Astigmatism, it’s a word that you will hear often when people are talking about eye-wear corrections, but what exactly is it? Most of us are aware that it has something to do with the eye being misshapen, but in what way exactly? The best way to describe it is to compare the eye to something more familiar. A “perfect” cornea (the soft portion of the eye where light is focused onto the lense) is usually more spherical in shape, like a baseball, an astigmatic cornea (or eye) is more conical in shape, like a football. This causes light to be refracted unevenly onto the lens at the back of the eye, thus lowering the quality of your vision.
Now that we have defined the basics of astigmatism, let’s take a closer look at the three primary types of astigmatism. First of all there is myopic (or nearsighted) Astigmatism, this is where the astigmatism causes nearsightedness. There is also an astigmatism that causes farsightedness, and mixed astigmatism. Which presents when the principal meridians (the steepest, and most flat parts of the eye) are both farsighted and nearsighted. There is one other kind of astigmatism, lenticular. This is not as common as the other types of astigmatism, because it is caused by a misshapen lens.
After those classifications there are even more subcategories of astigmatism that are based off of the angles of the principal meridians. This may seem like mumbo jumbo at this point, but to doctors those angles have a substantial amount of importance, as irregular astigmatism is often indicative of an eye injury, or some other underlying eye condition.
So why is all this important and how do we fix it? Well astigmatism is a particularly frustrating thing to have as it often can make objects at a distance blurry, as well as objects in close proximity to you. This of course can cause a great deal of frustration, and what’s more, most children are born with some form of astigmatism or another, and because most things are blurry for them, they can go years without indicating to someone that they are having visual difficulties. So it is important to have your child’s vision screened regularly.
As far as correcting this is concerned, this is accomplished by adding (or removing if you are farsighted) power to the lens of your glasses. This power is often referred to as cylinder. The reason that this correction is marked differently is because this power is located at a specific “axis,” which is what allows it to refract light in the specific way that is most advantageous to your visual correction.
The axis somewhat refers to the angle at which light is redirected through the cornea. This number between 0 and 180 plays an important role in the way that you see through your glasses, in that it directs light to a very specific area of the retina, which allows for your vision to be optimized.
As you can see there is a lot that goes into diagnosing and correcting astigmatism, and there are numerous factors that change how it is corrected. But our hope is that with this new information you can better understand some of the numbers on your vision prescription!
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