Astigmatism is the technical term which describes the condition of the eye. Although it sounds like a serious disease, it is not. Astigmatism is when the eyeball is oval rather than round, which obviously affects the focus of an object on the retina. A common analogy is comparing a basketball to a football. The eye with astigmatism looks more like a football. Obviously not that dramatic in shape, but it is a good analogy to illustrate the difference. This vision problem causes objects to appear blurred and distorted. Images have a shadow beside it almost seeming doubled. It is in fact a very common problem affecting most people at one time or another, and it can occur with both nearsightedness and farsightedness. Rest assured, astigmatism can be corrected very easily by wearing glasses, contact lenses or by surgery.
How Astigmatism is Diagnosed
First signs that you may notice if you have astigmatism is that your vision is blurry at a distance as well as close up. You may feel tired after reading and may see letters and words as slanted. Squinting or tilting your head may improve the distorted vision if it is caused by astigmatism. When you go for your regular eye checkup the doctor will check for nearsightedness and farsightedness. This is when you look through a machine and have to say which image is better, one or two. This test also looks for astigmatism. A manual or automated keratometer may be used to measure the curvature of the cornea which will clearly show astigmatism in any basic eye examination. A corneal topographer may be used to make the diagnosis as well. This instrument creates a color-coded map of the cornea, similar to that used to make a topographical map of mountains. Steeper areas are indicated in red and flatter areas in blue and will clearly show any astigmatism bulge, and the severity of it. A wavefront aberrometer may also be used to give the optometrist a clear diagnosis of the wavefront errors, or aberrations of the eye. You can tell whether you have astigmatism by looking at your eye prescription. The box 'Cyl' will show the power you need to correct astigmatism, if you have one. Axis tells the manufacturer of the glasses or contact lenses where the astigmatism is and where the power should be to correct it.
Causes of Astigmatism
Astigmatism is caused when the cornea of the eye becomes oblong or oval rather than spherical. A cornea which has astigmatism has two curves, a flat curve and a steep curve so light is focused at two points instead of more clearly at just one point. Astigmatism may cause one point of focus to be in front of the retina and the other behind, causing images to be slightly blurred. There is another type of astigmatism called 'lenticular astigmatism'. This is caused by an irregularly shaped crystalline lens, but the results are the same - a blurry image on the retina.
Problems with Astigmatism
Astigmatism is the most common cause for discomfort when wearing glasses. It can take some time for people to get used to new glasses. It can cause slight disorientation, particularly on steps and staircases. Contact lenses can minimize the discomfort, making them a better option for some patients with astigmatism, particularly if there is a large amount of astigmatism.
Treatment for Astigmatism
Astigmatism can easily be corrected with glasses, contact lenses or surgery. Glasses are the most commonly used treatment and when carefully adjusted they work well. An anti-reflective coating may also help decrease unwanted glare and halos from bright lights which are sometimes a problem with astigmatism. Contact Lenses may be preferred to correct astigmatism. In this case they are called Toric contact lenses. They are designed to stay in one place on the eye to correct the curve rather than to rotate. Patients with a large amount of astigmatism may find that rigid gas permeable contact lenses are the most effective treatment. New hybrid lenses have been developed which have a rigid center and a soft skirt. They combine the benefits of a rigid lens with the comfort of a soft lens. Keep the eyes moist by using plenty of eyedrops. Surgery is an increasingly popular choice for correcting astigmatism. Wavefront Lasik is the most common procedure and uses 3-dimensional measurements of the eye to guide the laser to reshape the front part of the eye, also known as the cornea.
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