Refractive defects are corrected by excimer laser treatment. This laser is able to reshape the contour of the cornea, by ablation of the cornea, in an extremely precise and gentle manner. In practical terms, the laser vaporizes a thin layer of the cornea, changing its power and thus allowing the refractive defect, whether myopia, astigmatism or hyperopia, to be corrected. There are several laser techniques:

• PRK. PRK (photorefractive keratectomy) is the technique that involves, in its most common version, the prior removal of the corneal epithelium in order to expose the corneal stroma for laser treatment. The excimer laser can now perform ablation (removal) of a thin layer of the stroma so as to give the cornea a new profile and thus achieve correction of the visual defect. At the end of the surgery, a contact lens is applied to protect the cornea, which should be worn for 5-7 days. Corneal healing will occur within a few days, with the disappearance of postoperative discomfort such as foreign body sensation, photophobia, and tearing.  Full visual recovery will occur after a few weeks.

• FemtoLASIK. In this technique a first laser, called a femtosecond laser,  Sculpts a thin flap of cornea about 100 microns thick. The flap, also called a flap, is lifted up like the page of a book, and the excimer laser provide ablation of the corneal tissue as in PRK, but slightly deeper. The big advantage of this technique is that the flap or flap is repositioned at the end of the procedure, protecting the newly treated cornea, without the need for contact lens fitting, with the epithelium intact. Healing is much faster than PRK with prompt visual recovery and minimal discomfort for only a few hours, or at most one or two days.

When is PRK done? When is FemtoLASIK best?

There is no single answer. In general, it can be said that the results of the two techniques are equivalent. Currently, FemtoLASIK is the technique of choice for the majority of patients with varying degrees of myopia given the fast visual recovery and limited postoperative discomfort, but it is particularly indicated in cases of astigmatism and hypermetropia. PRK is preferred in patients who have particularly thin corneas and in those who participate in contact sports, such as boxing or martial arts.

When correction with laser, and when with ICL?

The decision on which technique is best depends on the individual case. In general, ICL implantation is the solution of choice in cases of high myopia, when excimer laser ablation would result in excessive tissue removal and therefore be dangerous to the integrity of the cornea. Similarly, ICL implantation is also indicated in cases of more moderate myopia but with corneal thickness too thin to withstand excimer laser treatment.

What examinations are needed to assess operability?

Suitability for treatment goes through the medical history, that is, the collection of general and specialized medical history, which must assess familiarity for eye diseases,  stability of the visual defect, and the presence of drug allergies. The subsequent objective examination assesses the extent of the visual defect (refraction), both in miosis and cycloplegia, to decide what the extent of treatment will be, and excludes the presence of pathologies such as corneal ectasia, especially keratoconus, which contraindicate laser treatment. The key examination in this regard is corneal tomography-topography. The examination allows the evaluation of parameters that are fundamental for the correct treatment setting, such as corneal thickness (pachymetry), corneal size, and corneal shape. Corneal tomography allows determination of the curvature of both the anterior and posterior faces of the cornea, enabling determination of any abnormalities such as those induced by keratoconus.

Tomography, in addition to excimer laser treatment, is also essential in the case of ICL implantation. For such an implant, in fact, the determination of the depth of the anterior chamber as well as the size of the cornea is necessary.