Astigmatism is caused by a cornea shaped like a “football,” meaning it is more curved in one direction and flatter in the opposite direction. This results in two different focal points in the eye, either in front of or behind the retina. People with astigmatism may also see distorted images, especially toward the periphery of their vision. In most cases, astigmatism is combined with another refractive error such as myopia or hyperopia.

After myopia, astigmatism is the most common vision disorder.

Signs and symptoms of astigmatism

For people with astigmatism, blurry vision at both near and far distances is often associated with headaches. Those with mild astigmatism may not realize they have it until they undergo an eye exam with an optometrist. People with moderate astigmatism see blurred lines and outlines of objects. In addition, image distortion can make it difficult to distinguish between similar characters.

Sometimes, a person with astigmatism who strains their eyes for long hours may also tend to squint due to fatigue.