What is astigmatism?
Astigmatism is a refractive defect that causes images to focus on the retina in a distorted way, affecting near and far vision.
Astigmatism can occur by itself or in association with myopia or hyperopia, and is usually stable throughout life
What causes it?
Astigmatism is usually caused by a problem in the curvature of the cornea that impedes clear focusing on near and far objects. The cornea loses its spherical shape, becoming elliptical.
The cause of this irregularity is often genetically determined, but may also occur as a result of trauma, disease or after surgical procedures (such as corneal transplantation).
How can it be prevented?
Astigmatism cannot be prevented but can be diagnosed through an ophthalmological examination that includes a refraction test and/or corneal topography. Certain special or complex cases may require other types of test.
Symptoms can vary depending on age and type and degree of astigmatism. If the astigmatism is low, it may not affect vision.
The most common symptoms are:
- Perception of distorted images (most common symptom).
- Poor visual acuity in far vision.
- Problems in switching between near and far vision.
- Difficulties in seeing fine detail, either near or distant.
- Headaches, eye pain or dizziness, as a result of the eye’s muscular effort in trying to compensate for the defect with the accommodation of the crystalline lens (the eye’s natural lens whose elasticity enables the eye to focus). This is especially true in cases of astigmatism associated with hyperopia.