Astigmatism is a common and usually minor condition of the eye that causes blurred or distorted vision.
It occurs when the cornea or lens is not a perfectly curved shape. Most people who wear glasses have astigmatism.
If left untreated, astigmatism can also cause:
- eye strain and fatigue (tiredness) – particularly after doing tasks that involve focusing on something for a long period of time, such as reading or using a computer
Why does it happen?
Astigmatism is usually the result of an irregular-shaped cornea or lens.
The cornea is the transparent layer of tissue at the front of the eye. The cornea should be shaped like a football, but in cases of astigmatism it has an irregular curve, more like a rugby ball. This means that light rays entering the eye are not focused properly, creating a blurred image.
In most cases, astigmatism is present at birth. However, it sometimes develops after an injury to the eye or as a complication of an eye operation.
Read more about the causes of astigmatism.
How it is diagnosed
Astigmatism is usually diagnosed after a routine eye test, which often involves testing your ability to focus your eyes.
It is important both for you and and your children to have regular eye tests, as astigmatism can sometimes go undiagnosed for years and it can affect your or your child's ability to read and concentrate.
Read more about diagnosing astigmatism.
In many cases, the symptoms of astigmatism are so mild that no treatment is needed to correct your vision. In cases where your vision is significantly affected by astigmatism, glasses or contact lenses can be used to correct it.
Laser treatment can be used to permanently correct astigmatism in adults. However, it is unlikely you will be able to receive laser treatment through the NHS.
Read more about treating astigmatism.