What Is Astigmatism? Causes, Symptoms & Treatment

Blurry vision does not always mean your prescription is simply too weak. Sometimes, the issue comes from the shape of the eye itself. That is what happens with astigmatism.

Astigmatism is a common vision condition that can make objects look blurry, stretched, shadowed, or distorted. It can affect how you see up close, far away, or both. Some people have very mild astigmatism and barely notice it. Others may deal with headaches, eye strain, squinting, or trouble seeing clearly at night.

The good news is that astigmatism is usually easy to manage. Eyeglasses, contact lenses, and certain vision correction procedures can help sharpen vision and reduce discomfort.

What Is Astigmatism?

Astigmatism is a type of refractive error. A refractive error happens when the eye does not bend light properly onto the retina, which is the light-sensitive tissue at the back of the eye.

For clear vision, light needs to focus sharply on the retina. The cornea, which is the clear front surface of the eye, and the lens inside the eye both help with this focusing process.

In an eye without astigmatism, the cornea and lens are usually curved more evenly. In an eye with astigmatism, the cornea or lens has an uneven curve. Instead of being shaped more like a round basketball, it may curve more like a football or the back of a spoon.

What Causes Astigmatism?

Astigmatism is usually linked to the natural shape of the eye. Some people are born with it, while others develop it later.

Common causes and related factors include:

• A naturally uneven cornea
• An uneven curve in the lens inside the eye
• Family history of astigmatism
• Eye injury
• Eye surgery
• Scarring on the cornea
• Keratoconus, a condition that causes the cornea to thin and bulge outward

Astigmatism is not caused by reading in dim light, sitting too close to the television, or spending long hours on a computer. Those habits can make your eyes feel tired, but they do not change the shape of your cornea or lens.

How Astigmatism Affects Vision

Astigmatism can affect vision in different ways. Some people notice that words look slightly blurred when reading. Others may see streaks around lights, especially while driving at night.

Astigmatism can also make vision feel inconsistent. You may see fairly well in one situation but struggle in another, especially when your eyes are tired or lighting is poor.

This happens because the eye has different curvatures in different directions. Eye doctors often describe these directions as meridians. When one meridian is steeper or flatter than another, the eye focuses light unevenly.

That uneven focus is what causes the blur or distortion.

Types Of Astigmatism

Astigmatism can occur on its own, but it often appears with nearsightedness or farsightedness.

Myopic Astigmatism

Myopic astigmatism happens when astigmatism occurs with nearsightedness. This means distant objects may look blurry, while nearby objects may appear clearer.

Hyperopic Astigmatism

Hyperopic astigmatism happens when astigmatism occurs with farsightedness. This can make near vision harder, although distance vision may also be affected.

Mixed Astigmatism

Mixed astigmatism means one part of the eye focuses light in front of the retina, while another part focuses light behind it. This can make both near and distance vision blurry.

You do not need to memorize the type you have. Your eye doctor will measure your prescription and explain which correction is right for your eyes.

How Common Is Astigmatism?

Most people have some degree of astigmatism, but it is frequently so mild that no corrective lenses are needed. It has been reported that an estimated 40% of people who wear corrective lenses (eyeglasses or contact lenses) have astigmatism.

What Are the Symptoms of Astigmatism?

Mild astigmatism may produce no symptoms. With moderate or severe astigmatism the following symptoms may occur:

• Headaches
• Eyestrain or fatigue
• Squinting
• Blurred vision at all distances
• Holding reading material closer than normal

Who Is at Risk?

Anyone can have astigmatism. A family history of astigmatism is an added risk factor.

How Is Astigmatism Detected?

Astigmatism is detected by a comprehensive eye exam performed by an optometrist or ophthalmologist. Children with mild or moderate astigmatism can sometimes pass a school vision screening. Therefore, all preschoolers should have a thorough eye exam to evaluate their vision and rule out the presence of astigmatism.

How Is Astigmatism Treated?

Astigmatism can usually be corrected with eyeglasses, contact lenses, or refractive surgery. The right treatment depends on your prescription, eye health, comfort, lifestyle, and your eye doctor’s recommendation.

Eyeglasses

Eyeglasses are one of the simplest ways to correct astigmatism. The lenses are made with a prescription that balances the uneven focus caused by the shape of the cornea or lens.

Glasses can be a good option for children, first-time correction, or people who prefer a low-maintenance way to see clearly.

Contact Lenses

Contact lenses are another option for correcting astigmatism. In most cases, eye doctors prescribe toric contact lenses, which are soft lenses made specifically for people with astigmatism.

Toric lenses have different powers across the lens to help correct the uneven focus caused by astigmatism. They also need to stay in the right position on the eye, so a proper contact lens fitting is important for clear, stable vision.

Depending on your prescription and eye shape, your eye doctor may also recommend rigid gas permeable lenses, hybrid lenses, or scleral lenses.

Once you have a valid prescription, you can order toric contact lenses online at 1-800-GET-LENS.

Refractive Surgery

Some adults with stable prescriptions may be candidates for refractive surgery, such as LASIK or PRK. These procedures reshape the cornea so light focuses more clearly on the retina.

Refractive surgery is not suitable for everyone. Your eye doctor will need to check your prescription stability, corneal thickness, tear health, and overall eye condition before recommending it.

Final Thoughts

Astigmatism is a common vision condition caused by an uneven curve in the cornea or lens. It can make vision blurry or distorted, but it is usually manageable with the right correction.

Glasses, contact lenses for astigmatism, and refractive surgery can all help people with astigmatism see more clearly. The best way to know what you need is to schedule a full eye exam with an eye care professional.

This article is for informational purposes only and does not replace professional medical advice. Always consult an eye care professional for diagnosis and treatment.