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Meta-Analysis
. 2022 Jul 15;22(1):305.
doi: 10.1186/s12886-022-02502-y.

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

Xiang Yang  1 , Yang Zhao  1 , Yu Zhong  1   2 , Xuanchu Duan  3   4
Affiliations
Meta-Analysis

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

Xiang Yang et al. BMC Ophthalmol. .

Abstract

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.

Keywords: Meta-analysis; Minimally invasive glaucoma surgery; XEN.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
PRISMA 2009 flow diagram. The search strategy for this meta-analysis yielded 725 publications, and 429 studies were excluded because of duplication. After reading the titles and abstracts, 57 studies were excluded. Two hundred and thirty-nine possible full-text studies were carefully reviewed (Animal study [n = 4]; Case report [60]; Letter and Response [n = 8]; Review and meta-Analysis [n = 64]). Finally, 78 trials were included for quantitative analysis
Fig. 2
Fig. 2
Meta-analysis of XEN-only surgery compared with phaco-XEN for NOAM after surgery. The total study sample included 618 eyes undergoing XEN only and 415 eyes undergoing phaco-XEN. Overall analysis of NOAM after surgery (SMD: 0.09, 95% CI -0.04 to 0.23, p value 0.170)had no difference between two groups
Fig. 3
Fig. 3
Meta-analysis of XEN-only surgery compared with phaco-XEN for IOP by follow-up duration after surgery. The total study sample included 1314 eyes undergoing XEN-only surgery and 1160 eyes undergoing phaco-XEN. Overall analysis of IOP after surgery (SMD: -0.01, 95% CI -0.09 to 0.08, p value 0.894)had no difference between two groups
Fig. 4
Fig. 4
Meta-analysis of XEN-only surgery compared with phaco-XEN for bleb needing rate. The total study sample included 220 eyes undergoing XEN-only surgery and 443 eyes undergoing phaco-XEN surgery. Overall bleb needling rate was significantly high in XEN-only group (RR: 1.45, 95% CI 1.06to 1.99, p value 0.019)
Fig. 5
Fig. 5
Meta-analysis of XEN surgery compared with trabeculectomy procedure for IOP before surgery. The total study sample included 281 eyes undergoing XEN-only surgery and 332 eyes undergoing trabeculectomy procedure. Overall analysis of IOP before surgery (SMD: -0.33, 95% CI -0.49 to -0.16, p value < 0.001) was lower in trabeculectomy procedure group
Fig. 6
Fig. 6
Meta-analysis of XEN surgery compared with trabeculectomy procedure for IOP after surgery. The total study sample included 281 eyes undergoing XEN-only surgery and 332 eyes undergoing trabeculectomy procedure. Overall analysis of IOP after surgery (SMD: 0.14, 95% CI -0.18 to 0.46, p value < 0.388) had no difference between two groups
Fig. 7
Fig. 7
Meta-analysis of XEN surgery compared with trabeculectomy procedure for bleb needing rate. The total study sample included 371 eyes undergoing XEN-only surgery and 363 eyes undergoing trabeculectomy procedure. Overall bleb needling rate was significantly high in XEN-only group (RR: 2.42, 95% CI 1.33 to 4.43, p value 0.004)
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