EuroEyes Blog
What is an Astigmatism?
A corneal curvature is also called astigmatism, which means that the cornea is not normal but deformed. Astigmatism is a common vision disorder, which is the cause of fuzzy visibility at any distance. Astigmatism often occurs in combination with short-sightedness or farsightedness.
Astigmatism is considered normal in the human eye of up to 0.5 diopters. The deformed cornea is mostly congenital, but in rare cases can develop only with time.
How does an Astigmatism Develop?
Normal Vision
Good vision requires a sharp image being produced on the retina at the back of the eye. The optical system (cornea, crystalline lens and vitreous body) of a normal eye diverts light rays in a way that they land exactly in focus at the point of best vision on the retina, the so-called makula. This diversion of light rays is called refraction. The total refractive power is expressed in diopters (D). The total refractive power is determined on the basis of the different parts of the optical system. When the total refraction is zero diopters, objects will be depicted sharply on the retina.
Astigmatism
Ideally the curvature of the cornea is shaped regularly like the surface of a ball. Astigmatism occurs when the corneal surface is more an irregular shape, more like that of an egg. Instead of gathering in a single point, light focuses at several different points both in front of and behind your retina, causing blurred vision. The light is refracted differently through the different curvatures of the cornea, e.g. vertical light rays are refracted differently than horizontal ones. This results in a distorted image, and a dot may appear as a line. The optical correction is made by changing the refractive power so that the two focal points are shifted exactly onto the retina – basically the same effect as can be achieved with a toric cylindrical lens.
Can Astigmatism be Treated?
Astigmatism can be corrected with glasses, contact lenses or surgery.
Which treatment method is suitable to correct the visual defect depends on its shape and strength. Irregular astigmatism, for example, can not be corrected by regular glasses due to the irregular corneal curvature or an irregularly curved lens.
In order to determine which treatment method is suitable for the patient, a thorough consultation and a detailed examination are always carried out before an intervention.
Surgical correction is an option for treating astigmatism, particularly for cases where glasses or contact lenses are insufficient or undesirable.
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