Chronic Intraocular Inflammation as a Risk Factor for XEN Gel Stent Occlusion: A Case of Microscopic Examination of a Fibrin-obstructed XEN Stent

Complications of XEN gel stent implantation for the treatment of glaucoma: a systematic review

Aim

This study was aimed to summarize the complications and their management associated with XEN gel stent implantation.

Methods

A systematic review of literature was conducted using Medline (via PubMed), EMBASE, the Cochrane Library databases, and China National Knowledge Infrastructure, from their inception to February 1, 2024.

Results

A total of 48 studies published between 2017 and 2024 were identified and included in the systematic review, including 16 original studies (retrospective or prospective clinical studies), 28 case reports, and 4 case series, which followed patients for up to 5 years. Early postoperative complications of XEN gel stent implantation include hypotony maculopathy (1.9-4.6%), occlusion (3.9-8.8%), suprachoroidal hemorrhage (SCH), choroidal detachment (0-15%), conjunctival erosion, and exposure of the XEN gel stent (1.1-2.3%), wound and bleb leaks (2.1%) and malignant glaucoma (MG) (2.2%). Mid-postoperative complications of XEN gel stent implantation included migration of XEN (1.5%), ptosis (1.2%), endophthalmitis (0.4-3%), macular edema (1.5-4.3%), hypertrophic bleb (8.8%) and subconjunctival XEN gel stent fragmentation (reported in 2 cases). Late postoperative complications reported in cases included spontaneous dislocation and intraocular degradation.

Conclusion

XEN gel stent implantation is a minimally invasive glaucoma surgery (MIGS) procedure for glaucoma, known for its potential to minimize tissue damage and reduce surgical duration. However, it is crucial to note that despite these advantages, there remains a risk of severe complications, including endophthalmitis, SCH, and MG. Therefore, postoperative follow-up and early recognition of severe complications are essential for surgical management.

Recanalization of Xen45 gel stent implant occlusion using 10 - 0 nylon suture in refractory glaucoma: a case report

BACKGROUND

Xen Gel Stent implant is a new minimally invasive surgical treatment for glaucoma that has been proven effectiveness and safety profile. However, it may also lead to some complications. Xen Gel Stent occlusion is a relatively rare complication reported less frequently and has limited treatment experience. In our case report, we proposed a novel surgical treatment using a 10 - 0 nylon suture to successfully recanalize the occluded Xen45 Gel Stent.

CASE PRESENTATION

A 16-year-old female patient had bilateral juvenile glaucoma for the past 5 years. Her right eye had undergone three glaucoma surgeries but failed. At a presentation to our hospital, the right eye's intraocular pressure (IOP) was 30 mmHg despite applying four different active principles. Xen45 Gel Stent implant was chosen for treatment, but six days after implantation, the IOP rose to 40 mmHg as a result of an anterior chamber tip occlusion of the Xen45 Gel Stent. Nd: YAG laser shockwave therapy was attempted but failed. The patient eventually had to return to the operating room for a revision procedure. The Xen45 Gel Stent was recanalized from the ab externo by making an L-shaped conjunctival incision at the fornix base and threading a 10 - 0 nylon suture through it. The IOP was successfully controlled in the 11-month follow-up without medication.

CONCLUSION

If postoperative occlusion arises after Xen45 Gel Stent implantation, surgery using 10 - 0 nylon suture to recanalize Xen45 Gel Stent should be considered as a relatively safe, effective that does not require removal of Xen45 Gel Stent.

Foreign body reaction after CyPass® Micro-Stent implantation: a case series

PURPOSE

To retrospectively assess the histopathological particularities of explanted CyPass® Micro-Stent of patients with significant loss of endothelial cell density.

METHODS

This is a case series of fourteen eyes from eleven patients who underwent CyPass® Micro-Stent implantation due to mild to moderate glaucoma and who subsequently suffered from loss of endothelial cell density. Therefore, the explantation of the device was necessary. In addition to the retrospective evaluation of the intraocular pressure and the endothelial cell density at the time of implantation and explantation, every surgically removed implant was histologically examined and evaluated.

RESULTS

Fourteen eyes of eleven patients were in total analysed. The patients-seven males and four females-had a mean age of 62.9 years. The average time between CyPass implantation and explantation was 3.7 years. Eight patients suffered from primary-open-angle glaucoma (POAG), while two patients had a pseudoexfoliation glaucoma (PXG) and one patient had low-pressure glaucoma. Ten of the patients were already pseudophakic before the CyPass implantation and four patients underwent previously glaucoma interventions. There was a significant reduction in the intraocular pressure from 18.57 ± 5.27 mmHg at the time of implantation to 14.78 ± 3.32 mmHg at the time of explantation (p = 0.037). The average endothelial cell density decreased from 1843.67 ± 421.81 to 932.92 ± 412.86/mm² at the time of explantation (p < 0.01). The histological findings showed a fibrous obliteration of the CyPass accompanied by a chronic granulomatous inflammation with giant cell macrophages. Histologically, these findings were consistent with a foreign body granuloma.

