Color Blindness Test

This screening works the same way as the classic Ishihara plates used by eye doctors since 1917. Each plate is a circle of coloured dots hiding a number. The trick is that the number differs from the background only in hue — the dot sizes and lightness are deliberately randomised — so the digit is only readable if your eyes can separate those particular red and green hues. Typical (trichromatic) colour vision reads it instantly; red-green deficient vision sees a fairly uniform field of dots.

You get 8 plates: one control plate that everyone should read, plus seven red-green plates drawn fresh on a canvas each run, with the deck shuffled and every dot placed randomly. That means no two runs look identical and the answers cannot be memorised. Type the number you see, or tap "I can't see a number", and at the end you get a verdict based on how many red-green plates you read, along with a per-plate recap of your answers.

Red-green colour vision deficiency is by far the most common type, affecting roughly 1 in 12 men and 1 in 200 women because the responsible genes sit on the X chromosome. Most people who have it live perfectly normal lives — many only discover it through a screening like this. Remember this is a fun, screen-based awareness check, not a diagnosis: monitors reproduce colour differently, so a proper assessment needs an optometrist and printed plates under controlled lighting.