January 2018

COVER FEATURE

All you need to know about cornea transplants
New trends in endothelial keratoplasty


by Rich Daly EyeWorld Contributing Writer


DMEK patient at 1 day postop

Same DMEK patient at 1 week postop, when 20/25 vision had been achieved
Source: Sophie Deng, MD

Surgeons explore whether DSAEK is still better for certain patients and other lingering questions

Surgeons have found

that the keys to selecting newer corneal transplant procedures involve a solid understanding of techniques, patient selection, and communication.
Sophie Deng, MD, professor of ophthalmology, cornea division, University of California, Los Angeles, has found Descemet’s stripping automated endothelial keratoplasty (DSAEK) is a more feasible approach in complex eyes. For instance, patients who benefit most are those with anterior chamber intraocular lenses (ACIOLs), large iridectomy/sectoral aniridia, iridocorneal adhesion, post-vitrectomy, aphakia, and sutured posterior chamber intraocular lenses (PCIOLs).
However, with increased experience, Descemet’s membrane endothelial keratoplasty (DMEK) is feasible in many of these eyes, Dr. Deng said.
Kevin Shah, MD, Eye Consultants of Pennsylvania, Wyomissing, Pennsylvania, uses ultra-thin DSAEK for certain patients, typically those who have been vitrectomized, have ACIOLs, glaucoma tube implants, and those who have had previous PKs.
“For any cases in which the anterior segment is disrupted and/or unicameral or there is hardware such as an anterior chamber intraocular lens, a DSAEK is indicated and DMEK would be contraindicated,” said Neda Shamie, MD, Advanced Vision Care, Los Angeles, California. “Also, if the view into the anterior chamber is limited, it would make a DMEK surgery far more complex and would pose a relative contraindication.”
By 2016, DSAEK was performed in more than 21,000 cases and DMEK in more than 6,000, said Massimo Busin, MD, professor of ophthalmology, Department of Morphology, Surgery, and Experimental Surgery, University of Ferrara, Ferrara, Italy.
“With few exceptions, DSAEK is still the more popular type of EK and for certain eyes the only available choice,” Dr. Busin said.
However, Dr. Shah noted that the number of DMEK cases continues to increase annually while the number of DSAEK cases is beginning to decrease.

Rebubble rate

The high rebubble rate in DMEK has improved as techniques and instrumentation have evolved, Dr. Busin said.
“My personal rebubble rate is now less than 10%, and although it’s higher than my DSAEK rebubble rates, the benefits in more rapid vision recovery, better visual outcome, and lower rejection rate justify the learning curve,” Dr. Busin said.
Dr. Deng noted that the rebubbling procedure is easier to perform than the repositioning in DSAEK.
“It takes 5 minutes at the office or minor procedure room,” Dr. Deng said. “The rebubble rate seems to be at the same rate observed in DSAEK after the learning curve.”
Rebubbling is a “minor accident” in the postop course of DMEK and occurs in 5% to more than 50% of cases, depending on many factors, Dr. Busin said. Patients should be advised about this possibility before undergoing DMEK, but they can also be told that uncomplicated rebubbling seldom affects the final outcomes.

Ultra-thin option

Dr. Shamie said the surgical technique is easier with ultra-thin DSAEK but that the vision quality and optimal vision may still be better with DMEK in certain patients.  
“I would suggest having all of these techniques in one’s armamentarium to be able to customize the treatment to the patient’s condition and visual needs,” Dr. Shamie said.
The current data suggest that ultra-thin DSAEK is better than DSAEK, Dr. Deng said, but there is not enough data to compare the procedures directly.
Both procedures deliver excellent BCVA, Dr. Shah said. For his ultra-thin DSAEK cases, Dr. Shah requests tissue of 40–70 microns.
“My DMEK patients have a higher chance of achieving 20/20 BCVA compared to ultra-thin DSAEK,” Dr. Shah said. “Also, because of thinner tissue in DMEK, I am seeing a slightly lower rejection rate with DMEK. But again, we need larger studies that evaluate the role of ultra-thin graft thickness with rejection and BCVA.”
The ideal candidates for DMEK over ultra-thin DSAEK are patients who have a premium IOL.
“DMEK works great with toric IOLs and results in a smaller hyperopic shift compared to ultra-thin DSAEK,” Dr. Shah said.

