Abstract
PurposeXEN 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.MethodsWe 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.ResultsFive 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%.ConclusionsXEN 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.
Highlights
Invasive glaucoma surgeries (MIGSs) are surgical interventions for mild or moderate glaucoma via the ab-interno or ab-externo approach for lowering intraocular pressure (IOP) with minimal or no scleral dissection, aiming to provide a safe profile and rapid recovery compared with traditional surgery [1, 2]
The inclusion criteria were as follows: [1] prospective or retrospective case series or cohort; [2] glaucoma patients without restriction for age, sex, ethnicity, use of antiglaucoma medications; [3] XEN implantation combined with phacoemulsification or not; and [4] IOP, antiglaucoma medications, success rate, failure rate, reoperation rate, and complications
The multicentre studies by Kirwan et al [85] of 428 eyes and the Tube vs. Trabeculectomy (TVT) study [87] of 117 eyes confirmed a higher rate of IOP reduction with trabeculectomy of 46.1 and 46.0% over 2 and 3 years of follow-up, respectively, when comparing the IOP reduction of XEN to trabeculectomy. which was much higher than we reported in our review on XEN implantation (35%)
Summary
Invasive glaucoma surgeries (MIGSs) are surgical interventions for mild or moderate glaucoma via the ab-interno or ab-externo approach for lowering intraocular pressure (IOP) with minimal or no scleral dissection, aiming to provide a safe profile and rapid recovery compared with traditional surgery [1, 2]. MIGSs always target Schlemm’s canal and the suprachoroidal space to lower IOP, which is the main complement of outflow resistance in the pathophysiology of glaucoma, whereas the XEN gel stent is the first MIGS procedure to drain aqueous to subconjunctival space. It is a 6-mm hydrophilic tube of a collagen-derived gelatin cross-linked with glutaraldehyde to prevent degradation in the tissue given the lack of a foreignbody reaction [3]. The outflow resistance was 0–1, 2–3, and 6–8 mmHg for devices with inner diameters of 140, 63, and 45 μm, respectively [5,6,7]. To exclude the difference in outcomes caused by different inner diameters, the meta-analysis only included the studies focused on the devices with inner diameter of 45 μm
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