Gel Stent Versus Trabeculectomy: The Randomized, Multicenter, Gold-Standard Pathway Study (GPS) of Effectiveness and Safety at 12 Months

Outcomes and baseline predictors of failure in primary standalone Xen45 gel stent vs trabeculectomy for glaucoma

PURPOSE

To compare safety, effectiveness and baseline predictors of failure in standalone primary Xen45 gel stent (Xen) vs trabeculectomy (Trab) in glaucoma.

DESIGN

Retrospective study SUBJECTS: Subjects that underwent primary Xen or Trab augmented by mitomycin-C with at least 12 months follow-up.

METHODS

Multinational observational study of eyes in the Fight Glaucoma Blindness international registry MAIN OUTCOME MEASURES: The primary outcome was success at 12 months defined by IOP reduction ≥ 20% from baseline and ≤ threshold IOPs of 15mmHg, 18mmHg and 21mmHg with (qualified) or without (complete) medications and without secondary glaucoma surgery. Multivariable mixed effects cox regression models were used to identify risk factors for failure in each cohort.

RESULTS

701 eyes (Xen, 308; Trab, 393) of 596 subjects were included with baseline IOP being significantly higher (22.4 vs 19.9 mmHg, p < 0.001) and baseline medications significantly lower in the Xen vs the Trab group (2.9 vs 3.4, p <0.001). Baseline visual field (VF) mean deviation (MD) was less severe in the Xen group (-9.47 vs -13.04 dB, p < 0.001). The proportion of complete surgical success was significantly lower in the Xen vs Trab group across the three upper IOP limits at 12 months; 32% vs 52% at 15mmHg, 37% vs 54% at 18mmHg, and 39% vs 55% at 21mmHg (p < 0.001). The incidence of post-operative numerical and symptomatic hypotony was lower in the Xen vs Trab group. In the Xen cohort, a higher failure rate was associated with Asian ethnicity (HR, 1.97; 95% CI, 1.03-3.79) and use of oral acetazolamide at baseline (HR, 1.74; 1.13-2.70), while a lower failure rate was associated with diagnosis of ocular hypertension/open angle glaucoma suspect (HR, 0.52; 0.28-0.94) and secondary open angle glaucoma (HR, 0.45; 0.25-0.8). Exposure to prostaglandin analogue was associated with greater failure in the Trab group (HR, 2.66; 1.18-6.01).

CONCLUSIONS

There was significantly greater complete success at 12 months across all complete success definitions for Trab compared to Xen, while the rate of post-operative hypotony was significantly lower in Xen group. Asian ethnicity and use of oral acetazolamide at baseline were associated with greater failure in Xen, while exposure to prostaglandin analogue was associated with greater failure in Trab patients. Such baseline predictors of success and failure may help guide patient selection for subconjunctival minimally invasive glaucoma surgery in patients undergoing surgical intervention.

Hypotony Failure Criteria in Glaucoma Surgical Studies and Their Influence on Surgery Success

PURPOSE

Review hypotony failure criteria used in glaucoma surgical outcome studies and evaluate their impact on success rates.

DESIGN

Systematic literature review and application of hypotony failure criteria to 2 retrospective cohorts.

PARTICIPANTS

A total of 934 eyes and 1765 eyes undergoing trabeculectomy and deep sclerectomy (DS) with a median follow-up of 41.4 and 45.4 months, respectively.

METHODS

Literature-based hypotony failure criteria were applied to patient cohorts. Intraocular pressure (IOP)-related success was defined as follows: (A) IOP ≤ 21 mmHg with ≥ 20% IOP reduction; (B) IOP ≤ 18 mmHg with ≥ 20% reduction; (C) IOP ≤ 15 mmHg with ≥ 25% reduction; and (D) IOP ≤ 12 mmHg with ≥ 30% reduction. Failure was defined as IOP exceeding these criteria in 2 consecutive visits > 3 months after surgery, loss of light perception, additional IOP-lowering surgery, or hypotony. Cox regression estimated failure risk for different hypotony criteria, using no hypotony as a reference. Analyses were conducted for each criterion and hypotony type (i.e., numerical [IOP threshold], clinical [clinical manifestations], and mixed [combination of numerical or clinical criteria]).

