Astigmatism: causes and symptoms



Astigmatism happens when cornea– the transparent anterior portion of the eye surface – is curved in an irregular way.

Usually cornea follows a regular curve and refracts light coming inside the eye equally in every part.

In case of astigmatism, the anterior corneal surface appear to be more curved in one direction. In this case we speak of main sections or also of meridians. In this way cornea, p.e. in the main horizontal section, can have a curvature radius that is longer that in the main vertical section.

In case of astigmatism, cornea shape resembles more a rugby ball that a football ball. If light comes through such cornea, the part or the light that is refracted by the more curved corneal surface is focused before the other portion that goes through the less curved portion.

This looks complicated but in the end, it only means that there are two focal points for different parts of the cornea – one in an anterior part, the other in a posterior part. A single point in the space of an object is not seen as a single point on the retina. If we add myopia or hypermetropia to the mix, we’ll probably end up with a blurred ellipse on the retina.

Astigmatism symptoms

The effect of astigmatism is similar to what you seen when looking to a curved mirror. The eye cannot gather all ray of light in a single point. Astigmatism symptoms may vary depending on how serious it is.  Light degree astigmatism has no symptoms at all, or some like:

  • paint in the ocular bulbs and/or ciliary arches,
  • migraines, a sense of heaviness in the eyes
  • eye burning and/or excessive lacrimation
  • lines appear distorted

Medium to high degree astigmatism usually feature blurred vision when focusing on both near or far objects. In the menu you’ll find a test to verify if you have astigmatism.

Astigmatism causes

Astigmatism is usually caused by an irregular cornea or lens curvature.

During the initial and intermediate phases of cataract, or after metabolic alterations (e.g. diabetes) astigmatism can appear after an alteration of the lens refraction index. Astigmatism can also be caused by cataract surgery performed with old fashioned techniques.

When astigmatism increases during adolescence, that could be a sign of a disease called keratoconus that often features myopia and astigmatism that quickly develop over time.

Stop using glasses and contact lenses

Today, it is possible to correct astigmatism using glasses, contact lenses, or thanks to the astigmatism laser surgery. It is possible to remove glasses and contact lenses, curing astigmatism for good, using:

  • Excimer laser
  • Femtosecond laser
  • Intraocular Toric Lenses that substitute the lens
  • Intraocular contact lenses or toric phakic lenses.

The latest news is the intraocular High Tech lens, customizable with laser. This surgery to cure astigmatism has been performed in Milan for the first time by Dr. Badalà in 2010.

Exercises to (not) cure Astigmatism

It may have happened to you to hear of several techniques to cure astigmatism for good in natural ways, without surgeries or glasses.

One of these techniques is called orthokeratology. It consists in wearing special contact lenses over night, removing them in the morning: vision should be improved.
What happens is that these contact lenses warp the cornea, flattening it during the night, so that the next day the patient sees better. The work like a corset that, if worn over night, makes you look thinner the next day.

There’s the risk of damaging the cornea with these iterated deformations. Another possibility that is often described consists in visual exercises: patient should focus on far objects in order to train the eye to see better. Unfortunately there is no evidence that this process achieves results. There is the risk though that the eye of the patient could become fatigued and experience burning sensations or migraines.