Safety and efficacy outcomes of the Xen45 Gel Stent use for refractory glaucoma: a surgery series from surgeon trainees at a tertiary teaching hospital

Background To study the effect of an ab interno gelatin stent (XEN45 Gel Stent, Allergan Inc., Irvine, California, USA) on intraocular pressure (IOP) as placed by glaucoma fellowship trainees in eyes with refractory glaucoma. Methods A prospective noncomparative study at a tertiary training center on 28 unique eyes undergoing ab interno gelatin stent implantation by glaucoma fellowship trainees. Data was collected at baseline and postoperatively at day 1, week 1, and months 1, 3, 5, and 12. Primary outcome was mean IOP change. Secondary outcomes included change in number of glaucoma medication classes and visual acuity. Safety outcomes included needling rates. Surgical success was defined by achieving ≥20% reduction in IOP with the same or fewer classes of antiglaucoma medications from baseline without the need for secondary surgical intervention and/or stent removal. Results At baseline, 28.6% (8/28) of the subjects had prior failed incisional glaucoma surgery in a study population that was 54% African-American, with 78% with severe glaucoma (average mean deviation of − 14.58 dB). Thirteen subjects terminated their clinic visits before their 12-month postoperative visit, leaving 15 subjects for end point analysis. Average IOP went from 21.6 mmHg (range 12.0–31.0, SD 6.6) at baseline to 12.5 mmHg (range 7.0–19.0, SD 3.6), a 42.1% reduction ( p < 0.007). All subjects decreased the number of medication classes they were taking with an average reduction of 3.8 (range 2–5, SD 0.9) to 1.3 (range 0–3, SD 1.0) classes, or a 65.8% decrease ( p < 0.006). Crude surgical success was 80.0% for the 15 subjects that followed up at 12 months. The Kaplan-Meier cumulative probability of success for all 28 subjects at 12 months was 70.4% (95% CI: 44.7–85.8%). Regardless of the length of follow-up, 21.4% (6/28) met failure criteria: 3 subjects failed because they required secondary surgical intervention, and the other 3 did not have adequate IOP reduction. Initial bleb needling rate was 28.6% (8/28) and repeat was 17.9% (5/28). Conclusions Compared to the reported literature with experienced ocular surgeons, ab interno gel stent placements by glaucoma fellowship trainees have similar mean IOP, topical medication reduction, surgical success, and needling rates at 12-month follow-up.