Results of fluorouracil-augmented Xen45 implantation in primary open-angle and pseudoexfoliation glaucoma

Double implantation of Xen 45 gel stent in primary open-angle glaucoma: a pilot study

PURPOSE

To describe the outcomes of double implantation of Xen 45 Gel Stent (Xen) using an ab externo approach with closed conjunctiva.

METHODS

Retrospective single-centre case series of primary open-angle glaucoma patients with at least six months of follow-up after implantation of a second Xen in the same eye via ab externo technique without conjunctival opening.

RESULTS

Eight pseudophakic eyes of 8 patients were included. Intraocular pressure (IOP) dropped from 30 ± 2.6 mmHg pre-operatively to 22.4 ± 2.3 mmHg one month after the first Xen implant (mean difference: -7.6 mmHg [95% confidence interval: -9.4, -5.9 mmHg], p = 0.0092). A second Xen was then implanted to achieve the target IOP. The procedure showed no significant intraoperative or postoperative complications. The IOP dropped to 16.1 ± 2.7 mmHg six months following this second implant (mean difference: -6.3 mmHg [95% confidence interval: -7.2, -5.3 mmHg], p = 0.0183); however, 3 patients needed medical therapy to further reduce the IOP towards the target value.

CONCLUSION

Sequential implantation of two Xen 45 Gel Stents using an ab externo approach with closed conjunctiva appears a promising procedure that showed a favorable safety and efficacy profile in this small case series. This pilot data might pave the way for further studies to evaluate the safety and efficacy of the procedure.

Intraocular Pressure and Medication Changes Associated with Xen Gel Stent: A Systematic Review of the Literature

The Xen gel stent (Allergan Inc, an AbbVie company; Dublin, Ireland) was conceived as an option for patients requiring modest IOP reduction but for whom trabeculectomy was not yet indicated. As with any glaucoma surgery, establishing criteria for patient selection and identifying factors that contribute to a high likelihood of success are important. To help guide clinical decision-making, a systematic review of published studies on the gel stent was performed, with the goal of understanding postoperative outcomes based on clinical and patient factors. Results were organized around a series of pertinent clinical questions based on scenarios encountered in clinical practice. Criteria for including studies were intentionally broad, with the objective of simulating the diverse population of glaucoma patients encountered in real-world practice. Outcomes for IOP and medication reduction postoperatively were assessed in various analyses, including in eyes with various glaucoma types and severity; in eyes naïve to surgery as well as those with a history of prior incisional glaucoma surgery; and when surgery was performed as a standalone procedure or at the time of cataract surgery. The results of each of the various analyses were consistent in demonstrating that successful gel stent surgery achieved a postoperative IOP of approximately 14.0 mm Hg and reduction to fewer than 1 glaucoma medication. Additional data are shown on outcomes by method of implant (ab interno vs ab externo); intraoperative use of antifibrotics; and rates of needling in published studies.

Minimally Invasive Glaucoma Surgery: Safety of Individual Devices

Primary open-angle glaucoma progression in those already on maximal medical therapy has traditionally been treated with trabeculectomy, a surgical procedure that carries a high degree of morbidity. In the last few decades, significant advances have been made in the field of minimally invasive glaucoma surgery (MIGS) devices, which aim to defer or prevent trabeculectomy via less arduous surgical techniques in certain types of glaucoma. Although reviews have been published examining the efficacy of various MIGS techniques, no article synthesises the comparative safety of all available devices. We performed a literature review examining the safety of MIGS devices. Fifteen devices were included, variously attempting to increase aqueous outflow through the trabecular meshwork or the suprachoroidal space, shunting into the subconjunctival space, or reducing aqueous production through ciliary body ablation. Notably, the earliest product attempting to increase outflow to the suprachoroidal space, Alcon's CyPass Micro-Stent, was withdrawn from the market due to concerns regarding increased corneal endothelial cell loss at five years post-implantation. All other devices were described as well-tolerated, with the most common adverse effects including hyphaema, intraocular pressure spikes, and device migration or obstruction. MIGS devices are purported to be uniformly safe, and many studies report no statistically significant increased complications beyond those associated with cataract surgery alone. It is important to note, however, the generally poor quality of current studies, with a dearth of randomised, or even prospective, data, and a large proportion of studies funded by device producers.

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.

The Outcomes of XEN Gel Stent Implantation: A Systematic Review and Meta-Analysis

Purpose

XEN gel stents are used for the treatment of open-angle glaucoma (OAG), including primary and secondary glaucoma that are uncontrolled by previous medical therapy and cases with previous failed surgery. Our aim was to systematically review of the clinical data of currently published ab-interno XEN gel stents with an emphasis on intraocular pressure (IOP), antiglaucoma medication outcomes, and safety profiles.

