Astigmatism Explained


What is Astigmatism?

The term Astigmatism is used when either the ‘Cornea’ (clear membrane at the very front of the eye) or the ‘Lens’ (oval shaped focusing structure just behind the pupil), is shaped like a rugby ball, being more curved in one direction than another. Approximately 90% of individuals have some degree of astigmatism. However as most occurrences are minor, it can often be corrected by adjusting existing prescriptions for long or shortsightedness.

For someone with a substantial level of astigmatism, it means that objects at some orientations will be more defined and in focus than objects at different orientations. The overall effect is a general blur to the individual, depending on their level of defect.

Although astigmatism can develop from eye injury, surgery or eye disease, almost all cases exist from birth. Its direct cause is not well understood, though there is a strong genetic link and correction is required early in life to prevent astigmatic Amblyopia (lazy eye).

Your optician will advise you on the best means of correction, be it spectacles, soft ‘toric’ or the smaller rigid (RGP) contact lenses. The lenses used to correct astigmatism have two different curves at right angles to each other, where the degree of curve and orientation is very patient specific. Laser surgery can also be sometimes used.