[Femto-LASIK: the state-of-the-art method for the correction of a visual defect
Femto-LASIK is the most important procedure used today to correct a visual defect by surgical means. In the hands of an experienced eye surgeon, it is an extremely precise and safe method of treatment.
With the Femto-LASIK method it became possible for the first time to perform a treatment entirely without using a mechanical device (microkeratome). The lamella of cornea (flap) is cut out using a so-called femtosecond laser, which increases the precision and safety of the procedure markedly.
The following step of the operation, the actual correction of the visual defect with the Excimer laser, is the same as with the LASIK method using a microkeratome.
1. "Laser replaces blade": preparation of the corneal flap with the femtosecond laser
A suction ring is attached on the eye. The eye is made insensitive to pain with eye drops,
while the eyelids are maintained open by a eyelid holder to avoid involuntary closing.
A contact glass is then set into the suction ring: this permits precise and safe targeting of the
computer-controlled laser beam to the area to be cut.
These high-precision elements (suction ring and contact glass) are expensive, because,
for hygiene reasons, and also to attain the best possible precision, they are used only once.
Preparation of the corneal flap: in the first step, the flap is excised by the cumulative effect of thousands of laser pulses in one plane of corneal tissue.
Control: the cutting of the flap is monitored on screen via an operation microscope (in the punctuated area the laser has already been at work).
2. Uncovering the treatment plane
Once the corneal flap is prepared as planned, the suction ring is removed and the flap is
carefully flapped back with a fine instrument.
3. Ablation of corneal tissue by Excimer laser to correct the visual defect
As in classical LASIK, the exposed corneal tissue is shaped with the Excimer laser so that the visual defect is corrected.
The corneal ablation is performed according to the selected mode (customized Lasik, special laser programs)
The active eye-tracking system ensures that the laser pulses hit the predetermined
target of the cornea even in case of involuntary eye movements of the patient.
Control of treatment during the operation: an online pachymeter (device measuring thickness)
monitors the preparation of the corneal flap to a precision of a thousandth of a millimeter,
without direct contact and under the control of special software, as well as the ablation of
corneal tissue by the Excimer laser.
The attending physician therefore has a supplementary means to verify that the treatment progresses according to plan.
4. Conclusion of the treatment
Once the treatment with the Excimer laser is completed, the corneal flap is put back into place. It reattaches spontaneously to the underlying corneal layers, without suture. The corneal flap acts as a natural organic wound dressing and exerts a positive influence on the healing process.
As a rule the patient does not feel any pain. The external corneal layer (the epithelium) which was partially sectioned, regenerates completely within a few days and closes the wound.
How does the femtosecond laser work?
Contrary to the Excimer laser, the radiation energy is not released on the surface of the cornea but inside the cornea, at a depth previously defined with a precision of a millionth of a millimeter. At the focal point of the radiation, the tissue is disrupted by so-called photodisruption, whereas outside of the targeted area it remains untouched. The corneal flap is formed by the cumulative effect of thousands of laser impulsions along a given plane, within a few seconds.
Properties and advantages of the Femto-LASIK
The advantage of the Femto-LASIK method resides in the fact that there is no wound at the surface of the cornea, and therefore no pain due to the wound-healing process after the operation. You will be able to leave the eye laser center after 1 to 2 hours, without an eye bandage. Your visual acuity will already be good enough for you to be able to travel by public transport – but we still recommend that you have somebody at hand to accompany you on your way home. Also, you should not drive on the first day.
The Femto-LASIK method permits to obtain precise and lasting corrections of myopia to ca. -10 diopters and hyperopia up to +5 diopters, and at the same time of an astigmatism, if present, of up to 5 diopters, depending on the thickness of the cornea.
LASIK was introduced in Switzerland in 1994 by VEDIS. Our experience with this operating technique is therefore considerable, and the results we obtain with LASIK are indeed excellent. The introduction of the Femto-LASIK technique is a further improvement of the method.
Properties of the LASIK method
• Very high precision and stability of the result obtained
• Correction of the visual defect inside the cornea
• No pain during the operation
• Very short recovery time, a few hours to days
• Further later corrections are possible
