What causes astigmatism?

The eye has two curved surfaces called the cornea and the lens. The cornea is the name of the transparent layer covering the front surface of the eye. The lens, on the other hand, is the transparent structure inside the eye that is invisible from the outside, becomes thinner, and allows focusing on objects. In a perfect eye, the lens and cornea have a rounded curvature of equal diameter, like a smooth ball surface. A cornea and lens with the right curvature refract incoming light rays, creating a direct and sharply focused image on the retina at the back of the eye. If the cornea or lens has an uneven, egg-shaped curvature, the light rays are not refracted properly, resulting in a blurry image. This curvature of the cornea or lens that is greater than the other side is called astigmatism.

If the cornea has unsuitable folds, it is corneal astigmatism, and if the lens has unsuitable folds, it is lenticular astigmatism. Both types of astigmatism can cause blurred vision. Blurred vision may be more in one direction, such as horizontal, vertical, or diagonal.

Astigmatism may be present from birth or develop after injury, illness, or eye surgery. Factors such as reading a book in poor light, sitting too close to the TV, or having strabismus do not cause astigmatism to progress. Astigmatism is more common in premature babies than in others. ‌

What are the symptoms of astigmatism?

  • Blurred or distorted vision at all distances
  • Headache
  • excessive drooping of the eyes
  • Eye strain in activities that require the eye to focus for long periods of time (such as prolonged reading on a printout or screen)
  • Difficulty driving at night
  • double vision in severe cases

If you have these symptoms, you should see a doctor.

How is astigmatism treated?

Mild conditions may not need treatment. If astigmatism is severe, glasses, contact lenses, and sometimes laser surgery are recommended for treatment.