Descemet Membrane Endothelial Keratoplasty Graft Research Articles

3D Mapping of the DMEK Detachment Area from OCT Scans of the Anterior Segment of the Eye - Clinical Applications.

Graft detachment is the most common complication after Descemet membrane endothelial keratoplasty (DMEK). To assess the amount of graft detachment, precision is limited when using slit-lamp biomicroscopy. Detachment of DMEK grafts can be assessed automatically on anterior segment optical coherence tomography (AS OCT) images and allows visualization of the area and volume of detachment using 3D maps. This article provides an overview of its applications such as accurately assessing the course of natural graft attachment, identification of potential risk factors for detachment and evaluation of the long-term effect of graft detachment. The 3D map of DMEK detachment may support researchers and clinicians in precise quantification of the area and volume of graft detachment even in large data sets, and the intuitive, fast and reliable evaluation.

Plastic vs. glass: the effect of the synthetic material in contact with DMEK tissue during staining on endothelial cell loss.

Endothelial cell loss (ECL) during Descemet membrane endothelial keratoplasty (DMEK) graft preparation has been shown to affect graft survival and the need for re-grafting. The purpose of this study was to quantitatively assess the impact of the plastic and glass mediums in contact with DMEK donor tissue during intra-operative graft staining on ECL. Retrospective study that included patients who underwent DMEK surgery between January 2019 and June 2021 at Hôpital Maisonneuve-Rosemont and the Jewish General Hospital in Montreal, Canada. DMEK grafts were stained with 0.06% Trypan blue ophthalmic solution (VisionBlue®, Dutch Ophthalmic, USA, Exeter, NH) for 120s in either a plastic or glass medium prior to delivery into the recipient's eye. The ECL was compared between the two groups 12-30months post-operatively. ECL at 12-30months was significantly less in the eyes that had received grafts stained in a plastic medium compared to those stained in a glass medium. Graft survival and re-bubbling was higher in the glass group however this difference was not statistically significant. Staining of the DMEK graft in a plastic medium caused less ECL compared to the glass medium.

Influence of Donor Factors on Descemet Membrane Endothelial Keratoplasty (DMEK) Graft Preparation Outcome.

To determine which donor characteristics, like previous diseases and surgeries, influence the severity of the DM/endothelial lamella preparation prior to DMEK-surgery. Retrospective cross-sectional single-center study is presented. Eight hundred and forty-six eyes with DMEK-surgery between 01/2018 and 01/2021 performed at the University Hospital Cologne, Germany, were included. Information regarding the donors' previous diseases and surgeries were provided by a large database of a cornea bank (Multi Tissue Bank Mecklenburg-Vorpommern) and merged with the Cologne DMEK database, which contains information regarding preparation characteristics of the surgeon-prepared graft directly preoperatively. Three preparation groups (easy, difficult and very difficult) were correlated to the donors' previous diseases and surgeries. The following characteristics were used for the assignment in one of the three groups: stripping difficulty, rolling and staining behavior, central and peripheral adherences, tissue fragility and DM-splitting. Significant risk factors for DM-splitting were diabetes mellitus (DMel) type II, heart failure, chronic kidney disease and previous cataract surgery (p=0.022, p=0.012; p=0.047 and p<0.001 respectively). Previous DMel (especially type 2) was significantly associated with the occurrence of central adherences (p=0.009). Several cardiovascular diseases (p-values between <0.001 and p=0.038), DMel type II, chronic kidney disease and previous cataract-surgery were associated with peripheral adherences (p=0.004; p=0.020 and p<0.001 respectively). Furthermore, pseudophakic donor eyes presented a higher degree of fragility of the graft (p<0.001). Age was a significant risk factor for difficult preparation (p<0.001). The staining of the graft was poorer in donors with chronic kidney disease (p=0.037). Donor diabetes mellitus type 2, heart failure, previous cataract surgery, chronic kidney disease and age are associated with a difficult DMEK graft preparation. For every one-year increment in donor age, the odds of having very difficult preparation were increased by 3%. Also, chronic kidney disease predisposes to a poor tissue staining with trypan blue during preparation.

