Surgical landmarks in trabecular surgery.

Clinical and histologic studies in 40 eyes of 35 patients with chronic open-angle glaucoma or chronic angle-closure glaucoma operated by various types of "trabeculectomies" were assessed to evaluate whether success was correlated with the surgical approach or with the presence of trabecular tissue in the pathologic specimen. It was clearly demonstrated that it is not necessary to localize or enter Schlemm's canal in order to perform successful trabeculectomies; it is not necessary to operate posterior to the scleral spur; and it is not necessary to excise either Schlemm's canal or trabecular tissue to achieve success. In essence, trabeculectomies primarily function as fistulizing operations carried out under scleral flaps substituting a scleral-conjunctival barrier to aqueous flow rather than the conjunctival barrier alone provided by standard glaucoma operations. This greater obstruction explains the absence of shallow chambers, the reduced incidence of polycystic bleb formation and, perhaps, an avoidance of long-term complications that often result from these two factors.