FORT LAUDERDALE, Florida — For patients undergoing glaucoma drainage implant surgery, patch grafts from amniotic membranes and umbilical cords (AmnioGuard, Bio-Tissue) are as safe and effective for covering the implant tubes as the long-established pericardium patch grafts (Tutoplast, IOP Ophthalmics).
They also provide better translucence and cosmetic appearance, according to investigators from the Shunt Tube Exposure Prevention Study.
"Shunt tubes need to be covered with a patch graft to prevent exposure and infection of the tube, which can have debilitating consequences," Mohammed Sayed, MD, from the Bascom Palmer Eye Institute at the Miami Miller School of Medicine, said here at the American Glaucoma Society 2016 Annual Meeting
"Many materials have been used as patch grafts, and some of them, including donor sclera and pericardium, have been used for years, but tube exposure is often reported with these grafts," he told Medscape Medical News.
In their phase 2 study, Dr Sayed and his group used anterior-segment optical coherence tomography to compare exposure rate and integration with recipient tissue for the two types of patch grafts.
Of the 48 eyes that underwent glaucoma drainage implant surgery with a Baerveldt device, 25 were randomly assigned to receive AmnioGuard and 23 to receive Tutoplast. Mean follow-up was 10 months (range, 1 - 19 months).
"We had great results. We found that the amniotic membranes integrate better with the host tissues, as demonstrated by anterior-segment optical coherence tomography," he said.
In the pericardium group, tube exposure occurred in two (8.7%) eyes — the first 2 months after surgery and the second 6 months after surgery.
In the amniotic membrane group, there was no tube erosion or exposure. There was one complication — persistent hypotony — but it was unrelated to the patch graft. In that patient, the tube was repositioned and tied, and the patch graft was replaced with a corneal patch graft, Dr Sayed explained.
"There was no evidence of immunologic reaction, inflammation, or infection with either graft," he reported.
The grafts derived from amniotic membrane and umbilical cords offer an advantage in addition to better host-tissue integration, he pointed out.
"They give a better cosmetic result because they are more transparent. Sometimes patients complain that a white spot is visible on their eye from the other type of patch graft, but because this material is not visible, there are no white spots," Dr Sayed said.
Tube Exposure a Problem
"Exposure or erosion of tubes is definitely a problem we see after the insertion of a tube, whether it's a Baerveldt or an Ahmed," said Shuchi Patel, MD, from the West Palm Beach Veterans Administration Hospital in Florida.
"The pericardium patch graft is usually thick and white, and leaves this noticeable white spot, while this amniotic membrane patch is clear, so it is just cosmetically more appealing," Dr Patel told Medscape Medical News. "If it is obviously not dissolving or thinning, you will have less erosion as well, and it has been found to be biocompatible."
These findings are timely because of concern that there will be less, or no, reimbursement for the Tutoplast, the graft commonly used to cover the tubes.
"This study might help get reimbursement back by showing that there is something even better than what is currently available" and that it is a necessary part of the surgery, she said. "That's important, not just clinically but also financially."
The study was sponsored by the National Eye Institute of the National Institutes of Health. Dr Sayed and Dr Patel have disclosed no relevant financial relationships.
American Glaucoma Society (AGS) 2016 Annual Meeting: Abstract 42. Presented March 3, 2016.
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Cite this: Amniotic Patch for Glaucoma Safe and Imperceptible - Medscape - Mar 09, 2016.