Ametropia, whether it is myopia or hyperopia, is always a refractive error of the eye. This means that light is refracted either in front of or behind the retina. Astigmatism is a special refractive error.

The light emitted by an observed object does not focus on the retina, but is reproduced along a line. If the surface of the cornea is strongly curved, this leads to a higher refraction of light, and if the curvature is low, this leads to a low refraction. The amount of curvature of the cornea is expressed in dioptres.

For a healthy eye, an astigmatism of 0.5 dioptres is considered normal. It is either congenital or develops over time. The cornea is not circular, but elliptical, which creates a blurred image.

In case of astigmatism, either toric or multifocal contact lenses are recommended. 

• They are available in both rigid and flexible versions. They are mainly used for people over 40 years of age who have difficulty seeing correctly between near and distance vision. It is also possible to correct one eye for near vision and the other eye for distance vision.

• Alternating multifocal contact lenses are similar to bifocal glasses. The upper part of the lens is for good distance vision, while the lower part is for close-up vision.

• Simultaneous contact lenses are manufactured in such a way that the distance effect is in the centre of the lens, while the peripheral zone of the lens is responsible for the near effect. Multifocal lenses significantly increase visual performance by correcting astigmatism.

• Hard lenses generally offer better visual performance than soft lenses, but are less likely to be worn because of the foreign body sensation they cause. Nevertheless, vision is more stable in the long term with hard lenses.