Experimental study of CO2 laser myringotomy with a hand-held otoscope and fiberoptic delivery system.

CO2 laser myringotomy has previously been proven effective in patients with serous otitis media for short-term aeration of the middle ear. However, the system based on a microscope and a coaxially aligned laser is cumbersome and expensive. The advantage of CO2 laser energy is the high absorption coefficient in biological tissue, meaning minimal damage surrounding the desired lesion. The disadvantage is that conventional optical fibers do not transmit CO2 laser energy (lambda = 10.6 microns). We have developed a silver halide optical fiber of diameter 0.9 mm and lengths of several meters, with high transmission at 10.6 microns. Using a hand-held otoscope coupled to a fiberoptic delivery system, CO2 laser myringotomies were performed in guinea pigs. In the animal model the feasibility of the procedure was proven. Different irradiation parameters were studied and a "dose-dependent" relationship was found between the total energy used and the duration of a patent myringotomy. However, conventional histological studies failed to show a difference in circumferential damage with different energy parameters. CO2 laser myringotomy utilizing a hand-held otoscope coupled to an optical fiber capable of transmitting CO2 laser energy may prove simple and effective. The relationship between energy parameters and myringotomy patency may be instrumental in deciding on the optimal duration of aeration of the middle ear in secretory otitis media.