In refractive eye surgery for the purpose of treating sight defects by photoablation of the cornea, argon-fluoride excimer lasers, which emit ultraviolet light with a wavelength of 193 nm, are customarily employed at present. Since the cornea exhibits a high absorption within this wavelength range, corneal tissue can be resected precisely with minimal stressing of adjacent tissue layers. The resection depth—that is to say, the thickness of the layer of corneal tissue resected by the laser—is controlled in this case by appropriate control of the pulse energy, in which connection the monitoring of the pulse energy has to be undertaken in such a way that harm to the patient by virtue of changes in the tissue adjacent to the corneal tissue to be resected is reliably avoided.
Excimer-laser systems that are used at the present time operate with repetition-rates from 200 Hz to 750 Hz. However, an increase in the laser frequency would enable a shortening of the duration of treatment, by virtue of which complications and the dehydration of the cornea during the operation could be minimised. Consequently efforts are being made in refractive eye surgery to bring excimer-laser systems into operation having an increased repetition-rate of up to 1050 Hz. However, the elevated frequency of the laser systems has to be taken into account in the control of the pulse energy, since otherwise damage to the eye being treated might not be reliably ruled out.