Much like nearsightedness (myopia) and farsightedness (hyperopia), astigmatism is not a disease of the eye. Rather, it’s a refractive error in your lens that you are born with and that is usually treated with glasses, contact lenses, or surgery. Symptoms include blurred or distorted vision, eyestrain, and or headaches (especially after attempting to focus for some time). People with astigmatisms will also commonly squint to try to focus on text or other objects that they have to maintain focus on for more than a few seconds.
WHAT CAUSES ASTIGMATISM?
Astigmatism occurs when your cornea is not spherical, but instead has an irregular curvature. With a normal eye (with no astigmatism), the curvature over the cornea is uniform, and the eye is able to evenly and equally focus all light that enters. However, with astigmatism, the cornea is curved more in one direction than another, and the eye effectively has one focal point in the vertical plane and another focal point in the horizontal plane, per their respective curvatures.
We can define different types of astigmatisms based on how they affect your vision. For example, in the case of a myopic astigmatism, one or both curvatures are nearsighted, whereas in a hyperopic astigmatism, one or both curvatures are farsighted. A mixed astigmatism occurs when one curvature is nearsighted and the other is farsighted.
SYMPTOMS OF ASTIGMATISM
You may have astigmatism in one or both eyes if:
- You have more trouble focusing with one eye than with the other at close or near distances.
- You get headaches or feel significant eyestrain or fatigue when you try to read (especially on a computer screen) for more than a few minutes at a time.
- Your vision is wavy, blurred, or distorted in one or both eyes.
These symptoms may indicate astigmatism, but they may also indicate other vision problems. If you experience any or all of these, make an appointment with your eye doctor immediately for diagnosis and treatment.
HOW IS ASTIGMATISM DIAGNOSED?
Your ophthalmologist can and will test for astigmatism during a regular eye exam. Traditionally, this is done by retinoscopy by shining a light through different lenses onto your eye. This method is still used today, though it is sometimes replaced or supplemented with tests performed with automated refraction instruments.
OPTIONS FOR CORRECTING ASTIGMATISM
Astigmatism can be corrected with eyeglasses or with hard or soft contact lenses. However, if you are tired of wearing glasses or contacts, most cases of astigmatism can also be treated with either LASIK or PRK surgery. These surgeries use lasers to shave away part of the cornea and reshape it into a perfect sphere, eliminating the need for glasses or contact lenses.