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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.
153 million people around the world have a refractive error. Other common refractive eye errors include nearsightedness (myopia) and farsightedness (hyperopia).
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.
Astigmatism may distort the appearance of lights. This can make driving at night difficult.
Visual distortions caused by astigmatism include:
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.
Astigmatism can impair vision at night and make driving difficult.
People with astigmatism may notice:
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.
The most common symptoms of astigmatism are:
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.
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.
Many treatment options are available to help you see better.
The most common treatments include:
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.
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