weak color vision deficiency. The red-sensitive (L) cones are shifted, so reds look duller and darker and can be confused with greens and browns. In the stronger form, protanopia, the red cones are effectively missing.
Why do protans see red as darker?
The red-sensitive cones also contribute a lot to how bright we perceive warm colors. When they're weak or absent, reds lose brightness, so a red traffic light or brake light can look dimmer and be easier to miss.
Is a protan test a medical diagnosis?
No. It's a screening tool that runs entirely in your browser, and screen brightness and calibration affect the result. For a clinical assessment, see an optometrist or ophthalmologist.