Shunt Tube Exposure Prevention Study (STEPS)

Amniotic Membrane Versus Pericardium in Reducing Glaucoma Drainage Tube Exposure: A Randomized Clinical Trial

National Eye Institute (NEI), Bascom Palmer Eye Institute, The New York Eye & Ear Infirmary, Columbia University

This is a multi-site randomized clinical trial to evaluate the long-term efficacy of the thicker amniotic membrane graft (AmnioGuard™, Bio-Tissue, Inc, Miami, FL) in reducing shunt tube exposure in patients undergoing glaucoma drainage device implantation.

Glaucoma drainage devices (GDDs) have been used in the treatment of high-risk refractory glaucoma. To avoid tube exposure, which may lead to serious eye infection, the implanted GDD tube must be covered by a patch graft, traditionally made of either donor sclera or pericardium. However, these patch grafts still carry a high rate of progressive thinning and erosion, a complication that the investigators speculate results from the lack of cellular infiltration from the surrounding host conjunctival stroma and poor integration of these patch grafts to the host tissue. The investigators further speculate that a thicker version of cryo-preserved amniotic membrane (AM), manufactured by Bio-Tissue, Inc.,could offer better tensile strength, be suitable for tectonic support, and have biological activities to promote cellular infiltration by the surrounding host conjunctival stroma, thus reducing progressive allogeneic patch graft thinning/erosion. Through SBIR Phase I grant support (R43 EY19785), the investigators have evaluated the thicker AM as an alternative patch graft for covering the GDD tube during the primary implantation. The investigators further monitored the host cell interaction using anterior segment optical coherence tomography (OCT). The investigators have successfully accomplished the proposed aims of the above studies, which demonstrated the short-term stability/efficacy of AM in covering the tube in primary GDD surgery (Phase I-Aim 1) and confirmed the feasibility of using OCT to distinguish host cell infiltration into the AM after transplantation over the GDD tube (Phase I-Aim 2). In this SBIR Phase II, the investigators propose to conduct a prospective, controlled study to compare the long-term safety and efficacy of the thicker AM (AmnioGuard™, Bio-Tissue, Inc, Miami, FL) to the pericardium (Tutoplast®, IOP Inc, Costa Mesa, CA) in securing the GDD tube and reducing tube exposure and graft thinning in patients with high risk glaucoma. The investigators will also study the risk factors that may contribute to GDD tube exposure. Accomplishment of this Phase II study will position AM as an effective alternative to the existing patch grafts to reduce tube exposure and enhance the success of GDD implantation, while providing a better aesthetic appearance and allowing visualization of the tube in patients with high risk glaucoma. The investigators speculate that such a graft might also have other clinical applications outside of covering GDD tubes.

After GDD implantation, amniotic membrane graft (AmnioGuard™, Bio-Tissue inc, Miami, FL) is used to cover the GDD tube.

After GDD implantation, a pericardial graft (Tutoplast®, IOP Inc, Costa Mesa, CA) is used to cover the GDD tube.

The surgery includes conjunctival incision, placement and securing the GDD plate in one quadrant, paracentesis and tube insertion into the anterior chamber, tube fixation to the episclera.

For subjects assigned to the treatment group, Amnioguard is used to cover the shunt tube. The conjunctiva is then closed.

For subjects assigned to the control group Tutoplast is used to cover the tube. The conjunctiva is then closed.

Impending conjunctival erosion can be indicated by loss of conjunctival capillaries over the tube, usually 1 to 3 mm from the corneoscleral junction. Definitive tube exposure is accompanied by conjunctival tissue loss, graft melting.

GDD Failure, based on reoperation to control the IOP, and also include the defined by the following criteria: (1) IOP ≥21 mm Hg or not reduced by 30% below baseline on two consecutive follow-up visits after 3 months. (2) IOP ≤5 mm Hg on two consecutive follow-up visits after 3 months. (3) Additional glaucoma surgery. (4) Loss of light perception vision.

Inclusion Criteria: Patients with uncontrolled glaucoma undergoing GDD implantation and carry one of the following two strata of high risk factors: Primary open angle glaucoma with previous conjunctival cutting surgery including prior failed trabeculectomy. Secondary glaucoma, e.g., neovascular, uveitic, or post-traumatic glaucoma. Age range: 21- 80 years old. Both genders and all ethnic groups comparable with the local community. Patients able and willing to cooperate with investigational plan. Patients able and willing to complete postoperative follow-up. Patients able to understand and willing to sign a written informed consent. Exclusion Criteria: Ocular infection within 14 days prior to prior to study entry. No light perception vision Previous cyclodestructive procedure. Children under 21 (see Inclusion of Children). Active drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements. Inability or unwillingness of subject or legal guardian/representative to give written informed consent.

Anand A, Sheha H, Teng CC, Liebmann JM, Ritch R, Tello C. Use of amniotic membrane graft in glaucoma shunt surgery. Ophthalmic Surg Lasers Imaging. 2011 May-Jun;42(3):184-9. doi: 10.3928/15428877-20110426-01.