Qualitative Blade Topology in Donor Cornea Punches and Corresponding Endothelial Cell Loss in PK and DMEK Grafts

Purpose: Two commonly used donor cornea punches were assessed using quantification of peripheral endothelial cell loss (ECL) and scanning electron microscopy (SEM) of blade topology and associated features on donor grafts. Methods: Penetrating keratoplasty (PK) (n = 8 pairs) and Descemet membrane endothelial keratoplasty (DMEK) (n = 8 pairs) grafts were prepared from mate donor corneas using Moria Busin or Corza Barron donor cornea punches (all punches were 7.5 mm) and analyzed for global and peripheral ECL. Punches were examined by SEM and subsequently used to prepare PK grafts from mate donor corneas (n = 3 pairs) that were also assessed by SEM. Results: For PK grafts, peripheral ECL caused by Busin and Barron punches was 4.2% ± 0.6% and 4.0% ± 0.9% (P = 0.62), respectively. For DMEK grafts, peripheral ECL caused by Busin and Barron punches was 3.6% ± 1.9% and 3.0% ± 1.3% (P = 0.48), respectively. SEM analysis of the Busin punch identified a rolled blade with a seam; the Barron punch is created from full rod stock and is seamless. Busin punch PK grafts have a ridge of stromal tissue that was not observed in the Barron PK grafts. Both punches exhibit anomalies along the blade edge, and the stroma of both grafts exhibited “drag lines.” Conclusions: Both punches caused similar and minimal ECL. In PK grafts, the seam of the Busin punch may be the source of the observed uneven stromal surface. Striations and debris on the cutting surfaces of both punches may produce drag lines in cut stroma. These topological features may contribute to uneven donor–recipient tissue apposition, leading to astigmatism after PK.

Corneal Endothelium Viability Assay Using Trypan Blue Dye After Preloaded Descemet Membrane Endothelial Keratoplasty Graft Preparation.

The purpose of this study was to establish a validated method, consistent with Eye Bank Association of America medical standards, for evaluating endothelial cell loss (ECL) from an entire Descemet membrane endothelial keratoplasty (DMEK) graft using trypan blue dye as an alternative to specular microscopy. Twenty-nine corneas were prepared for preloaded DMEK by a single technician, and the endothelium was stained with trypan blue dye for 30 seconds. The technician estimated total cell loss as a percentage of the graft and captured an image. Images were evaluated by a blinded technician using ImageJ software to determine ECL and compared with endothelial cell density from specular microscopy. Tissue processing intervals were analyzed for 4 months before and after implementation of this method. For the 29 grafts, there was no statistically significant difference ( t test, P = 0.285) between ECL estimated by a processor (mean = 5.8%) and ECL calculated using an ImageJ software (mean = 5.1%). The processor tended to estimate greater ECL than the actual ECL determined by ImageJ (paired t test, P = 0.022). Comparatively, postprocessing endothelial cell density measured by specular microscopy were higher compared with the preprocessing endothelial cell density (mean = 4.5% P = 0.0006). After implementation of this evaluation method, DMEK graft processing time intervals were reduced by 47.9% compared with specular microscopy evaluation ( P < 0.001). Our results show that visual ECL estimation using trypan blue staining by a DMEK graft processor is a reliable and efficient method for endothelial assessment. Unlike specular microscopy, this method achieves comprehensive visualization of the entire endothelium, reduces total time out of cold storage, and decreases total time required to prepare and evaluate DMEK grafts.

Predicting Long-Term Endothelial Cell Loss after Preloaded Descemet Membrane Endothelial Keratoplasty in Fuchs’ Endothelial Corneal Dystrophy: A Mathematical Model

(1) Background: This study offers a biexponential model to estimate corneal endothelial cell decay (ECD) following preloaded “endothelium-in” Descemet membrane endothelial keratoplasty (DMEK) in Fuchs’ endothelial corneal dystrophy (FECD) patients; (2) Methods: A total of 65 eyes undergoing DMEK alone or combined with cataract surgery were evaluated. The follow-up period was divided into an early phase (first 6 months) and a late phase (up to 36 months). Endothelial cell count (ECC) and endothelial cell loss (ECL) were analyzed; (3) Results: The half time of the ECD was 3.03 months for the early phase and 131.50 months for the late phase. The predicted time-lapse interval to reach 500 cells/mm2 was 218 months (18.17 years), while the time-lapse interval to reach 250 cells/mm2 was 349 months (29.08 years). There was no statistically significant difference between the ECL in DMEK combined with cataract extraction and DMEK alone at 24 months (p ≥ 0.20). At the late phase, long-term ECL prediction revealed a lower ECC half time in patients undergoing DMEK combined with cataract surgery (98.05 months) than DMEK alone (250.32 months); (4) Conclusions: Based on the mathematical modeling, a predicted average half-life of a DMEK graft could reach 18 years in FECD. Moreover, combining cataract extraction with DMEK could result in excessive ECL in the long term.

