Comparing Outcomes of 45 Xen Implantation Ab Interno With Closed Conjunctiva to Ab Externo With Open Conjunctiva Approaches

Abstract

Précis: Ab externo with open conjunctiva placement may lead to improved gelatin stent (XEN® Gel Stent; Allergan™) success rate compared to ab interno with closed conjunctiva because it conferred more favorable results for intraocular pressure and medication burden reduction based on our complete and qualified success criteria. Purpose: To compare outcomes of a gelatin stent (XEN® 45 Gel Stent; XGS; Allergan™) placed either ab interno with closed conjunctiva (AIC) or ab externo with open conjunctiva (AEO) with or without cataract surgery in patients with glaucoma. Design: Retrospective, nonrandomized comparative study of 85 eyes from 85 glaucoma patients who received XGS placed either AIC (N=32) or AEO (N=53) with or without cataract surgery between July 2018 and January 2022 at Massachusetts Eye and Ear. Patients were included if they were≥18 years of age and had at least 30 days of follow-up without any disqualifying event. Results: Baseline demographics were similar between both groups, except for the glaucoma type. Both AIC and AEO procedures resulted in significant patterns of IOP and medication reduction from baseline up to 1 year. At POY1, mean IOP was reduced to 11.34±4 mmHg on 1.29±1.34 medications after AEO, and 13.70±3.32 mmHg on 2±1.81 medications after AIC. The average IOP reduction was significantly greater in the AEO group at all postoperative timepoints beyond POW2. There were significant differences in the survival curves of AEO and AIC groups under both the complete success criteria and the qualified success criteria. Under the complete success criteria, the cumulative probability of survival at POY1 was 28.5% in the AEO group and 3.8% in the AIC group. Under the qualified success criteria, the cumulative probability of survival at POY1 was 60.3% in the AEO group and 21.9% in the AIC group. Conclusion: In our study, we demonstrate that both placements reduce IOP and medication from baseline, with AEO placement having more favorable IOP and medication results, in addition to improved success rates compared to AIC placement.