Diffractive smoothing of excimer laser ablation using a defocused beam.
OBJECTIVE
To determine if excimer laser myopic ablation with a defocused laser image produces a smoother ablation profile than does focused laser light.


METHODS
An ArF excimer laser was used to ablate a 5.00-diopter myopic correction in test blocks using both a contracting and expanding iris aperture. Defocused ablation was performed using a contracting iris aperture by translating the target away from the laser source. A confocal laser scanning microscope was used to analyze the surface smoothness at 55x and 275x magnifications.


RESULTS
The confocal laser scanning micrographs revealed a series of sharply demarcated concentric ridges in the focused ablation, and less prominent, slightly wavy lines in the defocused ablation performed with a contracting aperture. The focused ablation with an expanding aperture also created concentric ridges toward the periphery, but with slightly smoother edges.
Krueger
R R
RR
Doheny Eye Institute, University of Southern California School of Medicine, Los Angeles.
Wang
X W
XW
Rudisill
M
M
Trokel
S L
SL
McDonnell
P J
PJ
D007834:Lasers; D020366:Methylmethacrylate; D008768:Methylmethacrylates / Q000528:radiation effects*; D008853:Microscopy
D008768:Methylmethacrylates; D020366:Methylmethacrylate