Astigmatism is a visual disorder that causes blurred vision due to the irregular shape of the cornea or uneven curvature of the lens inside the eye. The cornea and the lens are responsible for focusing light entering the eyes, allowing images to be clear.
However, an irregularly shaped cornea or lens does not allow the proper focusing of light on the retina, a light-sensitive membrane located at the back of the eye. As a result, vision becomes distorted or blurred.
Astigmatism often occurs with other vision disorders, such as farsightedness and nearsightedness. Collectively, doctors call these vision disorders refractive errors because they affect the manner in which eyes bend or refract light.