A retrospective study was made of 319 cases operated upon between 1970 and 1975 with evaluation of the postoperative results (average period of observation 34.4 months, never less than 2 years). When compared to fistulisating interventions according to the Scheie procedure, we found the pressure lowering effect to be comparable, however the intra- and postoperative complication-rate and the tendency to develop cataract definitely less. This may be due to a) covering of the fistula by a scleral lamella and b) the use of the operating microscope.