Laser refractive surgery to correct refractive defects

Laser refractive surgery is used to correct refractive defects of myopia, hyperopia and astigmatism, which force the patient to wear glasses or contact lenses. We have Dr. Juan Lillo Sopena, Ophthalmologist and Expert in Laser Refractive Surgery at Dr. Lillo Ophthalmology Center, to learn about laser eye treatments.

Laser refractive surgery to improve eyesight

Laser refractive surgery is a surgical procedure to correct refractive defects (myopia, hyperopia and astigmatism), which force the patient to wear glasses or contact lenses in order to see properly. Therefore, it is a surgery indicated in myopic patients, hyperopic patients, and in patients affected by the pathology of astigmatism, either isolated or associated to the previous defects.

In all these refractive defects, what happens is that the curvature of the cornea, which is the most important lens of the eyeball, does not present the appropriate characteristics to focus images sharply on the retina.

Eye laser treatments: refractive surgery

This type of surgery is indicated for patients over 18 to 20 years of age and who present a stable refractive defect of at least 12 to 18 months. It is performed with the help of the Excimer laser, modifying this curvature so that images are sharply focused.

This surgery is usually indicated below the age of 40-45 years, since from this age presbyopia or eyestrain will appear, so that the patient will need glasses for near vision. Thereafter, there are other surgical procedures to correct refractive defects, while also correcting presbyopia.

LASIK technique: Excimer laser to correct the cornea

The most commonly used surgical procedure is the LASIK technique, which has more than 20 years of experience, and which has been perfected since its appearance. Basically, it consists of performing, at first, a non-complete cut of a more superficial corneal layer, about 100/120 microns thick. Next, and with the help of the Excimer laser, we ablate the corneal bed (we have previously programmed the patient’s diopters in the laser, which will have to be corrected in the refractive surgery procedure with laser eye) to carve the surface, so that we modify its curvature, and thus eliminate the refractive defect that is present.

Once the corneal ablation is done with the laser, we will proceed to reposition the superficial corneal lamella that we had carved, and with this last part of the procedure we would conclude the intervention. There are currently two systems for cutting this superficial corneal lamella. The traditional one is performed with the help of a microkeratome, which is an instrument that cuts this lenticule mechanically.

Femtosecond laser for refractive surgery

The other method, which we have been practicing for some years now, is with the help of the Femtosecond laser. So it would be this laser that would cut this superficial lenticule. This method can be useful in some patients with corneal characteristics that would make it difficult to cut with the microkeratome.

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This surgery is performed under topical anesthesia (drops), so that the patient will be conscious, and at certain times must fix the gaze as indicated by the surgeon. It is a painless procedure, although it can be a little uncomfortable, so it is important that the patient is relaxed, so that the procedure is safer.

Other laser eye treatments to correct refractive defects

There are other laser procedures to treat minor refractive defects, or in patients in whom it would not be indicated to cut the superficial corneal lamella. These are PRK and LASEK.

In these procedures we will not cut the superficial corneal lamina, but we will directly ablate the corneal surface with the Excimer laser, previously de-epithelializing it. The limitation of this technique is that it does not allow us to correct a high number of diopters, and the postoperative recovery will be longer.

In this surgery, both eyes are usually operated on at the same time. The duration of each procedure is about 10 minutes, including preparations. After surgery, it is usual that after the first few hours, the patient’s vision is blurred and there is little discomfort. Usually, the next day the discomfort is minimal and visual acuity is usually very good, reaching 100% in most cases.

If PRK or LASEK has been performed, this period is extended for several days.

The results of this surgery are very satisfactory, so that the patient in the vast majority of cases, will have a visual acuity equal to the one he/she had before with the use of glasses or contact lenses. It is not a procedure to gain visual acuity, that is, if a patient had a visual acuity of 70% before surgery, his vision after surgery will be the same, with the difference of not needing optical correction.

The possibility of correcting the refractive defect with laser surgery will depend on the corneal thickness of the patient, so that the greater the corneal thickness, the greater the number of diopters that can be corrected. In any case, it is not advisable to correct more than 7-8 diopters with LASIK. When the refractive defect is high and the corneal thickness does not allow us to perform laser safely, we have the option of correcting it by other techniques, which would consist in the introduction of an intraocular lens between the iris and the crystalline lens (ICL).