CONCLUSIONS

Implants made of polyimides such as the CyPass® Micro-Stent are considered to be biocompatible, but there is no guarantee not to be obliterated or encapsulated. This is the first case series that has detected a foreign body granuloma in multiple eyes after CyPass implantation. However, there is no connection with the type of glaucoma, the extent of previous operations or with the presence of a prolonged postoperative inflammatory reaction.

A Comprehensive Review of Pediatric Glaucoma Following Cataract Surgery and Progress in Treatment

Glaucoma following cataract surgery (GFCS) remains a serious postoperative complication of pediatric cataract surgery. Various risk factors, including age at lensectomy, intraocular lens implantation, posterior capsule status, associated ocular/systemic anomaly, additional intraocular surgery, and a family history of congenital cataract and GFCS, have been reported. However, the optimal surgical approach remains unclear. This review evaluates the diagnostic criteria, classification, risk factors, mechanism, and surgical management, especially the efficacy of minimally invasive glaucoma surgery, in GFCS, and aims to propose an optimal clinical management strategy for GFCS. The results of our review indicate that ab interno trabeculotomy (goniotomy) may be the most appropriate first-line treatment for GFCS.

Outcomes of Deep Sclerectomy following Failed XEN Gel Stent Implantation in Open-Angle Glaucoma: A Prospective Study

Background: The purpose of this study is to evaluate the outcome of deep sclerectomy (DS) as a secondary procedure following failed ab-interno XEN gel stent implantation in patients with open-angle glaucoma. Methods: Prospective, single-center, non-randomized, interventional study. Consecutive eyes that underwent mitomycin C (MMC) augmented XEN gel stent surgery, with uncontrolled intraocular pressure (IOP) or signs of disease progression, were included to undergo MMC-augmented DS. Primary efficacy outcome was surgical success, defined as complete when the unmedicated IOP was 12 mmHg or less, or 15 mmHg or less and 20% lower than at the timing of XEN failure and defined as qualified when the IOP fulfilled the same conditions with fewer medications than before deep sclerectomy. Secondary measures were mean reduction in IOP and in the number of medications, and the rates of complications. Results: Seventeen eyes were enrolled with a mean age of 72.1 ± 8.2 years (66.7% women). The mean follow-up was 20.1 ± 4.9 months, with more than 12-month data available from 15 eyes. Following DS, IOP decreased significantly from 22.6 ± 5.3 mmHg to 12.3 ± 5.5 (45.6%; p < 0.001). Antiglaucoma medications dropped from 1.1 ± 0.9 to 0.3 ± 0.7. Complete success was obtained in 40% of eyes using the threshold of 12 mmHg or less and a 20% decrease of IOP, and in 60% using the 15 mmHg or less threshold. Adverse events were observed in 20% of eyes (bleb leakage (13.3%); hypotony (6.7%)). No cases of choroidal detachment or hypotony maculopathy were reported. Conclusions: Failed XEN gel stent implantation does not seem to negatively affect the safety and efficacy of subsequent deep sclerectomy surgery.

Minimally invasive glaucoma surgery in childhood glaucoma

PURPOSE OF REVIEW

Minimally invasive glaucoma surgery (MIGS) has been shown to be safe and effective in treatment of mild to moderate glaucoma in adults, but reports in childhood glaucoma are limited. We review the available data concerning MIGS and discuss its potential role in childhood glaucoma management.

RECENT FINDINGS

Ab interno counterparts to circumferential ab externo trabeculotomy such as gonioscopy-assisted transluminal trabeculotomy (GATT) and Trab360 show promise in treatment of primary glaucomas as reported in a few retrospective case series. Kahook Dual Blade (KDB) and Trabectome have demonstrated mixed results in few published case reports in children. Small case series and reports suggest that the Xen gel stent can be a safer alternative to traditional filtration surgery, though data on long-term implant and bleb stability are unavailable. Newer devices are being investigated and early results are encouraging.

SUMMARY

GATT and Trab360 seem to be safe, effective methods of achieving circumferential trabeculotomy in childhood glaucoma. KDB, Trabectome, and Xen gel stent have shown some success in selected cases with short-term follow-up. Surgeons must determine the risks and benefits of MIGS over more established methods of intraocular pressure reduction for each individual child. Further research is needed to validate initial findings regarding MIGS in childhood glaucoma.

Xen45 gel stent ab interno trimming for ostium occlusion: case report

BACKGROUND

Despite the XEN gel stent low-risk profile, various complications following the implant have been described, including internal and external occlusion, with a consequent postoperative rise in intraocular pressure (IOP). In this case report we aimed to present a XEN45 stent internal occlusion successfully treated by trimming in situ its proximal end with a 25 G vitreous scissors using a bimanual technique.

