Human Umbilical Cord Allograft for AGV

 

The Ahmed Glaucoma Valve (AGV) is usually implanted in cases of refractory glaucoma.

While this is an excellent procedure in such cases, the implant has two potential problems. One, there can be a hypertensive phase after a few months of surgery. This is attributed to fibrosis over the plate. Studies report rates ranging between 31%-57%. Another complication is failure of the procedure. It is an immediate postoperative intraocular pressure (IOP) spike that occurs immediately or within six months after surgery. Studies have identified a higher pre-operative IOP and younger age as risk factors for developing a hypertensive phase, which can lead to failure in some eyes. Neovascular glaucoma, higher baseline IOP, and lower visual acuity at the time of presentation have been identified as potential contributors to AGV failure.

EXPOSED AGV

ENCAPSULATED AGV

Several procedures have been suggested to reduce the incidence of hypertensive and failure rates. These include early aqueous suppression, biodegradable collagen matrix, use of a pediatric implant with reduced plate size, amniotic membrane, mitomycin-C, and anterior chamber washout.

However, Rao has reported a new technique involving the implantation of an umbilical cord allograft at the plate site, which may aid in reducing the wound healing response and the IOP outcomes after AGV in refractory glaucoma.

The study involved 34 eyes of 34 patients with refractory glaucoma who underwent AGV with umbilical cord allograft (AmnioPlast THICK™; Life Cell International Private Limited, Mumbai, India) placed over the AGV plate (group 1). They were compared with 30 eyes of 30 patients undergoing AGV without amnioblasts (group 2).

STEPS IN ALLOGRAFT IMPLANTATION

Success was defined as achieving an IOP below 22 mm Hg with or without glaucoma medications. IOP spikes after surgery were identified as a rise in pressure beyond 22 mm Hg at any point beyond six weeks post-surgery following an initial reduction of pressure exceeding 30% from the baseline pre-surgical IOP.

A notable reduction in intraocular pressure (37 ± 7.9 mm Hg preoperative versus 14 ± 3.7 mm Hg at the final follow-up and 28 ± 3.6 mm Hg versus 18 ± 6.7 mm Hg in groups 1 and 2, respectively) was observed in all eyes.

The study found a success rate of 67.8% in the eyes of group 1 and 53.3% in the eyes of group 2 with refractory glaucoma undergoing AGV with a significantly delayed IOP spike in group 1 with the use of umbilical cord allograft.

This shows that umbilical cord allograft is a useful adjunct to AGV implantation to reduce the rates of hypertensive phase and failure rates.

REFERENCE:

Rao A (August 27, 2024) Surgical Outcomes of a Human Umbilical Cord Allograft Over the Ahmed Glaucoma Valve Plate for Refractory Glaucoma. Cureus 16(8): e67923. doi:10.7759/cureus.67923.