Astigmatism Test with a Clock Dial Chart
This astigmatism test screens each eye for blur using a clock dial chart — 12 lines radiating from a center dot at 30-degree intervals. If some lines look darker, thicker, or sharper than the rest, your eye may be focusing light unevenly, which is the hallmark of astigmatism.
Astigmatism is a common refractive error caused by an irregularly shaped cornea or lens — the eye is curved more like a football than a basketball, so light focuses unevenly on the retina. This tool is for anyone who notices blurry or distorted vision and wants a quick at-home check before booking an eye exam.
How to Use the Astigmatism Test
Before you begin, sit about arm's length (35–40 cm / 14–16 inches) from your screen in a well-lit room with normal brightness and no glare. If you wear glasses or contact lenses, keep them on so the test reflects your corrected vision.
Start the test
Read the setup instructions, then tap Start Test to open the clock dial chart.
Test your right eye
Cover your left eye gently with your hand — don't press on it — and look at the center dot of the chart.
Mark the lines
If every line looks equally dark and sharp, tap All lines look equal. If some lines stand out, click those lines to select them, then tap Confirm & Next. Use Clear to start the selection over.
Test your left eye
Cover your right eye and repeat the same process on the left eye.
Read your results
See a separate result for each eye — a normal status when all lines looked equal, or a possible-astigmatism status with an estimated axis when you marked some lines.
Features
Clock Dial Chart
A crisp SVG chart with 12 radiating lines spaced 30° apart (0° to 330°), each labeled with its degree and anchored to a center dot.
Guided 4-Step Flow
A clear path from Setup to Right Eye, Left Eye, and Results, with a step indicator that marks your active and completed stages.
Interactive Line Selection
Click or tap any line that looks darker or sharper to highlight it. Select several lines, deselect by tapping again, or clear them all at once.
Per-Eye Results
Each eye gets its own result card with a normal or possible-astigmatism status, since each eye can differ in amount and axis.
Estimated Axis
When lines are marked, the tool estimates the astigmatism axis from the circular mean of the selected angles, offset by 90°.
Mini Chart in Results
Every result card shows a small dial highlighting which lines you selected, so you can see exactly what fed the estimate.
Cover-Eye Guidance
Each step tells you which eye to cover and reminds you to look at the center dot, so you test one eye at a time the way professionals do.
Mobile-Friendly Tapping
Enlarged invisible hit areas around each line make selection easy on touchscreens without misclicks.
Frequently Asked Questions
How does an online astigmatism test work?
You look at a clock dial chart — 12 lines spaced 30° apart around a center dot — one eye at a time. An eye with astigmatism focuses light differently along different axes, so some lines appear darker or sharper. You mark the lines that stand out, and the tool estimates an axis from your selections.
How accurate is an at-home astigmatism test?
It's an indication, not a diagnosis. A comprehensive eye exam measures cylinder power and axis precisely, while an at-home test is affected by screen quality, viewing distance, and lighting. If the test suggests possible astigmatism, book an appointment with an optometrist or ophthalmologist.
What does the "estimated axis" mean?
The axis is a number between 0° and 180° that indicates the orientation of astigmatism in your eye — the meridian where correction would be needed. Eye care professionals pair this axis with cylinder power to prescribe corrective lenses.
Should I wear my glasses during the test?
Yes. If you wear glasses or contacts, keep them on so the test reflects your corrected vision. If all lines look equal with your correction, your current prescription is handling any astigmatism well. If lines still look unequal, your prescription may need updating.
Why do I test one eye at a time?
Each eye can have a different amount and axis of astigmatism. Testing one eye at a time gives you separate results for each eye, which is how eye care professionals examine vision too.
What should I do if the test shows possible astigmatism?
Don't be alarmed — mild astigmatism is extremely common and often needs no treatment. But if you have blurry vision, eye strain, or headaches, schedule an eye exam so a professional can measure the exact degree and decide whether corrective lenses are needed.
Is my data saved or sent anywhere?
No. All processing happens entirely in your browser, and no test data is uploaded to any server. Retake the test as often as you like.
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