For many people, astigmatism sounds like a horrible eye condition. It sounds like, at any minute, the eye could explode, melt and fall out on the ground in front of you. The truth is that astigmatism is really a description of a particular vision error that creates blurred vision. Other such types of vision errors are myopia (nearsightedness) and hyperopia (farsightedness). Astigmatism is different in that it really describes the effect of an oval or oblate shaped eye.
This is where the “football shaped eye” analogy has gained popularity. The “normal” human eye is mostly round in shape like a basketball. No matter what path you take around the ball, the curvature is the same. This is true of eyes that have nearsightedness and farsightedness. The difference being the eye with nearsightedness is a vision system that is too strong and images focus in front of the retina. And farsightedness focuses an image on a hypothetical position behind the retina. Both of these create blurry images for the individual.
However, the eye with astigmatism, like a football, will have a curvature along one meridian that is different from the curvature in another meridian. With a football, the curvature from the nose to the tail of the ball is much different than the curvature around the belly of the ball where the stitches lie. While the eye with astigmatism is not quite this dramatic, it’s a very effective analogy.
The result of this “football shape” is the creation of two different focal points. Nearsightedness and farsightedness might create blurry images, but they still create a single focus point–either in front or in back of the retina, respectively. But, the 2 separate focal points created by astigmatism creates an entirely different experience of blurred vision.
Blurred vision from astigmatism can affect distance and up-close vision. It can affect one more than the other. It can also create double or shadowing-type vision. It may induce squinting in a subconscious attempt to reshape the eye into a more rounded state. Astigmatism tends to change over time. The optometrist measures astigmatism in two different ways: amount and orientation (or axis). The amount may change over time. The orientation or axis of astigmatism seems to be more prone to changing over time. This changing axis often necessitates yearly updates to glasses prescriptions depending on the amount of astigmatism and the shifts in axis experienced.
It used to be the case that patients with astigmatism could not wear contact lenses. That’s no longer the case for most patients with astigmatism. Modern contact lens technology has drastically increased our ability to successfully fit these patients with comfortable contact lenses that provide sharp and clear vision.
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