Aiming criteria for neodymium-YAG laser trabeculotomy. A clinico-pathological study.

Recently reported clinical and experimental studies have shown that pulsed neodymium-YAG laser trabeculotomy may reduce intraocular pressure but not in all cases. We report a clinico-pathological study designed to delineate the aiming criteria required to produce a fistula between the anterior chamber and the canal of Schlemm. In summary, the aiming beam must be centred on the reflecting surface of the gonioscopic contact lens, and aimed at the posterior trabecular meshwork. This study also indicates that the energy levels required to produce a discrete trabeculotomy in vivo are similar to those determined by in vitro studies.