Endothelial Keratoplasty
In 1998, Gerrit Melles introduced the concept of lamellar surgery for endothelial dysfunction through a procedure called deep lamellar endothelial keratoplasty (DLEK). Because the manual dissection (of the host and donor corneal tissue) in DLEK was technically challenging, this technique was not widely adopted by cornea surgeons. Melles modified the technique to include stripping of the host Descemet membrane and endothelium (descemetorrhexis) and insertion of a hand-dissected posterior lamellar donor button, which was positioned against the host with an air bubble in the anterior chamber; the revised technique was coined Descemet stripping endothelial keratoplasty (DSEK). Mark Gorovoy later automated the lamellar dissection of the donor tissue by using a microkeratome, giving rise to the procedure he called Descemet stripping automated endothelial keratoplasty (DSAEK). Over time, the term DSEK has been adopted for these automated procedures as well; in this book, the term DSEK is similarly used.
Melles further modified the DSEK procedure by using only donor Descemet membrane and endothelium in a procedure termed Descemet membrane endothelial keratoplasty (DMEK). Further innovations to the technique used to insert and unscroll the tissue, the adoption of an “S” stamp for graft orientation, and the use of SF6 gas to extend the duration of the gas bubble have significantly reduced the incidence of postoperative complications and increased the use and success of DMEK. In addition, the availability of eye bank–prepared tissue for DSEK and DMEK has increased the safety and popularity of both procedures.
EK is now the preferred technique for treatment of patients with corneal endothelial dysfunction, and it has been adopted for use in pediatric patients with congenital or early corneal edema (see the discussion of pediatric keratoplasty later in the chapter). Due to the success of, and rapid rehabilitation observed with, EK, the indications for this procedure have expanded to include patients with visually significant cornea guttae in the absence of stromal edema. Table 15-7 shows the increased use of DSEK and DMEK in the United States since 2014. Comparisons of PK and endothelial surgery are provided in Tables 15-6 and 15-8. Videos 15-7 through 15-10 show the DSEK and DMEK procedures.
Table 15-7 Statistics for DSEK and DMEK Procedures Performed in the United States, 2014–2017
Table 15-8 Comparison of Short-Term Results for Different Surgical Techniques for Corneal Edema (Fuchs Dystrophy and PBK)
VIDEO 15-7 Descemet stripping endothelial keratoplasty.
Courtesy of Robert W. Weisenthal, MD.
VIDEO 15-8 DSEK combined with phacoemulsification and IOL implantation.
Courtesy of Robert W. Weisenthal, MD.
VIDEO 15-9 Descemet membrane endothelial keratoplasty.
Courtesy of Robert W. Weisenthal, MD.
VIDEO 15-10 DMEK combined with phacoemulsification and IOL implantation.
Courtesy of Robert W. Weisenthal, MD.
Lee WB, Jacobs DS, Musch DC, Kaufman SC, Reinhart WJ, Shtein RM. Descemet’s stripping endothelial keratoplasty: safety and outcomes: a report by the American Academy of Ophthalmology. Ophthalmology. 2009;116 (9):1818–1830.
Section 6, Endothelial Keratoplasty. In: Mannis MJ, Holland EJ, eds. Cornea. Vol 2. 4th ed. Philadelphia: Elsevier; 2017:1427–1508.
Terry MA, Straiko MD, Veldman PB, et al. Standardized DMEK technique: reducing complications using prestripped tissue, novel glass injector, and sulfur hexafluoride (SF6) gas. Cornea. 2015;34(8):845–852.
Waggoner M, Cohen AW. Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). In: Basic Techniques of Ophthalmic Surgery. 2nd ed. San Francisco: American Academy of Ophthalmology; 2015:145–152.
Advantages
Because the donor tissue is inserted through a small corneal or scleral incision in EK procedures (compared with the large full-thickness central corneal incision used in other keratoplasty procedures), the structural integrity of the eye is preserved, and any subsequent trauma to the eye will result in less damage (Fig 15-15). Other advantages include reduced incidence of graft rejection, reduction in suture-related problems, less induced astigmatism with greater accuracy in IOL power calculations, and more rapid vision rehabilitation (due to preservation of the ocular surface and the rapid return of endothelial function).
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.