Dynamics of ablation plume particles generated during excimer laser corneal ablation.
OBJECTIVE
Although the empirical characteristics of ArF excimer laser corneal ablation have been well documented, the exact ablation mechanisms are not well understood. The present paper reports a quantitative analysis of corneal ablation plumes using in situ time resolved laser light scattering and Raman spectroscopy.


METHODS
Bovine corneas were used as the ArF excimer laser ablation targets. Light scattering data were recorded from the ablation plume as a function of height above the tissue surface and as function of delay time with respect to the ablative ArF laser pulse.


RESULTS
Raman spectra of the ablation plume allow identification of the particles as water. Mean plume particle diameters are found to decrease with height, while the particle volume fractions are relatively constant. The total volume of plume particles correlates well with the total volume of water in the ablated corneal tissue.


CONCLUSIONS
The finding of a non-evolving plume composed of water spherules, combined with the excellent agreement between total volume of water in the plume and the content of water in the ablated corneal tissue, support the concept of photodecomposition or "cold ablation" for corneal tissue during ArF excimer laser ablation.
Hahn
D W
DW
FDA Center for Devices and Radiological Health, Rockville, Maryland 20857, USA.
Ediger
M N
MN
Pettit
G H
GH
D000538:Aluminum Silicates; D000818:Animals; D001128:Argon; D001834:Body Water / Q000737:chemistry; D002417:Cattle; D003315:Cornea / Q000737:chemistry / Q000601:surgery*; D005459:Fluorides; D053685:Laser Therapy; D007834:Lasers; D009354:Neodymium; D012542:Scattering, Radiation; D013059:Spectrum Analysis, Raman; D013997:Time Factors; D014466:Ultraviolet Rays; D014835:Volatilization; D014867:Water / Q000032:analysis; D015019:Yttrium
D000538:Aluminum Silicates; D014867:Water; D009354:Neodymium; D015019:Yttrium; C047730:argon fluoride; D001128:Argon; D005459:Fluorides