Figure 15-24 Endothelial graft rejection in DSEK, characterized by scattered keratic precipitates without an endothelial

rejection line. (Courtesy of Robert W. Weisenthal, MD.)

Endothelial cell loss In DSEK surgery, the manipulation of tissue that accompanies microkeratome dissection; placement and orientation of the tissue within the anterior chamber; and primary injection of air to faciliate graft adherence or bubbling to treat dislocated grafts—all of these maneuvers potentially contribute to endothelial cell loss. However, at 5-year follow-up by Price and colleagues in a series of 95 eyes, mean cell loss was only 53%, comparing favorably to results of the Cornea Donor Study in patients undergoing PK, which showed a mean cell loss of 70% at 5 years. Long-term follow-up is necessary to confirm these results.

Additional complications associated with DSEK are similar to those seen in PK, including suprachoroidal hemorrhage, retinal detachment, cystoid macular edema, and graft rejection.

Li JY, Terry MA, Goshe J, Shamie N, Davis-Boozer D. Graft rejection after Descemet’s stripping automated endothelial keratoplasty: graft survival and endothelial cell loss. Ophthalmology. 2012;119(1):90–94. Epub 2011 Nov 23.

Price MO, Fairchild KM, Price DA, Price FW Jr. Descemet’s stripping endothelial keratoplasty: five-year graft survival and endothelial cell loss. Ophthalmology. 2011;118(4):725–729.

Ratanasit A, Gorovoy MS. Long-term results of Descemet stripping automated endothelial keratoplasty. Cornea. 2011;30(12):1414–1418.

Descemet Membrane Endothelial Keratoplasty

Another modification in EK, also suggested by Melles, is to transplant only donor Descemet membrane and endothelial cells but not stromal tissue. This procedure is referred to as Descemet

membrane endothelial keratoplasty (DMEK). The postoperative visual outcome of DMEK is touted as being superior to that of DSEK, and the incidence of graft rejection may be lower. However, the extended learning curve, the increased risk of loss of donor tissue during preparation, the increased difficulty of intraocular manipulation of the thin and friable tissue (increasing endothelial cell loss), and the increased incidence of graft detachment have made it a more challenging technique for the cornea surgeon but one that is increasingly utilized.

A curious phenomenon has prompted the development of a new technique that is a variation of DMEK and may increase its utilization. As clinical experience with DMEK has increased, there have been a number of cases in which corneal clearance occurred despite the presence of a subtotal graft detachment in DMEK. This finding suggested that endothelial migration across the posterior cornea could lead to restoration of corneal clarity. However, the mechanism underlying the endothelial migration was not clear.

To learn more about this process, investigators conducted a series of clinical studies in which descemetorrhexis was followed by implantation of a free-floating donor graft of Descemet membrane and endothelial cells in the recipient eye and no further manipulation was performed, a technique called Descemet membrane endothelial transfer (DMET). Twelve patients (7 with Fuchs dystrophy and 5 with pseudophakic bullous keratopathy [PBK]) were enrolled. After 6 months, all 7 patients with Fuchs dystrophy had corneas that had cleared and returned to normal thickness; however, corneal clearance did not occur in any of the patients with PBK. The studies’ authors postulate that in Fuchs dystrophy, the abnormal Descemet membrane produces a secondary endothelial dysfunction with viable endothelial cells. In this setting, descemetorrhexis with implantation of donor tissue may stimulate migration of host or donor endothelial cells, although whether the donor tissue interacts with the host endothelial cells or serves as the source of the endothelial cells is unknown. The authors speculate that in PBK, the corneal edema does not resolve because there is endothelial depletion rather than a dystrophic Descemet membrane. In patients with PBK, a standard DMEK procedure is necessary to achieve corneal clarity.

This raises the possibility that in patients with an abnormal Descemet membrane (Fuchs and posterior polymorphous dystrophy), replacement of the abnormal Descemet membrane with freefloating donor tissue may stimulate migration of endothelial cells either from the donor tissue or from the peripheral host endothelium. In another report, corneal clearance occurred without placement of any tissue after removal of Descemet membrane and endothelium, suggesting that it may not be necessary to use donor tissue at all to stimulate migration of the peripheral host endothelial cells.

Dapena I, Ham L, Netuková M, van der Wees J, Melles GR. Incidence of early allograft rejection after Descemet membrane endothelial keratoplasty. Cornea. 2011;30(12):1341–1345.

Dirisamer M, Dapena I, Ham L, et al. Patterns of corneal endothelialization and corneal clearance after Descemet membrane endothelial keratoplasty for Fuchs endothelial dystrophy. Am J Ophthalmol. 2011;152(4):543–555.e1.

Dirisamer M, Ham L, Dapena I, van Dijk K, Melles GR. Descemet membrane endothelial transfer: “free-floating” donor Descemet implantation as a potential alternative to “keratoplasty.” Cornea. 2012;31(2):194–197.

Dirisamer M, van Dijk K, Dapena I, et al. Prevention and management of graft detachment in Descemet membrane endothelial keratoplasty. Arch Ophthalmol. 2012;130(3):280–291. Epub 2011 Nov 14.

Dirisamer M, Yeh RY, van Dijk K, Ham L, Dapena I, Melles GR. Recipient endothelium may relate to corneal clearance in Descemet membrane endothelial transfer. Am J Ophthalmol. 2012;154(2):290–296.

Guerra FP, Anshu A, Price MO, Giebel AW, Price FW. Descemet’s membrane endothelial keratoplasty: prospective study of 1- year visual outcomes, graft survival, and endothelial cell loss. Ophthalmology. 2011;118(12):2368–2373.

Guerra FP, Anshu A, Price MO, Price FW. Endothelial keratoplasty: fellow eyes comparison of Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty. Cornea. 2011;30(12):1382–1386.

Shah RD, Randleman JB, Grossniklaus HE. Spontaneous corneal clearing after Descemet’s stripping without endothelial replacement. Ophthalmology. 2012;119(2):256–260. Epub 2011 Oct 7.