Keratometric Change After XEN, Trabeculectomy and Tube Shunts (Topo-XEN)

February 14, 2023 updated by: Centre hospitalier de l'Université de Montréal (CHUM)

Comparison of Keratometric Change After Xen Gel Stent Implantation, Trabeculectomy, and Tube Shunts

The main goal of this study is to assess the severity of postoperative corneal astigmatism induced by implantation of the XEN Gel Stent compared to that induced by traditional filtering surgery (trabeculectomy and GDDs). Corneal astigmatism can be assessed using corneal topography, a non-invasive tool which provides an accurate estimate of corneal curvature in all meridians. To the best of our knowledge, no study has yet attempted to quantify the amount of astigmatism induced by the XEN Gel Stent.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Following glaucoma surgery, patients often experience decreased visual acuity (VA) which can partly be explained by induced changes to the optical properties of the cornea. Corneal astigmatism can be assessed using corneal topography, a non-invasive tool which provides an accurate estimate of corneal curvature in all meridians. Obtained keratometric measures (termed K values) can allow clinicians to quantify the amount of astigmatism before and after surgical intervention.

Multiple studies have been previously published to evaluate induced postoperative astigmatism after trabeculectomy. However, only two studies have characterized the impact of GDDs on keratometric values. To the best of our knowledge, no study has yet attempted to quantify the amount of astigmatism induced by the XEN Gel Stent.

Assessing the impact of the XEN implant on corneal astigmatism is important to better characterize the expected course of postoperative visual rehabilitation, the impact of novel glaucoma devices on corneal properties and the predictability of refractive outcomes after XEN implantation. Compared to traditional filtering surgery, the XEN Gel Stent is inserted without opening the conjunctiva and is implanted further from the corneal limbus (5 mm). These factors may allow for a reduced amount of surgically induced corneal astigmatism.

We hypothesize that the XEN Gel Stent implantation induces less corneal astigmatism compared to traditional filtering surgery, such as the trabeculectomy and GDDs (BGI or AGV).

The main goal of this prospective interventional comparative study is to assess the severity of postoperative corneal astigmatism induced by implantation of the XEN Gel Stent compared to that induced by traditional filtering surgery (trabeculectomy and GDDs).

Secondary objectives are evaluation of visual acuity recovery as well as IOP reduction and other parameters between groups.

Glaucoma surgery (XEN Gel Stent, trabeculectomy or GDD implantation) will be performed by the ophthalmologists in charge of the study according to standard procedures. For each patient, the most appropriate type of glaucoma surgery will be recommended by the ophthalmologist regardless of patients' participation in the study, as dictated by the specific nature of their glaucoma and following current standards of care.

Study Type

Interventional

Enrollment (Anticipated)

90

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Quebec
      • Montreal, Quebec, Canada, H2X 3E4
        • Recruiting
        • Centre hospitalier de l'Université de Montréal (CHUM)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Eyes with an IOP above target and/or progressing on maximally tolerated medical therapy;
  • Patients aged 18 years or older;
  • Ability to provide informed consent;
  • Ability to be followed for the entire duration of the study.

Exclusion Criteria:

  • Patients less than 18 years old;
  • Inability to provide informed consent;
  • Inability to be followed for the entire duration of the study;
  • Patients undergoing surgery combined with cataract extraction;
  • Presence of severe dry eye disease;
  • Presence of ocular comorbidities other than glaucoma, such as corneal or retinal disease.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Factorial Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: XEN Gel Stent implantation
Participants suffering from glaucoma who are candidates for XEN Gel Stent implantation
Diagnostic test: Corneal topography: OPD-Scan
Corneal topography photography, taken by specular reflection (OPD-Scan) by measuring corneal curvature, thickness and topography.
Diagnostic test: Corneal topography: Pentacam
Corneal topography photography, taken by Scheimpflug imaging (Pentacam) by measuring corneal curvature, thickness and topography.
Experimental: Trabeculectomy
Participants suffering from glaucoma who are candidates for trabeculectomy
Diagnostic test: Corneal topography: OPD-Scan
Corneal topography photography, taken by specular reflection (OPD-Scan) by measuring corneal curvature, thickness and topography.
Diagnostic test: Corneal topography: Pentacam
Corneal topography photography, taken by Scheimpflug imaging (Pentacam) by measuring corneal curvature, thickness and topography.
Experimental: GDD implantation
Participants suffering from glaucoma who are candidates for GDD implantation (BGI or AGV)
Diagnostic test: Corneal topography: OPD-Scan
Corneal topography photography, taken by specular reflection (OPD-Scan) by measuring corneal curvature, thickness and topography.
Diagnostic test: Corneal topography: Pentacam
Corneal topography photography, taken by Scheimpflug imaging (Pentacam) by measuring corneal curvature, thickness and topography.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Keratometric values (OPD-Scan)
Time Frame: Baseline, 2 months, 6 months, 12 months
Change in simulated keratometric (K) values obtained by OPD-Scan between the indicated timepoints.
Baseline, 2 months, 6 months, 12 months
Keratometric values (Pentacam)
Time Frame: Baseline, 2 months, 6 months, 12 months
Change in simulated keratometric (K) values obtained by Pentacam between the indicated timepoints.
Baseline, 2 months, 6 months, 12 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Best-corrected visual acuity change
Time Frame: Baseline, 2 months, 6 months, 12 months
Evaluation of visual acuity change, measured using the Snellen chart.
Baseline, 2 months, 6 months, 12 months
Intraocular pressure change
Time Frame: Baseline, 2 months, 6 months, 12 months
Evaluation of intraocular pressure control, measured using gold standard Goldmann applanation tonometry.
Baseline, 2 months, 6 months, 12 months
Visual field change change
Time Frame: Baseline, 6 months, 12 months
Evaluation of visual field change. Visual field change will be calculated using the mean deviation (MD) values and pattern standard deviation (PSD) values measured using automated Humphrey 24-2 perimetry.
Baseline, 6 months, 12 months
Retinal nerve fiber layer thickness change
Time Frame: Baseline, 6 months, 12 months
Evaluation of retinal nerve fiber layer (RNFL) thickness change (µm), using the average RNFL thickness values measured using Spectral Domain Optical Coherence Tomography (SD-OCT). The change in thickness (µm) will be calculated between the time points described.
Baseline, 6 months, 12 months
Ganglion cell layer thickness change
Time Frame: Baseline, 6 months, 12 months
Evaluation of ganglion cell layer (GCL+) thickness. This GCL+ thickness is measured using the values for the average ganglion cell layer and inner plexiform layer thickness of the retina (value called "Average GCL + IPL thickness") obtained by Spectral Domain Optical Coherence Tomography (SD-OCT). The change in thickness (µm) will be calculated between the time points described.
Baseline, 6 months, 12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Centre hospitalier de l'Université de Montréal (CHUM)

Collaborators

Allergan

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 4, 2020

Primary Completion (Anticipated)

January 1, 2025

Study Completion (Anticipated)

December 1, 2025

Study Registration Dates

First Submitted

October 21, 2020

First Submitted That Met QC Criteria

October 21, 2020

First Posted (Actual)

October 26, 2020

Study Record Updates

Last Update Posted (Actual)

February 15, 2023

Last Update Submitted That Met QC Criteria

February 14, 2023

Last Verified

February 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 20.240

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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