Astigmatism is a visual defect that causes difficulties in seeing fine details of both far and near objects. The higher the degree of astigmatism is, the less the clearness of the images on the retina.
The vision of a person affected by astigmatism is very particular: he does not have a blurry vision as a myopic has, but he has a double vision, as if there were two different overlapping images (real situation). Hence, astigmatism causes a partial lack of the capacity to focus objects that, in case of high degree of astigmatism, can look distorted or stretched: a circle looks as an oval, a cross is seen with one of the two branches clearer than the other one.
Astigmatism can manifest in a simple form, when the eye has a pure disorder, not combined with others, or in a mixed form, combined with myopia or hyperopia.
It is possible to correct permanently both these forms of astigmatism undergoing treatments that use the laser to reshape the curvature of the cornea.
The femtosecond laser treatment (intrastromal keratomileusis) is not carried out on the surface of the cornea, but in deeper layers after the creation of a flap and can be the solution also for an high degree ofastigmatism.
The PRK treatment (photorefractive keratectomy) is recommended only for low degrees of astigmatism.
To correct high astigmatism, where the laser cannot be used, the implant of a toric phakic lens in addition to the natural one, or the implant of an artificial crystalline lens in place of the natural one can be suggested.