{"id":2152,"date":"2020-03-30T19:54:34","date_gmt":"2020-03-30T19:54:34","guid":{"rendered":"https:\/\/imedicalsociety.org\/?p=2152"},"modified":"2020-03-30T19:54:34","modified_gmt":"2020-03-30T19:54:34","slug":"astigmatism","status":"publish","type":"post","link":"https:\/\/imedicalsociety.org\/astigmatism\/","title":{"rendered":"Astigmatism: signs, diagnosis, treatment"},"content":{"rendered":"
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Astigmatism<\/strong><\/h1>\n<\/div>\n
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In astigmatism<\/strong>, an irregular shape of the cornea of the eye causes the incident light to be imaged distorted on the retina (Source<\/a>). As a result, the patients affected with this condition have their vision blurred (Source<\/a>). There are many causes of astigmatism (Sources<\/a>), but it is often congenital (Source<\/a>). It can often be corrected with special visual aids (Source<\/a>) of different types (Source<\/a>). Read more about astigmatism.<\/p>\n<\/div>\n<\/div>\n

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ICD codes for this condition are H18 <\/span>H52<\/span><\/span><\/p>\n

ICD codes are internationally valid codes for medical diagnoses. They can be found, for example, in doctors’ letters or on certificates of incapacity to work.<\/div>\n<\/div>\n<\/div>\n<\/section>\n<\/div>\n
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\"astigmatism\"<\/div>\n
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Description<\/strong><\/h2>\n

The cornea is the foremost part of the eyeball that lies in front of the pupil. It is slightly oval in shape, slightly smaller than a small coin, and about half a millimeter thick (Source<\/a>). Since it rests on the round eyeball, it is itself spherically curved, much like a contact lens.<\/p>\n

What is astigmatism?<\/h3>\n

We speak of astigmatism (inaccurately: “corneal curvature”) when the cornea is not evenly curved. This anomaly is called “astigmatism”.<\/p>\n

Normally, the cornea, together with the lens of the eye, ensures that the parallel incident rays of light are bundled and focused on a single point on the retina (focal point). This enables sharp vision.<\/p>\n

In astigmatism, however, the cornea is unevenly curved, which means that the light cannot be properly focused. In some places, incoming light rays are bundled more strongly than in others. As a result, they do not merge into a single point on the retina: no single clear point is imaged on the retina – vision is blurred.<\/p>\n

What types of astigmatism are there?<\/h3>\n

In regular astigmatism, incident light rays are imaged on vertical focal lines (“rod”). This form of astigmatism can be further subdivided, but it is mainly relevant for the optician to be able to produce a perfectly fitting visual aid.<\/p>\n

Irregular is a curvature of the cornea whose optical planes are not perpendicular to each other. To put it more simply: While there is still a certain order in regular astigmatism, an irregular astigmatism sometimes has no recognizable system at all. In extreme forms, such as corneal scarring, the light is deflected in various directions so that there are hardly any focal lines left. The treatment of irregular astigmatism is therefore more difficult.<\/p>\n

Astigmatism can also be judged by where the focal lines lie in relation to the retina. Often one is in the retinal plane, but the other is in front of it (astigmatism myopicus simplex) or behind it (astigmatism hyperopicus simplex). There can also be a focal line in front of it and the other one behind it (astigmatism mixtus). Sometimes there is farsightedness or nearsightedness (hyperopia or myopia) in addition to astigmatism: “Astigmatism compositus” is what the specialist calls this.<\/p>\n

\u00a0Corneal Curvature Symptoms<\/span><\/h2>\n<\/section>\n
A corneal curvature is only noticeable if it is more pronounced. Slight forms of this visual defect, on the other hand, have hardly any noticeable effects for those affected and are found in many people. However, a pronounced astigmatism shows the following symptoms:<\/p>\n