Graft detachment and rebubbling rate in Descemet membrane endothelial keratoplasty

Effects of graft detachment on the central corneal thickness after uncomplicated Descemet membrane endothelial keratoplasty

PURPOSE

To determine if early central corneal thickness (CCT) and best-corrected visual acuity (BCVA) changes indicate graft detachment after uncomplicated Descemet membrane endothelial keratoplasty (DMEK).

METHODS

In this analysis of our prospectively collected ADDA registry data ( https://drks.de/search/de/trial/DRKS00027180 ), 45 pseudophakic eyes underwent DMEK surgery at the Department of Ophthalmology, RWTH Aachen University. Anterior segment optical coherence tomography (AS-OCT), the presence of stromal ripples on the posterior corneal surface, and BCVA measurements were assessed prior to, 1 day, 1 week, 1 month, and 6 months after surgery.

RESULTS

Eyes were categorized into three groups: no graft detachment (group 1) (20/45; 44.4%), < 1/3 graft detachment (group 2) (14/45; 31.1%), ≥ 1/3 graft detachment followed by rebubbling (group 3) (11/45; 24.4%). Eyes in group 3 had a greater CCT prior to (746.8 ± 95.8 µm vs. 665.0 ± 74.4 µm, P = 0.041), and 1 week (666.8 ± 119.5 µm vs. 556.5 ± 56.8 µm, P = 0.001) after DMEK compared to group 1. By 1 month, CCT in all groups aligned. Comparing prior to and 1 week after DMEK, none of the eyes in group 1 had an increase in CCT, while the CCT increased in 25.0% of eyes in group 2 and 22.2% in group 3. In group 1, 90.0% had a CCT of < 600 µm 1 week after DMEK, compared to only 50.0% in group 2 and 36.4% in group 3. In group 1, 90.0% (18/20) had an improved BCVA 1 week after DMEK, while in groups 2 and 3, 86.7% (12/14) and 18.2% (2/11) improved, respectively. One patient in group 3 showed posterior stromal ripples 1 day and 1 week after DMEK.

CONCLUSION

If 1 week after uncomplicated DMEK CCT is < 600 µm and has decreased from before surgery, BCVA has improved, and there are no posterior stromal ripples, a graft detachment ≥ 1/3 and the need for rebubbling are very unlikely. In all other cases, meticulous slit-lamp and OCT inspection of the peripheral graft for detachments should be advised.

Clinical Outcomes of Descemet Membrane Endothelial Keratoplasty for Iridocorneal Endothelial Syndrome With a Glaucoma Drainage Device

PURPOSE

The purpose of this study was to evaluate the feasibility and clinical outcomes of Descemet membrane endothelial keratoplasty (DMEK) for treating iridocorneal endothelial (ICE) syndrome with a glaucoma drainage device (GDD).

METHODS

In this retrospective, interventional case series, data of ICE eyes with a GDD treated with DMEK were collected at the Zhongshan Ophthalmic Center. A total of 24 patients (24 eyes) with mild-to-moderate ocular anterior segment anomalies together with good intraocular pressure (IOP) control preoperatively were included between March 10, 2014, and November 11, 2021. Cases were performed DMEK with concomitantly procedures, such as goniosynechialysis, an entire recipient's Descemet stripping, trimming of glaucoma tubes, and an inferiorly peripheral iridotomy. Graft survival, corrected distance visual acuity (CDVA), endothelial cell loss, IOP, and surgical complications were documented.

RESULTS

The mean length of follow-up after surgery was 30.8 ± 7.8 months. Postoperative CDVA improved significantly. At 1 and 2 years postoperatively, 10 (50%) of 20 eyes and 7 (47%) of 15 eyes achieved a CDVA of 20/32 or better, cumulative graft success rates by Kaplan-Meier survival analysis were 89% and 67%, and endothelial cell loss were (59 ± 10)% and (71 ± 7)%, respectively. Within the follow-up period, IOP elevation and progressive peripheral anterior synechiae occurred in 7 (29%) and 5 (21%) of 24 eyes, respectively.

CONCLUSIONS

With specific technical modifications, DMEK had not increased the risk of postoperative complications and provided comparable clinical outcomes in the treatment of ICE eyes with a GDD with those observed in the treatment of ICE eyes without a GDD.

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

OBJECTIVE

This study aimed to evaluate the long-term graft survivability of locally prestripped versus imported prestripped Descemet membrane endothelial keratoplasty (DMEK) grafts in Edmonton.

DESIGN

Prospective cohort study of patients who underwent DMEK surgery between January 1, 2020, and December 31, 2020.

PARTICIPANTS

All patients receiving a DMEK transplant during the study period in Edmonton.

METHODS

Two local technicians were trained to prestrip DMEK grafts in Edmonton. When available, local tissue was prestripped for DMEK surgery; otherwise, prestripped DMEK grafts were imported from an accredited American eye bank. Patient characteristics and DMEK graft characteristics and DMEK survivability were evaluated and compared between the 2 groups.

RESULTS

Thirty-two locally prestripped DMEK grafts and 35 imported prestripped DMEK grafts were used during the study period. Donor cornea characteristics and patient characteristics were similar between the 2 groups. Best-corrected visual acuity improved up to 6 months postoperatively and was 0.2 logMAR in the locally prestripped DMEK group and 0.2 logMAR in the imported DMEK group (p = 0.56). Rebubble rates were 25% in the locally prestripped DMEK group and 19% in the imported DMEK group (p = 0.43). There was 1 primary graft failure in each group (p = 0.93). Endothelial cell density decreased by 37% in the locally prestripped DMEK group and by 33% in the imported DMEK group 2 years after transplantation.

CONCLUSIONS

The long-term survivability of locally prepared DMEK grafts is comparable with that of DMEK grafts imported from American eye banks.

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

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

Double-Bubble Technique Assisted by Holding Forceps: A Modified Technique in Descemet Membrane Endothelial Keratoplasty for Vitrectomized Eyes With Scleral Fixated Intraocular Lens

PURPOSE

Several techniques have been developed for graft unfolding approaches in Descemet membrane endothelial keratoplasty (DMEK). However, despite these techniques, graft deployment and configuration in eyes with deep anterior chambers remain challenging in some cases. Therefore, in this study, we described a modified technique for DMEK, known as the "double-bubble technique assisted by holding forceps."

