Efficacy of ab-interno gelatin microstent implantation in primary and refractory glaucoma

Published:March 23, 2022DOI:



      To evaluate the outcomes of ab interno gelatin microstent implantation alone and in combination with phacoemulsification for the reduction of intraocular pressure (IOP).


      Retrospective cohort study.


      141 eyes of 141 patients with any glaucoma subtype, including refractory glaucoma, operated in the Centre Hospitalier de l'Université de Montréal (CHUM) from 2015-2018. Patients were included if they were over 40 years of age and had a preoperative IOP of >18 mm Hg on maximum tolerated medical therapy.


      All patients received ab-interno microstent implantation (XEN-45, Allergan, Madison, NJ) with mitomycin C +/- combined phacoemulsification. The primary outcome was complete surgical success (IOP 6-18 mm Hg and <20% reduction from baseline without IOP medications or reoperations or cyclophotocoagulation); secondary outcomes included qualified success allowing for medications, percentage reduction in mean IOP and medications, and reduction in number of complications, interventions, and reoperations.


      Mean follow-up was 30.5 ± 10.2 months (±SD). Mean IOP was 23.3 ± 7.0 mm Hg on 3.4 ± 0.8 medications at baseline and 13.3 ± 4.7 mm Hg on 1.9 ± 1.5 medications at 24 months of follow-up (p < 0.001). From 24-month survival analysis estimates, complete success was achieved in 34.1% of microstent eyes versus 20.7% with combined phacoemulsification (p = 0.02); 79.1% versus 75.1% achieved qualified success, respectively (p = 0.86). Cases with combined phacoemulsification had a higher rate of failure (hazard ratio [HR] = 1.6, 95% CI 1.1–2.3, p = 0.02). Needling with mitomycin-C or 5-fluorouracil postoperatively occurred in 54 eyes (38.3%). Complications included transient hypotony (10.6%), transient hyphema (6.4%), macular edema (4.3%), and microstent exposure (2.8%). There were 33 eyes (23.4%) with reoperations and 14 (9.9%) requiring subsequent cyclophotocoagulation lasers.


