COMMENTARY

Corneal Graft Success Over 30 Years: Comparing Surgical Techniques in a Specific French Region

Christopher J. Rapuano, MD

Disclosures

April 05, 2016

Viewpoint

In France, as in much of the world, PK was essentially the only corneal transplant procedure performed until the first decade of this century. Around that time, both anterior and posterior lamellar keratoplasties became more mainstream.

In the United States, whereas the percentage of anterior lamellar keratoplasties remains relatively low, the percentage of EKs continues to rise, with more EKs than PKs being performed several years ago. For this dramatic change in behavior to occur, surgeons must believe that EKs are superior to PKs for most patients.

Several case series[1,2,3,4,5] have demonstrated the superiority of EK over PK for eyes with endothelial disease. More recently, however, a couple of large "real-world" multicenter or registry studies[6,7] have looked at graft survival, comparing different surgical techniques, and have not found EK to be better than PK.

In this study, the authors prospectively recorded their graft survival data for all corneal transplants in an entire region of France over 30 years. They estimate that their center provides 96% of all corneal grafts in their catchment area, which limits selection bias. In addition, only two or three surgeons performed all the grafts during each period, limiting surgeon experience as a confounding variable.

Not surprisingly, the percentage of grafts for PBK declined over the three decades, probably owing to improvements in cataract surgery techniques. The percentage of grafts for Fuchs dystrophy increased, most likely because of an expanded indication for keratoplasty at an earlier stage of this disease. The percentage of grafts for keratoconus decreased from the second to third decades; this finding is perhaps related to better therapeutic options, such as specialty contact lenses, intracorneal rings, and corneal crosslinking.

I was somewhat surprised that the 5-year graft survival, even after adjustment for prognostic actors, did not significantly improve from the first to third decades of the study. Having performed grafts for 25 years, my sense is that graft survival has improved, but perhaps that is just wishful thinking.

I was most curious about the authors' EK results. Unfortunately, owing to the relatively small sample size (which made them combine Descemet stripping endothelial keratoplasty [DSEK] with Descemet membrane endothelial keratoplasty [DMEK]) and the short follow-up time, they only looked at 1-year graft survival for EK compared with PK. I was shocked to see the 1-year graft survival for EK was only 60%, whereas the graft survival for PK was 91%.

In an attempt to exclude the possible negative effects of the learning curve of DSEK and DMEK on graft survival, the authors then excluded DSEKs and DMEKs performed in the first year of their experience. That adjustment decreased the hazard ratio from 3.22 to 1.50—which, although no longer statistically significant, still indicates that 1-year graft survival may be worse for EK than PK. If anything, I would have expected the graft survival for EK to be better than the graft survival for PK, and because these were not randomized cases, I think the tendency would have been to perform EK in eyes with the best prognosis and PKs in the more "problematic" eyes.

The authors do acknowledge a crucial point, which is that graft survival is not the only determinant of graft success. Visual acuity, vision-related quality of life, and visual recovery after surgery are also important to both surgeons and patients. Most surgeons (and patients) believe that these postoperative outcomes are better after EK than PK. There is also good evidence that there is a lower rejection rate after EK than PK, which should improve graft survival rates with longer follow-up than the 1 year evaluated in this study.

Abstract

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