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J Biomed Opt. 2015 Oct;20(10):105004. doi: 10.1117/1.JBO.20.10.105004.

Efficacy and predictability of soft tissue ablation using a prototype Raman-shifted alexandrite laser.

Author information

1
Vanderbilt University, Department of Physics and Astronomy, 6301 Stevenson Center, Nashville, Tennessee 37235, United States.
2
Vanderbilt University Medical Center, Department of Ophthalmology and Vanderbilt Eye Institute, 2311 Pierce Avenue, Nashville, Tennessee 37232, United States.

Abstract

Previous research showed that mid-infrared free-electron lasers could reproducibly ablate soft tissue with little collateral damage. The potential for surgical applications motivated searches for alternative tabletop lasers providing thermally confined pulses in the 6- to-7-µm wavelength range with sufficient pulse energy, stability, and reliability. Here, we evaluate a prototype Raman-shifted alexandrite laser. We measure ablation thresholds, etch rates, and collateral damage in gelatin and cornea as a function of laser wavelength (6.09, 6.27, or 6.43 µm), pulse energy (up to 3 mJ/pulse), and spot diameter (100 to 600 µm). We find modest wavelength dependence for ablation thresholds and collateral damage, with the lowest thresholds and least damage for 6.09 µm. We find a strong spot-size dependence for all metrics. When the beam is tightly focused (~100-µm diameter), ablation requires more energy, is highly variable and less efficient, and can yield large zones of mechanical damage (for pulse energies>1 mJ). When the beam is softly focused (~300-µm diameter), ablation proceeded at surgically relevant etch rates, with reasonable reproducibility (5% to 12% within a single sample), and little collateral damage. With improvements in pulse-energy stability, this prototype laser may have significant potential for soft-tissue surgical applications.

PMID:
26456553
PMCID:
PMC4963468
DOI:
10.1117/1.JBO.20.10.105004
[Indexed for MEDLINE]
Free PMC Article

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