Eyeworld

AUGUST 2020 | EYEWORLD | 25 of the study to identify significant differenc- es between treatment groups, especially with events that have a low rate of occurrence like surgical complications. The study protocol did not include a washout measurement of IOP preoperatively and at 1 year, which would have been helpful in determining the efficacy of each treatment. There was also no algorithm for postoperative drop escalation. Instead, these de- cisions were left to the investigator's discretion, which is potentially problematic as they were not blinded to the patient's treatment group. Open angle glaucoma is a slowly progres- sive disease that can take decades to evolve. 8 Thus the longevity/durability of surgical interventions is important when determining the success of a procedure. While 12 months is a commonly used endpoint as seen in this study, differences in performance and safety may not manifest until several years after surgery as demonstrated by another MIGS procedure, the now defunct CyPass Micro-Stent (Alcon). 9 It would have been interesting to follow the treatment groups experienced an IOP increase of 10 mm Hg or more postoperatively. Discussion Several studies have compared the KDB and iStent combined with cataract surgery in a retrospective fashion, but this is the first study to do so in a prospective randomized man- ner. 4–6 As in the prior studies, the authors found that KDB-phaco outperformed iStent-phaco. Specifically, KDB-phaco was superior when looking at the primary outcome, which was the proportion of eyes with an IOP reduction ≥20% or reduction of IOP-lowering medica- tions by ≥1 compared to baseline. Selecting this as the primary outcome reflects the general goal of MIGS procedures as stated by the authors, which is to alleviate "patient-specific" issues related to glaucoma medication burden and to achieve modest IOP reductions. 7 While it is exciting to see another prospec- tive randomized controlled trial added to the MIGS literature, there are several limitations to the study. As the authors point out, the sample size was relatively small. This limits the power trabecular micro-bypass stent implantation: mild to moderate open-angle glaucoma" References 1. Budenz DL, Gedde SJ. New options for combined cataract and glaucoma surgery. Curr Opin Ophthalmol. 2014;25:141–147. 2. Lavia C, et al. Minimally-invasive glaucoma surgeries (MIGS) for open angle glaucoma: A systematic review and meta-analysis. PLoS One. 2017;12:e0183142. 3. Richter GM, Coleman AL. Mini- mally invasive glaucoma surgery: Current status and future prospects. Clin Ophthalmol. 2016;10:189–206. 4. Le C, et al. Surgical outcomes of phacoemulsification followed by iStent implantation versus goniot- omy with the Kahook Dual Blade in patients with mild primary open-an- gle glaucoma with a minimum of 12-month follow-up. J Glaucoma. 2019;28:411–414. 5. Dorairaj SK, et al. A multi- center retrospective comparison of goniotomy versus trabecular bypass device implantation in glaucoma patients undergoing cataract extraction. Clin Ophthalmol. 2018;12:791–797. 6. ElMallah MK, et al. 12-month retrospective comparison of Kahook Dual Blade excisional goniotomy with iStent trabecular bypass device implantation in glaucomatous eyes at the time of cataract surgery. Adv Ther. 2019;36:2515–2527. 7. Davis SA, et al. Drop instillation and glaucoma. Curr Opin Ophthal- mol. 2018;29:171–177. 8. Heijl A, et al. Natural history of open-angle glaucoma. Ophthalmol- ogy. 2009;116:2271–2276. 9. Lass JH, et al. Corneal endothelial cell loss and morphometric changes 5 years after phacoemulsification with or without CyPass Micro-Stent. Am J Ophthalmol. 2019;208:211– 218. 10. Slabaugh MA, et al. The effect of phacoemulsification on intraocular pressure in medically controlled open-angle glaucoma patients. Am J Ophthalmol. 2014;157:26–31. Bascom Palmer Eye Institute residents Source: Bascom Palmer Eye Institute continued on page 26

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