What Is Astigmatism? Symptoms, Causes & How It Is Corrected

Updated: 1 September 2026 · By the Eye-Shop opticians · This article does not replace an eye examination.

If images look distorted or blurred at every distance — both near and far — or if you squint to sharpen the picture and get headaches when reading, the most likely name for the problem is astigmatism. It is one of the most common refractive errors: almost all of us have a small amount, and it often coexists with myopia or hyperopia.

What exactly happens in the eye

Normally the cornea — the transparent "windscreen" at the front of the eye — is evenly curved in every direction, like part of a basketball. In astigmatism the curvature differs by direction — the shape is more like a rugby ball. Light passing through the steeper meridian focuses at a different point from light through the flatter one, so the eye cannot form a single sharp image: the picture is clear in one direction and blurred in the other, as if you were looking into a slightly distorting mirror. The exact causes of the uneven curvature are not fully known, but there is a clear hereditary tendency. More rarely, astigmatism comes from the crystalline lens (lenticular astigmatism) or from corneal conditions such as keratoconus.

How someone with astigmatism sees

• Blurred/distorted vision at all distances — not only far (myopia) or only near (hyperopia).
• Haloes and rays around lights at night — the classic complaint when driving.
• Eye strain, headaches and squinting after reading or hours on a screen.
• At low degrees there may be no strong symptom — only "tired" vision at the end of the day.

Degrees of astigmatism: how much is "a lot"?

How to read your prescription

On the prescription, astigmatism appears in two fields next to the spherical power (SPH): CYL (cylinder — the amount of astigmatism, e.g. −1.25) and AXIS (its orientation in degrees, e.g. 180°). Example: SPH −2.50 / CYL −1.25 / AXIS 180° means 2.50 of myopia with 1.25 of astigmatism on a horizontal axis. Corrective lenses that combine both are called toric — they have a different power in each direction.

How astigmatism is corrected

• Prescription glasses: the simplest solution — lenses with a cylindrical correction on the right axis. At high degrees, thinned high-index lenses are worth it for looks and weight. Every prescription frame in our collection is made with the lenses of your prescription.
• Toric contact lenses: full correction without glasses — made to your cylinder and axis.
• Refractive (laser) surgery: for stable prescriptions in adults, after a full suitability assessment by an ophthalmologist.

Astigmatism together with myopia, hyperopia or presbyopia

Astigmatism rarely travels alone: most often it combines with myopia or hyperopia, and after 40-45 presbyopia is added too. A single pair of glasses (single-vision or progressive) corrects all combinations at once — just note that off-the-shelf ready readers do NOT correct astigmatism: for that you always need prescription lenses.

Does it get worse over the years?

Usually it changes very slowly or stays stable for life. A sudden or continuous increase in the cylinder needs an ophthalmological check (among other things, to rule out keratoconus). The general rule: an eye test every 1-2 years — see how often you should change your glasses.

Frames and prescription lenses for astigmatism

At Eye-Shop you will find the widest range of branded and value prescription frames suitable for every degree of astigmatism. With every frame you buy, we include the prescription lenses to your prescription free of charge.