Soft Tissue Effects of the THC:YAG Laser on Canine Vocal Cords

Recently, a laser based on a thulium-holmium-chromium (THC) doped yittrium-aiuminum-garnet (YAG) rod has been developed that produces light of 2.15 microns wave-length and can be transmitted through a low OH- silica fiberoptic cable. This wave-length falls on one of the peaks of the energy absorption spectrum of water. Thus, the THC:YAG laser eliminates the disadvantage of a cumbersome delivery system found in the CO₂ laser while still providing precise cutting and minimal tissue injury inherent in lasers emitting light absorbed by water. We evaluated the soft tissue effects of this laser on canine vocal cords. Ablative lesions were produced by the THC:YAG laser and histologically examined on postoperative days 1, 7, and 28. Results indicate that the depth of tissue penetration is easily controlled and the healing response to tissue injury is comparable to that of the CO₂ laser. The THC:YAG laser should prove to be a superior laser for use in otorhinolaryngology, especially when adapted to a flexible endoscope.