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Injecting air into the lumen of the graft is an effective and efficient technique for dealing with the dreaded "taquito" graft configuration when performing Descemet's membrane endothelial keratoplasty (DMEK), said Neda Shamie, MD.
Injecting air into the lumen of the graft is an effective and efficient technique for dealing with the dreaded “taquito” graft configuration when performing Descemet’s membrane endothelial keratoplasty (DMEK), said Neda Shamie, MD.
Speaking at the 2018 ASCRS Cornea Day, Dr. Shamie and the session panel discussed strategies for DMEK graft unfolding, including when faced with the challenging situation of DMEK in myopic eyes.
“We can all agree that DMEK has a tough learning curve but once that has been passed, DMEK is an elegant and beautiful surgery,” said Dr. Shamie, associate professor of ophthalmology, USC Keck School of Medicine, and director, USC Doheny Eye Center, Los Angeles. “One of the challenges with DMEK, however, is that it is not always predictable, and you have to be prepared to manage whatever you face.”
Rather than spending time with tapping and other manipulations, Dr. Shamie said she goes immediately to placing an air bubble inside the lumen of the taquito graft, working in a shallow chamber. After the graft unrolls and is positioned, the overlying air bubble is removed and another is injected under the graft to hold the tissue in place.
“The air behaves like an extra finger in the eye that opens the folds,” she explained.
Dr. Shamie said she “does a happy dance” when the DMEK graft is configured with double rolls like an “old paper map scroll.”
Before opening the graft, however, she first centers it by using digital compression to modulate the anterior chamber. Once centered, the double-scrolled graft can be easily opened just by tapping gently on the surface of the cornea.
“Waiting to open the graft until after it is centered is key,” she said. “It is much easier to center the graft while the edges are still scrolled, whereas it can be almost impossible to move the graft after it is already open.”
Similar manipulations are done for a graft that is configured like a “burrito fold.”
Dr. Shamie said she combines tapping and nudging maneuvers, modulating the chamber by trying to deepen it where she wants the graft to unfold and shallowing it where she wants the tissue to stay put.
The challenge is greater if the graft presents as a “carpet roll,” rolled over on itself from one end only with an open opposite end.
Dr. Shamie said that in this situation, she wants the anterior chamber to be as shallow as possible and the pupil constricted. To enable unrolling for this type of configuration, she attempts to hold the open edge of the graft in place by pressing down at the pars plana and on the surface of the cornea.
“I am not really jamming it down,” she said. “Rather, I am just trying to shallow the chamber.”
If the graft injects upside down, a fluid wave is used to get the tissue to reverse its orientation. Angling fluid in a downward direction can encourage the graft to flip around, Dr. Shamie said.
Graft unfolding becomes more challenging when working in a myopic eye with a deeper anterior chamber. Members of the panel agreed that beginning DMEK surgeons might do best to avoid myopic eyes for their initial cases.
Shallowing the chamber by removing fluid is something to consider when trying to get a taquito graft to unfold in an eye with a deeper anterior chamber. Surgeons should be careful with tapping and shallowing in deeper eyes, however, because these maneuvers can release iris pigment.
Retinal detachment is another potential concern when doing decompression in a myopic eye, Dr. Shamie said.