Imaging Ahmed Glaucoma Tubes With a Pericardial Graft and Tissue Glue or Partial-Thickness Scleral Flap and Sutures

May 12, 2008 updated by: National University Hospital, Singapore

Anterior Segment Optical Coherence Tomography Findings in Patients With Ahmed Glaucoma Drainage Implants With Either a Pericardial Patch Graft and Fibrin Tissue Glue or a Partial-Thickness Scleral Flap and Conventional Sutures

When implanting an Ahmed glaucoma tube, a scleral flap is usually created to cover the tube, and the conjunctiva is stitched back in place with nylon 10-0 sutures. It is hypothesized that an equally safe or better method is using a bovine pericardial patch graft that can be secured in place over the tube with tissue glue, and using tissue glue to reposition the conjunctiva in place.

Study Overview

Status

Unknown

Conditions

Intervention / Treatment

Detailed Description

Glaucoma drainage devices (GDD) are usually reserved for cases wherein filtration surgery has failed, or for difficult cases that do not respond to filtration surgery, such as neovascular or uveitic glaucoma.

The Ahmed Glaucoma drainage implant (New World Medical, Rancho, Cucamonga,CA) was introduced to the market in 19942. It has a scarab-shaped end plate made of polypropylene (models S2, S3 and B1) or silicone models (FP7, FP8 and FX1). Fenestrations have been added to the end plate of the silicone models. Various sizes of the Ahmed drainage are available, including those with a surface area of 96 mm2 (S3 and FP8) or 184 mm2 (S2 and FP7); while the double-plate version has a surface area of 364mm2 (B1 and FX1). Aqueous humor passes from the anterior chamber through two thin membrane-like elastomer sheets that theoretically restrict flow until a pressure of greater than 8-12 mm Hg is exerted on them.

In the implantation of GDD, absorbable and non-absorbable sutures are used. Sutures are typically used in securing the plate to the sclera, securing the tube to the sclera, suturing a patch graft or scleral flap over the silicone tube, and for conjunctival closure. Post-surgical course can be marked by discomfort, depending on the type of suture used. Absorbable sutures can induce inflammation with localized surface and subconjunctival fibrosis that leads to uneven conjunctival surface and excessive scarring. On the other hand, non-absorbable sutures can erode through tissue post-operatively. Suturing the conjunctiva can cause button-holes and tears, and can be the most time-intensive portion of the surgery.

Fibrin glue has been used in various ophthalmic surgeries such as a sealant for perforated and preperforated corneal ulcers, in mucous membrane grafts, in the management of complicated hypotony and bleb leaks after trabeculectomy, and for preventing immediate postoperative hypotony after glaucoma drainage implant surgery.

In a paper by Kahook and Noecker published in 2006, the authors did a retrospective non-randomized case-control study that reviewed 28 cases of GDD implantations using traditional suture materials compared to 14 consecutive cases of GDD implantation using Tisseel fibrin glue (Baxter AG, Vienna, Austria) for closing the conjunctiva, securing the pericardium patch graft and securing the tube to the sclera. The authors concluded that Tisseel fibrin glue seems to be a safe substitute for some of the sutures used in GDD surgery; and it has no impact on IOP control or complications. It appears to reduce post-operative conjunctival inflammation and time of surgery.

Optical coherence tomography (OCT) is a high-resolution, non-invasive and reproducible imaging technology that was primarily developed to evaluate the retina and retina nerve fiber layer in patients with vitreo-retinal or optic nerve diseases11. Recently, the anterior segment OCT (AS-OCT) has been developed and used to image anterior segment structures. It has also been used to localize the Ex-PRESS miniature glaucoma implant in porcine eyes, while the conventional OCT was used to show the anterior segment findings after non-penetrating deep sclerectomy and the filtering blebs of eyes that underwent glaucoma filtering surgery.

Patients scheduled for Ahmed Tube surgery, with or without lens extraction and intraocular lens implant, will be recruited and randomized into two groups. The first group of patients will have a pericardial patch graft covering the tube, and fibrin glue will be used to attach the graft to the sclera and to close the conjunctiva. The second group will have a partial- thickness scleral flap raised to cover the tube, and the conjunctiva will be closed with conventional sutures.

Study Type

Interventional

Enrollment (Anticipated)

40

Phase

  • Phase 2

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

  • Singapore
      • Singapore, Singapore, 119074
        • Recruiting
        • National University Hospital
        • Sub-Investigator:
          • Grace Dizon, MD
        • Sub-Investigator:
          • Jovina See, MMed,FRCS
        • Sub-Investigator:
          • Cecilia Aquino, MD

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

41 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • More than 40 years old
  • Able to give informed consent
  • Diagnosis of any type of glaucoma needing a Glaucoma drainage device (Ahmed tube implant) with or without lens extraction and intraocular lens implant because of uncontrolled intraocular pressures inspite of maximum tolerated medical therapy

Exclusion Criteria:

  • Inability to give informed consent
  • History of ocular infection or inflammation in the past two months

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: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Intraocular pressure
Anterior segment optical coherence tomography appearance and measurements of the overlying conjunctiva, areas above and beneath the pericardial patch graft or partial thickness scleral flap, anterior chamber depth

Collaborators and Investigators

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

Sponsor

National University Hospital, Singapore

Investigators

  • Principal Investigator: Paul Chew, FRCSEd,MMed, National University Hospital, Singapore

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

February 1, 2007

Study Completion (Anticipated)

March 1, 2008

Study Registration Dates

First Submitted

March 27, 2007

First Submitted That Met QC Criteria

March 27, 2007

First Posted (Estimate)

March 28, 2007

Study Record Updates

Last Update Posted (Estimate)

May 14, 2008

Last Update Submitted That Met QC Criteria

May 12, 2008

Last Verified

May 1, 2008

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • DSRB A/06/375

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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