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

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.

XEN Gel Stent Versus Nonpenetrating Deep Sclerectomy in Ocular Hypertension and Open Angle Glaucoma Patients

PRCIS

XEN gel stent and nonpenetrating deep sclerectomy, both either alone or in combination with cataract surgery, significantly lowered the intraocular pressure (IOP) and reduced the number of antiglaucoma medications in patients with open angle glaucoma, with no significant differences between them.

PURPOSE

To compare the surgical outcomes of XEN45 implant and nonpenetrating deep sclerectomy (NPDS), either alone or in combination with cataract surgery, in patients with ocular hypertension and open angle glaucoma (OAG). A retrospective and single-center cohort study was conducted on consecutive patients who underwent a XEN45 implant or an NPDS, either alone or in combination with phacoemulsification. The primary endpoint was the mean change in IOP from the baseline to the last follow-up visit. One hundred twenty-eight eyes, 65 (50.8%) eyes in the NPDS group and 63 (49.2%) eyes in the XEN group, were included in the study. The mean preoperative IOP was significantly lowered from 17.6±5.3 mm Hg and 17.8±6.2 mm Hg to 12.6±2.6 mm Hg and 13.8±2.8 mm Hg at month 12 in the XEN and NPDS groups, respectively; P <0.0001 each. At month 12, 70 (54.7%) eyes were classified as a success, with no significant differences between XEN (57.1%; 36/63 eyes) and NPDS (52.3%; 34/65 eyes) (mean difference: 4.8%; 95% CI: -30.5% to 20.8%; P =0.7115). The number of ocular hypotensive medications was significantly reduced in the XEN (from 2.1±0.7-0.2±0.5, P <0.0001) and in the NPDS (from 2.0±0.8 to 0.3±0.6, P <0.0001) groups, with no significant differences between them ( P =0.2629). The incidence of postoperative adverse events in the overall study population was 12.5%, with no significant differences between groups ( P =0.1275). Seven (11.1%) eyes underwent needling (XEN group) and 10 (15.4%) goniopuncture (NPDS group); P =0.4753.

CONCLUSIONS

XEN45 implant and the NPDS, either alone or in combination with cataract surgery, significantly lowered IOP and reduced the number of ocular hypotensive medications in ocular hypertension and patients with open angle glaucoma.

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.

One-Year Outcomes of Standalone XEN Gel Stent Versus Nonpenetrating Deep Sclerectomy

PRCIS

The nonpenetrating deep sclerectomy (NPDS) procedure resulted in significantly more surgical success than the standalone XEN gel stent procedure without differences in safety profile.

PURPOSE

The purpose of this study was to compare surgical success and safety profile of NPDS and XEN gel stent.

METHODS

A retrospective chart review of 328 eyes of 282 patients who were scheduled for standalone XEN gel stent surgery (n=140) or NPDS (n=188) at Groupe Hospitalier Paris Saint-Joseph between January 2017 and December 2018 was conducted. Primary outcome measure was the proportion of surgical success 12 months after surgery. Complete and qualified surgical successes were defined by intraocular pressure (IOP)≤18 mm Hg and a reduction of IOP≥20% without or with hypotensive medication, respectively.

RESULTS

In total, 82 eyes were included in the XEN group and 124 eyes in the NPDS group. In the 1-eye analysis, rates of "complete success" and "qualified success" were, respectively, at the end of follow-up, 28.57% and 20.00% in the XEN group, and 42.72% and 16.50% in the NPDS group ( P =0.17). Success probability plots based on the Kaplan-Meier estimate for overall surgical success demonstrated a median success probability time of 3.73 years for the NPDS group and 2.38 years for the XEN group ( P <0.0001). After adjustment for confounding variables using Cox regression, the NPDS procedure was significantly more associated with surgical success than the XEN gel stent implantation ( P <0.001). No difference was demonstrated in terms of reduction of antiglaucoma medications, needling procedures, or reoperations.

CONCLUSIONS

The NPDS procedure may be more effective than the XEN gel stent in reducing IOP in patients with open angle glaucoma and may result in longer surgical success. However, a well-conducted prospective randomized study is required to confirm these results.

XEN Gel Stent Implantation in Eyes With Previous Glaucoma Filtering Surgeries: A Case Series

Background In this study, we aimed to analyze the efficacy and safety of ab interno XEN^® gel stent (Allergan Inc., Dublin, Ireland) implantation in a series of eyes with open-angle glaucoma and a history of previous filtering glaucoma surgeries. Methodology This retrospective, single-center study included all eyes that underwent XEN gel implantation with a minimum follow-up of 18 months that had previously undergone a filtering glaucoma surgery. The main outcomes were intraocular pressure (IOP) variation (baseline, first day, first week, and first, third, sixth, 12th, and 18th months), the number of hypotensive eyedrops at 18 months, intraoperative and postsurgical complications, and the need for subsequent glaucoma surgery. Results A total of 10 eyes from nine patients were enrolled in the study. IOP significantly decreased from 24.0 ± 2.4 mmHg to 7.8 ± 1.6 mmHg on the first day, 9.4 ± 2.2 mmHg in the first week, and 12.3 ± 4.8 mmHg, 14.7 ± 4.3 mmHg, 13.3 ± 3.8 mmHg, 11.7 ± 1.9 mmHg, and 12.3 ± 1.9 at the first, third, sixth, 12th, and 18th month, respectively (p < 0.001), with a 49.5% reduction in IOP at the end of the follow-up. The number of hypotensive eyedrops decreased significantly from 3.5 ± 0.5 (3-4) to 0.7 ± 0.7 (0-2) (p = 0.026). No intraoperative or postsurgical complications were recorded. In total, seven (70%) eyes achieved controlled IOP of <18 mmHg without any anti-glaucomatous medications, and one (10%) eye with the use of topical prostaglandin. One (10%) eye was submitted to a surgical revision, and another needed an additional glaucoma surgery during follow-up, with appropriate IOP control at the last follow-up. Conclusions This case series aims to highlight that the XEN implant can be an option in eyes with IOP levels in the low 20s and previously failed filtering surgeries, with satisfactory efficacy and high safety.

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.