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Carlo Alessandro Lavia, Roberta Spinetta, Giulia Consolandi, Giulia Pignata, Paola Cannizzo, Vittoria Aragno, Antonio Maria Fea; Xen Gel Stent: efficacy, safety and filtering bleb analysis at one year. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4986.
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© ARVO (1962-2015); The Authors (2016-present)
The Xen Gel Stent is a minimally invasive glaucoma surgery (MIGS) device that creates a shunt between the anterior chamber and the subconjunctival space, resulting in a subconjunctival filtering bleb.Aim of this study was to retrospectively evaluate the efficacy and safety of this new MIGS device and to provide a micro and macroscopic assessment of the filtering bleb to identify predictive prognostic factors
12 eyes (11 patients) with uncontrolled primary open angle glaucoma with maximal topical glaucoma therapy underwent stent implantation. Intraocular pressure (IOP), number of glaucoma medications, best corrected visual acuity (BVCA), endothelial cell density (ECD), visual field mean deviation (MD; 24-2 Humphrey Field Analyzer) were measured at baseline and follow-up (FU). Bleb assessment was performed using in vivo confocal microscopy (IVCM) for mean conjunctival microcysts density (MMD) and area (MMA) and subepithelial connective tissue density and anterior segment-OCT (AS-OCT) for bleb wall reflectivity. IVCM images were processed using ImageJ software.Postoperative IOP <18 mmHg with or without glaucoma medication was defined as qualified or complete success respectively. IOP > 18 mmHg was defined as failure.
Success was achieved in 10 eyes (5 qualified, 5 complete), failure in 1 eye while one patient was lost at FU. Mean IOP decreased from 21,8±2,8 to 15,2±2,2mmHg(p<0.01). BCVA,MD and endothelial cell density didn't change(p>0.05).Mean MMD significantly increased(p<0.01) in the conjunctiva overlying the implant. Microcysts showed a clustered pattern rather than diffuse found at baseline. Appropriate placement of the device was detected using AS-OCT in all eyes. Bleb wall reflectivity at AS-OCT significantly changed as compared to baseline in all eyes. Nasal and central conjunctival connective density at IVCM and bleb wall reflectivity at AS-OCT were significantly lower in complete success patients as compared with failure(p<0.05).
Xen stent provides a significant decrease in IOP and in number of glaucoma medications and shows a good safety profile. Low connective density and bleb wall reflectivity respectively observed at IVCM and AS-OCT may reflect a loosely arranged subepithelial connective tissue and represent the main predictive factor of successful surgery. IVCM and AS-OCT are useful tools that can help clinicians in the postoperative evaluation of the XEN stent.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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