March 2020

CORNEA

Skill focus
Endothelial transplants on the cutting edge


by Maxine Lipner Senior Contributing Writer


What was once considered very thin for DSAEK at 100 μm is now surpassed by nanothin DSAEK with tissue of 50 μm or less.
Source: Edward Holland, MD

DMEK tissue, such as that pictured above, can be more difficult to prepare.
Source: David Vroman, MD

 

Endothelial transplants continue to evolve, with DSAEK grafts getting thinner and a new, graft-free option, Descemet’s stripping only (DSO), beginning to emerge. EyeWorld spoke with experts about the latest techniques as well as tried and true procedures.
“The current standard of care remains DSAEK by numbers, although DMEK is probably going to become the predominant procedure in the next couple of years because it is growing so quickly,” said Mark A. Terry, MD. With DSAEK results improving, the decision of which procedure to perform comes down to whether the better vision with DMEK is worth the technique’s increased risk of graft failure in complex cases, he said.
Dr. Terry thinks that in routine cases, like Fuchs dystrophy, DMEK is the best option, due to faster visual rehabilitation and better quality of vision. But in more challenging cases, such as aphakia or in the presence of an anterior chamber lens, DMEK risk is greater. “If the surgical risk does not warrant the benefit, you should go with the safer procedure,” Dr. Terry said.

Considering thin DSAEK

Historically, “standard” DSAEK grafts were 150 µm. In 2009, Edward Holland, MD, postulated that thinner DSAEK grafts resulted in better visual acuity and called DSAEK grafts that were 135 µm or less “thin DSAEK.” Massimo Busin, MD, developed a technique that resulted in DSAEK grafts becoming less than 100 µm and proposed the term “ultrathin DSAEK.” Dr. Holland and colleagues developed a technique that resulted in the thinnest grafts to date, “nanothin DSAEK,” with the grafts 50 µm or less. A study comparing the nanothin DSAEK technique to DMEK had promising results.1 “We found that at 1 month the DMEK patients saw better than the nanothin grafts, but at 3, 6, and 12 months, the visual acuity was the same with both techniques,” Dr. Holland said.
While nanothin DSAEK might cause a slight delay in visual recovery, the graft is easier to handle and unfold, and the detachment rate is lower than DMEK, Dr. Holland said. While DMEK is his preferred procedure for the majority of patients, if graft detachment is more likely or if the patient doesn’t have 20/20 potential, Dr. Holland favors nanothin DSAEK over DMEK because of the lower complication rate.
“About 20% of my patients are at a higher risk for graft detachment, and I can offer them a DSAEK procedure that has a lower graft detachment rate and is easier to perform, and I’m not sacrificing vision,” Dr. Holland said.
However, when it comes to reviving a failing penetrating keratoplasty graft, in most instances Dr. Holland still performs DMEK, reserving the nanothin approach for about 20% of complex or detachment-prone cases.
Dr. Terry, who uses the ultrathin DSAEK approach, always does DMEK on a failing PKP, unless the patient has had a prior pars plana vitrectomy. Dr. Terry chooses ultrathin DSAEK for complex eyes with previous pars plana vitrectomies, aphakia or anterior chamber IOLs.

Choosing DSO

DSO involves removing the central 4 mm of Descemet’s membrane. From there the patient’s own cells are used to “rejuvenate” the area, with no graft necessary, explained Deepinder K. Dhaliwal, MD. “We don’t know if the endothelial cells are actually dividing and proliferating or just migrating,” she said, adding that patients are often motivated by this option to avoid a graft.
Dr. Terry reserves DSO for Fuchs patients who have confluent guttata in the central 4–5 mm of cornea. Dr. Dhaliwal recommended only selecting patients who have functional vision in their fellow eye, citing prolonged visual recovery, even in rapid responders. Visual recovery can take 3–4 weeks. “The person has to be well educated [on the procedure] and very patient,” she said, explaining that vision on the first day post-DSO is like a “whiteout” from corneal edema. She also requires that patients have a peripheral endothelial cell count of more than 1,000 mm2.
In a study, Dr. Dhaliwal and co-investigators found that 20/40 vision was attained 7.2 weeks after DSO vs. 2.2 weeks for DMEK.2 However, a benefit of DSO is avoiding the graft and immunosuppression. Dr. Dhaliwal does recommend using a rho kinase inhibitor 4 times a day for 6–8 weeks to help stimulate the peripheral endothelium.
In DSO cases where the cornea does not clear after 6 weeks, Dr. Terry performs a “rescue” DMEK procedure to avoid corneal haze.
Dr. Terry views this as a transformative time for endothelial transplant procedures. “The advances in treating endothelial failure have never been more exciting than they are right now,” he concluded.

About the doctors

Deepinder K. Dhaliwal, MD
Professor of ophthalmology
University of Pittsburgh
School of Medicine
Pittsburgh, Pennsylvania

Edward Holland, MD
Professor of ophthalmology
University of Cincinnati
Cincinnati, Ohio

Mark A. Terry, MD
Director of Corneal Services
Devers Eye Institute
Portland, Oregon

References

1. Kurji KH, et al. Comparison of visual acuity outcomes between nanothin Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty. Cornea. 2018;37:1226–1231.
2. Huang MJ, et al. Descemetorhexis without endothelial keratoplasty versus DMEK for treatment of Fuchs endothelial corneal dystrophy. Cornea. 2018;37:1479–1483.

Relevant disclosures

Dhaliwal
: CorneaGen, Trefoil
Holland: CorneaGen, Minnesota Lions Eye Bank
Terry: None

Contact

Dhaliwal: dhaliwaldk@upmc.edu
Holland: eholland@holprovision.com
Terry: MTerry@deverseye.org

Endothelial transplants on the cutting edge Endothelial transplants on the cutting edge
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