A recent study investigated six-month endothelial cell density (ECD) as a predictor for long-term ECD outcome and graft survival after DMEK in eyes with Fuch’s endothelial corneal dystrophy (FECD). The researchers found that greater, earlier cell loss post-DMEK negatively affects long-term outcomes.

The retrospective study included 585 DMEK eyes of 443 patients whose surgery indication was FECD. The researchers divided the eyes into four groups based on their six-month ECD quartiles:

• Group 1 (n=146): 313 to 1,245 cells/mm²
• Group 2 (n=148): 1,246 to 1,610 cells/mm²
• Group 3 (n=145): 1,611 to 1,938 cells/mm²
• Group 4 (n=146): 1,939 to 2,760 cells/mm²

The researchers further divided Group 1, the eyes with the lowest ECD at six months, into the following four subgroups

• Subgroup 1a (n=36): ≤828 cells/mm²
• Subgroup 1b (n=37): 829 to 1,023 cells/mm²
• Subgroup 1c (n=37): 1,024 to 1,140 cells/mm²
• Subgroup 1d (n=36): 1,141 to 1,245 cells/mm²

They found that mean preoperative donor ECD of the entire study group decreased from 2,543 cells/mm² to 1,584 cells/mm² at six months postoperatively, a rate of change of -38%. Group 1 had a graft survival probability of 95% at five years and also saw an ECD decrease in 99 eyes from an average of 951 cells/mm² at six months to 735 cells/mm² at five years. This probability was significantly lower than that of the other three groups. Similarly, Subgroup 1a had a significantly lower five-year graft survival probability (79%) compared with Subgroups 1b through 1d. The researchers noted that preoperative ECD didn’t influence graft survival.

“Our results on low six-month ECD being predictive for late endothelial failure are in line with previous studies on DSAEK and PK eyes,” the researchers wrote in their paper. “If six-month ECD is predictive for late endothelial graft failure after DMEK, it may be important to assess measures to prevent early endothelial cell loss and to enhance DMEK graft longevity.”

“In an earlier study, we [showed] that main risk factors associated with higher endothelial cell loss at six months postoperatively were minor graft detachment, cardiovascular donor death cause, recipients’ advanced stage of FECD and occurrence of postoperative complications such as allograft rejection and high IOP,” the researchers said. They noted that other studies have suggested graft storage medium, preoperative donor ECD and intraoperative complications can have effects on postoperative ECD, but the studies did not demonstrate consistent outcomes.

Their current study concluded that preoperative graft quality assessment should be optimized to ensure a high ECD at six months post-op. They also suggested that minimizing cellular stress from the graft and developing therapeutic options for eyes with unavoidable low post-op ECD could help improve graft longevity.