Evaluation of Risk Factors for Glaucoma Drainage Device–related Erosions: A Retrospective Case-Control Study

PURPOSE:To identify risk factors for glaucoma drainage device (GDD) erosions. PATIENTS AND METHODS:In a retrospective comparative case series, medical records of 1013 patients who underwent GDD surgery performed by 5 surgeons between 2006 and 2011 were reviewed. The outcome measures assessed included age, race, sex, contact lens wear, seasonal allergies, medical comorbidities, glaucoma diagnosis, preoperative oral and topical medications, type and number of preoperative surgeries and lasers, concomitant surgeries, tube type and position, patch graft material, and intraoperative use of Avastin, mitomycin-C, or Triescence. The association of variables with erosion status was evaluated using the Fisher exact test for categorical variables and the exact Wilcoxon rank-sum test for continuous variables. RESULTS:Charts were included from 339 eyes that had complete data sets and at least 6 months of follow-up. Twenty-eight eyes (8.3%) developed conjunctival erosions. The median follow-up time was 2.03 years for the erosion group and 1.71 years for nonerosion group. Erosion was only associated with the presence of concomitant surgical procedures at the time of GDD implantation (35.7% erosion group vs. 17.4% nonerosion group, P=0.02, OR=2.64). The majority of concomitant surgeries were composed of pars plana vitrectomy (35.0%) and cataract surgery (32.0%). Variables that were suggestive of association with erosion (P