CASE PRESENTATION

A 63-year-old male patient affected by primary open angle glaucoma (IOP = 25 mmHg) and a full thickness macular hole in his right eye, underwent ab-interno Xen gel stent implantation and, 1 month later, a 25 G vitrectomy surgery. Despite a significant IOP reduction after stent implant, 6 days after vitrectomy, IOP increased (25 mmHg) and the conjunctival bleb flattened following occlusion of stent internal ostium by a clot of presumed fibrinous material. The Nd:YAG laser failed to remove the clot, so that we decided to snip a small bit of the proximal end of the Xen tube (about 0,5 mm length) with a 25 G vitreous scissors, using a bimanual technique. In the postoperative day 1 and month 1, the IOP was 8 mmHg and 12 mmHg, respectively. The Anterior Segment OCT confirmed a functional, layered, filtering bleb, and the normal appearance and patency of the XEN proximal segment. No side effects from the intervention were observed.

CONCLUSIONS

Ab interno trimming with vitreous scissors of the occluded proximal end of the XEN stent may represent a safe, rapid and efficient method to restore aqueous humor subconjunctival drainage.

Iris-Occlusion of XEN Gel Stent following Ab Externo Transconjunctival Implantation Technique

The use of minimally invasive glaucoma surgery (MIGS) devices has become increasingly common for the management of elevated intraocular pressure (IOP) in the context of glaucoma. These technologies have traditionally been associated with fewer postoperative complications than conventional surgical techniques. However, we report on a rare case of transient XEN occlusion associated with pupil dilation following XEN gel stent implantation. This case highlights that in future XEN implantations, it may be preferable to position the XEN at a lesser angle to the iris to prevent such an occlusion. The use of different positionings of XEN is performed to optimize outcomes. However, it is highlighted that complications may arise in certain circumstances.

Minimally Invasive Glaucoma Surgery: A Critical Appraisal of the Literature

Micro- or minimally invasive glaucoma surgeries (MIGS) have been the latest addition to the glaucoma surgical treatment paradigm. This term refers not to a single surgery, but rather to a group of distinct procedures and devices that aim to decrease intraocular pressure. Broadly, MIGS can be categorized into surgeries that increase the trabecular outflow [Trabectome, iStent (first and second generations), Hydrus microstent, Kahook Dual Blade and gonioscopy-assisted transluminal trabeculotomy], surgeries that increase suprachoroidal outflow (Cypass microstent and iStent Supra), and conjunctival bleb-forming procedures (Xen gel stent and InnFocus microshunt). Compared to traditional glaucoma surgeries, such as trabeculectomy and glaucoma drainage device implantation (Ahmed, Baerveldt, and Molteno valves), MIGS are touted to have less severe complications and shorter surgical time. MIGS represent an evolving field, and the efficacy and complications of each procedure should be considered independently, giving more importance to high-quality and longer-term studies.

Rescue of Failed XEN-45 Gel Implant by Nd:YAG Shock Wave to Anterior Chamber Tip to Dislodge Hidden Intraluminal Occlusion

PURPOSE

The purpose of this study was to inform ophthalmic surgeons in a timely manner of the hidden problem of clear intraluminal cellular debris as a cause for XEN-45 failure and to describe low energy neodymium-doped yttrium aluminum garnet (Nd:YAG) laser revision with periluminal anterior chamber tip shockwave treatment to improve flow to the bleb.

PATIENTS AND METHODS

Six patients with visibly patent stent lumen post XEN-45 surgery. These eyes developed rising intraocular pressure (IOP) with a history of excellent prior bleb formation and were treated successfully with Nd:YAG laser shockwave therapy to disperse assumed intraluminal cellular debris. The laser was aimed just anterior and axial to the intracameral tip of the gel stent through a gonioscopy lens.

RESULTS

Six patients with an average age of 75 years (60 to 90 y), preoperative IOP of 30 mm Hg (16 to 52 mm Hg) on an average of 2 antiglaucoma medications (0 to 4) underwent periluminal anterior chamber tip shock wave at an average of 12 months (1 to 38 mo) from XEN-45 surgery. The IOP was immediately reduced to an average of 15 mm Hg (8 to 23 mm Hg) and last IOP averaged 15 mm Hg (10 to 23 mm Hg) on 1.5 medications (0 to 4) at 4 months post periluminal anterior chamber tip shock wave.

CONCLUSION

Nd:YAG laser revision of hidden blockage of a XEN-45 gel implant with periluminal anterior chamber tip shockwave treatment can disperse invisible intraluminal cellular debris and improve flow in a failing XEN-45 microstent, especially when distal fibrosis is not excessive.

