Comparison of preservation and transportation protocols for preloaded Descemet membrane endothelial keratoplasty

Mechanical, optical, chemical, and biological evaluations of fish scale-derived scaffold for corneal replacements: A systematic review

Corneal blindness is commonly treated through corneal replacement with allogeneic corneal donors, which may face shortage. Regarding this issue, xenogeneic alternatives are explored. Fish scale-derived scaffolds (FSSs) are among the alternatives due to the lower risk of infection and abundant sources of raw materials. Unfortunately, the information about mechanical, optical, chemical, and biological performances of FSSs for corneal replacements is still scattered, as well as about the fabrication techniques. This study aims to gather scattered pieces of information about the mentioned performances and fabrication techniques of FSSs for corneal replacements. Sorted from four scientific databases and using the PRISMA checklist, eleven relevant articles are collected. FSSs are commonly fabricated using decellularization and decalcification processes, generating FSSs with parallel multilayers or crossed fibers with topographic microchannels. In the collected studies, similar mechanical properties of FSSs to native tissues are discovered, as well as good transparency, light remittance, but poorer refractive indexes than native tissues. Biological evaluations mostly discuss histology, cell proliferations, and immune responses on FSSs, while only a few studies examine the vascularization. No studies completed comprehensive evaluations on the four properties. The current progress of FSS developments demonstrates the potential of FSS use for corneal replacements.

Quality assurance in corneal transplants: Donor cornea assessment and oversight

The cornea is the most frequently transplanted human tissue, and corneal transplantation represents the most successful allogeneic transplant worldwide. In order to obtain good surgical outcome and visual rehabilitation and to ensure the safety of the recipient, accurate screening of donors and donor tissues is necessary throughout the process. This mitigates the risks of transmission to the recipient, including infectious diseases and environmental contaminants, and ensures high optical and functional quality of the tissues. The process can be divided into 3 stages: (1) donor evaluation and selection before tissue harvest performed by the retrieval team, (2) tissue analysis during the storage phase conducted by the eye bank technicians after the retrieval, and, (3) tissue quality checks undertaken by the surgeons in the operating room before transplantation. Although process improvements over the years have greatly enhanced safety, quality, and outcome of the corneal transplants, a lack of standardization between centers during certain phases of the process still remains, and may impact on the quality and number of transplanted corneas. Here we detail the donor screening process for the retrieval teams, eye bank operators. and ophthalmic surgeons and examine the limitations associated with each of these stages.

Validation of preloaded DMEK donor tissues: a laboratory-based study on endothelial cell viability and comparison of two F-mark inks

OBJECTIVE

To investigate endothelial cell loss (ECL) associated with Descemet membrane endothelial keratoplasty (DMEK) donor tissues preloaded in the DMEK RAPID transport system after 1 and 5 days and to compare prestamping with 2 different F-mark inks.

METHODS

DMEK donor tissues were stripped, marked with gentian violet dye applied as an F-mark, trephined, stained with trypan blue, and then preloaded into the DMEK RAPID transport system by an eye bank technician. Preloaded DMEK tissues were then unfolded and stained with calcein AM after 1 or 5 days of storage. Tissues were imaged, analyzed for total tissue ECL, and immunostained for corneal endothelium markers zonular occludens-1 and xCD166. Additionally, ECL and the intensity of an F-mark caused by 2 different inks were quantified.

RESULTS

Preloaded DMEK tissues displayed an average ECL of 11.9% ± 4.5% (n = 8) at 1 day and 9.9% ± 4.2% (n = 9) at 5 days. No difference was found between the 2 groups. Zonular occludens-1 and activated leukocyte cell adhesion molecule (ALCAM; also know as CD166) staining showed that the corneal endothelial monolayer remained intact on preloaded tissues. On 5-day preloaded DMEK tissues, the average ECL and mean grayscale caused by the Keir Surgical ink F-mark and the Cardinal Health ink F-mark were 4.3% ± 0.8% and 158.5 ± 13.9% and 5.0% ± 1.1% and 142.9% ± 20.0%, respectively. No difference was found between the F-mark inks.

CONCLUSION

Preloaded DMEK donor tissues resulted in an acceptable ECL range after 1 and 5 days of storage and were deemed suitable for transplantation. Both F-mark inks are acceptable for prestamping preloaded DMEK tissues prior to surgical transplantation with comparable ECL and intensities.

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.

Combined or sequential DMEK in cases of cataract and Fuchs endothelial corneal dystrophy-A systematic review and meta-analysis

To compare the outcomes of Descemet membrane endothelial keratoplasty (DMEK) performed after phacoemulsification and intraocular lens (IOL) implantation (sequential DMEK) and DMEK combined with phacoemulsification and IOL implantation (combined DMEK) in patients with Fuchs endothelial corneal dystrophy (FECD) and cataract. Systematic literature review and meta-analysis performed according to the PRISMA guidelines and registered in PROSPERO. Literature searches were conducted in Medline and Scopus. Comparative studies reporting sequential DMEK and combined DMEK in FECD patients were included. The main outcome measure of the study was the corrected distance visual acuity (CDVA) improvement. Secondary outcomes were postoperative endothelial cell density (ECD), rebubbling rate and primary graft failure rate. Bias risk was assessed and a quality appraisal of the body of evidence was completed using the Cochrane Robin-I tool. A total of 667 eyes (5 studies) were included in this review, 292 eyes (43.77%) underwent a combined DMEK, while 375 (56.22%) eyes underwent a sequential DMEK surgery. We found no evidence of a difference between the two groups (mean difference, 95% CI) regarding: (1) CDVA improvement (-0.06; -0.14, 0.03 LogMAR; 3 studies, I2 : 0%; p = 0.86); (2) postoperative ECD (-62; -190, 67 cells/mm2 ; 4 studies, I2 : 67%; p = 0.35); (3) rebubbling (risks ratio: 1.04; 0.59, 1.85; 4 studies, I2 : 48%; p = 0.89); and primary graft failure rate (risks ratio: 0.91; 0.32, 2.57; 3 studies, I2 : 0%; p = 0.86). Of all the 5 non-randomized studies, all (100%) were graded as low quality. The overall quality of the analysed studies was low. Randomized controlled trials are needed to confirm no difference or superiority of one approach in terms of CDVA, endothelial cell count and postoperative complication rate between the two arms.

New forceps free injection technique for delivering descemet membrane endothelial keratoplasty preloaded endothelium-in grafts

PURPOSE

To describe a new method for delivering DMEK grafts into the recipient's eye with endothelium inward configuration using a no-forceps injection technique.

