Ectopic Filtering Bleb After Ahmed Glaucoma Valve Implantation Treated With Transconjunctival Mattress Sutures: A Case Report

Giant bleb formation is an uncommon complication following Ahmed glaucoma valve implantation and has most often been described in association with localized encapsulation around the valve plate. We report the case of a 74-year-old man with pseudoexfoliation glaucoma who developed a large cystic inferonasal bleb six weeks after pars plana implantation of an Ahmed glaucoma valve in the inferotemporal quadrant of the right eye. At presentation, the intraocular pressure was 7 mmHg, and slit-lamp examination suggested communication between the base of the bleb and the valve plate. The bleb was drained, and two transconjunctival horizontal mattress sutures were placed at the presumed site of communication. Following surgery, the ectopic bleb regressed completely, and intraocular pressure remained stable throughout follow-up for 10 months. This case suggests that ectopic bleb formation may arise through mechanisms other than encapsulation, likely related to redistribution of aqueous humor along adjacent subconjunctival tissue planes. In such cases, transconjunctival suturing may represent an effective approach to limit bleb expansion while preserving implant function.