Combined and stand-alone XEN 45 gel stent implantation: 3-year outcomes and success predictors

PURPOSE

To evaluate the 3-year treatment outcomes of XEN 45 gel stent in open-angle glaucoma patients.

METHODS

In this prospective, single-centre interventional study, consecutive eyes with uncontrolled intraocular pressure (IOP) or signs of disease progression despite medical treatment underwent XEN implantation either alone or combined with phacoemulsification (Phaco + XEN).

MAIN OUTCOME MEASURES

Surgical success was defined as 'complete' when 36-month unmedicated IOP was ≤15 mmHg with a relative IOP reduction ≥ 20% from medicated baseline, while the definition of qualified success allowed no more medications than at baseline. Other definitions of success with different IOP thresholds were also analysed. Secondary outcomes included mean IOP reduction, changes in ocular hypotensive medications and rates of reoperations.

RESULTS

Out of 149 eyes initially included, 92 eyes (61.7%) of 68 patients had complete 3-year data (XEN: n = 26; Phaco + XEN: n = 66) after 38.2% were lost to follow-up. Mean age was 76.3 ± 9.1 years, and 66.2% were female. Mean medicated IOP decreased from 20.8 ± 7.4 mmHg (21.0 ± 7.4 [XEN] vs. 20.0 ± 6.9 mmHg [Phaco + XEN]) at baseline to 13.1 ± 3.4 mmHg (12.9 ± 2.9 [XEN] vs. 12.9 ± 3.4 [Phaco + XEN]) at 3 years (-37.0%; p < 0.001). Medications decreased from 1.9 ± 1.3 (2.4 ± 1.5 [XEN] vs. 1.9 ± 1.2 [Phaco + XEN]) to 0.4 ± 0.9 (0.3 ± 0.8 [XEN] vs. 0.5 ± 0.9 [Phaco + XEN]) (-78.9%; p < 0.001). Complete success and qualified success were achieved in 29.0% and 31.0% of eyes, respectively. Needling revision was performed in 51 eyes (55.4%), and 26.1% underwent reoperations. Risk factors for surgical failure included male gender (odds ratio [OR]:3.6; p = 0.03), diagnosis of POAG (OR: 4.5; p < 0.01) and undergoing needling revision (OR: 4.6; p < 0.01). While the type of procedure had no effect on the outcomes of PEXG, POAG eyes undergoing combined surgery had significantly higher rates of failure (OR: 7.29; p = 0.023). Most patients stable at 12-month remained so through to 3 years.

CONCLUSIONS

At 3 years, XEN gel stent implantation achieved clinically significant IOP and medication reduction despite relatively high rates of needling and reoperations. Identifying patients at risk preoperatively may help optimize surgical outcomes.

Safety profile of minimally invasive glaucoma surgery

PURPOSE OF REVIEW

This article reviews the safety profile of trabecular meshwork/Schlemm's canal-based, subconjunctival, and suprachoroidal minimally invasive glaucoma surgery (MIGS).

RECENT FINDINGS

Prospective randomized clinical trials and metaanalyses published during the 2019-2020 review period provided important data regarding the safety profile of trabecular meshwork/Schlemm's canal-based MIGS. Transient hyphema and intraocular pressure spikes are among the most common complications associated with this category of MIGS, but more serious adverse events such as cyclodialysis cleft formation may also occur. Trabecular bypass microstents and the intracanalicular scaffold are further subject to device-related complications, including malposition and obstruction. Recent case reports and retrospective case series have further characterized the safety profile of the subconjunctival gel stent, with adverse events ranging from self-limited hypotony to visually devastating endophthalmitis and suprachoroidal hemorrhage. Five-year results of the COMPASS XT study demonstrated significantly greater endothelial cell loss in patients randomized to receive CyPass Micro-Stent (Alcon Laboratories, Fort Worth, TX, USA) in combination with cataract surgery versus those who underwent cataract surgery alone, and ultimately led to a Food and Drug Administration Class I recall of the device.

SUMMARY

Trabecular meshwork/Schlemm's canal-based procedures are generally among the safest MIGS, with mostly self-limited and nonvision-threatening complications. Subconjunctival gel stent insertion is associated with both bleb-related and stent-specific adverse events, which are similar to those observed with trabeculectomy and tube shunt surgery, respectively. Removal of the CyPass Micro-Stent from the market underscores the need for high-quality, long-term safety data regarding MIGS.

