What do cylinder and axis mean on my prescription? Astigmatism explained

You get your prescription slip and see columns of numbers: SPH, CYL, AXIS, ADD. Sphere is the one most people recognise. Cylinder and axis are the ones that raise questions, especially when yours are filled in. If they are, you have astigmatism. This article explains what that means in plain words.

What is astigmatism?

Astigmatism is a common refractive condition. The front surface of the eye, or the lens inside it, is curved more in one direction than the other. Think of a rugby ball rather than a football. Light does not focus to one single point, so things look blurred or stretched at some distances. It is not a disease and it is not caused by reading in dim light or by screens.

Astigmatism often comes together with short-sightedness or long-sightedness. Many Filipinos who wear glasses have a little of it. Only an eye exam shows how much.

What is cylinder (CYL)?

Cylinder is the amount of astigmatism correction your eye needs. A small number means a mild difference between the two directions. A larger number means a bigger difference, which usually means blur or distortion is more noticeable without correction. The number may be written with a minus or a plus sign, depending on how your optometrist records it. Both forms describe the same correction.

What is axis?

Axis is a number from 1 to 180. It tells the lab where to place the cylinder power, measured in degrees. Axis only appears when there is a cylinder value. Axis 90 and axis 180 are very different positions, so the lab needs the exact number. A lens cut a few degrees off can leave you with blur or discomfort even when the numbers look right on paper.

Why accuracy matters more with astigmatism

With a sphere-only prescription, a small error in how the lens sits in the frame matters little. With cylinder and axis, rotation matters. A lens that is turned a few degrees from its intended axis changes what you see. That is why a made-to-measure lens and careful fitting matter. It is also why the frame must hold the lens steadily. A bent or loose frame can rotate the lens slightly over time. Free lifetime custom fitting and adjustment helps keep the frame where it should be.

Common questions

• Does astigmatism get worse? It can change over time, which is one reason regular eye tests matter. Your optometrist tracks it at each exam.
• Why do my new glasses feel strange? A new cylinder or axis can feel odd for a few days. Objects may look tilted or stretched at first. Wear them consistently. If the feeling continues beyond about two weeks, return to the store so the team can check the fit and the prescription.
• Can I use my old prescription? Not for a new pair. Your cylinder and axis may have changed. A current exam is the only reliable source.
• Do both eyes have the same astigmatism? Often not. Each eye has its own cylinder and axis values.

Which lens suits astigmatism?

For spectacles, our team names Shamir Opulens Exact. It is a Starter-tier single vision lens made in Israel, with a lead time of 7 to 9 days, and it is made to measurement so the cylinder and axis are cut precisely. It is also the lens we name when your prescription has just changed, and it can be ordered polarized if you need glare control for driving or riding.

If you need glasses sooner, ask the team which of the in-stock lenses can cover your prescription. Not every cylinder strength is available off the shelf, so confirm at the counter. A higher cylinder or a strong prescription may call for a made-to-order lens.

A day in Manila with astigmatism

Night driving is where many people first notice it. Headlights streak, street signs look doubled, and tail lights seem to spread. If you notice this, tell your optometrist at the exam. It is useful information. Glare and halos can have other causes too, so we never guess from symptoms alone. A full Vision7 exam sorts out which cause applies.

What the Vision7 exam does for astigmatism

Objective refraction gives a starting estimate of your cylinder and axis. Subjective refraction fine-tunes them with your feedback, which is where small adjustments of a few degrees get made. The visual health exam then checks the surface of the eye, because the shape of the cornea is what usually causes astigmatism. Seven steps in total, done by a licensed optometrist.

Book your Vision7 eye test

Book a Vision7 eye test at your nearest Vision Express store. The exam fine-tunes your cylinder and axis and checks the health of the front of your eye. Then ask for Shamir Opulens Exact at the counter, a made-to-measure lens that cuts your cylinder and axis precisely. Every pair includes free lifetime ultrasonic cleaning, free lifetime custom fitting and adjustment, and a 1-year warranty.