Evaluating the forces involved in bubble management in DMEK surgery: mathematical and computational model with clinical implications.

To model postoperative forces involved in Descemet membrane endothelial keratoplasty (DMEK) tissue adherence and bubble management, including the impact of surface tension on graft support, with a view towards clinical applications. Tennent Institute of Ophthalmology, Glasgow, and James Watt School of Engineering, University of Glasgow, Glasgow, United Kingdom. Mathematical modelling and computer simulation. Theoretical modelling of biphasic flow and interaction of gas, liquid and tissue within the anterior chamber for static horizontal scenario A (adherent DMEK with mobile bubble) and dynamic vertical scenario B (release of bubble due to pupil block following DMEK). The model assumed incompressibility for both fluids within realistically achievable pressure ranges. Cahn-Hilliard Navier-Stokes equations were discretised through the application of the Finite Element Method. Mathematical modelling and computer simulation showed bubble size, corneal curvature and force intensity influences surface tension support for DMEK tissue in scenario A. Scenario B demonstrated complex, uneven distribution of surface pressure on the DMEK graft during uncontrolled bubble release. Uneven pressure concentration can cause local tissue warping, with air/fluid displacement via capillary waves generated on the fluid-air interface adversely impacting DMEK support. We have quantitatively and qualitatively modelled the forces involved in DMEK adherence in normal circumstances. We have shown releasing air/gas can abruptly reduce DMEK tissue support via generation of large pressure gradients at the liquid/bubble/graft interfaces, creating negative local forces. Surgeons should consider these principles to reduce DMEK graft dislocation rates via optimised bubble size to graft size, longer acting bubble support and avoiding rapid decompression where possible.

Performance outcomes from a DMEK peeling and preparation wet lab

ObjectiveTo evaluate the Descemet membrane endothelial keratoplasty (DMEK) preparation performance of trainee surgeons in an ex vivo human donor cornea DMEK wet lab simulation setting.MethodsHuman donor corneoscleral rims unsuitable for...

Depth-dependent mechanical properties of the human cornea by uniaxial extension

The purpose of this study was to investigate the depth-dependent biomechanical properties of the human corneal stroma under uniaxial tensile loading. Human stroma samples were obtained after the removal of Descemet's membrane in the course of Descemet's membrane endothelial keratoplasty (DMEK) transplantation. Uniaxial tensile tests were performed at three different depths: anterior, central, and posterior on 2 × 6 × 0.15 mm strips taken from the central DMEK graft. The measured force-displacement data were used to calculate stress-strain curves and to derive the tangent modulus. The study showed that mechanical strength decreased significantly with depth. The anterior cornea appeared to be the stiffest, with a stiffness approximately 18% higher than that of the central cornea and approximately 38% higher than that of the posterior layer. Larger variations in mechanical response were observed in the posterior group, probably due to the higher degree of alignment of the collagen fibers in the posterior sections of the cornea. This study contributes to a better understanding of the biomechanical tensile properties of the cornea, which has important implications for the development of new treatment strategies for corneal diseases. Accurate quantification of tensile strength as a function of depth is critical information that is lacking in human corneal biomechanics to develop numerical models and new treatment methods.

Efficient reduction of the scrolling of Descemet membrane endothelial keratoplasty grafts by engineering the medium.

