Reviewed by Jonathan Miu, B Optom / B Sci, Kellyville Optical
Astigmatism is a common focusing problem where the front of the eye (the cornea) or the lens inside it is shaped more like a rugby ball than a soccer ball. Because it curves more in one direction than the other, light focuses at more than one point, making vision blurry or stretched at any distance. Most people have a small amount of astigmatism, and it's usually easy to correct with glasses or contact lenses.
This guide explains what astigmatism is, the signs to look for, how it's tested and the options for clear, comfortable vision.
Astigmatism at a glance
- What it is: an uneven curve on the cornea or lens that stops light focusing on a single point on the retina.
- How it feels: blurry or slightly stretched vision near and far, eye strain, headaches, squinting, and glare or halos around lights at night.
- Causes: most people are born with it. It can also follow an eye injury or surgery, or come from a condition such as keratoconus.
- How common: very. It often occurs alongside short-sightedness (myopia) or long-sightedness (hyperopia).
- How it’s found: during a regular eye test. It shows as the CYL and AXIS numbers on your prescription.
- Correction: glasses or toric contact lenses suit most people. Rigid contact lenses or laser surgery may be options in some cases.
- Children: uncorrected astigmatism can affect learning and, in some children, lead to a lazy eye (amblyopia), so an eye test before starting school is worthwhile.
Frequently asked questions
Astigmatism makes vision look blurry, smeared or slightly stretched, at both near and far distances. Letters can look shadowed or doubled, and straight lines may seem tilted. At night, lights can look star-shaped or have streaks, glare or halos around them. Mild astigmatism may cause no obvious blur but can still lead to tired eyes and headaches.
No. Short-sightedness (myopia) blurs distance vision because the eye focuses light in front of the retina. Astigmatism blurs vision at all distances because the eye’s uneven curve focuses light at more than one point. Many people have both, and a single pair of glasses or contact lenses can correct them together.
Astigmatism usually stays fairly stable through adulthood, though it can change slowly with age. A noticeable or steady increase can be a sign of a corneal condition such as keratoconus, especially in teenagers and young adults. Regular eye tests help your optometrist track any change and update your prescription when needed.
Not always. Mild astigmatism may not need correcting if your vision is clear and comfortable. Glasses can help if you notice blur, eye strain, headaches or glare when driving at night, or spend long hours on screens or reading. Your optometrist can advise whether correction is likely to help you.
Yes. Toric soft contact lenses are designed for astigmatism and are weighted to stay in the right position on the eye. Rigid gas permeable (RGP) lenses are another option, particularly for higher or irregular astigmatism. A contact lens fitting checks which lens suits your eyes and prescription.
Laser eye surgery, such as LASIK or PRK, can reshape the cornea to reduce astigmatism in suitable adults. It’s assessed and performed by an ophthalmologist, and isn’t right for everyone. Lens surgery, including a toric lens during cataract surgery, can also correct astigmatism. Glasses and contact lenses remain the most common options.
Astigmatism often runs in families, and most people with it are born with some degree of it. If a parent has significant astigmatism, it’s worth having children’s eyes tested early, ideally before they start school.
No. Screens and reading in dim light don’t cause astigmatism. They can make existing astigmatism more noticeable, because focusing for long periods can lead to tired eyes, blur and headaches. Correcting astigmatism and taking regular screen breaks can help. Read more about digital eye strain.
What causes astigmatism?
Astigmatism is caused by an uneven curve on the cornea (corneal astigmatism) or, less often, the lens inside the eye (lenticular astigmatism). Instead of being evenly round, the surface is steeper in one direction than the other. Light passing through it focuses at two points rather than one, which blurs vision.
Most astigmatism is present from birth and often runs in families. Less common causes include:
- An eye injury or scarring on the cornea
- Eye surgery, including cataract surgery
- Keratoconus, a condition where the cornea gradually thins and bulges into a cone shape. We can check for this at Kellyville Optical with a corneal topographer.
- Changes in the lens with age
What are the symptoms of astigmatism?
The most common symptom of astigmatism is blurred or distorted vision at all distances. Other signs include:
- Eye strain or tired eyes, especially after reading or screen use
- Headaches, often around the forehead or temples
- Squinting to see clearly
- Star-shaped lights, glare, streaks or halos, making night driving harder
- Letters that look shadowed, doubled or smeared
Children rarely complain about blurry vision, because they assume everyone sees the same way. Signs to watch for include squinting, sitting close to the TV, tilting the head, rubbing the eyes, headaches, or losing interest in reading.
How is astigmatism diagnosed?
Astigmatism is diagnosed during a comprehensive eye test. Your optometrist measures how clearly you see, checks how your eyes focus light, and measures the curve of the front of your eye. Testing is painless and doesn’t require eye drops for most adults.
On your prescription, astigmatism shows as two numbers. CYL (cylinder) is how much astigmatism there is, and AXIS is its direction, from 0 to 180 degrees. Learn more in our guide to reading your eye prescription.
If your astigmatism is high, irregular or changing, our optometrists can map the shape of your cornea in house with a corneal topographer to check for keratoconus, and refer you to an ophthalmologist if needed.
How is astigmatism treated?
Astigmatism is treated by correcting the way light focuses on the retina. The right option depends on how much astigmatism you have, your lifestyle and your eye health.
Glasses are the simplest option for most people. Lenses are made with a cylinder power set at a precise angle to balance the uneven curve. Getting the axis exactly right matters, so accurate measurements and well-fitted frames make a real difference. Explore our prescription lens options.
Toric soft contact lenses correct astigmatism and are designed to stay in the right orientation on the eye. They’re available in daily disposable and monthly options for many prescriptions.
Rigid gas permeable (RGP) lenses keep their shape on the eye and can give sharper vision for higher or irregular astigmatism, such as with keratoconus. Read more about RGP lenses.
Orthokeratology (ortho-k) uses special lenses worn overnight to gently reshape the cornea, so you can see clearly during the day without glasses. It’s mainly used for short-sightedness, and some designs can also correct lower amounts of astigmatism. Learn more about ortho-k.
Laser or lens surgery can reduce astigmatism in suitable adults whose prescription is stable. Suitability is assessed by an ophthalmologist.
Astigmatism in children
Astigmatism is common in children. Mild amounts often need no treatment, while higher amounts can blur vision enough to affect reading, learning and sport. If one eye has much more astigmatism than the other, or both eyes have high astigmatism, the brain may not learn to see clearly through that eye, leading to a lazy eye (amblyopia).
Early detection gives the best chance of normal vision development. An eye test before your child starts school, and regular checks after that, can pick up astigmatism before it affects learning. Read more about amblyopia (lazy eye).
When should you see an optometrist?
Book an eye test if you notice blurry or distorted vision, frequent headaches or eye strain, or glare when driving at night. Also book if your current glasses no longer feel as sharp. See your optometrist sooner if your vision changes quickly, or if your child’s astigmatism or prescription keeps increasing.
