The tests
Screen-based vision tests are good at one thing: spotting differences that are worth a closer look.
- The eye test uses a Tumbling E chart for each eye and gives an approximate Snellen and decimal acuity.
- The color blind test shows dot plates aimed at your red, green and blue cones.
- The astigmatism test asks whether some lines on a clock-dial chart look darker to one eye.
- The hue test asks you to find the one tile with a slightly different shade while the gap keeps shrinking.
- The contrast sensitivity test fades letters toward grey until you can no longer read them.
- The dominant eye test walks you through two classic sighting methods to find your leading eye.
Get a fair result
- Turn off night mode, blue-light filters and automatic color adjustments such as True Tone before you start.
- Set the screen to a comfortable, fairly high brightness and avoid glare from a window.
- Test each eye separately when the test asks you to, and wear your usual glasses or contact lenses unless the instructions say otherwise.
- For the eye test, calibrate the screen size first and keep the distance the test tells you.
Know the limits
A computer or phone screen is not a calibrated clinical chart, so these results are a screening, not a diagnosis. If a test suggests a problem, if your vision changes suddenly, or if you notice distorted lines, flashes or a dark curtain in your sight, see an eye doctor.