1Heisterkamp A., 2Mamom T., 2Drommer W., 3Kermani O., 1Lubatschowski H., 4Ertmer W.

1Laser Zentrum Hannover, Hollerithallee 8, 30419 Hannover, 2Institut für Pathologie, Tierärztliche Hochschule Hannover, 3Laserforum Köln, 4Institut für Quantenoptik, Universität Hannover

Objective: Aim of this study was to determine the achievable cutting quality and woundhealing-effects during application of ultrashort laser pulses in refractive surgery in living animal.
Material and Methods: The fs-laser pulses were delivered by a Titanium- Sapphire-Laser at a wavelength of 780 nm and pulse duration of 160 fs. The used pulse energies were 0.8 µJ at repetition rates of 3 kHz. The laser light was focussed into the cornea to a spot size of 4 µm. The system allowed creation of "flaps" and lenticules with diameters of up to 6 mm using a flying-spot procedure. Specimen used in this experiments were freshly enucleated porcine eyeglobes and 3 living New Zealand white rabbits. The results were analysed by histo-pathological techniques. Woundhealing was studied up to 2 weeks post-op.
Results: The achievable accuracy by using fs-pulses for intrastromal cutting is in the µm-range. With shorter pulse duration the accuracy was even higher, resulting in a sub-µm-accuracy at 160 fs, the thermal damage was estimated to be well below 1 µm, too. Moreover, tissue alteration along the laser beam axis near the focus area inside the cornea was found. This tissue alteration is due to non-linear interaction processes of the laser radiation with the tissue.
Conclusion: The cutting precision and the woundhealing during the first two weeks post-op are comparable to what is known from excimer-LASIK. Additional side effects based on nonlinear processes were observed.

Copyright © Deutsche Ophthalmologische Gesellschaft, 2001. All rights reserved.

Last updated: 

Webdesign: SPALLEK.COM