It called astigmatism to a disorder of vision which occurs when the lens and the cornea have irregular curvature on its surface. In this way, a refraction is produced that is different between the eye meridians, making precise focusing impossible.
It should be remembered that the light focused on the retina passes through the cornea, which works like a lens. If the corneal surface does not have a regular and symmetrical curvature, astigmatism is generated. The irregularity of the curvature can also appear in the lens (the ocular structure behind the iris and in front of the vitreous humor, which acts as a biconvex lens).
According to DigoPaul, astigmatism is usually congenital: it is already suffered from the moment of birth. In milder cases, it may not manifest or cause symptoms. Instead, when the astigmatism is marked, the person sees the objects distorted and blurred. Because the eye seeks to reverse the effect, it generates an overstrain in the muscles that can cause dizziness and headache.
To treat astigmatism, which usually appears together with myopia (a disorder that occurs when light rays that come from a considerable distance establish focus in a site before the retina), you can resort to laser surgery, by use of glasses with cylindrical lenses or the use of contact lenses.
In addition to all the above, we can not ignore other series of interesting data about astigmatism, such as the following:
-It usually appears early. And it is considered that Hispanic and Asian children are more likely to suffer.
-It is possible to diagnose through one of the routine tests that are carried out in order to know the state of the sight.
-It must be established that it is believed that around 26% of the population has this refractive defect. Moreover, it is even established that approximately 80% of those who have myopia also have the aforementioned.
-Contact lenses are the main tool used to carry out the “fight” against astigmatism. However, we must indicate that there are those who prefer to opt for the use of surgery. In this case, it is necessary to know that up to six diopters are operable with this mechanism.
It is important to mention that astigmatism can be classified as high, medium or low and that it can be defined as irregular or regular depending on the arrangement of the main meridians. In the case of regular astigmatism, a distinction is made between simple astigmatism (simple hypermetropic or simple myopic) or compound (compound hypermetropic, compound myopic or mixed). There is also the oblique astigmatism, the reverse astigmatism and direct astigmatism according to how develops refraction.
Although we have mentioned many types of astigmatism, it is usual for three different classes to be taken into account:
-The myopic, which occurs when one or both meridians of the eye tend to focus as myopic.
-The hypermetropic, which takes place at the moment in which one or both of the aforementioned meridians proceed to focus as hyperopic.
-Mixed astigmatism, which is the type characterized by the fact that one of the meridians proceeds to focus as short-sighted and the other as hyperopic.