Astigmatism

Astigmatism is a common visual condition caused by an irregularly shaped eye that leads to blurred vision and difficulty seeing at night. Diagnosis involves a routine eye exam, and there are plenty of ways to manage the condition. Learn more on the causes, symptoms, and treatment options below.

What is astigmatism?

Astigmatism is a refractive error in the eye that causes blurry vision at all distances.

Having astigmatism means that the cornea or crystalline lens of your eye (or in some cases both) is irregularly shaped, like an egg or a rugby or football.

This causes your eye to focus on light at two separate points on the retina, the light‑sensitive layer at the back of your eye. As a result, your vision can become blurry or distorted.

Symptoms of astigmatism

While distorted vision is the most common sign of astigmatism, there are several other indicators. Some typical astigmatism symptoms include:

Blurry vision
Headaches
Visual fatigue
Eye strain
Squinting to see clearly
Glare, halos, or blur around lights at night

Many people with astigmatism run into difficulties when performing certain tasks, driving at night being one of them. In low light conditions, the blurry vision associated with astigmatism can become worse. That’s because when the lighting dims, your pupil dilates to let in more light. As the pupil dilates, more peripheral light rays enter the eye, which can cause drivers to experience even more blurry vision, as well as halos around bright lights and even night blindness. 

Additionally, bright headlights from oncoming and rear traffic can become particularly distorted, creating what appears like ‘lines’ of light around the headlight. Light reflections from cars and street lamps can also cause drivers with astigmatism to squint, making it more difficult to concentrate on the road ahead.  

What does astigmatism look like?

If you have astigmatism, your vision will likely be distorted. It can make printed words and letters on road signs appear blurred or cause a glare or ‘smear’ around lights, especially when driving at night.

If you notice any of these symptoms, it's important to book an eye exam. That way, an optometrist can test for astigmatism and detect any problems that might be causing poor vision.

What causes astigmatism?

The cause of astigmatism is not always clear, but this eye condition is most likely linked to your genetics. While most cases are hereditary, there are several reasons why someone might have astigmatism. These include:

Astigmatism from birth: people are usually born with astigmatism, and it’s more common in premature or low birth weight babies. Sometimes, as children grow and their eyes change shape, their astigmatism can improve.
Developmental factors: as children grow, the shape of their corneas can change, which can improve astigmatism or lead to the development of this eye condition. Because of this, it’s important to get an eye exam booked for your child to check for any symptoms early on.
Keratoconus: a progressive eye disease that can cause your cornea to thin and begin to bulge into a cone‑like shape. This can lead to astigmatism and other vision issues.
Eye surgery: some types of eye surgery can alter the shape of your cornea, which may lead to astigmatism.
Eye injury: scarring caused by trauma or injury to the eye can also change the shape of the cornea. This can then lead to astigmatism.
Corneal scar tissue: scarring of the cornea from infections or ulcers can also distort its shape and cause astigmatism.
Contact lens use: improper use of some contact lenses, especially rigid lenses, can change the cornea’s shape and cause astigmatism. Luckily, this is usually temporary, and you can often reverse this by stopping or correcting the use of lenses.

What causes astigmatism to worsen?

Astigmatism is a condition that typically doesn’t get worse over time, but it can change gradually with age. However, some factors which cause astigmatism itself can lead to your vision worsening more rapidly or irregularly. These include keratoconus and eye operations.

Sometimes astigmatism can also be caused by pressure on the eye from eyelid problems, like large cysts and infected glands. But this will usually reduce once any eyelid problems improve with treatment.

If you’re concerned about a change in your condition, regular eye exams are important to monitor and manage astigmatism effectively.

The different types of astigmatism

As well as a range of causes, there are a few different types of astigmatism. By identifying which type you have, an optometrist can manage the condition better and help you to choose the best corrective measures.

The most common type is known as regular corneal astigmatism. This means the cornea is curved more in one direction, like an egg or a rugby or football.

Irregular corneal astigmatism can happen when the cornea is curved in multiple directions, and/or the corneal surface of the eye is uneven, more commonly as a result of injury, damage or scarring.

Astigmatism can also be categorized as lenticular astigmatism, which is when the crystalline lens inside the eye causes astigmatism, rather than the cornea. It’s not unusual for astigmatism to be a combination of corneal and lenticular astigmatism.

The difference between astigmatism and myopia

Blurred vision can be caused by astigmatism and myopia, but the two are different conditions.

Astigmatism happens when the front part of your eye or the lens inside is misshaped. This causes everything to look blurry at any distance.

If you have myopia, or nearsightedness, you can see close objects clearly, but faraway things look blurry. This is because your eyeball is too long or the cornea is too curved, causing light to focus in front of the retina.

How is astigmatism diagnosed?

If you think you may have astigmatism or another eye condition, you should book an appointment with an optometrist. They will check for signs of astigmatism and recommend treatment that best suits your needs.

Learn more about what to expect during your eye exam.

Treatments for astigmatism

Astigmatism is a condition rather than an eye disease, and most cases can easily be corrected with glasses, specific contact lenses (called toric lenses) or surgery. Let’s look at each of these options in more detail:

Glasses: glasses are often used to treat most levels of astigmatism.
Contact lenses: if you don’t want to wear glasses, most cases of astigmatism can also be corrected with either soft or rigid contact lenses. With irregular astigmatism, which tends to be more common after an eye injury or in cases of keratoconus, the cornea can be uneven and curved in many ways. In this case, specialized, rigid contact lenses might be recommended.
Laser eye surgery: also known as refractive surgery, laser eye surgery can be used in certain cases of astigmatism as it corrects focusing problems by reshaping the cornea with a laser.
Clear lens extraction (CLE): another type of eye surgery which corrects vision problems like astigmatism, myopia and hyperopia. During the procedure, the eye’s natural lens is removed and replaced with an artificial intraocular lens (IOL). This new lens helps reduce or eliminate the need for glasses or contact lenses.

Choosing the right treatment option for your astigmatism will depend on many different factors, but your optometrist will help you decide on the right option for you.

What happens if astigmatism is left untreated?

As mentioned, astigmatism isn’t an eye disease, it’s primarily a refractive error. However, if left undetected or untreated, it has the potential to lead to other eye health issues or worsen existing ones such as amblyopia (lazy eye).

This is a condition where the brain favours one eye during early development. This usually happens early in life, so regular eye exams for children are important to catch any potential issues.

Can astigmatism be prevented?

Astigmatism is often genetic, so there’s no guaranteed way to prevent it. However, there are steps you can take to maintain healthy eyes and potentially minimize the progression of this condition. These include:

Regular eye exams
Wearing protective eyewear during activities that could harm your eyes (to prevent injuries that might result in astigmatism).

Next steps

Astigmatism is a common eye condition that affects a large portion of the population. It leads to blurred vision and can also cause additional symptoms such as eye strain or discomfort. In some cases, it can even lead to further complications if not correctly managed.

We want to help keep your eyes healthy for as long as possible. If your optometrist detects any signs of an eye condition during your comprehensive eye exams, they will determine an appropriate management plan that suits your needs.

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Written with care and check for accuracy

Dr. Tracy Weng

Dr. Tracy Weng is a Doctor of Optometry practicing in Canada, providing comprehensive eye care at the Specsavers Kitsilano location. She is a member of the Canadian Association of Optometrists and BC Doctors of Optometry, and serves on multiple committees with the College of Health and Care Professionals of BC. Dr. Weng is committed to delivering personalized, evidence‑based care while also supporting the growth of the profession through mentorship, continuing education, and professional collaboration.

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