Marieke Bruinsma

Standardized ‘no-touch’ donor tissue preparation for DALK and DMEK: harvesting undamaged anterior and posterior transplants from the same donor cornea

Purpose:  To describe a standardized ‘no‐touch’ harvesting technique of anterior and Descemet membrane (DM) grafts for use in deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK), which provides undamaged anterior and posterior corneal grafts.

Descemet membrane endothelial transfer.

Purpose of review To elaborate on the recent concept of Descemet membrane endothelial transfer (DMET) and to explore the concepts that underpin its success through reviewing the key articles that have challenged our current understanding of corneal endothelial cell behavior. Recent findings DMET challenges the paradigm that complete graft–host apposition is required for successful corneal clearance in endothelial keratoplasty. It offers the promise of a simpler procedure to restore corneal clarity. Its success may lie in the ability of endothelial cells to migrate and proliferate. Endothelial host cells have been found in isolation and at disparate locations among donor cells within the corneal buttons of patients who have had a penetrating keratoplasty. New evidence for the continued slow proliferation of endothelial cells from the corneal periphery throughout life comes from the microanatomy of the peripheral cornea, and the demonstration of stem cell markers and markers of DNA synthesis in this area. Summary DMET offers us a tantalizing taste of a simpler way of treating corneal endothelial disease by harnessing the ability of corneal endothelial cells to migrate and proliferate. An understanding of these processes will be the key stepping stone to developing future treatments for corneal endothelial disease.

Association Between Graft Storage Time and Donor Age With Endothelial Cell Density and Graft Adherence After Descemet Membrane Endothelial Keratoplasty

IMPORTANCE After retrospectively evaluating the clinical outcome of 500 consecutive cases after Descemet membrane endothelial keratoplasty (DMEK), we extended the analysis in this study by assessing the effect of donor-related parameters on endothelial cell density (ECD) decline and detachment rate in this group. OBSERVATIONS This retrospective case series included 500 cases who had undergone DMEK from October 2007 to September 2012 at the Netherlands Institute for Innovative Ocular Surgery (NIIOS), Rotterdam, the Netherlands. Logistic regression analysis (n = 332 eyes) showed that donor age might be associated with a 3% increase in the risk for a detachment (odds ratio, 0.97; 95% CI, 0.94-1.00; P = .049) (ie, higher donor age seems to be associated with lower chances of a detachment). In addition, linear regression analysis indicated that graft storage time in medium was associated with ECD decrease (ie, the longer the storage time, the larger the decrease at 6 months after DMEK) (P = .01). CONCLUSIONS AND RELEVANCE We showed an association between graft storage time and ECD decline after DMEK and possibly between donor age and graft detachment. Therefore, donor storage times should be kept as short as possible to improve short-term ECDs. More research is needed to draw definite conclusions on the possible effect of donor age on the chance of a detachment after DMEK.

Histopathologic Features of Descemet Membrane Endothelial Keratoplasty Graft Remnants, Folds, and Detachments

PURPOSE To describe the histologic features of postmortem eyes after Descemet membrane endothelial keratoplasty (DMEK) and their potential clinical implications. DESIGN Histopathologic study. PARTICIPANTS Eleven postmortem DMEK corneas of 8 patients who underwent surgery for Fuchs endothelial dystrophy, with an average postoperative time of 4±1.9 years (range, 7 months-6.5 years). METHODS Eleven corneas transplanted with a DMEK graft were procured after death and processed for light microscopy evaluation. MAIN OUTCOME MEASURES Histologic findings at the donor-host interface and at the host edge. RESULTS Of the 11 corneas available for analysis, 9 showed normal anatomic features in the corneal center; that is, the donor-host interface resembled that of a virgin eye. One eye also had an anatomically normal periphery, but the remaining 10 eyes showed specific abnormalities in the periphery. Nine demonstrated overlapping of the DMEK graft onto the host edge of the descemetorhexis (and in 6 of these, the overlapping tissue showed a contracted inward fold at its peripheral edge with scar tissue); 1 eye showed a dense, acellular scar overlying a portion of the DMEK graft that clinically had shown a detachment followed by spontaneous adherence; 3 eyes showed subtle graft folds with scar tissue anteriorly; in 2 eyes (of the same patient), the anterior banded layer of the host Descemet membrane (DM) was still in situ across the cornea (both of these eyes had required rebubbling); and 2 eyes showed host DM remnants within the corneolimbal tunnel incision that may have interfered with incisional wound healing. CONCLUSION Incomplete host DM removal may relate to postoperative DMEK graft detachment and wound instability. Graft detachments may reattach with interface scarring. Rebubbling procedures may be performed within 4 to 6 weeks, before portions of the detached graft scar. Subtle DMEK graft folds may explain subjective reports of monocular diplopia.

