Morphological studies about the efficiency of laser beams upon the structures of the angle of the anterior chamber. Facts and concepts related to the treatment of the chronic simple glaucoma.

Working at a power density above optical breakdown threshold, irradiation effects upon the angle of the anterior chamber of the Macaca speciosa monkey by a Nd glass Q-switched laser, have been analysed with scanning electron microscopy. Two different damage effects can be identified: openings of Schlemm's canal and the creation of a cyclodialysis, that is opening the uveoscleral outflow routes; the latter may be a more effective one than the former. Also a third mechanism, namely a structural alteration of the trabecular meshwork, at the molecular level by laser action, has been inferred. The physical effects leading to optically induced mechanical damage are discussed. Applicability of such effects upon the morphological findings described here, is limited and to a greater part speculative. A better definition of the physical parameters, required for optimal therapeutical damage effects in the treatment of the wide angle glaucoma may be obtained by trial and error methods, which are guided by the results of electron microscopical analyses of samples obtained from in vivo and in vitro experiments.