Testing for Astigmatism

Astigmatism is a common refractive error that happens when parts of the eye are irregularly shaped, preventing light from focusing properly on the retina. As a result, people with this condition complain of blurred and distorted vision. This refractive error occurs in about one in three people and may occur in combination with near- or farsightedness.1

Getting a comprehensive eye exam is the best way to diagnose astigmatism. An optometrist or ophthalmologist will perform a few tests to see how the eyes focus light and the power of any corrective lenses needed to improve vision.2 Astigmatism tests can also be found online, but an eye doctor's exam is needed for a precise diagnosis.

 What Is Astigmatism?

Astigmatism occurs when the cornea (a transparent layer in front of the pupil that focuses light into the eye) or lens (sits behind the pupil and helps light focus onto the retina) has an irregular shape. While a normal cornea has a spherical shape, the area in people with astigmatism will be oval-shaped.

In an eye without astigmatism, light bends (refraction) when entering the eye and goes through two different parts: first the cornea and then the lens. When either of them has an abnormal shape, the light will scatter instead of focus properly on the retina, which is responsible for sending lights as electrical impulses to the brain. As a result, the images at any distance will become blurry.

Symptoms of astigmatism include:

• Blurred vision
• Double vision
• Eyestrain or eye discomfort
• Headaches
• Fatigue
• Low night vision
• Squinting