Ab-Externo Implantation of XEN Gel Stent for Refractory Steroid-Induced Glaucoma After Lamellar Keratoplasty

The hazy corneal donor-recipient interface after corneal transplant may cause difficulties when implanting the XEN gel stent via ab-interno approach. We aim to describe XEN gel stent implantation via ab-externo approach in refractory steroid-induced glaucoma after corneal lamellar keratoplasty. Under local anaesthesia, the XEN injector needle was inserted 7 mm behind the limbus with the bevel facing up, directly beneath the conjunctiva and advanced to the marked 2.5 mm scleral entry wound. The needle then pierced the sclera until the needle tip was just visible in the anterior chamber (AC). The slider was pushed until the tip of the XEN stent was seen in the AC. The needle was slowly withdrawn while still pushing the slider to complete stent deployment. Subconjunctival Mitomycin C 0.01% (30 µg/0.3 mL) was then injected posterior to the bleb. Three eyes of three patients with steroid-induced glaucoma after lamellar keratoplasty underwent XEN gel stent implantation via ab-externo approach placed at the superotemporal quadrant. Pre-operatively, all patients had uncontrolled IOP between 30-45 mmHg despite maximum medications and selective laser trabeculoplasty. After XEN gel stent implantation, IOP ranged between 10-17 mmHg with one or two topical antiglaucoma at 12 months. Complications include hypotony maculopathy, stent migration and hyphaema, all of which were successfully managed. Corneal graft remained clear at 12 months. XEN gel stent implantation via ab-externo approach is able to achieve good intraocular pressure (IOP) control without compromising cornea graft in patients with steroid-induced glaucoma after lamellar keratoplasty at 12 months.

Laser Iridoplasty to Treat Iris-occluded XEN Gel Stent

PURPOSE

To provide the first report on argon laser peripheral iridoplasty (ALPI) to restore XEN-45 Gel stent patency after iris occlusion.

METHODS

Case description, laser technique, and relevant clinical imaging.

RESULTS

A 53-year-old African American male patient presented with progressive advanced stage primary open-angle glaucoma. Initial intraocular pressure (IOP) was 40 mm Hg, which continued to be elevated despite maximal medical therapy and selective laser trabeculoplasty. The patient underwent an uncomplicated XEN-45 Gel stent implantation and presented with an IOP of 4 mm Hg 5 days postoperatively with a functioning bleb. On postoperative day 10, the XEN lumen was found to be occluded by the iris with an IOP spike of 39 mm Hg. Anti-glaucoma treatment to induce miosis and liberate the stent was unsuccessful. ALPI was attempted to relieve the obstruction. IOP dropped to 26 mm Hg immediately post-ALPI and continued to be well-controlled 6 months later (11 mm Hg).

CONCLUSIONS

ALPI can effectively restore XEN Gel stent patency if occluded by the iris and should be considered before attempting more invasive surgical revisions.

XEN-augmented Baerveldt surgical success rate and comparison with the Ahmed Valve

PURPOSE

The Baerveldt-XEN technique is intended to reduce the risk of early hypotony after Baerveldt implant, while keeping a good long-term intra-ocular pressure (IOP) control. The aim of this study is to discuss the surgical success rate of the Baerveldt-XEN and compare it with the commercially available flow-restrictor device (Ahmed glaucoma valve - AGV).

METHODS

Single-centre, cohort study. Consecutive glaucoma patients with uncontrolled IOP > 21 mmHg on maximum tolerated medical therapy, and who had an aqueous shunt as the planned surgical procedure. Patients underwent implantation of Baerveldt-XEN. An age-, gender- and glaucoma aetiology-matched database of AGV patients was used for comparison. Complete surgical success was defined as a final IOP between 6 and 21 mmHg, and 20% reduction from baseline with no need for IOP-lowering medication. Qualified success was the same criteria but resorting to medications.

RESULTS

Twenty-four eyes from 24 subjects with glaucoma were included in this study, 12 patients underwent Baerveldt-XEN implantation and 12 AGV. Twelve months after the Baerveldt-XEN implant, the IOP reduced from 33 ± 9 mmHg to 14 ± 3 mmHg (p < 0.001). The qualified and complete success rate was 50% and 25%, respectively. With the AGV, the IOP reduced from 29 ± 7 mmHg to 16 ± 7 mmHg (p = 0.001). The matched AGV group compared to the Baerveldt-XEN, presented a higher complete success rate (58.3%) and a qualified success rate of 33.3% (p = 0.72). No sight-threatening complications were recorded in both groups.

CONCLUSIONS

The Baerveldt-XEN disclosed a low complete success rate at 1 year of follow-up, although with no major safety concerns. While studies with a longer follow-up are needed to demonstrate the potential advantages and disadvantages of the Baerveldt-XEN, this technique may be less likely to achieve drop-free efficacy when compared to other flow-restrictor strategies.

