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

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

PURPOSE

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.

METHODS

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 120 s in either a plastic or glass medium prior to delivery into the recipient's eye. The ECL was compared between the two groups 12-30 months post-operatively.

RESULTS

ECL at 12-30 months 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.

CONCLUSION

Staining of the DMEK graft in a plastic medium caused less ECL compared to the glass medium.

Size and Shape Matter: Cell Viability of Preloaded Descemet Stripping Automated Endothelial Keratoplasty Grafts in Three Different Carriers

PURPOSE

The aim of this study was to examine endothelial cell loss (ECL) associated with preloaded Descemet stripping automated endothelial keratoplasty (DSAEK) grafts loaded into 3 carriers of different size and shape.

METHODS

Thirty-six donor corneas were prepared for DSAEK and loaded into an EndoGlide Ultrathin (control) (2.0 mm × 3.5 mm lumen, 4.5 mm/4.9 mm incision for scleral tunnel/clear corneal insertion), Descemet membrane endothelial keratoplasty EndoGlide (experimental) (1.1 mm × 1.7 mm lumen, 2.65 mm incision), or round glass Jones tube (experimental) (1.8 mm lumen, 3.0 mm incision). Control grafts were stored for 6 days in Optisol-GS and experimental grafts stored for 24 hours in Life4C before analysis using Calcein AM staining. Grafts were imaged and ECL was analyzed by FIJI segmentation. The statistical significance of ECL was determined using 1-way ANOVA and Tukey post hoc analysis.

RESULTS

There were no significant differences in donor characteristics for grafts in each cohort. ECL for grafts loaded into the EndoGlide Ultrathin was 10.3% ± 2.3% (graft thickness: 60-189 μm, n = 9). ECL for grafts loaded into the Descemet membrane endothelial keratoplasty EndoGlide was 22.2% ± 7.1% (graft thickness: 38-63 μm, n = 9). ECL for thin grafts (34-60 μm, n = 9) loaded into the Jones tube was 24.0% ± 5.0%. ECL for thick grafts (92-119 μm, n = 9) loaded into the Jones tube was 34.2% ± 6.1% ECL ( P < 0.001). Combined regression analysis revealed that graft thickness is directly correlated to ECL ( P < 0.01).

CONCLUSIONS

The size and shape of the carrier can influence the cell viability of preloaded DSAEK grafts. Compared with a larger carrier, smaller lumen carriers are associated with greater ECL. In smaller lumen carriers, ECL increases with increasing DSAEK graft thickness.

DMEK surgical training: An instructional guide on various wet-lab methods

Descemet membrane endothelial keratoplasty (DMEK) is a partial-thickness corneal transplantation procedure that involves selective transplantation of the Descemet membrane and endothelium. DMEK offers significant advantages over other keratoplasty techniques, such as faster visual rehabilitation, better final visual acuity due to minimal optical interface effects, lower risk of allograft rejection, and less long-term dependence on topical steroids. Despite all its advantages, DMEK has been found to be more challenging than other corneal transplantation techniques, and its steep learning curve appears to be an obstacle to its widespread use and adoption by corneal surgeons worldwide. DMEK surgical training laboratories (wet labs) provide a window of opportunity for surgeons to learn, prepare, manipulate, and deliver these grafts in a risk-free environment. Wet labs are a significant learning tool, especially for those institutions that have limited tissue availability in their local centers. We provide a step-by-step guide for preparing DMEK grafts using different techniques on human and nonhuman models with instructional videos. This article should eventually help the trainees and the educators understand the requirements for performing DMEK and conducting a DMEK wet lab and develop their skills and interests from a wide variety of available techniques.

Intraoperative optical coherence tomography-guided nanothin Descemet stripping automated endothelial keratoplasty in a patient with a remarkably thickened cornea

Purpose

To report use of intraoperative optical coherence tomography (OCT) for nanothin Descemet stripping automated endothelial keratoplasty (DSAEK) in a patient with an extremely thickened cornea due to advanced bullous keratopathy.

