What is astigmatism?

Astigmatism is a common eyesight problem. It causes a blurred image which can be corrected in most cases. Here is how it works.


The condition is caused by a not perfectly curved cornea, the transparent layer of tissue at the front of your eye. This irregular curve means that light rays entering your eye focus in two different places on the light-sensitive tissue (retina) at the back of your eye. The brain has difficulties interpreting this hence a blurred image is created. This eye condition is usually present at birth and may accompany other vision problems such as nearsightedness and farsightedness.


Except for blurred or distorted vision up close and at a distance, you might also have these signs of astigmatism:


  • Trouble distinguishing between vertical, horizontal and oblique shapes
  • Confusing letters such as H for N or C for O
  • Headaches and eye strain
  • Injuries to the cornea, such as an infection that scars the cornea
  • Changes to the cornea caused by eye surgery
  • Keratoconus and keratoglobus – eye conditions that cause the cornea to bulge, get thinner and change shape
  • Some conditions that affect the eyelids and distort the cornea
  • Other conditions that affect the cornea or lens


Usually, astigmatism can be corrected effectively with toric lenses. These are specially designed and shaped to compensate for the irregular curve of the cornea that causes astigmatism. If you are concerned about your vision or notice that it has changed, contact your nearest optician.