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APP-007
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Astigmatism · in your browser

The other number on your prescription.
Let's actually measure it.

Astigmatism is two perpendicular meridians of the eye with different refractive powers. Each one has its own far point. The cm method works per meridian when the target is a grating — rotate it six ways, the dropout distance at each rotation is that meridian's number. Sphere, cylinder, and axis come out at the end.

We'll watch your eyes through your camera. Nothing leaves this browser — no frames are uploaded or saved.

Sturm's conoidCone of light from an astigmatic eye narrows to a vertical line focus, expands through a circle of least confusion, then converges to a perpendicular horizontal line focus.pupilfocal line 1horizontal meridiancircle of least confusionspherical equivalentfocal line 2vertical meridianretina
Two perpendicular meridians of the eye have different refractive powers. Light passing through them focuses at two different distances, forming the diagram above. There's no single sharp image — the best the eye gets is the circle of least confusion (spherical equivalent). To measure each meridian's power separately, this tool walks you through six striped patterns rotated to test six meridians, one at a time.

What this measures

Cylinder magnitude and axis for each eye, using rotating striped patterns. The cm method extended to direction: a grating only carries spatial information perpendicular to its stripes, so rotating it tests the eye one meridian at a time. The blur edge at each rotation is that meridian's far point.

Six meridians per eye, three quick captures per meridian. Takes about 8–10 minutes. Best done first thing in the morning when accommodation is at its loosest, in a normally-lit room, alone in the quiet (this is a focus exercise).

You'll need: a screen you can back away from (≥ 1.5 m of clear space behind you), a credit card or national ID, your camera permission, and your current correction OFF.

This is not a clinical eye exam. It measures the same two numbers an optometrist reads off an autorefractor — sphere and cylinder per meridian — but at home, with less precision and without any check on eye health. See a licensed optometrist for full eye-health screening.

Limitations & disclaimer

EndMyopia treats myopia as a refractive state, not a medical condition. This is a free educational tool — not medical advice, diagnosis, or a substitute for a licensed optometrist. Measurements depend on camera quality and how carefully you mark the card edges; expect ±5–10 % on laptops, ±10–15 % on phones. For lens orders, eye health concerns, or any task requiring full 20/20 vision, see a licensed professional.