Observations

A 90-year-old woman with a history of multiple trabeculectomies was referred to us for treatment of advanced bullous keratopathy (1400 μm central corneal thickness). Nanothin DSAEK was planned and performed. In brief, after the removal of the loose corneal epithelium, the anterior chamber was meticulously observed using a surgical microscope and oblique light via an endoillumination probe; however, the visibility of the anterior chamber was limited because of severe corneal edema. Subsequently, a nanothin (47 μm) DSAEK graft stained with trypan blue was inserted into the anterior chamber using an NS endoinserter. Intraoperative OCT was used successfully to visualize the graft unfolding, air tamponade, and graft attachment. At 3 months postoperatively, significant corneal clearing (625 μm central corneal thickness), improvement of visual acuity (decimal 0.04), and pain relief were obtained.

Conclusions and importance

Intraoperative OCT is useful for nanothin DSAEK even when the surgical microscope view is compromised by a remarkably thickened host cornea due to advanced bullous keratopathy. As an alternative to a penetrating keratoplasty, less invasive nanothin DSAEK was successfully performed.

Marking DMEK Grafts Using Bandage Contact Lens Interface Technique: Doubling the Utilization During the Acute Shortage of Donor Corneas

PURPOSE

The purpose of this study was to describe a novel bandage contact lens (BCL) interface technique for marking the Descemet membrane endothelial keratoplasty (DMEK) graft so that a single donor cornea can be used effectively for 2 recipients during acute shortage.

METHODS

This was a retrospective comparative case series. In group A, 37 eyes underwent DMEK using a graft marked by the [DOUBLE HIGH-REVERSED-9 QUOTATION MARK]BCL interface technique" that was compared with 49 conventional DMEK grafts marked through the stromal window (group B). In group A, a resized BCL with a central 3-mm hole with the concavity up was placed between the stroma and peeled-off DM. This BCL with DM was flipped for S-stamping on the DM side. Final trephination was performed on a second Teflon block. The remaining anterior lamellar tissues of group A were used on the same day for other keratoplasty procedures. Endothelial cell density (ECD) and endothelial cell loss between the 2 groups were compared after 3 and 6 months.

RESULTS

The ECD at 3 months in group A (n = 35) versus group B (n = 45) was 2228 ± 270/mm2 versus 2302 ± 254/mm2 (P = 0.48), and the ECD at 6 months (n = 23 and 22) was 2058 ± 324/mm2 versus 2118 ± 260/mm2 (P = 0.72). The corresponding endothelial cell loss was 23.3% ± 6.8% versus 20.3% ± 6.1% (P = 0.18) at 3 months and 29.1% ± 8.4% versus 26.7% ± 8.0% (P = 0.34) at 6 months. Among anterior tissues of group A, 17 (45.9%) were used for deep anterior lamellar keratoplasty, 18 (48.6%) were used for larger therapeutic and tectonic grafts, and 2 were used as keratoprosthesis carriers. Donor detachment rate (8.6% vs. 8.9%) was similar in both groups without primary graft failures.

CONCLUSIONS

The BCL interface technique is a simple and safe technique for stamping DMEK grafts. Anterior corneal tissues can be used for additional keratoplasties during donor shortage.

Modified procedure for Loading "Flat" DMEK Grafts Into an Injector

PURPOSE

The aim of this study was to determine whether loading a Descemet membrane endothelial keratoplasty (DMEK) graft using a drop-in procedure results in more endothelial cell loss (ECL) than the standard suction procedure.

METHODS

Pairs of donor corneas with equivalent preprocessing endothelium were prepared using the standard protocol of our eye bank. One member of each pair was loaded into an injector using the standard suction protocol. The mate graft was loaded using a drop-in protocol, in which the edge of the graft was gently grasped with a forceps, lifted to the edge of the injector, and dropped inside. Grafts were evaluated for ECL and examined for grab marks or other loading-associated damage.

