Double-Scroll Formation by Fluid Column Manipulation in Preloaded DMEK Grafts Prepared From Younger and Older Donor Tissue.

PURPOSE: The purpose of this study was to determine whether manipulation of preloaded single-scroll Descemet membrane endothelial keratoplasty (DMEK) grafts within the fluid column of an injector can safely and reliably result in formation of double-scroll DMEK grafts and whether there are differential effects on younger versus older donor tissue. METHODS: Pairs of DMEK grafts prepared from older (65-80 years) and younger (48-64 years) donors were preloaded into a Straiko modified Jones tube. One member of the pair was manipulated within the fluid column to form a double-scroll graft, and the other remained unmanipulated. Outcomes measured include success rate for double-scroll formation, endothelial cell loss (ECL), and relative scroll width. RESULTS: Older donor grafts formed double scrolls with a 100% success rate. ECL of older donor manipulated grafts was statistically higher than that of unmanipulated mate grafts (17.4% ± 3.5% vs. 13.0% ± 4.2%, P = 0.03), but was still within the acceptable range for transplant. Younger donor grafts were successfully manipulated into double scrolls with a 67% success rate, and there was no difference in the ECL of manipulated and unmanipulated grafts (15.5% ± 4.4% vs. 13.0% ± 4.5%, P = 0.24). For all grafts and conformations, there was a significant relationship between relative scroll width and ECL ( P < 0.01). CONCLUSIONS: Fluid column manipulation can be used reliably to form double-scroll DMEK grafts. For younger donor grafts, manipulation yields a double scroll without increasing ECL. For older donor grafts, manipulation results in a minimal, acceptable increase in ECL. Surgeons should weigh the advantage of an easily opened graft against the risk of increased ECL when considering this technique.

Examination of a Modified Graft Preparation Technique to Induce Double-Scroll Formation and Promote the Use of Younger Descemet Membrane Endothelial Keratoplasty Donor Tissue.

PURPOSE: The purpose of this study was to determine whether controlled balanced salt solution (BSS) bursts during graft preparation can safely promote formation of a double-scrolled Descemet membrane endothelial keratoplasty (DMEK) graft in younger donor tissue. METHODS: DMEK grafts prepared from young donor tissue (average age, 55 years; range, 39-66 years) were floated in BSS to spontaneously form scrolls (N = 10 pairs). Controlled BSS bursts were used to promote double-scroll (DS) formation in 1 member of each pair. Grafts were stained, preloaded, and shipped before cell viability analysis. After appropriate training, a less experienced technician performed this technique on 10 additional corneas. Outcomes measured for both technicians include the success rate for obtaining a DS, scroll conformation after shipping, and endothelial cell loss (ECL). RESULTS: There was no difference in ECL between grafts subjected to additional manipulation compared with unmanipulated mate grafts (observer 1: 15.2% ± 3.3% vs. 15.2% ± 4.4%, P = 0.99; observer 2: 16.3% ± 2.9% vs. 15.9% ± 4.5%, P = 0.8). A technician experienced with this technique had a 90% success rate, whereas a less experienced technician had a 70% success rate. The mean ECL of the 10 grafts manipulated by the less experienced technician was not significantly different from results obtained from the experienced technician (observer 1: 18.5% ± 6.0% vs. 15.2% ± 3.3%, P = 0.15; observer 2: 18.1% ± 5.6% vs. 16.3% ± 2.9%, P = 0.34). Scrolls maintained their conformation during shipping events. CONCLUSIONS: Double-scroll graft formation using controlled BSS bursts is a reliable technique that can be performed without causing additional damage to DMEK grafts. This technique may make graft unscrolling easier and can promote the use of younger donor tissue for DMEK.

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.

Minimizing Endothelial Cell Loss Caused by Orientation Stamps on Preloaded Descemet Membrane Endothelial Keratoplasty Grafts.