METHODS

This was a retrospective interventional case series. Patients who underwent DMEK between August 2022 and July 2023, including cases with a history of vitrectomy and scleral fixation of intraocular lens, were enrolled in this study. Two experienced surgeons performed DMEK. In brief, after graft insertion into the anterior chamber, the first bubble with a small volume of air was injected above the graft to open the tight roll, and the graft edge was held using a 25-gauge graft manipulator. The second bubble was injected underneath the graft for fixation, while the graft edge was grasped using forceps during gas injection. The graft was released from the forceps. Best spectacle corrected visual acuity, central corneal thickness, endothelial cell density, and incidence of postoperative complications were measured before and after DMEK.

RESULTS

Eleven eyes of 11 patients were included in this study (mean follow-up period, 4.5 ± 4.4 months). Best spectacle corrected visual acuity and central corneal thickness significantly improved postoperatively ( P < 0.001). Rebubbling was required in 2 eyes; no other postoperative complications or primary graft failure were observed.

CONCLUSIONS

The present technique enables safe and feasible DMEK surgery in vitrectomized eyes with scleral fixated IOLs and in those with a deep anterior chamber.

Outcomes and Early Complications Using an Endothelium-in Pull-Through Descemet Membrane Endothelial Keratoplasty Technique With Preloaded Versus Surgeon-Loaded Donor Tissue in Fuchs Patients

PURPOSE

This study aimed to compare outcomes and early complications using an endothelium-in pull-through Descemet membrane endothelial keratoplasty (DMEK) technique with preloaded versus surgeon-loaded donor tissue.

METHODS

Data from 163 eyes of 125 patients at the Wilmer Eye Institute diagnosed with Fuchs endothelial corneal dystrophy who underwent DMEK with or without cataract extraction using surgeon-loaded tissue (n = 83) or preloaded tissue (n = 80) were reviewed. Best-corrected visual acuity and early postoperative complications including small graft detachment (less than one third of the graft area), large graft detachment (more than one third), graft failure, and rebubbling were compared.

RESULTS

Baseline characteristics including age, sex, and visual acuity were not statistically different between the groups. Small graft detachment was observed in 18.1% of the surgeon-loaded and 22.5% of the preloaded group ( P = 0.48), whereas large detachment occurred in 12.0% and 5.0%, respectively ( P = 0.11). Among these, rebubbling was performed in 18 (21.7%) in the surgeon-loaded compared with 12 (15.0%) in the preloaded group ( P = 0.27). The rebubbling rate of the combined procedure (cataract surgery and DMEK) was 21.8% and of DMEK alone was 7.7% ( P = 0.048). Primary graft failure occurred in 2 surgeon-loaded cases (2.4%) and 1 preloaded case (1.3%) ( P = 0.58). There was no difference in postoperative best-corrected visual acuity at 1 year (logarithm of the minimum angle of resolution 0.21 ± 0.25 for the surgeon-loaded vs. 0.16 ± 0.16 for the preloaded group, P = 0.23).

CONCLUSIONS

DMEK surgery using preloaded endothelium-in tissue has comparable outcomes with surgeon-loaded endothelium-in tissue. However, there was a trend toward the lower rebubbling rate in DMEK alone compared with combined procedures.

Re-descemet membrane endothelial keratoplasty (DMEK) with preservation of the original graft after free roll in anterior chamber: A case report

INTRODUCTION

Lamellar keratoplasties have had a great impact in the management of corneal edema due to endothelial dysfunction. Minimally invasive transplant techniques such as Descemet Membrane Endothelial Keratoplasty (DMEK) have helped to reduce the morbidity involved in performing penetrating keratoplasty in this type of patient. Even so, these are complex techniques that are not free of complications and require a long line of surgical learning and an even more demanding experience in postoperative management.

CLINICAL CASE

An 89-year-old woman suffering from Fuchs endothelial dystrophy and undergoing combined cataract and DMEK surgery presented stromal edema predominantly inferior and sectoral detachment of the graft 24 h after the intervention. After re-bubbling in consultations and 4 days later, the graft was observed rolled and free in the anterior chamber. She underwent re-DMEK with preservation of the original graft after 24 h, with de-epithelialization to optimize visualization. The graft was stained with trypan blue and the posterior stroma was protected with air. The graft was reimplanted under intraocular maneuvers and with an air bubble. 24 h after surgery, the adhered graft was observed, with a great decrease in stromal edema. One month later, the patient had a clear cornea, persistent complete graft adhesion, and visual acuity of 0.9.

CONCLUSION

The discovery of free roll in the anterior chamber after DMEK surgery constitutes the most complex form of graft detachment. Corneal edema as well as the arrangement of the different intraocular structures are conditions to be considered for the surgical resolution of this complication. In many cases, surgical repositioning of the graft is feasible, which means saving costs without the need to use new donor corneal tissues.

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.

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.

[Modern techniques and features of selective keratoplasty]

Selective keratoplasty involves replacing the affected layers of the cornea with similar donor tissue. In case of pathological changes in the middle and posterior stroma, deep anterior lamellar keratoplasty (DALK) is performed. Chronic corneal edema caused by endothelial dysfunction is an indication for endothelial keratoplasty - Descemet membrane endothelial keratoplasty (DMEK) or Descemet Stripping Endothelial Keratoplasty (DSAEK). Compared to penetrating keratoplasty (PK), these operations are characterized by a low risk of damage to intraocular structures and a relatively short rehabilitation period. Complications of selective keratoplasty include the formation of a false chamber between the lamellar graft and the recipient's cornea, ocular hypertension during anterior chamber air tamponade. Persistent epithelial defect can be a sign of primary graft failure in DALK, DSAEK and DMEK. Selective keratoplasty is characterized by a lower incidence of immune rejection than PK. In some cases, DALK can be complicated by corneal changes related to suture fixation of the graft. Long-term postoperative use of topical glucocorticoids can cause ocular hypertension and cataracts.

Role of Direct Supervision in the Learning Curve of Descemet Membrane Endothelial Keratoplasty Surgery

PURPOSE

The aim of this study was to compare complication rates of Descemet membrane endothelial keratoplasty (DMEK) performed by directly supervised and nondirectly supervised corneal fellows.

METHODS

This study was a retrospective, comparative case series of DMEK surgeries performed by novice surgeons (less than 15 DMEK cases) with or without direct direct expert supervision. Patients who underwent surgery for Fuchs endothelial dystrophy or pseudophakic bullous keratopathy with a minimum follow-up of 12 weeks were included. Data on patients' demographics, surgical details, surgeon level, intraoperative and postoperative complications, and rate of rebubbling were collected.

