Astigmatism is one of the most common reasons people need glasses or contact lenses. It occurs when the eye has different focusing power in different directions, causing light to focus unevenly rather than at one clear point. Modern laser refractive procedures can correct many forms of astigmatism. A systematic review comparing wavefront-guided LASIK with SMILE for myopia and astigmatism found that both approaches produced effective visual correction in appropriately selected eyes, although there were differences in some measures of astigmatic accuracy.
What does astigmatism actually mean?
The front surface of the eye, called the cornea, ideally has a smooth and regular curve.
With regular astigmatism, the focusing power differs between different directions of the eye. This can produce blurred or stretched vision at both distance and near.
Some people describe lights as smeared or notice that small text is less clear.
Other possible symptoms include:
- Eye strain
- Headaches
- Difficulty with night driving
- Squinting
- Ghost images
- Blurred vision at several distances
Astigmatism often occurs together with short-sightedness or long-sightedness.
How does laser treatment correct astigmatism?
Laser eye surgery changes the shape of the cornea.
For astigmatism, the treatment pattern is designed to reduce the difference in focusing power between different meridians of the eye.
This requires more than simply knowing the cylinder number on a glasses prescription.
The surgeon may also need to consider the axis of the astigmatism, corneal shape, corneal thickness, optical zone, and whether the astigmatism is regular.
Modern laser planning may use wavefront or corneal topography measurements to personalise treatment in suitable patients.
Can LASIK treat astigmatism?
LASIK can correct many common forms of regular astigmatism.
During the procedure, a thin corneal flap is created. The excimer laser then reshapes the corneal tissue underneath according to the planned prescription.
AccuVision states that it offers customised laser treatments for astigmatism and considers the amount and type of astigmatism together with other measurements of the eye.
However, the question is not simply whether a certain cylinder number can technically be programmed into a laser.
The more important question is whether performing that correction is suitable for the particular cornea.
What if the astigmatism is high?
Higher astigmatism may require more detailed evaluation.
The surgeon should confirm whether the astigmatism is stable and whether it comes mainly from the front of the cornea, another structure in the eye, or an irregular corneal condition.
A high or rapidly changing astigmatism may occasionally be a sign of keratoconus or another corneal disorder.
In that situation, ordinary refractive laser treatment may not be appropriate.
Corneal topography and tomography are therefore important when unusual astigmatism is present.
What is irregular astigmatism?
Regular astigmatism usually follows an organised optical pattern that can often be corrected well with spectacles.
Irregular astigmatism has a more complex shape. It may result from keratoconus, corneal scars, previous surgery, trauma, or another condition.
Special contact lenses may sometimes provide better vision than ordinary glasses in these cases.
Selected patients may be candidates for highly customised corneal treatment, but this requires specialist assessment. Treatment should not be promised simply because a laser platform is capable of complex programming.
What about night vision?
Astigmatism itself can make night vision more difficult.
Patients may notice halos, starbursts, glare, or elongated lights.
Laser correction can reduce prescription-related blur, but refractive surgery can also cause temporary or persistent night-vision symptoms in some patients.
Pupil size, treatment zone, original prescription, tear quality, and corneal optics may influence the result.
Anyone who regularly drives at night should discuss this specifically during the consultation.
How important is dry eye?
Very important.
A poor tear film can make both vision and corneal measurements fluctuate.
Someone whose astigmatism appears to change between repeated tests may sometimes have an unstable eye surface.
Dry eye or eyelid inflammation may therefore need treatment before final laser measurements are taken.
Are results permanent?
The corneal change produced by laser treatment is intended to be long-lasting.
However, eyes continue to age.
The prescription may change naturally over the years. Presbyopia can develop after the age of about 40, and cataracts may develop later in life.
Laser treatment cannot stop these normal biological changes.
Who should have a detailed assessment?
Assessment is particularly important when:
- The astigmatism is high
- The prescription has recently changed
- Vision is poor even with new glasses
- One eye is very different from the other
- There is a family history of keratoconus
- The person rubs their eyes frequently
- Previous laser surgery has been performed
- Night vision is a major concern
- The person has significant dry eye
People interested in treatment can review AccuVision’s information on laser vision correction for astigmatism. Its current treatment information states that glasses, contact lenses, and laser surgery are among the possible approaches, with suitability dependent on the individual eye.
Questions to ask before treatment
Ask:
This article is intended for general education and does not replace individual examination or treatment planning by an ophthalmic professional.