Long-term outcome following trabeculectomy: II Visual field survival.

The long-term changes of the visual field defects of 54 glaucoma patients operated on with trabeculectomy were reviewed. Five years after operation 28% of the patients had suffered from further loss of visual field despite lowering of the intraocular pressure (IOP). All but three of these patients had their postoperative IOP regulated within statistically normal levels (11-21 mmHg). All patients with continued loss of postoperative field were generated from groups of patients with milder to moderate preoperative field defects (stages 0-III classification of Aulhorn, 1979). No patients suffered from sudden field loss after surgery. The mean of the preoperative IOP and the mean of the percent IOP reduction postoperatively were not significantly different in patients with or without continued postoperative visual field loss. This indicates that other factors than normalization of intraocular pressure play an important role in the group of patients with progression of visual field defects following surgery.