Shunt Tube Exposure Prevention Study

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.

Inclusion Criteria:

- Patients with uncontrolled glaucoma undergoing GDD implantation and carry one of the
following two strata of high risk factors:

1. Primary open angle glaucoma with previous conjunctival cutting surgery including
prior failed trabeculectomy.

2. 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.