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.

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.

No Changes in Keratometry Readings and Anterior Chamber Depth after XEN Gel Implantation in Patients with Glaucoma

Background: This study aimed to compare keratometry and anterior chamber depth (ACD) changes after XEN implantation in primary open-angle glaucoma (POAG) cases over a 3-month follow-up period. Methods: Twenty patients with POAG who underwent XEN63 implantation, either standalone or combined with cataract surgery, were included. Preoperative data, including best-corrected visual acuity (BCVA), refraction, gonioscopy, ophthalmoscopy, intraocular pressure (IOP) evaluation, and axial length, were collected. Corneal topography and ACD measurements were assessed preoperatively and at postoperative days 1, 7, 15, 30, 60, and 90. Each patient's eye that underwent XEN surgery was included in the study group, with the fellow eye serving as a control. Results: In the study group, there was a significant decrease in IOP after XEN stent implantation at all investigated time intervals (p < 0.05). However, changes in mean ACD did not show statistically significant differences at any follow-up examination in both the study and control groups. Additionally, keratometry readings revealed no significant changes in total astigmatism or steep keratometry values in either group. Conclusions: XEN implantation in POAG cases resulted in a significant decrease in IOP over the 3-month follow-up period. However, there were no significant changes observed in mean ACD or keratometry readings, indicating stability in these parameters post-XEN implantation. These findings suggest that XEN implantation may be an effective option for IOP reduction without affecting corneal curvature or ACD in POAG patients.

Combined versus standalone XEN45 Gel Stent implantation in either phakic or pseudophakic patients: a case-matched study

PURPOSE

To determine differing outcomes among either phakic or pseudophakic patients who received standalone XEN45 Gel Stent (Allergan, an AbbVie Company, CA, USA) implantation and patients who underwent combined surgery with phacoemulsification.

METHODS

This retrospective single-center study involved 180 eyes of 180 participants who underwent XEN45 Gel Stent implantation, of which 60 eyes received combined surgery with phacoemulsification (combined group). Standalone stent implantation was performed on 60 phakic (phakic group) and on 60 pseudophakic eyes (pseudophakic group). The groups were matched in a ratio of 1:1:1 based on multiple criteria. Successful surgery was defined by three scores: IOP at the longest follow-up of < 21 mmHg (Score A) or < 18 mmHg (Score B) and an IOP reduction > 20% or IOP ≤ 15 mmHg and an IOP reduction ≥ 40% (Score C). In all scores, one open conjunctival revision was allowed, and additional repeat surgery was considered a failure.

RESULTS

After an average follow-up time interval of 20.6 ± 12.6 months, there was a mean IOP-reduction by 37% among the entire cohort. Comparative analysis between the three groups did not show significant differences regarding postoperative IOP, postoperative medication score, side effects, revision rate, repeat surgery rate or success rate. A dysfunctional stent was detected in eight eyes (4%) during open conjunctival revision in 76 eyes.

CONCLUSION

The clinical endpoints investigated did not differ significantly among either phakic or pseudophakic patients who received standalone stent implantation and patients who underwent combined surgery. However mean latency between primary stent implantation and first revision surgery after combined surgery was markedly shorter.

Interim Analysis of Clinical Outcomes with Open versus Closed Conjunctival Implantation of the XEN45 Gel Stent

OBJECTIVE

To examine the longitudinal postoperative outcomes of open versus closed conjunctiva implantation of the XEN45 gel stent.

DESIGN

Retrospective multicenter study.

SUBJECTS

One hundred ninety-three patients with glaucoma underwent XEN45 implantation via an open or closed conjunctiva approach.

METHODS

Data on patient demographics; diagnoses; preoperative and postoperative clinical data; outcome measures, including intraocular pressure (IOP); use of glaucoma medications; visual acuity; and complications were collected. Statistical analyses were performed with P < 0.05 as significant.

MAIN OUTCOME MEASURES

Failure was defined as < 20% reduction in IOP from the medicated baseline or a IOP of > 21 mmHg at 2 consecutive visits at postoperative month 1 and beyond, the need for subsequent operative intervention or additional glaucoma surgery, or a catastrophic event, such as loss of light perception. Eyes that had not failed by these criteria and were not on glaucoma medications were considered complete successes. Overall success was defined as those who achieved success either with or without topical medications.

RESULTS

Patients were followed for an average of 17 months. Complete success was achieved in 42.5% and 24.7% of the open and closed groups, respectively (P = 0.01). Overall success was achieved in 64.2% and 37.0% of the open and closed groups, respectively (P < 0.001) at the last follow-up. Bleb needling was performed in 12.4% of eyes in the open group compared with 40% of eyes in the closed group. An IOP spike of ≥ 10 mmHg was twice as likely to occur in the closed group compared with the open group during the postoperative period (40% vs. 18%; P = 0.001).

CONCLUSIONS

Implantation of XEN45 with opening of the conjunctiva resulted in a lower IOP with greater success and lower needling rate compared with those achieved with the closed conjunctiva technique. Similar rates of postoperative complications and vision loss were noted in each group. Although both procedures provide substantial IOP reduction, the open technique appears to result in higher success rates and fewer postoperative interventions.

FINANCIAL DISCLOSURE(S)

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

Results of open bleb revision as management of primary bleb failure following XEN 45 gel stent and Preserflo™ Microshunt

PURPOSE

The success of filtering surgery as in XEN-Gel-Stent (XEN) and Preserflo-Microshunt (PF) depends mainly on a functioning bleb. Primary bleb failure (PBF) is not uncommon and can be treated with needling or open bleb revision (OBR). The aim of the study is to compare surgical outcomes of OBR after XEN and PF.

METHODS

Eyes which received OBR as management of PBF following implantation of XEN or PF were retrospectively included. Intraocular pressure (IOP), number of IOP lowering medications (NoM), and success rates (SR) were compared between groups. Complete and qualified success were defined as IOP ≤18mmHg and a reduction of >20%, without and with medications, respectively.

RESULTS

29 eyes after XEN and 23 eyes after PF were included. Six months following OBR, IOP reduced from 24.2±4.7 to 13.5±4.6 after XEN and from 27.3±8.7 to 15.9±5.8mmHg after PF (both p<0.001). NoM did not change (0.7±1.3 to 0.4±0.8 after XEN and 1.2±1.3 to 1.0±1.5 after PF, p>0.05 for both). Complete SR were higher after XEN than after PF (58.6% vs. 30.4%, p=0.04). Complications were mild and managed mainly conservatively. Additional glaucoma surgery was needed in 17% and 30% of eyes after XEN and PF, respectively (p=0.26).

CONCLUSION

Although OBR was effective as management of PBF following XEN and PF, SR were higher after XEN than after PF along with comparable safety profile. The change of the surgical approach from ab interno during XEN-Implantation to ab externo during OBR seems to enhance SR compared to PF, where both interventions are done ab externo.

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.

Efficacy and Safety Outcomes of XEN Implantation and Gonioscopy-assisted Transluminal Trabeculotomy for the Management of Advanced Open-angle Glaucoma

Aim

Minimally invasive glaucoma surgery (MIGS) is not typically used in patients with advanced-stage glaucoma. This study describes the outcomes and complications of patients with advanced open-angle glaucoma (OAG) who underwent XEN implantation with cataract surgery or gonioscopy-assisted transluminal trabeculotomy (GATT) with cataract surgery.

Methods

This retrospective study identified patients who had undergone XEN implantation or GATT for the management of advanced OAG. Outcomes included surgical success, intraocular pressure (IOP) reduction, number of topical IOP-lowering drops, visual field mean deviation (MD), best-corrected visual acuity (BCVA), and complications. Surgical success was defined as an IOP of <14 mm Hg and a 20% reduction at 12 months without topical IOP-lowering drops (complete success) or with topical IOP-lowering drops (qualified success).

Results

Exactly 70 eyes were enrolled in this study, including 35 who had undergone XEN implantation and 35 who had undergone GATT. The overall surgical success rate was 74.3% (26 of 35) for eyes that underwent XEN implantation and 71.4% (25 of 35) for eyes that underwent GATT. Percent IOP reduction from baseline to 12 months postoperatively was 48% in the XEN cohort and 32% in the GATT cohort. Significant reduction in the use of topical IOP-lowering drops was demonstrated for both XEN (3.26 ± 1.15-1.23 ± 1.28) (p < 0.001) and GATT (2.46 ± 1.12-0.43 ± 0.78) (p < 0.001) cohorts at 12 months postoperatively. The only complication reported was transient hyphema, which occurred in three patients from the XEN group and four from the GATT group, and resolved spontaneously.

Conclusions

Both XEN implantation and GATT may be safe and effective management options when treating patients with advanced OAG. However, larger sample sizes are required to make direct statistical comparisons between these techniques.

Clinical significance

In this study, XEN implantation and GATT combined with cataract surgery were each associated with favorable outcomes in patients with advanced OAG.

