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Astigmatism

Astigmatism

Astigmatism is common, and very correctable.

Astigmatism means the front of the eye (the cornea), or sometimes the lens inside it, is curved more in one direction than the other, more like a football than a basketball. Light focuses on two points instead of one, so vision is blurred or stretched at every distance.

Most people have at least a little astigmatism. It isn’t an eye disease, and in nearly everyone it’s easily corrected with glasses or contact lenses.

Symptoms

  • Blurry or slightly doubled vision, far away and up close
  • Streaks or starbursts around headlights and streetlights at night
  • Squinting to sharpen things
  • Eye strain and headaches, especially after reading, screens or driving
  • Letters that look smeared or “ghosted”

Regular vs. irregular astigmatism

Regular astigmatismThe common kind. The cornea has two even curves at right angles. Glasses and standard toric contacts correct it fully.
Irregular astigmatismThe cornea is uneven, from keratoconus, scarring or past eye surgery. Glasses can’t fully correct it, but scleral and other specialty contact lenses often can.

We map the shape of the cornea with corneal topography (our Marco OPD-3 measures both corneal shape and how the eye focuses light), which shows which type you have.

Can astigmatism cause headaches?

Yes. Uncorrected or under-corrected astigmatism makes the eyes and focusing muscles work harder to sharpen a blurred image. That effort can cause eye strain and headaches, often around the forehead or temples, and worse after reading, screen time or driving. An accurate, up-to-date prescription usually brings relief. Read more in Can astigmatism cause headaches? and headaches and eye strain.

Astigmatism in children

Children rarely complain about astigmatism because they’ve never seen any other way. A significant amount that isn’t corrected while vision is developing can lead to amblyopia (lazy eye) in one or both eyes. That’s one more reason for kids’ eye exams before school, even when a child passes a screening.

How to read your prescription

On your prescriptionWhat it means
OD / OSRight eye / left eye (from the Latin oculus dexter and oculus sinister). OU means both eyes.
SPH (sphere)The main power. A minus number (−2.00) means nearsighted; a plus number (+1.50) means farsighted.
CYL (cylinder)The amount of astigmatism. Blank means none.
AXISThe direction of the astigmatism, from 1 to 180 degrees. It only matters if there’s a CYL number.
ADDExtra reading power for bifocals or progressives, usually after 40.
PRISMShifts the image to help the two eyes work together, if needed.

For example, −1.25 −0.75 × 180 means a little nearsighted, with 0.75 of astigmatism at 180 degrees.

Correction options

  • Glasses with the cylinder and axis built in. Precise measurement matters: a few degrees of axis error is enough to cause strain. Our automated phoropters and digital refraction make that fine-tuning faster and more repeatable.
  • Toric soft contact lenses, designed to stay rotated in the right position. Daily disposable torics are widely available. See contact lenses.
  • Specialty lenses (scleral or rigid gas permeable) for irregular astigmatism.
  • Refractive surgery (LASIK, PRK or toric lens implants at cataract surgery). We refer to surgeons and co-manage your care.

Myths

“I can’t wear contacts with astigmatism.”Most people can. Toric contacts correct most astigmatism, and specialty lenses handle the rest.
“Astigmatism will get worse if I wear glasses.”No. Glasses don’t change the shape of the eye. They just correct it while you wear them.
“Reading in dim light causes astigmatism.”No. It’s mostly the shape you were born with, though it can change slowly over the years.
“A little astigmatism doesn’t matter.”Even small amounts can cause strain and headaches with long screen days or night driving.

Common questions

What is astigmatism?

Astigmatism is a common focusing error where the cornea or lens is curved more in one direction than the other, like a football, so light focuses at two points. It blurs or stretches vision at all distances and is corrected with glasses or contact lenses.

Can astigmatism cause headaches?

Yes. Uncorrected astigmatism makes the eyes work harder to see clearly, which can cause eye strain and headaches, often around the forehead or temples and worse after reading, screens or driving. An updated prescription usually helps.

Can I wear contact lenses if I have astigmatism?

Usually yes. Toric soft contact lenses correct most astigmatism, including daily disposables, and scleral or rigid lenses correct irregular astigmatism from keratoconus or scarring.

What do CYL and AXIS mean on my prescription?

CYL (cylinder) is the amount of astigmatism, and AXIS is its direction in degrees from 1 to 180. If the CYL box is blank, you have no meaningful astigmatism in that eye.

Does astigmatism get worse over time?

It usually stays fairly stable, though it can change gradually with age. A rapidly increasing or irregular astigmatism, especially in teens and young adults, should be checked for keratoconus.

Medically reviewed by Dr. Christopher Tumolo, O.D., L.D.O. · Last reviewed

Sources

  1. National Eye Institute: Astigmatism
  2. American Academy of Ophthalmology: What Is Astigmatism?
  3. American Optometric Association: Astigmatism

This page is general education, not a diagnosis. Same-day appointments are available during office hours.