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Higher specular cell count density, well-centered graft may decrease DMEK complications
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A higher specular cell count density can improve placement of the corneal graft during Descemet’s membrane endothelial keratoplasty, and a well-centered graft can decrease the rate of complications.
Several factors, including patient age, donor age, patient sex, donor sex and time from death to procurement of the eye, were analyzed in a study of 94 eyes that underwent DMEK at Vance Thompson Vision in Sioux Falls, South Dakota. Postoperatively, 21 eyes required a rebubble procedure and 73 did not.
Of the eyes that needed a rebubble procedure, the only factors that affected the rebubble rate were specular cell count density of the graft and location of the graft. The non-rebubble group had a higher specular cell count density (P = .021) compared with the rebubble group. Also, grafts that were well-centered required less rebubbling (P = .023) when compared with grafts that were centered poorly.
Whether a surgeon decided to let fluid and/or gas out of the anterior chamber after the procedure did not have a correlation with rebubble rates, the researchers wrote.
“This can give options to surgeons who prefer to let gas out of the anterior chamber in favor of lower IOP without necessarily affecting the status of adherence of the graft or the eventual outcome. In addition, this study showed that there was no difference in BCVA between the two groups at 3 months after the initial DMEK procedure, showing that use of a rebubble procedure might not necessarily result in worse outcomes,” they wrote. – by Robert Linnehan
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Jack S. Parker, MD, PhD
The authors point to gross graft decentration and lower-than-ideal endothelial cell densities in the donor tissue as potential causes of postoperative graft detachment. What might be the mechanisms here?
Decentration may be associated with overlap between the graft and the incompletely stripped peripheral rim of host Descemet’s membrane, which some believe interferes with edge attachment. Alternatively, it may be that the curvature of the donor tissue does not “fit” well against the recipient posterior corneal surface if the graft is decentered, and this architectural mismatch is responsible for the poor enduring apposition.
And why would marginally low (but normal) donor ECDs affect graft adherence? Might it be a marker for some diminished capacity to produce an adhesive substance?
All this sounds disappointingly speculative on my part; part of the problem of solving the riddle of graft detachments is that we really do not even know why any grafts ever attach in the first place. For instance, how much help is the gas bubble, really? What other completely overlooked factors are at play? What is the answer that we are all overlooking?
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Mechels KB, et al. Clin Ophthalmol. 2017;doi:10.2147/OPTH.S147217.
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