How to cite this article

Ruparelia S, Sharif M, Shoham-Hazon N. Efficacy and Safety Outcomes of XEN Implantation and Gonioscopy-assisted Transluminal Trabeculotomy for the Management of Advanced Open-angle Glaucoma. J Curr Glaucoma Pract 2023;17(2):63-67.

Clinical Outcomes of XEN45®-Stent Implantation after Failed Trabeculectomy: A Retrospective Single-Center Study

BACKGROUND

The implantation of a collagen gel micro-stent (XEN45^®) as a minimally invasive form of glaucoma surgery (MIGS) after a failed trabeculectomy (TE) may be an effective option with few risks. This study investigated the clinical outcome of XEN45^® implantation after a failed TE, with follow-up data of up to 30 months.

MATERIALS AND METHODS

In this paper, we present a retrospective review of patients undergoing XEN45^® implantation after a failed TE at the University Eye Hospital Bonn, Germany, from 2012 to 2020.

RESULTS

In total, 14 eyes from 14 patients were included. The mean follow-up time was 20.4 months. The mean time duration between the failed TE and XEN45^® implantation was 110 months. The mean intraocular pressure (IOP) decreased from 17.93 mmHg to 12.08 mmHg after one year. This value increased again to 17.63 mmHg at 24 months and 16.00 mmHg at 30 months. The number of glaucoma medications decreased from 3.2 to 0.71, 2.0, and 2.71 at 12, 24, and 30 months, respectively.

CONCLUSIONS

XEN45^® stent implantation after a failed TE did not lead to an effective long-term decrease in IOP and glaucoma medications in many patients in our cohort. Nevertheless, there were cases without the development of a failure event and complications, and others in whom further, more invasive surgery was delayed. XEN45^® implantation in some failed trabeculectomy cases may, therefore, be a good option, especially in older patients with multiple comorbidities.

Outcomes of 45 μm gelatin stent surgery over 24-month follow-up

BACKGROUND

The main objectives of this study were to determine whether known risk factors for trabeculectomy failure similarly influence gelatin stent outcomes and to identify surgical factors which may optimise success.

METHODS

A retrospective, observational study was conducted at a single centre in Perth, Western Australia over 24 months. Two-hundred and sixty-two eyes of 207 patients underwent XEN-45 stent surgery with various forms of glaucoma. Surgical and postoperative data on subjects undergoing XEN-45 stent surgery was collated. Intraocular pressure (IOP) reduction success was determined using three criteria: 1; IOP <18 mm Hg, 2: IOP <15 mm Hg and 3: >25% IOP reduction from baseline. Kaplan-Meier, mixed effects Cox Proportional hazard model and Chi-Square test were used to measure survival of functioning stents.

RESULTS

The success rates at a maximum of 2 years after surgery by criteria 1, 2 and 3 were 61.3%, 26.2% and 28.9% in primary open angle glaucoma (n = 243), 18.8%, 16.9%, 21.4% in angle closure glaucoma (n = 11), 0%, 0%, 66.7% in congenital glaucoma (n = 5) and 0% in uveitic glaucoma (n = 3). No significant reduction in success was found in those eyes that had prior ocular surgery (all p > 0.07).

CONCLUSIONS

Prior cataract or trabeculectomy surgery does not appear to adversely affect gelatin stent outcomes over 2 years follow up. Gelatin stent surgery appears to have less IOP reduction effect compared to trabeculectomy at 2 years.

Clinical Outcomes of Ab Interno Placement versus Ab Externo Placement of XEN45 Gel Stents

PURPOSE

To compare the effectiveness of ab interno versus ab externo placement of XEN45 gel stents in patients with open-angle glaucoma.

DESIGN

Single-center, noncontrolled, retrospective, comparative case series.

PARTICIPANTS

Eighty-nine eyes of 89 patients with open-angle glaucoma who underwent XEN45 gel stent implantation.

METHODS

Patients underwent either ab interno (group 1) or ab externo (group 2) placement of a XEN45 stent between 2017 and 2020 by a single surgeon. Outcomes were recorded at each follow-up visit from postoperative day 1 up to 24 months, with median follow-up lengths of 12 months and 8 months for groups 1 and 2, respectively.

MAIN OUTCOME MEASURES

The primary outcome measure was the surgical success rate at 8 months. Secondary measures were postoperative intraocular pressure (IOP) and medication usage, complication rates, and bleb revision rates.

RESULTS

Success rates at 8 months were 72% in group 1 (n = 29) and 74% in group 2 (n = 60). There was no difference in the median time to failure between groups (P = 0.98). The mean baseline IOPs were 22.8 ± 7.5 on 3.8 ± 0.9 medications in group 1 and 25.3 ± 10.7 on 3.7 ± 1 medications in group 2. At the last follow-up among eyes with surgical success, the mean IOPs were 12.5 ± 3.8 on 2.2 ± 1.4 medications in group 1 and 12.2 ± 2.1 on 1.8 ± 1.3 medications in group 2. The adjusted mean IOPs and numbers of medications used were significantly lower after XEN45 stent implantation at all postoperative time points compared with baseline in both groups (P < 0.05). There were no significant differences in postoperative adjusted mean IOPs or medications used between the groups at any of the follow-up time points. Complication rates and bleb revision rates were comparable between both groups (P > 0.05).

CONCLUSIONS

The ab externo approach of XEN45 stent placement demonstrates comparable effectiveness to the ab interno approach in patients with open-angle glaucoma, although this study was underpowered to detect a difference in success rates between groups.

Refractive Changes after Glaucoma Surgery-A Comparison between Trabeculectomy and XEN Microstent Implantation

Best-corrected visual acuity often decreases temporarily or permanently after trabeculectomy (TE). The purpose of this study was to compare visual acuity and refractive changes after TE or XEN microstent implantation (XEN) in primary open-angle glaucoma (POAG) or pseudoexfoliation glaucoma (PEX) cases naïve to prior glaucoma surgery over a 24-month follow-up period. We analyzed 149 consecutive glaucoma patients who received either TE or XEN because of medically uncontrollable POAG or PEX. Intraocular pressure (IOP), IOP-lowering medication use, subjective and objective refraction and best-corrected visual acuity were evaluated. In addition, surgically induced astigmatism (SIA) was calculated and compared using the vector analysis method described by Jaffe and Clayman. A total of 93 eyes (85 POAG; 8 PEX) were treated with TE and 56 eyes (50 POAG; 6 PEX) with XEN. After 24 months, the mean IOP and number of IOP-lowering medications used decreased significantly after TE (p < 0.01) and XEN (p < 0.01). In the TE group, mean best-corrected visual acuity (BCVA) changed from 0.16 ± 0.26 to 0.23 ± 0.28 logMAR (p < 0.01) after 24 months, while mean BCVA did not change significantly in the XEN group (preoperative: 0.40 ± 0.50 logMAR, postoperative: 0.36 ± 0.49 logMAR; p = 0.28). SIA was almost the same in both groups at the end of the 24-month follow-up period (0.75 ± 0.60 diopters after TE and 0.81 ± 0.56 diopters after XEN; p = 0.57). In addition, there was no significant correlation between SIA and the observed BCVA changes or SIA and IOP reduction 12 or 24 months after TE or XEN. Our results demonstrate that TE and XEN are effective methods for reducing IOP and IOP-lowering medication use. The SIA was nearly similar in both groups. The SIA does not seem responsible for the decreased visual acuity after TE.

A Case of Refractory Open-angle Glaucoma with Failed Baerveldt Glaucoma Implant and Trabeculectomy Treated with Ab Externo XEN Gel Stent Placement

Aim

We report a case of successful intraocular pressure (IOP) management in a patient with refractory primary open-angle glaucoma (POAG) following implantation of XEN gel implant in the same hemisphere as prior failed filtering surgeries [i.e., Baerveldt glaucoma implant (BGI) and trabeculectomy bleb)].

Background

Glaucoma is a major cause of blindness worldwide and is typically associated with elevated IOP and retinal ganglion cell loss. Treatment centers around decreasing IOP with eye drops and surgical interventions. The advent of minimally invasive glaucoma surgeries (MIGS) has expanded therapeutic options for patients who have failed traditional treatments. The XEN gel implant creates a shunt between the anterior chamber and the subconjunctival or sub-tenon's space, allowing for drainage of aqueous humor without significant tissue disruption. Given that the XEN gel implant also results in bleb formation, it is generally recommended to avoid placement in the same quadrant of prior filtering surgeries.

Case description

A 77-year-old man with a 15-year history of severe POAG of OU presents with persistently elevated IOP despite multiple filtering surgeries and maximal eye drop regimen. The patient had a superotemporal BGI in OU and a scarred trabeculectomy bleb superiorly in the right eye (OD). He underwent an open conjunctiva ab externo XEN gel implant placement in the OD in the same hemisphere as previous filtering surgeries. At 12 months postoperatively, the IOP range continues to be maintained within goal without complications.

