Efficacy and Safety of Ab-externo Approach versus Ab-interno Approach of XEN45 Gel Stent Implantation: A Systematic...

The XEN45 Gel Stent is a microinvasive glaucoma surgery (MIGS) device designed to lower intraocular pressure (IOP) by enhancing aqueous humor outflow. This systematic review and meta-analysis aimed to compare efficacy and safety of the ab externo and ab interno approaches for XEN45 Gel Stent implantation.

A comprehensive literature search was conducted using PubMed, Web of Science, the Cochrane Library, the Registry of Controlled Trials, and the Directory of Open Access Journals. Of 216 screened articles, six retrospective studies met inclusion criteria. Primary outcomes included reduction in mean baseline IOP and number of IOP-lowering medications required postoperatively. Statistical analysis was performed using Stata (StataCorp, 2025).

A total of 614 eyes were analyzed. Three hundred and eighteen treated with the ab externo approach and 278 with the ab interno approach. Mean patient age was comparable between groups, although proportion of female patients was higher in the ab externo cohort. Both techniques achieved significant IOP reduction: pooled standardized mean difference (SMD) was -12.8 (95% CI: -19.4 to -6.2) for ab externo group and -10.1 (95% CI: -16.3 to -3.8) for ab interno group. Reduction in IOP-lowering medications was also significant and similar between groups [ab externo: SMD -2.2 (95% CI: -2.6 to -1.9); ab interno: SMD -2.1 (95% CI: -2.5 to -1.7)]. Needling rates were significantly lower with ab externo approach compared to ab interno approach (12.1% vs 18.1%, p = 0.04). Although rate of secondary glaucoma surgeries was higher in ab interno group (19.8% vs 11.6%), this difference did not reach statistical significance (p = 0.28).

Both ab externo and ab interno XEN45 Gel Stent implantation techniques demonstrated comparable efficacy and safety in lowering IOP and reducing dependence on IOP-lowering medications. However, ab externo approach was associated with a lower needling rate, suggesting a potential procedural advantage.