RESULTS

In this study, 41 nondirectly supervised and 48 directly supervised DMEK surgeries were included. At 6 months, 67.4% of eyes achieved a best-corrected visual acuity of ≤0.3 logMAR with no significant difference between groups ( P = 0.95). Intraoperative complications occurred in 22% of cases in the nondirect supervision group and 4.2% in the direct supervision group ( P = 0.02). Postoperative complications occurred in 9.8% of cases in the nondirect supervision group and 6.2% of cases in the direct supervision group ( P = 0.7). The rebubbling rate was comparable in the 2 groups (34.1% vs. 33.3%, P = 1.0). Five cases (12.2%), all from the nondirect supervision group, required secondary keratoplasty ( P = 0.02). The overall complication rate was significantly higher in the nondirect supervision group (31.7% vs. 10.4%, P = 0.03).

CONCLUSIONS

Functional success can be achieved in directly supervised or nondirectly supervised DMEK surgery. However, nondirectly supervised DMEK surgery may associate with higher rates of complications.

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.

Descemet membrane endothelial keratoplasty compared with ultrathin Descemet stripping automated endothelial keratoplasty: a meta-analysis

AIMS

This study aims to compare the clinical outcome of Descemet membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) in patients with corneal endothelial dysfunction due to Fuchs' endothelial dystrophy or pseudophakic bullous keratopathy.

METHODS

We conducted a meta-analysis using a literature search of Embase, PubMed, Cochrane CENTRAL, ClinicalTrials.gov and WHO ICTRP databases. We included randomised controlled trials (RCTs) and cohort studies that compared DMEK and UT-DSAEK (graft<130 µm), with a follow-up of ≥12 months, published until 20 February 2022. We used the Revised Cochrane risk-of-bias tool for RCTs and the Risk of Bias in Non-Randomised Studies-of Interventions system for cohort studies.

RESULTS

Out of 144 records, 8 studies (3 RCTs, 2 fellow-eye studies and 3 cohort studies) were included, encompassing 376 eyes, (N=187 DMEK vs N=189 UT-DSAEK). The 12-month logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) was better post-DMEK (mean difference -0.06 (95% CI -0.10 to -0.02)), but with higher rebubbling risk: OR 2.76 (95% CI 1.46 to 5.22). Heterogeneity was significant I2=57%. Findings were consistent when excluding retrospective studies, including only studies with low risk of bias or RCTs only. An analysis of studies with mean DSAEK grafts <70 µm showed no significant difference in BCVA between the procedures. Publication bias was found in the BCVA analysis (Egger's test p=0.023).

CONCLUSIONS

Post-DMEK BCVA is superior to post-UT-DSAEK when using <130 µm grafts. DSAEK grafts <70 µm may not significantly differ from DMEK. The higher risk of rebubbling with DMEK necessitates an appropriate selection of patients.

PROSPERO REGISTRATION NUMBER

CRD42022340805.

Descemet membrane endothelial keratoplasty graft detachments in superior versus temporal approach

PURPOSE

To evaluate the difference in Descemet Membrane Endothelial Keratoplasty (DMEK) graft detachment rate comparing superior versus temporal main incision approach.

METHODS

Retrospective comparative study on patients who underwent DMEK surgery for Fuchs endothelial dystrophy or bullous keratopathy with main wound incision performed at either 90° in the superior approach, or at 180°/0° in the temporal approach. All main incisions were secured with a single 10-0 nylon suture at the end of surgery. Data collected were donor age and gender, endothelial cell counts, graft diameter, recipient age and gender, indication for transplant, surgeon grade, re-bubbling rate, air fill in the anterior chamber (AC) at day one and intra- and early postoperative complications.

RESULTS

187 eyes were included in the study. 99 eyes had DMEK surgery with superior approach, while 88 eyes had temporal approach. The two groups had no differences in donor age and sex, endothelial cell counts, graft diameter, recipient age and sex, indication for transplant, surgeon grade, and air fill in the anterior chamber at day one. Re-bubbling rate was 38.4% for surgeries performed with superior access and 29.5% for those with temporal access(p = 0.186). After exclusion of patients with intraoperative and/or postoperative complication, the difference in re-bubbling rate was higher, although non-significant (37.5% and 25% for superior and temporal approach respectively, p = 0.098).

CONCLUSION

The temporal approach in DMEK showed a trend towards a clinically significant lower rate of post-operative re-bubbling compared to the superior approach, however, no statistically significant difference was noted comparing the two approaches, which both remain feasible options in DMEK surgery.

Video Grading of Descemet Membrane Endothelial Keratoplasty Surgery to Identify Surgeon Risk Factors for Graft Detachment and Rebubbling: A Post Hoc Observational Analysis of the Advanced Visualization In Corneal Surgery Evaluation Trial

PURPOSE

The aim of this study was to explore video-graded intraoperative risk factors for graft detachment (GD) and rebubbling in Descemet membrane endothelial keratoplasty surgery.

METHODS

A post hoc analysis of 65 eyes of 65 pseudophakic subjects with Fuchs endothelial dystrophy that underwent Descemet membrane endothelial keratoplasty surgery as part of the Advanced Visualization In Corneal Surgery Evaluation trial. All surgical recordings were assessed by 2 graders using a structured assessment form. A multinominal regression was performed to estimate the independent effect of video-graded intraoperative factors on the incidence of GD and rebubbling. Secondary outcomes are corrected distance visual acuity and endothelial cell density.

RESULTS

In total, 33 GDs were recorded, of which 17 required rebubbling. No significant predictors for GD or rebubbling were identified. However, the results revealed 2 clinically relevant patterns. An unfavorable graft configuration (ie, wrinkled, tight scroll, or taco-shaped) and a gas-bubble size smaller than the graft diameter were associated with an increased risk of GD [odds ratio (OR) 2.5 and OR 2.26, respectively] and rebubbling (OR 2.0 and OR 2.60, respectively). Inversely, a larger gas-bubble size was associated with a reduced risk of GD (OR 0.37) and rebubbling (OR 0.36). At 3 and 6 months postoperatively, corrected distance visual acuity was poorer in subjects requiring a rebubbling and endothelial cell density loss was higher in subjects with a partial GD.

CONCLUSIONS

Our analysis revealed that the gas-bubble size and graft shape/geometry seem to be relevant clinical factors for GD and rebubbling, whereas descemetorhexis difficulty, degree of graft manipulation, graft overlap, and surgical iridectomy were not associated with an increased risk.