The Descemet Membrane Endothelial Keratoplasty (DMEK) procedure for corneal transplantation is challenging due to the need to unscroll the donor graft within the recipient's eye. This process of unscrolling is complex, time-consuming, leads to a loss of endothelial cells and, most importantly, can negatively impact the graft's adhesion and integration with the host tissue after surgery. This problem is particularly evident when the graft is young. However, the physics behind this scrolling is not well understood, and therefore no sustainable solution is attained. Here, we propose that the concentration gradient of the medium used during transplant leads to a displacement gradient across the graft thickness, resulting in an out-of-plane folding or scrolling of the graft tissue. Using chitosan bilayer-based experimental models, it is experimentally demonstrated that this diffusion-coupled-deformation phenomenon can successfully explain why younger donor grafts tend to scroll tighter than older ones. Most importantly, we illustrate here through experiments that the medium can be engineered to reduce the scroll tightness and thus reduce the surgical inconveniences and improve post-transplant recovery. STATEMENT OF SIGNIFICANCE: This paper addresses a major issue that surgeons face while doing Descemet Membrane Endothelial Keratoplasty (DMEK) in unscrolling grafts during the graft insertion procedure. The currently used tapping method to unscroll the graft inside the patient's eye significantly reduces endothelial cell count, thus affecting its lifetime. Surprisingly, the physics behind graft scrolling is not well understood, so no sustainable solutions are proposed by the medical community. In this work, we present the underlying mechanism of DMEK graft scroll and illustrate experimentally the reason for scroll tightness through a chitosan bilayer based experiment model. Most importantly, we have successfully demonstrated that the preserving medium of the grafts can be engineered to reduce scroll tightness.

Challenges of DMEK Technique with Young Corneal Donors' Grafts: Surgical Keys for Success-A Pilot Study.

To report on the surgical maneuvers recommended for a successful unfolding of very young donors in order to accomplish an uneventful Descemet Membrane Endothelial Keratoplasty (DMEK) surgery. Five patients (three females and two males, mean age 71.2 ± 6.7 years) with Fuchs endothelial cell dystrophy who underwent DMEK with very young donors (between 20 and 30 years old) were included. The following demographic data were assessed: donor's age, donor's endothelial cell density (ECD), preservation time, recipient's age and sex and unfolding surgical time. Best-corrected visual acuity (BCVA; decimal system), ECD and corneal central thickness (CCT) were assessed preoperatively and at 6-month follow-up. Donors' mean age was 23.6 ± 3.6 years (range 21 to 30) and the mean ECD was 2748.6 ± 162.6 cells/mm2. All of them underwent an uneventful DMEK as a single procedure performed by one experienced surgeon (MAG) with a mean unfolding time of 7.2 ± 4.9 min (range 4 to 15). The essential steps, including patient preparation as well as DMEK graft implantation, orientation, unrolling and centering are detailed. At 6 months, BCVA was 0.6 ± 0.2, ECD was 1945.0 ± 455.5 cells/mm2 and CCT was 497.0 ± 19.7 microns. We hereby present the keys to overcome tightly scrolled grafts of very young donors, which prove perfectly suitable for DMEK surgery. The graft shape tends towards a double-roll and specific maneuvers are strongly recommended.

Innate Immune Cytokine Levels in Eyes With Late Endothelial Keratoplasty Failure.

The aim of this study was to compare aqueous humor cytokine levels in eyes with an initial endothelial keratoplasty (EK) that cleared and later decompensated versus control eyes. In this prospective case-control study, aqueous humor samples were collected under sterile conditions at the start of planned cataract or EK surgery in normal controls (n = 10), Fuchs dystrophy controls with no previous surgery (n = 10) or previous cataract surgery only (n = 10), eyes with Descemet membrane EK (DMEK) endothelial decompensation (n = 5), and eyes with Descemet stripping EK (DSEK) endothelial decompensation (n = 9). Cytokine levels were quantified with the LUNARIS Human 11-Plex Cytokine Kit and compared using the Kruskal-Wallis nonparametric test and post hoc Wilcoxon pairwise 2-sided multiple comparison test. Levels of granulocyte-macrophage colony-stimulating factor, interferon gamma, interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-10, IL-12p70, and tumor necrosis factorα did not differ significantly between groups. However, IL-6 was significantly increased in DSEK regraft eyes versus controls without previous ocular surgery. IL-8 was significantly increased in eyes with previous cataract or EK surgery versus eyes without previous surgery, and IL-8 was significantly increased in DSEK regraft eyes versus eyes with previous cataract surgery. The levels of innate immune cytokines IL-6 and IL-8 were elevated in the aqueous humor of eyes with failed DSEK, but not with failed DMEK. The differences between DSEK and DMEK may be related to the lower inherent immunogenicity of DMEK grafts and/or the more advanced stage of some of the DSEK graft failures at the time of diagnosis and treatment.

