Comparing different refractive eye surgeries


Refractive eye surgery has developed enormously in just a few years. Technology has made interventions safer and less invasive, thereby achieving spectacular results in vision improvement.

Before listing the different advantages of each type of intervention, it is necessary to establish the basic underlying concepts. Specifically, refractive surgery is a group of surgical techniques which aim to eliminate or reduce eye defects such as myopia, astigmatism, presbyopia or hyperopia.

When is refractive surgery recommended?

  • When the patient does not suffer from any eye disease.
  • When the patient wants to be free of glasses or contact lenses.
  • When the patient’s ocular refractive error falls within suitable parameters.

It should be noted that no type of refractive surgery is considered universally optimal. The surgeon will examine each patient individually and determine the best procedure on a case by case basis.

Types of refractive eye surgery

  1. PRK (Photorefractive Keratectomy)

Used to correct myopia, astigmatism and hyperopia. It was the very first form of laser eye surgery, and predecessor of the LASIK procedure. Still remains today one of the most frequently performed corrective eye surgery procedures.

PRK shapes the cornea by means of an excimer laser, allowing the light to penetrate the eye and focus it precisely on the retina.

It is an outpatient procedure and is performed in 15 minutes with the help of local anaesthesia. The patient remains awake during the operation, although sometimes an oral sedative is administered.

PRK surgery and LASIK surgery offer very similar results, but post-operative recovery time from the former is slower because the regeneration of epithelial cells needs several days to cover the eye surface.


This technique can be applied to patients with thin corneas.

No risk of corneal layer complications.

The eye intervention is shallower than LASIK.

Lower odds of jeopardising the corneal thickness.


Recovery is slower than LASIK.

It takes more days to notice improved vision.

PRK carries a greater risk of infection, inflammatory episodes, and clouding.

During the initial recovery, the patient may experience more discomfort than if he or she had undergone LASIK.

  1. LASIK (Laser-Assisted in Situ Keratomileusis)

This is today the most common type of laser eye surgery (95% of refractive surgeries) to correct defects such as far-sightedness, near-sightedness and astigmatism.

The technique shapes the cornea so that the eye receives light and focuses it properly in the direction of the retina. The goal is to achieve clearer, better quality vision. This procedure takes 15-20 minutes and the results are visible within 24 hours.


A very quick procedure performed with a local anaesthetic.

Outpatient procedure, so it is possible to return home after the operation.

The results are permanent although there may be regressions.

In a day or two the person can return to work without major inconvenience.

The patient recovers a normalized vision very quickly.

The post-operative period typically unfolds smoothly without any issues.


One of the main side effects of this technique is dry eye. During the operation the nerves responsible for producing the tears are temporarily cut, and some studies have shown that they never fully return to their original density.


FEMTOLASIK technology has a huge advantage over LASIK: the initial cut separating the thin layer of the cornea for treatment is made with a laser rather than a blade. This difference allows for greater safety and precision when performing eye correction.

The recovery time after the operation is two to three days, and the procedure is indicated for treating myopia, hyperopia and astigmatism.


The whole process is done by laser.

Lower increase in intraocular pressure and a less dry eye.

Post-operative recovery is faster, and a more stable healing is obtained overall.

  1. ReLEX Smile Technique

This is done by removing a refractive lens through a tiny incision. Only a small amount of corneal tissue is removed with an incision that varies between 2 and 4 mm.

This procedure is much less invasive than the others and reduces some adverse effects such as dry eye or the risk of infection.

The lenticule and the microincision are made with a femtosecond laser. The difference with FEMTOLASIK technology is that it first uses the femtosecond laser to separate corneal tissue before performing the excimer laser correction.


The micro-incision in the cornea is 90% smaller than in other techniques, so most of the corneal layers remain intact.

It carries much lower risks and is therefore highly recommended for people who practice certain sports.


One of the biggest drawbacks is that no subsequent touch-ups can be performed, and if the desired results are not achieved the patient should resort to PRK, LASIK or FEMTOLASIK.

ReLEX Smile is not indicated for people who suffer from hyperopia.

The cost of this technology is higher than FEMTOLASIK, although both achieve similar results.

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