Outcomes of Surgical Revision of Glaucoma Drainage Devices for Tube Obstruction

Abstract

Purpose: : Glaucoma drainage devices (GDDs) are frequently used in the management of patients with glaucoma. A known complication of GDD surgery is tube obstruction. The purpose of this study is to determine the frequency of GDD occlusion warranting surgical revision and the outcome of revision surgery for this complication.

Methods: : Using billing records, we retrospectively identified all patients who underwent implantation and subsequent surgical revision of a GDD for tube obstruction at Duke University Medical Center from 2002-2006. We extracted information regarding possible risk factors for GDD occlusion as well as information on postoperative outcomes following GDD revision surgery.

Results: : Of the 1290 GDDs implanted during this period, 35 (2.7%) required at least one surgical revision due to GDD obstruction. 9 out of 488 Baerveldt implants (1.8%) and 20 out of 802 Ahmed implants (2.5%) developed a blocked GDD that required surgical revision (p=0.50). At 1 month following revision, 10 eyes (23%) had improved BCVA by >3 lines while 8 eyes (18%) had a loss in BCVA of >3 lines. 26 eyes (59%) had intraocular pressures between 6 and 21 mm Hg at 1 month after the revision. 36% of the patients had an IOP >21 before the revision and then achieved an IOP between 6-21 while 11% had an IOP between 6-21 before the revision and after the revision the IOP was >21 or <6. 28 eyes (80%) required only 1 surgical revision while the remaining patients required 2-3 revisions before the GDD was functioning properly. 3 of 12 cases that underwent tube flushing along with repositioning (25%) required an additional surgical revision while 11 of 25 cases that underwent flushing without repositioning required an additional surgical revision (44%) (p=0.60).

Conclusions: : With the increasing use of GDDs in the management of glaucoma patients, it is important to be familiar with how to handle these challenging cases and the outcomes of revision surgery for this complication. While some of the patients in this series responded quite well to the revision surgery, others continued to experience vision loss or difficulty with intraocular pressure control necessitating additional interventions.

Keywords: clinical (human) or epidemiologic studies: outcomes/complications • clinical (human) or epidemiologic studies: prevalence/incidence • intraocular pressure