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Publication Exclusive: PDEK emerging as promising but challenging alternative to DSEK, DMEK

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Endothelial keratoplasty has gained prominence over penetrating keratoplasty as the preferred corneal transplantation technique for numerous indications. Proponents say the newer technique improves vision with lower complication rates and faster visual recovery than full-thickness transplantation.

Currently, surgeons primarily perform two endothelial keratoplasty techniques: Descemet’s stripping endothelial keratoplasty and Descemet’s membrane endothelial keratoplasty.

DSEK involves removal of the Descemet’s membrane and endothelium from the recipient’s stroma and replacement with donor posterior stroma, Descemet’s membrane and endothelium.

DMEK also involves removal of the Descemet’s membrane and endothelium but with replacement of only these two layers, without posterior stroma. Between these two forms of endothelial keratoplasty, many surgeons believe that DMEK offers better visual and refractive outcomes, faster visual recovery and a lower graft rejection rate than DSEK.

An emerging technique, pre-Descemet’s endothelial keratoplasty, involves transplantation of the pre-Descemet’s, or Dua’s, layer, Descemet’s membrane and endothelium.

According to proponents of the technique, PDEK offers the ability to use corneal tissue from donors younger than 40 years. In addition, PDEK grafts are thicker than those used in DMEK and thinner than those used in DSEK, providing flexibility and ease of manipulation.

“PDEK is going to be, in my opinion, a big boon for corneal surgery because of these several advantages,” Amar Agarwal, MS, FRCS, FRCOphth, OSN APAO Edition Board Member, said. Agarwal, Harminder Dua and colleagues first performed PDEK in September 2013.

“The most significant advantage of PDEK is that it is not dependent on the corneal donor age, whereas DMEK cannot be done unless the donor is above 40 years of age, given the increased tendency for graft scrolling,” Agarwal said. “Additionally, a PDEK graft is advantageous in that it is only 25 µm to 30 µm thick, minimizing graft-host interface postoperative haze. Notably, even though the PDEK graft is thin, the pre-Descemet’s layer preservation within the graft is the critical component that allows for ease of graft movement within the eye, minimizing the risk of graft tearing.”

For the time being, DSEK and DMEK will remain the leading corneal transplantation techniques, according to Mark A. Terry, MD.

“DSEK surgery is the standby procedure that can be done for all forms of disease that require endothelial keratoplasty. That’s really the go-to procedure for most surgeons,” Terry said. “The DMEK procedure offers pure anatomic replacement, and because of that, it offers better quality of vision and faster rehabilitation than you can get with DSEK. So, I think that in the future that DMEK is going to be the dominant procedure for routine cases of endothelial replacement. But DSEK will always have a place in corneal transplant surgery for those complex cases of endothelial problems.”

Click here to read the full cover story published in Ocular Surgery News U.S. Edition, December 25, 2015.