Ten Ishihara-style number plates, then six quick rounds spotting the odd-colored tile. Together they screen for red-green deficiency (protanopia/deuteranomaly), blue-yellow deficiency (tritanopia) and total color blindness, and give you a percent score.
Best on a well-lit screen at normal brightness, without color-filtering glasses or a blue-light/night-shift mode. This is an informal screening, not a medical diagnosis.
Color vision deficiency happens when one or more of the three types of light-sensing cone cells in the retina respond differently than usual, making certain hues harder to tell apart. Red-green forms are by far the most common — inherited on the X chromosome, they affect roughly 1 in 12 men and 1 in 200 women, ranging from a mild shift (anomalous trichromacy) to a complete inability to distinguish red from green (dichromacy). Blue-yellow deficiency is much rarer and affects men and women about equally, and total color blindness, where no hue can be distinguished at all, is rarer still.
The plates in this test are inspired by the pseudoisochromatic design Japanese ophthalmologist Dr. Shinobu Ishihara introduced in 1917: a number is picked out in dots of one color against a field of dots in another color chosen so the two are easy to separate with typical color vision but blend together for people with certain deficiencies. Real clinical screening uses printed plates under controlled, standardized lighting — a screen recreation like this one is a reasonable approximation but not a substitute for that.
Your results here are an informal screening, not a medical diagnosis: display calibration, ambient lighting, and any color-correcting glasses or filters can all shift the outcome. If your results suggest a deficiency, or you're simply curious, an eye care professional can confirm it properly. After finishing, a nickname of up to 8 alphanumeric characters saves your percentage score to the global leaderboard — higher is better.