Cost Drivers of Endothelial Keratoplasty: A Time-Driven Activity-Based Costing Analysis

To determine cost drivers of endothelial keratoplasty (EK) through evaluation of surgical costs and procedure length based on type of EK, use of preloaded grafts, and performance of simultaneous cataract surgery. This study was an economic analysis of EKs at a single academic institution using time-driven activity-based costing methodology (TDABC). EK surgical cases, including Descemet Membrane Endothelial Keratoplasty (DMEK) and Descemet Stripping Automated Endothelial Keratoplasty (DSAEK), at the University of Michigan Kellogg Eye Center from 2016 to 2018 were included in the analysis. Data and inputs were obtained via the electronic health record and from prior literature. Simultaneous cataract surgeries were included and separately categorized for analysis. EK expenses were determined with TDABC, a method for cost calculation that incorporates the time that key resources are used and each resource's associated cost rate. Main outcome measures included surgery length (in minutes) and day-of-surgery costs. There were 559 EKs included, 355 DMEK and 204 DSAEK. Fewer DSAEKs had simultaneous cataract extraction (47, 23%) than DMEK (169, 48%). Of the DMEKs, 196 (55%) utilized preloaded corneal grafts. DMEK cost $392.31 less [95% confidence interval ($251.05, $533.57), P < 0.0001] than DSAEK and required 16.94 fewer minutes [(14.16, 19.73), P < 0.0001]. DMEK cases that utilized preloaded corneal grafts cost $460.19 less [($316.23, $604.14), P < 0.0001] and were 14.16 minutes shorter [(11.39, 16.93), P < 0.0001]. In multivariate regression, preloaded graft use saved $457.19, DMEK (compared to DSAEK) saved $349.97, and simultaneous cataract surgery added $855.17 in day-of-surgery costs. TDABC cost analysis identified a day-of-surgery cost and surgical time reduction associated with the use of preloaded grafts for DMEK, DMEK compared to DSAEK, and isolated EK compared to EK combined with cataract surgery. This study provides an improved understanding of surgical cost drivers and margin incentivization, which may explain trends and indirectly influence patient care decisions in cornea surgery practices.

Comparison of Long-Term Outcomes of DSEK and DMEK in Fuchs Endothelial Dystrophy.

This study aimed to compare the long-term endothelial cell loss, graft survival, and clinical outcomes in patients with Fuchs endothelial dystrophy (FED) after Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK) using a standardized surgical protocol. Three hundred and six consecutive DSEK and DMEK grafts of 223 patients with FED performed by 8 surgeons between January 2006 and August 2022 were analyzed. The primary outcome measures were graft survival, endothelial cell loss, and best spectacle-corrected visual acuity. At 5 years, graft survival was 96% for both DSEK and DMEK eyes. The mean percentage of endothelial cell loss was 57.7 ± 17.1 in DSEK and 56.8 ± 15.2 in DMEK eyes ( P = 0.430). The mean best spectacle-corrected visual acuity was 0.13 ± 0.14 logMAR in DSEK and 0.01 ± 0.18 logMAR in DMEK grafts ( P <0.00001) at 5 years postoperatively. Rebubbling was performed in 7.8% DSEK and 2.1% DMEK grafts ( P = 0.441). Cox regression identified rejection episodes (HR 6.5; 95% CI: 1.70-24.8; P = 0.0062) as a significant contributing factor for graft failure. DMEK had superior visual acuity outcomes compared with DSEK in these patients up to 5 years after surgery. At 5 years, there was no significant difference in graft survival or endothelial cell loss between DSEK and DMEK eyes with FED. We propose that our standardized technique reduces the need for rebubbling.

Corneal Guttae After Descemet Membrane Endothelial Keratoplasty.

