Eye condition · Focusing problems
Astigmatism
Astigmatism blurs and distorts vision at every distance. Learn what causes it, the symptoms, and how glasses, contacts and surgery correct it.
What it is
In an eye without astigmatism, the cornea is curved evenly in every direction, like a basketball. With astigmatism, it is curved more steeply in one direction, more like a rugby ball, or the lens inside the eye is shaped unevenly. Light focuses at two different points, so vision is blurred or stretched at every distance.
Astigmatism is very common. Most people have a small amount, and it often occurs together with nearsightedness or farsightedness.
Symptoms
- Blurry or distorted vision, near and far
- Eye strain and headaches, especially after reading or screen work
- Squinting
- Trouble seeing at night, with streaks or halos around lights
Who is at risk
Most astigmatism is present from birth and may run in families. It can also follow an eye injury, eye surgery or a corneal disease such as keratoconus.
How it is diagnosed
An eye exam measures it with a refraction, a keratometer or a corneal map (topography). On a prescription it appears as the CYL (strength) and AXIS (direction) numbers. Our prescription decoder explains them.
Treatment
- Glasses with a cylindrical correction
- Toric soft contact lenses, which are weighted to stay in the right orientation
- Rigid gas-permeable or scleral lenses, which give the eye a smooth new front surface
- Refractive surgery such as LASIK, PRK or SMILE, or a toric implantable lens
- Toric lens implants during cataract surgery
Mild astigmatism with no symptoms may not need treatment at all.
Watch
Questions people ask
Is astigmatism serious?
Usually not. It is a common focusing error that is easy to correct. Astigmatism that changes quickly in a teen or young adult can be a sign of keratoconus and should be checked.
Can I wear contacts with astigmatism?
Yes. Toric soft contact lenses and rigid gas-permeable lenses both correct astigmatism.