AFTER DSEK

Descemet’s-stripping endothelial keratoplasty (DSEK) has several advantages compared with penetrating keratoplasty (PK) in eyes requiring corneal transplantation. However, there are limited data on the long-term health of the partial thickness transplant. To address this gap, researchers from Mayo Clinic, Rochester, MN, analysed postoperative endothelial cell loss in prospectively followed cohorts from two consecutive trials evaluating PK (15 eyes) and DSEK (52 eyes) for endothelial disease. While the groups were derived from separate studies, their mean preoperative donor endothelial cell density (ECD) was similar, and all measurements were made using the same analysis technique of confocal microscopy images by the same masked observer. The results, which were reported at the 2013 annual meeting of the Association for Research in Vision and Ophthalmology (ARVO), showed a trend toward higher endothelial cell loss at one month postoperatively after DSEK compared with after PK (25 per cent vs. 19 per cent). Thereafter, endothelial cell loss after DSEK levelled off, and the percentage change from baseline ECD was significantly less after DSEK compared with after PK at two years (38 per cent vs. 47 per cent) and three years (44 per cent vs. 60 per cent). Nevertheless, initial data from five years after DSEK suggested its advantage at two and three years might only be temporary. Data from 10 eyes showed 60 per cent endothelial cell loss, approaching the cell loss at five years after PK as reported previously from Mayo and in the Cornea Donor Study. Sanjay V Patel MD, professor and chair, Department of Ophthalmology, Mayo Clinic, is the lead author of the study. He told EuroTimes, “Our DSEK data showing a trend toward higher endothelial cell loss immediately post surgery compared with PK followed by a more gradual decline are consistent with results reported in a retrospective study by Price et al. [Ophthalmology 2011;118(4):725-9].” He continued, “Our results from five years post-DSEK suggest that cell loss after DSEK might converge with that after PK over the longer-term. However, with the small number of eyes evaluated, more and longer-term data are needed to determine the long-term survival of DSEK grafts.” The investigators proposed that the benefit of less endothelial cell loss at two and three years after DSEK might be explained by the lowered threshold to operate on younger recipients with healthier peripheral endothelial cells, thus impairing cell migration from the donor. Alternatively, the explanation may relate to the use of a slightly larger graft in DSEK procedures compared with PK (mean 8.2 vs. 7.6mm) since the larger DSEK grafts contain a greater density of cells in the periphery that might buffer the overall cell loss rate versus PK. In addition, differences in host-graft anatomy may also play a role as the better alignment of the posterior surfaces of the donor and host after PK may enable easier and more rapid migration of healthy endothelial cells from graft to host. The researchers also reported that five DSEK grafts and none of the PK grafts failed during three years of follow-up. Four early DSEK graft failures occurred during the surgeons’ learning curve for the procedure. “Early graft failure remains much higher after DSEK than after PK, and elimination of these failed grafts from cell loss analyses will artificially contribute to improved cell loss after DSEK,” Dr Patel said.