Color Blindness Test
| Type | What is hard to tell apart | Share of colorblind |
|---|---|---|
| Deuteranomaly (green-weak) | greens, oranges and light reds | the most common, ~5% of men |
| Protanomaly (red-weak) | reds appear darker than they are | ~1-2% of men |
| Tritanomaly (blue-yellow) | blues and yellows | very rare, under 0.01% |
The Ishihara plates work by hiding a number in a field of confusable colors - and the principle renders perfectly in CSS: a number drawn in one color family inside dots of a confusable family. Three plates here: a demonstration plate (12 - everyone sees it, including every type of colorblindness), then two red-green screening plates that readers with deuteranomaly often miss.
Bottom line: red-green colorblindness affects about 1 in 12 men and 1 in 200 women - if the screening plates were hard, that is the normal way to be for millions of people, not a defect to fix. The types table explains which confusable family you sit in.
The honest part: screen colors vary by device, the plates are CSS rather than calibrated ink, and this is a screening curiosity - not a diagnosis. The person to see about a real color-vision question is an optometrist, whose plates and lighting are controlled.
How to use
- Read the dot field and type the number you see - then press Next plate and repeat for all three.
- Plate 1 is the demonstration (everyone reads 12); plates 2-3 are the red-green screeners.
- Check the types table: the pair you struggled with maps to one of the three colorblindness families.
Frequently asked questions
What are the types of color blindness?
Three families: deuteranomaly (green-weak - greens, oranges and light reds blur together; the most common at roughly 5% of men), protanomaly (red-weak - reds appear darker than they are), and tritanomaly (blue-yellow, very rare at under 0.01%). Red-green in both variants affects about 1 in 12 men and 1 in 200 women, because the genes ride on the X chromosome.
Can color blindness develop later in life?
The inherited forms are stable from birth, but acquired color vision changes exist: cataracts, some medications, and optic-nerve conditions can shift color perception in adulthood - usually toward blue-yellow confusion and usually alongside other vision changes. A screening plate that suddenly reads differently than it did years ago is an optometrist conversation.
Is there a cure for color blindness?
No cure for the inherited forms, and none is urgently needed: colorblind people develop compensating strategies (brightness, position, context) that carry most of daily life. EnChroma-style tinted lenses shift some color distinctions for some wearers; the practical adaptations (color-blind-friendly palettes, labels, patterns) matter more in design.
Is this online test accurate?
It is a screening curiosity. Real Ishihara plates use calibrated ink densities under controlled lighting, and the scoring is done by a professional; screen colors vary by device, so this CSS version is the informal sibling. Its honest use: curiosity, party trick, and the first nudge toward an optometrist if the screening plates were surprisingly hard.