Postmortem ultrastructural analysis of a cornea transplanted with Descemet membrane endothelial keratoplasty.

Purpose: The aim of this study was to describe the ultrastructure of the host–donor interface in the eye of a recently deceased patient, who had undergone Descemet membrane endothelial keratoplasty. Methods: The eye was enucleated postmortem, and after standard decontamination, the corneoscleral button was excised, cut into 4 quadrants, and processed for light and transmission electron microscopy evaluation. Results: Transmission electron microscopy revealed close attachment of the donors Descemet membrane to the hosts stroma and projection of stromal collagen fibers into the interfacial matrix, resembling a normal “virgin” corneal architecture. Conclusions: Ultrastructurally, an attached Descemet membrane endothelial keratoplasty graft closely resembles that of an unoperated, healthy eye with no appreciable adventitious or missing structures.

Novel 'heavy' dyes for retinal membrane staining during macular surgery: multicenter clinical assessment.

Purpose:  To evaluate the feasibility of two novel ‘heavy’ dye solutions for staining the internal limiting membrane (ILM) and epiretinal membranes (ERMs), without the need for a prior fluid‐air exchange, during macular surgery.

360-Degree Scheimpflug Imaging to Predict Allograft Rejection After Descemet Membrane Endothelial Keratoplasty.

Purpose: To describe the use of 360-degree Scheimpflug imaging as a diagnostic tool for detection and documentation of subtle corneal changes preceding upcoming allograft rejection after Descemet membrane endothelial keratoplasty (DMEK). Methods: A total of 17 eyes (16 patients) were diagnosed with clinically manifest allograft rejection 2 to 42 months after DMEK. 360-degree Scheimpflug images of consecutive follow-up examinations (from 3–60 mo) of “asymptomatic” eyes before, during, and after rejection were retrospectively analyzed, to determine which abnormalities could be detected before allograft rejection became clinically manifest. The images were compared with DMEK control eyes (without rejection episode). Results: Scheimpflug images at the time of rejection showed keratic precipitates as distinct retrocorneal nodular elevations and/or a significant increase in pachymetry of ≥7%. More subtle changes could be identified retrospectively in 9/17 eyes (53%) on an average at 8 (±5) months before rejection became clinically manifest; in all eyes, these subtle changes were not recognized at routine slit-lamp examinations by various ophthalmologists as inflammatory changes heralding allograft rejection. Secondary graft failure occurred in 4/17 eyes (24%). None of the control eyes showed relevant abnormalities with Scheimpflug imaging. Conclusions: By screening the posterior corneal surface with 360-degree Scheimpflug imaging, subtle inflammatory retrocorneal deposits can be detected and recorded during consecutive follow-up visits. Hence, Scheimpflug imaging may have the potential to become a diagnostic tool for early detection of upcoming allograft rejection in asymptomatic DMEK eyes, that is, before the immune response becomes clinically manifest and before substantial endothelial cell damage occurs.

Sex Chromosome Analysis of Postmortem Corneal Endothelium After Sex-Mismatch Descemet Membrane Endothelial Keratoplasty.