RESULTS

There was no difference in mean ECL of grafts prepared for DMEK using the standard protocol (20.6% ± 4.5%) compared with that of mate grafts prepared using the drop-in loading protocol (19.5% ± 4.8%, P = 0.59). There was no consistent pattern of damage in the drop-in-loaded grafts, as grab marks or other tissue damage associated with the drop-in loading protocol were not consistently identified by a trained corneal surgeon.

CONCLUSIONS

ECL was not significantly different in grafts prepared using a drop-in loading procedure compared with grafts prepared using the standard suction protocol. The drop-in loading protocol may be particularly useful to surgeons who load their own grafts and eye bank processing technicians who encounter a "flat" DMEK graft that does not scroll or a loosely scrolled DMEK graft.

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.

Cost-effectiveness analysis of preloaded versus non-preloaded Descemet membrane endothelial keratoplasty for the treatment of Fuchs endothelial corneal dystrophy in an academic centre

AIMS

To determine the cost-effectiveness of preloaded Descemet membrane endothelial keratoplasty (pDMEK) versus non-preloaded DMEK (n-pDMEK) for the treatment of Fuchs endothelial corneal dystrophy (FECD).

METHODS

From a societal and healthcare perspective, this retrospective cost-effectiveness analysis analysed a cohort of 58 patients with FECD receiving pDMEK (n=38) or n-pDMEK (n=30) from 2016 to 2018 in the Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, USA. Exclusion criteria were previous ocular surgeries (other than uncomplicated cataract surgery), including other keratoplasty procedures, ocular pathological conditions as glaucoma, amblyopia, laser treatments, or any retinal or corneal disease. The main outcome parameters were the incremental cost-utility ratio (ICUR) and net monetary benefit (NMB).

RESULTS

pDMEK was less costly compared with n-pDMEK (healthcare: $13 886 vs $15 329; societal: $20 805 vs $22 262), with a slighter greater utility (QALY 0.6682 vs QALY 0.6640) over a time horizon of 15 years. pDMEK offered a slightly higher clinical effectiveness (+0.0042 QALY/patient) at a lower cost (healthcare: -$1444 per patient; societal: -$1457 per patient) in improving visual acuity in this cohort of patients with FECD. pDMEK achieved a favourable ICUR and NMB compared with n-pDMEK. Based on sensitivity analyses performed, the economic model was robust.

CONCLUSIONS

From the societal and healthcare perspective, pDMEK was less costly and generated comparable utility values relative to n-pDMEK. Therefore, pDMEK appears to be cost-effective and cost saving with respect to n-pDMEK. Further long-term follow-up data are needed to confirm these findings.

Graft Edge Reflection of a Tightly Scrolled Roll Using Endoillumination as a Simple Method for Determining Graft Orientation in Descemet Membrane Endothelial Keratoplasty

PURPOSE

To describe a simple finding that can be used to determine donor tissue orientation in Descemet membrane endothelial keratoplasty (DMEK). This involves the appearance of a highly reflective round curved line from an overlapping graft edge within the anterior chamber using light from an endoilluminator. We here name this Kobayashi sign (K-sign).

METHODS

Twelve consecutive eyes from 12 patients who underwent DMEK were evaluated for the presence of a K-sign. The presence of Berrospi sign (B-sign), a double-line reflection from the peripheral curls of the Descemet membrane (DM) roll that has been reported to be useful for correct graft orientation, was also evaluated.

RESULTS

Of 12 cases, 3 donors showed a loosely scrolled roll soon after DM donor insertion; all 3 of these showed a positive B-sign only when the endoilluminator was used. Nine donors showed a tightly scrolled DM roll without a B-sign; among these 9 donors, a K-sign was visible in 7 cases only when the endoilluminator was used. The remaining 2 cases with a tight scroll configuration showed no K-sign even with the use of endoillumination, indicating that the roll edge was located completely downward; rotation of the roll using a small jet of fluid from paracentesis revealed K-sign in these cases.

CONCLUSIONS

This technique is useful for determining the correct orientation of a tightly scrolled DM roll, subsequently enabling rapid DMEK surgery. For loosely scrolled DM roll, endoillumination enhanced B-sing is proven useful.

