Excimer laser is used in refractive surgery for PRK/LASEK, LASIK and FemtoLASIK techniques.
LASER refractive surgery is a surgical treatment which was developed in order to correct diopters. The surgery is performed at both eyes during the same session. All laser diopters reduction techniques result in the corneal reshaping with the purpose of modifying the corneal refractive power, thus obtaining the correction of the desired diopter.
The fundamental difference between the existent techniques is represented by the way the cornea is “prepared” before laser treatment.
Excimer laser is used for refractive surgery since 1980s, starting from the first refractive surgery generation (PRK/LASEK) and continuing with the second refractive surgery generation (LASIK, FemtoLASIK).
PRK and LASEK
PRK was the first laser technique, that does not require cutting of the cornea. The technique is based on the property of the corneal epithelium (the first layer of the cornea) to regenerate naturally and consists in the partial removal of this layer, by using an alcoholic solution. After this layer is removed, the cornea is reshaped by means of excimer laser. In the end, a therapeutic contact lens is applied as a bandage. The re-epithelialization occurs within the next 3-4 days after the surgery when the symptoms can be unpleasant, depending on the tolerance of every person, from blurry vision, tearing, photophobia to burning sensation, pain. The advantage of this technique is given by the fact that it does not require the cutting of the cornea, the disadvantages are represented by the slow recovery, the discomfort emphasized during the first 24 and 72 hours after the surgery and by the high degree of regression, compared to more advanced laser surgery techniques.
LASEK technique is very similar to PRK technique. Both entail the corneal deepithelialization instead of creating a flap which includes the stroma layer. The difference between the 2 techniques consists in the conservation of the epithelium in case of LASEK. Initially it was believed that by maintaining the epithelium, the healing process will be faster. However, the practice has proven the opposite, that the recovery is slower. In case of PRK technique, the eyes are more relaxed immediately after the surgery, and the recovery term is shorter.
LASIK si FemtoLASIK
During the performance of LASIK, a flap is created in the cornea using a tool called microkeratome. In case of FemtoLASIK technique the flap is cut by means of VisuMax Carl Zeiss Meditec femtosecond laser, a high precision femtosecond laser. Then, the excimer laser is applied for corneal reshaping.
The thickness of the corneal flap can vary, but it is usually about 100 microns. A non-slatted section is left during corneal flap creation, which is called hinge. After the flap is created, it is removed, thus the excimer laser is applied on remaining exposed corneal stroma. Following the application of the excimer laser, the cornea is washed and the flap is repositioned. The flap also represents a postsurgical “bandage” thus reducing the symptoms during healing process. The flap adhesion to the remaining corneal stroma is usually good, no sutures being required.
In some cases, LASIK is contra-indicated: if one’s have thin cornea, if one’s suffer from dry eye syndrome, if one’s job involves physical effort or if carrying out activities with risk of strong or repeated trauma around the eyes (boxers, weightlifters, karatists etc.). In these cases, other techniques can be performed: PRK or SMILE depending on the dioters.
FemtoLASIK technique is similar to LASIK, the difference consists of the way the corneal flap is created. For its performance, VisuMax femtosecond laser is used, which provides an accuracy of less than one micron. The flap created with this femtosecond laser respect the natural curvature of the eye and has vertical edges, thus granting a high stability of the cornea, after the intervention.
LASIK, FemtoLASIK, PRK, LASEK
LASIK affects more the structure of the cornea, but provides a high comfort, fast visual recovery and greater diopters stability than PRK/LASEK. FemtoLASIK is an evolution of LASIK technique. FemtoLASIK advantages over LASIK are related with the postoperative comfort, and in addition, it provides a higher stability of the cornea after the surgery, due to the way the flap is created. PRK technique is a safe technique, but it involves a higher operator discomfort depending on each individual, but it can be performed even in cases of thinner corneas.
In our clinic we perform diopters reduction interventions with Carl Zeiss Meditec technology, by means of PRK and FemtoLASIK techniques.
We only perform FemtoLASIK technique, where the flap is cut by means of the most powerful femtosecond laser of the moment, VisuMax Carl Zeiss Meditec, due to the fact it provides a higher corneal stability after the surgery.
As an evolution of the presented techniques, we mention ReLEx SMILE technique, the third generation of refractive surgery and also the most modern and safest, which took over the advantages of these techniques, but removed their disadvantages. In case of ReLEx SMILE only the VisuMax femtosecond laser with SMILE platform is used and high myopia, of up to -10 diopters and myopic astigmatism up to -5 diopters are corrected. Visit page SMILE and page femtolaser VisuMax for further details.
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