Eye Education

All About Astigmatism

Did you know 70% of prescriptions in the U.S. correct for some form of astigmatism? Astigmatism is one of the most common vision conditions, but it’s still very misunderstood.

We’re here to walk through everything anyone needs to know about what astigmatism is (and isn’t).

What is astigmatism?

We’ve all heard the classic astigmatism definition, “it’s when your eye is shaped more like a football instead of a sphere”–but it’s so much more!

Astigmatism is considered a refractive error because it affects the way your eyes bend (or refract) light. Eyes with astigmatism can’t evenly focus light onto the retina. When light passes through your cornea into your eye, it either focuses on your retina, above your retina, below your retina or way behind it.

Astigmatism happens when the light decides it doesn’t want to play by the rules and instead finds its way above and below and anywhere but focused on your retina.

There are two types of astigmatism—hyperopic or myopic.

  • Myopic: The most common type of astigmatism combines two refractive errors. When eyes have astigmatism and are nearsighted, they are classified as having myopic astigmatism.
  • Hyperopic: Another combination of two refractive errors. When eyes are both have astigmatism and are farsighted, they are classified as having hyperopic astigmatism.
  • Mixed: This bonus classification of astigmatism is caused when one eye is myopic and the other is hyperopic.

Astigmatism can also be classified as regular or irregular.

Regular astigmatism is the most common and causes the causes your eye to develop the football shape associated with astigmatism.

Irregular astigmatisms can be caused by damage to the cornea from a surgical procedure on the eye, other corneal trauma or keratoconus, which causes the cornea to gradually thin. This causes your cornea to gradually become shaped like a cone.

What causes astigmatism?

Astigmatism is caused by an uneven curve or either your cornea or lens. This uneven curvature causes images to focus both in front of and beyond the retina. This causes objects to appear blurry whether they are close or far away.

Doctors don’t know the exact cause of astigmatism, but they know genetics play a large part. Whether or not you’re likely to develop astigmatism is inherited from one or both parents (thanks, mom and dad!) Astigmatism can also develop after an eye injury, eye surgery, or eye illness.

There are also plenty of myths about the causes of astigmatism, so here’s a short list of things that don’t cause or worsen astigmatism:

  • Reading in low light
  • Sitting too close to the TV
  • Spending too much time on the computer
  • Squinting to read from a screen or book
  • Dreaming about playing football (ok, this one was just for fun)

Because astigmatism is usually inherited, most people start showing symptoms in adolescence whether they’re aware of what’s happening or not.

How do I know if I have astigmatism?

There are lots of indicators that you might have astigmatism. A few of the most common symptoms are:

  • Blurry vision
  • Eyestrain
  • Difficulty driving at night
  • Squinting
  • Headaches

If you’re an adult, it’s possible that you’ve been living with mild astigmatism and haven’t noticed. However, it’s possible to experience these symptoms without astigmatism. The best way to tell if you have astigmatism is to talk to an expert and see your optometrist.

It’s especially important to take children to the optometrist to check for astigmatism. Children often don’t realize their vision is anything other than normal. The sooner astigmatism is diagnosed, the better to prevent further complications in the future.

Can people with astigmatism wear contacts?

Another common myth about astigmatism is that it prevents us from wearing contacts. Ultimately it’s up to your optometrist to determine if you’re right for contacts, and plenty of people with astigmatism wear contacts.

Your optometrist can correct for mild astigmatism easily. For more severe astigmatism, options have opened up with XR (extended range) toric lenses. These lenses are weighted to counteract the tricky shape of astigmatic eyes.

The process for trialing and receiving toric lenses takes longer than usual because they’re custom made for unique astigmatic eyes, but that doesn’t mean folks with astigmatism can’t wear contacts.

Feel like it’s time to go get your eyes checked? Sign up for Sightbox and we’ll set you up with a highly-rated optometrist near you!