One-Year Clinical Outcomes of Preloaded Descemet Membrane Endothelial Keratoplasty Versus Non-Preloaded Descemet Membrane Endothelial Keratoplasty

PURPOSE

To compare the one-year outcomes of preloaded Descemet membrane endothelial keratoplasty (pDMEK) and non-preloaded DMEK (n-pDMEK) in patients with Fuchs endothelial corneal dystrophy (FECD).

METHODS

This retrospective comparative cohort study consecutively included 68 eyes with Fuchs endothelial corneal dystrophy who underwent either pDMEK (n = 38) or n-pDMEK (n = 30) performed by cornea fellows with an experienced surgeon between 2016 and 2018 at the Massachusetts Eye and Ear Infirmary. Exclusion criteria were previous surgery (other than uncomplicated cataract surgery) and any documented evidence of macular or other corneal diseases. Corrected distance visual acuity (CDVA), central corneal thickness, intraocular pressure, patient characteristics, postprocessing endothelial cell count, donor graft data, and complications were compared.

RESULTS

CDVA showed similar results for pDMEK (0.12 ± 0.11 logarithm of the minimal angle of resolution [LogMAR]) and n-pDMEK (0.13 ± 0.13 LogMAR) (P = 0.827). Sixty-six percent of the pDMEK eyes and 57% of the n-pDMEK eyes achieved a VA of ≥0.1 LogMAR, and 95% and 97%, respectively, achieved a CDVA ≥0.3 LogMAR. The preoperative central corneal thickness of pDMEK and n-pDMEK (644 ± 62.2 μm, 660.5 ± 56.2 μm) decreased significantly after surgery (525.1 ± 43.6 μm, 526.5 ± 45.2 μm, P < 0.001), with no difference between groups (P = 0.840). The postprocessing endothelial cell count did not differ between pDMEK (2959.2 ± 182.9 cells/mm2) and n-pDMEK (2939.3 ± 278.7 cells/mm2) (P = 0.484). Complication rates were comparable with just the rebubbling performed in a minor procedure room showing a lower rate for pDMEK (13.16%) compared with n-pDMEK (33.33%) (P < 0.045).

CONCLUSIONS

One-year clinical outcomes were similar between pDMEK and n-pDMEK procedures, rendering eye bank-prepared pDMEK tissues a useful tool in the treatment of endothelial dysfunction.

Intraoperative Optical Coherence Tomography-Assisted Descemet Membrane Endothelial Keratoplasty in the DISCOVER Study: First 100 Cases

PURPOSE

Intraoperative optical coherence tomography (iOCT) may facilitate successful transition to Descemet membrane endothelial keratoplasty (DMEK) surgery via improved efficiency of tissue orientation. The purpose of this study is to report a large consecutive series of iOCT-assisted DMEK, inclusive of all learning curve cases.

DESIGN

Prospective consecutive case series.

METHODS

The Determination of Feasibility of Intraoperative Spectral Domain Microscope Combined/Integrated OCT Visualization During En Face Retinal and Ophthalmic Surgery (DISCOVER) study is a single-site, multisurgeon, IRB-approved investigational device prospective study. The first 100 consecutive iOCT-assisted DMEK surgeries performed by 1 attending corneal surgeon (JMG) and 6 novice surgeons (cornea fellows under supervision) were reviewed. iOCT was utilized for tissue orientation. Patient demographics, tissue characteristics, intraoperative parameters, and postoperative complications are reported.

OUTCOMES

(1) Utility of iOCT based on surgeon reporting during surgery, (2) intraoperative graft unscrolling efficiency, and (3) frequency of postoperative complications.

RESULTS

One hundred eyes of 76 patients were enrolled. Forty-three cases were performed by 1 staff physician and 57 cases were performed by 6 cornea fellows. Concurrent phacoemulsification with lens implantation was performed in 52 cases (52%). Nine eyes (9%) required rebubbling. Two eyes (2.0%) experienced primary graft failure. One graft failure resulted from surgeon error in interpreting the iOCT. Average unscrolling time was 4.4 ± 4.1 minutes (range: 0.7-27.6 minutes).