METHODS

We retrospectively review 11 patients that underwent DMEK surgery at our institution using a no-forceps injection technique. The graft was preloaded into an intraocular lens (IOL) cartridge and connected to an anterior chamber maintainer (ACM). A 5 ml non luer lock syringe was inserted into the other end of the ACM to create a one-flow system. The cartridge was inserted into the posterior end of an injector, and the graft was successfully delivered into the recipient's eye.

RESULT

Twelve eyes of 11 patients were included. Mean follow-up was 9.16 ± 1.3 months. At baseline, mean best corrected visual acuity (BCVA) was 0.76 ± 0.13 logMAr and mean endothelial cell density (ECD) was 2619.00 ± 115.89 cells/mm2. At follow-up, BCVA significantly improved to 0.22 ± 0.05 logMAR (p = 0.003). Although we observed a significant reduction in ECD at follow-up (1688 ± 182.20, p = 0.002), our patients lost only 35.69 ± 6.36% of endothelial cells.

CONCLUSION

Our technique can help surgeons safely deliver an endothelium-in graft into the recipient's eye. The method doesn't require the use of a forceps, minimizing the risk of endothelial cell loss or graft damage.

Preloaded DMEK With Endothelium Outward: A Multicenter Clinical Study Using DMEK Rapid Device

PURPOSE

The objective of this study is to validate Descemet membrane endothelial keratoplasty (DMEK) Rapid device for preloading DMEK grafts with endothelium outward.

METHODS

In this multicenter retrospective clinical study, DMEK tissues (n = 27) were peeled and preloaded (8.25 mm) in a DMEK Rapid device. The device was loaded in a container prefilled with the storage solution and shipped from a single center in Italy to 4 different centers located in Italy and the United Kingdom. Preloaded tissues were delivered by injecting the graft in the anterior chamber. Patients were monitored at days 1 and 15 and at months 1, 3, and 6, as well as at the last follow-up (9-12 months) postoperatively. Main outcome measures included rebubbling rate and graft failure, corrected distance visual acuity, endothelial cell loss (ECL), and central corneal thickness at all time points. A one-way analysis of variance test comparing day 1 with all later time points was followed with significance at P < 0.05.

RESULTS

The average recorded surgical time was 6 to 25 minutes with no immediate surgical complications. Rebubbling was observed in 7 of 26 cases with one graft failure within 15 days postoperatively. The mean corrected distance visual acuity at day 1 was 0.64 ± 0.49 logMAR, which improved to 0.18 ± 0.43 logMAR at the last follow-up. Endothelial cell density values showed a significant decrease at the last follow-up (1827 ± 565 cells/mm 2 ) ( P < 0.001) compared with the preoperative value (2503 ± 128 cells/mm 2 ), with an average endothelial cell loss of 27%. Central corneal thickness significantly dropped from 694 ± 157 μm at day 1 to 502 ± 42 μm at the last follow-up ( P < 0.001).

CONCLUSIONS

DMEK Rapid device is quick, easy, and efficient for preloading and shipping DMEK grafts internationally in endothelium-outward orientation.

Incidence and management of early postoperative complications in lamellar corneal transplantation

PURPOSE

To provide a comprehensive review of the incidence, risk factors, and management of early complications after deep anterior lamellar keratoplasty (DALK), Descemet stripping automated keratoplasty (DSAEK), and Descemet membrane endothelial keratoplasty (DMEK).

METHODS

A literature review of complications, that can occur from the time of the transplant up to 1 month after the transplant procedure, was conducted. Case reports and case series were included in the review.

RESULTS

Complications in the earliest postoperative days following anterior and posterior lamellar keratoplasty have shown to affect graft survival. These complications include, but are not limited to, double anterior chamber, sclerokeratitis endothelial graft detachment, acute glaucoma, fluid misdirection syndrome, donor-transmitted and recurrent infection, and Uretts-Zavalia syndrome.

CONCLUSION

It is essential for surgeons and clinicians to not only be aware of these complications but also know how to manage them to minimize their impact on long-term transplant survival and visual outcomes.

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.

Inhibiting miR-195-5p Induces Proliferation of Human Corneal Endothelial Cells

Transparency of the human cornea is responsible for clear vision, which is maintained by a monolayer of non-proliferative human corneal endothelial cells (HCEnCs). Dysfunction of these cells can result in irreversible corneal blindness. It is important to identify key factors that limit the proliferation of HCEnCs and thus attempt to reverse them. Extracellular vesicles contain cargo which includes microRNAs (miRNAs) that can modulate a cellular function. In non small cell lung cancer, expression of miR-195-5p has been shown to inhibit proliferation; therefore, we aimed to investigate the inhibitory effect of miR-195-5p in inducing the proliferation of HCEnCs. Human corneal endothelial cell line (HCEC-12) and primary HCEnCs were cultured with miR-195-5p scramble, mimic or inhibitor. Corneal tissues from human cadaveric and FECD donors, and from pigs, mice and rabbits, were used for RT-PCR. miR-195-5p showed an abundance value of 11,363.31 a.u. When normalized against HCEnCs from cadaveric donors, FECD tissues showed a significant upregulation of miR-195-5p (p < 0.05) but was significantly downregulated in pig (p < 0.001), mouse (p < 0.01) and rabbit (p < 0.001) CEnCs, which have known proliferative capacity. Proliferation, cell doubling, and wound healing rates were significantly higher when miR-195-5p was inhibited. Inhibiting miR-195-5p showed a significant improvement in viability (HEC staining), decreased cell apoptosis (TdT-dNTP staining) and expression of ZO-1, NA+/K+-ATPase and Ki-67 markers. Expression of miR-195-5p is found in HCEnCs and FECD cells, which restricts the proliferation of these cells. However, inhibiting miR-195-5p can induce the proliferation of HCEnCs, which opens exciting directions for future research in prolonging FECD pathogenesis by increasing the proliferative capacity of HCEnCs using anti-miR therapy in vivo.

The role of eye banking with cell-based therapies

PURPOSE OF REVIEW

Cell-based therapies are an exciting new frontier in managing corneal diseases. The introduction of these novel therapies may provide new alternatives to corneal transplantation and decrease the dependence on donor corneal tissue. These changes have the potential to significantly impact eye banking in the future.

RECENT FINDINGS

The current article reviews current research involving cell-based therapy for treating corneal disorders, including cultivated limbal stem cell transplantation, limbal mesenchymal stem cells for stromal regeneration, and the use of human-cultivated endothelial cells. We will look at barriers to the development and implementation of these therapies.

