A refractive error is when the shape of your eye prevents light rays from properly coming together on the retina and cause images to blur. Astigmatisms are one type of refractive error and the one of the most common reason why a person goes to see an eye doctor.\nCholappadi SundarRaj, OD, PhD, optometrist, UPMC Eye Center, explains what causes astigmatism and how your eye doctor may treat it.\nWhat is Astigmatism?\nAstigmatism is a refractive error that causes blurred or distorted vision. When light enters the eye through the pupil, it refracts or bends as it goes through the natural lens behind the iris and focuses on the retina, called fovea.\nOn average, normal eyes are shaped like a sphere. However, the eye of a person with astigmatism is shaped like a football (oval) and the light travelling through the natural lens is bent in more than one direction allowing only a part of the object to focus on the retina. The other part focuses in front or behind the retina.\nHow do I Know if I Have One?\nUndetected astigmatisms cause symptoms such as blurred vision and eye strain, especially after a long day in front of a computer. Sometimes, this may also cause headaches. You\u2019ll need to visit an eye doctor for the diagnosis and treatment of astigmatism.\nHow is Astigmatism Diagnosed?\nAstigmatism is a common diagnosis. It is detected in most of the routine eye examinations by instruments that can diagnose, measure the degree (axis) of the curvature, and the amount of Astigmatism in the cornea or back of the eye.\nHow is Astigmatism treated?\nAstigmatism, if present in combination with nearsightedness (myopia), far sightedness (hypermetropia), or on its own, can be corrected by glasses, soft contact lenses, or specialty lenses if the astigmatism exceeds a certain level. In adults where the refractive error has stabilized with age, refractive or laser vision correction surgery is a popular way to permanently correct vision.