Conclusion

The XEN gel implant can be successfully placed in the same hemisphere as prior filtering surgeries and can achieve goal IOP without any surgical complications at 12 months postoperatively.

Clinical significance

A XEN gel implant can effectively lower patients' IOP and can be a unique surgical option in refractory cases of POAG with multiple failed filtering surgeries, even when inserted in close proximity to prior filtering surgeries.

How to cite this article

Amoozadeh SA, Yang MC, Lin KY. A Case of Refractory Open-angle Glaucoma with Failed Baerveldt Glaucoma Implant and Trabeculectomy Treated with Ab Externo XEN Gel Stent Placement. J Curr Glaucoma Pract 2022;16(3):192-194.

The efficacy of XEN gel stent implantation in glaucoma: a systematic review and meta-analysis

Background

Xen is a device for minimally invasive glaucoma surgery, and is used to treat POAG, pseudoexfoliative or pigmentary glaucoma, as well as refractory glaucoma. The efficacy of XEN in treating glaucoma remains to be confirmed and clarified. Hence, we conducted a systematic review and meta-analysis to examine the efficacy and associated complication of XEN implantations.

Methods

We conducted a literature search in PubMed, EMBASE, the Cochrane Library of Systematic Reviews, Web of Science, China National Knowledge Infrastructure, WanFang and SinoMed databases to identify studies, published before May 15, 2021, which evaluated XEN in glaucoma, and parameters for measurements included intra-ocular pressure (IOP), number of anti-glaucoma medications (NOAM), and bleb needling rate. We compared the measurements of XEN-only procedure between phaco-XEN and trabeculectomy, and we also did sub-analysis based on time points, glaucoma types, ethnics, etc. Sensitivity analyses and publication bias were conducted for evaluating bias.This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA 2020) reporting guideline.

Results

We identified 78 eligible studies, analysis revealed obvious IOP reduction after XEN stent implantation (SMD: 1.69, 95% CI 1.52 to 1.86, p value < 0.001) and NOAM reduction (SMD: 2.11, 95% CI 1.84 to 2.38, p value < 0.001). Sub-analysis showed no significant difference with respect to time points, ethnicities, and economic status. No significant difference was found between XEN treatment effect on POAG and PEXG eyes and between pseudo-phakic and phakic eyes. Also no significant difference was found between XEN and phaco-XEN surgery in terms of IOP after surgery (SMD: -0.01, 95% CI -0.09 to 0.08, p value 0.894). However, NOAM (after publication bias correction) and bleb needling rate (RR: 1.45, 95% CI 1.06to 1.99, p value 0.019) were lower in phaco-XEN group compared to XEN only group. Compared to trabeculectomy, XEN implantation had similar after-surgery IOP, however bleb needling rate (RR: 2.42, 95% CI 1.33 to 4.43, p value 0.004) was higher.

Conclusion

Our results confirmed that XEN is effective in lowering both IOP and NOAM till 48 months after surgery. It is noteworthy that XEN implantation leads to higher needling rate, compared to phaco-XEN or trabeculectomy. Further research, studying complications of XEN on non-European ethnicities, especially on Asian, are in urgent need before XEN is widely applied.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02502-y.

Compatibility and Durability of the Gel Stent Material

INTRODUCTION

The XEN Gel Stent (AbbVie Pharmaceuticals) is a device made from Gelatin; a well-known material in the medical field that is firm enough to hold its shape and soft enough to conform to tissues and reduce the risk of erosion. The Gel Stent creates a permanent outflow connection between the anterior chamber and subconjunctival space.

AREAS COVERED

Validation testing done on the Gel Stent to evaluate biocompatibility and durability of the material as well as real-world experience are included and discussed in this paper.

EXPERT OPINION

Correlating the results of the preclinical testing, study outcomes available in the published literature, and the surgeons' experiences, the device and materials have shown to have an acceptable biocompatibility and durability profile, with a stable, nondegradable, and permanent implant.

Predictability of success and open conjunctival revision rates in the subsequent eye after XEN45 Gel Stent implantation according to lens status

PURPOSE

To determine the predictability of success and the risk of open conjunctival revision in the subsequent eye after XEN45 Gel Stent implantation according to lens status.

METHODS

This was a retrospective single-centre study involving 132 eyes of 66 participants who had undergone intraocular pressure (IOP)-lowering XEN45 Gel Stent implantation, either as a standalone procedure in phakic and pseudophakic eyes or in combination with phacoemulsification. Successful surgery was defined by three scores: IOP at follow-up < 21 mmHg (score A) or < 18 mmHg (score B) and an IOP reduction > 20% or IOP ≤ 15 mmHg and an IOP reduction ≥ 40% (score C). In all scores, one open conjunctival revision was allowed, and additional repeat surgery was considered a failure. The predictability of success and revision rate depending on the outcome of the first eye were calculated using Bayes' theorem.

RESULTS

IOP-lowering did not differ significantly between the first and second eyes. Success rates of standalone surgery in the second eye after successful surgery in the first eye significantly exceed rates after prior failure. For the combined procedure, the rates did not differ significantly. For score A, we determined a 76.6% chance of success following a prior success and a 57.9% chance, if prior surgery failed. The corresponding probabilities were 75% and 59.1% for score B, while 66.7% and 15.7% for score C, respectively. We calculated a 60% risk for revision surgery in the standalone phakic group. If the first eye was not revised, the risk of revision in the subsequent eye was 20%. The corresponding risks were 72.7% and 5% for the standalone procedure in pseudophakic patients and 38.4% and 41.7% for the combined procedure, respectively.

CONCLUSION

The results of our study offer a tool to predict the outcome of subsequent eye surgeries based on either the outcome in the initial eye and the type of surgery performed, owing to the high predictive potential.

Three-year effectiveness and safety of the XEN gel stent as a solo procedure or in combination with phacoemulsification in open-angle glaucoma: a multicentre study

Purpose

To assess the 3‐year effectiveness and safety of the XEN gel stent implanted ab interno in open‐angle glaucoma (OAG).

Methods

This study was a multicentre, retrospective chart review of consecutive patients with OAG who underwent ab‐interno gel stent placement alone or combined with phacoemulsification between 1 January 2014 and 1 October 2015. Outcome measures included mean changes in intraocular pressure (IOP) and IOP‐lowering medication count from medicated baseline at 1, 2, 3 (primary outcome) and 4 years (if available) postimplantation. Intraoperative complications, adverse events of special interest (AESIs) and secondary surgical interventions (SSIs) were recorded.

Results

The safety and effectiveness populations included 212 eyes (primary and secondary) and 174 eyes (primary), respectively. Mean IOP and medication decreased from 20.7 mmHg and 2.5 at baseline (n = 163 primary/first implanted eyes) to 13.9 mmHg and 1.1 medications (n = 76) at 3 years postimplantation, respectively. Mean changes from baseline in IOP (−5.6, −6.2 and −6.6 mmHg) and IOP‐lowering medication count (−1.8, −1.6 and −1.4) were statistically significant at 1, 2 and 3 years postimplantation, respectively. Results appeared comparable when implantation was performed with (n = 76) or without (n = 98) phacoemulsification. In primary eyes with 4‐year IOP and medication count data (n = 27), mean IOP was 14.0 mmHg on 1.3 medications at 4 years postimplantation. Fifteen (7.1%) eyes had intraoperative complications, 31 (14.6%) experienced 46 postoperative AESIs, and 26 (12.3%) required SSI.

Conclusion

The gel stent effectively lowered IOP and IOP‐lowering medication count over 3 years, with a predictable and acceptable safety profile, when implanted via the traditional ab‐interno technique.

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.

Efficacy and safety of Ab interno XEN gel implant after a failed filtering surgery

Purpose: To evaluate the efficacy and safety of Ab interno XEN gel stent in patients with open angle glaucoma who underwent a previous failed filtering surgery. Methods: A retrospective, observational, multi-centered and descriptive cohort study was conducted from January 2019 to February 2020 on patients with primary open angle glaucoma (POAG) who underwent XEN gel stent implant after a failed filtering surgical procedure. Main parameters evaluated were: changes in IOP measured with Goldmann applanation tonometer, number of anti-glaucomatous eye drops, postoperative complications, and necessity of further surgical procedures. The quantification of quality of life was obtained from the VFQ-25 questionnaire. A descriptive analysis based on pre- post- and intra-operative data was carried out. Results: In all patients included in the study (6 patients for a total of 7 eyes), IOP dropped during the follow up time. We found a mean percentage reduction of -41.5% at 9 months compared to the preoperative data (baseline). IOP lowered from 21.71 ± 4.64 mmHg to 9 ± 3,21 mmHg 1 day after the operation, 11 ± 3.21 at 1 week, 11.42 ± 1.81 mmHg at 1 month, 12.42 ± 3.10 mmHg at 3 months, 13.57 ± 3.45 at 6 months, 12.71 ± 1.79 at 9 months. In 71.4%, the procedure turned out to be complication free and only one case required needling of the bleb in order to achieve optimal intraocular pressure control. A total of 71.4% patients reached a medication free regimen with a percentage of reduction in the mean number of drugs needed of -88.9%. Conclusion: In our experience, XEN gel stent implant performed in Caucasian patients with POAG and a history of failed filtrating surgery, showed to be an effective and safe procedure.

