Standalone Ab Interno Gelatin Stent versus Trabeculectomy: Postoperative Interventions, Visual Outcomes, and Visits

Abstract

To evaluate postoperative interventions, visual outcomes, and number of postoperative office visits after standalone ab interno gelatin microstent implantation with mitomycin C (MMC) vs. trabeculectomy with MMC. International, multicenter, retrospective cohort study. A total of 354 eyes of 293 patients, including 185 microstent eyes and 169 trabeculectomy eyes. Consecutive eyes with uncontrolled glaucoma underwent microstent or trabeculectomy surgery from January 1, 2011, through July 31, 2015, at 4 academic ophthalmology centers: Toronto, Canada; Frankfurt, Germany; Salzburg, Austria; and Leuven, Belgium. Assessed outcomes included (1) in-clinic interventions, (2) transconjunctival needle revision (TCNR), (3) postoperative visits at 1 and 3 months, (4) >2 lines vision loss at last follow-up, (5) complete visual recovery, and (6) >0.5 or >1 diopter (D) of surgically induced astigmatism. Ninety-five (51.4%) of the microstent eyes and 105 (62.1%) of the trabeculectomy eyes underwent an intervention by last follow-up (log-rank P= 0.0004). The most common intervention was TCNR, followed by laser suture lysis. Seventy-eight (42.2%) microstent eyes and 55 (32.5%) trabeculectomy eyes received TCNR (adjusted hazard ratio [HR], 1.73 [95% confidence interval (CI), 1.10-2.71]): 128 total TCNRs in the microstent group and 95 in the trabeculectomy group. Predictors for TCNR included prior laser peripheral iridotomy and diabetes. Microstent eyes had on average 1.00 (standard deviation 2.32) fewer visits compared with trabeculectomy eyes in the first month (P < 0.001), adjusted for baseline characteristics. The percentage of eyes that had lost >2 lines of vision at last follow-up or reoperation was 12.4% (95% CI, 8.0%-18.7%) and was 21.9% (95% CI, 15.3%-30.1%) adjusted (P= 0.0383). A higher proportion of microstent eyes regained their baseline preoperative visual acuity compared with trabeculectomy eyes (log-rank P= 0.0250; adjusted HR, 1.46 [95% CI, 1.10-2.00]). Altogether, 25.3% (95% CI, 15.3%-38.9%) of microstent eyes and 40.7% (95% CI, 27.7%-55.3%) of trabeculectomy eyes had > 0.5 D surgically induced astigmatism on an adjusted basis; 8.0% (95% CI, 3.2%-18.6%) vs. 17.3% (95% CI, 8.9%-9.8%) had >1 D. Microstent eyes had more TCNRs (though fewer in-clinic interventions), fewer postoperative visits, and less vision loss, and experienced less surgically induced astigmatism, than trabeculectomy eyes. Overall, the postoperative course was less intensive for the microstent, except for more TCNRs.