IR Lasers and Application Systems for Myringotomy

Abstract

The study examines an Er:YAG laser (2940 nm) and di#erent application systems of the CO 2 laser (10 600 nm) with regard to their suitability for a one-shot laser myringotomy of an adequate perforation size (2 mm). The laser-tissue interaction of the Er:YAG laser and the CO 2 laser in fresh tympanic membranes of horses (thickness: 80-100 m) as well as in formalin-fixed human tympanic membranes (thickness: 100 m) is studied correlating perforation diameters to the applied power/energy density and the e#ects demonstrated by light and scanning electron microscopy are analysed. Using the Er:YAG laser with a focused laser beam (spot diameter: 400 m) or with a maximally defocused laser beam (spot diameter: 1600 m) perforations of an adequte size (2 mm) can only be achieved with multiple laser pulses. Histological studies disclose only minimal thermic side e#ects in the adjacent tissue in both specimens. If the CO 2 laser radiation is transmitted via a silver halide polycrystalline fibre (diameter: 900 m) a maximal perforation diameter of 1300 m is achieved with significant thermic side e#ects such as coagulation. Using an Acuspot 710 micromanipulator (focused beam diameter: 180 m) combined with a SilkTouch scanner a maximal perforation diameters of 1700 m can be achieved in horse tympanic membrane with one laser pulse. A prototype of a hand-held CO 2 laser otoscope in combination with the SilkTouch scanner is suitable for performing laser myringotomies with a diameter of 2 mm with a single laser pulse in fresh horse tympanic membrane.