Minimally Invasive Surgery, Implantable Sensors, and Personalized Therapies

Glaucoma management has changed dramatically over the last decades, through clinical advances and technological revolutions. This review discusses the latest innovations and challenges faced in the field around three major axes: minimally-invasive glaucoma surgery (MIGS), implantable sensors and injectable therapeutics. Indeed, the vast number of recently developed MIGS techniques has not only provided clinicians with a wide range of therapeutic options, but they have also enabled them to adjust their therapies more finely which may have contributed a more patient-centric decision-making process. Yet, despite considerable advances in the field, the wide heterogeneity in clinical trial designs blurs the surgical outcomes, specificities and indications. Thus, more high-quality data are required to make the choice of a specific MIGS procedure more than an educated guess. Beyond the scope of MIGS, the potential of IOP telemetry for self-assessment of IOP-control through implantable sensors is developing into a real option for clinicians and an empowering opportunity for patients. Indeed, providing patients with direct feedback enables them to take control and have a clearer representation of their care, in turn leading to a better control of the disease. However, there are potential issues with self-monitoring of IOP, such as increased anxiety levels induced by measured IOP fluctuations and peaks, leading to patients self-treating during IOP spikes and additional office visits. Furthermore, the advent of implantable therapeutics may soon provide yet another step towards personalized glaucoma treatment, by offering not only an efficient alternative to current treatments, but also a therapeutic option that may better adapt to patients' lifestyle. After several decades of relative stagnation through the last century, glaucoma has now entered what many view as a golden age for the specialty. Like every revolution, this one brings its fair share of uncertainty, clinical questioning and uneasy periods of adaptation to ever-changing expectations. Yet, while it is impossible to guess what the landscape of glaucoma surgery will be like in ten or fifteen years, data suggest a bright outlook both for patients and clinicians.

Xen Gel Stent as a minimally invasive option for intraocular pressure control after DSAEK: A case study

PURPOSE

This case study describes the implantation of a Xen45 Gel Stent in a patient that had previously undergone Descemet stripping automated endothelial keratoplasty (DSAEK). Glaucoma might worsen after corneal transplant, and while medical treatment is the first-line therapy to achieve intraocular pressure (IOP) control, a surgical approach is required when medication does not reach the target IOP.

METHODS

In 2017, the patient underwent treatment in both eyes with ocular hypotensive eye drops for pseudoexfoliative (PXF) glaucoma. In May 2017, DSAEK was performed on the right eye because of the presence of a pseudophakic bullous keratopathy. An increase in IOP, resistant to medical treatment, was observed after the corneal transplant. In November 2017, a Xen45 Gel Stent was implanted.

RESULTS

The patient had a positive outcome with a Xen45 Gel Stent implant in surgical glaucoma treatment after DSAEK. The case demonstrated excellent postoperative IOP control, stable vision and a healthy ocular graft at short-term and long-term follow-ups.

CONCLUSION

Studies with larger numbers of patients in this particular form of therapy are required. Nevertheless, Xen45 Gel Stent implantation appears to be a promising option in preventing or limiting glaucoma in patients who have previously undergone DSAEK. It is a brief, minimally invasive procedure with reduced postoperative inflammation, faster visual recovery and a lower risk of graft damage or hypotony, even in the case of PXF glaucoma.

Impact of Phacoemulsification Combined with XEN Gel Stent Implantation on Corneal Endothelial Cell Density: 2-Year Results

INTRODUCTION

Corneal integrity has long been a preoccupation of glaucoma surgeons considering glaucoma drainage device surgery or antimetabolite-enhanced trabeculectomy. Despite having demonstrated a good safety profile and significant intraocular pressure-lowering capacities, the impact of XEN gel stents on endothelial density was never specifically investigated. The purpose of this study is to assess the effect of XEN gel stents on central endothelial cell density (ECD) over 24 months. To achieve this, we compared the effect on ECD of combined XEN surgery with that of a standard phacoemulsification procedure.

METHODS

This was an investigator-initiated, retrospective study, conducted at a single tertiary glaucoma center. Patients with primary or secondary open-angle glaucoma who underwent XEN implantation combined with phacoemulsification between January 2015 and June 2016 were retrospectively enrolled. Patients who had undergone standalone phacoemulsification over the same period of time were enrolled to form the control group of this comparative study. The primary outcome measure was the ECD. Patients who had undergone standalone XEN implantation and patients for whom both a baseline and 24-month ECD could not be obtained were excluded from the analysis. Percentages of ECD reductions were calculated for each studied eye, and the mean of ECD reductions was calculated for each group as well as for subgroups.

