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  • Ab Interno Versus Ab Externo Placement of the Xen45 Gel Stent

    By Jean Shaw
    Selected by Henry D. Jampel, MD, MHS
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    Journal Highlights

    Ophthalmology Glaucoma, January/February 2023

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    Ruda et al. set out to compare the effectiveness of ab interno versus ab externo placement of Xen45 gel stents in patients with refractory open-angle glaucoma (OAG). They found that the off-label ab externo approach produced comparable outcomes to the more established ab interno placement.

    For this single-center retrospective comparative case series, the researchers evaluated 89 patients (89 eyes) with OAG. Group 1 (n = 29) underwent ab interno positioning of the stent, while group 2 (n = 60) had ab exter­no placement. All were treated by the same surgeon between 2017 and 2020. Outcomes were recorded at each fol­low-up visit from post-op day 1 up to 24 months (median follow-up, 12 and eight months for group 1 and 2, respec­tively). The primary outcome measure was the rate of surgical success at the eight-month mark. (Surgical failure was defined as inadequate IOP control or explantation of the stent owing to erosion, including the need for open revisions with tenonectomy or repeat Xen45 placement.) Secondary measures included postoperative IOP and med­ication usage, complication rates, and bleb revision rates.

    At eight months, success rates were 72% in group 1 and 74% in group 2. There was no difference in the median time to failure between the groups (p = .98). Complication rates and bleb revision rates were comparable between both groups, with approximately one-third of patients developing compli­cations and one-fourth requiring bleb needling, regardless of group.

    With regard to IOP and medication usage, the findings were as follows:

    • Mean baseline IOPs were 22.8 ± 7.5 mm Hg on 3.8 ± .9 medications in group 1 and 25.3 ± 10.7 mm Hg 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 mm Hg on 2.2 ± 1.4 medications in group 1 and 12.2 ± 2.1 mm Hg on 1.8 ± 1.3 medications in group 2.

    The researchers noted limitations of the study, including its retrospec­tive design, with some patients lost to follow-up. In addition, the surgeon started with the ab interno approach and adopted the ab externo technique later on, thus introducing the possibili­ty of bias. Finally, given the sample size, this study was underpowered for direct comparison in surgical success rates between the two approaches. Larger studies with longer follow-up are needed.

    The original article can be found here.