What Is Astigmatism? Causes, Types, Diagnosis, and Treatment Options

What is Astigmatism?

Astigmatism is a common refractive error of the eye that occurs when the curvature of the cornea or the eye’s internal lens is irregular. This uneven curvature prevents incoming light from being focused precisely onto a single point on the retina.

As a result, vision becomes blurred or distorted at both near and far distances, and this may be accompanied by headaches or eye strain, especially during activities such as reading or prolonged screen use.

In astigmatism, the cornea tends to take on an oval shape, similar to a rugby ball, instead of being evenly round like a basketball. This causes light to be dispersed over multiple focal points rather than one sharp focus.

Astigmatism is a very common condition that can be easily detected through a comprehensive eye examination. It can be effectively corrected with astigmatism‑correcting lenses, such as prescription eyeglasses, toric contact lenses, or other specialty contact lenses designed for astigmatism, all of which help sharpen vision and reduce associated symptoms.

The Difference Between Astigmatism and Nearsightedness/Farsightedness

The key difference between astigmatism and nearsightedness (myopia) or farsightedness (hyperopia) lies in the nature of the visual defect and how it affects eyesight.

In astigmatism, the curvature of the cornea or the lens is irregular, which causes light rays to scatter rather than focus at a single point on the retina. As a result, vision becomes blurred or sometimes appears doubled at all distances.

In myopia, the image focuses in front of the retina, so the person sees nearby objects clearly, while distant objects appear blurred. In hyperopia, the image focuses behind the retina, leading mainly to difficulty seeing near objects, often accompanied by eye strain and discomfort around the eyes.

This difference is reflected in the type of corrective lenses used. Astigmatism is corrected with cylindrical (toric) lenses specifically designed to compensate for the uneven curvature of the cornea, whereas spherical lenses are used to correct myopia and hyperopia.

Understanding the distinction between astigmatism, myopia, and hyperopia helps patients choose the appropriate lenses and achieve more accurate and comfortable visual correction in line with their ophthalmologist’s diagnosis.

How is astigmatism diagnosed?

Astigmatism is diagnosed through a comprehensive eye examination performed by an ophthalmologist or optometrist, using a combination of specialized tests.
The assessment usually starts with a visual acuity test to measure how clearly you can see at distance and near. This is followed by a refraction test—often using an automated or manual refractor—to determine the degree of astigmatism and any associated nearsightedness (myopia) or farsightedness (hyperopia).

In addition, a keratometer or corneal topography is used to map the curvature of the corneal surface in detail and identify irregular areas responsible for blurred or distorted vision.

These advanced tests help detect astigmatism early and accurately determine the appropriate power of corrective lenses for astigmatism—whether cylindrical spectacle lenses or toric contact lenses designed specifically for astigmatism—so the patient can achieve clearer and more comfortable vision.

Accurate diagnosis of astigmatism is an essential step before prescribing any form of corrective lenses, whether standard prescription glasses or specialized medical contact lenses.

Types of Astigmatism

Astigmatism is classified into several main types, which helps the ophthalmologist determine the most suitable corrective lenses for each case.

The most common form is regular astigmatism, where the curvature of the cornea or the lens differs in two principal meridians. This uneven curvature leads to blurred vision at both near and far distances. In such cases, cylindrical lenses or specially designed toric lenses for astigmatism are typically the treatment of choice.

There is also irregular astigmatism, which often develops following corneal trauma, eye surgery, or in conditions such as keratoconus. This type usually requires specialized optical correction, such as rigid gas permeable (RGP) lenses or custom-made lenses designed for advanced astigmatism.

Astigmatism can also be categorized as:

• Simple astigmatism (associated with either myopia or hyperopia),
• Compound astigmatism, and
• Mixed astigmatism, in which myopia and hyperopia coexist in different meridians of the same eye.

Each of these patterns requires precise customization of the eyeglass prescription or contact lenses to achieve clearer vision, while reducing headaches and eye strain.

Understanding the specific type of astigmatism is therefore essential for selecting the most effective lenses and improving both visual quality and overall quality of life.

How does astigmatism affect lens design?

Astigmatism has a direct impact on how corrective lenses are designed. People with mild or severe astigmatism need a specially shaped cylindrical lens to correct the irregular curvature of the cornea or the internal lens of the eye.

The higher the degree of astigmatism, the more precise the calculations must be to determine lens power and axis orientation, so that vision is clear in all directions.

Astigmatic lenses are engineered to distribute optical power unevenly across the lens surface, in a way that compensates for the steeper meridians of the cornea and accurately redirects light to focus on the retina.

This is why we have dedicated options such as astigmatism lenses, toric contact lenses, and high‑precision eyeglass lenses that are custom‑made based on detailed measurements for each eye.

Such specialized designs help reduce blurred vision, ghosting or shadows around objects, and headaches related to visual strain, making the choice of appropriate lenses for astigmatism a key step toward achieving clear and comfortable vision throughout the day.

Do the lenses used vary by type of astigmatism?

Yes. The choice of lenses depends on the type of astigmatism, its severity, and the method of correction—whether with eyeglasses, contact lenses, or intraocular lenses.

Mild astigmatism is usually corrected with cylindrical lenses added to the regular eyeglass prescription. These help sharpen vision and reduce blurring or distortion of letters and lines.

In cases of irregular or high astigmatism, patients are often advised to use special soft toric contact lenses designed for astigmatism, or rigid gas-permeable (RGP) lenses. These provide a more regular optical surface and can significantly improve visual quality.

Implantable intraocular lenses used to correct astigmatism—especially after the age of forty or in the presence of cataracts—are carefully selected based on the type of astigmatism and detailed corneal measurements to achieve precise visual outcomes.

For this reason, a comprehensive eye examination by an ophthalmologist, including measurement of astigmatism with specialized diagnostic devices, is essential to determine the most suitable lens type for each individual case and to achieve the best possible visual clarity.

Tips from Batal Vision Experts for Patients with Astigmatism When Choosing Glasses

The Batal Vision team recommends starting with a comprehensive eye examination to accurately measure the degree and axis of astigmatism, ensuring that your lenses are precisely matched to a reliable medical prescription.

Choose high‑quality lenses specifically designed for astigmatism, such as toric (cylindrical) lenses, and make sure they include anti‑reflective and UV‑protective coatings to reduce visual blur and eye strain.

Verify that the frame suits your face shape and that the lenses are properly aligned with your pupils, as the exact positioning of the lenses in front of the eyes is critical for clear vision in astigmatism.

Batal Vision specialists also advise testing your glasses in the store by looking at different distances to make sure your vision is stable and that you do not experience dizziness or headaches.

Finally, remember to schedule regular eye exams and update your astigmatism prescription when needed. Accurate diagnosis combined with carefully designed astigmatism lenses is the foundation for clear, comfortable vision throughout the day.