MAIN OUTCOME MEASURES

Hazard ratio (HR) for failure risk.

RESULTS

Of 2503 studies found, 278 were eligible, with 99 studies (35.6%) lacking hypotony failure criteria. Numerical hypotony was predominant (157 studies [56.5%]). Few studies used clinical hypotony (3 isolated [1.1%]; 19 combined with low IOP [6.8%]). Forty-nine different criteria were found, with IOP < 6 mmHg, IOP < 6 mmHg on ≥ 2 consecutive visits after 3 months, and IOP < 5 mmHg being the most common (41 [14.7%], 38 [13.7%], and 13 [4.7%] studies, respectively). In both cohorts, numerical hypotony posed the highest risk of failure (HR, 1.51-1.21 for criteria A to D; P < 0.001), followed by mixed hypotony (HR, 1.41-1.20 for criteria A to D; P < 0.001), and clinical hypotony (HR, 1.12-1.04; P < 0.001). Failure risk varied greatly with various hypotony definitions, with the HR ranging from 1.02 to 10.79 for trabeculectomy and 1.00 to 8.36 for DS.

CONCLUSIONS

Hypotony failure criteria are highly heterogenous in the glaucoma literature, with few studies focusing on clinical manifestations. Numerical hypotony yields higher failure rates than clinical hypotony and can underestimate glaucoma surgery success rates. Standardizing failure criteria with an emphasis on clinically relevant hypotony manifestations is needed.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Mitomycin C 0.2 mg/ml vs. Mitomycin C 0.4mg/ml during the implantation of an ab externo SIBS microshunt: A mega-analysis

PURPOSE

To compare the effectiveness and adverse event profile of standalone SIBS microshunt implantation with adjunct MMC 0.2 mg/ml and MMC 0.4 mg/ml.

DESIGN

Mega-analysis using individual patient data from international prospective and retrospective clinical studies.

STUDY POPULATION

Patients with glaucoma who underwent implantation of a SIBS microshunt with MMC as a standalone procedure.

METHODS

A comparison of eyes that received MMC 0.2 mg/ml or 0.4 mg/ml MAIN OUTCOMES MEASURES: Primary outcome was complete success defined as the proportion of eyes at one year with all of the following: (1) no two consecutive IOPs > 17 mmHg; (2) no clinical hypotony (3) ≥20% IOP reduction from baseline and (4) no use of glaucoma medications. Secondary outcomes included IOP thresholds of 12 mmHg,14 mm Hg and 21mmHg, median IOP, number of medications, risk factors for failure, interventions, adverse events, and reoperations.

RESULTS

At 1 year, the complete success rate was significantly higher (71.3% vs 50.46%, p<0.001) and the median IOP significantly lower (13.0 vs. 14.2 mmHg, p<0.05) in the MMC 0.4 mg/ml group. MMC 0.2 mg/ml was found to be a significant risk factor for failure (HR 1.75 95%CI 1.14 to 2.67). Needling and surgical revision occurred at a lower rate in the MMC 0.4 mg/ml group (7% vs. 18.8%, p= 0.002 and 4.3% vs.13.7% p= 0.0087, respectively). Adverse events occurred at a similar frequency in both groups (26.6% MMC 0.2 mg/ml vs. 29.6% MMC 0.4 mg/ml, p=0.46), most of which were early and transient.

CONCLUSION

SIBS microshunt implantation with MMC 0.4 mg/ml resulted in a higher success rate with greater IOP reduction compared to MMC 0.2 mg/ml. Higher MMC concentration was not associated with increased serious adverse events.

Using a Novel, Subconjunctival, Sustained-Release Mitomycin C Formulation in a Rabbit Model of Filtration Surgery with Gel Stent Implantation