Purpose: To identify the origin of corneal endothelial cells (host or donor) present on grafts at various time points after Descemet membrane endothelial keratoplasty (DMEK), using fluorescence in situ hybridization (FISH) of sex chromosomes on post mortem corneas with sex mismatch between the donor and host. Methods: Corneoscleral buttons of 6 post mortem DMEK eyes of 4 patients, operated for Fuchs endothelial dystrophy, with an average postoperative time of 2.6 (±1.8) years (range, 7 months–4.5 years), of 2.5 (±1.7) years (range, 7 months–4 years), were processed for FISH detection of XX (female) or XY (male)-labeling signals in corneal endothelial cells in the central area of the DMEK graft. Two male patients underwent bilateral DMEK with grafts from female donors, and 2 female patients underwent unilateral DMEK and received a graft from a male donor. Results: FISH consistently showed the presence of donor endothelial cells across the graft area, with signaling of sex chromosomes opposite to the sex of the host. Conclusions: Donor endothelial cells may survive up to 4.5 years after DMEK. If so, the lower incidence of allograft rejection in DMEK may not be explained by early host cell replacement. Potential host cell migration may be limited by donor/recipient cell–cell contact inhibition.

Fuchs endothelial corneal dystrophy: current treatment recommendations and experimental surgical options

Fuchs endothelial corneal dystrophy is a common disorder characterized by the progressive thickening of Descemet membrane (DM), manifesting as guttae and leading to a decrease in endothelial cells and corneal clearance. Numerous studies have tried to better characterize the genetics of Fuchs endothelial corneal dystrophy, and suggest that it is a complex heterogenic disorder with an array of variants in severity and disease progression. Currently the most effective treatment for replacing diseased endothelium is endothelial keratoplasty (EK). In the last decade, EK has evolved into selective transplantation of an isolated DM and its endothelium, referred to as Descemet membrane endothelial keratoplasty (DMEK), which enables near normal anatomical and visual outcomes after surgery. Unexpected observations after DMEK, however, may bring new insights on endothelial cell wound healing, potentially allowing novel ‘non-keratoplasty’ surgical approaches like Descemet membrane endothelial transfer, endothelial cell injection techniques or even only a descemetorhexis as alternatives for selected cases.

Evaluation of the Suitability of Biocompatible Carriers as Artificial Transplants Using Cultured Porcine Corneal Endothelial Cells

ABSTRACT Purpose/Aim: Evaluating the suitability of bioengineered collagen sheets and human anterior lens capsules (HALCs) as carriers for cultivated porcine corneal endothelial cells (pCECs) and in vitro assessment of the cell-carrier sheets as tissue-engineered grafts for Descemet membrane endothelial keratoplasty (DMEK). Materials and Methods: pCECs were isolated, cultured up to P2 and seeded onto LinkCell™ bioengineered matrices of 20 µm (LK20) or 100 µm (LK100) thickness, and on HALC. During expansion, pCEC viability and morphology were assessed by light microscopy. ZO-1 and Na+/K+-ATPase expression was investigated by immunohistochemistry. Biomechanical properties of pCEC-carrier constructs were evaluated by simulating DMEK surgery in vitro using an artificial anterior chamber (AC) and a human donor cornea without Descemet membrane (DM). Results: During in vitro expansion, cultured pCECs retained their proliferative capacity, as shown by the positive staining for proliferative marker Ki67, and a high cell viability rate (96 ± 5%). pCECs seeded on all carriers formed a monolayer of hexagonal, tightly packed cells that expressed ZO-1 and Na+/K+-ATPase. During in vitro surgery, pCEC-LK20 and pCEC-LK100 constructs were handled like Descemet stripping endothelial keratoplasty (DSEK) grafts, i.e. folded like a “taco” for insertion because of challenges related to rolling and sticking of the grafts in the injector. pCEC-HALC constructs behaved similar to the DMEK reference model during implantation and unfolding in the artificial AC, showing good adhesion to the bare stroma. Conclusions: In vitro DMEK surgery showed HALC as the most suitable carrier for cultivated pCECs with good intraoperative graft handling. LK20 carrier showed good biocompatibility, but required a DSEK-adapted surgical protocol. Both carriers might be notional candidates for potential future clinical applications.