Astigmatism is a sight problem that can affect your ability to see objects at all distances. Mild astigmatism is very common and often does not need to be corrected. It occurs generally when the cornea or clear window into your eye is not a perfectly curved shape. Most people who wear glasses will have some degree of astigmatism. Some case of astigmatism can run in families and it can be corrected with glasses or contact lenses.