SUMMARY

As corneal surgery expands to include cell-based therapies; eye banks will need to redefine their role to support the everchanging landscape of corneal surgery and the decreased demand for corneal donor tissue.

Intraoperative OCT for Lamellar Corneal Surgery: A User Guide

Intraoperative OCT is an innovative and promising technology which allows anterior and posterior segment ocular surgeons to obtain a near-histologic cross-sectional and tomographic image of the tissues. Intraoperative OCT has several applications in ocular surgery which are particularly interesting in the context of corneal transplantation. Indeed, iOCT images provide a direct and meticulous visualization of the anatomy, which could guide surgical decisions. In particular, during both big-bubble and manual DALK, the visualization of the relationship between the corneal layers and instruments allows the surgeon to obtain a more desirable depth of the trephination, thus achieving more type 1 bubbles, better regularity of the plane, and a reduced risk of DM perforation. During EK procedures, iOCT supplies information about proper descemetorhexis, graft orientation, and interface quality in order to optimize the postoperative adhesion and reduce the need for re-bubbling. Finally, mushroom PK, a challenging technique for many surgeons, can be aided through the use of iOCT since it guides the correct apposition of the lamellae and their centration. The technology of iOCT is still evolving: a larger field of view could allow for the visualization of all surgical fields, and automated tracking and iOCT autofocusing guarantee the continued centration of the image.

DMEK graft: One size does not fit all

Descemet membrane endothelial keratoplasty (DMEK) is a popular procedure for the treatment of corneal endothelial diseases mainly targeting Fuchs endothelial corneal dystrophy (FECD) and pseudophakic bullous keratopathy (PBK). Although DMEK has multiple advantages, it is challenging in terms of graft preparation and delivery. One of the crucial factors of DMEK graft preparation is determining the size of the graft. Evaluating risks and benefits of transplanting larger or smaller grafts compared with the descemetorhexis performed following a standard DMEK procedure thus becomes important. Advanced techniques like pre-loaded DMEK requires pre-selection of graft diameter without physical examination of the eye making it more challenging. Therefore, recognizing the benefits of graft size and the number of transplanted endothelial cells becomes essential. Smaller DMEK grafts have been preferred and accepted for grafting. Larger diameter grafts have advantages but can be challenging due to higher detachment rates. We thus aim to review the challenges of preparing and delivering DMEK tissues with small or large diameter based on selected descemetorhexis area, discuss the outcomes based on different graft sizes, highlight related complications and suggest which cases may benefit from adopting smaller or larger graft size.

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

The aim of the study was to assess different temperature ranges for the preservation of pre-loaded Descemet Membrane Endothelial Keratoplasty (DMEK) grafts in the DMEK RAPID Mini device.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Advances in eye banking and corneal tissue processing

PURPOSE OF REVIEW

Eye bank processing of donor corneal tissue has helped to revolutionize and popularize newer corneal transplantation surgeries. In particular, Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) have benefited from eye banks preparing donor corneal tissue in advance of the surgery. As a result of these eye banking advances, surgeons have been able to rapidly adopt these new techniques.

RECENT FINDINGS

This article reviews the techniques that are now being utilized to prepare donor tissue for endothelial keratoplasty (EK) with a focus on Ultrathin-DSAEK, prestamped, prestained, preloaded DMEK tissue, and advancements to improve the safety of donor corneal tissue.

SUMMARY

Collaborative efforts between surgeons and eye banks have been at the core of advances that have been made in EK over the past decade. Corneal surgery starts in the eye bank, and it is important for corneal surgeons to understand the process and appreciate the efforts that have been made to provide them with suitable and safe donor corneal tissue.

Alternatives to endokeratoplasty: an attempt towards reducing global demand of human donor corneas

The cornea is an anterior transparent tissue of the eye that enables the transmission of surrounding light to the back of the eye, which is essential for maintaining clear vision. Corneal endothelial diseases can lead to partial or total blindness; hence, surgical replacement of the diseased corneal tissue with a healthy cadaveric donor graft becomes necessary when the endothelium is damaged. Keratoplasties face a huge challenge due to a worldwide shortage in the supply of human donor corneas. Hence, alternative solutions such as cell or tissue engineering-based therapies have been investigated for reducing the global demand of donor corneas. This review aims at highlighting studies that have been successful at replacing partial or total endothelial keratoplasty.

Delivering Endothelial Keratoplasty Grafts: Modern Day Transplant Devices

PURPOSE

To summarize the graft loading, transporting and delivery devices used for endothelial keratoplasty (EK).

METHODS

A literature search of electronic databases was performed.

RESULTS

New techniques and devices have been introduced and implemented to prepare, load, transport and transplant the grafts for EK. The advantages are not only limited to the surgical theatre but also widely spread across the eye banking field. Investigation of advanced materials and designs have been rapidly growing with continuous evolution in the field of eye banking and corneal transplantation. Innovative techniques and modern devices have been evaluated to reduce the endothelial cell loss and increase the precision of the transplant in order to benefit both surgeons and the patients.

CONCLUSIONS

It is extremely important to reduce any potential wastage and optimize the use of every available donor cornea due to the limited availability of healthy cadaveric donor corneas required for transplants. As a result, the use of pre-cut and pre-loaded grafts supplied by the eye banks in calibrated devices have been gaining momentum. Innovation in the field of bioengineering for the development of new devices that facilitate excellent clinical outcomes along with reduction in learning curve has shown promising results.

Factors Affecting the Success Rate of Preloaded Descemet Membrane Endothelial Keratoplasty With Endothelium-Inward Technique: A Multicenter Clinical Study

PURPOSE

To evaluate factors affecting the outcomes of preloaded Descemet membrane endothelial keratoplasty (pl-DMEK) with endothelium-inward.

DESIGN

Retrospective clinical case series and a comparative tissue preparation study.

METHODS

Participants: Fifty-five donor tissues for ex vivo study and 147 eyes of 147 patients indicated with Fuchs endothelial dystrophy or pseudophakic bullous keratopathy with or without cataract.

INTERVENTION

Standardized DMEK peeling was performed with 9.5-mm-diameter trephination followed by second trephination for loading the graft (8.0-9.5 mm diameter). The tissues were manually preloaded with endothelium-inward and preserved for 4 days or shipped for transplantation. Live and dead assay and immunostaining was performed on ex vivo tissues. For the clinical study, the tissues were delivered using bimanual pull-through technique followed by air tamponade at all the centers.

MAIN OUTCOME MEASURES

Tissue characteristics, donor and recipient factors, rebubbling rate, endothelial cell loss (ECL), and corrected distance visual acuity (CDVA) at 3, 6, and 12 months.

