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

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 MMC subconjunctival injection 20 minutes before surgery. Success criteria were an off-medication IOP of 6 to 16▒mmHg 12 months after surgery; no additional glaucoma surgery; no visual threatening complications, no visual acuity loss greater than 1 Snellen line. One eye per patient was considered for statistical analysis. A univariate Cox's proportional hazard regression analysis was performed to identify potential risk factors for surgical failure. Then, a multivariate cox model was built. Results: 123 patients were recruited in this study: 93 patients underwent Xen implantation alone whereas 30 the combined procedure with phacoemulsification and IOL implantation. Univariate cox regression showed that the day after surgery IOP greater than 9▒mmHg was associated with surgical failure (P=0.02) and a postoperative number of needlings greater or equal to 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 below or equal to 9▒mmHg, while it was 43% when above 9▒mmHg (P=0.026). Conclusion: Our study shows that an early IOP below or equal to 9▒mmHg is predictive of the efficacy of the procedure during 1-year follow-up, while more than two needlings are predictive of failure.