Purpose: To investigate gel stent implantation with and without intraoperative sustained-release mitomycin C (MMC SR) in a rabbit model for gel stent implantation, and to examine aqueous humor outflow (AHO) postimplantation. Methods: Four groups of rabbits were included. Group 1 was untreated (control). Groups 2, 3, and 4 received the gel stent without MMC, with MMC solution (subconjunctival injection), and with MMC SR (subconjunctival injection), respectively. Intraocular pressure (IOP) and AHO were assessed via tonometry and indocyanine green-based angiography, respectively. The main efficacy measure was change in IOP from baseline. Results: Following gel stent implantation, Groups 2, 3, and 4 maintained ≥20% IOP reduction (response) for a median duration of 1 week, 6.5 weeks, and 30 weeks, respectively. Angiography showed normal aqueous humor drainage (Group 1) beginning at the perilimbal trabecular plexus and continuing posteriorly to episcleral outflow vessels. Following implantation, drainage occurred preferentially and directly into the subconjunctival bleb. Conclusions: Gel stent implantation with MMC SR was most effective in achieving sustained, long-term IOP reduction in the rabbit model, compared with implantation with or without MMC solution. Bleb presence and the postimplantation aqueous angiography results indicated redirection of the AHO to the subconjunctival vasculature and presumed lymphatics, suggesting efficient glaucoma filtration to lower IOP in this model. This rabbit model and aqueous angiography may help refine understanding of the mechanism of action of minimally invasive glaucoma surgeries and ultimately translate to improved surgical devices and procedures for patients with glaucoma.

Swiss Multicenter Ab Interno XEN45 Gel Stent Study: 2-Year Real-World Data

INTRODUCTION

The aim of this study was to investigate the 2-year postoperative efficacy of the XEN45 Gel Stent by evaluating the reduction of intraocular pressure (IOP) and the need for eye pressure-lowering medications in a multicenter setting in Switzerland.

METHODS

Patients with various types of glaucoma who received a XEN45 Gel Stent with or without combined phacoemulsification cataract surgery at five hospitals in Switzerland were retrospectively enrolled. Pre- and postoperative IOP, the number of antiglaucoma medications, and the need of subsequent interventions to control IOP were assessed. The success rate was defined as a ≥ 20% reduction of IOP 2 years postoperatively without the need for subsequent glaucoma surgery.

RESULTS

A total of 345 eyes were included: 44.3% with primary open-angle, 42.0% pseudoexfoliation, and 13.7% with other types of glaucoma. Of these, 206 patients were followed for 2 years. Preoperatively, the mean IOP was 26.3 ± 8.9 mmHg and the mean number of antiglaucoma medications administered was 3.0 ± 1.3. Two years postoperatively, the success rate was 66.0% (95% confidence interval 59.3-72.1%), the IOP had dropped by 43.8% to 14.8 ± 5.7 mmHg, and the number of medications was reduced by a mean of 2.0 ± 1.7 per day. Postoperative complications and the need for interventions remained low.

CONCLUSION

The XEN45 Gel Stent successfully reduced IOP and the number of antiglaucoma drugs in most patients at 2 years postoperatively.

Two-year outcomes of Xen 45 gel stent implantation in patients with open-angle glaucoma: real-world data from the Fight Glaucoma Blindness registry

OBJECTIVE

To evaluate efficacy and safety outcomes of the Xen 45 gel stent implant over 24 months of follow-up.

METHODS

A retrospective analysis of prospectively collected data from the Fight Glaucoma Blindness observational registry. Complete success (CS) was defined as intraocular pressure (IOP) reduction ≥20% from preoperative and an IOP ≤18 mm Hg and ≥6 mm Hg with no secondary procedure at 2 years and without IOP-lowering medications. Qualified success (QS) was defined similarly, allowing the use of IOP-lowering medications.

RESULTS

The Xen 45 gel stent implant was implanted in 646 eyes of 515 patients. Preoperative IOP was 21.4±7.6 (mean±SD) mm Hg on 2.7±1.3 IOP-lowering medication and mean deviation was -10.2±8.4 dB. After 24-month follow-up, IOP was 16.8±7.3 mm Hg (mean reduction of 21.7%) on 1.2±1.4 IOP-lowering medications. CS and QS rates at 24 months were 26% and 48%, respectively. CS and QS were higher in the Xen stand-alone group (33% and 52%, respectively) than in the Xen+cataract group (16% and 42%, respectively). Bleb needling was performed in 28.4% of cases, and 18% underwent a secondary procedure.

CONCLUSIONS

The Xen 45 gel stent implant offers acceptable long-term efficacy for the treatment of open-angle glaucoma. However, there is a significant rate of reoperation and needling, and outcomes are less effective if combined with cataract surgery.