      Microstent implantation required topical therapy in most cases 24 months following surgery in primary and refractory glaucoma and, when combined with phacoemulsification, had a higher risk of failure.
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        • Tham Y
        • Li X
        • Wong TY
        • et al.
        Global Prevalence of Glaucoma and Projections of Glaucoma Burden through 2040 A Systematic Review and Meta-Analysis.
        Ophthalmology. 2014; 121: 2081-2090
        • Heijl A
        • Leske MC
        • Bengtsson B
        • et al.
        Reduction of Intraocular Pressure and Glaucoma Progression: Results From the Early Manifest Glaucoma Trial.
        JAMA Ophthalmol. 2002; 120: 1268-1279
        • Prum BE
        • Rosenberg LF
        • Gedde SJ
        • et al.
        Primary Open-Angle Glaucoma Preferred Practice Pattern® Guidelines.
        Ophthalmology. 2016;
        • Jiang N
        • Zhao G-Q
        • Lin J
        • et al.
        Meta-analysis of the efficacy and safety of combined surgery in the management of eyes with coexisting cataract and open angle glaucoma.
        Int J Ophthalmol. 2018; 11: 279-286
        • Brubaker RF
        • Pederson JE.
        Ciliochoroidal detachment.
        Surv Ophthalmol. 1983; 27: 281-289
        • Wallin O
        • Al-ahramy AM
        • Lundstrom M
        • Montan P
        Endophthalmitis and severe blebitis following trabeculectomy. Epidemiology and risk factors; a single-centre retrospective study.
        Acta Ophthalmol. 2014; 92: 426-431
        • Freedman J
        • Gupta M
        • Bunke A.
        Endophthalmitis After Trabeculectomy.
        JAMA Ophthalmol. 1978; 96: 1017-1018
        • Kirwan JF
        • Lockwood AJ
        • Shah P
        • et al.
        Trabeculectomy in the 21st century: A multicenter analysis.
        Ophthalmology. 2013;
        • Saheb H
        • Ahmed IIK.
        Micro-invasive glaucoma surgery: Current perspectives and future directions.
        Curr Opin Ophthalmol. 2012;
        • Conlon R
        • Saheb H
        • Ahmed IIK.
        Glaucoma treatment trends: a review.
        Can J Ophthalmol. 2017;
        • Lewis RA.
        Ab interno approach to the subconjunctival space using a collagen glaucoma stent.
        J Cart Refract Surg. 2014; 40: 1301-1306
        • De Gregorio A
        • Pedrotti E
        • Stevan G
        • Bertoncello A
        • Morselli S.
        XEN glaucoma treatment system in the management of refractory glaucomas: A short review on trial data and potential role in clinical practice.
        Clin Ophthalmol. 2018;
        • Schlenker MB
        • Gulamhusein H
        • Conrad-Hengerer I
        • et al.
        Efficacy, Safety, and Risk Factors for Failure of Standalone Ab Interno Gelatin Microstent Implantation versus Standalone Trabeculectomy.
        Ophthalmology. 2017;
        • Heidinger A
        • Schwab C
        • Lindner E
        • Riedl R
        • Mossböck G.
        A Retrospective Study of 199 Xen45 Stent Implantations From 2014 to 2016.
        J Glaucoma. 2019;
        • Reitsamer H
        • Sng C
        • Vera V
        • et al.
        Two-year results of a multicenter study of the ab interno gelatin implant in medically uncontrolled primary open-angle glaucoma.
        Graefe's Arch Clin Exp Ophthalmol. 2019; 257: 983-996
        • Chen PP
        • Lin SC
        • Junk AK
        • Radhakrishnan S
        • Singh K
        • Chen TC.
        The Effect of Phacoemulsification on Intraocular Pressure in Glaucoma Patients: A Report by the American Academy of Ophthalmology.
        Ophthalmology. 2015; 122: 1294-1307
        • Lochhead J
        • Casson RJ
        • Salmon JF.
        Long term effect on intraocular pressure of phacotrabeculectomy compared to trabeculectomy.
        Br J Ophthalmol. 2003; 87: 850-852
        • Vera VI
        • Horvath C.
        XEN gel stent: The solution designed by AqueSys®.
        Surgical Innovations in Glaucoma. 2014;
        • Shaarawy TM
        • Sherwood MB
        • Grehn F.
        Guidelines on Design and Reporting of Glaucoma Surgical Trials.
        World Glaucoma Association, Amsterdam, The Netherlands2008
        • Widder RA
        • Dietlein TS
        • Dinslage S
        • Kühnrich P
        • Rennings C
        • Rössler G.
        The XEN45 Gel Stent as a minimally invasive procedure in glaucoma surgery: success rates, risk profile, and rates of re-surgery after 261 surgeries.
        Graefe's Arch Clin Exp Ophthalmol. 2018;
        • Karimi A
        • Lindfield D
        • Turnbull A
        • et al.