XEN-Augmented Deep Sclerectomy: Step-by-step Description of a Novel Surgical Technique for the Management of Open-angle Glaucoma

AIM AND BACKGROUND

The present case report describes a novel surgical technique combining XEN gel stent implantation and deep sclerectomy: XEN-augmented deep sclerectomy (XEN-DS).

CASE DESCRIPTION

An active 96-year-old Caucasian woman suffering from pseudoexfoliative glaucoma (PEXG) presented with intraocular pressure (IOP) of 24 mm Hg and a double arcuate visual field defect [mean deviation (MD) -9.6 dB] in her only functional eye despite maximal medical therapy. Considering (1) the magnitude of IOP reduction sought, (2) the risk of complications associated with trabeculectomies and glaucoma drainage devices, and (3) the risk of missed appointments due to the patient's personal and social circumstances, it was decided to tailor the surgical treatment to this patient's specific characteristics combining two existing surgical techniques. Following conjunctival dissection, a superficial scleral flap was lifted 2 mm more posteriorly than in conventional DS, and a XEN gel stent was implanted ab externo through the anterior wall of the deep sclerectomy, into the anterior chamber. A mitomycin C-soaked autologous space maintainer was used. No peri- or postoperative complications were observed. Following XEN-DS, her IOP stabilized between 5 mm Hg and 8 mm Hg through 6 months, and her visual field MD improved to -1.5 dB.

DISCUSSION

The present case report is a proof of concept for this novel surgical technique, confirming that XEN-DS has the potential to achieve substantial and persistent IOP reductions in PEXG with a satisfactory safety profile. Clinical studies are warranted to confirm these results.

HOW TO CITE THIS ARTICLE

Niegowski LJ, Gillmann K, Baumgartner JM. XEN-Augmented Deep Sclerectomy: Step-by-step Description of a Novel Surgical Technique for the Management of Open-angle Glaucoma. J Curr Glaucoma Pract 2021;15(3):144-148.

Impact of failed ab-interno trabeculectomy (trabectome) on subsequent XEN45 gel stent implantation in pseudophakic eyes

PURPOSE

To determine the impact of failed ab-interno trabeculectomy on the postoperative outcome of subsequent XEN45 gel stent (Allergan, CA, USA) implantation in pseudophakic eyes.

METHODS

In this retrospective single-center study, we included 60 pseudophakic eyes from 60 participants who underwent XEN45 gel stent implantation. Thirty eyes each underwent primary stent implantation (control group) or had previously undergone a failed ab-interno trabeculectomy (trabectome group). The groups were matched at a 1:1 ratio based on the following criteria: preoperative and maximum Intraocular pressure (IOP), preoperative medication score, cup/disk-ratio, follow-up time, best-corrected visual acuity at baseline, age, and the proportion of patients classified as primary open angle glaucoma or exfoliation glaucoma. We defined a successful surgery by the following three scores: an IOP reduction > 20% and IOP at the longest follow-up < 21 mmHg (Score A) or < 18 mmHg (Score B) or IOP ≤ 15 mmHg and an IOP reduction ≥ 40% (Score C). One open conjunctival revision was allowed in all scores, and a repeat surgery was considered a failure.

RESULTS

Following an average follow-up period of 22 ± 12 months, we observed a mean IOP reduction of 38%, from 23.5 ± 5.2-14.5 ± 5.0 mmHg. Comparative analyses between the groups did not reveal a significant difference in the postoperative IOP, postoperative medication score, side effects, revision rate, repeat surgery rate, or success rate.

CONCLUSIONS

Trabectome is a viable first-line procedure for medically uncontrolled glaucoma before filtering ab-interno microstent surgery is considered.

Needling and open filtering bleb revision after XEN-45 implantation-a retrospective outcome comparison

Purpose

To compare efficacy and safety of needling and open bleb revision after XEN-45 surgery.

Methods

This retrospective study represents real-life data of patients who underwent XEN-45 surgery between November 2014 and June 2018 in the Vienna General Hospital. The following groups were formed for data evaluation: (PSEA) primary surgery secondary intervention allowed (n = 268); (PS) primary surgery until secondary intervention (n = 268); (N) first needling until additional secondary intervention (n = 55); (BR) first bleb revision until additional secondary intervention (n = 105). Main outcome measures were pre- and postoperative intraocular pressure (IOP), number of glaucoma medication (GM), Kaplan–Meier success rates, and secondary intervention rates. Success was defined as postoperative IOP < 21 mmHg and < 18 mmHg together with ≥ 20% IOP reduction with medication allowed.

Results

IOP (and GM) was lowered from 23.5 ± 8.0 (GM 3.1 ± 1.0) to 14.9 ± 8.2 mmHg (1.2 ± 1.4) in group PSEA and 18.1 ± 8.2 mmHg (1.5 ± 1.4) in group PS, in group N from 23.2 ± 10.1 (1.5 ± 1.0) to 19.3 ± 8.5 mmHg (2.2 ± 1.3) and in group BR from 22.0 ± 8.0 mmHg (2.5 ± 1.1) to 15.5 ± 6.4 mmHg (1.3 ± 1.5) after a median follow-up of 16.0, 8.4, 4.8, and 7.3 months, respectively. Success rates at 1 year were significantly higher in group BR (50.7%) compared to PS (37.7%, p = 0.019) and N (24.3%; p = 0.015). An additional intervention was required less frequently in group BR (17.1%) compared to group PS (49.6%, p < 0.001) and group N (54.5%, p < 0.001).

Conclusion

Our data appear to indicate favorable outcomes for open XEN bleb revision in terms of Kaplan–Meier success rates and secondary intervention rate compared to the needling procedure.

Efficacy and safety data for the Ab interno XEN45 gel stent implant at 3 Years: A retrospective analysis

PURPOSE

To report efficacy and safety measures of the XEN45 gel stent at 36 months in the UK National Health Service setting.

METHODS

Retrospective non-comparative audit of the records of patients who underwent XEN45 implantation between June 2015 and May 2017 was performed. Main outcome measures were intraocular pressure and number of antihypertensive medications used. Failure was defined as need for further surgery or stent removal. Success was defined as a 20% decrease in intraocular pressure without the need for additional glaucoma medications or a reduction in antihypertensive medications without an increase in baseline intraocular pressure. Needling rates and preoperative factors effect were assessed.

RESULTS

The cohort included 205 patients (205 eyes) with primary open angle glaucoma (84.4%), angle closure glaucoma (7.8%), or refractory glaucoma (7.8%), 62.9% had a stand-alone procedure and 37.1%, a combined phaco-XEN45 procedure. Mean intraocular pressure was 22.6 ± 7.0 mmHg at baseline compared to 14.7 ± 3.8 mmHg at 24 months and 14.0 ± 2.9 mmHg at 36 months (p < 0.001 for both). Mean number of medications used was 2.6 ± 1.1 at baseline compared to 0.5 ± 0.9 and 0.6 ± 1.0, at 24- and 36-months, respectively (p < 0.001 for both). The failure rate at 36 months was 25%. Needling was required in 36.6%. Evaluation of background factors yielded an increased failure rate in non-Caucasians compared to Caucasians (74% vs 21%, p < 0.001).

CONCLUSION

XEN45 implantation is effective and safe at 36 months' follow-up. Patients should be advised regarding the risk of failure and possible need for bleb revisions. Careful patient selection may be required.

Early Experience with the New XEN63 Implant in Primary Open-Angle Glaucoma Patients: Clinical Outcomes

The new XEN63 implant is a minimally invasive glaucoma surgery device with limited experience in real life. This retrospective study included open-angle glaucoma patients who underwent XEN63 implant, either alone or in combination with cataract surgery. Primary endpoints were the intraocular pressure (IOP) at month 3 and the incidence of serious adverse events. Twenty-three eyes of 23 patients were included. Mean age was 67.8 ± 15.3 years and 15 (65.2%) were women. Mean IOP was significantly lowered from 27.0 ± 7.8 mmHg at baseline to 12.2 ± 3.4 mmHg at month 3 (p < 0.0001). Mean IOP lowering was 40.8 ± 23.5%, with 14 (60.9%) and 16 (69.6%) eyes achieving an IOP lowering ≥30% and ≥20% without hypotensive medication, respectively. The number of hypotensive medications (NHM) was significantly reduced from 2.27 ± 0.94 drugs at baseline to 0.09 ± 0.42 drugs at month 3, p < 0.0001. Four (17.4%) eyes had hypotony (IOP ≤ 6 mmHg) at postoperative day one, which was successfully resolved without sequelae. Four (17.4%) eyes had choroidal detachment (3 at day 7 and 1 at day 15), which was successfully resolved with medical treatment, at the month 1 visit. Three (13.0%) eyes required needling (mean time for needling 35.6 ± 9.7 days). XEN63 significantly lowered IOP and reduced the NHM, with a good short-term safety profile.

