Q: What is Astigmatism?

A: Astigmatism is a problem with the way an eye focuses light. Most people are familiar with the terms near-sightedness (myopia) and far-sightedness (hyperopia). People who have myopia can see things clearly up close, but their vision is blurry when they look at objects that are farther away. Hyperopic, or far-sighted people, actually can have good vision at distance, but they have to strain their eyes somewhat to do so. The closer an object is, therefore, the more they have to strain. Astigmatism, on the other hand, makes vision blurry at all distances.

Imagine the lens of a magnifying glass. It is perfectly smooth and round on its face, like a slice through a basketball. Then imagine that this magnifying lens is squishy. If you squeeze the sides and squish it towards the middle, the shape changes. It is more like a slice through the side of a football – steeper in one direction than the other. This is the classic description of astigmatism, a slice through a football. You can imagine how having a camera lens like this would take lousy pictures!

Fortunately, if you put a different football-shaped lens in front of the first you can counteract the weird shape of the first lens. Of course the lens has to be lined up properly and has to have the right amount of power. This is what is done with a pair of prescription eyeglasses.

Hall T. McGee, M.D., Everett & Hurite Ophthalmic Association, can be reached at (412) 288-0885 or mcgeeh@gmail.com

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