Presence of Diabetes, Complications in Donors Reduce Odds of Successful DSEK

The Cornea Preservation Time Study (CPTS) is the largest, prospective, randomized, double-masked clinical trial of modern corneal transplantation to date. It involved more than 1300 Descemet stripping endothelial keratoplasty (DSEK) procedures performed by 70 experienced surgeons. By allowing a variety of DSEK techniques and postoperative care regimens, CPTS functioned as a real-world study.

One of the previously reported primary outcomes from this study was that preservation time up to 11 days had little effect on graft success up to 3 years.^[1] A recently published analysis^[2] of donor, recipient, and operative factors from CPTS has now identified some other interesting outcomes from this important study.

After controlling for preservation time, researchers found that tissue from donors with diabetes was associated with twice the risk for primary or early graft failure, a finding not seen in any prior large study on DSEK. Regardless, it must be noted that successful outcomes were obtained from 90% of tissue from donors with diabetes.

The CPTS did not collect data on the specifics of the diabetes, such as duration of diabetes, insulin dependence, and severity of diabetes, including ocular and systemic complications. My sense is that not all diabetic donor tissue is equal. Tissue from a donor who has had insulin-dependent diabetes for 40 years may well act differently than tissue from a donor with recently diagnosed diet-controlled diabetes. Future studies need to offer and evaluate more specific data in this area. Measuring the donor's hemoglobin A1c level may also be useful in quantifying the severity of the diabetes. Ideally, a prospective trial could be designed to assess the effect of different forms, duration, and severity of diabetes on the success of DSEK. As the success rate for donors with diabetes is still very high, most surgeons are using diabetic tissue for DSEK.

Other secondary findings from this study are less surprising. Eyes with pseudophakic or aphakic corneal edema had a lower success rate at 3 years (84%) compared with eyes with Fuchs endothelial dystrophy (94%), mainly because of late graft failures. This is most likely a result of healthier endothelial cells in the corneal periphery (endothelial reserve) in eyes with Fuchs dystrophy than in eyes with pseudophakic or aphakic corneal edema, causing the need for greater migration of the donor cells to the periphery in the latter cohort.

Surgical complications were the only operative factor found to affect graft success. Eyes with complications during surgery had a 3-year success rate of 80% versus 95% in eyes without operative complications. The other operative factors of venting incisions and peripheral stromal scraping were not associated with graft success.

Donor factors, such as sex, age, preoperative endothelial cell density, and graft diameter, were not predictors of graft success. Although there was a trend for lower long-term success in eyes with prior glaucoma surgery, it did not reach statistical significance, perhaps because only 31 eyes in the CPTS had prior glaucoma surgery.

Recipient factors, including sex, age, and history of diabetes, were not found to be associated with graft success.

Last, although I believe that many, if not most, of these findings are also true for Descemet membrane endothelial keratoplasty, prospective studies are needed to definitively determine that.

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