Excimer laser

The excimer laser is a focused light source (electromagnetic radiation) which emits a beam of ultraviolet light (193 nm) with an extremely high specific energy, but with an extremely low penetrating power when used on biological cells. It is able to produce photoablation for the molecular dispersion of extremely fine layers of tissue without damaging adjacent cells.
It is considered the most precise and delicate scalpel in existence today, able to remove extremely fine layers of tissue (fractions of a micron) with a level of consistency and precision which cannot be achieved with any other means.
The ablation of a hundredth of a millimetre of stromal tissue means a correction of one dioptre. With infinitely small corrections, the curvature of the corneal surface of an ametropic eye can be suitably reshaped to the refractive requirements of each individual patient (myopia, hypermetropia, astigmatism).
Ablation reshapes the corneal profile to provide improved eyesight:

  • In cases of myopia it flattens the cornea to make images focus on the retina;
  • In cases of hypermetropia it increases the curvature of the cornea to allow a return to good vision without eyestrain;
  • In cases of astigmatism it makes the cornea more rounded and normal-shaped, to eliminate image distortions;
  • In cases of anisometropia it rebalances the degree of refraction in the two eyes;
  • In cases of presbyopia it restores accommodative force.

In patients with irregularities in the shape of the cornea, it is nowadays possible to carry out personalised laser treatment (CUSTOM CORNEA).
This technique analyses on a point by point basis the shape of the corneal surface (using an aberrometer) and transfers this information to an excimer laser, which is then able to perform an ablation of the corneal surface.
In this way a new smooth surface is obtained which also corrects the refractive defect (both low and high level aberrations are eliminated).
The precise profile created by the laser is guaranteed by a device called an eye-tracker, which allows the light beam to be precisely guided even if the eye moves during treatment.

Laser techniques

The excimer laser can be used on the surface of the cornea or penetrate more deeply inside.
The eye doctor chooses the best technique for each patient according to clinical and diagnostic data, and the pre- and post-operative needs of the patient.
Both eyes can be operated on at the same time.

PRK

This is used for the treatment of mild to moderate refractive errors.
The procedure is carried out on the corneal surface after having removed the outer layer of the cornea (epithelium). This layer, which has both optical and protective functions, regrows very quickly.
Laser photoablation of the corneal surface reshapes the pupil.
The operation requires a topical anaesthetic and is completely painless.
The corneal epithelium regenerates itself in the 48-72 hours after surgery. In this period the patient may feel pain and/or sense a foreign body in the eye which may be eased by using a therapeutic corneal lens and suitable eye drops.

LASEK

This is used for the treatment of mild to moderate refractive errors.
This procedure involves lifting (rather than removing) the corneal epithelium by bathing it in an alcoholic solution.
After laser treatment, the epithelium is replaced onto the corneal stroma, the eye is medicated and a contact lens is inserted.
In most cases, post-operative recovery is shorter than with PRK.

EPILASIK

This is used for the treatment of mild to moderate refractive errors.
This procedure involves lifting (rather than removing) the corneal epithelium. This lifting is carried out using a precision surgical instrument.
After laser treatment, the epithelium is replaced on the corneal stroma, the eye is medicated and a contact lens is inserted.
In most cases, post-operative recovery is shorter than with PRK.