Clinical trial NCT04454138: Ab Interno Gelatin Stent With Mitomycin C Using Targeted Supra-tenon's Placement
Official title: Ab Interno Gelatin Stent With Mitomycin C Using Targeted Supra-tenon's Placement
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Glaucoma
Lead sponsor: Prism Eye Institute
Sponsor class: OTHER
Collaborators: name: Allergan
First posted: 2020-07-01
Enrollment: 142
Sex: ALL
Minimum age (years): 30
Maximum age (years): 90
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: RETROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Patients aged 30-90 with primary or pigmentary/pseudoexfolliative open angle, primary closed angle, or combined mechanism glaucoma with IOP of 18-40 mmHg on maximum tolerated medical therapy who received a gelatin stent with MMC at Prism Eye Institute from June 2012 to August 2019.

Brief summary: The Xen-45 gelatin microstent is a novel, bleb-forming microinvasive glaucoma surgery (MIGS). Despite demonstrating similar efficacy and safety to trabeculectomy (traditional surgery), the Xen-45 gelatin microstent continues to suffer from occasional surgical failure due to fibrosis of the filtering bleb, and obstruction of the stent. During surgery, placement in a surgery known as supra-tenon's space is believed to maximize aqueous outflow, while preventing obstruction, limiting fibrosis of the bleb, and promoting long-term patency. Despite the theoretical merits, long-term data of outcomes after targeted supra-tenon's placement is needed to fully assess its potential in improving Xen-45 microstent outcomes.

Detailed description: The Xen-45 gelatin microstent (Allergan, Dublin, Ireland) is a novel, bleb-forming microinvasive glaucoma surgery (MIGS). Creation of a filtering bleb through the gel stent and under the conjunctiva lowers intraocular pressure (IOP) by bypassing the natural outflow pathway of aqueous. A recent retrospective cohort study showed comparable safety and risk of failure to trabeculectomy. Amongst the main advantages of this device is the ability to create a bleb without dissecting and disrupting tissue, thus decreasing the amount of wound healing and potentially limiting bleb failure. However, despite demonstrating similar efficacy and safety to trabeculectomy,2 the Xen-45 gelatin microstent continues to suffer from occasional surgical failure due to fibrosis of the filtering bleb, and obstruction of the stent. Although antimetabolites, such as mitomycin C, have decreased reactionary wound healing that can result following surgery, fibrosis may still occur, especially when the components of the Xen-45 gelatin microstent are in close proximity to the fibroblastic structures of tenon's fascia.Tenon's capsule resembles a sponge-like layer with multiple adhesions to the overlying conjunctiva and underlying episclera. Implantation of the XEN within this space creates a higher risk of obstruction and subsequent failure. To ensure the lowest potential for occlusion, bleb scarring, and failure, one must ensure careful placement of the device in the subconjunctival space, avoiding intra-tenon's placement. Placement in the supra-tenon's space is believed to maximize aqueous outflow, while preventing obstruction, limiting fibrosis of the bleb, and promoting long-term patency. Despite the theoretical merits, long-term data of outcomes after targeted supra-tenon's placement is needed to fully assess its potential in improving Xen-45 microstent outcomes.

Eligibility criteria: Inclusion Criteria:

* Patients aged 30-90 with primary or pigmentary/pseudoexfolliative open angle, primary closed angle, or combined mechanism glaucoma with IOP of 18-40 mmHg on maximum tolerated medical therapy who received a gelatin stent with MMC at Prism Eye Institute from June 2012 to August 2019.

Exclusion Criteria:

* Other forms of glaucoma
* Prior incisional glaucoma surgery
* CPC
* Prior corneal graft (PKP, DALK, DSAEK, DMEK).

Primary outcomes:
measure: Postoperative Intraocular Pressure Changes Between Targeted Supratenon's Placement of XEN-45 Gelatin Stent and Nontargeted Placement.
timeFrame: Post op year 1
measure: Postoperative Intraocular Pressure Changes Between Targeted Supratenon's Placement of XEN-45 Gelatin Stent and Nontargeted Placement 2.
timeFrame: Post op Year 1
measure: Postoperative Intraocular Pressure Changes Between Targeted Supratenon's Placement of XEN-45 Gelatin Stent and Nontargeted Placement 3.
timeFrame: Post op year 1
measure: Postoperative Intraocular Pressure Changes Between Targeted Supratenon's Placement of XEN-45 Gelatin Stent and Nontargeted Placement 4.
timeFrame: Post op Year 1
measure: Postoperative Intraocular Pressure Changes Between Targeted Supratenon's Placement of XEN-45 Gelatin Stent and Nontargeted Placement 5.
timeFrame: Post op Year 1
measure: Postoperative Intraocular Pressure Changes Between Targeted Supratenon's Placement of XEN-45 Gelatin Stent and Nontargeted Placement 6.
timeFrame: Post op year 1
Secondary outcomes:
measure: Number of Participants With Postoperative Complications Between Targeted Supratenon's Placement of XEN-45 Gelatin Stent and Non-targeted Placement.
timeFrame: Post op year 1
measure: Number of Participants With Postoperative Interventions Between Targeted Supratenon's Placement of XEN-45 Gelatin Stent and Non-targeted Placement.
timeFrame: Post op year 1
Other outcomes:
Locations:
city: Oakville
country: Canada
facility: Prism Eye Institute
state: Ontario
Study officials:
affiliation: Prism Eye Institute
name: Iqbal Ike Ahmed, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Conlon R, Saheb H, Ahmed II. Glaucoma treatment trends: a review. Can J Ophthalmol. 2017 Feb;52(1):114-124. doi: 10.1016/j.jcjo.2016.07.013. Epub 2016 Nov 17.
citation: Schlenker MB, Gulamhusein H, Conrad-Hengerer I, Somers A, Lenzhofer M, Stalmans I, Reitsamer H, Hengerer FH, Ahmed IIK. Efficacy, Safety, and Risk Factors for Failure of Standalone Ab Interno Gelatin Microstent Implantation versus Standalone Trabeculectomy. Ophthalmology. 2017 Nov;124(11):1579-1588. doi: 10.1016/j.ophtha.2017.05.004. Epub 2017 Jun 7.
citation: Fea AM, Spinetta R, Cannizzo PML, Consolandi G, Lavia C, Aragno V, Germinetti F, Rolle T. Evaluation of Bleb Morphology and Reduction in IOP and Glaucoma Medication following Implantation of a Novel Gel Stent. J Ophthalmol. 2017;2017:9364910. doi: 10.1155/2017/9364910. Epub 2017 Jun 20.
citation: Sng CC, Wang J, Hau S, Htoon HM, Barton K. XEN-45 collagen implant for the treatment of uveitic glaucoma. Clin Exp Ophthalmol. 2018 May;46(4):339-345. doi: 10.1111/ceo.13087. Epub 2017 Nov 29.