Comparing Outcomes of Trabeculectomy with Mitomycin C to 45 μm Gelatin Stent Placed Ab Externo with Open Conjunctiva

PURPOSE

To compare trabeculectomy with mitomycin C (trab-MMC) and XEN45 Gel Stent placed ab externo with open conjunctiva (XGS AEO) with or without cataract surgery in patients with glaucoma.

DESIGN

Nonrandomized, retrospective, comparative study.

SUBJECTS

A total of 204 eyes from 204 glaucoma patients who received XGS AEO or underwent trab-MMC with or without cataract surgery between July 2018 and August 2021 at Massachusetts Eye and Ear.

METHODS

Visits from 204 patient charts were reviewed after either trab-MMC or XGS AEO from 2018 to 2021 from a level 3 triage center.

MAIN OUTCOME MEASURES

Intraocular pressure (IOP), medication burden, Kaplan-Meier success rates, 5-fluorouracil impact, and complications.

RESULTS

One hundred fifty-seven patients underwent trab-MMC and 47 underwent XGS AEO. Groups had similar baseline intraocular pressure (IOP) and medications (meds). Intraocular pressure and meds decreased similarly at 1.5 years (11.2 mmHg vs. 7.4 mmHg, P = 0.62; 2.9 vs. 2.8 meds, P = 0.92, respectively for trab-MMC and XGS AEO). Success was defined as IOP reduction ≥ 20% with 5 mmHg ≤ IOP ≤ 18 mmHg for 2 consecutive visits. Complete success (CS) did not allow meds; qualified success (QS) allowed for ≤ baseline meds. When IOP fluctuations in the first 60 days were not counted as failures, CS was 43% for trab-MMC, about 8.5% higher than for XGS AEO (P < 0.01). Qualified success was similar between the groups (65%-67%). Procedure time was shorter for XGS AEO than trab-MMC (44 vs. 63 minutes, P < 0.01).

CONCLUSIONS

XEN45 Gel Stent AEO may provide similar benefits to trab-MMC, especially for patients who tolerate some meds, with shorter procedure times.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Navigating hypotony challenges with XEN gel implantation

INTRODUCTION

The XEN Gel, a hydrophilic tube meticulously crafted to adhere to the principles of the Hagen - Poiseuille law, is designed to facilitate efficient aqueous shunting without inducing hypotony. Implantable ab interno or ab externo, with or without conjunctival opening, the device shows no significant outcome differences. Despite numerical hypotony signaling failure, patients may fare well below 6 mmHg.

AREAS COVERED

This review provides insights into device variability, challenges related to hypotony, associated risk factors, and hypotony management.

EXPERT OPINION

The progressive evolution of the XEN Gel constitutes a significant advancement in the field of glaucoma management. Comparative studies investigating diverse implantation methodologies, particularly the ab interno and closed conjunctival approaches, highlight the device versatility in addressing individual patient needs. Exploring hypotony from both statistical and clinical perspectives challenges the traditional view of intraocular pressure as a straightforward success or failure indicator. The incidence of hypotony-related issues varies between device models, emphasizes the need for an individualized approach during device selection. Overall, understanding the dynamics of hypotony is crucial for optimizing the outcomes of XEN Gel implantation.

Glaucoma surgical procedures under development

PURPOSE OF REVIEW

Rapid innovation in glaucoma surgery is expanding surgical options in the angle, subconjunctival space, and supraciliary space.

RECENT FINDINGS

Advancements in glaucoma surgery make it possible for surgeons to provide treatments with less risk. In particular, new devices and lasers are available for minimally invasive glaucoma surgeries. There are also new implants and techniques for bleb-forming glaucoma surgery.

SUMMARY

As glaucoma surgeons have access to an increasing number of procedures, devices, and treatments, it is important for evidence to drive decision-making.