RESULTS

At day 4, significant cell loss (P = .04) was observed in pl-DMEK with loss of biomarker expression seen in prestripped and pl-DMEK tissues. Rebubbling was observed in 40.24% cases. Average ECL at 3, 6, and 12 months was 45.87%, 40.98%, and 47.54%, respectively. CDVA improved significantly at 3 months postoperation (0.23 ± 0.37 logMAR) (P < .01) compared to the baseline (0.79 ± 0.61 logMAR). A significant association (P < .05) between graft diameter, preservation time, recipient gender, gender mismatch, and recipient age to rebubbling rate was observed.

CONCLUSION

Graft loading to delivery time of pl-DMEK tissues in endothelium-inward fashion must be limited to 4 days after processing. Rebubbling rate and overall surgical outcomes following preloaded DMEK can be multifactorial and center-specific.

Clinical results after single asymmetrical shark fin for graft orientation in DMEK

PURPOSE

Evaluating the effect of a single peripheral triangular mark to ensure the correct anterior-posterior graft orientation in DMEK.

METHODS

Retrospective study of patients scheduled for DMEK due to Fuchs endothelial dystrophy and divided into 2 study groups: Group -M (n = 184) had no mark of the EDM (Endothelial Descemet membrane) and group + M (n = 193) had a triangular peripheral mark. Follow-up time was 1 year after surgery.

RESULTS

The postoperative graft turning and Re-DMEK rate could be significantly reduced by the use of a peripheral mark (p = 0.002, p = 0.001, respectively). Re-DMEK due to primary graft failure was significantly associated with prior graft turning (p < 0.001). Both groups showed comparable values for visual acuity, central corneal thickness and endothelial cell count after a follow-up of 1 year.

CONCLUSION

Single peripheral triangular marking is a simple and cost-saving addition to EDM preparation to ensure the correct orientation of the graft intraoperatively and could lead to a significant reduction in graft turning and re-DMEK rate in this study.

Comparison of clinical outcomes after precut DMEK with or without dextran-containing medium compared to standard DMEK: a prospective pilot study

PURPOSE

To investigate the clinical outcome and complication rate of precut Descemet membrane endothelial keratoplasty (DMEK) in two different culture conditions, dextran-containing and dextran-free medium, and compare the results with the current standard DMEK procedure.

METHODS

A prospective study of 32 eyes suffering from Fuchs endothelial dystrophy were scheduled for DMEK with a follow-up of one year. The eyes were divided into four subgroups. Group + D (n = 7) received a precut DMEK stored in dextran-containing transport medium, and Group - D (n = 9) received a precut DMEK without dextran-containing medium. The respective fellow eyes received a standard DMEK (S) (preparation directly prior to surgery) stored in dextran-containing medium (S-D + ; n = 7) or without (S-D-; n = 9).

RESULTS

Clinical outcome (visual acuity, endothelial cell count, central corneal thickness) and rebubbling rate were comparable for all four groups. None of the patients had a graft failure.

CONCLUSION

The preliminary data of the pilot study show that precut liquid-bubble DMEK leads to comparable clinical results regardless of dextran-containing or dextran-free organ culture medium and is further comparable to the standard DMEK procedure.

Cost analysis of eye bank versus surgeon prepared endothelial grafts

Background

Selective lamellar corneal transplantation (keratoplasty) has overtaken full thickness penetrating keratoplasty as the graft choice for endothelial failure. Even more recently eye bank prepared tissues are becoming increasing popular as a way to reduce the risks of tissue loss and stress during endothelial keratoplasty preparation in the surgical theatre. This study compares costs between surgeon and eye bank prepared tissues for Descemet’s stripping automated endothelial keratoplasty (DSAEK) and Descemet’s membrane endothelial keratoplasty (DMEK).

Methods

Retrospective study conducted at the Royal Liverpool University Hospital including endothelial keratoplasties with a minimum of 6 months follow-up time. Cost analysis included surgical expenses, tissue acquisition fees, cost of patient’s ward admission and out-patient expenses, including cost of re-bubbling procedures, costs of visits, anterior segment imaging and optometrist visits within the first 6 months follow-up.

Results

Ninety-eight eyes of 98 patients were included in the study of which 42 underwent DSAEK surgery and 56 DMEK surgery. Cost analysis of surgical expenses in the DSAEK group showed a significant difference between using surgeon prepared and eye bank prepared tissue (£3866 ± 296 and £4389 ± 360, respectively; p < 0.01) and the same was found in the DMEK group (£3682 ± 167 and £4162 ± 167 for surgeon prepared and eye bank prepared tissues, respectively; p < 0.01). Cost of out-patient visits did not differ significantly in either group.

Conclusions

At the Royal Liverpool University Hospital, eye bank prepared tissues had higher surgical expenses compared to those prepared by the surgeon, while the post-operative care expenses were similar between the two groups.

Corneal Donation: Current Guidelines and Future Direction

PURPOSE

This review aims to outline current practices and guidelines of corneal donation and eye banking, describes the implications of COVID-19 and emerging diseases on the corneal donor pool, and discusses future trends to improve and increase the efficiency of the processes involved in corneal donation and eye banking.

SUMMARY

Corneal screening, preservation, corneal storage, and prevention of systemic disease transmission from donor to recipient have been crucial in shaping the policies of the FDA and eye banks across the world. Eye banks globally have developed varying guidelines and criteria for evaluating the viability of donor corneas. Variables such as the age of the donor, medical history, and potential disease transmission are important screening parameters. While known infectious diseases may be transmissible through the cornea, emerging infectious diseases that are not well studied may be more transmissible than other infections. In particular, coronavirus has impacted corneal transplantation as SARS-CoV-2 expression has been detected in corneal tissue and conjunctiva. In recent years, partial-thickness corneal transplantations have been introduced. Lamellar grafts and other corneal layers are now utilized for transplantation of the specific areas that are damaged.

