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

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

Symptoms of astigmatism

While blurred vision is the most common sign of astigmatism, there are a number of other indicators. Typical symptoms of astigmatism include:

What does astigmatism look like?

Astigmatism can look like blurred printed words and letters on road signs, or cause a glare or ‘smear’ around lights, especially when driving at night.

If you notice any of these symptoms, it's important to schedule an eye test to detect any problems and prevent any potential accidents that poor vision can cause, particularly while driving.

What causes astigmatism?

While most astigmatism cases are hereditary and genetic, there are several causes that may lead to the condition including:

Astigmatism from birth: People are usually born with astigmatism, which is more common in premature or low birth weight babies. Many children are born with astigmatism, but as they grow and their eyes change shape, it can improve with age.
Developmental factors: As children grow, the shape of their corneas can change, which can lead to the development of this eye condition. It’s important to test children’s eyes early to catch any symptoms early on.
Keratoconus: Keratoconus is a progressive eye disease in which your cornea thins and begins to bulge into a cone‑like shape, causing astigmatism and other vision issues.
Eye surgery: Some types of eye surgery, including cataract surgery, can alter the cornea's shape and may lead to astigmatism.
Eye injury: Trauma or injury to the eye can cause scarring or change the shape of the cornea, which can lead to astigmatism.
Corneal scar tissue: Scarring of the cornea from infections or ulcers can distort its shape and cause astigmatism.
Contact lenses: Improper use of some contact lenses, especially rigid lenses, can temporarily change the cornea’s shape and cause astigmatism. You can often reverse this condition by stopping or correcting the use of lenses. Always put in contact lenses correctly to help avoid any damage to the eye.

What causes astigmatism to worsen?

Many of the factors that cause astigmatism itself, can also lead to astigmatism worsening, including, aging, keratoconus, eye operations, eye fatigue, and incorrect usage of contact lenses. Regular eye exams are important to monitor and manage astigmatism effectively.

The different types of astigmatism

Understanding the different types of astigmatism can help you manage the condition better and help you to choose the best corrective measures.

The main types of astigmatism include:

Corneal: The front part of your eye, called the cornea, is shaped like a rugby ball instead of being round, making things look blurry because the light isn't focused correctly.
Lenticular: The lens inside your eye is oddly shaped, causing vision problems even if the cornea is normal.
Myopic: Your eye is nearsighted in one or both main directions, making things look blurry.
Hyperopic: Your eye is farsighted in one or both main directions, causing vision issues.
Mixed: One direction of your eye is nearsighted, and the other is farsighted, making everything look blurry.

The difference between astigmatism and myopia

Astigmatism and myopia both cause blurry vision but the two are different. Astigmatism happens when the front part of your eye or the lens inside is misshaped, making everything look blurry at any distance.

Myopia, or near‑sightedness, means you can see close objects clearly, but faraway things look blurry because your eyeball is too long or the cornea is too curved, causing light to focus in front of the retina.

Testing and diagnosing astigmatism

If you think you may have an astigmatism or another eye condition, book an appointment as soon as you can. Our eye specialists can quickly diagnose and recommend treatment that best suits your needs.

Diagnosis involves a routine eye test where your optometrist will discuss any concerns and perform pre‑test exams. After, they will conduct a comprehensive refraction assessing the shape and power of the eye to help detect astigmatism. Based on the results, the optometrist will suggest a suitable treatment plan.

Learn more about what to expect during your eye test with our detailed guide.

Treatment for astigmatism

Most cases of astigmatism can be easily corrected through glasses, specialised contact lenses (called toric lenses) or refractive surgery. Let’s look at each of the treatments for this condition in more detail:

Glasses: Glasses are often used to treat regular astigmatism. Glasses specifically tailored to the irregular shape of your cornea or lens will help provide you with a clearer and more focused vision.
Contact lenses for astigmatism: With irregular astigmatism, which tends to be more common after an eye injury or in cases of keratoconus, the cornea will be uneven and curved in many ways. In this case, contact lenses may be the best solution to even out the irregularities in the cornea.
Laser eye surgery: Also known as refractive surgery, laser eye surgery corrects focusing problems by reshaping the cornea with a laser.
Clear lens extraction (CLE): Clear lens extraction is a surgery to correct 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 for your astigmatism can depend on many different factors the severity of the condition and personal preferences. Our eye specialists will be happy to answer any of your questions and guide you if you are unsure.

What happens if astigmatism is left untreated?

Astigmatism itself is primarily a refractive error as opposed to an eye disease. However, if left undetected or untreated, it has the potential to lead to other eye health issues or worsen existing ones such as:

Lazy eye (amblyopia): Astigmatism in one eye can lead to amblyopia, where the brain favours one eye during early development. Early eye testing for children is important to pick up any potential issues.
Strabismus (squint): Uncorrected astigmatism can cause strabismus, a condition where the eyes do not align properly due to unequal focusing efforts needed to compensate for blurred vision caused by astigmatism.

Can astigmatism be prevented?

There is no guaranteed way to prevent astigmatism. However, there are steps you can take to maintain healthy eyes and potentially minimise the progression of this condition, including:

Regular eye examinations.
Wearing protective eye wear during activities that could harm your eyes to prevent injuries that might result in astigmatism.

While these practices can support your eye health, it’s important to note that they cannot change a genetic predisposition to astigmatism.

Conclusion

Astigmatism is a common eye condition that affects a large portion of the population. Those with the condition will often encounter blurred vision and may also experience additional symptoms such as eye strain or discomfort, and in some cases, it can lead to further complications if not if not correctly managed.

Undergoing regular eye examinations is key to receiving an accurate diagnosis and getting the most appropriate advice when it comes to managing your astigmatism. Be sure to visit your local Specsavers for a chat with one our optometrists if you want further advice.

FAQs

About the author

Ross Campbell

BSc Hons MCOptom Prof Cert Glauc Prof Cert Med Ret

Ross is an experienced optometrist having graduated in 2007 from Bradford University. He is also ophthalmic director of Specsavers Swaledale & Northallerton, a pre‑registration supervisor, professional advancement consultant, and a WOPEC Lead Assessor. He has previously worked as Director of Optometry Advancement for Specsavers and as a columnist for Optician & ProFile magazine.

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What is astigmatism?