The aim of this study was to report on the occurrence of corneal guttae after Descemet membrane endothelial keratoplasty (DMEK). In this retrospective case series, 13 eyes of 13 patients who underwent DMEK at 2 tertiary referral centers between 2007 and 2021 (average available follow-up 73 ± 52 months, range 18-174 months) and showed corneal guttae during postoperative examinations were included. Eye bank images were retrospectively reviewed. Occurrence of guttae was observed by specular microscopy in 13 eyes. In 11 cases, presence of guttae was confirmed by confocal microscopy and in 1 case by histology. Five eyes showed an increase in guttae density during the postoperative course. Surgery indications were Fuchs endothelial corneal dystrophy (n = 11), pseudophakic bullous keratopathy (n = 1), and DMEK graft failure after allograft rejection (n = 1); the latter eye had shown no signs of guttae after primary DMEK. Two eyes with guttae required a repeat DMEK due to graft failure. At the last available follow-up, all 11 remaining eyes had clear corneas and 10 eyes had a best-corrected visual acuity of ≥0.9 (decimal). During donor cornea processing in the eye bank, no guttae were observed on the donor tissue. Corneal guttae can occur after DMEK including in eyes operated for indications other than Fuchs endothelial corneal dystrophy and most likely guttae were present on the donor graft but were not detectable by routine slit-lamp and light microscopy evaluation in the eye bank. Postoperative guttae density varies among patients and especially small isolated guttae do not seem to affect clinical outcomes.

Survivability of locally prepared versus imported Descemet membrane endothelial keratoplasty grafts in Edmonton

ObjectifNotre étude visait à évaluer la survie à long terme des greffons décapés sur place ou importés déjà décapés en vue d'une kératoplastie endothéliale de la membrane de Descemet (DMEK, pour Descemet's membrane endothelial keratoplasty) à Edmonton. NatureÉtude de cohorte prospective portant sur des patients qui ont subi une DMEK entre le 1er janvier 2020 et le 31 décembre 2020. ParticipantsTous les patients qui ont fait l'objet d'une DMEK à Edmonton pendant la période à l’étude. MéthodesAinsi, 2 techniciens locaux (Edmonton) ont été formés pour procéder au décapage préalable de greffons. Lorsqu'ils avaient accès à des tissus de donneurs locaux, les greffons étaient préalablement décapés en vue de la DMEK. Dans le cas contraire, on importait des greffons de DMEK déjà décapés auprès de banques de cornées accréditées aux États-Unis. Les caractéristiques des patients et des greffons de même que la survie des greffons ont été évaluées et comparées entre les 2 groupes. RésultatsPendant la période à l’étude, on a utilisé 32 greffons de DMEK prédécapés sur place et 35 greffons de DMEK prédécapés aux États-Unis. Les caractéristiques des donneurs de cornée de même que celles des patients étaient semblables dans les 2 groupes. La meilleure acuité visuelle corrigée s'est améliorée pendant une période pouvant atteindre 6 mois après l'intervention. Elle se chiffrait à 0,2 logMAR dans le groupe de greffons prédécapés localement et à 0,2 logMAR dans le groupe de greffons importés (p = 0,56). Les taux de réinjection postopératoire d'une bulle d'air (rebubbling) s’élevaient à 25 % dans le groupe de greffons décapés localement et à 19 % dans le groupe de greffons importés (p = 0,43). On déplore 1 échec du greffon primaire dans chaque groupe (p = 0,93). La densité des cellules endothéliales a diminué de 37 % dans le groupe de greffons décapés localement et de 33 % dans le groupe de greffons importés selon les mesures réalisées 2 ans après la DMEK. ConclusionsLa survie à long terme des greffons préparés localement est comparable à celle des greffons importés de banques de cornées américaines.

Risk Factors for Descemet Membrane Endothelial Keratoplasty Rejection: Current Perspectives- Systematic Review.

Descemet membrane endothelial keratoplasty (DMEK) is a corneal endothelial transplantation procedure with selective removal of a patient's defective Descemet membrane and endothelium. It is replaced with a healthy donor Descemet membrane and endothelium without a stromal component. Corneal graft rejection can be at the level of epithelium, stroma as well endothelium. DMEK graft rejection is relatively less common than rejection with DSAEK or penetrating keratoplasty, and a good outcome may be achieved with prompt management. The clinical picture of DMEK rejection is usually similar to endothelial rejection in Descemet Stripping Endothelial Keratoplasty (DSEK/DSAEK), which generally manifests as pain, redness, reduction in visual acuity, stromal edema, endothelial rejection line, keratic precipitates at the back of the cornea and corneal neovascularization. However, more subtle forms of rejection or immune reactions are more common in DMEK compared to DSAEK eyes. Early clinical diagnosis, prompt intervention, and meticulous management safeguard visual acuity and graft survival in these cases. Intensive topical steroids form the mainstay in the management of DMEK rejection. Sometimes, oral or intravenous steroids or other systemic immunomodulators may be required. DMEK graft failure can be primary or secondary, and failure usually requires a second procedure in the form of repeat DMEK or DSEK or penetrating keratoplasty (PKP). A detailed literature search was performed using search engines such as Google Scholar, PubMed, and Google books, and a comprehensive review on DMEK rejection was found to be lacking. This review is a comprehensive update on the risk factors, pathophysiology, primary and secondary graft failure, recent advances in diagnosis, prevention of rejection, and updates in the management of DMEK rejection. The review also discusses the differential diagnosis of DMEK failure and rejection, prognosis, and future perspectives considering DMEK failure and rejection.

