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Home |Glossary|Astigmatism


Astigmatism is a refractive error of the eye where there is a difference in the focusing power of the eye in different meridians.

Astigmatism is typically characterised by an irregular corneal profile where the curvature in one meridian is greater than that of the perpendicular meridian. In a very simple sense the curvature of the cornea can be described as the curvature of a rugby ball which is varied over the surface instead of having a constant radius like the curve of a football (which is a sphere).

Astigmatic Eye Diagram

In regular astigmatism, the meridians in which the two different curves lie are located 180 degrees apart. In irregular astigmatism, the two meridians may be located at something other than 180 degrees apart. Usually astigmatism is hereditary. Some people are born with an oblong cornea, and the resulting vision problem may get worse over time.

Astigmatism may also be the result of an eye injury that has caused scarring on the cornea or from certain types of eye surgery or from keratoconus, a disease that causes a gradual thinning of the cornea.

The result of astigmatism is that objects can appear distorted or blurry at distance and near. The effects of astigmatism can range from mild to severe and cause blurry vision, headaches, squinting or strain on the eyes.

Astigmatic Eye Illustration

Astigmatism can be associated with or without either myopia (short-sightedness) or hyperopia (long-sightedness). It is quite a common condition and in fact the majority of people who need vision correction have some degree of astigmatism.

How do you measure astigmatism?

Astigmatism can be measured from the refraction (spectacle prescription), corneal topography (accurate mapping of the shape of the eye) and wavefront analysis (detailed measurement of visual aberrations).

Can astigmatism be corrected by laser eye treatment?

It surprises us that some patients imagine that because they have astigmatism they cannot have laser eye treatment. This could not be any further from the truth!

AccuVision possess the technology, expertise and experience to correct even very high levels of regular and irregular astigmatism. The laser is used to reshape the corneal surface and create a more smooth corneal profile. This reduces the irregularity in curvature and restores vision.

AccuVision have successfully treated patients with up to 6 Dioptres of astigmatism. Astigmatic correction is incorporated in the laser treatment plan for all patients who require it, to give the best possible outcome for vision.

Is Laser Eye Corrective Surgery Right for You?

At AccuVision your safety and total satisfaction are paramount. Laser eye corrective surgery may not be suitable for everyone and a successful outcome is dependent on many factors which must be carefully considered.

Laser Eye Treatment and Eligibility

Whether or not laser treatment can be performed on your eyes depends on a number of factors that need to be assessed by our eyecare specialists at your initial consultation.

Although the majority of people who come to us are eligible for treatment, due to the high prescription levels we are able to treat, we may decline to treat you if the outcome cannot be accurately predicted or if laser eye surgery treatment is likely to cause complications to your sight. Your lifestyle and occupation may also be an important consideration.

In general, the suitability of our laser eye corrective surgery procedures for you depends on factors such as:

  •  The degree of optical error
  •  The thickness of your cornea
  •  The existence of any eye disease
  •  The size of your pupil
  •  Corneal mapping data
  •  Wavefront analysis results

You should ideally be able to answer YES to the following:

  •  Do you suffer from short-sightedness, long-sightedness or astigmatism?
  •  Are you over 18 years old?
  •  Is your prescription stable?
  •  Are your eyes healthy and free from any eye disease?
  •  Would you rather not wear glasses or contacts on a permanent basis?

Please note that this is only intended as a general guide and there are always exceptions. Detailed analysis of your eligibility for treatment using laser eye corrective surgery can only be achieved at your consultation, but please call us if you wish to discuss the current condition of your eyes and their suitability for treatment on 0330 123 2020.