CONCLUSIONS

iOCT facilitates DMEK orientation without the need for external markings. For novice DMEK surgeons, complication rates and unscrolling times compare favorably with alternative tissue orientation methods.

How to Avoid an Upside-Down Orientation of the Graft during Descemet Membrane Endothelial Keratoplasty?

Purpose

Incorrect anterior-posterior orientation of the Descemet endothelial complex (DEC) is one of the causes of failure of Descemet membrane endothelial keratoplasty (DMEK). We evaluated a new marking technique to avoid such a misorientation.

Method

A new marking technique of the DEC was evaluated in patients requiring primary DMEK. A Braille-“R”-letter was applied dot by dot onto the stromal surface of the DEC after lifting it by injecting an air-bubble into the interface between the endothelial surface of the partially stripped graft. The positioning of the graft was intraoperatively controlled by an orientation of the Braille-“R”-letter. Laboratory tests were conducted to test the impact of the marking technique on endothelial cell count.

Results

We included prospectively 37 eyes of 30 patients. Four eyes were phakic and 33 pseudophakic. Five grafts (14%) presented an undifferentiated rolling tendency in the anterior chamber, and evaluation of their positioning was possible due to orientation of the mark alone. In case of an upside-down orientation, grafts were flipped immediately. A correct orientation of the graft was achieved in all cases at the end of the surgery. The endothelial cell loss due to the mark was estimated to be less than 0.3%. At 3- and 6-month follow-ups, the mean best-corrected visual acuity was 0.21 ± 0.15 and 0.15 ± 0.11 logMAR, respectively, and endothelial cell density was 1661 ± 349 and 1618 ± 396 cells/mm², respectively. Only one patient (3%) needed re-bubbling.

Conclusions

To rely on the natural rolling tendency of the graft alone does not assure its correct positioning in all cases. Creation of the mark with 4 dots punctuated on the air-lifted stromal side of the DEC is a simple and endothelial cell saving marking method to ensure correct orientation of the graft during DMEK.

Patent Blue V as an Alternative Stain for DMEK Grafts: Safety, Stain Retention, and Feasibility

PURPOSE

To determine whether Patent Blue V (PB) can be used as an alternative dye for staining Descemet membrane endothelial keratoplasty (DMEK) grafts.

METHODS

DMEK grafts from donor corneas were stained with 2.5% PB for 4 minutes (n = 2), 2.5% PB for 10 minutes (n = 2), or 0.06% trypan blue (TB) for 4 minutes (n = 1). The stain intensity of the grafts was compared initially and at different time points over a 15-minute period of balanced salt solution wash using a grading scale based on a serial dilution series of PB. Three additional grafts were stained with 2.5% PB for 10 minutes and used in mock surgeries to assess stain retention after injection and manipulation in a donor eye model for 25 minutes. To assess the safety of PB, DMEK grafts were prepared from 10 pairs of corneas where one cornea was stained with 0.06% TB for 4 minutes and the mate cornea was stained with 2.5% PB for 10 minutes. The grafts were preloaded and stored for 5 days in Optisol-GS at 2°C to 8°C, and endothelial cell loss was quantified using Calcein-AM staining and FIJI segmentation by 2 masked readers.

RESULTS

PB stain intensities were lighter than TB-stained grafts. Grafts stained with 2.5% PB for 10 minutes retained sufficient color for the 25-minute duration of mock surgery. The average endothelial cell loss for PB versus TB grafts was 21.6% ± 5.3% versus 20.2% ± 5.4% (P = 0.202) as determined by reader 1 and 23.6% ± 4.8% versus 21.2% ± 5.8% (P = 0.092) as determined by reader 2.

CONCLUSIONS

PB is a viable alternative dye in DMEK grafts for applications where TB may not be available or approved for use.