Purpose: The last decade has witnessed an unprecedented growth in glaucoma treatment options through the introduction of minimally invasive glaucoma surgeries (MIGS). The aim of the present review is to provide an understanding of the currently available MIGS and to examine what data are currently available to guide treatment choice. Design: Meta-analysis and systematic review of randomized and non-randomized control trials. Methods: Out of 2567 articles identified, a total of 77 articles were retained for analysis, including 28 comparative studies and 12 randomized control trials. Overall, 7570 eyes were included. When data permitted, the weighted mean difference in intraocular pressure reduction was calculated for comparison purposes. Results: Weighted mean intraocular pressure reductions from all analyzed studies were: 15.3% (iStent), 29.1% (iStent inject), 36.2% (ab interno canaloplasty), 34.4% (Hydrus), 36.5% (gonioscopically-assisted transluminal trabeculotomy), 24.0% (trabectome), 25.1% (Kahook dual blade), 30.2% (Cypass), 38.8% (XEN), and 50.0% (Preserflo). Conclusions: One of the advantages of the heterogenous range of available MIGS options is the chance to tailor therapy in an individualized manner. However, high-quality data are required to make this choice more than an educated guess. Overall, this review confirms the efficiency of assessed MIGS compared with standalone phacoemulsification, but it highlights that only few studies compare different MIGS techniques and even fewer assess MIGS against criterion standard treatments. Current evidence, while non-negligible, is mostly limited to heterogenous nonrandomized studies and uncontrolled retrospective comparisons, with few quality randomized control trials. We suggest that future research should be comparative and include relevant comparators, standardized to report key outcome features, long-term to assess sustainability and late complications, and ideally randomized.

Précis: This study confirms the safety and efficacy of XEN gel stents in the management of pseudoexfoliative glaucoma 2 years after implantation, with success rates similar to primary open-angle glaucoma regardless of the definition of success. Purpose: To compare the long-term safety and efficacy of XEN gel implant surgery (Allergan Inc., Irvine, CA) in patients with pseudoexfoliative glaucoma (PEXG) and primary open-angle glaucoma (POAG). Setting: Prospective, interventional study in a tertiary glaucoma center. Methods: A total of 110 eyes of 85 patients with POAG (57 eyes) or PEXG (53 eyes) and uncontrolled intraocular pressure (IOP) despite medical treatment underwent combined XEN+cataract surgery or standalone XEN surgery. Mean IOP, mean number of medications, needling rates, and incidence of adverse effects were compared between the 2 groups. Complete surgical success was defined as an unmedicated IOP≤12, 15, 16, or 18 mm Hg at 2 years, both with and without a 20% reduction from baseline. Results: Combined XEN+cataract surgery was performed in 72% of POAG and 76% of PEXG eyes (P=0.67), the remainder underwent standalone XEN surgery. Patient characteristics were similar between the 2 groups except for older age for the patients with PEXG (78.5±8.5 vs. 71.3±8.7 y; P<0.005). Mean medicated IOP were 19.8±5.8 mm Hg (POAG) versus 19.8±8.2 mm Hg (PEXG) at baseline (P=0.98), and 14.5±3.6 mm Hg (−26.8%) versus 14.2±3.8 mm Hg (−28.3%), respectively, at 2 years (P=0.75). Mean medications concomitantly dropped from 1.9±1.6 (POAG) versus 2.0±1.3 (PEXG) to 0.6±0.9 versus 0.4±0.7, respectively (P=0.29). Using the 16 mm Hg threshold, 51.4% (POAG) versus 57.1% (PEXG) eyes achieved complete success (P=0.70) at 2 years. The difference in success rates between the 2 groups was not statistically significant under any of the definitions of success. By 24 months, needling was performed in 42.8% (POAG) and 43.2% (PEXG) (P=0.64), with an average time to needling of 162.8 and 134.9 days, respectively (P=0.46). The rates of adverse effects were 30.6% (POAG) and 36.4% (PEXG) (P=0.66), and additional glaucoma surgeries were carried out in 14.3% (POAG) versus 15.9% (PEXG) (P=0.89). Conclusions: The XEN gel implant as a standalone or combined procedure demonstrated similar efficacy and safety results in PEXG and POAG eyes.

