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Astigmatism

What is the condition?

Astigmatism is an eye condition that is often misunderstood. It is not an eye disease, but more of a problem related to how your eyes focus light.  It is a refractive error (eye prescription) that occurs due to the eye not being completely round.  The cornea or lens is supposed to have a spherical curvature but with astigmatism, either could have an oval or football shaped curvature causing distorted images.


How does it affect the eye?

A common visual problem, astigmatism causes vision to become blurry or distorted at any distance. This is because light rays that fall on the retina are prevented from meeting at a common focal point due to the imperfect curvature of the cornea or lens.

 

How many types of astigmatism are there?

Astigmatism can be classified as regular or irregular.  In regular astigmatism, the principal meridians are perpendicular to one other, while in irregular astigmatism, they are not perpendicular to each other.  Irregular astigmatism could result from certain types of eye surgeries, corneal diseases such as keratoconus or pterygium, or from eye injuries that have left scarring on the cornea.
Other than regular and irregular astigmatism, there are three other types of astigmatism:

  • Hyperopic astigmatism: This occurs when one or both of the principal meridians of the eyes are farsighted.
  • Myopic astigmatism: This occurs when one or both of the principal meridians of the eyes are nearsighted.
  • Mixed astigmatism: This occurs when one principal meridian is nearsighted, while the other is farsighted.


What are the symptoms of this condition?

Some symptoms of astigmatism are:

  • Irritation or discomfort of the eye; Eyestrain
  • Blurry or distorted images at any distance
  • Squinting
  • Headaches
  • Difficulty with night vision


What are the risk factors for developing this condition?
Some of the risk factors include:

  • Astigmatism can be associated with certain eye diseases, such as keratoconus.
  • Astigmatism is hereditary.
  • If you have had any eye surgery, such as a cataract removal, you may have a higher chance of having astigmatism.

 

How is this condition treated?

There are a few ways to treat astigmatism, such as:

  • Refractive surgery: With the help of laser or refractive surgery, you can change the shape of your cornea. However, this method is recommended only to patients that are free from any other kinds of eye issues.
  • Contact lenses or eye glasses: Your optometrist can prescribe you glasses or contact lenses that correct your astigmatism. Contacts that correct astigmatism are called Toric lenses, they are weighted to always fall in the same position on your eye.