How does the Excimer laser work?
The excimer laser has been used for laser vision correction since 1987. It produces a beam of ultraviolet laser light whose energy is immediately absorbed when it encounters the water-containing tissue of the cornea. The excimer laser literally vaporizes the corneal surface without causing any surrounding thermal injury. Thus, the excimer laser can precisely sculpt the corneal surface and change its contour (= photoablation).

The VISX STAR S4 IR Excimer Laser -
a state-of-the-art excimer laser system
This modern laser system includes:

(1) Iris Registration,
(2) Variable Spot Scanning,
(3) Variable Repetition Rate,
(4) ActiveTrack 3D Eye Tracking and
(5) Integration of data collected by the
     WaveScan wavefront system.

Iris Registration (IR)
Iris registration is an alignment method that provides greater accuracy. An advancement over standard alignment practices, iris registration achieves alignment by automatically linking a patient's diagnostic information with the laser treatment. Iris registration then centers the treatment correctly, independent of changes in the pupil center from measurement to treatment. This process also allows for instant re-registration in the event of intraoperative cyclotorsional movement.

Variable Spot Scanning and Variable Repetition Rate
These technologies ensure a precise ablation. By continually changing the size and placement of the beam. Variable Repetition Rate technology provides an accurate reconstruction of the wavefront profile, smoother ablation profiles and faster treatment times. Variable spot scanning and variable repetition rate also minimize thermal effects and provide potentially better overall outcomes, including night vision quality.