astigmatism

Should I worry about Astigmatism?



The word “astigmatism” is used so much in the ophthalmic world now that most people have used the term when discussing their eye health with their doctor. The word “astigmatism” comes from the Greek a- meaning “without”, and -stigma, meaning “a point”. In technical ocular terms, astigmatism means that instead of there being one point of focus in the eye, there are two different foci. In other words, light merges not on to a singular point, but on two different points. This is experienced in the real world by blurred, hazy vision, and can sometimes lead to eye strain or headaches if not corrected with either spectacles or contact lenses.

Astigmatism is not a disease. In fact, most people, greater than 90%, have some degree of astigmatism. Astigmatism is also referred to, in the ophthalmic world, as cylinder.  Astigmatism occurs when the cornea, the clear front surface of the eye like a watch crystal, is not perfectly round.  The real-world example we often use to explain astigmatism is the difference between a basketball and a football.  If you cut a basketball in half you get a nice round half of a sphere.  That is the shape of a cornea without astigmatism.  If you cut a football in half lengthwise you are left with a curved surface that is not perfectly round.  It has a steeper curvature on one side and a flatter curve on the other side.  This is an exaggerated example of what a cornea with astigmatism looks like. The degree of astigmatism and the angle which it occurs is very different from person to the next.  Therefore, two eyeglass prescriptions are rarely the same. There are an infinite number of shapes the eye can take.

Most astigmatism is “regular astigmatism,” where the two different curvatures to the eye lie 90 degrees apart from one another. Some eye diseases or surgeries of the eye can induce “irregular astigmatism,” where the curvatures are in several different places on the eye’s surface, and often the curvatures are vastly different, leading to a high amount of astigmatism. Regular astigmatism is treated with glasses, contact lenses, or refractive surgery (PRK or Lasik). Irregular astigmatism usually cannot be treated with these conventional methods, such as the eye disease keratoconus. In these circumstances, special contact lenses are needed to treat the condition.

The next time you hear that either you or a loved one has astigmatism, fear not. It is easily corrected, and although it can cause your vision to be blurry it rarely causes any permanent damage to the health of your eyes. If you experience blurred vision, headaches, or eye strain, having a complete eye exam may lead to a diagnosis and treatment of this easily dealt with condition.

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