Astigmatism- Causes, Symptoms, Diagnosis, Treatment & Prevention

What is Astigmatism?

Astigmatism is a focusing problem which results in reduced clarity of vision. The word is derived from Greek “stigma” meaning “point”. “Astigma” means “no point”, because in astigmatism the light rays do not come to a point focus on the retina. Astigmatism is caused by a defect in the curvature of the eye’s cornea or lens. When the shape of the cornea or lens is not completely spherical (like a soccer ball), it has astigmatism (i.e. like a football). This imperfection of the eye is, however, generally treatable.

In Astigmatism, when light enters your eye, it gets bent more in one direction than in the other, giving blurred or unclear vision.

Types of Astigmatism

Astigmatism can be divided broadly into two types:

  1. Corneal Astigmatism: It is when the shape of the cornea is not spherical.
  2. Lenticular Astigmatism: It is when the shape of the lens is not spherical.

The pattern of astigmatism can be either:

  1. Regular, or
  2. Irregular. Irregular astigmatism cannot be corrected with glasses, and is associated with a condition known as keratoconus.

Astigmatism’s Symptoms

Astigmatism can have a variety of symptoms:

  1. Blurry or distorted vision, usually at all distances (far and near)
  2. Eyestrain
  3. Headache
  4. Trouble seeing at night time
  5. Squinting

Causes of Astigmatism

The exact causes of astigmatism are not always clear, but several factors may contribute to its development:

  1. Genetics: A significant factor in astigmatism is genetics. If a person has a family history of astigmatism, they may be more likely to develop the condition themselves.
  2. Corneal Shape: The cornea, the clear front surface of the eye, is a crucial element in focusing light onto the retina. Irregularities in the shape of the cornea can lead to astigmatism.
  3. Lens Shape: The lens inside the eye, which helps fine-tune focus, can also contribute to astigmatism if it has an irregular shape.
  4. Eye Injury or Surgery: Trauma to the eye or certain eye surgeries may alter the shape of the cornea or lens, leading to astigmatism.
  5. Keratoconus: This is a condition where the cornea progressively thins and takes on a more cone-like shape, leading to irregular and high degrees of astigmatism.
  6. Premature Birth: Infants born prematurely may be at a higher risk of developing astigmatism.
  7. Degenerative Changes: Aging can sometimes cause changes in the shape and flexibility of the lens, contributing to astigmatism.
  8. Eye Conditions: Certain eye conditions, such as corneal scars or thinning, may induce astigmatism.
  9. Muscle Imbalance: Conditions where the eye muscles are imbalanced may result in astigmatism.

When should I have my eyes examined?

It is recommended to have a comprehensive eye examination at least once every two years for adults with no known vision issues. However, if you have existing eye conditions, wear glasses or contact lenses, or are over 40, annual exams are advisable. Children should have their first eye exam at around six months of age, with follow-ups as recommended by an eye care professional.

If you experience sudden changes in vision, eye discomfort, or other issues, schedule an appointment promptly. Regular eye exams are crucial for maintaining overall eye health and detecting potential problems early.

How can Astigmatism be Diagnosed?

Astigmatism can be diagnosed through a visit to your optometrist or ophthalmologist. They are likely to do a complete eye test to help diagnose the problem.  

There are likely to be multiple eye tests, including your reading tests, to determine the clarity of your vision. The other tests could be:

  1. Refraction Test: A refraction test is done to determine the glasses or contact lens prescription needed to see perfectly. Your doctor will ask you to read a chart while looking through lenses of different strengths. This way, they will be able to find the lens(es) that work best for the shape of your eye. In infants and young children, retinoscopy is performed as an objective measure of refraction.
  2. Keratometry: Keratometry is a way for your eye doctor to measure the curvature of your cornea.
  3. Topography: A topography machine provides detailed information about the shape of the cornea, including whether there is any astigmatism present and whether it is regular or irregular.
astigmatism

How can Astigmatism be Treated?

If you have mild Astigmatism, it is likely to be cured through corrective lenses. This is the most common and easy way.

