The S-stamp in Descemet Membrane Endothelial Keratoplasty Safely Eliminates Upside-down Graft Implantation.

PURPOSE: To present 6-month clinical outcomes from a series of 165 consecutive Descemet membrane endothelial keratoplasty (DMEK) procedures before and after the introduction of a novel stromal-sided S-stamp preparation technique that has decreased the incidence of iatrogenic primary graft failure by eliminating upside-down grafts. DESIGN: Retrospective nonrandomized comparative case series. PARTICIPANTS: We included 165 consecutive eyes that had undergone DMEK surgery for Fuchs' or pseudophakic bullous keratopathy. These cases were divided into 2 cohorts: the first cohort comprised 31 cases that used unstamped tissue before the S-stamp was introduced, and the second cohort comprised 133 cases after the S-stamp was incorporated into the standardized technique. A single unstamped DMEK case was performed after the introduction of the S-stamp for a total of 32 unstamped cases. METHODS: Donor materials were prepared at a single eye bank using a standardized technique, which subsequently incorporated the addition of a dry ink gentian violet S-stamp to the stromal side of Descemet membrane. All surgeries were performed at a single clinical site by 5 surgeons (2 attending surgeons and 3 fellows). Two of the 165 DMEK cases were performed for pseudophakic bullous keratopathy (2 cases, 1 in each cohort), and the remaining cases were for Fuchs' endothelial dystrophy. Primary outcome measures were assessed at 6 months and maintained in a prospective institutional review board-approved study. MAIN OUTCOME MEASURES: We analyzed the 6-month endothelial cell density, incidence of iatrogenic primary graft failure, upside-down graft implantation, and rebubble events. RESULTS: The S-stamp eliminated upside-down graft implantations (0/133 S-stamped vs 3/32 unstamped) and did not significantly alter 6-month endothelial cell loss (31±17% S-stamped vs 29±14% unstamped; P = 0.62) or frequency of rebubble (17/133 S-stamped vs 1/32 unstamped; P = 0.20). CONCLUSION: The incorporation of a stromal-sided S-stamp eliminates iatrogenic primary graft failure owing to upside-down implantation of DMEK grafts, without adversely affecting early postoperative complications or 6-month endothelial cell loss.

Prospective In Vitro Comparison of Kerasave and Optisol-GS Corneal Storage Solutions.

PURPOSE: The aim of this study was to compare the performance of Kerasave and Optisol-GS for hypothermic corneal storage for 14 days. METHODS: This study was a prospective laboratory investigation. Mate corneas were recovered into Kerasave or Optisol-GS (27 pairs) and stored at 2°C to 8°C for 14 days. Corneas were evaluated by trained eye bank technicians, and study parameters were compared between the initial and final evaluations. Endothelial cell density (ECD), hexagonality (HEX), and coefficient of variation (CV) were evaluated by specular microscopy, and central corneal thickness (CCT) was examined by optical coherence tomography after 1, 3, 7, and 14 days of storage. Corneal transparency was scored using slit lamp examination at days 1 and 14. RESULTS: Average ECD, HEX, and CV for the Kerasave (2653 ± 303 cells/mm 2 , 57 ± 4%, and 36 ± 3%) and Optisol-GS (2623 ± 306 cells/mm 2 , 57 ± 5%, and 36 ± 4%) groups were not significantly different at day 1. There was also no difference at any other study time points (all P > 0.05). ECD did not significantly change from day 1 to day 14 in either group ( P > 0.05), but a statistically significant change in HEX and CV was observed between day 1 and day 14 in both groups ( P < 0.01). Average CCT measured at day 1 for corneas stored in Kerasave was 622 ± 49 µm and those stored in Optisol-GS was 580 ± 35 µm ( P < 0.01). The difference in CCT measurements was not significantly different at day 14 (Kerasave: 674 ± 46 µm vs. Optisol-GS: 647 ± 58 µm, P > 0.05). Corneal transparency was not significantly different between the 2 groups at day 1 or day 14. CONCLUSIONS: The corneal quality and clinically relevant parameters including ECD, endothelial morphometry, and corneal transparency were not different in corneas stored in Kerasave or Optisol-GS for 14 days. The initial difference in CCT between the 2 groups decreased at day 14. These results demonstrated that Kerasave corneal storage solution preserves the corneal endothelium similarly to Optisol-GS.

Ink Retention and Endothelial Cell Viability After the Application of an Orientation Stamp Over an Air Bubble During Descemet Membrane Endothelial Keratoplasty Graft Preparation.

PURPOSE: To investigate stamp visibility and endothelial cell loss (ECL) after the application of an orientation mark to Descemet membrane endothelial keratoplasty (DMEK) grafts supported by an air bubble. METHODS: Eighteen DMEK grafts were prepared at an eye bank using a technique where an orientation mark was applied to the stromal surface of a DMEK graft that was supported by a small air bubble placed at the edge of the 2 endothelial surfaces of the graft. Grafts were evaluated at 2 and 5 days for stamp visibility and at 5 days with calcein-AM staining for ECL. Nine grafts underwent cross-country shipping, and the ECL of shipped and nonshipped grafts was compared using unpaired t test. RESULTS: All 18 DMEK grafts exhibited a single, solid, readily visible orientation mark 2 and 5 days after preparation with a mean ECL of 13.5% ± 4.9%. Shipping conditions had no effect on stain retention or ECL. CONCLUSIONS: The application of an orientation stamp to a DMEK graft over an air bubble in an eye bank setting results in a single, solid orientation mark that is readily visible within the period in which most eye bank-prepared tissue is used. This technique produces no further ECL compared with the methods where the orientation stamp is applied through a stromal window. Eye bank technicians and surgeons can be confident that this modified preparation technique results in transplant-quality DMEK grafts with the additional benefit of conserving the stromal cap for use in other anterior lamellar procedures, thereby making efficient use of donor tissue.

