In short: the clock dial (or sunburst) chart has lines pointing in every direction. With one eye covered, if some lines look darker or sharper than others, that can happen with astigmatism, a common and easily corrected focusing difference. This page shows the dial and asks two questions per eye; an optometrist can measure astigmatism precisely in a normal eye exam.
Twelve directions
Lines every 15 degrees, like the hours of a clock and the spaces between them.
One question per eye
All lines the same, or some darker; if so, which direction.
A short summary
For each eye, with the direction you noticed.
How the test works
- Decide about glasses. Take them off to see whether you notice a difference, or keep them on to see whether they correct it.
- Hold the screen at arm’s length and look at the centre of the dial.
- Cover one eye. Do all the lines look equally dark and sharp?
- If not, pick the darkest direction using the hours of a clock face, then switch eyes.
What affects the result
Screen sharpness, brightness, tired eyes and looking away from the centre can all make some lines look different for a moment. Look at the centre, blink normally and give it a few seconds before answering.
What this test is not
It does not measure your prescription or the strength of any astigmatism, and it does not check eye health. A normal result does not replace an eye exam.
Frequently asked questions
What is astigmatism?
A focusing difference where the eye bends light more in one direction than another, so some lines look sharper than others. It is very common and usually corrected with glasses or contact lenses.
Can I test astigmatism at home?
You can notice signs of it with a dial like this one. Only an eye exam measures it and decides whether you need correction.
Should I do the test with glasses?
Try both: without glasses to see whether you notice darker lines, and with them to see whether your current glasses correct it.
Is my result saved?
The test runs on your device and keeps the result only while this page is open; nothing is stored in your browser. You can copy it, or save it in a free Anpheros account.
