Astigmatism is a common refractive eye condition that occurs when the cornea of the eye has an irregular shape, rather than being perfectly spherical. This irregularity causes light to be focused on multiple points within the eye, instead of a single point on the retina, leading to distorted or blurred vision. In an eye with astigmatism, the cornea or lens may be more curved in one direction than in another, like the shape of a football rather than a basketball. As a result, the eye may have different focal points for vertical and horizontal lines, causing images to appear stretched, skewed, or out of focus.
Astigmatism can occur alongside other refractive errors, such as short sightedness (myopia) or far sightedness (hyperopia). People with astigmatism may experience a variety of vision problems, including difficulty seeing fine details, glare, and problems with night vision.