Laser Iridoplasty to Treat Iris-occluded XEN Gel 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.

Iris Obstruction Following PRESERFLO™ Microshunt Implantation and Surgical Management

PURPOSE

To present a case of lumen obstruction after implantation of microshunt with subconjunctival drainage and subsequent management.

CASE REPORT

A 56-year-old male with primary open angle glaucoma underwent uneventful PRESERFLO™ MicroShunt implantation in both eyes. Five months after surgery the patient presented with an intraocular pressure of 26▒mmHg in the right eye due to iris obstruction.

RESULTS

The iris fibers were severed and removed surgically to free the lumen. Follow-up showed a normalised intraocular pressure of 10▒mmHg and a free lumen.

CONCLUSION

Uncontrolled intraocular pressure due to iris obstruction following PRESERFLO™ Microshunt was addressed by surgical removal of iris fibers at the lumen entrance without the need for tube repositioning.

Appositional Choroidal Detachment Following XEN45 Gel Stent Requiring Surgical Drainage

An 82-year-old man with severe primary open-angle glaucoma on maximal medical therapy underwent an ab externo closed conjunctival Xen45 device insertion with mitomycin C. The surgery was uncomplicated, with a first postoperative day intraocular pressure of 4 mm Hg and visual acuity of 20/40 OD. Ten days later, the patient presented with an intraocular pressure of 5 mm Hg and a visual acuity of counting fingers at 5 feet. Examination showed Seidel negative bleb, shallow anterior chamber, and large nonappositional choroidal detachments. Medical therapy with steroids and cycloplegia was initiated. One week later, the serous choroidal detachments became appositional, and Xen explantation and surgical drainage of the choroidal detachment was performed. Postoperatively, the vision improved to 20/60. Significant choroidal detachments can occur after XEN45 implantation requiring surgical intervention.

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.

Recanalization of XEN-45 gel stent occlusion with cortical material after phaco-XEN surgery using Nd: YAG laser treatment: A case report

INTRODUCTION

The XEN Gel Stent (Allergan Inc., CA, USA) has been widely used in minimally invasive glaucoma surgery to lower intraocular pressure considering reasonable efficacy and safety profiles. However, the XEN gel stent could be occluded by fibrin, blood clots, or the iris due to its small lumen design for preventing postoperative hypotony. To date, only a few studies have assessed XEN occlusion after combined phacoemulsification with XEN gel implantation and how to manage this condition. We describe the first case report of XEN gel stent obstruction by cortical material, demonstrated by anterior segment optical coherence tomography (AS-OCT), which resolved effectively after low-energy neodymium-doped yttrium aluminum garnet (Nd: YAG) laser shock wave treatment.

PATIENT INFORMATION

A 76-year-old Korean male patient underwent uncomplicated phaco-XEN-gel stent implantation and presented with low intraocular pressure (IOP) with a well-functioning filtering bleb during the first postoperative 4 days. On postoperative day 5, the XEN lumen was occluded by the cortical material, with an intraocular pressure elevation of 28 mm Hg. Slit-lamp examination revealed that cortical material was causing a block into the internal ostium of the XEN gel implant. AS-OCT examination also demonstrated the presence of hyper-reflective materials at the intraluminal portion and peritubular portion around the internal ostium of the XEN gel implant.

DIAGNOSIS

XEN gel stent occlusion with cortical material after Phaco-XEN surgery.

INTERVENTIONS

Low-energy Nd: YAG laser shock wave treatment.

OUTCOMES

The IOP dropped from 28 mm Hg to 8 mm Hg immediately after treatment. Transient hypotony and a slightly shallow anterior chamber were noted over the 3 days after YAG laser treatment. The IOP continued to be well-controlled until 3 months later (range; 6 - 12 mm Hg).

CONCLUSIONS

To the best of our knowledge, this is the first case report on the efficacy of Nd: YAG laser treatment for recanalization of XEN implant occluded by the cortex. Moreover, AS-OCT could provide additional clinical information for recanalization of the XEN gel stent.

Combined argon laser peripheral iridoplasty and Nd: YAG laser shock wave therapy for recurrent XEN gel stent obstruction due to iris incarceration: A case report

INTRODUCTION

Despite its proven effectiveness and safety profile, the XEN Gel Stent (Allergan Inc., CA, USA) has a small lumen and is therefore likely to become occluded by fibrin, a blood clot, or even the iris. However, few studies have investigated XEN-iris occlusion and how to manage this condition. We describe the first case report of recurrent XEN gel stent obstruction by iris incarceration, which was resolved following a combined treatment with argon laser peripheral iridoplasty (ALPI) and low-energy neodymium-doped yttrium aluminum garnet (Nd: YAG) laser shock wave treatment.

PATIENT INFORMATION

A 74-year-old Korean male underwent uncomplicated XEN gel stent implantation and presented with low intraocular pressure (IOP) with a well-functioning filtering bleb during the first postoperative week. On postoperative day 10, the XEN lumen was occluded by the iris and demonstrated an IOP spike of 33 mmHg. Despite the use of pilocarpine, the iris incarceration persisted. Therefore, surgery to reposition the XEN stent was attempted using a gonio-prism and intraocular forceps. After the first revision surgery, the IOP and stent position were stable for 2 weeks. However, recurrent partial obstruction of the stent by the iris, pigment dispersion into the intraluminal space, and an elevated IOP of 24 mmHg were observed later.

DIAGNOSIS

Recurrent XEN gel stent occlusion by the iris and intraluminal pigment dispersion.

INTERVENTIONS

Combined ALPI and low energy Nd: YAG laser shock wave therapy.

OUTCOMES

IOP dropped from 24 mmHg to 10 mmHg immediately and continued to be well-controlled until 3 months later (range: 8-12 mmHg).

CONCLUSIONS

To the best of our knowledge, this is the first case report of the efficacy of combined laser treatment for relieving recurrent XEN implant occlusion by the iris. This combination laser treatment might be a relatively safe rescue treatment to restore the patency of a XEN gel stent occluded by the iris, even in cases with recurrent XEN stent obstruction after surgical repositioning.

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.

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.