Approaches for corneal endothelium regenerative medicine

The state of the art therapy for treating corneal endothelial disease is transplantation. Advances in the reproducibility and accessibility of surgical techniques are increasing the number of corneal transplants, thereby causing a global deficit of donor corneas and leaving 12.7 million patients with addressable visual impairment. Approaches to regenerate the corneal endothelium offer a solution to the current tissue scarcity and a treatment to those in need. Methods for generating corneal endothelial cells into numbers that could address the current tissue shortage and the possible strategies used to deliver them have now become a therapeutic reality with clinical trials taking place in Japan, Singapore and Mexico. Nevertheless, there is still a long way before such therapies are approved by regulatory bodies and become clinical practice. Moreover, acellular corneal endothelial graft equivalents and certain drugs could provide a treatment option for specific disease conditions without the need of donor tissue or cells. Finally, with the emergence of gene modulation therapies to treat corneal endothelial disease, it would be possible to treat presymptomatic patients or those presenting early symptoms, drastically reducing the need for donor tissue. It is necessary to understand the most recent developments in this rapidly evolving field to know which conditions could be treated with which approach. This article provides an overview of the current and developing regenerative medicine therapies to treat corneal endothelial disease and provides the necessary guidance and understanding towards the treatment of corneal endothelial disease.

The Last 200 Surgeon-Loaded Descemet Membrane Endothelial Keratoplasty Tissue Versus the First 200 Preloaded Descemet Membrane Endothelial Keratoplasty Tissue

PURPOSE

The purpose of this study was to compare the clinical outcomes from using eye bank-prepared, endothelium-out preloaded Descemet membrane endothelial keratoplasty (DMEK) tissue with those obtained with endothelium-out surgeon-loaded DMEK tissue using the same surgical technique at 1 site.

METHODS

This study retrospectively reviewed 400 consecutive cases of DMEK from March 2016 to April 2018. The last 200 cases using surgeon-loaded tissue were compared with the first 200 cases using preloaded tissue. Statistical analysis was performed using the Wilcoxon signed-rank test, binomial logistic regression, Kruskal-Wallis 1-way analysis of variance, Student t test, or Pearson χ tests.

RESULTS

Comparing surgeon-loaded versus preloaded DMEK tissue, respectively, no statistical difference was found in the mean 6-month postoperative values for endothelial cell loss (32.9% ± 18.5% vs. 29.9% ± 16.4%, P = 0.31), best corrected visual acuity (20/26 vs. 20/25, P = 0.54), or change in central corneal thickness (-14.4% ± 8.9% vs. -15.6% ± 11.7%, P = 0.43). The mean 1-year endothelial cell loss was also not significantly different (37.6% ± 17.2% vs. 33.2% ± 14.8%, P = 0.07). Overall, the rebubble rate for surgeon-loaded tissue was 17.5% and 12.5% for preloaded tissue, a statistically nonsignificant difference. Operative outcomes for mean tissue scroll tightness (1-4) and tissue unscroll time (minutes) for surgeon-loaded and preloaded tissue were similar between groups (2.4 vs. 2.2, P = 0.12 and 3.5 vs. 3.3 minutes, P = 0.50).

CONCLUSIONS

Tissue that is trephinated, stained, and loaded into an injector by the eye bank and then shipped to the surgeon had no difference in clinical outcomes compared with tissue where the surgeon performs these steps. The safety and speed of using preloaded tissue should be considered by DMEK surgeons.

The Influence of Speed During Stripping in Descemet Membrane Endothelial Keratoplasty Tissue Preparation

PURPOSE

To evaluate whether the speed of stripping a Descemet membrane endothelial keratoplasty graft influences the graft scroll width.

METHODS

Human corneas suitable for research were selected for the study. Pairs of corneas were randomly divided into 2 groups: 1 cornea was stripped with a slow speed (group 1) and the contralateral with a fast speed (group 2). Slow speed was defined as the total time greater than 150 seconds or speed <0.057 mm/s. Fast peeling was defined as less than 75 seconds or speed >0.11 mm/s. The grafts acquired were evaluated by microscopy for the graft scroll width and endothelial cell density change pre- and post-preparation.

RESULTS

Twenty corneas of 10 donors were included in the analysis. The mean donor age was 68.6 ± 7.58 years. The mean total time of the tissue preparation in group 1 was 282.7 ± 28 seconds and in group 2 was 126 ± 50 seconds (P-value = 0.00000047). The mean speed of stripping in group 1 was 0.045 ± 0.006 mm/s and in group 2 was 0.266 ± 0.093 mm/s (P-value = 0.000027). The graft width in group 1 was 6.4 ± 0.92 mm and in group 2 was 2.87 ± 0.32 mm (P-value = 0.00000014). The mean endothelial cell loss in group 1 was 389 ± 149 cells/mm and in group 2 was 186 ± 63.44 cells/mm (P-value = 0.00134).

CONCLUSION

We found a correlation between the speed of stripping, scroll width, and endothelial cell loss. Slow-peeled Descemet membrane endothelial keratoplasty grafts result in a wider scroll width but were associated with a greater reduction in endothelial cell density.

Endothelial Cell Viability after DMEK Graft Preparation

Aim: To evaluate the effect of graft preparation and organ-culture storage on endothelial cell density (ECD) and viability of Descemet membrane endothelial keratoplasty (DMEK) grafts.Materials and methods: DMEK grafts (n = 27) were prepared at Amnitrans EyeBank Rotterdam from 27 corneas (15 donors) that were eligible for transplantation but could not be allocated due to the Covid-19-related cancellation of elective surgeries. Cell viability (by Calcein-AM staining) and ECD of five grafts originally scheduled for transplantation were evaluated on the originally planned surgery day, whereas 22 grafts from paired donor corneas were evaluated either directly post-preparation or after 3-7 days of storage. ECD was analyzed by light microscopy (LM ECD) and Calcein-AM staining (Calcein-ECD).Results: Light microscopy (LM) evaluation of all grafts showed an unremarkable endothelial cell monolayer directly after preparation. However, median Calcein-ECD for the five grafts initially allocated for transplantation was 18% (range 92-73%) lower than median LM ECD. For the paired DMEK grafts, Calcein-ECD determined by Calcein-AM staining on the day of graft preparation and after 3-7 days of graft storage showed a median decrease of 1% and 2%, respectively. Median percentage of central graft area populated by viable cells after preparation and after 3-7 days of graft storage was 88% and 92%, respectively.Conclusion: Cell viability of most of the grafts will not be affected by preparation and storage. Endothelial cell damage may be observed for some grafts within hours after preparation, with insignificant additional ECD changes during 3-7 days of graft storage. Implementing an additional post-preparation step in the eye bank to evaluate cell density before graft release for transplantation may help to reduce postoperative DMEK complications.

Viability of preloaded Descemet membrane endothelial keratoplasty grafts with 96-hour shipment

Objective

To assess feasibility and compare the effects of 96-hour shipment of Descemet membrane endothelial keratoplasty (DMEK) grafts as a scroll or a tri-fold on cell viability.