Primary Needling of the Ab Interno Gelatin Microstent Reduces Postoperative Needling and Follow-up Requirements

PURPOSE

To evaluate the effect of primary needling at the time of ab interno gelatin microstent insertion on postoperative needling rates.

DESIGN

Retrospective, interventional cohort study.

PARTICIPANTS

Eighty-six eyes of 74 patients with no prior incisional surgery.

METHODS

Consecutive eyes with open-angle glaucoma refractory to medical treatment that underwent ab interno gelatin microstent insertion (XEN; Allergan Inc.) with or without primary needling.

MAIN OUTCOME MEASURES

Primary outcome measure was the proportion of eyes requiring postoperative needling. Secondary outcome measures included the mean reduction in intraocular pressure (IOP), topical glaucoma medication use, complications, reoperations, and number of follow-up clinic visits over 12 months.

RESULTS

Fifty-one eyes (42 patients, median age 74 years) underwent XEN surgery with primary needling at the time of surgery, and 35 eyes (32 patients, median age 73 years) underwent XEN surgery without routine primary needling. Eyes that received routine primary needling had an 84.8% lower rate of postoperative needling (3.9% vs. 25.7%, P = 0.003) and required fewer postoperative clinic visits (P = 0.043). Median IOP was 18.0 mmHg (interquartile range [IQR], 13.0-23.0) on 3.0 (IQR, 2.0-3.0) classes of topical medications at baseline. At 12 months, the median IOP was 11.0 mmHg (IQR, 9.0-14.0) in the primary needling group and 11 mmHg (IQR, 10.0-14.0) when primary needling was not routinely performed. Both groups demonstrated a high safety profile. In total, 5 eyes required further glaucoma surgery with insertion of a glaucoma drainage device.

CONCLUSIONS

Primary needling at the time of XEN gel stent insertion is associated with a significant reduction in the need for postoperative needling and postoperative clinic visits. This modification provides a predictable postoperative course with a significant and sustained reduction in both IOP and glaucoma medication requirements with less intense postoperative management.

Outcome of a single XEN microstent implant for glaucoma patients with different types of glaucoma

BACKGROUND

The aim of this retrospective study was to compare the efficacy and safety profile of a single XEN-microstent in different types of primary and secondary open angle glaucoma.

METHODS

A single XEN microstent was implanted in patients with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG), pseudoexfoliation glaucoma (PEX) and secondary glaucoma (Sec.Gl). The intraocular pressure (IOP), the active substances of the applied IOP-lowering drugs, the best corrected visual acuity (BCVA) and the mean deviation (MD) of the perimetry were measured at baseline and at regular follow-ups, scheduled at 2 days and 1, 3, 6 and 12 months after surgery.

RESULTS

153 eyes were included in this analysis. 113 eyes were affected by POAG (74%), 5 eyes by NTG (3%), 22 eyes by PEX (14%) and 13 eyes by Sec. Gl (9%). Mean IOP decreased in all treatment groups during the 12 months of follow-up (complete group: 23.9 ± 7.4 to 15.4 ± 5.1 mmHg (p < 0.01); POAG: 22.8 ± 6.5 to 15.1 ± 4.6 mmHg (p < 0.01); NTG: 16.6 ± 3.4 to 11.6 ± 2.2 mmHg (p < 0.05); PEX: 28.0 ± 7.9 to 17.1 ± 6.6 mmHg (p < 0.01); Sec.Gl: 28.9 ± 13.9 to 15.5 ± 6.9 mmHg (p < 0.05)). In the 153 eyes the average number of IOP-lowering drugs applied decreased from 2.6 ± 1.2 to 0.8 ± 1.3 12 months after surgery (p < 0.01). BCVA and mean deviation of automated standard perimetry remained stable in all groups during follow-up.

CONCLUSION

As in eyes suffering from POAG, IOP and number of IOP-lowering drugs applied can be effectively reduced by XEN implantation in eyes suffering from NTG, PEX and secondary glaucoma while leaving BCVA and visual field unchanged.

TRIAL REGISTRATION

Trial was registered at DRKS (registration number: DRKS00020800 , Registered 25.February 2020 - Retrospectively registered).

Extraembryonic Endoderm (XEN) Cells Capable of Contributing to Embryonic Chimeras Established from Pig Embryos

Most of our current knowledge regarding early lineage specification and embryo-derived stem cells comes from studies in rodent models. However, key gaps remain in our understanding of these developmental processes from nonrodent species. Here, we report the detailed characterization of pig extraembryonic endoderm (pXEN) cells, which can be reliably and reproducibly generated from primitive endoderm (PrE) of blastocyst. Highly expandable pXEN cells express canonical PrE markers and transcriptionally resemble rodent XENs. The pXEN cells contribute both to extraembryonic tissues including visceral yolk sac as well as embryonic gut when injected into host blastocysts, and generate live offspring when used as a nuclear donor in somatic cell nuclear transfer (SCNT). The pXEN cell lines provide a novel model for studying lineage segregation, as well as a source for genome editing in livestock.

•

Primitive endoderm (PrE) is the predominant lineage emerging from pig blastocyst outgrowths

•

pXEN cells exhibit key features of PrE-progenitors and resemble rodent XEN cells

•

pXEN cells contribute to extraembryonic and embryonic (gut) endoderm in vivo

•

pXEN cells can support full-term development via somatic cell nuclear transfer

Comparison of Clinical Outcomes with Open Versus Closed Conjunctiva Implantation of the XEN45 Gel Stent

Purpose:

To describe the efficacy and safety of open versus closed conjunctival implantation of the XEN45 Gel Stent (Allergan Inc).

Design:

Retrospective, multicenter study.

Participants:

A total of 137 patients with glaucoma who underwent XEN45 implantation via open or closed conjunctival methods. The XEN45 was implanted as a stand-alone procedure or at the time of cataract surgery by 5 surgeons.

Methods:

Patient demographics, diagnoses, preoperative and postoperative clinical data, outcome measures including intraocular pressure (IOP), use of glaucoma medications, visual acuity, and complications were collected. Statistical analyses were performed with P < 0.05 as significant.

Main Outcome Measures:

Failure was defined as less than 20% reduction of IOP from medicated baseline or IOP >21 mmHg at 2 consecutive visits at postoperative month 1 and beyond, the need for subsequent operative intervention or additional glaucoma surgery, or a catastrophic event such as loss of light perception. Eyes that had not failed by these criteria and were not on glaucoma medications were considered complete successes. Eyes that had not failed but required glaucoma medications were defined as qualified successes.

Results:

Complete success was achieved in 31% and 56% of the closed and open groups, respectively (P = 0.01). Qualified success was achieved in 53% and 71% of the closed and open groups, respectively (P = 0.06). At postoperative month 12, the open conjunctiva group was using fewer glaucoma medications than the closed group (0.9 vs. 1.8, respectively; P = 0.02). At postoperative month 12, the open group had a significantly greater percentage of IOP reduction compared with the closed group (43.1% vs. 24.8%, respectively; P = 0.02). Postoperative needling rates were higher in the closed group compared with the open group (36.1% vs. 11.8%, P = 0.001).

Conclusions:

Implantation of the XEN45 with opening of the conjunctiva is a safe and efficacious procedure to lower IOP with comparable success rate and lower needling rate compared with the closed conjunctiva technique. Prospective evaluation of the various methods for XEN45 implantation will allow for further comparison.

[Treatment of secondary glaucoma following intravitreal anti-VEGF therapy with the XEN® gel stent and mitomycin C]

BACKGROUND

Recurrent treatment with intravitreal anti-VEGF (vascular endothelial growth factor) administration can in rare cases lead to secondary glaucoma that is difficult to adjust. The goal of this case series was to analyze the treatment results of the XEN® gel stent in combination with mitomycin C.

METHODS

The long-term follow-up over a period of 18 months was evaluated for 3 eyes in 3 patients that underwent treatment with a XEN® gel stent in combination with mitomycin C as a surgical procedure to reduce intraocular pressure.

RESULTS

The eyes had a baseline pressure of 21-31 mm Hg with 3-5 antiglaucoma medications following 15-25 intravitreal injections. In all 3 eyes a pressure drop of almost 50% to 9-14 mm Hg could be achieved after 18 months with complete discontinuation of all local and systemic medications to reduce intraocular pressure in 2 of the 3 eyes. In 1 eye a choroidal detachment occurred for 2 weeks postoperatively. In another eye a surgical revision of conjunctival penetration was carried out. In two eyes needling was necessary due to scarring. In 2 out of 3 eyes, further intravitreal treatment (9 and 13 respectively) was necessary due to the macular disease but no further increase in intraocular pressure occurred.

CONCLUSION

The XEN® gel stent in combination with mitomycin C is a therapeutic option for difficult to adjust secondary glaucoma following intravitreal anti-VEGF therapy. A continuation of intravitreal anti-VEGF therapy did not lead to a recurrent increase of intraocular pressure.