Rebubbling and graft detachment in Descemet membrane endothelial keratoplasty using a standardised protocol

OBJECTIVES

To analyse risk factors and long-term outcomes after rebubbling and graft detachment in Descemet membrane endothelial keratoplasty (DMEK).

METHODS

176 consecutive DMEK grafts of 125 patients performed by 8 surgeons with a standardised technique between January 2015 and July 2022 were analysed. Main outcome measures were graft detachments, rebubbling rate, postoperative outcomes, and risk factors for graft failure and rebubbling.

RESULTS

6 (3.4%) grafts required rebubbling (>1/3 area detached). 40 (22.7%) grafts developed self-resolving partial detachments (<1/3 area detached). The mean time to rebubble was 16 ± 9.4 days. Mean BSCVAs at 5 years postoperative were 0.03 ± 0.16, 0.03 ± 0.14, and 0.15 ± 0.31 logMAR in fully attached, partially detached and rebubbled grafts (P = 0.437). 5-year graft survival were 98%, 90%, and 83% in fully attached, partially detached and rebubbled eyes (P = 0.02). There was significantly greater endothelial cell loss (ECL) in the rebubbled eyes (P = 0.018). Intraoperative trauma was a risk factor for graft failure (HR 1.81; 95% CI: 1.33-2.50; P = 0.023). An indication for surgery other than Fuchs endothelial dystrophy was a risk factor for rebubbling (HR 5.28; 95% CI: 5.11-72.4; P = 0.007).

CONCLUSION

DMEK grafts had better graft survival if there was no partial detachment or rebubbling at 5 years postop. There was significant ECL associated with rebubbling. A standardised technique reduces rebubbling and graft failure risk.

Trial-based cost-effectiveness analysis of Descemet membrane endothelial keratoplasty (DMEK) versus ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK)

PURPOSE

To evaluate the cost-effectiveness of Descemet Membrane Endothelial Keratoplasy (DMEK) versus Ultrathin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK).

METHODS

A cost-effectiveness analysis using data from a multicenter randomized clinical trial was performed. The time horizon was 12 months postoperatively. Patients with Fuchs' endothelial dystrophy were randomized to DMEK (n = 29) or UT-DSAEK (n = 24). Relevant resources from healthcare and societal perspectives were included in the cost analysis. Quality-Adjusted Life Years (QALYs) were determined using the Health Utilities Index Mark 3 (HUI3) and the EuroQol EQ-5D-5L questionnaires. The main outcome was the incremental cost-effectiveness ratio (ICER; incremental societal costs per QALY).

RESULTS

Societal costs averaged €8851 (US$11 406) for DMEK and €8320 (US$10 722) for UT-DSAEK. Higher costs in the DMEK group were mainly caused by higher rebubbling and regraft rates (21% and 7%, vs. 4% and 0% in the UT-DSAEK group). HUI3 QALYs were 0.70 (DMEK) and 0.79 (UT-DSAEK). EQ-5D-5L QALYs were 0.83 (DMEK) and 0.86 (UT-DSAEK). The ICER indicated DMEK was dominated by UT-DSAEK in both analyses. The cost-effectiveness probability for DMEK ranged from 21% to 5% (HUI3 QALYs) and 27%-14% (EQ-5D-5L QALYs), assuming the maximum acceptable ICER ranged from €2500 to €80.000 (US$3222-US$103 093) per QALY.

CONCLUSION

The base case cost-effectiveness analysis favoured UT-DSAEK over DMEK, as costs of DMEK were higher while QALYs were lower. Further studies are required to assess long-term rebubbling and regraft rates and graft survival.

Posterior stromal ripples increase risk of Descemet's membrane endothelial keratoplasty graft detachment worsening over time

PURPOSE

To evaluate anterior segment optical coherence tomography (AS-OCT) features of Descemet's membrane endothelial keratoplasty (DMEK) grafts associated with graft attachment worsening over time.

METHODS

Retrospective case series on patients who received uncomplicated DMEK surgery and for whom subsequent AS-OCT data were available for analysis. Patients' demographics and surgical details were collected. AS-OCT was analysed for graft detachment axial extension, presence of posterior stromal ripples, quadrant involvement (location and number), degree of detachment extension, peripheral roll, presence and amount of air in the anterior chamber (AC). Features associated with re-bubbling and graft detachment worsening over time were identified.

RESULTS

A total of 147 patients with a mean age of 70.8 ± 9.8 years (63% females) were included. AS-OCT was performed at 2.9 ± 2.4 days after surgery. AS-OCT factors associated with re-bubbling were posterior stromal ripples (p = 0.004) and detachment axial extension (p < 0.001). At first follow-up, of the 147 DMEK, 67 showed complete attachment and 80 partial detachment. In those cases of initially completely attached grafts, posterior stromal ripples were associated with the risk of subsequent graft detachment (p = 0.014) together with recipient age (p = 0.043), phaco-combined surgery (p = 0.018) and AS-OCT timing (p = 0.033); while, in the initially partially detached grafts, detachment worsening was associated with posterior stromal ripples (p = 0.025), detachment axial extension (p = 0.003), degrees of detachment involvement (p = 0.029), peripheral roll-in shape (p = 0.033) and presence of air in the AC (p = 0.032). Relative risk (RR) of graft detachment worsening in patients with moderate/severe posterior stromal ripples was 1.75 (95% CI = 1.09-2.81).

CONCLUSION

Posterior stromal ripples and detachment axial extension >1/3 of graft surface area were the main risk factors for detachment worsening over time, and patients showing these features should be monitored closely to identify the need for re-bubbling at an early stage, thus improving surgical outcomes.

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.

Establishing a Biomarker for the Prediction of Short-Term Graft Detachment After Descemet Membrane Endothelial Keratoplasty

PURPOSE

The purpose of this study was to investigate the predictive value of pachymetry mapping 1 day after Descemet membrane endothelial keratoplasty (DMEK) as a biomarker for early graft detachment.

METHODS

This was a post hoc analysis of 65 pseudophakic subjects with Fuchs endothelial dystrophy who underwent DMEK surgery between December 2018 and April 2021 as part of the Advanced Visualization In Corneal Surgery Evaluation international multicenter randomized controlled trial. One eye per patient was included. Preoperatively and 1 day postoperatively, patients underwent anterior segment optical coherence tomography imaging. Using a grid consisting of 25 zones (ie, pachymetry map), corneal thickness and presence of a graft detachment were mapped for each patient. Detachments of any size were considered, regardless of subsequent clinical interventions. Missing data were imputed and subsequently divided into a training and test set. Two prediction methods were evaluated: one model based on absolute corneal thickness and a regression model.

