The word “Astigmatism” is often mispronounced, misunderstood – or simply not understood at all. However, of those who wear eyeglasses, a large majority actually suffer from some sort of astigmatism. So why don’t we know what it is? It’s actually pretty simple once you learn a bit more about it. Typically our eyes are shaped like a round ball; however with an astigmatism the eye is elongated – more like a football. Having an astigmatism does not mean that there is a problem with the health of one’s eyes; simply that due to interactions with light, the eye has an issue focusing correctly. Instead of light coming in to a central location and pinpointing it with clear vision, it appears from multiple points of view – both in front of, and behind the retina.
There are a several different kinds of astigmatisms, and they can be broken down a few different ways: myopic astigmatism, hyperopic astigmatism, and mixed astigmatism, and regular and irregular astigmatism. Like nearsightedness in vision, myopic astigmatism affects meridians of the eye in a nearsighted fashion; this is to say that light is brought into focus in front of the retina. Hyperopic astigmatism – like farsighted vision – affects your close vision, and light is brought to focus behind the retina in one or both eyes. A mixed astigmatism is a combination of the two, in each eye. An irregular astigmatism cannot be corrected by eyeglasses, but can be correct by contact lenses. Regular astigmatisms are typically align the meridians perpendicular to each other and cause that football shape.
If you’re looking at your prescription, you can know whether or not you have an astigmatism very easily.
Typically you will see SPH, or your “sphere”; these values are used to know your vision correction needs. However, if you have additional information underneath the CYL (or “cylinder”) and Axis section, you will know that you have an astigmatism. The cylinder lets you know the correction for the astigmatic refractive error; and the value is added or subtracted cylindrically on the meridian depending on your needs. The axis tells you where to put the cylinder. These two values always come together; it is not possible to have a CYL on your prescription without the Axis.
The next time you get your eyes tested, there is no doubt that your doctor will likely give you an astigmatism examine as well. Whether you need single vision lenses, or bifocal glasses, it may be the case that you will also have an astigmatism correction, as well. Correcting an astigmatism shouldn’t cost more than already receiving prescription eyeglasses since the main change is the placement of the lens within the frames. Only if you have a very high astigmatism will the price of your glasses change significantly. However, if you are getting charged more for adding an astigmatism, or just feel that your glasses are too much, you should certainly check out some eye glasses online; you will be sure to find great glasses for a fraction of the price!