An Automatic Fluence Level Adjustment (AFLA). The goal of AFLA is to achieve perfect smoothness with high ablation speed. This has been developed to ensure an ideally balanced ratio between the total number of laser pulses and the energy delivered. The result is that approximately 80% of the laser ablation is performed with a high fluence value, while low fluence is used for the remaining 20%. The ideal smoothing of the surface is achieved by adding low fluence pulses at the end of the treatment.

The SCHWIND AMARIS laser uses a small spot size of 0.54 mm and a Super-Gaussian beam profile. The improved spot overlap matrix is designed to provide a precise reproduction of the calculated ablation volume avoiding vacancies and corneal roughness.

The small spot size allows the laser to perform sophisticated ablation profiles with a high-speed ablation time. This reduces the likelihood of significant stromal bed dehydration during a large correction. The 750-Hz laser system at a 6-mm optical zone corrects 1.0 diopter (D) in 1.5 seconds versus 1.0 D in 2 seconds for the 500-Hz laser system.

The SCHWIND AMARIS laser systems work with an Intelligent Thermal Effect Control (ITEC)¹ that reduces the likelihood of damage to surrounding corneal tissue, even at the extremely high ablation speed. The ITEC algorithm ensures that the temperature rise of the cornea is <5° and significantly <40°, which is considered critical for corneal tissue denaturation.

The laser systems have an active tracker to monitor the position of the eye 1,050 times/second with an average latency of about 1.6 ms. The total reaction time of the AMARIS is typically <3 ms. The AMARIS 750S laser system continuously tracks and actively compensates for eye movements including dynamic cyclotorsion (DCC), which is the rotating movement of the eye during the laser treatment. The laser detects both the pupil and the limbus. The limbus is used as a reference for ablation because its diameter is stable, meaning that the original ablation center is maintained throughout the treatment. The point selected as the center of the ablation is the same throughout the treatment because the laser system tracks the pupil in relation to the limbus.

The illumination is automatically adjusted to maintain the pupil diameter at the same size at the beginning of the treatment as it was at the preoperative examination when the diagnostic data were obtained.

Real-time pachymetry provides information about the corneal thickness throughout the entire duration of the treatment. The changes are measured and displayed on the treatment screen. The measurements can be taken before the preparation and after lifting of the flap, as well as during and after the laser treatment. This
ensures that the surgeon knows exactly how much tissue has been ablated at all times and the thickness of the remaining cornea. Real-time pachymetry allows the surgeon to change the surgical plan intraoperatively if the stromal bed is thinner than expected. Pachymetric data can be printed and saved for future reference in the event that retreatment surgery is needed in the future.

The microscope for the SCHWIND AMARIS laser delivers good contrast, true color brilliance, and good depth of focus. The diagnostic slit lamp for flap checking is compactly designed and can be moved around two axes across the entire working area.

With the AMARIS laser systems the laser beam is guided through a completely enclosed beam path in a vacuum. No disturbing elements can impair the quality of the laser beam, and there is no deviation of results to be expected as, for example, could occur with the use of nitrogen (Fig. 9.1).