EyeWorld India March 2018 Issue

53 EWAP DEVICES March 2018 present in the study: those who re- ceived concurrent cataract surgery with iStent insertion and those who received iStent insertion only. As was discussed by the authors, cataract surgery is known to have an IOP-lowering effect. Notably, elevated preoperative IOP, as these patients had, is correlated with a large postoperative IOP decrease. 11 These patients essentially under- went two interventions that could have provided IOP reduction and hence deserve a separate sub- group analysis. Perhaps a cataract extraction-only group could have been identified and utilized as a control group, although their preoperative IOP would likely have been lower than the study group. It also would have been useful to compare this novel approach in advanced glaucoma with the cur- rent standard of care for refractory glaucoma (i.e., repeat trabeculecto- my or tube shunt surgery). A table summarizing the baseline demo- graphic and ocular characteristics of the study population would have been helpful. Elapsed time between the last prior filtration surgery and the current interven- tion would be information of interest to readers. We were surprised to see no statistical analyses when reviewing the results. Student’s t-test analy- ses would be essential in demon- strating statistical significance regarding the decrease in IOP and number of medications. No intra- operative or postoperative com- plications were seen in the study. However, it would have been use- ful to know what specific compli- cations were tracked. A significant percentage (36%) of patients re- quired additional surgery after the intervention, yet no additional in- formation regarding this subset of patients was provided. What was the mean time to failure in this group? A Kaplan-Meier survival curve would be useful here. Were these patients included in the final analysis? Perusal of Figures 2 and 3 in the journal article shows only 25 data points cumulatively, yet the sample size consists of 42 eyes. It is unclear from the text why a portion of the study eyes was not included in this graph. We applaud the authors for a novel hypothesis regarding the utility of angle surgery in ad- vanced glaucoma patients who have failed filtration surgery and for conducting this initial assess- ment. This possibility is one that deserves further consideration after the study’s findings, given the limited options that currently exist in the management of refrac- tory, severe glaucoma. EWAP References 1. Saheb H, et al. Micro-invasive glau- coma surgery: current perspectives and future directions. Curr Opin Ophthalmol. 2012;23:96– 104. 2. Richter GM, et al. Minimally inva- sive glaucoma surgery: current status and future prospects. Clin Ophthalmol. 2016;10:189–206. 3. Gedde SJ, et al. Postopera tive compli- cations in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up. Am J Ophthalmol. 2012;153:804–814. 4. Gedde SJ, et al. The Tube Versus Trab- eculectomy Study: Interpretation of results and application to clinical practice. Curr Opin Ophthalmol. 2012;23:118–26. 5. Lavia C, et al. Minimally-invasive glaucoma surgeries (MIGS) for open angle glaucoma: A systematic review and meta- analysis. PloS One. 2017;12:e0183142. 6. Resende AF, et al. IStent trabecular mi- crobypass stent: An update. J Ophthalmol. 2016;2016:2731856. 7. Samuelson TW, et al. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmol. 2011;118:459– 67. 8. Katz LJ, et al. Prospective randomized study of one, two, or three trabecular bypass stents in open-angle glaucoma subjects on topical hypotensive medication. Clin Ophthalmol. 2015;9:2313–20. 9. Chang DF, et al. Efficacy of two trabecu- lar micro-bypass stents combined with topical travoprost in open-angle glaucoma not controlled on two preoperative medica- tions: 3-year follow-up. Clin Ophthalmol. 2017;11:523–528. 10. Heuer DK, et al. Consensus on definitions of success. In: Shaarawy TM, Sherwood MB, Grehn F, eds. Guidelines on Design and Reporting of Glaucoma Surgical Trials. Amsterdam, the Netherlands: Kugler. 2008:15–24. 11. Slabaugh MA, et al. The effect of phacoemulsification on intraocular pres- sure in medically controlled open-angle glaucoma patients. Am J Ophthalmol. 2014;157:26–31. Contact information Gedde: sgedde@med.miami.edu Trabecular micro-bypass stents as minimally invasive approach after conventional glaucoma filtration surgery – a retrospective analysis since 2014 Thomas Macher, MD, Heike Häberle, MD, Juliane Wächter MD, Carsten Thannhäuser, MD, Henning Aurich, MD, Duy-Thoai Pham, MD J Cataract Refract Surg. 2018;44(1). Article in press. Purpose: To evaluate long-term efficacy and safety of two trabecular micro-bypass stents in patients with advanced primary open angle glau- coma (POAG) and insufficient intraocular pressure (IOP) after previous filtration surgery. Setting: Vivantes Klinikum Neukölln, Augenklinik, Berlin, Germany Design: Retrospective, single-center, open-label, non-randomized study Methods: 42 eyes with uncontrolled and advanced POAG since 2014 were analyzed. All eyes had previously undergone at least one filtration surgery procedure. The anatomical landmarks and configuration of the anterior chamber angle had to be identified easily. Two iStents were placed nasal into Schlemm’s canal. Results: 18 of 42 eyes had one previous glaucoma filtration surgery before. During the follow-up of 12 months mean IOP in cases of primary failure of filtration surgery decreased from preoperative 23.8 (±3.9) mmHg to 15.2 (±2.7) mmHg. For cases with more than one previous filtration surgery mean IOP decreased from preoperative 26.1 (±5.7) mmHg to 16.3 (±3.3) mmHg. Medications were reduced from 2.7 (±0.9) to 2.0 (±1.1). No intraoperative or perioperative complications occurred. Conclusions: For eyes with previous filtration surgery and medically un- controlled IOP the implantation of two iStent inject provided a minimally invasive and safe reduction of mean IOP to <18 mmHg at 12 months. Number of medications could be reduced to improve adherence.