What Is Astigmatism?
Astigmatism is a fancy word that is used to describe a malfunction of the way vision works. Astigmatism is a common disorder of the eyes that can cause light to focus on two points instead of just one. This condition can be the result of a misshapen cornea. Astigmatism causes people to have blurry, slanted or distorted vision.
Astigmatism is a refractive error because it affects how the eye refracts, or bends light.
It is a vision disorder in which the eye focuses light on the retina at two points instead of just one. People with astigmatism sometimes complain of blurred, distorted, slanted, or double vision. Astigmatism almost always occurs in both eyes and is usually quite symmetrical between the two. Astigmatism in large amounts is often inherited. Astigmatism can occur in one eye but this is most often due to a traumatic injury.
Causes of Astigmatism
Astigmatism is sometimes caused by an irregularly shaped cornea, the clear dome-like structure on the front part of the eye. The cornea may have areas that are flatter or steeper than others, resulting in distorted vision. The crystalline lens inside the eye may also be tilted slightly, causing astigmatism.
In addition, astigmatism can be caused by an irregular eyelid or heavy tissue pressing down on the eye.
Astigmatism is very common and usually treated or corrected by wearing glasses or contact lenses. Refractive surgery such as LASIK or astigmatic keratectomy can also be helpful in treating astigmatism.
Symptoms of Astigmatism
Astigmatism, if left untreated, can cause distressing vision problems. If you have astigmatism, you may have symptoms that alert you or your healthcare provider. Some symptoms of astigmatism may occur alone, but others might occur together.
If you notice any of the following symptoms, make an appointment with your eye care specialist as soon as possible. (It is generally recommended to have a comprehensive eye exam once per year to ensure the best possible vision as well as prevent or uncover eye disease.)
Blurry or distorted visionEye fatigueEyestrainHeadachesInability to read small printConstant squinting of the eyes
The irregular curvature of the eye leads to blurry or distorted vision for all distances and not just for things close up or far away. Astigmatism can also increase glare around lights at night in a more pronounced way than for those with normal vision. For example, people with astigmatism may say that they see halos or lines from street lights and car lights when driving at night.
Astigmatism is common in children, though they may not complain about blurry or distorted vision. They may struggle in school or even be misdiagnosed as having a learning disability when the issue is really related to their vision. Regular eye exams are a way to detect astigmatism or other vision problems in children and adolescents.
Diagnosing and Treating Astigmatism
Your eye doctor may diagnose astigmatism by conducting a variety of tests. Some of the tests used to diagnose astigmatism include a simple vision test, light refraction test, cornea measurement, or electronically mapping the surface of the eye.
Astigmatism is corrected by focusing light rays on a single plane. This can be accomplished by prescribing eyeglasses or contacts or be performing astigmatic keratotomy.