RESULTS

A total of 65 eyes were included for analysis of which 33 developed any form of graft detachment. Preoperatively, no significant differences were observed between the groups ( P = 0.221). Corneal thickness in the corneal zones with a detached graft was significantly increased compared with corneal zones with an attached graft ( P < 0.001). The regression prediction model had an area under the curve of 0.87 (sensitivity: 0.79 and specificity: 0.75), whereas the absolute thickness cutoff model only reached 0.65.

CONCLUSIONS

Pachymetry mapping 1 day after DMEK was predictive for early graft detachment, and the prediction model had a good to excellent performance. This aids in identifying patients at risk for graft detachment and subsequent tailored postoperative care.

Outcomes of the advanced visualization in corneal surgery evaluation trial; a non-inferiority randomized control trial to evaluate the use of intraoperative OCT during Descemet membrane endothelial keratoplasty

Objective

To evaluate if an intraoperative-OCT (iOCT) optimized surgical protocol without prolonged overpressure is non-inferior to a standard protocol during Descemet membrane endothelial keratoplasty (DMEK).

Methods

Sixty-five pseudophakic eyes of 65 patients with Fuchs endothelial dystrophy scheduled for routine DMEK were recruited in this prospective non-inferiority international multicenter randomized control trial. Subjects were randomized to the control arm (n=33) without iOCT-use and raising the intraocular pressure above normal physiological limits for 8 minutes (i.e., overpressure) or the intervention arm (n=32) with OCT-guidance to assess graft orientation and adherence, while refraining from prolonged overpressure. The primary outcome was the incidence of postoperative surgery-related adverse events (AE). The non-inferiority margin was set at a risk difference of 10%. Secondary outcomes included iOCT-aided surgical decision making, surgical times, and endothelial cell density (ECD) corrected distance visual acuity (CDVA) at 6 months follow-up.

Results

In the intervention group, 12 subjects developed 13 AEs compared to 13 AEs in 10 subjects in the control group (P=0.644). The risk difference measured -0.32% (95%CI: -10.29 - 9.84). The ECD and CDVA did not differ between the two groups 3 and 6 months postoperatively (P=>0.05). Surgeons reported that iOCT aided surgical decision-making in 40% of cases. Surgery and graft unfolding time were, respectively, 13% and 27% shorter in the iOCT-group.

Conclusions

iOCT-guided DMEK surgery with refraining from prolonged over-pressuring was non-inferior compared to conventional treatment. Surgery times were reduced considerably and iOCT aided surgical decision-making in 40% of cases. Refraining from prolonged overpressure did not affect postoperative ECD or CDVA.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT03763721 (NCT03763721).

[A new surgical approach to pre-Descemet's endothelial keratoplasty]

PURPOSE

The study aimed to develop new surgical methods of obtaining and preserving pre-Descemet's endothelial keratoplasty (PDEK) graft in order to reduce the loss of donor material.

MATERIAL AND METHODS

The study was conducted on 30 sclerocorneal discs, which were divided into three groups. The first group consisted of 10 sclerocorneal discs to which the standard PDEK graft preparation technique was applied. The second group consisted of 10 sclerocorneal discs, where the PDEK graft preparation was done using the optimized method 1 involving the KD Ring fixator, KD Base for PDEK, KD-30G needle with 5 mL syringe connected to the spring-load plunger, a preservative solution. The third group consisted of 10 sclerocorneal discs with PDEK graft prepared using the optimized method 2, which differed from the optimized method 1 in additional use of the KD artificial chamber for PDEK. When successfully acquiring the type-1 "big bubble", the dissected PDEK graft was preserved for further use in clinical practice using our own technique.

RESULTS

In the first group, formation of the type-1 «big bubble» was achieved only in 5 out of 10 donor corneas (50%). Bubble ruptures happened in 4 cases (40%) and type-2 «big bubble» occurred in 1 case (10%). In the second group (optimized method 1) the type-1 «big bubble» was achieved in 9 cases (90%), while in the third group (optimized method 2) the type-1 «big bubble» was achieved in 10 cases (100%), proving the effectiveness of our PDEK graft preparation technique.

CONCLUSION

We presented a novel surgical approach for acquiring and preserving PDEK graft that minimizes almost all the difficulties that surgeons face, including bubble rupture during pneumodissection and hydrodissection, formation of type-2 and mixed type bubble, and obtaining a PDEK graft of the required size; the details of the surgical technique have been refined. The proposed technique for graft preparation and preservation can be easily implemented in eye banks and is convenient for clinical practice.

The need of rebubbling in case of small graft detachments after Descemet Membrane Endothelial Keratoplasty (DMEK)

Purpose

To investigate the need of rebubbling for small graft detachments after Descemet Membrane Endothelial Keratoplasty (DMEK).

Methods

In this retrospective study we evaluated 111 eyes from 111 patients that showed graft detachment after DMEK surgery and have achieved graft adherence by injection of air or 20% sulfur hexafluoride (SF6) to the anterior chamber (rebubbling group; n = 57) or by spontaneous adherence without intervention (control group; n = 54) at final examination. Subgroups in terms of the maximum height and in terms of the detachment area in relation to graft area were formed. Outcome measures were the increase in best-corrected visual acuity (BCVA) and the decrease in central corneal thickness (CCT) from the measurement before DMEK to six months after surgery and postoperative endothelial cell density.

Results

BCVA increased in the rebubbling group and the control group, the difference being 0.22 logMAR, p = 0.048. For eyes with a maximum height less than 500  µm, the increase of BCVA was 0.39 ± 0,36 logMAR in the control group and 0.62 ± 0,53 logMAR in the rebubbling group, p = 0.045. There was no difference of statistical significance of BCVA between both groups regarding the detachment area of less than 20% in relation to graft area. The mean decrease in CCT and postoperative endothelial cell density showed no significant difference between the rebubbling group and the control group.

Conclusion

Compared to spontaneous graft adherence, a rebubbling shows no beneficial effect on the clinical outcome for small detached DMEK grafts. Rebubbling does not decrease postoperative endothelial cell density.

Clinical Outcomes of Preloaded Descemet Membrane Endothelial Keratoplasty With Endothelium Inward: A 24-Month Comparative Analysis Between Fuchs Endothelial Corneal Dystrophy and Bullous Keratopathy

PURPOSE

The aim of this study was to compare long-term clinical outcomes of preloaded Descemet membrane endothelial keratoplasty (DMEK) between Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK).

