Understanding Astigmatism: A Comprehensive Guide

Astigmatism is a common refractive error. It makes vision appear blurred or distorted at near and far distances. It occurs when the cornea or lens has an uneven curvature. As a result, light does not focus evenly on the retina.

Many people have some degree of astigmatism, and mild astigmatism may not require correction. When it does affect vision, glasses or contact lenses can usually correct it effectively. People who want to wear contact lenses will often use toric lenses, which are specifically designed to correct astigmatism.

What Is Astigmatism?

Astigmatism is a refractive error, like myopia and hyperopia. A normal cornea has an evenly curved surface. An astigmatic cornea may be steeper in one direction.

This uneven curvature changes how light is refracted. Light does not reach a single clear focus on the retina. Instead, different meridians focus light differently. This makes details appear blurred or distorted.

Astigmatism can occur on its own, but it commonly occurs together with short-sightedness or long-sightedness.

What Are the Symptoms of Astigmatism?

The symptoms of astigmatism vary depending on its degree and whether another refractive error is also present. Common symptoms include:

• Blurred or distorted vision at near or far distances
• Difficulty seeing fine details clearly
• Eye strain or tired eyes
• Headaches, particularly after prolonged visual tasks
• Squinting to see more clearly
• Blur or glare that may be more noticeable in low-light conditions

Small amounts of astigmatism may cause few or no noticeable symptoms. This is one reason astigmatism is often discovered during a routine eye examination.

What Causes Astigmatism?

The exact reason some people develop astigmatism is not always known. It often develops early in life, and genetics can play a role.

Astigmatism may be caused by the shape of the cornea or by the lens inside the eye. It can also develop or change after an eye injury, eye surgery or as a result of certain eye conditions.

Keratoconus, for example, is a condition in which the cornea becomes thinner and changes shape. This can cause increasing or irregular astigmatism and requires professional assessment.

Reading in poor light does not cause astigmatism. Working at a computer or phone also does not cause it.

How Is Astigmatism Diagnosed?

An optometrist or ophthalmologist can diagnose astigmatism during an eye examination. Depending on your eyes and symptoms, the examination may include:

• Visual acuity: checking how clearly you can see letters or symbols at different distances.
• Refraction: testing different lens powers to determine which combination provides the clearest vision.
• Keratometry: measuring the curvature of the cornea.
• Corneal topography: creating a more detailed map of the corneal surface when additional information is needed.

Not everyone needs every test. Your optometrist will decide which measurements are appropriate based on your vision and eye health.

Can You Wear Contact Lenses with Astigmatism?

Yes. Many people with astigmatism can wear contact lenses successfully. Soft toric contact lenses are one of the most common options.

Spherical contact lenses primarily correct short- or long-sightedness. Toric contact lenses also provide cylinder correction for astigmatism. These lenses use special designs to maintain a stable orientation on the eye.

If a toric lens rotates, the correction moves from the intended axis. Vision may become temporarily blurred. This is why lens fit and design are important.

What Do CYL and AXIS Mean for Astigmatism?

A toric contact lens prescription normally contains several values:

• SPH or PWR: the spherical power used to correct short- or long-sightedness.
• CYL: the amount of cylinder power needed to correct the astigmatism.
• AXIS: the orientation of the cylinder correction, measured in degrees.

A prescription might, for example, include SPH -3.00 / CYL -1.25 / AXIS 180.

The cylinder and axis values available vary between individual toric lens models. Two products with similar-looking values are therefore not automatically interchangeable. When reordering lenses, use the exact model and parameters that have been fitted or recommended for your eyes.

Which Contact Lenses Are Available for Astigmatism?

Toric contact lenses come in different materials and schedules. Some wearers prefer a fresh pair every day. Others use reusable lenses replaced monthly.

For example, Biofinity Toric is a reusable monthly silicone hydrogel lens. Dailies AquaComfort Plus Toric is a daily disposable option.

Explore our complete range of contact lenses for astigmatism. The best option depends on your prescription and eye shape. Tear film and wearing habits also matter.

Can Astigmatism Be Corrected Without Contact Lenses?

Yes. The main options for correcting astigmatism include:

• Glasses: a straightforward way to correct astigmatism together with short- or long-sightedness.
• Toric contact lenses: soft lenses designed specifically to provide cylinder and axis correction.
• Rigid gas-permeable lenses: another contact lens option that may be suitable for some types of astigmatism.
• Refractive surgery: laser or other procedures may reduce astigmatism in suitable adults after a clinical assessment.

Refractive surgery is not suitable for everyone, and it should not be regarded as a guaranteed permanent cure. Eyes and prescriptions can continue to change over time.

Can Astigmatism Change Over Time?

Yes. Astigmatism can remain relatively stable for many years or change over time. Changes in the cornea, ageing, injury, surgery or certain eye conditions can all affect the prescription.

A rapid change should be assessed by a professional. This is vital if one eye is affected more than the other.

Astigmatism in Children

Astigmatism can occur in children as well as adults. Significant uncorrected astigmatism during childhood can interfere with normal visual development and may contribute to amblyopia, often called lazy eye.

Children may not realize their vision is blurred. This makes eye examinations important. It helps if there are concerns about reading or concentration.

Astigmatism: What to Remember

Astigmatism is common and usually corrected effectively. It happens when the cornea or lens causes uneven light focus. This can result in blurred vision and headaches.

Toric lenses correct astigmatism using spherical power and cylinder correction. Lens design and fit are important. Use the prescription recommended for your eyes.

Explore our toric contact lenses for astigmatism or browse our full range of contact lenses.