In Vivo Endothelial Cell Density Decline in the Early Postoperative Phase After Descemet Membrane Endothelial Keratoplasty

Purpose: To evaluate endothelial cell density (ECD) in the first 6 months after Descemet membrane endothelial keratoplasty (DMEK) by eliminating method error as a confounding variable. Methods: From 24 DMEK eyes operated for Fuchs endothelial corneal dystrophy, from which specular microscopy images could be taken at 1 day and 6 months postoperatively, ECD values were compared between these 2 time points. Results: Using the 1-day ECD measurement as baseline, mean ECD decreased from 1913 (+/- 326) cells/mm 2 to 1524 (+/- 393) cells/mm(2) at 6 months, a decline of -18 (+/- 19)%. With the 1-week ECD as baseline [1658 (+/- 395) cells/mm 2 ], the decline at 6 months was -6 ( +/- 19)% and when using preoperative ECD as baseline [2521 (+/- 122) cells/mm(2)], the decline was -39 (+/- 16)% at 6 months. Conclusions: After DMEK, ECD shows an in vivo decline of 18% from 1 day to 6 months postoperatively, with a sharp 13% drop in the first week, and a slower decrease thereafter. The remaining difference of 20% from preoperative ECD values may be attributed to a measurement error in the eye bank with an overestimation of the graft's viable endothelial cell population and/or intraoperative trauma to the graft.