Methods

We analyzed all of the publications (MEDLINE, EMBASE, Cochrane Library) on the ab-interno XEN gel stent to evaluate the reduction in IOP and antiglaucoma medications following the procedure. The primary outcomes measured for the meta-analysis were reduction in IOP and anti-glaucoma medications. The secondary outcome were adverse events. For each study, we used a random effects analysis model to calculate the mean difference and 95% confidence intervals for the continuous results (reduction in IOP and antiglaucoma medications) using the inverse variance statistical method.

Results

Five hundred twenty-seven articles were checked and 56 studies were found to be relevant with a total of 4,410 eyes. There was a significant reduction in IOP as well as in the number of medications required in patients treated with ab-interno XEN implant either alone or combined with cataract surgery. This new treatment for various types of glaucoma reduced the IOP by 35% to a final average close to 15 mmHg. This reduction was accompanied by a decrease in the number of antiglaucoma medications in all the studies, approximately 2 classes of medication at the price of more needlings. The overall complete success rate was 21.0–70.8% after 2 years using strict criteria originally designed to record success rate in filtration surgery. The incidence of complications vision-threatening was low at <1%.

Conclusions

XEN gel stent was effective and safe for primary and secondary OAG. Further studies should be performed to investigate the impact of ethnicity on the success and failure rate after XEN implantation.

Late-onset Endophthalmitis after XEN45® Implantation: A Retrospective Case Series and Literature Review

AIM AND OBJECTIVE

To report the incidence of late-onset endophthalmitis following XEN45® stent implantation.

BACKGROUND

Long-term safety profile and efficacy in relation to the so-called microinvasive glaucoma surgery (MIGS) techniques are still under evaluation. The XEN45® gel stent entails a bleb formation and often requires postoperative conjunctival management, differing from the current reviewed concept of minimally invasive procedures. Endophthalmitis has been described among the complications, triggered in the majority of cases by tube extrusion.

CASES DESCRIPTION

From our chart of 293 eyes operated on between November 2016 and November 2019, five (1.7%) patients developed endophthalmitis, which took place in the months 3, 4, 5, 11, and 14 after surgery, respectively. Sixty percent had undergone previous needling procedures. All of them showed a previous flat bleb and developed perforation of the conjunctiva caused by the distal portion of the tube. One patient was early eviscerated due to a fateful course. Treatment consisted of intravitreal, oral, and topical antibiotics, as well as topical corticosteroids. Eighty percent underwent device withdrawal, conjunctival gap suturing, anterior chamber washout, aqueous humor (AH) tab extraction (one positive for S. epidermidis and one for Streptococcus agalactiae), and pars plana vitrectomy. A second patient was eviscerated due to phthisis bulbi. Out of three remaining patients, one underwent vitrectomy for retinal detachment, while two patients required glaucoma surgery for intraocular pressure control. The final VA was ≤20/125 in all patients.

CONCLUSION

The XEN45® device appears to trigger endophthalmitis by extruding the stent or unnoticed leakage through conjunctival defects. Special attention should be paid to flat and avascular blebs.

CLINICAL SIGNIFICANCE

This series shows a higher rate of endophthalmitis (1.7%) compared with previous studies with a significant sample size (0.4-1.4%).

HOW TO CITE THIS ARTICLE

Burggraaf-Sánchez de las Matas R, Such-Irusta L, Alfonso-Muñoz EA, et al. Late-onset Endophthalmitis after XEN45® Implantation: A Retrospective Case Series and Literature Review. J Curr Glaucoma Pract 2021;15(3):153-160.

Efficacy of the XEN-Implant in Glaucoma and a Meta-Analysis of the Literature

Background: To assess the efficacy of XEN-implant surgery in patients with glaucoma, and to perform a meta-analysis of previously published results and compare these to our data. Methods: Prospective case-control study, in which all eyes that underwent XEN-implant surgery were included from 2015 onwards. Sub-analyses were performed for eyes that underwent XEN-implant as standalone procedure and as cataract-combined procedure. To compare our results, a systematic review was performed using the Embase, PubMed, Web of Science, and Cochrane database. Meta-analyses were performed by combining data (intraocular pressure (IOP), IOP-lowering medication, and complications) from the retrieved studies. Results: A total of 221 eyes underwent XEN-implant surgery (124 standalone and 97 cataract-combined). The mean ± standard deviation IOP declined from 18.8 ± 6.5 to 13.5 ± 4.3 mmHg at the last follow-up (p < 0.001; 28.9%). Postoperative, no significant differences in IOP or IOP-lowering medication were found between patients with and without combined procedure. Secondary surgeries were performed in 20.8% of eyes, most of them (63.0%) within six months. A meta-analysis of 19 studies retrieved from the systematic review showed a two-years postoperative pooled mean (weighted mean difference) of 14.5 (7.3) mmHg and 1.0 (1.6) for IOP and IOP-lowering medications, respectively (compared to 13.5 (5.3) mmHg and 3.2 (2.4) in the current study). Conclusion: XEN-implant surgery was effective and safe in lowering IOP and the number of IOP-lowering medications. There were no differences between standalone and combined procedures.