Methods and analysis

DMEK grafts were prepared at the Rocky Mountain Lions Eye Bank. Twenty pre-stripped DMEK grafts, paired from 10 donors, were either tri-folded in an endothelium-in configuration using microforceps and loaded into a plastic Treyetech cartridge, or suctioned in a scrolled endothelium-out configuration into a modified Jones Tube. Grafts were shipped via FedEx to a secondary location and back for 48 hours each way, resulting in a total shipping time of 96 hours. After shipping, grafts were removed from inserters onto glass slides and unfolded using viscoelastic with endothelium facing upwards. Calcein-AM stained grafts were imaged with a fluorescent microscope and endothelial cell loss (ECL) was measured using trainable segmentation in Fiji by a masked grader.

Results

A total of 20 grafts were shipped for 96 hours, split between preloaded tri-folded (n=10) and preloaded scrolled (n=10) tissues. No significant difference in ECL was observed across groups after prolonged shipping (14.8% vs 13.7% ECL respectively, p=0.68).

Conclusion

For preloaded DMEK after 96 hours, both scrolled and tri-folded tissue demonstrated clinically acceptable levels of ECL. The data suggest a wider window of time for endothelial cell viability and is promising for the prospect of international shipment of preloaded grafts.

Synthetic media for preservation of corneal tissues deemed for endothelial keratoplasty and endothelial cell culture

PURPOSE

To compare the difference between various endothelial graft preparation methods and endothelial cell culture from tissues that are preserved in serum-based and synthetic medium.

METHODS

In a randomized masked study, the tissues (n = 64) were preserved in Cornea Max (serum-based) and Cornea Syn (synthetic) series for 36 days at their respective preservation conditions. Following organ culture, corneal tissues (n = 48) were used to prepareDescemet stripping automated endothelial keratoplasty (DSAEK), preloaded ultra-thin (UT) -DSAEK, prestripped Descemet membrane endothelial keratoplasty (DMEK), free-floating DMEK, and preloaded DMEK with endothelium inward and outward grafts. These tissues were preserved for another 4days at room temperature in dextran supplemented media following which they were subjected to trypan blue, alizarin red, live/dead and Zonula Occludens-1 (ZO-1) staining. A separate set of tissues (n = 16) from both the series was used for human corneal endothelial cell (HCEnC) culture. At confluence, the proliferation and cell doubling rate was calculated and the cultured cells were subjected to live/dead, ZO-1, 2A12 and Ki-67 staining. Mann-Whitney test was performed with p < 0.05 deemed statistically significant.

RESULTS

After preparation and preservation of the tissues for endothelial keratoplasty, alizarin red showed standard endothelial morphology from both the groups. Endothelial cell loss, hexagonality and uncovered areas did not show statistically significant differences (p > 0.05) between both groups. For HCEnC, cell doubling rate was 4.7 days (p > 0.05). All the antibodies were expressed in both the groups. Hexagonality, polymorphism, cell area, viable/dead cells and Ki-67 positivity were not statistically significant (p > 0.05).

CONCLUSIONS

Complete synthetic organ culture series is safe and advantageous for carrying out advanced endothelial keratoplasty graft preparation procedures and for HCEnC culture as it is free from animal or animal-derived products.

Techniques, Outcomes, and Complications of Preloaded, Trifolded Descemet Membrane Endothelial Keratoplasty Using the DMEK EndoGlide

PURPOSE

To describe 2 insertion techniques, outcomes, and complications of preloaded, trifolded Descemet membrane endothelial keratoplasty (DMEK) cases using the DMEK EndoGlide inserter.

METHODS

This retrospective, consecutive case series analyzed the first 35 cases using the DMEK EndoGlide performed between October 2018 and October 2019 at a single center. Preloaded, trifolded DMEK tissues were delivered through a fluid-injected or pull-through technique. To inject the tissue, a burst of fluid was delivered into the lumen of the injector with a second instrument. Postoperatively, best-spectacle corrected visual acuity (BSCVA), pachymetry, graft survival, and complications were assessed.

RESULTS

Thirty-five eyes of 29 patients underwent DMEK alone (n = 11), with cataract surgery (n = 21), or with additional surgeries (n = 3). Of these, 19 (54.3%) grafts were injected. Video analysis revealed a median time of 3.5 minutes from graft insertion to opening for gas insertion. Median preoperative BSCVA of 0.398 logMAR improved to 0.097 logMAR (P = 0.02) at 9 months. Median pachymetry decreased from 619 μm to 551 μm (P = 0.03) at 9 months. Median donor endothelial cell count of 2890.5 cells/mm2 reduced to 2123 cells/mm2 (26.6% endothelial cell loss; P = 0.008) 6 months postoperatively. One (2.9%) graft failed due to inverted marking at the eye bank and subsequent reverse implantation.

CONCLUSIONS

Pre-loaded, tri-folded tissues can be implanted with acceptable levels of endothelial cell loss. We describe a no-touch method of injecting pre-loaded, tri-folded tissue and highlight incorrect marking as a potential complication. This may not be identifiable intraoperatively due to lack of scroll formation.

Ultra-thin DSAEK using an innovative artificial anterior chamber pressuriser: a proof-of-concept study

PURPOSE

To report the impact of establishing and maintaining a high intracameral pressure (ICP) of 200 mmHg on UT-DSAEK graft preparation using an artificial anterior chamber pressuriser (ACP) control unit (Moria SA, Antony, France).

METHOD

Retrospective laboratory and clinical study. Four paired donor corneas were mounted on an artificial anterior chamber and subjected to 70 mmHg ("low") and 200 mmHg ("high") ICP using an ACP system. The central corneal thinning rate was measured after 5 min using AS-OCT and the endothelial cell viability was analysed using trypan blue and live/dead staining following 70 mmHg and 200 mmHg ICP. Visual outcomes and complications in a clinical case series of nine patients with bullous keratopathy who underwent UT-DSAEK using 200 mmHg ICP during graft preparation are reported.

RESULTS

Laboratory outcomes showed 2 ± 1% and 2 ± 2% dead cells following 70 mmHg and 200 mmHg ICP respectively. Percentage viability in the 70 mmHg group (52.94 ± 5.88%) was not found to be significantly different (p = 0.7) compared to the 200 mmHg group (59.14 ± 10.43%). The mean corneal thinning rate after applying 200 mmHg ICP was 27 ± 13 μm/min centrally (7.2%/min). In the clinical case series, two cases were combined with cataract surgery. Re-bubbling rate was 11%. At the last follow-up (259 ± 109 days), graft thickness was 83 ± 22 μm centrally, endothelial cell density was 1175 ± 566 cell/mm² and the BCVA of 0.08 ± 0.12 logMAR was recorded with no episodes of rejection.

