PHOTOTHERMAL-INDUCED TEMPERATURE-CHANGES IN A MODEL INNER-EAR - A COMPARISON OF VISIBLE, INFRARED, AND ULTRAVIOLET-LASERS

In this paper, the temperature change in a model cylindrical vestibule (90 mm(3)) was measured following irradiation by argon (488-514 nm), CO2 (10.6 mu m), KTP(Nd:YAG) (532 mm), Er:YAG(2.9 mu m), and XeCl (308 nm) lasers, Otic capsule bone was used to simulate the otosclerotic s tapes footplate, and the thickness of each specimen was machined to va riable thicknesses (0.20-0.90 mm), Thermocouples were used to measure the temperature below the air-bone surface at depths of 1.0, 3.0, and 5.0 mm, The time-dependent temperature change, thermocouple position, and bone thickness were measured following single pulse application fr om argon, CO2, and KTP(Nd-YAG) lasers. The effect of infrared and ultr aviolet lasers on vestibule fluid temperature changes were studied wit h several fluence and pulse sequences, The temperature change in the v estibule following pulsed laser irradiation decreased with increasing bone thickness and thermocouple depth, Laser irradiation from CO2, arg on, KTP-532, XeCl, and Er:YAG lasers produced minimal (less than 5 deg rees) vestibule temperature changes, Measured temperatures were in goo d agreement with an analytic model, based on a solution to the bio-hea t equation in semi-infinite media, The results are discussed with rele vance to ear surgery.