Temperature increase measurements of multiple 10 ms pulses of 2.01 μm laser light incident on ex-vivo rabbit corneas
Date
2011
Authors
Kelly, Edward, author
Johnson, Thomas, advisor
Brandl, Alexander, committee member
Woody, Robert, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Current laser safety standards for multiple-pulse lasers are based primarily on modeling and the results of single-pulse studies. Previous thermal effects studies have focused on histological and visible endpoints, with only a few studies examining the actual temperatures achieved. The goal of this research was to probe the actual temperature profile produced by 2.01-micron laser pulses in the cornea. In this study the corneal temperature rise from multiple 2.01-micron Tm:YAG laser pulses was investigated using ex-vivo rabbit eyes. An infrared thermal camera employing microbolometer detectors captured surface temperature rises resulting from laser pulses. Thermal measurements were taken with single 10-ms pulses as well as two-, three-, and four-pulse sequences while holding the total energy delivered constant for the two- through four-pulse train measurements. An average temperature increase of 8.3 degrees C was observed with the single pulse at 2.8 J/cm2/pulse irradiance. For two pulses, an average temperature increase of 10.0 degrees C was observed for 2.7 J/cm2/pulse irradiance. For three pulses, an average temperature increase of 5.8 degrees C was observed for 1.9 J/cm2/pulse irradiance. For four pulses, an average temperature increase of 4.4 degrees C was observed for 1.5 J/cm2/pulse irradiance. A comparison of the data to temperatures required for denaturing proteins and the current laser safety guidelines is presented. It appears that the MPE may be overly conservative by a factor of at least 15. It is recommended that the 2.01-micron laser MPE be investigated to determine if a revision of the standard is warranted.
Description
Rights Access
Subject
2.01 micron laser pulses in the cornea
laser safety standards for multiple pulse lasers
laser safety guidelines
corneal temperature rise