Conjunctival bleb tearing by XEN gel stent after conjunctival compression sutures

PURPOSE

As minimally invasive glaucoma surgery devices emerge, newer complications are reported. XEN gel stent is safer than classic glaucoma surgery but may also lead to severe adverse effects as hypotony. Compression conjunctival sutures are a useful treatment for overfiltration hypotony after XEN gel stent implantation, but might force bleb tearing by the implant as it gets tightly close to the sutured conjunctiva. This complication has not been previously reported.

METHODS

We report a patient with overfiltration hypotony after XEN gel implantation. Conjunctival compression sutures and implant relocation ab interno were performed obtaining a good outcome. As conjunctiva got tightly close to the stent, the device eroded the bleb so leakage and implant extrusion were found.

RESULTS

Bleb reconstruction by conjunctival autograft was performed in order to avoid hypotony due to continuous conjunctival leakage.

CONCLUSION

Conjunctival compression sutures may be used for overfiltration control after XEN gel implantation but we must be aware of potential conjunctival damage due to implant erosion even if it is correctly positioned. Close follow-up and early suture release may be convenient in these patients.

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.

Cataract and glaucoma combined surgery: XEN® gel stent versus nonpenetrating deep sclerectomy, a pilot study

Background

To compare the efficacy of phacoemulsification (PKE) combined with nonpenetrating deep sclerectomy (NPDS) with mitomycin C (MMC) versus XEN® gel stent with MMC.

Methods

In this nonrandomized, retrospective, comparative, single-center pilot study, 105 consecutive eyes of 75 patients with uncontrolled primary open-angle glaucoma (POAG) and cataract who underwent PKE combined with either XEN implantation (n = 47) or NPDS (n = 58) between May 2013 and November 2018 were included. The primary outcome was complete success at 9 months, which was defined as intraocular pressure (IOP) ≤18, 15 or 12 mmHg without treatment; qualified success was IOP ≤18, 15 or 12 mmHg with antiglaucoma medications. Secondary outcome measures included the number of antiglaucoma medications, visual acuity (VA), and postoperative adverse events.

Results

Using the 18 mmHg threshold, complete or qualified success was achieved in 69.6 and 89.1% in the PKE + XEN group, and 63.8 and 89.7% in the PKE + NPDS group (p = .54 and p = .93), respectively, at 9 months. The mean IOP decreased from 20.8 ± 6.8 mmHg to 16.2 ± 2.8 mmHg in the PKE + XEN group (p < .001, 18.9% mean drop), and from 21.5 ± 8.9 mmHg to 14.9 ± 3.9 mmHg in the PKE + NPDS group (p < .001, 25.6% mean drop). Best-corrected VA significantly improved (p < .001) in both groups. The mean number of antiglaucoma medications was significantly reduced from 2.66 ± 1.1 to 0.49 ± 1.0 in the PKE + XEN group (p < .001) and from 2.93 ± 0.9 to 0.69 ± 1.2 in the PKE + NPDS group (p < .001).

Conclusions

The XEN stent combined with PKE seemed to be as effective and safe as PKE + NPDS at 9 months in this pilot study.

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.

XEN Gel Stent in the management of primary open-angle glaucoma

Purpose

To assess the efficacy and safety of the XEN Gel Stent in patients with primary open-angle glaucoma.

Materials and methods

Twenty eyes of 17 patients (6 males, 11 females) with primary open-angle glaucoma were implanted with XEN Gel Stent. The following data were ascertained in each participant at baseline and at 1, 3, 6, 9 and 12 months following implanting procedure: intraocular pressure, number of anti-glaucoma medications, retinal sensitivity (PS 24/2 w/w), pattern electroretinogram (ISCEV standard), as well as the number of complications.

Results

The mean intraocular pressure reduction in a 1-year follow-up was 18% (21.56 vs. 17.69 mmHg, p < 0.001). The mean number of anti-glaucoma medications was reduced from 3.2 to 1.6 (p = 0.001). The PERG parameters at baseline and at 12 months postoperatively included a stable amplitude of P50 (2.55 µV vs. 2.65 µV, p = 0.024) and N95 (3.45 µV vs. 3.38 µV, p = ns) waves. The delta N95 and delta P50 amplitudes remained stable over the follow-up period (p = ns). The mean deviation (MD) of PS 24/2 was − 6.54 dB vs. − 8.43 dB, p = ns, whereas the pattern standard deviation (PSD) was 6.18 dB vs. 6.91 dB, p = ns. Transient hypotony within the first postoperative week occurred in 18 eyes (90%), whereas hyphema occurred in two eyes (10%). Needle revision of a filtration bleb was performed in five eyes (25%).

Conclusions

The XEN Gel Stent enables significant reduction in intraocular pressure with very low complication rates. It ensures a stabilization of the retinal function as established with the PERG.

Safety and efficacy outcomes of the Xen45 Gel Stent use for refractory glaucoma: a surgery series from surgeon trainees at a tertiary teaching hospital

Background

To study the effect of an ab interno gelatin stent (XEN45 Gel Stent, Allergan Inc., Irvine, California, USA) on intraocular pressure (IOP) as placed by glaucoma fellowship trainees in eyes with refractory glaucoma.

Methods

A prospective noncomparative study at a tertiary training center on 28 unique eyes undergoing ab interno gelatin stent implantation by glaucoma fellowship trainees. Data was collected at baseline and postoperatively at day 1, week 1, and months 1, 3, 5, and 12. Primary outcome was mean IOP change. Secondary outcomes included change in number of glaucoma medication classes and visual acuity. Safety outcomes included needling rates. Surgical success was defined by achieving ≥20% reduction in IOP with the same or fewer classes of antiglaucoma medications from baseline without the need for secondary surgical intervention and/or stent removal.

Results

At baseline, 28.6% (8/28) of the subjects had prior failed incisional glaucoma surgery in a study population that was 54% African-American, with 78% with severe glaucoma (average mean deviation of − 14.58 dB). Thirteen subjects terminated their clinic visits before their 12-month postoperative visit, leaving 15 subjects for end point analysis. Average IOP went from 21.6 mmHg (range 12.0–31.0, SD 6.6) at baseline to 12.5 mmHg (range 7.0–19.0, SD 3.6), a 42.1% reduction (p < 0.007). All subjects decreased the number of medication classes they were taking with an average reduction of 3.8 (range 2–5, SD 0.9) to 1.3 (range 0–3, SD 1.0) classes, or a 65.8% decrease (p < 0.006). Crude surgical success was 80.0% for the 15 subjects that followed up at 12 months. The Kaplan-Meier cumulative probability of success for all 28 subjects at 12 months was 70.4% (95% CI: 44.7–85.8%). Regardless of the length of follow-up, 21.4% (6/28) met failure criteria: 3 subjects failed because they required secondary surgical intervention, and the other 3 did not have adequate IOP reduction. Initial bleb needling rate was 28.6% (8/28) and repeat was 17.9% (5/28).

Conclusions

Compared to the reported literature with experienced ocular surgeons, ab interno gel stent placements by glaucoma fellowship trainees have similar mean IOP, topical medication reduction, surgical success, and needling rates at 12-month follow-up.

XEN gel implant versus gonioscopy-assisted transluminal trabeculotomy for the treatment of open-angle glaucoma

OBJECTIVES

To compare successes and complications of XEN GEL Stent implantation and gonioscopy-assisted transluminal trabeculotomy (GATT) surgery in patients with open-angle glaucoma (OAG).

METHODS

The multicentre, non-randomized, comparative, interventional, retrospective chart review study included 114 eyes undergoing XEN implantation and 107 eyes undergoing GATT for treatment of OAG. A comprehensive ophthalmic examination consisting of best-corrected LogMAR visual acuity (BCVA), Goldmann Applanation Tonometry, biomicroscopy, fundoscopy and gonioscopy was performed, and then, clinical findings, complications and number of antiglaucomatous medications were noted at the 3-, 6-, 12-, 18- and 24-month postoperative visits. Surgical success was defined as IOP ≤ 21 mmHg and 20% ≥ IOP reduction from baseline with (qualified success) or without (complete success) further medication, and without any further IOP-lowering surgery.

RESULTS

The mean ages were 65.8 ± 10.6 and 59.1 ± 14.3 in XEN and GATT groups, respectively (p = 0.001). In XEN group, the percentage of IOP reduction and need of medication were significantly more improved than those in GATT group. The complete surgical success rates were 34.2% and 50.5% in XEN and GATT groups, respectively (p = 0.039), with a success rate of 41.1% in total. Qualified surgical success rates were 97.4% and 89.7% in XEN and GATT groups, respectively (p = 0.025), with a success rate of 93.7% in total. Transient hyphema, the most observed postoperative complication in both groups, cleared in a few days.