Introduction: The XEN gel stent is currently the only minimally invasive glaucoma surgical device that targets the subconjunctival outflow pathway through an ab interno placement. It has demonstrated a significant intraocular pressure (IOP)–lowering potential and a favorable safety profile compared with traditional filtering surgery. However, despite a less invasive approach, the presence of a filtering bleb inevitably implies some risk of complications. The most commonly reported bleb-related complication, with rates as high as 45%, is bleb fibrosis associated with raised IOP. To restore filtration in those failing blebs, needling revision is considered the procedure of choice. In this study, we present the results of mitomycin C–augmented needling after XEN implantation. Methods: This was a prospective, interventional study, conducted at a single tertiary glaucoma center. Fifty-one eyes of 51 patients with raised IOP associated with either a fibrotic or shallow bleb or increased vascularity following XEN gel stent implantation at the investigation site between January 2015 and June 2016 were enrolled in this study. Patients with other identified causes of filtration failure (stent malposition, internal ostium obstruction, retained viscoelastic) were excluded. Included patients who underwent mitomycin C–augmented needling revision, and follow-up examinations were conducted at 1 day, 1 week, and 1, 3, 6, 12, 18, and 24 months. The primary outcome was the magnitude of IOP reduction following needling revision at the last follow-up visit. Secondary outcome measures were the number of needling procedures carried out in all patients, the rate of patients requiring further filtering surgery following needling revision, and the rate of intraoperative and postoperative complications associated with needling revisions. Results: The average age was 74.4±9.6 years; 66.7% (n=34) were female individuals. Primary open-angle glaucoma was the most common diagnosis (n=21, 41.2%). A total of 78 needling procedures were performed over the 24-month follow-up. Overall 20 of 51 eyes (39.2%) required >1 needling revision, and 14 eyes (24.5%) eventually required reoperation to maintain IOP within their desired target range. Before XEN implantation, mean preoperative IOP was 22.3±8.2 mm Hg and decreased to 14.1±8.0 mm Hg at day 1 postoperatively (−36.8%). The last measured IOP before the first needling revision was on average 23.6±8.9 mm Hg, which reduced to a mean 12.1±4.2 mm Hg at the first postrevision appointment (−48.7%). At the last follow-up appointment, on average 17.0±7.0 months after the first needling, the mean IOP was 14.3±4.1 mm Hg (−35.9% and −39.4% from preoperative and prerevision baselines, respectively). Complications associated with needling revisions were partial amputation of the XEN implant during needling (n=2, 3.9%), hypotony with choroidal detachment (n=1, 2%), and failure to achieve target IOP requiring subsequent surgery (n=14, 27.5%). No association was found between any of the recorded characteristics and the number of needling revisions performed or their outcomes. Discussion: The present study shows that needling revision following XEN gel stent implantation is a relatively safe and efficient intervention to restore filtration in failing blebs, with a significant and durable IOP-reduction potential.

Précis: A larger proportion of iStent inject microstents than suggested by gonioscopic examination could be entirely burrowed within the trabeculum (45.7%). The length of device protrusion within the anterior chamber is linked to postoperative intraocular pressure (IOP). Introduction: The iStent inject is a relatively new device designed to be implanted ab-interno through the trabecular meshwork. Although some preliminary studies have shown IOP-lowering potential, the full extent of the mechanisms through which IOP is reduced remains unconfirmed. The aim of this study was to use in vivo optical coherence tomography analysis of the anatomic and physiological effects of iStent inject device positioning on the structures of the iridocorneal angle and IOP. Methods: In total, 25 eyes of 19 subjects (mean age, 75.5±10.5 y) with mild to moderate open-angle glaucoma were enrolled in this prospective study. All patients underwent implantation of 2 iStent inject devices combined with cataract surgery. In the postoperative period, after IOP stabilized, anterior segment optical coherence tomography (AS-OCT) was performed and several measurements were made of the Schlemm canal (SC) and the devices’ positions. Thirteen unoperated fellow eyes served as control eyes. Results: Overall, 92% of devices were visible on AS-OCT versus 88% visible on gonioscopic examination. Of all visible devices, 54.3% had a protruding portion into the anterior chamber with a mean protruding length of 88.5 µm, and 72% of the devices’ heads were not positioned within the SC, with a mean shortest distance of 109.4 µm. In operated eyes, the average major diameter of SC was 308.7±197.4 µm (median, 303.8 µm) versus 126.9±60.3 µm in control eyes. Device protrusion and larger SC diameters were associated with lower postoperative IOP (r _s=−0.54; P=0.005 and r _s=−0.43; P=0.04, respectively), whereas the distance between the devices’ heads and SC was inversely associated with SC dilatation (r _s=−0.41; P=0.04). Conclusions: This study highlights the value of AS-OCT in exploring the positioning of trabecular bypass devices such as the iStent inject. Our study shows that more microstents than suggested by gonioscopy could be completely burrowed within the trabeculum. It also suggests that the surgical outcomes of cataract surgery combined with iStent inject implantation may be connected to the amplitude of device protrusion within the anterior chamber as well as the postoperative dimensions of the SC.