A quick guide to astigmatism

The outer dome of the eye called the cornea is shaped like a football, with light rays bent uniformly to focus at the back of the eye. Astigmatism occurs when the curvature of the eye’s cornea (or lens) is not spherical: i.e. it’s shaped like a rugby ball. This affects the eye’s ability to focus light on the retina, leading to blurry and distorted vision. This is a minor condition and it can usually be corrected with:

  • Spectacles
  • Contact lenses
  • Surgery

Regular vs. irregular astigmatism

There are two types of astigmatism:

  • Regular: which can be managed by toric lenses
  • Irregular: usually requiring rigid gas permeable contact lenses

Although there are two types of astigmatism, there are three ways that vision can be impaired. These are hyperopic (far sightedness), myopic (near sightedness) and mixed (a combination of near and farsightedness).


What causes astigmatism?

In most cases, an individual is born with an irregularly shaped cornea or, far less commonly, the lens. However, it’s also possible for people to develop this condition later in life. Genetics may play a role and there is no real known way to prevent it from developing. Specific causes include:

  • Eye surgery, such as cataract surgery
  • Eye conditions, such as keratoconus and keratoglobus
  • Conditions that affect the eyelids that push down on the cornea.


Astigmatism symptoms

The symptoms of astigmatism may differ amongst individuals and range from:

  • Asymptomatic
  • Blurry and distorted vision
  • In childhood, if astigmatism isn’t corrected, a lazy eye (amblyopia) can occur.

This blog is contributed by Gurjeet Jutley.