We would like to congratulate Stewart and associates on their keen observation on the “endothelialization” of the lateral edge of a Descemet stripping endothelial keratoplasty (DSEK) graft, that is, the presence of a newly formed Descemet membrane with endothelium covering the peripheral donor posterior stromal margin. As stated in their letter, this finding is indicative for endothelial migration after endothelial transplantation. Although the endothelium has been described to cover small defects, for example after penetrating keratoplasty, apparently it has capacity to cover far larger areas.

Although the donor was male and the recipient female, the pathology specimen did not allow identification of Barr-bodies (condensed X chromosome in female cells), to determine if the newly formed endothelial cells were of donor or recipient origin (Stewart, personal communication, 2009). Future studies on explanted DSEK or Descemet stripping automated endothelial keratoplasty (DSAEK) grafts may disclose what endothelial migration patterns occur following (endothelial) keratoplasty.