Temporary Filtering Bleb Failure Induced by Anterior Chamber Sulfur Hexafluoride Gas: A Complication after Descemet Membrane Endothelial Keratoplasty

Abstract

Herein, we report two clinical cases with acute temporary filtering bleb obstruction by gas tamponade after Descemet membrane endothelial keratoplasty (DMEK) surgery and postoperative intraocular pressure (IOP) peaks. Both patients underwent uncomplicated DMEK surgery with 20% sulfur hexafluoride (SF₆) anterior chamber tamponade and had previous trabeculectomy for glaucoma. Prior to surgery, both patients showed patent bleb function with low to normal IOP without antiglaucomatous medication. After uneventful DMEK surgery, both patients showed postoperative IOP peaks of up to 50 mm Hg despite patent inferior iridotomy and no sign of a pupillary block. In both cases, SF₆ gas bubbles could be visualized obstructing the bleb. Both patients were treated with IOP-lowering agents topically as well as systemically. In addition, anterior chamber paracenteses were performed to reduce the SF₆ volume within the anterior chamber. Under this treatment, IOP normalized within the first 18 h after surgery. We hypothesize that the SF₆ gas tamponade from the anterior chamber migrates into the ostium and below the bleb, leading to an acute temporary insufficiency of bleb function and to a consecutive IOP peak after surgery. In contrast to a pupillary block, this mechanism cannot be antagonized by preoperative iridotomy and needs to be taken into account for every glaucoma patient with functional bleb undergoing DMEK surgery.

Impact of Early Intraocular Pressure Elevation on Postoperative Outcomes After Descemet Membrane Endothelial Keratoplasty in Non-glaucoma Patients

“…Although previous studies found no evidence that the choice of endotamponade [20% sulfur hexafluoride (20% SF6) or air] has an impact on IOP after DMEK, [12][13][14][15][16] a variety of other patientrelated and surgery-related factors such as previous surgery and preoperatively elevated IOP seem to play a role. [17][18][19] Early detection and immediate treatment are crucial to avoid ocular damage including Urrets-Zavalia syndrome. In general, high IOP like in primary angle-closure glaucoma may cause significant changes in corneal endothelial cell count (ECC), central corneal thickness (CCT), and visual acuity.…”

Graft survival of Descemet membrane endothelial keratoplasty (DMEK) in corneal endothelial decompensation after glaucoma surgery

“…DMEK in glaucomatous eyes with previous glaucoma surgery is frequently challenging due to progressed corneal edema, anatomical alterations of the anterior chamber-like anterior synechiae, tube endings from glaucoma drainage devices (GDD), or large iridectomies after trabeculectomy. This can complicate unfolding of the graft or lead to an accelerated postoperative loss of gas from the anterior chamber resulting in an increased risk of graft detachment [11][12][13]. The rate of graft failure in eyes with preexisting glaucoma and after glaucoma surgery is reported to be increased [14,15].…”