Risk of graft rejection significantly lower with DMEK than DSEK or PK

This study retrospectively investigated whether the risk of allograft rejection is lower following Descemet's membrane endothelial keratoplasty (DMEK) compared with Descemet's stripping endothelial keratoplasty (DSEK) or penetrating keratoplasty (PK). The authors hypothesized that this may be the case since DMEK involves selective transplantation of only Descemet's membrane and endothelium, without any accompanying stroma. The results, reported in March in Ophthalmology, indicate that patients at one center who underwent DMEK had a significantly lower risk of experiencing a rejection episode within two years after surgery compared with those who underwent DSEK or PK at the same location.

The authors calculated rejection-free survival and cumulative probability of a rejection episode for 141 eyes treated with DMEK, 598 with DSEK and 30 with PK. The patients all had similar demographics, follow-up duration, indications for surgery, postoperative steroid regimen and rejection criteria. DMEK eyes were followed for a median of 13 months (range, 3 to 40 months).

One DMEK patient (0.7 percent) experienced a documented rejection episode compared with 54 (9 percent) treated with DSEK and 5 (17 percent) with PK. The Kaplan-Meier cumulative probability of a rejection episode at one and two years was 1 percent and 1 percent, respectively, for DMEK; 8 percent and 12 percent, respectively, for DSEK; and 14 percent and 18 percent, respectively, for PK (P = 0.004). The risk of experiencing a rejection episode was 15 times lower in DMEK than DSEK eyes and 20 times lower in DMEK than PK eyes.

The authors conclude that reduced rejection rates with DMEK could lead to improved long-term graft survival, better patient care and management, reduced use of topical corticosteroids, and a lower risk of steroid responsiveness and glaucomatous damage. Reduced rejection rates could have a significant impact on eye banking and donor tissue availability, especially in the developing world. The authors also say that reduced steroid dosing and, in turn, fewer postoperative IOP spikes also would decrease the need for topical antiglaucoma medications and reduce health care costs.