Comparison of Outcomes of Glaucoma Drainage Implant Surgery With or Without Prior Failed Trabeculectomy

Precis: A comparison of 186 glaucoma patients with mixed diagnoses who underwent nonvalved glaucoma drainage device (GDD) implant surgery showed similar long-term intraocular pressure (IOP), medication, and visual acuity (VA) outcomes between those with prior failed trabeculectomy surgery versus those without. Purpose: The purpose of this study was to evaluate whether prior failed trabeculectomy adversely affects the outcome of glaucoma tube surgery. Patients and Methods: A total of 186 eyes of 186 patients who underwent a nonvalved GDD implant surgery by a single surgeon between 1996 and 2015 at a University practice were included. Patients were of mixed diagnoses and over 18 years old. Before the GDD surgery, 65 had a previous failed glaucoma filtering surgery and 121 had no prior glaucoma surgery. Demographic information, preoperative and postoperative IOP, medication, VA, and complications were collected from chart review. Results: No significant difference was noted in mean IOP and mean medication use (13.0 and 12.6 mm Hg on 2.0 and 1.7 medication classes at 5 y postoperatively, respectively), mean VA and change in VA from baseline, or numbers of complications (P>0.05), between eyes that had a prior failed filtration surgery and those that had not. Kaplan-Meier plots for failure over 5 years using a lower limit of <5 mm Hg and an upper limit of >= 18, >= 15, or >= 12 mm Hg did not show a significant difference between groups. Subanalyses were performed to examine only primary glaucoma eyes and results were similar. Further group subanalyses comparing those with baseline IOP >= 25 or <25 mm Hg, age 65 and above or below 65 years and those specifically with Baerveldt 350 mm(2) implants also did not show significant differences. Conclusion: Prior failed filtration surgery does not appear to affect the outcome of future GDD surgery.