PURPOSE: To quantify endothelial cell loss (ECL) caused by orientation stamps on prestripped and preloaded Descemet membrane endothelial keratoplasty (DMEK) grafts, and to examine a method for reducing ECL using a smaller stamp. METHODS: Ten prestripped and 10 preloaded DMEK grafts were prepared with S-stamps. Ten additional preloaded DMEK grafts were prepared with both an S-stamp and a smaller F-stamp in different paracentral areas of the graft. The footprint of each stamp was measured using ink on cardstock. DMEK grafts were stored in viewing chambers filled with 20 mL of Optisol-GS for 3 days at 4°C. ECL was quantified using Calcein-AM staining and FIJI Weka Segmentation. RESULTS: S-stamps on prestripped DMEK grafts contributed an average ECL of 1.1% ± 0.5% (range: 0.6%-2.2%) toward total graft damage, whereas S-stamps on preloaded DMEK grafts contributed approximately twice that amount (average ECL: 2.0% ± 0.7%, range: 1.3%-3.1%, P = 0.004). Overall ECL for prestripped grafts (average: 7.1% ± 3.3%, range: 3.3%-13.7%) and preloaded grafts (average: 11.3% ± 4.2%, range: 6.9%-19.4%) was similar to previous reports. The footprint of the S-stamp was approximately 45% larger than that of the F-stamp. In 10 preloaded grafts marked with both stamps, the S-stamp caused an average ECL of 1.9% ± 0.6% (range: 1.2%-3.2%), whereas the smaller F-stamp caused an average ECL of 1.0% ± 0.2% (range: 0.8%-1.4%, P = 0.0002). CONCLUSIONS: Loss of endothelial cells associated with graft-stamping was greater in preloaded tissue than in prestripped tissue and was less with a smaller F-stamp than with a larger S-stamp. Using a smaller stamp could help minimize ECL in prestripped and preloaded DMEK grafts.

Measuring Endothelial Cell Loss on DMEK Grafts After Transplantation in Human Cadaveric Whole Eyes: Description of the Technique and Pilot Study.

PURPOSE: To describe a novel method for analyzing Descemet membrane endothelial keratoplasty (DMEK) graft damage after implantation into human cadaveric donor eyes and to compare results achieved by performing DMEK with a surgeon's long-established technique compared with those of an unfamiliar technique. METHODS: Eight DMEK grafts were implanted into previously frozen human cadaveric eyes. Four grafts were implanted using a Straiko injector and tap technique familiar to the surgeon (C.S.S., 3-yr experience), and 4 grafts were implanted using the Tan EndoGlide and "donor mat device" pull-through technique new to the surgeon. After implanting a DMEK graft and attaching it to the recipient stroma with an air bubble tamponade, the corneoscleral cap was "recovered" from the cadaveric globe using standard techniques. The DMEK graft was stained with Calcein-AM. After staining, a 9.5-mm stromal "carrier button" was punched, and the carrier and graft were transferred to a microscope slide. Grafts were imaged and analyzed using FIJI trainable segmentation. RESULTS: Donor graft characteristics were similar between both groups. Grafts implanted using the surgeon's routine technique showed an average endothelial cell loss (ECL) of 31% ± 4% (n = 3). Grafts implanted using the technique unfamiliar to the surgeon showed an average ECL of 47% ± 24%, but with a trend toward improvement (1 = 76%, 2 = 65%, 3 = 32%, 4 = 17% ECL). CONCLUSIONS: Our proof-of-principle experiment shows that this imaging approach enables quantification of ECL caused by different instruments and surgical techniques after graft implantation. We have used this method to visualize the learning curve of 1 surgeon when learning a new surgical technique.

Partitioning an Artificial Anterior Chamber With a Latex Diaphragm to Simulate Anterior and Posterior Segment Pressure Dynamics: The "DMEK Practice Stage," Where Surgeons Can Rehearse the "DMEK Dance".

