Outcomes of the Shunt Tube Exposure Prevention Study (STEPS), A Randomized Clinical Trial

Abstract Purpose To compare the long-term safety and efficacy of amniotic membrane-umbilical cord (AM-UC) and pericardium patch grafts in reducing glaucoma shunt tube exposure. Design Multicenter, prospective, randomized clinical trial. Subjects Adults with uncontrolled glaucoma undergoing glaucoma drainage device (GDD) implantation. Methods Subjects were randomized to receive GDD with either AM-UC (Amnioguard™, BioTissue, Miami, FL) or pericardium (Tutoplast®, IOP, Costa Mesa, CA) to cover GDD tubes. Subjects were followed clinically with anterior segment optical coherence tomography (AS-OCT) to prospectively assess patch graft stability and host-tissue integration. Main Outcome Measures Tube exposure, graft thinning and graft-related complications. Results A total of 81 eyes of 81 patients (50 females, 31 males) aged 67±13 years underwent GGD implantation using Baerveldt (n=72) or Ahmed valve (n=9). Tubes were inserted in the anterior chamber (n=71), Sulcus (n=6) or pars plana (n=4). Tube ligation was performed with Baerveldt GDD along with fenestration (n=51) or orphan trabeculectomy (n=21). Tubes were covered with AM-UC (n=41) or pericardium (n=40). The mean follow-up time was 29±8 months (range, 13-40 months). Tube exposure occurred in 1 eye (2%) in the AM-UC group at 3 months and 2 eyes (5%) in the pericardium group at 2 and 6 months (p=0.54). Sequential AS-OCT showed better host-tissue integration and significantly less graft thinning in the AM-UC group. Early graft thinning (≤ 3 months) occurred in 5 eyes (12%) in the AM-UC group and 17 eyes (43%) in the pericardium group (p=0.002). Late thinning occurred in 2 eyes (5%) and 11 eyes (28%) in the AM-UC and pericardium group, respectively (p=0.007). Graft translucency and cosmetic appearance of AM-UC were superior to pericardium. No evidence of graft rejection or infection was associated with the patch grafts in either group. Conclusion AM-UC grafts are well-tolerated and offer an alternative to pericardium for safe and stable tube shunt coverage. Its high tensile strength, low immunogenicity, and excellent host-tissue integration significantly reduced graft thinning. AS-OCT is a useful tool in evaluating patch grafts following GDD surgery.