Astigmatism

What is Astigmatism?

Astigmatism is a common refractive error that occurs when the cornea or lens has an irregular shape, causing blurred or distorted vision. Unlike myopia (near-sightedness) or hyperopia (far-sightedness), which affect vision at specific distances, this refractive error can impact vision at all distances. This condition is often present from birth and can change over time, necessitating regular eye tests.

What is the Cause?

It occurs due to an irregular curvature of the cornea or lens. Instead of being perfectly, round, the cornea is shaped more like a football, which prevents light from focusing evenly on the retina. This results in blurred or distorted vision. The exact cause of is not always known, but factors that contribute to its development include:

• Genetics: Often inherited, meaning it can run in families.
• Eye injuries or surgery: Trauma or surgical procedures can alter corneal shape.
• Keratoconus: A progressive condition that thins and reshapes the cornea.

Common Symptoms

Symptoms can vary in severity but often include:

• Blurred or distorted vision
• Eye strain or discomfort
• Headaches, especially after reading or screen use
• Difficulty seeing at night
• Squinting to improve focus

How is it Diagnosed?

Astigmatism is detected through standard eye tests, including:

• Visual acuity test: Measures clarity of vision at different distances.
• Refraction test: Determines the lens prescription needed for clear vision.
• Keratometry and topography: Measures corneal curvature to assess the severity.

Treatment Options

The most effective treatments include:

1.Prescription Glasses

Glasses with cylindrical lenses correct uneven refraction, improving vision clarity. This is a simple, non-invasive solution suitable for most individuals.

2. Contact Lenses

• Toric lenses: Specialty designed soft lenses that correct astigmatism.
• Rigid gas-permeable (RGP) lenses: Provides sharper vision for moderate to high astigmatism.
• Hybrid lenses: Combine a rigid centre with a soft outer ring for improved comfort and vision.

3. Laser Eye Surgery

• LASIK (Laser-Assisted in Situ Keratomileusis): Reshapes the cornea to correct it.
• PRK (Photorefractive Keratectomy): Removes a thin corneal layer to improve shape.
• SMILE (Small Incision Lenticule Extraction): A minimally invasive laser surgery option.

4. Orthokeratology (Ortho-K)

Ortho-K involves wearing specially designed rigid contact lenses overnight to temporarily reshape the cornea and provide clear vision during the day.

5. Implantable Lenses (ICL)

For those who are not candidates for laser surgery, implantable contact lenses can provide a long-term solution.

Importance of Regular Eye Tests

Astigmatism can change over time, making regular eye tests essential for maintaining optimal vision. An optometrist can adjust prescriptions as needed and recommend suitable treatments based on changes in your vision.