        A multi-centre interventional case series of 259 ab-interno Xen gel implants for glaucoma, with and without combined cataract surgery.
        Eye. 2019;
        • Hengerer FH
        • Auffarth G
        • Conrad-Hengerer I.
        Comparison of Minimally Invasive XEN45 Gel Stent Implantation in Glaucoma Patients Without and With Prior Interventional Therapies.
        Ophthalmol Ther. 2019;
        • Smith M
        • Charles R
        • Abdel-Hay A
        • et al.
        1-year outcomes of the Xen45 glaucoma implant.
        Eye. 2019;
        • Galal A
        • Bilgic A
        • Eltanamly R
        • Osman A.
        XEN Glaucoma Implant with Mitomycin C 1-Year Follow-Up: Result and Complications.
        J Ophthalmol. 2017;
        • Fea AM
        • Spinetta R
        • Cannizzo PML
        • et al.
        Evaluation of Bleb Morphology and Reduction in IOP and Glaucoma Medication following Implantation of a Novel Gel Stent.
        J Ophthalmol. 2017;
        • Grover DS
        • Flynn WJ
        • Bashford KP
        • et al.
        Performance and Safety of a New Ab Interno Gelatin Stent in Refractory Glaucoma at 12 Months.
        Am J Ophthalmol. 2017; (Aug 4)
        • Tan SZ
        • Walkden A
        • Au L.
        One-year result of XEN45 implant for glaucoma: Efficacy, safety, and postoperative management.
        Eye. 2018;
        • Pérez-Torregrosa VT
        • Olate-Pérez Á
        • Cerdà-Ibáñez M
        • et al.
        Combined phacoemulsification and XEN45 surgery from a temporal approach and 2 incisions.
        2016 (Arch la Soc Española Oftalmol (English Ed)
        • Mansouri K
        • Guidotti J
        • Rao HL
        • et al.
        Prospective Evaluation of Standalone XEN Gel Implant and Combined Phacoemulsification-XEN Gel Implant Surgery: 1-Year Results.
        J Glaucoma. 2018;
        • Donoso R
        • Rodríguez A.
        Combined versus sequential phacotrabeculectomy with intraoperative 5- fluorouracil.
        J Cataract Refract Surg. 2000; 26: 71-74
        • Murthy SK
        • Damji KF
        • Pan Y
        • Hodge WG.
        Trabeculectomy and phacotrabeculectomy, with mitomycin-C, show similar two-year target IOP outcomes.
        Can J Ophthalmol. 2006;
        • Siriwardena D
        • Kotecha A
        • Minassian D
        • Dart JKG
        • Khaw PT.
        Anterior chamber flare after trabeculectomy and after phacoemulsification.
        Br J Ophthalmol. 2000;
        • Lai JSM
        • Tham CCY
        • Chan JCH.
        The clinical outcomes of cataract extraction by phacoemulsification in eyes with primary angle-closure glaucoma (PACG) and co-existing cataract: A prospective case series.
        J Glaucoma. 2006;
        • Wang N
        • Chintala SK
        • Fini ME
        • Schuman JS.
        Ultrasound activates the TM ELAM-1/IL-1/NF-κB response: A potential mechanism for intraocular pressure reduction after phacoemulsification.
        Investig Ophthalmol Vis Sci. 2003;
        • Berdahl J.
        Cataract surgery to lower intraocular pressure.
        Middle East Afr J Ophthalmol. 2009;
        • Samuelson TW
        • Katz LJ
        • Wells JM
        • Duh YJ
        • Giamporcaro JE.
        Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract.
        Ophthalmology. 2011;
        • Francis BA
        • Minckler D
        • Dustin L
        • Kawji S
        • Yeh J
        • Sit A
        • Mosaed S
        • Johnstone M
        • Trabectome Study Group
        Combined cataract extraction and trabeculotomy by the internal approach for coexisting cataract and open-angle glaucoma: initial results.
        J Cataract Refract Surg. 2008 Jul; 34 (PMID: 18571075): 1096-1103
        • Wilkins M
        • Indar A
        • Wormald R.
        Intraoperative Mitomycin C for glaucoma surgery.
        Cochrane Database Syst Rev. 2005;
        • Schiffman J
        • Alward WLM
        • Farrell T
        • et al.
        Three-year follow-up of the Fluorouracil Filtering Surgery Study.
        Am J Ophthalmol. 1993;
        • Cabourne E
        • Clarke JCK
        • Schlottmann PG
        • Evans JR.
        Mitomycin C versus 5-Fluorouracil for wound healing in glaucoma surgery.
        Cochrane Database Syst Rev. 2015;
        • Edmunds B
        • Thompson JR
        • Salmon JF
        • Wormald RP.
        The National Survey of Trabeculectomy. III. Early and late complications.
        Eye. 2002;
        • Szigiato AA
        • Sandhu S
        • Ratnarajan G
        • Dorey MW
        • Ahmed IIK.
        Surgeon perspectives on learning ab-interno gelatin microstent implantation.
        Can J Ophthalmol. 2018;