METHODS

In this single-center retrospective clinical case series, 71 eyes of 64 patients indicated with FECD (62%) or BK (38%) (with or without cataract) were treated with preloaded DMEK grafts between March 2018 and February 2020. Standard DMEK peeling, followed by manual folding of the tissue with endothelium-inward orientation and storing in a preloaded fashion inside a 2.2-mm intraocular lens cartridge. All tissues were delivered using a bimanual pull-through technique, followed by air tamponade. Graft unfolding time, endothelial cell loss, corrected distance visual acuity, central corneal thickness, rebubbling rate, and intraoperative and postoperative complications at 1, 3, 6, 12, and 24 months were recorded.

RESULTS

The mean intraoperative graft unfolding time in FECD did not differ from the BK group ( P = 0.6061). Cystoid macular edema did not differ in either group ( P = 0.6866). The rebubbling rate was found to be significantly higher in FECD compared with the BK group ( P = 0.0423). Corrected distance visual acuity significantly improved at the first month after surgery ( P = 0.0012), with no differences between FECD and BK at 24 months ( P = 0.2578). Central corneal thickness was stable postoperatively and showed no differences between the groups ( P = 0.3693). Significantly higher endothelial cell counts were observed in the FECD group at 24 months ( P = 0.0002).

CONCLUSIONS

Preloaded DMEK with "endothelium-in" offers acceptable intraoperative time, rebubbling rate, and clinical outcomes in both FECD and BK groups. Patients with FECD show better postoperative clinical outcomes even if the rebubbling rate is relatively high.

Graft Detachment after Descemet Membrane Endothelial Keratoplasty with and without Cataract Surgery

PURPOSE

To evaluate graft detachment after Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic eyes and DMEK combined with cataract surgery (triple DMEK).

DESIGN

Analysis of 3 single-center prospective cohort studies and 1 randomized controlled trial.

PARTICIPANTS

Participants with Fuchs' endothelial corneal dystrophy.

METHODS

A validated neural network for image segmentation quantified graft detachment on anterior segment OCT (AS-OCT) images 3 days after DMEK and at the 2-week postoperative visit. Area and volume of graft detachment were compared between DMEK only and triple DMEK using generalized estimating equation models and adjusting for participant age and the size of the air bubble.

MAIN OUTCOME MEASURES

Area and volume of DMEK graft detachment.

RESULTS

Among 207 participants with 270 eyes included, 75 pseudophakic eyes had DMEK only and 195 eyes had triple DMEK. A total of 147 eyes had less than one third of detachment at day 3. In 139 of these eyes (95%), detachment was still less than one third at the 2-week scan, indicating that postoperative graft detachment at 2 weeks occurred mainly in eyes with early detachment. When superimposing all 3-dimensional maps from 2 weeks after surgery, the central graft was mainly attached and detachment was located at the graft margin. The mean area of graft detachment decreased from 28% in DMEK only and 38% in triple DMEK to 16% in DMEK only and 25% in triple DMEK at the 2-week postoperative visit. At 2 weeks, the mean area of detachment was 1.85-fold higher (95% confidence interval [CI], 1.34-2.56) and the mean volume was 2.41-fold higher (95% CI, 1.51-3.86) in triple DMEK compared with DMEK. A total of 46 eyes received rebubbling procedures, with 7 eyes (9%) in the DMEK group and 39 eyes (20%) in the triple DMEK group (adjusted risk ratio, 3.1; 95% CI, 1.3-7.1), indicating that rebubbling was more common in eyes undergoing triple DMEK.

CONCLUSIONS

Automated segmentation of AS-OCT images allowed precise quantification of graft detachment over time and identified DMEK combined with cataract surgery as a risk factor. Frequency of operative follow-up might be guided by extent of detachment in the first postoperative days after DMEK.

Glasses-Assisted 3D Display System-Guided Descemet Membrane Endothelial Keratoplasty Tissue Preparation

PURPOSE

The aim of this study was to evaluate the feasibility of Descemet membrane endothelial keratoplasty (DMEK) tissue preparation using a glasses-assisted 3-dimensional (3D) display system and to compare it with a conventional surgical microscope.

METHODS

Healthy pairs of human corneas suitable for penetrating keratoplasty surgery were selected for this study. The tissues were randomly divided into 2 groups. Each pair of corneas had 1 cornea (group 1) prepared with NGENUITY (Alcon) with a 5-second staining time with vision blue, and the fellow cornea (group 2) was prepared using a OPMI Lumera 700 surgical microscope (Carl Zeiss Meditec, Jena, Germany) with a 30-second staining time. DMEK graft preparation time, speed of stripping, graft width, and endothelial cell loss were evaluated.

RESULTS

Twenty-eight pairs of corneas were included in this study. The graft preparation time was significantly higher in the 3D group than in the conventional group (498 ± 147 vs. 418 ± 85 seconds, P value = 0.031). The mean speed of stripping was 0.59 ± 0.081 mm/s in group 1 and 0.089 ± 0.005 mm/s in group 2 ( P value = 0.024). The mean endothelial cell density in group 1 and group 2 before tissue preparation was 2162 ± 115.21 and 2153 ± 122.45, respectively ( P value > 0.1). After tissue preparation, the endothelial cell density reduced to 1911 ± 150.72 in group 1 and 1998 ± 90.72 in group 2 ( P value = P value > 0.05). The graft width was 5.05 ± 0.71 mm in group 1 and 4.92 ± 0.23 mm in group 2 ( P value > 0.05).

CONCLUSIONS

DMEK tissue preparation with 3D display system NGENUITY is feasible with a slightly increased preparation time. The improved visualization allows a reduced staining time that could be beneficial for eye banks because it may reduce the toxic effect of staining colorants.

A machine learning approach to explore predictors of graft detachment following posterior lamellar keratoplasty: a nationwide registry study

Machine learning can be used to explore the complex multifactorial patterns underlying postsurgical graft detachment after endothelial corneal transplantation surgery and to evaluate the marginal effect of various practice pattern modulations. We included all posterior lamellar keratoplasty procedures recorded in the Dutch Cornea Transplant Registry from 2015 through 2018 and collected the center-specific practice patterns using a questionnaire. All available data regarding the donor, recipient, surgery, and practice pattern, were coded into 91 factors that might be associated with the occurrence of a graft detachment. In this research, we used three machine learning methods; a regularized logistic regression (lasso), classification tree analysis (CTA), and random forest classification (RFC), to select the most predictive subset of variables for graft detachment. A total of 3647 transplants were included in our analysis and the overall prevalence of graft detachment was 9.9%. In an independent test set the area under the curve for the lasso, CTA, and RFC was 0.70, 0.65, and 0.72, respectively. Identified risk factors included: a Descemet membrane endothelial keratoplasty procedure, prior graft failure, and the use of sulfur hexafluoride gas. Factors with a reduced risk included: performing combined procedures, using pre-cut donor tissue, and a pre-operative laser iridotomy. These results can help surgeons to review their practice patterns and generate hypotheses for empirical research regarding the origins of graft detachments.

