Astigmatism

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Astigmatism

  • Around 30% of the general population is astigmatic.
  • More than 80% of people with myopia or hyperopia are also astigmatic.
  • Operable up to 6 dioptres using laser or intraocular lenses.

What is Astigmatism?

Astigmatism is a refractive defect that causes images to focus on the retina in a distorted way. It affects both near and far vision and can occur on its own or in combination with myopia (nearsightedness) or hyperopia (farsightedness). Typically, astigmatism is stable throughout life.

What Causes Astigmatism?

Astigmatism is primarily caused by:

  • Corneal irregularities: The cornea loses its spherical shape and becomes elliptical, which impedes the ability to focus clearly on near and far objects.
  • It may be hereditary or develop as a result of:
    • Trauma or disease.
    • Surgical procedures.

How Can Astigmatism Be Prevented?

Astigmatism cannot be prevented, but it can be diagnosed through an ophthalmological examination. Common tests include:

  • Refraction test.
  • Corneal topography (if needed).
  • Additional tests may be required in special or complex cases.

Symptoms

The symptoms of astigmatism can vary depending on age, type, and degree of the condition. Common symptoms include:

  • Distorted images (the most common symptom).
  • Poor visual acuity in far vision.
  • Difficulty switching between near and far vision.
  • Problems seeing fine details in both near and distant objects.
  • Headaches, eye pain, or dizziness, often due to the eye's muscular effort to compensate for the defect, especially in cases associated with hyperopia.
  • In cases of low astigmatism, vision may not be significantly affected.

Associated Treatments

Astigmatism can be corrected through:

  • Glasses or toric contact lenses.
Surgical Treatment

If the patient prefers not to wear glasses or contact lenses, several surgical options are available:

  • Excimer laser: Applied to the corneal thickness to correct moderate astigmatism. Often combined with femtosecond laser.
  • Incisional technique (Arcuate keratotomy): Used for high astigmatism, involving incisions on the corneal surface.
  • Toric intraocular lenses:
    • Phakic lenses (implanted between the cornea and crystalline lens).
    • Pseudophakic lenses (replace the crystalline lens). Used for high astigmatism correction.

The ophthalmologist will determine the most appropriate technique for each case.

Success Factors in Surgery

Approximately 80% of surgery success depends on:

  • Proper diagnosis.
  • Selecting the appropriate surgical technique.
Surgical Options Include:
  • Intrastromal corneal rings.
  • Refractive surgery with intraocular lenses.
  • Laser refractive surgery.
  • Femtosecond laser.