Optical Coherence Tomography Assessment of the Cornea During Corneal Swelling: Should the Term "Descemet Membrane Folds" Be Reconsidered?

PURPOSE: Previous work has suggested that Descemet membrane (DM) folds arise in response to corneal swelling. However, their origin has not been closely explored. In this study, we used optical coherence tomography to evaluate whether DM folds arise secondary to folds in the middle stroma. METHODS: Serial optical coherence tomography images of donor cornea pairs in deionized water were taken for each of the following corneal manipulations: 1) untreated, 2) DM and the endothelium removed, 3) excised in the region of the deep middle/posterior stroma, and 4) excised in the middle stroma. RESULTS: For intact corneas, increasing duration in deionized water was marked by a progressive increase in corneal thickness and number of folds along the posterior surface. With DM and the endothelium removed, a similar phenomenon was observed. In the third set of corneas, the plane of resection created a structural separation in the region of the deep middle/posterior stroma. Folds were seen originating anterior to the resection plane. For corneas with the posterior and part of the middle stroma removed, the typical folds on the posterior surface as seen in the previous conditions were not observed. Instead, less numerous and smaller irregularities of the posterior surface of the resection plane were present. CONCLUSIONS: Folds in DM associated with corneal edema originate in the middle and posterior stroma and are secondarily transmitted into DM. On the basis of the stromal origin of these anatomic changes, "stromal folds" should be considered a more accurate term to replace "Descemet membrane folds."

Eye Bank-Prepared Femtosecond Laser-Assisted Automated Descemet Membrane Endothelial Grafts.

PURPOSE: The aim of this study was to investigate the use of a femtosecond laser (FL) in the eye bank preparation of corneas for Descemet membrane (DM) automated endothelial keratoplasty (fDMAEK) and to compare endothelial cell death in graft preparations between fDMAEK, Descemet stripping endothelial keratoplasty (DSEK), and DM endothelial keratoplasty (DMEK). METHODS: Twenty cadaveric tissues were used to test the fDMAEK method. A 9.0-mm-diameter lamellar incision was made using the FL with a 6.0-mm perpendicular anterior ring cut that enabled a stromal rim by acting as a venting incision for bubble expansion. DM was pneumodissected off the central 6.0 mm of the tissue. The fDMAEK grafts were trephined and stained with a viability dye, calcein AM. The entire stained endothelial surface was digitally captured and the endothelial cell loss (ECL) was calculated using trainable segmentation software. For comparison, a series of 6 DSEK grafts and 8 DMEK grafts were created and analyzed. RESULTS: Six of 20 tissues (30%) were lost during fDMAEK preparation. In the 14 successful tissues, the average ECL was 30.4% [95% confidence interval (CI), 25.3-35.6] compared with 21.1% (95% CI, 13.2-28.9, P = 0.09) in the 6 DSEK grafts and 22.5% (95% CI, 18.0-27.0, P = 0.04) in the 8 DMEK grafts. CONCLUSIONS: FLs are useful in preparing DMAEK tissue at the eye bank and may promote predictable and precise big bubbles and stromal rims. The fDMAEK preparation success improved with experience and laser adjustments. In fDMAEK, the ECL is higher than was previously reported in DMEK and DSEK, likely due to greater tissue manipulation, although not significantly higher than DSEK controls.

Risk factors for eye bank preparation failure of Descemet membrane endothelial keratoplasty tissue.

PURPOSE: To assess the results of a single eye bank preparing a high volume of Descemet membrane endothelial keratoplasty (DMEK) tissues using multiple technicians to provide an overview of the experience and to identify possible risk factors for DMEK preparation failure. DESIGN: Cross-sectional study. METHODS: setting: Lions VisionGift and Wilmer Eye Institute at Johns Hopkins Hospital. STUDY POPULATION: All 563 corneal tissues processed by technicians at Lions VisionGift for DMEK between October 2011 and May 2014 inclusive. OBSERVATION PROCEDURES: Tissues were divided into 2 groups: DMEK preparation success and DMEK preparation failure. MAIN OUTCOME MEASURES: We compared donor characteristics, including past medical history. RESULTS: The overall tissue preparation failure rate was 5.2%. Univariate analysis showed diabetes mellitus (P = .000028) and its duration (P = .023), hypertension (P = .021), and hyperlipidemia or obesity (P = .0004) were more common in the failure group. Multivariate analysis showed diabetes mellitus (P = .0001) and hyperlipidemia or obesity (P = .0142) were more common in the failure group. Elimination of tissues from donors either with diabetes or with hyperlipidemia or obesity reduced the failure rate from 5.2% to 2.2%. Trends toward lower failure rates occurring with increased technician experience also were found. CONCLUSIONS: Our work showed that tissues from donors with diabetes mellitus (especially with longer disease duration) and hyperlipidemia or obesity were associated with higher failure rates in DMEK preparation. Elimination of tissues from donors either with diabetes mellitus or with hyperlipidemia or obesity reduced the failure rate. In addition, our data may provide useful initial guidelines and benchmark values for eye banks seeking to establish and maintain DMEK programs.