Editorial: Imaging in Ophthalmology

Over the last decade, ophthalmology has significantly benefited from advances in vivo non-invasive ophthalmic imaging techniques that play currently a fundamental role in the clinical assessment, diagnosis, management, and monitoring of a wide variety of conditions involving both the anterior and posterior segment [...]

Descemet membrane endothelial keratoplasty: Update on preoperative considerations, surgical techniques, and outcomes

Descemet membrane endothelial keratoplasty (DMEK) is the closest to the physiological replacement of endothelial cells. In the initial years, the technique was surgically challenging. Over the years, with better understanding and modifications in the surgical steps, the technique has evolved as an alternative to more popular procedure Descemet stripping endothelial keratoplasty. The article highlights the various preoperative, intraoperative, and postoperative nuances of DMEK. Additionally, it summarizes the various comparative and noncomparative studies on DMEK outcomes.

Blast Wound Dehiscence During Descemet Membrane Endothelial Keratoplasty Rebubbling in a Previous Penetrating Keratoplasty: A Case Report

PURPOSE

The purpose of this study was to describe a rare complication of Descemet membrane endothelial keratoplasty (DMEK) rebubbling.

METHODS

An 86-year-old woman with bilateral penetrating keratoplasty (PK) performed 20 years previously for Fuchs endothelial dystrophy underwent DMEK surgery for endothelial corneal decompensation in the left eye. Surgery was complicated in the postoperative period by repeated DMEK graft detachments requiring rebubbling.

RESULTS

The third rebubbling procedure caused a traumatic PK wound dehiscence at the graft-host junction with full-thickness opening of approximately 180 degrees. PK wound dehiscence was resutured in the theater, DMEK lenticule was removed from the eye, and the full-thickness graft was repeated.

CONCLUSIONS

DMEK graft rebubbling in patients with previous PK may lead to traumatic wound dehiscence. Avoidance of excessive increases in intraocular pressure during the rebubbling procedure should be encouraged to decrease the risk of this rare complication.

Role of AS-OCT in Managing Corneal Disorders

Optical coherence tomography (OCT) is analogous to ultrasound biometry in the cross sectional imaging of ocular tissues. Development of current devices with deeper penetration and higher resolution has made it popular tool in clinics for visualization of anterior segment structures. In this review, the authors discussed the application of AS-OCT for diagnosis and management of various corneal and ocular surface disorders. Further, recent developments in the application of the device for pediatric corneal disorders and extending the application of OCT angiography for anterior segment are introduced.

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.

Corneal Endothelial Cell Loss in Glaucoma and Glaucoma Surgery and the Utility of Management with Descemet Membrane Endothelial Keratoplasty (DMEK)

The corneal endothelium has a crucial role in maintaining a clear and healthy cornea. Corneal endothelial cell loss occurs naturally with age; however, a diagnosis of glaucoma and surgical intervention for glaucoma can exacerbate a decline in cell number and impairment in morphology. In glaucoma, the mechanisms for this are not well understood and this accelerated cell loss can result in corneal decompensation. Given the high prevalence of glaucoma worldwide, this review aims to explore the abnormalities observed in the corneal endothelium in differing glaucoma phenotypes and glaucoma therapies (medical or surgical including with new generation microinvasive glaucoma surgeries). Descemet membrane endothelial keratoplasty (DMEK) is increasingly being used to manage corneal endothelial failure for glaucoma patients and we aim to review the recent literature evaluating the use of this technique in this clinical scenario.

Secondary Endothelial Keratoplasty-A Narrative Review of the Outcomes of Secondary Corneal Endothelial Allografts

BACKGROUND

We review the literature on the efficacy and safety outcomes of secondary Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Literature search of English-written publications up to September 27, 2020 in PubMed database, using the terms "endothelial keratoplasty" in combination with keywords "secondary" or "repeat." In addition, we manually searched the references of the primary articles.

RESULTS

Twenty-seven studies (n = 651 eyes) were retained and reviewed, including 10 studies on repeat DSEK, 8 studies on repeat DMEK, 6 studies of DMEK following DSEK, and 3 studies of DSEK after failed DMEK. All studies reported significant improvement in visual acuity after secondary endothelial keratoplasty (EK). Twelve studies compared visual outcomes between primary and secondary EK, reporting conflicting findings. Sixteen studies reported endothelial cell loss rates after secondary EK, and only 1 study reported significantly increased endothelial cell loss rates compared with primary EK. Allograft rejection episodes occurred in 1.8% of eyes (range, 0%-50%). Six studies compared complication rates between primary and secondary EK eyes, and only 1 study found a higher median number of complications. However, 2 studies reported higher regraft failure rates compared with primary EK eyes.

CONCLUSIONS

Secondary EK is surgically feasible and renders significant visual improvement after failed primary EK, although it is not clear whether visual outcomes and allograft survival are comparable with primary EK, raising the question of whether secondary EK eyes are "low risk" as primary EK eyes. Further larger, prospective studies are encouraged to obtain additional quality data on secondary corneal endothelial allotransplantation.

Early Complications With Preloaded Descemet Membrane Endothelial Keratoplasty Are Not Dependent on Optisol-GS Washout or Trypan Blue Restaining

PURPOSE

To describe the intraoperative and early postoperative complications using preloaded Descemet membrane endothelial keratoplasty (DMEK) grafts with intraocular injection of the graft in Optisol-GS and omission of trypan blue restaining.

METHODS

This is a retrospective case series of 132 consecutive eyes with Fuchs endothelial dystrophy or endothelial failure who underwent DMEK using preloaded donor tissue prepared as previously described. The graft was not restained with trypan blue by the surgeon, and Optisol-GS was injected with the graft into the eye instead of being rinsed from the injector. Early postoperative complications (0-8 wk) including intraoperative fibrin formation, intraocular inflammation, elevated intraocular pressure, partial graft detachment requiring rebubble, and early graft failure were recorded.

