Novel Methods for Treatment of Endothelial Dysfunction
A number of case reports have described extensive, visually significant graft detachments; nonadherent, “free-floating,” grafts; and even an upside-down graft after DMEK in which the cornea cleared without additional intervention. The restoration of corneal clarity in these cases was thought to result from endothelial migration either from the peripheral cornea or from the free-floating donor tissue. After this experience, Dirisamer et al performed descemetorrhexis with implantation of a free-floating donor graft of Descemet membrane and endothelial cells, a technique called Descemet membrane endothelial transfer (DMET). In their study of 12 patients (7 patients with Fuchs endothelial corneal dystrophy [FECD] and 5 with pseudophakic bullous keratopathy [PBK]), all of the patients with FECD had clear corneas of normal thickness after 6 months; however, the patients with PBK did not improve and required further surgery. The authors suggested that descemetorrhexis in the patients with FECD, removing the thickened Descemet membrane characteristic of FECD, allowed the migration of endothelial cells from either the host or donor endothelial cells. In contrast, the corneal edema did not resolve in PBK because there was endothelial depletion in the host cornea.
Subsequently, other investigators attempted a standard descemetorrhexis of 8.0–8.5 mm without placement of donor tissue in patients with FECD. The results of this technique have been mixed, with some surgeons abandoning the procedure and some investigators continuing to look for ways to modify it for a more consistent and successful outcome. In one study of 13 eyes, the investigators opted to decrease the size of the central descemetorrhexis to 4 mm. Corneal edema was present in all 13 eyes in the immediate postoperative period. Four eyes were classified as fast responders, with resolution of the corneal edema occurring at 1 month, and 4 eyes were considered typical responders, with corneal clearing at 3 months. Two eyes were slow responders, with partial corneal clearing, and 3 eyes required EK. A pharmacologic approach such as the use of Rho-associated kinase inhibitors to induce host endothelial proliferation or endothelial cell culture using reprogrammed adult stem cells from the patient may improve the success of this descemetorrhexis without the use of donor tissue.
In an effort to expand the pool of donor tissue, a new technique has been introduced in which a single donor corneal button is divided into 2 segments for transplantation in 2 different patients. This technique, referred to as hemi-DMEK, may not be adopted in the United States because of regulatory, billing, and liability challenges, but it may be more acceptable in areas where there are donor shortages.
Arbelaez JG, Price MO, Price FW Jr. Long-term follow-up and complications of stripping Descemet membrane without placement of graft in eyes with Fuchs endothelial dystrophy. Cornea. 2014;33(12):1295–1299.
Borkar DS, Veldman P, Colby KA. Treatment of Fuchs endothelial dystrophy by Descemet stripping without endothelial keratoplasty. Cornea. 2016;35(10):1267–1273.
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, 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.
Koenig SB. Planned descemetorhexis without endothelial keratoplasty in eyes with Fuchs corneal endothelial dystrophy. Cornea. 2015;34(9):1149–1151.
Lam FC, Baydoun L, Satué M, Dirisamer M, Ham L, Melles GR. One-year outcome of hemi-Descemet membrane endothelial keratoplasty. Graefes Arch Clin Exp Ophthalmol. 2015; 253(11):1955–1958.
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.