[Photo-ablation of the cornea with the erbium:YAG laser].
BACKGROUND
Ablation experiments and preclinical studies have shown increased thermal damage and surface roughness after photorefractive keratectomy (PRK) with the erbium: YAG laser.


METHODS
In this study, the thermal damage was investigated on enucleated pig corneas for various laser pulse durations (80 ns to 1 ms) and radiant exposures (0.2-5 J/cm2). The "scanning-spot" method and the fundamental mode photo-ablation were used for spherical corrections. SEM pictures and surface roughness measurements enabled comparison with the morphology after ArF-excimer laser treatment. The surface roughness is one order of magnitude higher compared to the ArF-excimer laser ablation. The surface of the tissue after ablation looks melted.


RESULTS
The thermal damage reduces with increased intensity, and at high intensities the thermal damage results in a constant thickness of > 5 microns.


CONCLUSIONS
Laser-induced melting processes might be the main reason for the high thermal damage and the increased surface roughness after erbium: YAG laser treatment. This leads to the conclusion that the erbium: YAG laser is not a real alternative to the ArF-excimer laser in PRK.
Mrochen
M
M
Augenklinik, Technische Universität, Dresden.
Meinhard
F P
FP
Semshichen
V
V
Funk
R W
RW
Seiler
T
T
D000818:Animals; D003315:Cornea / Q000473:pathology / Q000601:surgery*; D004869:Equipment Safety; D054018:Lasers, Excimer; D008028:Light Coagulation / Q000295:instrumentation*; D008855:Microscopy, Electron, Scanning; D018903:Photorefractive Keratectomy / Q000295:instrumentation*; D013552:Swine
Zur Photoablation der Hornhaut mit dem Erbium: YAG-Laser.