Astigmatism is a defect in the shape of the cornea of the eye. Usually, the cornea and lense of the eye are smooth and rounded in the same way in all directions so that light can be concentrated on the retina in the back part of the eye. However, if your cornea or lens is not smooth and evenly curved, light rays do not refract properly. This is called a refractive error.
When the cornea has an incorrect shape, the condition is called corneal astigmatism, and when the lens has an irregular shape – lens astigmatism. In both types of astigmatism, eyesight for objects close by and far away is blurred.
People can have congenital astigmatism – actually, most people are probably born with some degree of astigmatism and other refraction abnormalities such as shortsightedness (myopia) or farsightedness (presbyopia). Adults with a higher degree of astigmatism can realize that their eyesight is not as good as it should be, but children who have some astigmatic symptoms may not realize that they have an issue and it is very unlikely that they will complain from blurred or bad eyesight.
The reasons that cause corneal shape to be different in different people is not well understood, but the possibility to develop astigmatism is hereditary.
Sometimes, astigmatism can be developed after eye disease, trauma to the eye or surgery. It is a myth that astigmatism can be developed or made worse by reading in dim light or by sitting close to the TV.
Astigmatic symptoms can include blurred vision or zones of weirdly bent eyesight, tiredness of the eyes and headaches.
Light to medium degrees of astigmatism can be corrected with glasses or contact lenses.
Until recently, astigmatism was mainly treated with hard contact lenses (RGPs, called GP lenses). Nowadays, soft contact lenses, called thoric lenses, can be suitable for some cases of astigmatism, but if you have a severe form of the disease, hard contact lenses or glasses can be a better choise.
In some people with astigmatism, surgery (including laser surgery) can be a good option to correct eyesight.