Abstract
Abstract: :
Purpose: There are different strategies to lower the intraocular pressure (IOP) by laser surgery. Excimer Laser Canalostomy (ELC) can be used to ablate the inner wall of Schlemm`s canal in order to reduce the outflow resistance generated by the anterior juxta-canalicular trabecular meshwork. Methods: ELC is performed by creating a scleral flap and opening Schlemm`s canal. The ELC probe (maximum diameter 280 µm) was introduced into the canal. The radius of the probe was designed to follow the curvature of Schlemm`s canal, either right or left of the incision . An excimer laser with a wavelength of 308nm (AIDA, TuiLaser AG, Munich) was used for intracanalicular photo ablation. The pulse length was 80ns, repetition rate was 20 Hz and energy was 160 µJ at the tip coupled out by a gold mirror at an angle of 40°. The laser was programmed on 20 pulses per ablation spot. Generally between 4-5 ablation spots were applied on each side. We evaluated the effect of ELC ablation of the inner wall of Schlemm`s canal in cadaver eyes and demonstrated the feasibility of the method in patients. Results: The side firing tip was inserted into Schlemm`s canal without mechanical perforation into the anterior chamber visible by light microscopy. Histological examination of human donor eyes confirmed the atraumatic nature of the procedure and demonstrated a thermal damage of less than 2 micron. Intraoperative handling of the tip was uneventful in initial patiens as judged by contact mirror lens. No bleeding or oedema was observed. Conclusions: ELC is a new technique that widens the spectrum of non-penetrating glaucoma surgery. The results indicate that ELC is a safe procedure that avoids early postoperative complications of filtering surgery. Since the target tissue is the inner wall of Schlemm`s canal, scar formation may be less pronounced. The IOP lowering properties will be determined when one year following data of our patients become available.
Keywords: laser • outflow: trabecular meshwork • trabecular meshwork