European Glaucoma Society - A guide on surgical innovation for glaucoma

PROLOGUE: Glaucoma surgery has been, for many decades now, dominated by the universal gold standard which is trabeculectomy augmented with antimetabolites. Tubes also came into the scene to complement what we use to call conventional or traditional glaucoma surgery. More recently we experienced a changing glaucoma surgery environment with the "advent" of what we have become used to calling Minimally Invasive Glaucoma Surgery (MIGS). What is the unmet need, what is the gap that these newcomers aim to fill? Hippocrates taught us "bring benefit, not harm" and new glaucoma techniques and devices aim to provide safer surgery compared to conventional surgery. For the patient, but also for the clinician, safety is important. Is more safety achieved with new glaucoma surgery and, if so, is it associated with better, equivalent, or worse efficacy? Is new glaucoma surgery intended to replace conventional surgery or to complement it as an 'add-on' to what clinicians already have in their hands to manage glaucoma? Which surgery should be chosen for which patient? What are the options? Are they equivalent? These are too many questions for the clinician! What are the answers to the questions? What is the evidence to support answers? Do we need more evidence and how can we produce high-quality evidence? This EGS Guide explores the changing and challenging glaucoma surgery environment aiming to provide answers to these questions. The EGS uses four words to highlight a continuum: Innovation, Education, Communication, and Implementation. Translating innovation to successful implementation is crucially important and requires high-quality evidence to ensure steps forward to a positive impact on health care when it comes to implementation. The vision of EGS is to provide the best possible well-being and minimal glaucomainduced visual disability in individuals with glaucoma within an affordable healthcare system. In this regard, assessing the changes in glaucoma surgery is a pivotal contribution to better care. As mentioned, this Guide aims to provide answers to the crucial questions above. However, every clinician is aware that answers may differ for every person: an individualised approach is needed. Therefore, there will be no uniform answer for all situations and all patients. Clinicians would need, through the clinical method and possibly some algorithm, to reach answers and decisions at the individual level. In this regard, evidence is needed to support clinicians to make decisions. Of key importance in this Guide is to provide an overview of existing evidence on glaucoma surgery and specifically on recent innovations and novel devices, but also to set standards in surgical design and reporting for future studies on glaucoma surgical innovation. Designing studies in surgery is particularly challenging because of many subtle variations inherent to surgery and hence multiple factors involved in the outcome, but even more because one needs to define carefully outcomes relevant to the research question but also to the future translation into clinical practice. In addition this Guide aims to provide clinical recommendations on novel procedures already in use when insufficient evidence exists. EGS has a long tradition to provide guidance to the ophthalmic community in Europe and worldwide through the EGS Guidelines (now in their 5th Edition). The EGS leadership recognized that the changing environment in glaucoma surgery currently represents a major challenge for the clinician, needing specific guidance. Therefore, the decision was made to issue this Guide on Glaucoma Surgery in order to help clinicians to make appropriate decisions for their patients and also to provide the framework and guidance for researchers to improve the quality of evidence in future studies. Ultimately this Guide will support better Glaucoma Care in accordance with EGS's Vision and Mission. Fotis Topouzis EGS President

[Review by the French Glaucoma Society on the roles of new surgical techniques in glaucoma]

The surgical management of glaucoma has been enriched in recent years by the arrival of new surgical techniques as a group known as MIGS (minimally invasive glaucoma surgery). The objective of these new techniques is to reduce intraocular pressure (IOP) while limiting the risk of complications of conventional filtering surgery and allowing faster visual recovery. MIGS can be classified into three main categories depending on the route used to promote the outflow of aqueous humor: the trabecular route, the suprachoroidal route and the subconjunctival route. MIGS using the subconjunctival route are also called minimally invasive bleb surgery (MIBS). These new techniques do not replace conventional filtering surgery, which remains the gold standard technique, but now offer new alternatives for the surgical management of glaucoma patients in combination with cataract surgery or as stand-alone procedures.

New Devices in Glaucoma

Glaucoma remains a leading cause of blindness globally. Minimally invasive treatment techniques are rapidly expanding the availability of therapeutic options for glaucoma. These include devices aimed at enhancing outflow through the subconjunctival space, Schlemm's canal, and suprachoroidal space, sustained-release drug delivery devices, and extraocular devices aiming to reduce glaucomatous progression through other novel means. In this review, we provide an overview of several novel devices either newly available or in development for the medical and surgical management of glaucoma. Further studies are required to determine the long-term efficacy of these devices and how they will integrate into the current landscape of glaucoma management.