CONCLUSIONS

Both MIGS have good efficacy and safety outcomes in lowering IOP and need of medication in patients with OAG. XEN Gel Stent implantation may be preferred in patients with lower IOP values targeted.

Comparison of Ab Interno XEN Gelatin Stent vs Trabeculectomy with Mitomycin C: A Retrospective Study

Aim

To compare outcomes of ab interno XEN gelatin stent (Allergan, Dublin, Ireland) implantation vs trabeculectomy with mitomycin C (MMC).

Materials and methods

A retrospective review was conducted of eyes that underwent standalone XEN implantation or trabeculectomy with MMC at a single institution from 2014 to 2019. Intraocular pressure (IOP), visual acuity, glaucoma medications, complications, and postoperative interventions were evaluated. The primary endpoint was the reduction in IOP at 6 months postoperatively. Secondary endpoints included the incidence of postoperative intervention and complications.

Results

One hundred and seventy-nine eyes were included who underwent XEN (n = 90) or trabeculectomy (n = 89). The mean age was 74.5 ± 7.6 and 68.1 ± 8.2 years old for the XEN and trab groups, respectively (p < 0.001). Baseline IOP for XEN was 17.8 ± 6.0 vs 20.4 ± 9.0 mm Hg for the trab group (p = 0.03). At 6 months, mean IOP for XEN group was 13.5 ± 5.9 mm Hg, representing a 24.1% IOP reduction from baseline (p < 0.001) while mean for trab group was 10.8 ± 4.8 representing a 47% IOP reduction from baseline (p < 0.001). The mean IOP was 2.7 mm Hg lower in trab compared to the XEN group at 6 months (p < 0.003). The number of medications was reduced in both groups from 2.9 ± 1.1 and 3.1 ± 0.9 to 1.1 ± 2.3 and 0.8 ± 1.4 by 6 months postoperatively for XEN and trab groups, respectively (p < 0.001). Complication rates were low for both groups. The needling rate was 30% in XEN vs 7.9% in the trab group (p < 0.001), and 46.1% of eyes in the trab group underwent laser suture lysis. Additionally, IOP reduction and complication rates were similar following XEN in eyes receiving <40 or ≥40 μg of MMC.

Conclusion

XEN implantation produces a substantial reduction in IOP with a favorable safety profile comparable to trabeculectomy. Careful postoperative bleb management is critical to obtain optimum outcomes, and higher MMC doses appear safe and may reduce needling rates.

Clinical significance

This study confirms the safety and efficacy of XEN gelatin stent implantation in comparison to trabeculectomy with MMC.

How to cite this article

Sharpe R, Pham G, Chang P. Comparison of Ab Interno XEN Gelatin Stent vs Trabeculectomy with Mitomycin C: A Retrospective Study. J Curr Glaucoma Pract 2020;14(3):87–92.

XEN® stent complications: a case series

Background

XEN® gel stent (Allergan, Dublin/Republic of Ireland) is a relatively new microinvasive glaucoma device providing an ab-interno approach to the subconjunctival space for aqueous drainage and reduction of intraocular pressure. It is thought to be less invasive, reduce surgical time and post-operative infection rates compared with traditional glaucoma procedures. Little information however, has been published regarding complications and subsequent management.

Case presentation

The authors highlight five complicated cases of XEN® stent insertion, how they were managed and key learning points. Cases include: entire stent found at the bottom of the anterior chamber several months after uncomplicated insertion, stent broke into multiple pieces during manipulation within subconjunctiva, XEN45 stent migrated into the anterior chamber 7 months post-operatively and a case of limbal-based conjunctival dissection during open revision which lead to additional scarring around the stent and subsequent raised intraocular pressure.

Conclusions

We present some new and interesting complications of XEN implant as well as potential management options. This can assist clinical decision-making and enable better pre-operative discussions with patients regarding risks of surgery.

Change in visual acuity 12 and 24 months after transscleral ab interno glaucoma gel stent implantation with adjunctive Mitomycin C

PURPOSE

To analyze changes in best-corrected visual acuity (BCVA) after implantation of the transscleral ab interno glaucoma gel stent (XEN Gel Stent; Allergan, Dublin) in patients with open-angle glaucoma.

METHODS

In a single-center, prospective, non-randomized study of 137 eyes with open-angle glaucoma which underwent implantation with XEN, 69 eyes underwent XEN implantation alone (group 1) and 68 eyes underwent XEN implantation and cataract surgery (group 2). BCVA (Bailey-Lovie chart, logMAR scale) was evaluated at baseline, postoperative day 1, weeks 1 and 2, and months 1, 3, 6, 12, and 24. Risk factors for decline in BCVA were analyzed in multivariate models.

RESULTS

Baseline BCVA in group 1 was 0.21 ± 031; the group's mean BCVA did not change at any postoperative visit, although a ≥ 2-line loss of BCVA was detected in 15% (95% CI 7-29%) and 4% (95% CI 0-20%) after months 12 and 24, respectively. Baseline BCVA in group 2 was 0.33 ± 031; vision increased significantly at months 3 (0.22 ± 0.29, p = 0.015), 6 (0.20 ± 0.26, p = 0.006), 12 (0.18 ± 0.29, p = 0.001), and 24 (0.18 ± 0.29, p = 0.005). A ≥ 2-line loss of BCVA was reported in 4% (95% CI 1-15%) and 7% (95% CI 1-24%) after months 12 and 24, respectively.

CONCLUSIONS

There was no deterioration of BCVA in group 1; those in group 2 had an overall significant increase in BCVA. BCVA decrease was lower than is typically reported in the literature post-trabeculectomy.

Transcriptome analysis shows ambiguous phenotypes of murine primitive endoderm-related stem cell lines

Primitive endoderm (PrE)-related cell lines (XEN, pXEN and nEnd cells) show key features of the PrE. By transcriptome analysis, we show: (a) Compared to embryonic stem cells, PrE-related cell lines are less in vivo like, although early nEnd cells are most similar to the PrE. (b) These cell lines show post-PrE features of parietal (XEN and pXEN cells) or visceral (nEnd cells) endoderm, likely driven by Tgf-β and Wnt/Activin signaling, respectively. (c) pXEN and nEnd cell lines additionally show pre-PrE features. Hence, neither pXEN nor nEnd cell cultures represent a distinct in vivo entity. Rather, their properties are compatible with mixed and hybrid phenotypes. Our findings indicate that pre-PrE, PrE and early post-PrE phenotypes result from different niches, which need to be better understood to derive cell lines that distinctly represent the early stages of the extraembryonic endoderm.

Two-year results of a multicenter study of the ab interno gelatin implant in medically uncontrolled primary open-angle glaucoma

PURPOSE

To evaluate the effectiveness of an ab interno subconjunctival gelatin implant as primary surgical intervention in reducing intraocular pressure (IOP) and IOP-lowering medication count in medically uncontrolled moderate primary open-angle glaucoma (POAG).

METHODS

In this prospective, non-randomized, open-label, multicenter, 2-year study, eyes with medicated baseline IOP 18-33 mmHg on 1-4 topical medications were implanted with (phaco + implant) or without (implant alone) phacoemulsification. Changes in mean IOP and medication count at months 12 (primary outcomes) and 24, clinical success rate (eyes [%] achieving ≥ 20% IOP reduction from baseline on the same or fewer medications without glaucoma-related secondary surgical intervention), intraoperative complications, and postoperative adverse events were assessed.

RESULTS

The modified intent-to-treat population included 202 eyes (of 218 implanted). Changes (standard deviation) in mean IOP and medication count from baseline were - 6.5 (5.3) mmHg and - 1.7 (1.3) at month 12 and - 6.2 (4.9) mmHg and - 1.5 (1.4) at month 24, respectively (all P < 0.001). Mean medicated baseline IOP was reduced from 21.4 (3.6) to 14.9 (4.5) mmHg at 12 months and 15.2 (4.2) mmHg at 24 months, with similar results in both treatment groups. The clinical success rate was 67.6% at 12 months and 65.8% at 24 months. Overall, 51.1 (12 months) and 44.7% (24 months) of eyes were medication-free. The implant safety profile compared favorably with that published for trabeculectomy and tube shunts.

CONCLUSIONS

The gelatin implant effectively reduced IOP and medication needs over 2 years in POAG uncontrolled medically, with an acceptable safety profile. ClinicalTrials.gov registration number: NCT02006693 (registered in the USA).

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.

Migration of XEN45 Implant: Findings, Mechanism, and Management

Aim

The aim of this study is to report the mechanism of XEN migration and its management.

Background

Over the past decade, new less invasive surgical approaches for glaucoma have been devised and carried out successfully. One such technique is the use of the XEN gel stent. We present a rare and relatively unknown complication of XEN migration and present in detail the likely mechanism by which this occurs, and its subsequent management.

