Question of which technique is superior remains unanswered amid shift to thinner grafts
‘Nano-thin’ grafts have recently begun to be used for DSAEK. Long-term data are needed to see how the outcomes of this technique compare with DMEK.
Reviewed by Clara C. Chan, MD
Corresponding with the evolution in techniques for endothelial keratoplasty (EK), there has been a debate over which procedure corneal surgeons should perform. Going forward, the discussion will be about the battle between Descemet’s membrane endothelial keratoplasty (DMEK) and nano-thin Descemet’s stripping automated endothelial keratoplasty (NT-DSAEK), said Clara C. Chan, MD.
Dr. Chan is medical director, The Eye Bank of Canada (Ontario Division), and assistant professor of ophthalmology and vision sciences, University of Toronto, Toronto, Ontario.
“Surgeons performing DSAEK first migrated to ultrathin (UT) DSAEK, and now we will see migration to NT-DSAEK,” Dr. Chan said. “The use of thinner graft tissue has benefits of a lower rejection rate, more predictable tissue handling, fewer detachments, and lower rebubbling rates.”
“We know that, when compared with DSAEK using thicker grafts, DMEK seems to be associated with lower higher-order aberrations (HOAs) and faster visual recovery,” she said. “Studies are needed to compare long-term outcomes of DMEK with UT- and NT-DSAEK.”
Dr. Chan reviewed published literature comparing outcomes with different EK techniques. She cited the 2008 American Academy of Ophthalmology (AAO) Ophthalmic Technology Assessment report on Descemet’s stripping endothelial keratoplasty (DSEK), noting that the first outcomes study on DSEK appeared in the peer-reviewed literature in 2005.
In 2006, the first report of DMEK appeared in the peer-reviewed literature. Thin DSAEK, using a graft with a thickness <100Î¼m was described in 2011, and the first randomly selected controlled trial comparing DMEK and UT-DSAEK (average central graft thickness 73 microns) was reported this year. Patients included in the study had Fuch’s endothelial dystrophy or pseudophakic bullous keratopathy and were followed for 12 months after surgery.
RELATED: When To Consider Surgery For PtosisThe study found DMEK was associated with better BSCVA at three, six, and 12 months, but also that later during the available follow-up, there was a trend for increased endothelial cell loss after DMEK compared with UT-DSAEK. There were no statistically significant differences between the two surgeries in rates of rebubbling, graft rejection or graft survival, although the study only included 50 eyes, and may have been underpowered to evaluate these outcomes.
Analyses of posterior corneal HOAs showed a decrease from baseline in eyes that underwent DMEK, and an increase in the UT-DSAEK group. Total posterior corneal HOAs at six and 12 months were shown to correlate with better BSCVA outcomes in DMEK, consistent with previous reports, Dr. Chan said.
The only published comparison of NT-DSAEK and DMEK is a prospective case series that includes 28 eyes with Fuch’s endothelial dystrophy. The surgeons evaluated BSCVA as the primary outcome and found it was better after DMEK at one month postoperatively, but similar for the two procedures at three, six, and 12 months.
In addition, the percentage of eyes achieving BSCVA of 20/25 or better was similar in the two groups at six and 12 months. Rebubbling was needed in one eye that had NTDSAEK. There were no cases of graft rejection or failure.
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Clara C. Chan, MD
This article was adapted from Dr. Chan’s presentation during the 2019 meeting of the American Society of Cataract and Refractive Surgery. Dr. Chan has no disclosures.