Predictors of Surgical Failure in Glaucoma Valve Implantation

Preoperative and postoperative IOP measurements and number of medications were compared using the Wilcoxon signed rank test. Cumulative survival rates were calculated using Kaplan-Meier survival analysis. Cox proportional Hazards regression analysis with forward stepwise elimination was used to assess potential predictors for surgical failure. We included variables previously listed as risk factors according to the litera-ture.^{5 (link)6 (link)} The following variables were studied: Race, eye (right or left), glaucoma diagnosis, gender, preoperative IOP, previous glaucoma surgeries, preoperative glaucoma medications, preoperative use of oral acetazolamide, interval between last surgery and implant, type of implant, quadrant of valve implantation, and occurrence of hypertensive phase in the postoperative period. Data analyses were performed using Statistical Package for the Social Sciences (SPSS) version 19.0 (Inc., Chicago, IL). All reported probability values are two-tailed, and p < 0.05 was considered statistically significant.