Patient Basics: Astigmatism

Astigmatism is a common focusing problem that makes vision blurry or stretched at every distance. It happens when the clear front of the eye (the cornea) or the lens inside the eye is curved more like a football than a basketball, so light focuses in more than one place. Glasses, contact lenses or surgery can correct it.

Key points

• Most people have a little astigmatism. Many don’t need any correction.
• It is usually present from birth or early childhood and often runs in families.
• It is a long-lasting trait of the eye, not an illness. It tends to stay fairly stable, changing slowly over the years.
• Signs include blurry or distorted vision, eye strain, headaches, squinting and glare around lights at night.
• No eye drop or pill can change astigmatism. Glasses, contacts or surgery correct it.

What causes astigmatism

A normal cornea is evenly curved, like the side of a ball. With astigmatism, it is steeper in one direction than the other. Light passing through bends unevenly, so the image on the back of the eye is out of focus. Most astigmatism comes from the cornea. Less often, it comes from the lens inside the eye.

Causes include:

• Genes. Most people are born with it, and it often runs in families.
• Keratoconus. The cornea slowly thins and bulges forward into a cone. It usually starts in the teens or 20s and keeps getting worse for years. Rubbing the eyes hard is linked to it.
• Eye injury, infection or scarring of the cornea.
• Eye surgery, such as cataract surgery or a corneal transplant.
• A lump on the eyelid, such as a large chalazion, pressing on the cornea.

Reading in dim light or sitting close to a screen doesn’t cause astigmatism.

Astigmatism symptoms

• Blurry or distorted vision, both close up and far away
• Tired, strained eyes, especially after reading or screen use
• Headaches
• Squinting to see clearly
• Trouble seeing at night, with glare, halos or streaks around lights

Children often don’t know their vision is blurry. Signs in a child include trouble reading, avoiding close work, tilting the head, rubbing the eyes or sitting very close to things.

Blurry vision in one eye

The two eyes often have different amounts of astigmatism, so one eye can be blurrier than the other. Other common causes of blur in one eye are a difference in nearsightedness or farsightedness between the eyes, dry eye, and a cataract. Less common but serious causes include a detached retina, swelling of the optic nerve, a problem in the center of the retina (macula) or a stroke.

Blurry vision that comes on slowly needs an eye exam. Blurry vision that comes on suddenly needs emergency care.

How it’s diagnosed

An optometrist or ophthalmologist (eye doctor) checks for astigmatism during a routine eye exam. You read letters on a chart, then look through a series of lenses while you say which ones look clearer. This finds your prescription. A machine may also measure the curve of your cornea or make a detailed map of its surface, which helps find keratoconus.

On a glasses prescription, the “cylinder” (CYL) number shows how much astigmatism you have, and the “axis” shows its direction. A cylinder of -1.00, sometimes called “-1 astigmatism,” is a mild amount. Values above about 2 are often called high.

Astigmatism treatment

• No treatment. A small amount that doesn’t bother you can be left alone.
• Glasses. Lenses with extra curve in one direction cancel out the uneven focus.
• Soft toric contact lenses. These are shaped to correct astigmatism and weighted so they stay in the right position.
• Rigid gas permeable or scleral lenses. These hard lenses give the eye a smooth front surface. They work well for high or uneven astigmatism and keratoconus.
• Laser eye surgery. LASIK, PRK and SMILE reshape the cornea. You need to be an adult with a stable prescription and a healthy cornea. Possible problems include dry eye, glare at night and needing glasses anyway.
• Toric lens implant. During cataract surgery, the surgeon can place an artificial lens that also corrects astigmatism.
• Corneal cross-linking. For keratoconus, eye drops and ultraviolet light strengthen the cornea to stop it bulging further.

Astigmatism in children

If a young child has a lot of astigmatism that isn’t corrected, the brain may not learn to see clearly through that eye. This is called amblyopia (lazy eye). Glasses worn early, sometimes along with patching the stronger eye, can prevent or treat it. Children should have their vision checked at well-child visits, and a full eye exam if they fail a screening.

When to see an eye doctor

• Blurry vision, eye strain or headaches with reading or screens
• Vision that keeps getting worse, especially in a teen or young adult
• Your glasses no longer seem to help

Get emergency care for sudden vision loss or blur, a shadow or curtain over part of your vision, a burst of new floaters or flashes, sudden double vision, or eye pain.

Common questions about astigmatism

Is astigmatism a chronic condition?

Yes, in the sense that it lasts for life unless surgery changes it. It isn’t a disease, and in most people it doesn’t harm the eye. It is a difference in shape that glasses or contacts correct. Keratoconus is the exception, because it can keep getting worse.

Are you born with astigmatism or does it develop?

Most people are born with astigmatism or have it from early childhood, often because it runs in the family. It can also develop later from an eye injury, eye surgery, a scar on the cornea or keratoconus. Babies often have some astigmatism that lessens as their eyes grow.

Can astigmatism get worse?

It can change slowly with age, so your prescription may shift over the years. Faster changes, especially in teens and young adults, can be a sign of keratoconus and need an eye doctor’s attention. Wearing glasses or contacts doesn’t make astigmatism worse.

How common is astigmatism?

Very common. Most people have at least a small amount, and many adults have enough that glasses or contacts make their vision sharper. It often occurs along with nearsightedness or farsightedness, and all three can be corrected with the same pair of glasses.

Questions to ask your doctor

• How much astigmatism do I have, and in which eye?
• Do I need glasses all the time, or only for some tasks?
• Would toric or rigid contact lenses work for me?
• Am I a good candidate for laser surgery?
• Is there any sign of keratoconus?

Learn more

• Astigmatism (National Eye Institute)

This guide is general information and doesn’t replace advice from your own doctor. Last updated October 2026.