  1. Glasses: These are shaped to counteract the astigmatism of the cornea or lens that is causing blurred vision, allowing you to have clearer vision. The lenses of the glasses make the light bend into your eye properly. Eyeglasses can also be used to correct the other refractive errors, such as near-sightedness or far-sightedness.
  2. Contact Lenses: Contact lenses are another option to correct Astigmatism. If you have mild Astigmatism, you can use toric contact lenses. These lenses are designed in such a way that they return to the same spot every time. In case you have severe or irregular Astigmatism, you may benefit from rigid gas permeable (RGP) contact lenses.

Another way of treating Astigmatism is surgery. Multiple types of surgeries can be performed for Astigmatism:

  1. LASIK: The shape of the cornea is changed so that it can focus light rays more precisely on the retina. The surgeon makes a thin, hinged flap in your cornea. This exposes the central layers of your cornea, and a precise specialised laser is used to sculpt the cornea into a different shape. The surgeon then returns the flap to its original position.
  2. Photorefractive keratectomy (PRK): In this surgery, the surgeon removes the epithelium of the cornea, without a hinge or flap. This exposes the central layers of your cornea, and a precise specialised laser is used to sculpt the cornea into a different shape. The epithelium then grows back naturally, conforming to your cornea’s new shape.

Along with the benefits, all surgeries have their own sets of risks and complications. Therefore, talk to your ophthalmologist about all the risks and complications, and to assess whether you are suitable for any of these options.

How can Astigmatism be prevented?

It is important to avoid eye-rubbing as much as possible, as it can cause and worsen astigmatism. Treatment of allergy is important to reduce itchiness, which is a trigger for eye rubbing.

Conclusion

If not treated, distorted or blurred vision due to Astigmatism is likely to continue for a lifetime. Treatment is usually straightforward in most patients with glasses, contact lenses, or laser vision surgery.

Dr Parth Shah is a Canberra-based ophthalmologist known for his experience in providing treatment for eye problems, including Astigmatism. He is thorough in his knowledge of modern techniques and implements them in patient care.

FAQs

  1. Can children have astigmatism?

    Yes, astigmatism can occur at any age, including childhood. Regular eye exams for children are important to detect and address astigmatism early, as it can impact learning and development.

  2. Can astigmatism be corrected permanently?

    Refractive surgeries like LASIK or PRK can provide a more permanent correction for astigmatism by reshaping the cornea. However, the eligibility for surgery depends on various factors and should be discussed with an eye care professional.

  3. Can astigmatism cause other eye problems?

    Astigmatism itself doesn’t cause other eye problems, but uncorrected astigmatism may lead to eye strain and discomfort.

  4. Can astigmatism change over time?

    Yes, astigmatism can change, and it may progress or stabilise over time. Regular eye exams are essential to monitor any changes in vision and adjust corrective measures accordingly.

  5. What do the numbers in an astigmatism prescription mean?

    Astigmatism prescription includes two values: cylinder (Cyl) and axis. The cylinder (in diopters) indicates the amount of astigmatism correction needed, and the axis (in degrees) specifies its orientation. For example, +1.50 D x 180° means a +1.50 diopter cylinder with astigmatism along the horizontal meridian. Follow your eye care professional’s prescription precisely for accurate correction.

  6. What foods improve astigmatism?

    While specific foods may not directly improve astigmatism, maintaining a balanced diet is essential for overall eye health. Incorporating nutrient-rich foods such as leafy greens, carrots, citrus fruits, nuts, seeds, fatty fish, bell peppers, and whole grains can provide essential vitamins and minerals.

    These nutrients support eye health and may contribute to preventing age-related damage. Remember to complement a healthy diet with regular eye check-ups and practices that reduce eye strain, ensuring the best care for your eyes.

Author Bio

Dr Parth Shah is an experienced ophthalmologist in Canberra, specialising in cataract surgery. With extensive training and experience, he is renowned for his expertise in the field. Dr Shah is dedicated not only to performing successful surgeries but also to patient education. His compassionate approach, combined with technical proficiency, has earned him the trust and gratitude of countless patients. He is a true advocate for eye health and a trusted name in the Canberra ophthalmology community.