How to use
- Turn off night light, blue light filters and color modes such as "vivid" or "reading", and set the brightness to a normal level.
- Sit at a normal distance and look at each plate for no more than a few seconds.
- Type the number you see and confirm, or press "I can't see a number".
- The plates get harder step by step. The result shows how many plates of each type you read correctly.
Frequently asked questions
Is this a medical diagnosis?
No. Screens differ in color and brightness, so this test can only give a hint. For a diagnosis, see an eye doctor; they use printed plates under standard light and anomaloscope tests.
How are the plates made?
Each plate is generated in your browser. The colors of the number and the background differ only in what one type of cone cell sees, and random brightness changes hide all other clues. That is why a person missing that cone type cannot find the number.
I missed only the hardest plates. Is that normal?
Often, yes. The faintest plates are close to the limit of normal vision and depend on your screen. Missing most plates of one type is a clearer sign than missing the last one.