RESULTS

Thirty-two eyes of 23 patients (mean age=76.0±7.9 y, 60% female) underwent standalone phacoemulsification (n=15) or combined XEN surgery (n=17) and had an ECD both at baseline and 24-month postoperatively. Mean baseline ECDs were 2568±491 versus 2379±335 cells/mm, respectively (P=0.21). In the combined XEN surgery group, 58.8% of eyes (n=10) required at least 1 mitomycin C (MMC)-enhanced needling revision to maintain their target intraocular pressure. In the standalone phacoemulsification group, ECD decreased by a mean 14.5%, from 2567.7±491.2 to 2196.1±591.9 cell/mm (P=0.072). In the combined XEN surgery group, ECD decreased by a mean 14.3%, from 2378.8±334.7 to 2039.6±451.1 cell/mm (P=0.018). The difference in percentage reduction of ECD between the 2 groups was not statistically significant (P=0.226). Within the combined XEN surgery group, the ECD decreased by a mean of 15.4% in patients who did not undergo needling revisions and by 13.1% in patients who underwent the MMC-augmented procedure (P=0.485). In the 3 patients who underwent >1 needling revision, a 21.3% reduction in ECD was observed, but the difference was not statistically significant (P=0.653). Neither the time of the first needling (P=0.452), the patients' age (P=0.285), or sex (P=0.308) was statistically associated with ECD loss.

DISCUSSION

The present study demonstrated that the XEN gel implant combined with phacoemulsification produces 24-month ECD loss of a similar magnitude to that observed following standalone phacoemulsification. MMC-augmented needling revisions do not appear to have an impact on ECD.

Lamellar sclerectomy augmented XEN gel stent glaucoma surgery

PURPOSE

To describe a surgical technique to optimize XEN gel stent position and its outflow.

METHODS

A small 1- to 1.5-mm square lamellar sclerectomy was created at the external tip of the XEN gel stent implant. The lamellar scleral tissue, served as a patch graft, was secured at the gel stent insertion site.

RESULTS

Four sequential, unselected, patients with failed primary XEN gel stent surgeries underwent bleb revisions with the technique described. These four patients achieved unmedicated intraocular pressures between 10 and 12 mmHg and a favourable bleb morphology despite repeated mitomycin C applications at 6 months.

CONCLUSION

Lamellar sclerectomy with auto-scleral graft augmented XEN gel stent surgery deliver successful short-term outcomes without major complications observed.

XEN-augmented Baerveldt drainage device implantation in refractory glaucoma: 1-year outcomes

PURPOSE

To evaluate outcomes of XEN-augmented Baerveldt drainage device implantation in refractory glaucoma and factors predicting surgical success.

METHOD

All eyes undergoing XEN-augmented Baerveldt for refractory open-angle glaucoma at a tertiary glaucoma centre between January 2016 and November 2017 were retrospectively enrolled. Intraocular pressure (IOP), number of anti-glaucomatous medications and postoperative adverse events (AEs) were analysed for 1 year postoperatively. Surgical success was defined as achieving (1) an IOP ≤ 15 mmHg or (2) ≤ 18 mmHg, with or without (qualified) or without medications (complete). Any subsequent glaucoma surgery was considered failure.

RESULTS

Out of 60 eyes enrolled, 12-month data were available for 41 eyes (71.4%). Mean age was 64.7 ± 23.1 years (50% female). Following surgery, IOP decreased significantly from a baseline of 29.9 ± 13.2 to 15.2 ± 6.6 mmHg (- 49.2%; P < 0.0001) at 12 months. Anti-glaucoma medications decreased from 3.0 ± 1.3 to 1.3 ± 0.9. Complete success was achieved by 14.6% of eyes using both the ≤ 15 mmHg and the ≤ 18 mmHg thresholds, and qualified success was achieved in 43.9% and 48.8%, respectively. Throughout the follow-up period, AEs were observed in 51.2% (hypotony = 24.4%; XEN blockage = 17.1%; displacement of XEN gel stent = 4.9%; hyphema = 4.9%). The 12-month success rate was significantly higher in patients who presented an IOP ≤ 10 mmHg at 1 week (58.6%, P = 0.001). Overall, 41.5% of patients required reoperation at 12 months (58.8% revision of the surgery; 41.2% transscleral cyclodestruction).

CONCLUSION

XEN-augmented Baerveldt is a safe and moderately effective technique to reduce IOP and anti-glaucoma medications in refractory glaucoma. IOP at 1 week seems to be a predictor for surgical success. Nevertheless, a high proportion of patients requires reoperation.

Minimally Invasive Glaucoma Surgery: Where Is the Evidence?

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.

Real-World Retrospective Consecutive Study of Ab Interno XEN 45 Gel Stent Implant with Mitomycin C in Black and Afro-Latino Patients with Glaucoma: 40% Required Secondary Glaucoma Surgery at 1 Year

PURPOSE:

The aim of this study was to determine the postoperative course after the ab interno XEN45 Gel Stent implantation in Black and Afro-Latino, patients with glaucoma.

METHODS:

This was a single-center, retrospective study. All patients with glaucoma who underwent ab interno XEN implantation were included in the study. All of the patients were Black and Afro-Latino making up the demographics of the local community. Investigated parameters were intraocular pressure (IOP), the number of medications, visual acuity, IOP-follow-up, intraoperative and postoperative complications, and additionally performed surgeries.

