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.
Cholappadi SundarRaj, OD, PhD, optometrist, UPMC Eye Center, explains what causes astigmatism and how your eye doctor may treat it.
What is Astigmatism?
Astigmatism 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.
On 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.
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Symptoms of Astigmatism
Common symptoms of astigmatism are:
- Distorted vision or blurred vision
- Eye discomfort
What Are the Types of Astigmatism?
The two main types of astigmatisms are lenticular and corneal. They are often referred to as irregular or regular.
Lenticular astigmatisms are a result of distortion in the lens. Corneal astigmatisms are caused by distortion in the cornea.
How is Astigmatism Diagnosed?
Astigmatism 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.
How is Astigmatism Treated?
Astigmatism, if present in combination with nearsightedness (myopia), far sightedness (hypermetropia), or on its own, can be corrected by:
- soft contact lenses
- Specialty lenses
In adults where the refractive error has stabilized with age, refractive or laser vision correction surgery is a popular way to permanently correct vision. In some cases, surgery is offered to alter the shape of the cornea to properly focus on light.
Editor's Note: This article was originally published on , and was last reviewed on .
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