Patient communication

Patient discussions about the different forms of EK should include the surgeon’s experience with DSAEK and DMEK, Dr. Deng said.
“The surgeon should inform the patient that DMEK appears to have better visual outcomes but the air injection rate is higher in the early learning curve,” Dr. Deng said. “My experience is that as long as patients understand the risks and benefit of each procedure, they often are willing to go with DMEK.”
Dr. Busin tells patients that DSAEK has a somewhat slower recovery of vision, but less complications. One exception is for the risk of immunologic rejection, which is minimal in DMEK.
However, Dr. Shah has found that unless a patient directly asks about the nuances among DMEK, ultra-thin DSAEK, and DSAEK, going into the details about the procedures is often overwhelming and confusing for patients.
“Having said that, I typically let my patients know about the different types of EK, but focus on the surgery I think is most appropriate for them,” Dr. Shah said.
He provides them with handouts explaining the different forms of EK and has them come back for an additional visit, typically with a family member, prior to surgery to address any questions or concerns.
Although more data and long-term studies with ultra-thin DSAEK are needed, Dr. Shah said, a consensus is that the 3-year rejection rate is 1–2.5% for DMEK, 3–6% for ultra-thin DSAEK, and 5–10% for standard DSAEK.
There is general evidence that EK has less rejection than PK, Dr. Busin said. He noted that prolonged steroidal treatment can lower DMEK rejection rates below 1% annually at 2 years. However, the higher DSAEK rejection rate remains much lower than PK. In his statistics review, Dr. Busin found a 6.9% rejection rate at 5 years for ultra-thin DSAEK, compared to a 17% rate for DSAEK and 2.4% for DMEK.

Patient selection

Dr. Deng said selecting which procedure to use is based on surgeons’ experience.
“I do DMEK in every patient except the aphakic and those with ACIOLs,” Dr. Deng said.
All eyes with anatomical abnormalities that may cause graft luxation into the vitreous cavity are suitable only for DSAEK or ultra- thin DSAEK, Dr. Busin said.
“It is useless to choose DMEK in eyes with poor visual potential, as 20/20 vision does not come in question,” Dr. Busin said. “In general each surgeon should choose the method he is comfortable with, as long-term results show identical visual outcomes for DSAEK, ultra-thin DSAEK, and DMEK.”
Among patients with glaucoma or post-glaucoma surgery, Dr. Shamie said the selection of procedures depends on the condition of the anterior segment.
“If the iris structures are normal and there are no large iridotomies, if the tube is not too disruptive in the AC, and if the patient’s corneal view allows for DMEK surgery, I would proceed with DMEK,” Dr. Shamie said. 
However, the difficulty of air tamponade in post-surgical glaucomatous eyes may make DSAEK preferable, unless other issues are more relevant, Dr. Busin said. For instance, surgeons may limit possible immunologic rejection in eyes at higher risk by preforming DMEK.
Dr. Deng has found in her experience that DMEK is better for glaucoma patients.
“We have published our outcomes of DMEK in eyes with previous glaucoma surgery,” Dr. Deng said.1 “However, the majority of surgeons still feel more comfortable with DSAEK in these patients.”

Reference

1. Aravena C, et al. Outcomes of Descemet membrane endothelial keratoplasty in patients with previous glaucoma surgery. Cornea. 2017;36:284–289.

Editors’ note: Dr. Shamie has financial interests with SightLife (Seattle) and KeraLink (Baltimore). Dr. Busin has financial interests with Moria (Antony, France). Drs. Shah and Deng have no financial interests related to their comments.

Contact information

Busin
: massimo.busin@unife.it
Shah: kevin.j.shah@gmail.com
Shamie: nshamie@doheny.org
Deng: deng@jsei.ucla.edu

New trends in endothelial keratoplasty New trends in endothelial keratoplasty
Ophthalmology News - EyeWorld Magazine
283 110
220 143
,
2018-01-05T08:32:30Z
True, 1