Overview

Astigmatism is one of the most common vision conditions, affecting approximately one in three people worldwide. This refractive error occurs when the cornea (the clear front surface of the eye) or the lens inside the eye has mismatched curves. Instead of having one curve like a round ball, the surface is egg-shaped, with one curve being significantly different than the other.

This irregular shape prevents light from focusing properly on the retina, the light-sensitive tissue at the back of the eye. As a result, vision becomes blurred or distorted at all distances. Astigmatism can occur on its own or alongside other refractive errors such as myopia (nearsightedness) or hyperopia (farsightedness).

The condition can be present from birth or develop gradually over time. While astigmatism can cause significant visual discomfort and interfere with daily activities, it is highly treatable with various corrective options ranging from eyeglasses to surgical procedures.

Symptoms of Astigmatism

The symptoms of astigmatism can vary depending on the severity of the condition. Some people with mild astigmatism may not notice any symptoms, while others with more significant astigmatism may experience multiple visual disturbances. Understanding these symptoms is crucial for early detection and treatment.

Common Symptoms

  • Diminished vision - Blurred or distorted vision at all distances, making it difficult to see fine details clearly
  • Double vision - Seeing duplicate images, particularly when looking at lights or bright objects
  • Eye pain - Discomfort or aching in and around the eyes, especially after prolonged visual tasks
  • Eye strain - Fatigue and tension in the eyes after reading, using computers, or other close work
  • Spots or clouds in vision - Visual disturbances that can appear as shadows or unclear areas in the field of vision
  • Foreign body sensation in eye - Feeling as if something is in the eye, often accompanied by irritation
  • Lacrimation - Excessive tearing or watery eyes, particularly in bright light or during visual tasks
  • Eye deviation - Misalignment of the eyes, which may occur as the visual system attempts to compensate for the refractive error

Less Common Symptoms

  • Headaches - Frequent headaches, particularly after visual tasks or at the end of the day
  • Squinting - Habitually narrowing the eyes to try to see more clearly
  • Night vision problems - Difficulty seeing clearly in low light conditions, with increased glare and halos around lights
  • Light sensitivity - Discomfort or pain when exposed to bright lights

The severity and combination of symptoms often depend on the degree of astigmatism and whether it occurs with other refractive errors. Children with astigmatism may not complain of visual problems but might exhibit behaviors such as tilting their head, closing one eye, or sitting very close to the television.

Causes of Astigmatism

Astigmatism occurs when the cornea or lens has an irregular curvature, preventing light from focusing properly on the retina. Understanding the various causes can help in prevention and management of the condition.

Primary Causes

Corneal Astigmatism: This is the most common type, caused by an irregularly shaped cornea. Instead of being perfectly round, the cornea has different curvatures in different meridians, similar to the shape of a football rather than a basketball. This irregular shape causes light rays to focus at multiple points, either in front of or behind the retina, resulting in blurred vision.

Lenticular Astigmatism: Less common than corneal astigmatism, this type results from irregularities in the shape of the lens inside the eye. The lens may have variations in curvature or may be tilted, causing similar focusing problems. This type of astigmatism can develop or worsen with age as the lens changes.

Contributing Factors

  • Genetics: Astigmatism often runs in families and is frequently present from birth
  • Eye injuries: Trauma to the eye can alter the shape of the cornea
  • Eye surgery: Certain procedures, particularly cataract surgery, can induce astigmatism
  • Keratoconus: A progressive eye condition where the cornea thins and bulges outward
  • Eye diseases: Conditions affecting the cornea or lens can lead to irregular astigmatism
  • Eyelid pressure: Constant pressure from the eyelids on the cornea may contribute to astigmatism development

Risk Factors

Several factors can increase the likelihood of developing astigmatism or experiencing more severe symptoms:

  • Family history: Having parents or siblings with astigmatism significantly increases your risk
  • Other refractive errors: People with myopia or hyperopia often have some degree of astigmatism
  • Eye conditions: Certain conditions like keratoconus or corneal scarring increase risk
  • Previous eye surgery: Some surgical procedures can induce astigmatism as a side effect
  • Eye injuries: Trauma that affects the cornea's shape can lead to astigmatism
  • Age: While often present from birth, astigmatism can develop or change at any age
  • Ethnicity: Some studies suggest certain ethnic groups may have higher rates of astigmatism

Understanding these risk factors can help individuals and healthcare providers monitor for the development of astigmatism and implement appropriate screening measures, particularly in children who may not recognize or report vision problems.

Diagnosis

Diagnosing astigmatism involves a comprehensive eye examination performed by an eye care professional. Early detection is crucial for preventing vision-related learning difficulties in children and maintaining quality of life in adults.

Diagnostic Tests

Visual Acuity Test: This standard eye chart test measures how clearly you can see at various distances. People with astigmatism often have reduced visual acuity that cannot be fully corrected without addressing the astigmatism.

Keratometry: This test measures the curvature of the cornea using a device called a keratometer. It helps determine the degree and axis of corneal astigmatism by measuring the reflection of light from the cornea's surface.

Refraction: Using a device called a phoropter, the eye care professional determines the exact prescription needed to correct your vision. This test involves looking through various lenses to find the combination that provides the clearest vision.

Corneal Topography: This advanced imaging technique creates a detailed map of the cornea's surface, showing variations in curvature. It's particularly useful for detecting irregular astigmatism and planning refractive surgery.

