The aim of this study was to compare the efficacy and side effects of prednisolone acetate 1% versus fluorometholone 0.1% after Descemet membrane endothelial keratoplasty (DMEK). DMEK recipients used prednisolone acetate 1% for 1 month, and they were randomized to either prednisolone or fluorometholone for months 2 through 12. Dosing was 4 times daily in months 1 to 3, thrice daily in month 4, twice daily in month 5, and once daily in months 6 to 12. The main outcomes were immunologic rejection episodes and intraocular pressure (IOP) elevation (defined as ≥24 mm Hg or ≥10 mm Hg increase over the preoperative baseline level), assessed by the Kaplan-Meier survival analysis. The study included 325 eyes (99% were white, 96% had Fuchs dystrophy, and 9% had a previous glaucoma diagnosis). No eyes (0%) assigned to prednisolone versus 2 eyes (1.4%) assigned to fluorometholone experienced a possible (n = 1) or probable (n = 1) rejection episode (P = 0.17). Both rejection episodes resolved successfully with increased topical steroids. In the prednisolone arm, a significantly higher proportion exceeded the defined IOP elevation threshold (22% vs. 6%, P = 0.0005), and glaucoma medications were initiated or increased more often (17% vs. 5%, P = 0.0003). The most frequent reasons for discontinuing the assigned intervention were IOP management (n = 13 eyes assigned to prednisolone) or inflammation management (n = 3 eyes assigned to fluorometholone). One-year endothelial cell loss was comparable in both arms (30% vs. 31%, P = 0.50). DMEK has a remarkably low rejection episode rate (<1% through 1 year), as confirmed in this prospective randomized study. This provides a unique opportunity to reduce postoperative topical corticosteroid strength and thereby reduce the risk of steroid-associated complications.

For almost a century, penetrating keratoplasty has been the criterion standard for treating endothelial disorders, such as Fuchs endothelial dystrophy. Recently, it has been replaced by lamellar surgery, which has superior outcomes and a shortened time needed for complete visual rehabilitation.^1-4 Among the current strategies for lamellar replacement of the corneal endothelium, 2 approaches have gained special attention. Descemet stripping automated endothelial keratoplasty (DSAEK), currently in widespread use, involves lamellar splitting of the donor tissue with a microkeratome, resulting in grafts of about 100 to 200 µm thickness.⁵ More recently, Descemet membrane endothelial keratoplasty (DMEK) has been described as a sole transplantation of the Descemet membrane (DM) and corneal endothelium.⁶ Despite visual outcome of unsurpassed quality,^7-9 only a few corneal surgeons have adopted this technique. One of the major reasons is that postoperative detachment of the thinner grafts occurs more frequently in DMEK^7,8 than detachment of thicker stromal grafts in DSAEK.^10-13 Especially in the setting of outpatient surgery, repeated injections of air into the anterior chamber, so-called rebubbling, are associated with frequent follow-up visits and cause inconvenience to patients and surgeons.

To review recent advances in posterior lamellar keratoplasty and to describe strategies that enhance the outcome of Descemet's membrane endothelial keratoplasty (DMEK) and should lead to a more widespread use of this technique. DMEK offers significant advantages over Descemet's stripping automated endothelial keratoplasty (DSAEK) such as less immune reaction and better visual acuity because of less higher order aberrations. Donor selection should exclude donors under 50 years because of tissue elasticity; several advanced techniques now allow donor preparation from both cold and organ-cultured tissue in about 99% minimizing the risk of graft loss. Oversizing the area of Descemet's stripping in relationship to graft size enhances graft attachment and use of a standardized approach for graft delivery. Air bubble-driven nontouch unfolding techniques and, possibly, gas tamponade in the anterior chamber further enhance graft attachment and reduce surgery-induced endothelial cell loss. Graft orientation is made earlier by marking, slit beam and optical coherence tomography. Novel understanding of the functional anatomy of Descemet's membrane as well as migration of endothelial cells will allow to further refine DMEK and improve its outcome. Although the superiority of DMEK over Descemet's stripping automated endothelial keratoplasty in terms of safety and functionality had been further elucidated, remarkable progress has been made in the recent past regarding tissue preparation, insertion and intraoperative manipulation that will foster the more widespread use of DMEK among corneal surgeons.