What is Astigmatism and Can It Be Treated? | Blue Planet Optics

Astigmatism is a common condition in which the eye can’t focus light evenly onto the retina, causing blurred or distorted vision. It occurs due to an irregular curvature of the cornea or lens. This uneven shape causes light to refract incorrectly, which results in vision problems at various distances.

The good news is that astigmatism can be treated through several methods, with eyeglasses, contact lenses, and surgery being the most common three.

What Does It Mean to Have Astigmatism?

Think of the cornea as a round ball. In a healthy eye, it’s smooth with a round surface, letting light focus correctly onto the retina.

However, in an astigmatic eye, the cornea is shaped more like a football, causing light to focus on multiple points, either in front of or behind the retina. This distortion leads to blurred vision and difficulty seeing fine details. So:

• Healthy cornea – It is smooth and evenly curved. The light focuses directly on the retina.
• Astigmatic cornea – The cornea has an irregular, oval shape, which makes light to focus on multiple points within the eye, instead of one. In this case, images appear blurry or stretched out.

Types of Astigmatism

The difference between a normal cornea and an astigmatic one lies in the curvature asymmetry that prevents light from focusing properly. However, astigmatism can actually be divided into two main types, both of which lead to distorted vision.

Corneal Astigmatism

Corneal astigmatism is the most common form. It occurs when the cornea — the clear front surface of the eye — is irregularly shaped and has a more asymmetrical form. This causes light to refract in different directions, which leads to multiple focal points on the retina rather than one clear point, resulting in blurred or distorted vision at various distances.

Lenticular Astigmatism

Lenticular astigmatism results from an irregular shape of the lens inside the eye, hence it’s a less common type of astigmatism. The lens sits behind the pupil and adjusts its shape to focus light at different distances. When the lens is not symmetrical, it distorts light refraction, causing similar visual disturbances as corneal astigmatism, even though the cornea may be perfectly normal.

With-the-Rule vs. Against-the-Rule Astigmatism

Astigmatism is also classified based on the direction of the irregular curvature.

With-the-rule Astigmatism

In this case, the cornea or lens has a steeper curvature along the vertical axis and the eye is more curved from top to bottom than from side to side. This makes the vertical meridian (the 90-degree axis) of the cornea refract light more strongly than the horizontal meridian. 

People with this type of astigmatism usually experience a horizontal blur or distortion of images. With-the-rule astigmatism is more common among younger individuals because their corneas tend to be naturally steeper along the vertical axis.

Against-the-rule Astigmatism 

Against-the-rule astigmatism occurs when the steepest curvature is along the horizontal axis of the cornea, making the eye more curved from side to side than from top to bottom. Here, the horizontal meridian (the 180-degree axis) is the strongest, which can cause vertical lines to appear blurry or distorted. 

People with this type of astigmatism may find it hard to focus on vertical lines, leading to vertical blur in their vision. This type of astigmatism is more common in older individuals, as the cornea tends to flatten over time along the vertical axis, shifting the steepest curve to the horizontal plane.

Astigmatism Symptoms

Individuals with astigmatism may experience a wide range of symptoms:

• Blurred or distorted vision at all distances.
• Eye strain, discomfort, and headaches, especially after prolonged focus, such as reading or working at a computer.
• Difficulty seeing at night clearly.
• In more severe cases, astigmatism causes dizziness or a feeling of unsteadiness.

These symptoms of astigmatism appear because the eyes are constantly trying to adjust to the distorted images they are receiving.

What Causes Astigmatism to Worsen?

In addition to being hereditary, several other factors can cause or worsen astigmatism:

• Eye injuries can cause scarring or reshaping of the cornea resulting in astigmatism. 
• Surgical procedures, particularly on the cornea, may alter the eye’s natural structure.
• Keratoconus is a degenerative condition that causes the cornea to gradually thin and take on a cone shape. It often results in more severe forms of astigmatism.
• Aging is another common cause. As we grow older, we may develop astigmatism or see it worsening due to the natural change in the cornea’s shape.

How Do You Test for Astigmatism?

Diagnosing astigmatism is a simple process that can be done during routine eye exams. Your eye doctor will do various tests to detect astigmatism:

Visual Acuity Test

This test can measure your ability to see letters at different distances, on a Snellen chart — that’s the familiar chart with rows of letters of decreasing size. If you struggle to distinguish between them, it may indicate a refractive error like astigmatism.

Keratometry

Keratometry measures the curvature of the cornea. A keratometer shines a circle of light on the cornea; the reflection is measured to assess its curvature. 

Since astigmatism is caused by an uneven curvature, this test quantifies the degree and orientation of the corneal irregularity. Besides being a key tool when diagnosing corneal astigmatism, keratometry is also useful when fitting contact lenses, as it determines the proper lens shape.

Corneal Topography

Corneal topography maps the cornea’s surface to allow ophthalmologists to detect irregularities. It uses a special camera that takes multiple images of the cornea to create a three-dimensional map that shows any areas of steeper or flatter curvature. 