Additional Assessments

  • Autorefraction: An automated test that provides an initial estimate of your refractive error
  • Retinoscopy: A technique where the examiner shines light into the eye to observe reflections from the retina
  • Wavefront analysis: Advanced technology that measures how light travels through the eye, detecting subtle aberrations

Regular eye examinations are recommended every one to two years for adults and annually for children, or more frequently if you have existing eye conditions or risk factors for vision problems.

Treatment Options

Astigmatism can be effectively corrected using various methods, ranging from non-invasive optical corrections to surgical procedures. The choice of treatment depends on the severity of astigmatism, lifestyle needs, age, and personal preferences.

Non-Surgical Treatments

Eyeglasses: The most common and simplest way to correct astigmatism. Prescription lenses compensate for the irregular curvature of the cornea or lens. Modern lens technologies include:

  • High-index lenses for stronger prescriptions
  • Anti-reflective coatings to reduce glare
  • Progressive lenses for those who also have presbyopia
  • Photochromic lenses that darken in sunlight

Contact Lenses: Various types of contact lenses can correct astigmatism:

  • Toric soft lenses: Specially designed with different powers in different meridians
  • Rigid gas permeable (RGP) lenses: Provide sharper vision by creating a smooth refracting surface
  • Hybrid lenses: Combine a rigid center with a soft peripheral skirt
  • Scleral lenses: Large-diameter lenses useful for irregular astigmatism

Surgical Treatments

LASIK (Laser-Assisted In Situ Keratomileusis): The most popular refractive surgery for astigmatism. A laser reshapes the cornea to correct its irregular curvature. LASIK can correct up to 6 diopters of astigmatism in suitable candidates.

PRK (Photorefractive Keratectomy): Similar to LASIK but without creating a corneal flap. Better suited for people with thin corneas or certain occupations with risk of eye trauma.

LASEK/Epi-LASIK: Variations of PRK with different techniques for preserving the epithelial layer.

Astigmatic Keratotomy (AK): Precise incisions in the cornea to change its shape. Often performed during cataract surgery.

Toric Intraocular Lenses (IOLs): Used during cataract surgery to simultaneously correct cataracts and astigmatism.

Emerging Treatments

  • SMILE (Small Incision Lenticule Extraction): A newer, minimally invasive laser procedure
  • Corneal cross-linking: For progressive astigmatism associated with keratoconus
  • Orthokeratology: Specially designed contact lenses worn overnight to temporarily reshape the cornea

Prevention

While astigmatism often has a genetic component and cannot always be prevented, certain measures can help reduce the risk of developing acquired astigmatism or prevent existing astigmatism from worsening:

  • Protect your eyes from injury: Wear appropriate safety eyewear during sports, work, or activities with risk of eye trauma
  • Maintain good eye health: Regular eye examinations can detect and treat conditions that might lead to astigmatism
  • Manage chronic eye conditions: Proper treatment of conditions like keratoconus can prevent progression
  • Follow post-surgical care: After eye surgery, careful adherence to recovery instructions minimizes complications
  • Practice good eye hygiene: Proper contact lens care and avoiding eye rubbing can prevent corneal changes
  • Control systemic conditions: Managing diabetes and other health conditions that can affect eye health
  • Protect from UV radiation: Wearing sunglasses may help prevent some corneal changes

For children, early detection through regular eye examinations is crucial. Vision screening should begin in infancy and continue throughout childhood to identify and correct astigmatism before it affects learning and development.

When to See a Doctor

While astigmatism itself is not a medical emergency, certain symptoms warrant prompt evaluation by an eye care professional:

Schedule an Appointment If You Experience:

  • Persistent blurred or distorted vision affecting daily activities
  • Frequent headaches associated with visual tasks
  • Eye strain or fatigue that doesn't improve with rest
  • Difficulty driving, especially at night
  • Changes in your vision prescription needs
  • Children showing signs of vision problems (squinting, sitting close to TV, poor school performance)

Seek Immediate Care For:

  • Sudden vision loss or dramatic vision changes
  • Eye pain accompanied by nausea or vomiting
  • Halos or rainbows around lights with eye pain (possible acute glaucoma)
  • Eye injury or trauma
  • Signs of eye infection (redness, discharge, severe pain)

Regular eye examinations are important even without symptoms, as astigmatism and other eye conditions can develop gradually without noticeable symptoms initially.

Frequently Asked Questions

Can astigmatism get worse over time?

Yes, astigmatism can change over time. It may worsen gradually, especially during growth periods in children and adolescents. In adults, significant changes are less common but can occur due to eye injuries, surgeries, or conditions like keratoconus. Regular eye examinations help monitor any changes.

Is astigmatism hereditary?

Yes, astigmatism often runs in families. If one or both parents have astigmatism, their children are more likely to develop it. However, astigmatism can also occur in people with no family history of the condition.

Can astigmatism be cured permanently?

While astigmatism cannot be "cured" in the traditional sense, it can be effectively corrected. Laser eye surgeries like LASIK can provide long-lasting correction, though they don't prevent age-related vision changes. Non-surgical options like glasses and contacts provide excellent vision correction but need to be worn consistently.

Can children outgrow astigmatism?

Mild astigmatism in young children sometimes improves as the eye grows and develops. However, significant astigmatism typically doesn't resolve on its own and requires correction to prevent vision problems and ensure normal visual development.

Does astigmatism affect both eyes equally?

Not necessarily. Astigmatism can affect one eye (unilateral) or both eyes (bilateral), and when both eyes are affected, the degree of astigmatism can differ between them. This is why each eye is measured and corrected separately during eye examinations.

Medical Disclaimer: This information is for educational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or qualified health provider with any questions you may have regarding a medical condition.