PURPOSE: To present a novel apparatus for simulating the anterior and posterior segment pressure dynamics involved in executing Descemet membrane endothelial keratoplasty (DMEK) surgery when using a chamber-shallowing technique. METHODS: An artificial anterior chamber (AAC), 18-mm trephine, latex glove, two 3-mL syringes, and one donor cornea comprising an intact corneoscleral cap from which a DMEK tissue was peeled and punched are required for the model. After making the corneal incisions with the corneoscleral cap mounted on the AAC in the usual fashion, the corneoscleral cap is remounted onto the dried AAC over an 18-mm latex diaphragm. The space between the latex diaphragm and the cornea is filled with saline to pressurize the anterior chamber, and the posterior segment is pressurized with air from a syringe. The resulting apparatus comprises a posterior segment and anterior chamber that exert pressure on each other by way of a distensible latex diaphragm. RESULTS: A novice and experienced DMEK surgeon and 2 eye bank technicians were able to assemble the apparatus and perform the routine steps of a DMEK procedure, including maneuvers that require shallowing the anterior chamber and lowering its pressure. Only one cornea was required per apparatus. CONCLUSIONS: We present a novel in vitro model of the human eye that more closely mimics the anterior and posterior segment pressure dynamics of in vivo DMEK surgery than average human and animal cadaveric globes. The model is easy to assemble, inexpensive, and applicable to a range of teaching environments.

Evaluation and Quality Assessment of Prestripped, Preloaded Descemet Membrane Endothelial Keratoplasty Grafts.

PURPOSE: To determine graft quality and feasibility of Descemet membrane endothelial keratoplasty (DMEK) grafts that are prestripped and preloaded into injectors by eye bank technicians before shipping to surgeons. METHODS: DMEK grafts (n = 31) were prepared from donor corneas and preloaded into Straiko Modified Jones tubes and set inside viewing chambers filled with 20 mL of Optisol-GS. Preloaded grafts were evaluated using specular microscopy and slit-lamp biomicroscopy. Endothelial cell loss (ECL) was captured by vital dye staining and quantified using FIJI. A subset of preloaded tissues was subjected to a shipping validation and 5-day storage assay. Fourteen additional DMEK grafts (not preloaded) were examined to quantify damage resulting from prestripping alone. RESULTS: Specular microscopy was able to be performed for all preloaded tissues. Average ECL for preloaded tissues quantified by vital dye staining and FIJI after overnight storage was 16.8% ± 5.9%, and differed from slit-lamp ECL estimation by an average of 5.3% ± 3.6%. The average damage caused by prestripping alone was 9.3% ± 5.9%, and it was significantly less than that of preloaded tissues (P < 0.01). Average ECL for preloaded tissues subjected to round-trip shipping events was 18.5% ± 12.4%, and ECL for tissues stored at 4°C for 5 days after preloading was 13.1% ± 9.5%. CONCLUSIONS: It is possible to prepare, evaluate, and ship DMEK grafts loaded inside a glass carrier and viewing chamber. The ability to evaluate tissues after processing allows for adherence to the Eye Bank Association of America Medical Standards, and for surgeons to receive the most accurate tissue information.

Review of the poster "Dosimetric comparison of gamma knife radiosurgery vs. 125I plaque brachytherapy in a cohort of choroidal melanomas".

Historically, treatment for choroidal melanomas was surgical enucleation. Currently, treatment methods such as stereotactic radiosurgery and brachytherapy are being used to spare the eye. The poster "Dosimetric Comparison of Gamma Knife Radiosurgery vs. I-125 Plaque Brachytherapy in a Cohort of Choroidal Melanomas" presented at ASTRO 2007 by Anderson et al. provides a comparison of these methods. The dose to disk, fovea and lens in 29 patients from a simulated I-125 treatment and a delivered Gamma Knife radiosurgery was compared. Thirty Gy was prescribed to the 50% Isodose line in the radiosurgery and 85 Gy was prescribed to the apex of the tumor in the I-125 simulation. It was found that the Gamma Knife spares the disk better in 59% of the tumors, including those >or=6.5 mm in height; spares the fovea better in 69% of the tumors, including those >or=5.5 mm; and spares lens better in only 30% of the tumors, with no distinction in size. Tumor location was not taken into account for this study, which could explain the variations in smaller tumors. For larger tumors, gamma knife will protect most organs at risk more effectively. This study shows how a tumor's parameters can be used in selecting treatment modality.