Corneal topography can diagnose more severe or irregular cases of astigmatism and conditions like keratoconus, where the cornea becomes progressively thinner and cone-shaped.

Refraction Test

A refraction test determines the precise prescription needed to correct your vision. For this test, the opthalmologist uses a phoropter — that’s the machine with multiple lenses — to determine the ideal corrective lens prescription. 

You look through different lenses and identify which ones make the letters on the chart clearer. The doctor then measures how your eyes focus light and uses this data to pinpoint astigmatism and other potential refractive errors such as myopia (nearsightedness) or hyperopia (farsightedness). 

Can Astigmatism Be Corrected?

Astigmatism can be corrected through various treatment options, depending on its severity and the patient’s preference.

Eyeglasses

Eyeglasses are the most common and non-invasive treatment. Glasses with cylindrical lenses correct the uneven curvature of the cornea or lens. These lenses help focus light properly on the retina, improving vision.

Contact Lenses

For those who prefer contact lenses rather than glasses, toric contact lenses are available for people with astigmatism. They offer multiple powers to correct the irregular shape of the cornea and come in both soft and rigid forms, with some options tailored to more severe cases.

If you want to learn more about contact lens options, Blue Planet Optics offers a wide collection of lenses for astigmatism.

Orthokeratology (Ortho-K)

Many people who suffer from more severe astigmatism often try Orthokeratology (Ortho-K), as it’s a non-surgical solution. This treatment requires wearing rigid contact lenses overnight to reshape the cornea temporarily. When worn during sleep, these lenses correct the cornea’s curvature to provide clear vision throughout the day, without the need for glasses or contacts.

Laser Surgery

If interested in a more permanent solution, a laser surgery like LASIK or PRK can reshape the cornea, so that it allows light to focus correctly on the retina. These procedures are particularly effective for moderate to severe astigmatism and can improve vision without the need for corrective lenses.

What Happens if Astigmatism Is Left Untreated?

If untreated, astigmatism can significantly impact a person’s daily life. The constant effort to focus on distorted images can lead to persistent headaches, eye fatigue, and difficulty performing activities that require prolonged concentration, such as reading or working on a computer. In severe cases, it can cause dizziness and affect balance​.

Ask Your Ophthalmologist

Astigmatism is a treatable eye condition. From eyeglasses and contact lenses to surgical options, individuals have several methods to correct their vision.

If you suspect you have astigmatism, or notice your symptoms worsen, you’d better schedule an eye check-up with your ophthalmologist for a thorough examination and personalized treatment plan.

If you don’t know where to start and need more information on contact lenses for astigmatism, visit the Blue Planet Optics blog.

Frequently Asked Questions

Can astigmatism cause dizziness?

Moderate to severe astigmatism can cause dizziness, nausea, and headaches, especially if left untreated. This is due to constant strain on the eyes as they try to correct the blurry vision. If you experience these symptoms frequently, see an eye doctor for a comprehensive eye exam, proper diagnosis, treatment, and overall eye health.

What is the main cause of astigmatism?

The main cause of astigmatism is the irregular shape of the cornea or lens, which can be inherited or developed over time. An eye injury or eye surgery could also contribute to its development, as can conditions like keratoconus or aging.

What happens if you have astigmatism?

If you have astigmatism, your vision will be blurry or distorted at all distances, and you may have headaches or eye strain. In more severe cases, you may also feel dizzy or struggle focusing, especially at night.

How does a person with astigmatism see?

A person with astigmatism may see objects as blurry or stretched, with straight lines appearing wavy or crooked. These distortions can make it difficult to focus on fine details, both up close and at a distance.

Can you fix astigmatism? 

Astigmatism is a treatable eye condition that affects millions of people globally. The right treatment, such as glasses, contact lenses, or surgery, can bring clear vision and reduce the discomfort linked with this condition.

Can astigmatism change over time?

Υes, astigmatism can change over time, either worsening or improving. Age-related changes in the cornea can lead to shifts in the type of astigmatism (for example, from with-the-rule to against-the-rule) due to the natural flattening of the vertical meridian as people age. You need regular eye check-ups to monitor these changes and adjust vision correction if necessary.

How does astigmatism affect children, and when should it be corrected? 

In children, astigmatism can lead to more serious vision problems like amblyopia (lazy eye) if left untreated. That’s why early detection is so important, as it guarantees normal visual development and prevents learning difficulties. 

What causes astigmatism?

Astigmatism is often genetic, which means that you can inherit the condition, and be born with it. In these cases, the shape of the cornea or lens is naturally irregular.

What is against-the-rule astigmatism?

In against-the-rule astigmatism, the steepest curvature is along the horizontal axis of the cornea, making the eye more curved from side to side than from top to bottom. This causes the horizontal meridian to be the strongest, which can lead to vertical lines appearing blurry or distorted. People with this type of astigmatism may find it hard to focus on vertical lines, resulting in vertical blur in their vision. Against-the-rule astigmatism is more common in older individuals, as the cornea tends to flatten over time along the vertical axis, shifting the steepest curve to the horizontal plane.

What is astigmatism?

Astigmatism is a common condition in which the eye can't focus light evenly onto the retina, causing blurred or distorted vision.

