DMEK or Ultrathin DSAEK
DMEK is gaining fans, but DSAEK remains preferable for certain indications
Massimo Busin MD
While corneal transplantation surgery in recent years has seen a shift towards Descemet’s Membrane Endothelial Keratoplasty (DMEK) for the reported benefits of quicker healing and better visual outcomes, procedures such as ultrathin Descemet’s Stripping Automated Endothelial Keratoplasty (UT-DSAEK) still have a valuable role to play for certain indications, according to Massimo Busin MD.
“DMEK is a viable option for some indications, but there are still many complex cases, with poor visibility and certain comorbidities for instance, that are better suited to UT-DSAEK. There is a substantial difference between the two procedures in terms of technical difficulty, and while probably there is faster visual rehabilitation with DMEK, in the long run it seems that the results are quite similar
especially if we use thin DSAEK grafts for our surgeries,” he told delegates attending the 9th EuCornea Congress in Vienna.
Prof Busin said that while DMEK has become more popular in the United States in recent years, the uptake has not been as dramatic as some had predicted. In 2011, the number of DSAEK procedures was 21,100 compared to 343 DMEK.
Five years later, the number of DMEK cases increased to 6,459 while DSAEK remained stable at 21,858. For 2017, 20,993 DSAEK procedures were performed compared to 7,622 DMEK cases.
“The percentage gains year on year for DMEK have been decreasing and there is a stable curve for DSAEK because it has been decreasing very slowly at about 2% a year. I think this tells us that we are almost reaching a balance between the two procedures where they both have a role to play depending on the particular eye that we need to treat,” he said.
Prof Busin said that DMEK is a good option, for instance in patients with Fuchs’ endothelial dystrophy, intact posterior capsule and normal anterior segment anatomy, and is also viable in failed DSAEK after penetrating keratoplasty cases.
“There are eyes that are good for DMEK, and certainly the number increases with surgical experience. However, there are other situations where DSAEK can be done and should be preferred to DMEK,” he said.
It is best to avoid DMEK in eyes with a shallow or poorly visualised anterior chamber, or those with communication between the anterior chamber and vitreous cavity, through which the donor endothelium may dislocate posteriorly and air tamponade may be challenging, said Prof Busin.
Similarly, UT-DSAEK may be better adapted to more complex cases with ocular comorbidities such as glaucoma or severe pseudophakic bullous keratopathy, and aphakic or vitrectomised eyes.
“Normal anatomy allows you to do DMEK or DSAEK or even PK in certain cases. In visually compromised eyes, however, such as after multiple retinal surgeries, it makes no sense to do DMEK hoping for a better visual result when the visual potential is so poor. Such patients end up happy with a visual improvement from hand motion to counting fingers by doing a DSAEK.
“So, we can perform DMEK under optimal conditions, but in other cases can still perform DSAEK whilst retaining the advantages of a lamellar graft compared to a PK,” he said.
COMPARABLE VISUAL OUTCOMES
While better visual rehabilitation is often cited as a motivating factor for some surgeons to convert to DMEK, Prof Busin said that the picture is actually more complex in reality. He noted that some of the results in the scientific literature compare DMEK to standard DSAEK rather than UT-DSAEK, which provides better visual outcomes thanks to thinner, more uniformly cut grafts. He also said that his own long-term data shows comparable visual outcomes for UT-DSAEK compared to DMEK.
“At six months the percentage of patients attaining 20/20 with UT-DSAEK is lower than DMEK, but five years after surgery we have similar rates of patients obtaining 20/20 and 20/25,” he said.
Although rejection rates are slightly higher with UT-DSAEK compared to DMEK, Prof Busin said that this is balanced out somewhat by the higher complication rate associated with DMEK, in particular for surgeons who are new to the procedure.
Massimo Busin: firstname.lastname@example.org