Effectiveness and Safety of Xen Gel Stent in Glaucoma Surgery: A Systematic Review of the Literature

Although topical medical therapy and selective-laser-trabeculoplasty represent the treatments of choice to reduce intraocular pressure, many patients do not achieve adequate glaucoma control; therefore, they require further options and eventually surgery. Trabeculectomy is still considered the gold standard, but the surgical management of glaucoma has undergone continuous advances in recent years, XEN-gel-stent has been introduced as a safer and less traumatic means of lowering intraocular pressure (IOP) in patients with open-angle glaucoma (OAG). This study aimed to review the effectiveness and safety of clinical data on XEN-stent in OAG patients with a Synthesis-Without-Meta-analysis (SWiM) methodology. A total of 339 studies were identified following a literature search adhering to PRISMA guidelines and, after evaluation, 96 studies are discussed. XEN63 and XEN45 device data were collected both short and long term. In addition, this document has evaluated different aspects related to the XEN implant, including: its role compared to trabeculectomy; the impact of mitomycin-C dose on clinical outcomes; postoperative management of the device; and the identification of potential factors that might predict its clinical outcomes. Finally, current challenges and future perspectives of XEN stent, such as its use in fragile or high myopia patients, were discussed.

Managing primary open-angle glaucoma in the setting of suboptimal surgical outcomes in the fellow eye

A 62-year-old woman with mild myopia presented to her local optometrist for a routine examination and was found to have intraocular pressure (IOP) of 30 mm Hg in both eyes and cupped nerves. She had a family history of glaucoma in her father. She was started on latanoprost in both eyes and was referred for a glaucoma evaluation. On initial evaluation, her IOP was 25 mm Hg in the right eye and 26 mm Hg in the left eye. Central corneal thickness measured 592 µm in the right eye and 581 µm in the left eye. Her angles were open to gonioscopy without any peripheral anterior synechia. She had 1+ nuclear sclerosis with a corrected distance visual acuity (CDVA) of 20/25 in the right eye and 20/30- in the left eye and uncorrected near visual acuity of J1+ in each eye. Her nerves were 0.85 mm in the right eye and 0.75 mm in the left eye. Optical coherence tomography (OCT) showed retinal nerve fiber layer thinning and a dense superior arcuate scotoma into fixation in her right eye, and superior and inferior arcuate scotomas in her left eye (Figures 1 and 2JOURNAL/jcrs/04.03/02158034-202307000-00019/figure1/v/2023-06-26T195222Z/r/image-tiffJOURNAL/jcrs/04.03/02158034-202307000-00019/figure2/v/2023-06-26T195222Z/r/image-tiff, Supplemental Figures 1 and 2, available at http://links.lww.com/JRS/A882 and http://links.lww.com/JRS/A883). She was successively trialed on fixed combination brimonidine-timolol, dorzolamide, and netarsudil, in addition to her latanoprost, but her IOP remained in the mid- to upper 20s in both eyes. The addition of acetazolamide lowered the pressure to 19 mm Hg in both eyes, but she tolerated it poorly. Methazolamide was also attempted with similar side effects. We elected to perform left eye cataract surgery combined with 360-degree viscocanaloplasty and insertion of a Hydrus microstent (Alcon Laboratories, Inc.). Surgery was uncomplicated with IOP of 16 mm Hg on postoperative day 1 with no glaucoma medications. However, by postoperative week 3, IOP returned to 27 mm Hg, and despite restarting latanoprost-netarsudil and finishing her steroid taper, IOP remained at 27 mm Hg by postoperative week 6. Brimonidine-timolol was added back to her left eye regimen and at postoperative week 8, IOP had elevated to 45 mm Hg. Maximizing her therapy with the addition of topical dorzolamide and oral methazolamide brought her IOP back down to 30 mm Hg. At that point, the decision was made to proceed with trabeculectomy of the left eye. The trabeculectomy was uneventful. However, postoperative attempts to augment filtration were rendered less successful by extremely thick Tenon layer. At her most recent follow-up the pressure in the left eye was mid-teens with brimonidine-timolol and dorzolamide. Her right eye IOP is in the upper 20s on maximum topical therapy. Knowing her postoperative course in the left eye, how would you manage the right eye? In addition to currently available options, would you consider a supraciliary shunt such as the MINIject (iSTAR) if such a device were U.S. Food and Drug Administration (FDA)-approved?