Astigmatism is a common and treatable eye problem that causes blurry or distorted vision. In the United States, one in every three people has astigmatism.
Astigmatism is a refractive error, which means the shape of your eye doesn't bend or refract light rays correctly.
The two types of astigmatism are corneal and lenticular. Astigmatism occurs when your cornea or lens curvature is abnormal. This causes blurred vision at all distances.
With corneal astigmatism, the cornea has more of an oval shape instead of a round shape. With lenticular astigmatism, the lens is misshapen. In a normal eye, each of these elements is almost perfectly round.
An irregular cornea or lens prevents the eye from focusing light correctly on the retina. The area in the eye converts light into signals sent to the brain for visual recognition.
Astigmatism occurs naturally or is caused by an eye injury, eye disease, or eye surgery.
How Do Lights Look With Astigmatism?
Astigmatism may distort the appearance of lights. This can make driving at night difficult.
Visual distortions caused by astigmatism include:
Blurriness
Glare
Streaking
Starburst
Halo effect
Here are some examples of how lights may look with astigmatism:
Glares or a halo appearance around lights do not necessarily indicate astigmatism. This can also be caused by other vision conditions like nearsightedness (myopia) or cataracts.
How Does Astigmatism Affect Night Driving & Vision?
Astigmatism can impair vision at night and make driving difficult.
People with astigmatism may notice:
Blurring or fuzziness around lights and other objects
Halos around lights
Lights appearing ‘streaky’
Increased glare from lights
Increased squinting to see more clearly
It can be dangerous to drive at night with untreated astigmatism. Streetlights and headlights can be distorted, increasing the chance of an accident.
If you have trouble with your night vision or notice any of these symptoms, immediately schedule an exam with your eye doctor.
Symptoms of Astigmatism
The most common symptoms of astigmatism are:
Blurry vision
Needing to squint to see clearly
Headaches
Eyestrain
Difficulty seeing at night
If you have mild astigmatism, you might not notice any symptoms. That’s why it’s essential to get regular eye exams.
An optometrist or ophthalmologist can diagnose astigmatism even if you don't notice it. All children should visit a pediatric optometrist at least once a year.
How is Astigmatism Diagnosed?
An optometrist can diagnose astigmatism during a regular eye exam.
A typical eye exam includes:
A visual acuity test to check the ability to discern shapes and details.
A refraction to determine your refractive error (including astigmatism). The eye doctor bases your eyeglass prescription on the results of this test.
A visual field test to check the peripheral (side) vision.
An eye muscle function test to check for issues with the muscles around the eyeballs.
A pupil response test to check how your pupils respond to light and viewing objects at near.
A tonometry test to measure eye pressure.
Dilation to check for problems with the inner parts of the eyes.
Treatment for Astigmatism
Many treatment options are available to help you see better.
If you have glasses or contacts for astigmatism, wear them when driving at night. If you still have trouble with night vision, see your eye doctor. You may need to have your prescription adjusted or find an underlying cause.
Melody Huang is an optometrist and freelance health writer. Through her writing, Dr. Huang enjoys educating patients on how to lead healthier and happier lives. She also has an interest in Eastern medicine practices and learning about integrative medicine. When she’s not working, Dr. Huang loves reviewing new skin care products, trying interesting food recipes, or hanging with her adopted cats.
Kyra is a freelance writer based in California who specializes in copywriting and content writing. She enjoys writing about health & wellness, science, and medical topics. She graduated from Rutgers University with a degree in English literature.
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