Glaucoma drainage devices (GDDs) have widely 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 has to be covered by a patch graft made of donor sclera or pericardium. However, such a patch graft still carries a high rate of progressive thinning and erosion, a complication that we speculate is resulted from the lack of cellular infiltration from the surrounding host conjunctival stroma, thus leading to poor integration of these patch grafts to the host tissue. We further speculate that a thicker version of cryopreserved amniotic membrane (AM) could offer better tensile strength, suitable for tectonic support, and biologically active to promote cellular infiltration by the surrounding host conjunctival stroma, thus ameliorating the patch graft thinning/erosion. This hypothesis is supported by our preliminary studies showing that a thicker AM, termed AmnioGraft(R)-G (AG-G), has successfully been developed, that AG- G can be used to cover the GDD tube during the primary implantation, and that anterior segment optical coherence tomography (OCT) can be used to monitor host cell interaction with the transplanted AG-G. In this Phase I application, we will demonstrate the short-term (6 months) efficacy of AG-G for covering the tube in primary GDD surgery (Aim 1), and confirm the host cell integration into AG-G, but not pericardium, using OCT after transplantation over the GDD tube (Aim 2). Accomplishment of the above two Aims will allow us to collect adequate short-term stability/efficacy data to better design a prospective controlled study in the Phase II application to assess long term clinical efficacy of using AG-G to secure GDD tube and its overall superiority over sclera or pericardium in preventing tube exposure, providing a better esthetic appearance, being less likely to cause corneal dellen due to less conjunctival elevation, and allowing laser suture lysis needed to treat postoperative hypertensive phase. The new knowledge of how AM may modulate wound healing in the subconjuntival space will allow us in Phase II investigate whether it can also be considered as a graft to augment the success of trabeculectomy with mitomycin C in high risk refractory glaucoma.
Our study will demonstrate that a thicker AM, termed AmnioGraft(R)-G (AG-G), could be used to cover the glaucoma drainage device (GDD) tube during the primary implantation in cases with complicated glaucoma, and confirm its overall superiority over existing patches in offering better tensile strength suitable for tectonic support and preventing tube exposure to improve the surgical outcome and prevent complications in high risk glaucoma patients.
| Anand, Aashish; Sheha, Hosam; Teng, Christopher C et al. (2011) Use of amniotic membrane graft in glaucoma shunt surgery. Ophthalmic Surg Lasers Imaging 42:184-9 |
