Research Papers

Theory concerning the ablation of corneal tissue with large-area, 193-nm excimer laser beams

[+] Author Affiliations
Charles R. Munnerlyn, Mark E. Arnoldussen, Audrey L. Munnerlyn, Benjamin A. Logan

Advanced Medical Optics, Incorporated, 3400 Central Expressway, Santa Clara, California 95050

J. Biomed. Opt. 11(6), 064032 (December 13, 2006). doi:10.1117/1.2399091
History: Received July 20, 2005; Revised May 19, 2006; Accepted August 22, 2006; Published December 13, 2006; Online December 13, 2006
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Excimer laser beams (193nm) of uniform fluence were studied to find out why they produce corneal ablations deeper at the edge than the center. Ablation depth profiles were taken of porcine corneas, including five dehydrated samples. Hydrated corneas and polymethyl methacrylate were ablated with and without central masks. Ablation plumes were photographed. Hydrated porcine corneas showed patterns of central underablation. As the incident beam increased, the crater exhibited increasingly shallower central ablation while maintaining nearly constant depth at the edges. Dehydrated corneas did not vary significantly. Masks did not alter the depth or shape of craters near ablation edges, but depth adjacent to the images of the masks was more than twice that with no mask. Depth adjacent to the mask image was nearly the same as at the edge of the zone. The rate of change in depth with position was nearly equal in both areas. Maximum plume density was centered over the entire ablation with and without the mask. Redeposition of plume particles is not the major cause of central underablation. Propagating transverse energy from the absorption of photons by peptide bonds increases pressure on excited components within the irradiated area, increasing recombination, which raises the ablation threshold.

Figures in this Article
© 2006 Society of Photo-Optical Instrumentation Engineers

Citation

Charles R. Munnerlyn ; Mark E. Arnoldussen ; Audrey L. Munnerlyn and Benjamin A. Logan
"Theory concerning the ablation of corneal tissue with large-area, 193-nm excimer laser beams", J. Biomed. Opt. 11(6), 064032 (December 13, 2006). ; http://dx.doi.org/10.1117/1.2399091


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