Endoscopically controlled erbium YAG laser goniotomy. Initial preclinical trials

Abstract

Endoscopic erbium-YAG laser treatment is a new approach in glaucoma surgery. In contrast to conventional laser systems, the photoablative erbium-YAG laser allows microperforations of the trabecular meshwork without thermal side effects. We report our first preclinical trials using this new system. We used the Endognost system (Schwind Co.). The device combines an endoscope and illumination fiber (0.5 mm diameter), laser fiber (0.5 mm) and a irrigation tube in one probe with a 1.1 mm external diameter. The Endognost system was tested in porcine and enucleated human eyes. All eyes were examined histologically. The endoscopic view into the anterior chamber allows for precise allocation of the laser pulses. Using a single pulse mode with 10 mJ a micropuncture of the trabecular meshwork can be achieved without damaging the adjacent tissue. Using multiple pulses or higher energy levels leads to damage of the posterior wall of Schlemm's canal and to thermal side effects. Endoscope guided erbium-YAG laser effects on trabecular tissue are comparable to those produced by a 308 nm excimer laser. Therefore, a similar reduction in intraocular pressure can be expected.