A normal cornea — the clear front covering of your eye — has a round curve, like a basketball. However, many people have an irregularly shaped cornea while others have an irregularly curved lens. Both cases can cause light that enters the eye to bend the wrong way, causing blurry vision. This disorder is called astigmatism.

If an abnormally shaped cornea is causing your astigmatism, it’s called corneal astigmatism. Lenticular astigmatism is the term used for astigmatism caused by an irregular lens.

If you have corneal astigmatism, your cornea is shaped more like a football. The curvature of your cornea is probably uneven, with some areas being flatter or steeper than other areas.

Often, astigmatism occurs in conjunction with other vision conditions, such as farsightedness or nearsightedness. All three of these conditions involve errors in the way the cornea and lens refract, or bend light.

Causes

Both children and adults can suffer from astigmatism. In minor cases, they may not even notice a change in vision. While this condition is usually present from birth, it can change over time.

Astigmatism may also develop after eye surgery or an injury. In rare cases, a condition called keratoconus causes astigmatism. This means the cornea becomes thinner and more cone-shaped over time, leading to increasingly poor vision.

Diagnosis

When you get a comprehensive eye exam, your doctor tests for astigmatism. She or he will measure how your eyes focus light. To determine the curvature of your cornea, the doctor uses an instrument called a keratometer. It focuses a circle of light on the cornea. This allows your doctor to measure the reflection and determine the proper fit of contact lenses, if you opt for this treatment option. If your doctor wants even more details, she or he can use a special video camera to map your cornea’s surface. Other instruments measure how your eyes focus light.

Treatment

Wearing eyeglasses is the safest and simplest way to treat astigmatism. Both glasses and contact lenses correct this disorder by altering the way light enters the eyes.

Orthokeratology is a non-invasive procedure involving a series of rigid contact lenses. Worn under your doctor’s careful supervision, you can use these to gradually reshape your corneal curve. However, if you stop wearing these specially designed lenses, your corneas will return to their former shape.

Refractive surgeries, such as LASIK and photorefractive keratectomy (PRK), change your cornea’s shape by using a laser to remove a tiny amount of corneal tissue.

If you suffer from blurry or elongated vision, you might have astigmatism. Call us today so we can schedule an exam and get you on the road to clear vision.

Many correctable vision problems are caused by abnormal eye anatomy. Very few people have perfectly shaped eyes that facilitate ideal vision. Rather, most people have some degree of abnormal curvature or other anatomical irregularities that cause slight visual changes. Astigmatism is one common form of visual impairment that results from irregular anatomy.

What Is Astigmatism?

The clear front area of the eye is called the cornea, which is important for refracting light rays to direct them onto the retinal surface. Light rays pass through the cornea onto the lens. The lens is flexible, changing shape to further focus the light rays and ensure that they hit the retina. Light must bend at a particular angle to result in clear, focused vision. Any abnormalities in eye structure may cause light to be improperly focused onto the retina, preventing visual sensory cells from processing the images.

Astigmatism occurs when either the cornea or the lens is abnormally curved. It is important to note that nearly everyone has some degree of astigmatism, as ocular structures are rarely perfectly shaped. When the cornea or lens has particularly pronounced curvature, however, light rays fail to focus onto the retina. This leads to blurry vision. Unlike farsightedness or nearsightedness, astigmatism causes blurred vision at any distance. Many people have astigmatism as well as farsightedness or nearsightedness.

Diagnosis of Astigmatism

A comprehensive optometry exam checks your eye anatomy and vision for signs of astigmatism. Tests of visual acuity typically reveal some inability to clearly read letters on a distance chart. The eye care provider may also use a keratometer, a tool that measures the curvature of your cornea. By shining a bright light into your cornea and measuring its reflection, the eye doctor can assess the curvature of your cornea. Your eye care provider may also place different lenses in front of your eyes to determine if you have a refractive error and to what extent.

Treatments

Most commonly, treatment for astigmatism consists of prescription eyeglasses or contact lenses. An alternate treatment is orthokeratology, in which your eye doctor provides a series of rigid contact lenses for you to wear for relatively short periods of time. These lenses reshape your cornea, allowing you to have clear vision. Although orthokeratology does not permanently change the shape of your cornea, it may help you go without glasses or contact lenses for everyday activities. Surgery is another option for those who want a more permanent solution.

Astigmatism is very common and relatively easy to treat. If you experience any blurriness or change in vision, consult your eye doctor immediately to receive an optometric exam.