Astigmatism is an eye condition where light doesn’t hit the back of your eye evenly. It happens when either your cornea or lens aren’t perfectly round. Instead, it’s shaped like a football. That can make things look blurry or distorted.
An eye doctor can easily diagnose and treat astigmatism. But there are also ways to check for astigmatism at home, although you should still be seen in person by an eye doctor. Here's what you need to know.
Eye Charts and Dials
These are pictures that show straight lines at different angles. When you have astigmatism, some of the bold lines will look blurrier than others. It may look like some are drawn with a black marker and others are faded. That’s because the abnormal curve of your eye makes parts of a picture more or less clear.
Some examples you can find online include:
Astigmatic dial. This is a chart that looks like rays of sunshine.
Half dial. On this picture, vertical lines shoot out like a folding fan.
Blocks of vertical and horizontal lines. This is a set of vertical lines directly on top of horizontal lines.
All the charts work the same way. You’ll stand or sit 2-3 feet away from your computer or smartphone screen. If you have glasses that don’t fix your astigmatism, you can keep them on. Cover your left eye first. Look at the picture with your right eye. Look for any differences in the lines. Now do the same thing with your other eye.
If any of the lines look darker or thicker than the others, then you might have astigmatism. If the vertical lines look sharper, then you have “with-the-rule” astigmatism. If the horizontal lines pop out, then you have “against-the-rule” astigmatism.
Visual Acuity Tests
Astigmatism often makes your eyesight fuzzy both at a distance and up close. You can look at letters on a chart to see how sharp your vision is.
Online tests often use the “Tumbling E” method. You don’t need to be able to read to use this one. That makes it a good option for kids. The arms of the E might point up, down, right, or left. It’ll get smaller with each question.
To take the test:
- Sit 3 feet away from your screen.
- Click on the arrow that shows which way the letter E is pointing.
To use an eye chart at home, you’ll need to:
- Print the chart.
- Place the chart on a wall with no windows on it.
- Place a chair 10 feet away from the wall. Sit in the chair.
- Make sure the chart is at eye level.
- Cover one eye.
- Read the smallest letters you can see clearly.
- Repeat with the other eye.
For a Tumbling E chart, you can use your finger to show which direction the E is pointing.
By age 5, kids should be able to read the line that says 20/30. Older children and adults with normal vision should be able to read the 20/20 line. If not, that means your eyesight isn’t as clear as it could be. Keep in mind that conditions other than astigmatism can cause blurry vision. You can also have astigmatism even with sharp eyesight.
When to See a Doctor
You may not need to do anything for mild astigmatism. An eye exam by a professional will tell you. An online assessment at home is not a replacement for a professional exam, but can give you an idea of how quickly you may want to be seen by an Eye Doctor. Glasses, contacts, or surgery can help you see better.
Kids with astigmatism may not tell you about their vision problems. It’s important to watch for certain signs. If they can’t see well, they might start to have trouble in school. Ask your child’s doctor how often they should get their eyes checked.
Check with an eye doctor if you or your child have symptoms such as:
- Blurry vision at any distance
- Double vision in either eye
- Frequent headaches
- Lots of squinting
- Tired or strained eyes
- Trouble seeing at night