RESULTS:

Of 20 eyes that had undergone the procedure with 1-year follow-up, eight failed before 12 months requiring additional glaucoma surgery. Of the 12 that were successful at 1 year, 9 (75%) eyes underwent XEN + cataract surgery and 3 (25%) had XEN surgery alone. Of the eyes that completed 12-month follow-up, the mean medicated IOP was 15.3 ± 6.2 mmHg at baseline, and 12.9 ± 4.5 mmHg at 12 months, a 16% IOP reduction. Mean medications dropped from 3.58 ± 0.7 preoperatively to 1.75 ± 1.5 at 12 months.

CONCLUSIONS:

The ab interno XEN gel implant as a standalone procedure or combined with cataract surgery demonstrated a safe and sustained IOP reduction for only 60% of patients after 12 months. In Black and Afro-Latino patients receiving the ab interno XEN implant, 40% of patients needed additional surgery within 12 months.

Intra-Scleral Ciliary Sulcus Suprachoroidal Microtube: Making Supraciliary Glaucoma Surgery Affordable

PURPOSE

The suprachoroidal space (SCS) has been a successful target to lower intraocular pressure (IOP) in glaucoma patients. We present the results of 4 patients who underwent a novel glaucoma surgical procedure to lower IOP: Intrascleral Ciliary Sulcus-Suprachoroidal Microtube.

METHODS

A sterile medical grade silicone microtube (Tube extender, New World Medical) was surgically placed to drain aqueous from the posterior chamber ciliary sulcus of the eye to the SCS. The internal diameter of the tube was 300 um and the length varied from 8-10mm. After informed consent was obtained and witnessed, this procedure was performed in glaucoma patients with pseudophakia. The tube was placed intrasclerally beneath an inferotemporal sclera flap (50% thickness approximately 4mm x 4mm). The anterior end of the tube was inserted into the ciliary sulcus approximately 2mm from the limbus and the posterior end was placed into the SCS approximately 4mm from the limbus. The microtube was sutured to the sclera with a 10-0 nylon suture. 8-0 vicryl sutures were used to close the sclera flap and the conjunctiva inferotemporally.

RESULTS

All 4 patients had lower IOP. The average reduction of IOP was 36% at 3 months. The amount of glaucoma medications per patient at 3 months dropped from an average of 3 to 0.25. The risks are similar to traditional glaucoma incisional surgery.

CONCLUSION

This new technique of Intrascleral Ciliary Sulcus-Suprachoroidal Microtube in all four patients with mild, moderate, and advanced glaucoma demonstrated a significant lowering of IOP and a decrease in the number of medications. Further research is required to assess long term efficacy and safety.

Delayed Obstruction of XEN Gel Stent by Cell Debris in Primary Open-angle Glaucoma: A New Insight into the Pathophysiology of Filtration Device Failure

Aim

The aim of this report is to explore the risk factors of XEN stent obstruction, suggesting the need for a stricter control of these factors and highlighting areas for further research.

Background

Despite its proven effectiveness and safety profile, XEN gel stents (Allergan Plc, Dublin, Ireland) can become obstructed. The causes and predicting factors for such obstructions still require further research. While hyphema has long been known to be responsible for secondary glaucoma through trabecular obstruction, it has not been associated, to date, with XEN gel stent obstruction.

Case description

We describe the case of a 55-year-old female patient with primary open-angle glaucoma (POAG) who underwent bilateral XEN gel surgery. Her left eye developed a 2 mm postoperative hyphema, which resolved spontaneously within 8 days. Intraocular pressure (IOP) normalized at 12 mm Hg and increased to 50 mm Hg after 1 month in an otherwise normal-looking eye. Intraoperative examination revealed a nonfunctioning XEN gel stent, which was replaced and sent for laboratory analysis. Macroscopic examination of the tube confirmed obstruction with cellular debris. Tube replacement restored good filtration.

Conclusion

This case report confirms cellular debris as a potential cause of XEN gel stent occlusion, suggesting that aqueous red blood cells (RBCs) could potentially pose a threat to the microstents’ patency even in cases when the bleeding was minimal and self-limited and where the IOP was still controlled at the time of full hyphema resolution. This observation could lead to recommendations for a stricter control of bleeding risk factors prior to microinvasive glaucoma surgery (MIGS), and it raises the question of whether anterior chamber (AC) washout should be advised in postoperative hyphema.

Clinical significance

This case highlights some previously unreported risk factors for XEN stent obstruction and suggests that stricter control of bleeding and monitoring of patients following hyphema could improve surgical outcome.

How to cite this article

Gillmann K, Bravetti GE, Mansouri K. Delayed Obstruction of XEN Gel Stent by Cell Debris in Primary Open-angle Glaucoma: A New Insight into the Pathophysiology of Filtration Device Failure. J Curr Glaucoma Pract 2019;13(3):113–115.