May 2019

CORNEA

Research Highlight
What’s new in corneal transplantation


by Maxine Lipner EyeWorld Senior Contributing Writer

Corneal transplant techniques continue to evolve. In a recent study,1 University of Toronto investigators examined the types of transplant surgeries performed and found that partial thickness transplants accounted for 85% of all of their current graft procedures, according to Neeru Gupta, MD. This was up from about 65% a few years earlier.
The study initially looked at 2012 when the University of Toronto centralized all of the corneal transplants, which had been at multiple teaching hospitals, into a single center at the Kensington Eye Institute. The idea was to look at current indications and approaches to corneal transplantation during the first year. “This was at a time when partial thicknesses were taking off,” Dr. Gupta said. “We found that a failed graft was the most common indication for full thickness transplant but that partial thickness accounted for two-thirds of all procedures.”2
A few years later, investigators decided to take another look and see where procedures stood. The investigation considered the period from January 2014 to December 2016, Dr. Gupta said. “When we looked at the initial 2012 to 2013 data, we found that the number one partial thickness procedure was DSAEK,” she said. “But when we did the new study, we found that DMEK had emerged as the procedure of choice.” This was something investigators weren’t expecting because technically it’s more challenging. “But the studies have reported better visual outcomes with DMEK compared to DSAEK, with lower rates of graft rejection,” Dr. Gupta said. “We need to watch to see whether longitudinally this has any impact on the long-term graft failure.”
Investigators also found that the leading indication for full thickness procedures continues to be a failed graft, Dr. Gupta reported. Still, partial thickness procedures, which had accounted for about two-thirds of those in the initial study, in a short period of time were up to 85%. She said this could be attributed to improved visual outcomes, reduced astigmatism, and possibly fewer suture complications compared to penetrating keratoplasty. Dr. Gupta also credits surgeons’ growing experience with DMEK, which was new to many in 2013, with practitioners at the time facing a learning curve with the rapid growth of the procedure.
DSAEK’s popularity held in bullous keratopathy cases. “This has been shown to have less endothelial cell loss post-transplant,” Dr. Gupta said, adding that while such bullous keratopathy cases are still mainly treated by DSAEK, DMEK is gaining ground.
Results showed that the most common cause for corneal transplant was Fuchs’ dystrophy, which accounted for 42% of the transplants performed, with graft failure at 17%, and bullous keratopathy and keratoconus both at 15%.
In Dr. Gupta’s view, corneal transplantation has changed a lot. “Compared to a decade ago, there has been a huge shift,” she said. “In just the last 5 years, partial thickness has dominated compared to PKP, and although DSAEK was the procedure of choice for our most common pathologies, it’s now DMEK at the University of Toronto.”
While many surgeons already favor this, there is opportunity for further growth, she pointed out. Use of precut donor tissue may be one such avenue. “If you remove the time that it takes for DMEK, in terms of OR time when you’re preparing corneal tissue and it’s ready to go, that’s a huge improvement and will help to increase adoption.”
Going forward, Dr. Gupta thinks more studies are needed to help determine whether new complications or changing impact on graft survival are going to emerge as a result of doing more DMEK. “I think another study similar to this in a few years will help give us some of the longitudinal data to understand whether the observed patterns have changed the outcomes,” she said.

About the doctor

Neeru Gupta, MD, PhD
Professor and Dorothy Pitts Chair,
Departments of Ophthalmology & Vision Sciences and Laboratory Medicine and Pathobiology
Professor, Dalla Lana School of Public Health University of Toronto

References

1. Chan SWS, et al. New trends in corneal transplants at the University of Toronto. Can J Ophthalmol. 2018;53:580–587.
2. Le R, et al. Current indications and surgical approaches to corneal transplants at the University of Toronto: A clinical-pathological study. Can J Ophthalmol. 2017; 52:74–79.

Financial interests

Gupta
: Allergan

Contact information

Gupta: GUPTAN@smh.ca

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