[The relationship between pressure regulation and anatomic localization as well as trephine sites in goniotrepanation. A prospective study].

Long-term regulation of IOP after trephining procedures was studied in 65 eyes with regard to the anatomical localization of the trephine hole. The observation period ranged between six and 39 months. The anatomical localization had no statistically significant influence on long-term pressure regulation after surgery, nor on the immediate postoperative situation. It was clinically impossible to localize the trephine within the trabecular area including Schlemm's canal with a high degree of accuracy. The use of larger-diameter trephines did not increase the probability of striking Schlemm's canal. With larger-diameter trephines the immediate effect on IOP was more pronounced, but the long-term IOP response was poorer. The absence of a filtering bleb or the development of a large filtering bleb was significantly more often associated with poor regulation of IOP in the long term. Where the trephine was positioned closer to the sclera, the incidence of choroidal detachment was higher. The diameter of the trephine had no effect on the occurrence of postoperatively flat chambers or choroidal detachments. Nor did the anatomical localization influence the incidence of postoperatively flat chambers.