Case description

A 73-year-old male with primary angle closure on maximal medical treatment presented with an intraocular pressure of 30 mm Hg in the left eye. The visual acuity was 6/5, iridocorneal angles were open in all four quadrants, and the cup disc ratio was 0.4. As phacoemulsification alone was unlikely to adequately lower intraocular pressures, the patient underwent combined phacoemulsification and XEN implantation. Although the patient had a good postoperative result with pressures lowered to 11 mm Hg, 4 months after the operation, the XEN was found to have migrated 4 mm into the anterior chamber, associated with a low-grade uveitis. The patient subsequently had the XEN explanted a new XEN inserted. Pressures lowered 1 month postoperatively to 14 mm Hg.

Conclusion

XEN migration is likely due to a combination of mechanical and frictional forces. If the XEN is positioned such that more than 2 mm is in the subconjunctival space, the XEN is likely to be angled upward and, therefore, be more susceptible to these forces and undergo migration.

Clinical significance

It is essential that XEN implants are correctly sited and that this is confirmed intraoperatively to prevent the need for further procedures.

How to cite this article

Ali ZC, Khoo DI, et al. Migration of XEN45 Implant: Findings, Mechanism, and Management. J Curr Glaucoma Pract 2019;13(2):79–81.

[XEN-45 Gel Stent implant in glaucoma treatment]

The XEN-45 drainage implant is a hypotensive device made of hydrophilic gelatin and stabilized by glutaraldehyde. The implant is designed for modern Microinvasive Glaucoma Surgery (MIGS). Being installed ab interno, the stent drains aqueous fluid from the anterior chamber into the subconjunctival space. According to indications, XEN-45 can be used in treatment of primary open angle glaucoma, pseudoexfoliation or pigment glaucoma with uncompensated intraocular pressure amid maximum tolerated hypotensive therapy, and refractory glaucoma including cases with history of unsuccessful surgery. The implant can also be effectively used in combination with phacoemulsification. The article describes the structure and implantation process of the XEN drainage and reviews existing clinical trials on its effectiveness. The article also presents results on hypotensive efficacy of the implant, as well as characteristics and complications of postoperative management.

Systematic Literature Review of Clinical and Economic Outcomes of Micro-Invasive Glaucoma Surgery (MIGS) in Primary Open-Angle Glaucoma

INTRODUCTION

Primary open-angle glaucoma is estimated to affect 3% of the population aged 40-80 years. Trabeculectomy is considered the gold standard in surgical management of glaucoma; however, it is a technically complex procedure that may result in a range of adverse outcomes. Device-augmented, minimally invasive procedures (micro-invasive glaucoma surgeries, MIGS) have been developed aiming for safer and less invasive intraocular pressure (IOP) reduction compared with traditional surgery.

METHODS

This paper presents results from a systematic literature review conducted in accordance with National Institute for Health and Care Excellence requirements for the Medical Technology Evaluation Programme via multiple databases from 2005 to 2016. For clinical outcomes, randomized clinical trials (RCTs) comparing MIGS with trabeculectomy or other therapies, observational studies, and other non-RCTs were included. Clinical outcomes reviewed were the change from baseline in mean IOP levels and change in topical glaucoma medication. Safety was assessed by reported harm and adverse events. For economic evidence, trials on cost-effectiveness, cost-utility, cost-benefit, cost-consequences, cost-minimization, cost of illness, and specific procedure costs were included. Risk of bias was assessed for clinical studies using the Cochrane Risk of Bias tool.

RESULTS

A total of nine RCTs (seven iStents^®, one Hydrus^®, and one CyPass^®), seven non-RCTs (three iStent^®, three CyPass^®, and one Hydrus^®), and 23 economic studies were analyzed. While various forms of trabeculectomy can achieve postoperative IOP of between 11.0 and 13.0 mmHg, MIGS devices described in this review were typically associated with higher postoperative IOP levels. In addition, MIGS devices may result in increased hypotony rates or bleb needling in subconjunctival placed devices, requiring additional medical resources to manage. There is limited available evidence on the cost-effectiveness of MIGS and therefore it remains unclear whether the cost of using MIGS is outweighed by cost savings through decreased medication and need for further interventions.

CONCLUSION

Larger randomized trials and real-world observational studies are needed for MIGS devices to better assess clinical and economic effectiveness. Given the shortage of published data and increasing use of such procedures, living systematic reviews may help to provide ongoing and timely evidence-based direction for clinicians and decision makers. This review highlights the current unmet need for treatments that are easy to implement and reduce long-term IOP levels without increasing postoperative aftercare and cost.

FUNDING

Santen GmbH, Germany.

XEN Gel Implant: a new surgical approach in glaucoma

INTRODUCTION

Glaucoma is a leading cause of blindness worldwide. Intraocular pressure (IOP) lowering is the only effective treatment strategy. Traditional glaucoma surgeries are generally considered to be unpredictable and associated with a high rate of complications. This has led to the development of a novel XEN Gel Implant, a type of minimally invasive glaucoma surgery (MIGS), lowering the IOP without extensive surgical dissection.

AREAS COVERED

A literature search was undertaken on PubMed using the terms XEN glaucoma, gelatin microstent, and MIGS. All the articles and case reports on XEN Gel Implant and selected articles on MIGS were studied and reviewed. We have discussed the results of most studies on XEN Gel Implant related to its efficacy, safety and success.

EXPERT COMMENTARY

The XEN Gel Implant effectively lowers IOP and medication use, with a favorable safety profile. Long-term data on its success and cost-effectiveness are lacking. The studies have shown it to be without any serious adverse events and to have good safety profile encouraging future research on this novel implant. There is a need to correctly identify selection criteria for patients, who would benefit the most from the XEN Gel Implant.

PDGFRA Is Not Essential for the Derivation and Maintenance of Mouse Extraembryonic Endoderm Stem Cell Lines

Extraembryonic endoderm stem (XEN) cell lines can be derived and maintained in vitro and reflect the primitive endoderm lineage. Platelet-derived growth factor receptor alpha (PDGFRA) is thought to be essential for the derivation and maintenance of mouse XEN cell lines. Here, we have re-evaluated this requirement for PDGFRA. We derived multiple PDGFRA-deficient XEN cell lines from postimplantation and preimplantation embryos of a PDGFRA-GFP knockout strain. We also converted PDGFRA-deficient embryonic stem cell lines into XEN cell lines chemically by transient culturing with retinoic acid and Activin A. We confirmed the XEN profile of our 12 PDGFRA-deficient cell lines by immunofluorescence with various markers, by NanoString gene expression analyses, and by their contribution to the extraembryonic endoderm of chimeric embryos produced by injecting these cells into blastocysts. Thus, PDGFRA is not essential for the derivation and maintenance of XEN cell lines.

•

PDGFRA is thought to be essential for extraembryonic endoderm stem (XEN) cells

•

We derived multiple XEN cell lines from a PDGFRA-GFP knockout strain

•

We chemically converted PDGFRA-deficient ESC lines into XEN cell lines

•

Thus, PDGFRA is not essential for the derivation and maintenance of XEN cells

Micro-invasive glaucoma surgery (MIGS): a review of surgical procedures using stents

Over the last decade several novel surgical treatment options and devices for glaucoma have been developed. All these developments aim to cause as little trauma as possible to the eye, to safely, effectively, and sustainably reduce intraocular pressure (IOP), to produce reproducible results, and to be easy to adopt. The term “micro-invasive glaucoma surgery (MIGS)” was used for summarizing all these procedures. Currently MIGS is gaining more and more interest and popularity. The possible reduction of the number of glaucoma medications, the ab interno approach without damaging the conjunctival tissue, and the probably safer procedures compared to incisional surgical methods may explain the increased interest in MIGS. The use of glaucoma drainage implants for lowering IOP in difficult-to-treat patients has been established for a long time, however, a variety of new glaucoma micro-stents are being manufactured by using various materials and are available to increase aqueous outflow via different pathways. This review summarizes published results of randomized clinical studies and extensive case report series on these devices, including Schlemm’s canal stents (iStent^®, iStent^® inject, Hydrus), suprachoroidal stents (CyPass^®, iStent^® Supra), and subconjunctival stents (XEN). The article summarizes the findings of published material on efficacy and safety for each of these approaches.

An Update on Implants for Minimally Invasive Glaucoma Surgery (MIGS)

For several years, the gold standard for surgical treatment of glaucoma has been trabeculectomy. Although very successful at reducing intraocular pressure (IOP), there are several potential complications of trabeculectomy, including sight-threatening ones. This has stimulated much research aimed at the development of new and effective procedures to lower IOP with an enhanced safety profile. Minimally invasive glaucoma surgery (MIGS) procedures prioritise patient safety but also demonstrate efficacy in reducing IOP. We performed an online search of peer-reviewed literature using PubMed, entering keywords relevant to this clinical discipline. In summary, there is a lack of long-term safety and efficacy data, a lack of comparative data and a lack of data on standalone (i.e. without simultaneous cataract surgery) procedures. Most implants are not yet FDA approved. Although not exhaustive, since it does not discuss MIGS procedures that are not implants, this article summarises the range of different MIGS implants that are available to the ophthalmic surgeon.