Experimental and clinical results with the Er : YAG laserotoscope

Background and objective. Laserotoscopes are suitable for low-pain outpatie nt surgery of otitis media with effusion (OME) under topical anesthesia. Th e myringotomy perforations should have a diameter greater than 2 mm to vent ilate the middle ear for approximately 3 weeks. Patients/Methods. In this study, the clinical applicability of a prototype of an Er:YAG laserotoscope (Baasel Lasertechnik, Starnberg, Germany) was te sted. Formalin-fixed human tympanic membranes yielded the parameters suitab le for clinical application of an Er:YAG laserotoscope in patients. With a focussed laser beam (beam diameter 500 mum), one is able to achieve perfora tions of 50-mum diameter with one single laser pulse applying pulse energie s of 70 mJ (energy density 36 J/cm(2)). The ablation rate, i.e., the tissue layer that is ablated per laser pulse, is 100 mum using pulse energies of 70 mJ. This means that formalin-fixed human tympanic membrane can be perfor ated with one single laser pulse. Results. Ten patients with OME (otitis media with effusion) were treated un der topical anesthesia of the tympanic membrane (8% tetracainbase in Isopro panol for 15 min) with focussed laser pulses (beam diameter 500 pm) with en ergies of 100 mJ (energy density 52 J/cm(2)). A sufficient perforation diam eter of 2 mm could be achieved with an average of 15 juxtaposed laser appli cations. The enlargement of the perforations was made difficult by extrudin g middle ear secretions and slight bleeding of the tympanic membrane. Betwe en laser applications, the target tissue had to be cleaned by suctioning us ing the operation microscope. The healing of the tympanic membrane was veri fied and compared in postoperative clinical followups. With a perforation d iameter of 2 mm, the Er:YAG laser myringotomies healed within 14 days. The used parameters did not generate side effects such as inner ear hearing los s. Conclusions. An effective, easy, and practical performance of laser myringo tomy is not currently possible with the Er:YAG laserotoscope.