March 2, 2024

Determining LASIK Candidacy: Unraveling the LASIK Self-Evaluation Test

Laser eye surgery by Lasik technique has 4 steps with lasik self evaluation test. Realizing a corneal flap allows for exposing the deep layers of the corneal tissue (either by a blade or, most often nowadays, by Femtosecond laser).

Corneal flap lift

Remodeling of the surface exposed under this flap using the Excimer Laser resulting in the actual optical correction

Repositioning of the corneal flap

  1. Realization of a corneal flap allowing to expose the deep layers of the corneal tissue

The surgeon on discover vision center for example makes a corneal flap with a diameter of 8 to 11 mm and a thickness of 90 to 200 microns.

This painless surgical procedure, formerly carried out mechanically by a device comprising a blade, is today only carried out by a laser called the Femtosecond Laser:

A laser makes the realization of the corneal flap, therefore without a blade, thanks to the Femtosecond laser (the most recent technique allowing to increase the security and the precision of the result) Since 2007, except in exceptional cases, we no longer cut the cornea with a blade (Microkeratome). We have adopted the technique of all-laser Lasik, which is more effective and, above all, much safer.

The realization of the corneal flap by Femtosecond laser is a major technological advance:

The Femtosecond laser is an ultrafast laser (an impact lasts in the order of a few Femtoseconds, i.e., 10-15 seconds, or a millionth of a billionth of a second) fully controlled by a computer which is at the origin of an essential advance in the technique of Lasik thanks to:

  • increased safety: accidents and serious cutting incidents impossible
  • increased precision: absolute control of the diameter and thickness of the cut
  • increased quality of results: perfectly regular cutting = less astigmatism and induced optical aberrations

More difficult cases can be treated, particularly relatively thin corneas or significant refractive disorders.

The cutting of the cornea by the Femtosecond laser is never totally complete over 360°; the flap produced is always connected to the underlying cornea by a so-called hinge junctional zone.

Realization of the corneal flap by femtosecond laser

  1. Lifting of the corneal flap previously created by the Femtosecond laser

Once the Femtosecond laser has cut the corneal flap, we proceed to lift this flap to expose the corneal stroma on which the Excimer laser beam will be directed, which is responsible for the change in the shape of the cornea and, therefore, the removal of the defect. Of vision.

The corneal flap is lifted.

  1. Remodeling of the surface exposed under this flap using the Excimer Laser, resulting in the actual optical correction

It is then a question of treating the visual defect by the Excimer laser, which is therefore applied in the thickness of the cornea and not as in the surface techniques, on the cornea’s surface. But it is the same Excimer laser used for surface techniques.

Different treatment algorithms are available on the laser; the choice is determined before the intervention by the surgeon to give the best precision and quality of vision postoperatively while respecting the safety criteria.

Typical treatment modes are tissue-sparing modes, aspheric modes, and custom modes.

These treatments use the principle of iris recognition, making it possible to compensate for any movement during surgery (voluntary or involuntary) coupled with an Eye Tracker system.

The use of personalized treatment modes is a step forward in the evolution of Excimer Laser technology, allowing us to provide our patients with:

  • Better postoperative visual acuity
  • Improved quality of vision (less night halos, less visual blurring)
  • Increased safety (no risk of inverting the treatments of 2 patients)

Application of the Excimer laser on the corneal stroma, which eliminates the vision defect by modifying the shape of the cornea

  1. Repositioning of the corneal flap

Once the Excimer laser photo ablation has been performed, the superficial corneal flap is redeployed on the treated area, which it immediately protects.

A dressing lens is placed to protect the flap during the first hours after surgery and to allow you to have pain-free postoperative follow-up.

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