CONCLUSION

ACP control unit for UT-DSAEK graft preparation helps in consistently obtaining UT-DSAEK grafts without compromising endothelial cell viability.

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.

Eye bank versus surgeon prepared DMEK tissues: influence on adhesion and re-bubbling rate

Aim

To investigate the difference in adhesion and rebubbling rate between eye bank and surgeon prepared Descemet membrane endothelial keratoplasty (DMEK) tissues.

Methods

Laboratory and clinical retrospective comparative interventional case series. Research corneal tissues were obtained for laboratory investigation. The clinical study involved patients with endothelial dysfunction who underwent DMEK surgery and tamponade with air. Tissues were stripped using a standard DMEK stripping technique (SCUBA) and shipped as prestripped or loaded in a 2.2 intra-ocular lens cartridge with endothelium facing inwards (preloaded) before transporting from the eye bank to the surgeon. For surgeon prepared tissues, all the grafts were stripped in the theatre and transplanted or stripped in the laboratory and tested immediately. Adhesion force and elastic modulus were measured in the centre and mid-periphery in a laboratory ex vivo investigation using atomic force microscopy, while rebubbling rates were recorded in the clinical study.

Results

There was no difference in endothelial cell viability between surgeon or eye bank prepared tissue. Surgeon-stripped DMEK grafts in the laboratory investigation showed significantly higher elastic modulus and adhesion force compared to prestripped and preloaded tissues (p<0.0001). In the clinical data, rebubbling rates of 48%, 40% and 15% were observed in preloaded, prestripped and surgeon-stripped DMEK grafts, respectively. Rebubbling rates were significantly associated with combined cataract surgery (p=0.009) and with time from harvesting the graft to the surgery (p=0.02).

Conclusions

Decreased adhesion forces and elastic modulus in eye bank prepared tissues may contribute to increased rebubbling rates.

Clinical outcomes of pre-loaded ultra-thin DSAEK and pre-loaded DMEK

Objective

To compare clinical outcomes and complications between pre-loaded ultra-thin Descemet stripping automated endothelialkeratoplasty (pl-UT-DSAEK) and pre-loaded Descemet membrane endothelial keratoplasty (pl-DMEK).

Methods and analysis

Comparative study in patients with endothelial dysfunction associated with Fuchs endothelial corneal dystrophy and pseudophakic bullous keratopathy who underwent pl-UT-DSAEK or pl-DMEK transplants. For both groups, the tissues were pre-loaded at the Fondazione Banca degli Occhi del Veneto (Venice, Italy) and shipped to The Royal Liverpool University Hospital (Liverpool, UK). Best corrected visual acuity (BCVA) and re-bubbling rates were the main outcome measures.

Results

56 eyes of 56 patients were included. 31 received pl-UT-DSAEK and 25 received pl-DMEK. At 12 months, BCVA (LogMAR) was significantly better for pl-DMEK (0.17±0.20 LogMAR) compared with pl-UT-DSAEK (0.37±0.37 LogMAR, p<0.01). The percentage of people that achieved ≥20/30 was significantly higher in the pl-DMEK group. The rate of re-bubbling, however, was significantly higher for pl-DMEK (44.0%) than for Pl-UT-DSAEK (12.9%), p<0.01.

Conclusion

Pl-DMEK offers better BCVA than pl-UT-DSAEK. The higher re-bubbling rate associated with pre-loaded DMEK is of concern.

Preloaded Descemet Membrane Endothelial Keratoplasty Grafts With Endothelium Outward: A Cross-Country Validation Study of the DMEK Rapid Device

PURPOSE

To validate the "Descemet membrane endothelial keratoplasty (DMEK) Rapid" device for the cross-country transportation of preloaded DMEK grafts preserved with endothelium outward.

METHODS

DMEK grafts were stripped and loaded in the DMEK Rapid device with tissue culture medium (TCM) or transport medium (TM) with endothelium outward. The device was mounted in a 40-mL flask and preserved for 4 days on a rocker to simulate transportation (study A, n = 24) or shipped in the TM from Italy to the United Kingdom (study B, n = 9) and evaluated within 72 hours. All the tissues were stained with Alizarin red. Viability of the cells was checked postsimulations and posttransportation and was confirmed using live/dead staining. Expression of tight junction proteins was evaluated.

RESULTS

In study A, the endothelial cell loss observed from the TCM group was 20.8% (±5.2) compared with 19.5% (±6.7) from the TM group (P = 0.41) after transport simulation. Alizarin red showed minimal uncovered areas in both groups. There were no statistical differences in viability between the TM (80.83%) and TCM groups (78.83%). In study B, 12.9% (±7.8) endothelial cell loss was observed after transporting the tissues from Italy to the United Kingdom with no significant difference between prestrip and posttransportation (P = 0.05). Alizarin red staining did not show any uncovered area. Live/dead analysis showed 85.16% cell viability after transportation. zonula occludens-1 (ZO-1) was expressed in all tissues.

CONCLUSIONS

The DMEK Rapid device is safe for preloading and shipping DMEK grafts internationally with endothelium outward within 72 hours when preserved in the transport media.

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.

Comparison of preloaded grafts for Descemet membrane endothelial keratoplasty (DMEK) in a novel preloaded transport cartridge compared to conventional precut grafts

To determine the safety and graft quality of eye bank precut and preloaded grafts for Descemet membrane endothelial keratoplasty (DMEK) after storage and shipping in a novel preloaded transport cartridge compared to precut grafts in a conventional viewing chamber. In this laboratory proof-of-concept study, 29 human donor corneas that were unsuitable for transplantation with a mean endothelial cell density of 1948 ± 260 cells/mm2 were prepared using liquid bubble technique for producing precut lamellar grafts. The grafts were either preloaded into novel transport cartridge (n = 16) or transferred into conventional Krolman viewing chamber (control, n = 13). Grafts were stored for 24 or 48 h in dextran-containing medium at room temperature and subjected to a shipping simulation. Endothelial cell loss (ECL) and morphology were determined at different steps. Endothelial cell viability staining was performed with calcein dye. Mean ECL in the preloaded transport cartridge was 0.7% ± 1.2% after 24 h and 3.4% ± 1.2% (p = 0.006) after 48 h storage and injection. In the control group the ECL was mean 1.6% ± 2.7% after 24 h compared to 3.7% ± 0.9% (p = 0.042) after 48 h. The slightly higher endothelial cell loss in the viewing chamber group after 48 h was not statistically significant compared to the preloaded transport cartridge (p = 0.8). Calcein staining was comparably low in all groups and correlated with the low ECL in both groups. DMEK grafts can be preloaded into a novel transport cartridge using a "no touch" technique, stored and shipped for up to 2 days in dextran-containing medium without significant ECL.

