Can Laser Eye Surgery Fix Astigmatism?

How laser eye surgery corrects astigmatism

Laser eye surgery corrects astigmatism by reshaping the cornea so light can focus more clearly on the retina.

With astigmatism, the cornea curves more in one direction than the other. That uneven shape changes how light focuses inside the eye, which is why vision often appears distorted or shadowed rather than simply blurry.

Two parts of your prescription are used to plan the treatment. The cylinder (CYL) measures how strong the astigmatism is, while the axis shows the direction of the uneven curve across the cornea. Together, these measurements allow the laser to make the steeper part of the cornea flatter, which helps light focus more evenly inside the eye.

As the surface becomes more even, your vision usually becomes clearer. Distortion and shadowing caused by astigmatism are often reduced as well.

How much astigmatism can be treated?

Most levels of astigmatism can be treated with laser eye surgery, but there's no universal upper limit. Your consultant will consider how much astigmatism has been detected and the shape of your cornea. They’ll also assess whether there's enough tissue to support the reshaping safely.

Astigmatism is often grouped into severity:

• Lower astigmatism: up to around 1.00–1.50 dioptres
• Moderate astigmatism: around 1.50–3.00 dioptres
• Higher astigmatism: above 3.00 dioptres

Lower levels are the least complicated to treat. This is because the amount of reshaping required is smaller, which makes the result more consistent. The smaller amount of reshaping increases the likelihood of removing the astigmatism completely or reducing it to a level that doesn’t affect your vision without glasses.

Moderate levels also respond well to treatment. Results are generally good, but there's slightly more variation in how much of the astigmatism is cleared compared with lower prescriptions. Most people in this range get on well without glasses for everyday tasks, even if a small amount is still noticeable when their prescription is checked afterwards.

Higher levels of astigmatism require more of the cornea to be reshaped. This makes corneal thickness more important, and means the surface needs to be regular enough for accurate correction. Both affect whether treatment is suitable and how consistent the result is likely to be.

Irregular astigmatism is assessed differently. Instead of one clear pattern, the surface of the cornea is uneven in a way that’s harder to map and correct.  When this is present, standard laser treatment may not be a suitable treatment. Patients will need further assessment to decide whether laser treatment is possible or if another option would be more suitable for them.

A higher prescription doesn’t rule treatment out on its own. What matters is whether it can be corrected safely and whether the result will make a noticeable difference to how you see day to day.

Can astigmatism and short or long sight be corrected together?

Many people with astigmatism also have short-sightedness (myopia) or long-sightedness (hyperopia), and laser eye surgery can treat them at the same time.

The treatment is designed around the full prescription, so both problems can be corrected together. One part of the laser treatment adjusts your overall focus, while another corrects the uneven curve caused by the astigmatism. Because both prescriptions are being corrected at the same time, the final result depends on how the prescription works as a whole rather than any single part on its own.

For someone with mild astigmatism alongside myopia, the astigmatism is usually a smaller part of their overall prescription. In these cases, the results tend to be more predictable, and it’s common for both to be fully corrected or reduced to a level that doesn’t affect everyday vision.

For someone with higher astigmatism combined with hyperopia, both the strength of the prescription and the uneven focus caused by the astigmatism need to be corrected at the same time. This requires more reshaping of the cornea. Results can still be very good, although there is usually a little more variation in how close the final correction comes to the intended target.

Which procedure is best for astigmatism?

The best procedure for astigmatism depends on what needs correcting and how your cornea can be treated safely. It’s chosen to achieve an accurate result while keeping the eye stable after treatment.

LASIK

LASIK is often used when the cornea is thick enough to safely create a thin flap and reshape the tissue beneath it. Working below the surface allows for very precise adjustment of the strength and direction of astigmatism. It’s commonly recommended across a wide range of prescriptions where the goal is an accurate treatment with a relatively short recovery time. 

SMILE / SmartSight

SMILE and SmartSight correct vision by removing a small piece of tissue from within the cornea through a keyhole opening, without creating a flap. This approach is useful where preserving corneal strength is important, as the surface structure is largely left intact, and is often considered for some people with myopia and astigmatism, depending on how the prescription is balanced.

PRK / LASEK

PRK and LASEK reshape the surface of the cornea after the outer layer has been gently moved or removed. These options are usually considered when the cornea is thinner or when a flap-based procedure isn’t suitable. Both approaches can treat astigmatism effectively, but the recovery time is slower as the surface needs time to heal. 

What results can you expect?

Most people notice a clear improvement in their vision within the first few days after treatment, although, depending on which procedure they had,  it can take a little longer for things to fully settle. 

Results are often summarised using a single figure, but that doesn’t help you to understand how your vision will feel day to day. Outcomes are usually described in three overlapping ways:

Visual acuity is a measure of how sharp your vision is. It’s expressed as a ratio, such as 6/6 (considered clear vision) or 6/12 (which meets the UK legal standard for driving). These measurements show how well you can see without glasses.

Residual astigmatism refers to how much astigmatism is left after treatment. Results are often described by how close they are to the intended prescription, measured in dioptres (D), usually within ±0.50D or ±1.00D. Being within ±0.50D means that your vision should be clear without glasses. Within ±1.00D is still considered a good result and is often enough for comfortable vision in most situations.

Glasses independence is about how often you still need glasses after treatment, rather than being a specific measurement. Some people stop using them for most daily activities, while others still choose to wear them occasionally for things like night driving or reading fine detail.

Is the correction permanent?

Laser eye surgery permanently changes the shape of your cornea, which means that the correction doesn’t wear off or reverse over time.

Your vision can still change later in life, but this is usually due to natural ageing inside the eye, such as presbyopia or cataracts, rather than the original treatment.

Find out more about how long laser eye surgery results last and what can change over time.

What happens if laser eye surgery isn’t suitable?

Not everyone is suitable for laser eye surgery, and this usually depends on how the eye is shaped rather than the prescription alone. During your assessment, your consultant will check corneal thickness, the shape of the corneal surface, and whether your prescription has remained stable over time to confirm whether treatment is safe and how predictable the result is likely to be.

If they determine that laser treatment isn’t suitable, there are still other procedure options to explore. 

One option is a toric implantable lens (ICL). Instead of reshaping the cornea, a lens is placed inside the eye that can correct both astigmatism and short- or long-sightedness. This approach is often suitable if the cornea is thin or the prescription is too high for laser treatment.

Another option is lens replacement surgery, where the natural lens of the eye is removed and replaced with an artificial one. This can correct astigmatism as well as short- or long-sightedness, and may be considered when there are early lens changes or when a longer-term solution is needed.

Glasses and contact lenses can still work very well for astigmatism. Toric lenses are made specifically for this type of prescription and are designed to improve focus across the eye without surgery.

Next steps

Laser eye surgery treats astigmatism effectively for most people, but how completely it does so depends on the strength of the prescription and whether the cornea can support the reshaping required. For many people, treatment removes it entirely. For others, a small amount remains, but it doesn’t impact their vision on a daily basis.. Understanding which of those outcomes applies to your eyes is what a proper assessment is for.

At OCL Vision, consultations are led by consultant ophthalmic surgeons who work through your corneal measurements and prescription history before making any recommendations. The outcome you're told to expect is based on your eyes specifically, rather than a general estimate. If you'd like to understand whether laser treatment is suitable and what it's realistically likely to achieve, booking a consultation is the right place to start.