What is Astigmatism?
Astigmatism is a fairly common condition that causes a person’s vision to be blurry or distorted. This condition is called a “refractive error,” which is a vision problem that results from irregularities in the shape of your eye that affect how your eye “bends” or “refracts” light in order to see clearly.
When a person has astigmatism, the front surface of the eye, known as the cornea or the lens, has irregularities in its curvature. This prevents light from properly focusing on one point of the retina, which causes blurry vision regardless of how near or far you are from something. Astigmatism is often accompanied by other refractive errors, namely:
- Myopia or nearsightedness
- Hyperopia or farsightedness
A typical and healthy eye has a curvature similar to a perfectly round ball, while an eye with astigmatism is shaped like an egg. Adults who develop astigmatism can usually detect a change in the way they see things around them.
Children who have acquired astigmatism at birth may not be able to tell the difference, which is why it’s important to have them undergo regular eye exams to determine any problems.What are the Symptoms of Astigmatism?
The most common symptom of astigmatism is having blurry or distorted vision. If you notice your eyesight becoming blurry, it may also be a sign of other vision problems like nearsightedness or farsightedness. Other symptoms of astigmatism include:
- Squinting to improve vision
- General discomfort in the eyes
How is Astigmatism Diagnosed?
Only a licensed ophthalmologist or optometrist can perform a comprehensive eye exam needed to diagnose astigmatism or any vision problems. When an ophthalmologist or optometrist tests for astigmatism, they look into how your eye focuses on light. An eye examination may include the following tests:
Visual Acuity Test
This test measures a person’s visual acuity by determining the smallest letters they can read on a visual acuity chart, which can be letters or photos. Usually, the doctor will ask you to cover one eye while you attempt to read the smallest letters on the chart.
This eye exam will measure how well your eyes are able to focus. During this test, the doctor will ask you to sit on a chair with a “phoropter” or “refractor” in front of you. You will then look through the phoropter and try to name all the letters on an eye chart located six meters away from you.
The doctor will change the lens for both eyes and will ask you which looks clearer or blurrier, in order to determine the strength needed for your prescription glasses.