Early Postoperative Intraocular Pressure is Associated With Better Pressure Control After XEN Implantation

PRéCIS:: Gel stent implantation is a bleb-forming surgery designed to achieve predictable pressure drop. An early low intraocular pressure (IOP) is associated with the long-term success of the procedure. PURPOSE: To identify the variables associated with the success of the XEN procedure. PATIENTS AND METHODS: This was part of a prospective, uncontrolled, consecutive case series study. Patients with primary open-angle glaucoma or pseudo-exfoliative glaucoma were included. All the patients underwent surgical XEN implant procedure with mitomycin-C subconjunctival injection 20 minutes before surgery. Success criteria were an off-medication IOP of 6 to 16 mm Hg 12 months after surgery; no additional glaucoma surgery; no visual threatening complications, no visual acuity loss >1 Snellen line. One eye per patient was considered for statistical analysis. A univariate Cox proportional hazard regression analysis was performed to identify potential risk factors for surgical failure. Then, a multivariate Cox model was built. RESULTS: One hundred twenty-three patients were recruited in this study: 93 patients underwent XEN implantation alone whereas 30 the combined procedure with phacoemulsification and intraocular lens implantation. Univariate Cox regression showed that the day after surgery intraocular lens>9 mm Hg was associated with surgical failure (P=0.02) and a postoperative number of needlings ≥2 in the follow-up was also predictive of surgical failure (P<0.01). These data were confirmed by a multivariate model too. At 1 year the surgical success criteria were 76% in the group with 24-hour IOP≤9 mm Hg, whereas it was 43% when above 9 mm Hg (P=0.026). CONCLUSIONS: Our study shows that an early IOP≤9 mm Hg is predictive of the efficacy of the procedure during 1-year follow-up, whereas more than 2 needlings are predictive of failure.