How is astigmatism diagnosed?

Diagnosing astigmatism is a simple process that can be done during routine eye exams. Your eye doctor will do various tests to detect astigmatism, including:

Visual Acuity Test: This test can measure your ability to see letters at different distances, on a Snellen chart. If you struggle to distinguish between them, it may indicate a refractive error like astigmatism.

Keratometry: Keratometry measures the curvature of the cornea. A keratometer shines a circle of light on the cornea; the reflection is measured to assess its curvature. Since astigmatism is caused by an uneven curvature, this test quantifies the degree and orientation of the corneal irregularity. Besides being a key tool when diagnosing corneal astigmatism, keratometry is also useful when fitting contact lenses, as it determines the proper lens shape.

What is with-the-rule astigmatism?

In with-the-rule astigmatism, the cornea or lens has a steeper curvature along the vertical axis, making the eye more curved from top to bottom than from side to side. This causes the vertical meridian of the cornea to refract light more strongly than the horizontal meridian, leading to a horizontal blur or distortion of images. With-the-rule astigmatism is more common among younger individuals because their corneas tend to be naturally steeper along the vertical axis.

What is a healthy cornea like?

In a healthy eye, the cornea is smooth and evenly curved, allowing light to focus directly on the retina.

How can I correct my vision if I have astigmatism?

Individuals have several methods to correct their vision, such as eyeglasses, contact lenses, orthokeratology, and laser surgery.

What are the common symptoms of astigmatism?

Individuals with astigmatism may experience a wide range of symptoms, including blurred or distorted vision at all distances, eye strain, discomfort, and headaches, especially after prolonged focus, such as reading or working at a computer, difficulty seeing at night clearly, and in more severe cases, dizziness or a feeling of unsteadiness.

What can cause astigmatism or make it worse?

According to the information provided, several factors can cause or worsen astigmatism:

• Eye injuries can cause scarring or reshaping of the cornea, resulting in astigmatism.
• Surgical procedures, particularly on the cornea, may alter the eye's natural structure.
• Keratoconus, a degenerative condition that causes the cornea to gradually thin and take on a cone shape, often results in more severe forms of astigmatism.
• Aging is another common cause, as the natural change in the cornea's shape over time can lead to the development or worsening of astigmatism.

What equipment is used during a refraction test?

For this test, the ophthalmologist uses a phoropter — that's the machine with multiple lenses — to determine the ideal corrective lens prescription.

What is corneal astigmatism?

Corneal astigmatism is the most common form of astigmatism. It occurs when the cornea, the clear front surface of the eye, is irregularly shaped and has a more asymmetrical form. This causes light to refract in different directions, leading to multiple focal points on the retina rather than one clear point, resulting in blurred or distorted vision at various distances.

How does corneal topography work?

Corneal topography uses a special camera that takes multiple images of the cornea to create a three-dimensional map that shows any areas of steeper or flatter curvature.

How does the doctor use the results of a refraction test?

The doctor then measures how your eyes focus light and uses this data to pinpoint astigmatism and other potential refractive errors such as myopia (nearsightedness) or hyperopia (farsightedness).

What are the two main classifications of astigmatism based on the direction of the irregular curvature?

Astigmatism is classified as either with-the-rule astigmatism or against-the-rule astigmatism, based on the direction of the irregular curvature.

What are the common treatments for astigmatism?

Astigmatism can be corrected through various treatment options, including:

• Eyeglasses with cylindrical lenses to correct the uneven curvature of the cornea or lens
• Toric contact lenses that offer multiple powers to correct the irregular shape of the cornea
• Orthokeratology (Ortho-K), a non-surgical treatment that uses rigid contact lenses worn overnight to temporarily reshape the cornea
• Laser surgery like LASIK or PRK to permanently reshape the cornea and improve vision without the need for corrective lenses

What is the purpose of a refraction test?

A refraction test determines the precise prescription needed to correct your vision.

What are the consequences of untreated astigmatism?

If untreated, astigmatism can significantly impact a person's daily life. The constant effort to focus on distorted images can lead to persistent headaches, eye fatigue, and difficulty performing activities that require prolonged concentration, such as reading or working on a computer. In severe cases, it can cause dizziness and affect balance.

What eye conditions can corneal topography diagnose?

Corneal topography can diagnose more severe or irregular cases of astigmatism and conditions like keratoconus, where the cornea becomes progressively thinner and cone-shaped.

What should I do if I suspect I have astigmatism or notice my symptoms worsen?

If you suspect you have astigmatism, or notice your symptoms worsen, you should schedule an eye check-up with your ophthalmologist for a thorough examination and personalized treatment plan.

What are the two main types of astigmatism?

Astigmatism can be divided into two main types: corneal astigmatism and lenticular astigmatism.

What is lenticular astigmatism?

Lenticular astigmatism results from an irregular shape of the lens inside the eye, making it a less common type of astigmatism. When the lens is not symmetrical, it distorts light refraction, causing similar visual disturbances as corneal astigmatism, even though the cornea may be perfectly normal.