Astigmatism

August 18, 1999
Web posted at: 11:41 AM EDT (1541 GMT)

In this story: Description Risk Symptoms Treatment Prevention RELATEDS

From WebMD

DESCRIPTION

Astigmatism is an optical defect that prohibits the eye from focusing sharply, so that images both at a distance and close-up appear fuzzy. One person might not see horizontal images well, while for others, diagonal or vertical lines will be blurred. This condition is most apparent in looking at letters. For instance, the letter G may be perceived as C, and the letter P as F.

The condition is known as a refractory error because it causes a disturbance in the way light is bent, or focused, by the cornea. The normal cornea is shaped like a basketball. But a warped cornea is elongated, like a football, creating two points of focus. If light isn't focused into a single fine point, the image that reaches the retina can't be clearly transmitted to the brain.

Most people have a small degree of astigmatism, and it may not even cause noticeable visual problems. Astigmatism can occur with other eye problems, such as nearsightedness and farsightedness.

RISK

There's no known cause for most cases of astigmatism. However, some people do inherit a genetic form known as keratoconus, which is usually severe enough to require specially shaped contact lenses to enable good vision. In addition, temporary astigmatism can sometimes be caused by corneal scars, surgery, increased pressure of the eyelids on the cornea or doing close-up work.

SYMPTOMS

Distorted or blurred images at all distances is the most common feature of astigmatism. Headaches and eyestrain may also be present as a person squints in an effort to focus.

TREATMENT

In minor cases, treatment isn't necessary. In more severe cases, astigmatism can be treated using contacts or glasses with a toric, or cylinder, lens, which has greater light-bending power in one axis than the other.

New technology is making refractive surgery an option to "cure" astigmatism. There are several types of outpatient surgery available, depending on the degree of astigmatism and any co-existing visual problems:

While these types of surgery are generally safe and effective, complications are possible, including cataracts, persistent pain, infection and even loss of vision. In the worst case, corneal transplant might be required.

PREVENTION

Since most cases of astigmatism are genetic, there is no way to prevent the condition. However, regular eye exams every two years are important. If you develop any sudden visual changes, contact your doctor immediately. And be sure to wear protective eyewear while doing hazardous work and during recreation.

Copyright 1999 WebMD, Inc. All rights reserved.