Effect of Low-Temperature Preservation in Optisol-GS on Preloaded, Endothelium-Out DMEK Grafts.

Three groups of 15 DMEK grafts (five per group) were pre-loaded in the DMEK RAPID Mini and preserved in Optisol-GS for 72 h at different temperatures: group A at >8 °C, group B between 2-8 °C and group C at <2 °C. After stripping and preservation, the viability of the endothelium, cell loss and morphology were assessed through light microscopy following trypan blue and alizarin red staining. Overall mortality was 4.07%, 3.97% and 7.66%, in groups A, B and C, respectively, with percentages of uncovered areas of 0.31%, 1.36% and 0.20% (all p > 0.05). Endothelial cell density variation was 5.51%, 3.06% and 2.82% in groups A, B and C, respectively (p = 0.19). Total Endothelial Cell Loss (ECL) was 4.37%, 5.32% and 7.84% in groups A, B and C, respectively (p = 0.39). Endothelial cell morphology was comparable in all three groups. In the DMEK RAPID Mini, low temperatures (<2 °C) may affect the quality of pre-loaded grafts, inducing a higher ECL after 72 h of preservation, although no significant differences among groups could be proved. Our data would suggest maintaining grafts loaded in the DMEK RAPID Mini at temperatures between 2-8 °C for appropriate preservation.

Descemet membrane endothelial keratoplasty in eyes with glaucoma.

Endothelial keratoplasty has become the standard for the treatment of endothelial dysfunction. In Descemet membrane endothelial keratoplasty (DMEK), only the endothelium and Descemet membrane are transplanted, providing superior outcomes compared to Descemet stripping endothelial keratoplasty (DSEK). A substantial subset of patients who require DMEK have comorbid glaucoma. Even in eyes with complex anterior segment such as eyes with previous trabeculectomy or tube shunts, DMEK can restore meaningful vision and outperforms DSEK in terms of visual recovery, decreased rejection rate, and the need for high dose of topical steroids. However, accelerated endothelial cell loss and secondary graft failure have been described in eyes with previous glaucoma surgery, namely trabeculectomy and drainage device. During DMEK and DSEK procedures, raised intraocular pressure is required to attach the graft, which could worsen preexisting glaucoma or cause de novo glaucoma. Mechanisms of postoperative ocular hypertension include delayed air clearance, pupillary block, steroid response, and damage to angle structures. Medically treated glaucoma has increased risk for postoperative ocular hypertension. By understanding these additional complications and making appropriate modifications in surgical techniques and postoperative management, DMEK can be performed successfully and achieve very good visual outcome in eyes with glaucoma. Such modifications include precisely controlled unfolding technique, iridectomies that can help avoid pupillary block, tube shunts that can be trimmed to facilitate graft unfolding, air fill tension that can be adjusted, and postoperative steroid regimens that can be modified to decrease the risk for steroid response. Long-term survival of the DMEK graft, however, is shorter in eyes with previous glaucoma surgery than those without, as observed after other types of keratoplasty.

Surgical goniolens for tag identification and removal in DMEK surgery.

We describe a novel technique for identifying endothelial Descemet membrane (DM) tags remaining after descemetorhexis in patients undergoing Descemet membrane endothelial keratoplasty (DMEK) surgery. A surgical goniolens is applied to the corneal surface after descemetorhexis in order to visualize the peripheral inner corneal layer at 360° and identify endothelial-DM tags. A detailed visualization of the peripheral inner corneal layer is possible using goniolens, without using any staining in the anterior chamber. The technique may be used to screen the posterior corneal surface for any retained endothelial-DM tags. It may to lower the risk of remaining tags and indirectly lower the incidence of DMEK graft detachment.