Free-Floating DMEK in the Host Anterior Chamber: Surgical Management

PURPOSE

To describe a method to visualize and manage a completely detached Descemet membrane endothelial keratoplasty (DMEK) tissue scroll in the anterior chamber.

METHODS

A 56-year-old male patient with pseudophakic bullous keratopathy, who underwent uncomplicated DMEK surgery, had a complete graft detachment diagnosed at 1-week follow-up. The graft was reattached using a new technique, that is, the free-floating graft was stained in the anterior chamber with trypan blue, immediately followed by air injection to separate the host stroma from the dye. The stained DMEK graft was opened by gentle tapping and attached to the host stroma by air tamponade.

RESULT

This technique allowed sufficient staining of DMEK tissue to further evaluate and correct the graft orientation inside the anterior chamber without compromising the stroma. The DMEK graft was attached 1 week after the reattachment procedure. The cornea cleared confirming the functionality of the endothelial cells.

CONCLUSIONS

The technique described may be useful in the cases of complete detachment of DMEK tissue and poor visualization of the DMEK tissue orientation. Staining with trypan blue under a "protective" air bubble can provide sufficient visualization to ensure the unfolding of DMEK tissue and reduce the risk of host stromal staining.

Comparison of in vitro assays to study the effectiveness of antiparasitics against Acanthamoeba castellani trophozoites and cysts

We aimed to compare LDH release assay, trypan blue and fluorescent stainings, and non-nutrient Escherichia coli plate assay in determining treatment efficacy of antiamoebic agents against Acanthamoeba castellanii trophozoites/cysts, in vitro. 1BU trophozoites/cysts were challenged with 0.02% polyhexamethylene biguanid (PHMB), 0.1% propamidine isethionate (PD), and 0.0065% miltefosine (MF). Efficacies of the drugs were determined by LDH release and trypan blue assays, by Hoechst 33343, calcein-AM, and ethidium homodimer-1 fluorescent dyes, and by a non-nutrient agar E. coli plate assay. All three antiamoebic agents induced a significant LDH release from trophozoites, compared to controls (p < 0.0001). Fluorescent-dye staining in untreated 1BU trophozoites/cysts was negligible, but using antiamoebic agents, there was 59.3%-100% trypan blue, 100% Hoechst 33342, 0%-75.3% calcein-AM, and 100% ethidium homodimer-1 positivity. On E. coli plates, in controls and MF-treated 1BU trophozoites/cysts, new trophozoites appeared within 24 h, encystment occurred after 5 weeks. In PHMB- and PD-treated 1BU throphozoites/cysts, irregularly shaped, smaller trophozoites appeared after 72 h, which failed to form new cysts within 5 weeks. None of the enzymatic- and dye-based viability assays tested here generated survival rates for trophozoites/cysts that were comparable with those yielded with the non-nutrient agar E. coli plate assay, suggesting that the culture-based assay is the best method to study the treatment efficacy of drugs against Acanthamoeba.

Clinical Outcomes Of Descemet Membrane Endothelial Keratoplasty Using The Bonfadini-Todd Injector For Graft Insertion

Purpose

To evaluate the clinical outcomes of using an Alcon intraocular lens (IOL) B cartridge for graft insertion during Descemet membrane endothelial keratoplasty (DMEK).

Patients and methods

We retrospectively reviewed medical charts of patients who underwent DMEK using the Bonfadini-Todd injector, composed of an Alcon IOL B cartridge connected to plastic tubing and a syringe, for graft insertion between May 2016 and August 2018. Patient demographics, diagnoses, donor information, visual acuity, intraocular pressure (IOP), graft position and attachment status, pachymetry, and postoperative complications were recorded.

Results

Twenty-four eyes of 23 patients with an average age of 72.8 ± 10.0 years (range, 48–87 years) were included. Mean follow-up duration was 13.3 ± 6.6 months (range, 3–26 months). Twenty-one (87.5%) patients had a primary diagnosis of Fuchs endothelial dystrophy, two (8.3%) patients had bullous keratopathy and one (4.2%) had Peter’s anomaly. Sixteen (66.7%) cases combined phacoemulsification and IOL implantation. Best-corrected visual acuity improved from a median of 0.398 logMAR preoperatively to 0.097 logMAR (P <0.001) at last follow-up examination, and central corneal thickness decreased from a median of 651 μm to 533.5 μm (P <0.001). Nine of 24 patients (37.5%) required re-bubbling due to partial graft detachment with a mean time of 12.1 ± 9.2 days (range, 5–35 days). One patient (4.2%) developed graft failure after re-bubbling and underwent Descemet stripping endothelial keratoplasty.

Conclusion

The Alcon IOL B cartridge for DMEK graft insertion is safe and simple.

Safety of Long-Term Storage and Shipping of Prestripped, Prestained, and Preloaded Descemet Membrane Endothelial Keratoplasty Tissue

PURPOSE

The purpose of this study was to determine the safety of long-term storage and shipping of prestripped, prestained, and preloaded Descemet membrane endothelial keratoplasty (pDMEK) grafts.

METHODS

A total of 33 cadaveric corneas were prestripped, prestained, and preloaded using modified Jones tube injectors as pDMEK. The corneas were masked to groups that were prepared <9 hours (control), 48 hours, and 72 hours before unloading and analysis. The 48- and 72-hour tissues were shipped by airfreight on each day before arrival to simulate domestic and international shipping. The corneas were then stained using Calcein AM vital dye (Molecular Probes, Eugene, OR) and imaged using an inverted confocal microscope. Primary outcome measures were endothelial cell loss (ECL, %) and sustainability of staining. MetaMorph software (Molecular Devices, Downingtown, PA) was used to quantify ECL, and staining was evaluated subjectively using all-or-none rating.

RESULTS

There was no difference in the mean ECL for the control, 48-hour, and 72-hour groups, which were 25.1% ± 8.8%, 26.4% ± 17.5%, and 19.2% ± 11.5%, respectively (P = 0.45; Kruskal-Wallis test). In all tissues of each group, no loss of staining was identified at each time point of analysis.

CONCLUSIONS

ECL in pDMEK tissue prepared 48 and 72 hours in advance and shipped using standard methods is similar to that in pDMEK tissue prepared on the same day. These findings support the safety of domestic and international shipping of pDMEK grafts.

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.