Wednesday, April 4, 2012

Astigmatism 101

What is Astigmatism? It's a funny word, isn't it? Lots of people think the word is "stigmatism" and that you have "a stigmatism". That of course means that you could have one or more "stigmatisms", but that's not really how it works!

Astigmatism is an optical term that relates to how an optical system focuses, or doesn't focus, light. In our situation the optical system is the eye! There are three different parts of the eye that make up the focusing elements of our vision system: the TEAR FILM that sits on the very surface of the eye (that's why Dry Eye causes vision problems!), the CORNEA or window to the eye, and the LENS that sits in back of the pupil. Astigmatism is present when the combination of these pieces parts creates two or more focused images from a beam of light.

Most of the time astigmatism is caused by the shape of the CORNEA. In a normal eye, one without astigmatism, the cornea is like the front of a sphere; it's round like a basketball or a soccer ball. A cornea that has astigmatism is longer in one direction than the other. It's STEEPER in one direction and FLATTER in the other. In other words the astigmatic cornea is shaped like a football instead of a basketball.

Whether you are nearsighted or farsighted, if you have astigmatism you will have at least two images focused in the eye. There are lots of ways to correct this, and we'll talk about all of them as time goes on. Be sure to check here, and watch for the videos on the Dr. Whiteboard over on Youtube for more info on ASTIGMATISM.

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