RESULTS

No eyes developed intraoperative fibrin formation or postoperative inflammation (such as toxic anterior segment syndrome) or elevated intraocular pressure. For eyes with Fuchs corneal dystrophy, our rebubble rate was 21% (22/106 eyes). Early graft failure was noted in 2% (3/132 eyes), which is similar to previous reports.

CONCLUSIONS

Our results suggest that injection of Optisol-GS into the anterior chamber during DMEK graft injection does not lead to increases in intraoperative or early postoperative complications. Trypan blue restaining is not necessary for intraoperative visualization. This simplification can reduce graft manipulation and save time and resources for this procedure.

Chord Mu (µ) and Chord Alpha (α) Length Changes in Fuchs Endothelial Corneal Dystrophy before and after Descemet Membrane Endothelial Keratoplasty (DMEK) Surgery

This paper will evaluate chord mu and alpha length in patients with Fuchs endothelial corneal dystrophy (FECD) and its changes following Descemet membrane endothelial keratoplasty (DMEK). Patients with FECD that underwent DMEK surgery were included in this retrospective study. Scheimpflug Tomography was carried out in order to calculate chord mu and chord alpha lengths prior to surgery and at 3 and 12 months postoperative. This study included 27 eyes from 27 patients. Significant changes in chord mu were observed within the first three months (from 0.47 ± 0.32 to 0.29 ± 0.21 mm, p < 0.01) and remained stable 12 months postoperative (0.30 ± 0.21 mm, p > 0.05). However, chord alpha remained stable throughout the 12 months post surgery (from 0.53 ± 0.19 to 0.49 ± 0.14 mm, p > 0.05). In addition to the pupillary center distance from the corneal center (from 0.35 ± 0.25 to 0.34 ± 0.20 mm, p > 0.05) also remain stable. In FECD patients undergoing DMEK surgery, chord mu length decreased, and chord alpha length remained stable after 12 months of follow-up.

Tips, Tricks, and Guides in Descemet Membrane Endothelial Keratoplasty Learning Curve

Lamellar keratoplasty is fast becoming the most popular form of corneal transplantation. The adoption of Descemet membrane endothelial keratoplasty (DMEK) in the management of Fuchs endothelial dystrophy and pseudophakic bullous keratopathy is partly responsible for this shift in the paradigm of management of corneal pathology. The learning curve of DMEK, however, has been proven to be much steeper than previous endothelial keratoplasty procedures. To ease the procedure, experts have proposed multiple innovative techniques from tissue preparation to graft unfolding to aid the more novice surgeon. Here, we collate and share tips and tricks from our collective experiences to support the learning curve and outcomes in DMEK for both the novice and more experienced corneal transplant surgeons.

New Horizons in the Treatment of Corneal Endothelial Dysfunction

The treatment of corneal endothelial dysfunction has experienced a revolutionary change in the past decades with the emergence of endothelial keratoplasty techniques: descemet stripping automated endothelial keratoplasty (DSAEK) and descemet membrane endothelial keratoplasty (DMEK). Recently, new treatments such as cultivated endothelial cell therapy, Rho-kinase inhibitors (ROCK inhibitors), bioengineered grafts, and gene therapy have been described. These techniques represent new lines of treatment for endothelial dysfunction. Their advantages are to help address the shortage of quality endothelial tissue, decrease the complications associated with tissue rejection, and reduce the burden of postoperative care following transplantation. Although further randomized clinical trials are required to validate these findings and prove the long-term efficacy of the treatments, the positive outcomes in preliminary clinical studies are a stepping stone to a promising future. Our aim is to review the latest available alternatives and advancements to endothelial corneal transplant.

Current development of alternative treatments for endothelial decompensation: Cell-based therapy

Current treatment for corneal endothelial dysfunction consists in the replacement of corneal endothelium by keratoplasty. Owing to the scarcity of donor corneas and the increasing number of transplants, alternative treatments such as cell-based therapies are necessary. In this article, we highlight the biological aspects of the cornea and the corneal endothelium, as well as the context that surrounds the need for new alternatives to conventional keratoplasty. We then review some of those experimental treatments in more detail, focusing on the development of the in vitro and preclinical phases of two cell-based therapies: tissue-engineered endothelial keratoplasty (TE-EK) and cell injection. In the case of TE-EK graft construction, we analyse the current progress, considering all the requirements it must meet in order to be functional. Moreover, we discuss the inherent drawbacks of endothelial keratoplasties, which TE-EK grafts should overcome in order to make surgical intervention easier and to improve the outcomes of current endothelial keratoplasties. Finally, we analyse the development of preclinical trials and their limitations in terms of performing an optimal functional evaluation of cell-based therapy, and we conclude by discussing early clinical trials in humans.

Descemet Membrane Endothelial Keratoplasty in Congenital Hereditary Endothelial Dystrophy: Initial Experiences

PURPOSE

To report our early experiences with Descemet membrane endothelial keratoplasty (DMEK) in congenital hereditary endothelial dystrophy (CHED).

METHODS

Retrospective analysis of medical records of eyes with CHED that underwent DMEK between January 1, 2018, and April 30, 2019, and had a minimum of 1-year follow-up.

RESULTS

Three eyes of 2 CHED patients (a 10-year-old girl and a 22-year-old man) were included. Both had decreased vision and hazy corneas from birth and underwent DMEK during the study period. Surgery was performed by a single surgeon and was uneventful in all 3 eyes. Within 1 month of surgery, the corneal edema cleared, and vision improved significantly. The mean decimal visual acuity improved from 0.15 ± 0.08 (baseline) to 0.33 ± 0.19 at 3 months. The mean central corneal thickness improved from 928 ± 2.3 μm (baseline) to 555.3 ± 25.8 μm at 3 months. The final visual outcome was less in 1 eye because of dense amblyopia. In all 3 eyes, a subtle stromal haze persisted even after resolution of edema. One eye had graft rejection 7 months after surgery because of discontinuation of medications, effectively managed by increasing the frequency of topical steroids.

CONCLUSIONS

DMEK may be a viable option in phakic eyes with CHED.

Descemet Membrane Endothelial Keratoplasty versus Descemet Stripping Automated Endothelial Keratoplasty in Complicated Vitrectomized Eyes

PURPOSE

Vitrectomized eyes pose a technical challenge when performing endothelial keratoplasty (EK). The aim of the study was to compare outcomes of Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK) in complex eyes undergoing pars plana vitrectomy (PPV) prior to or during surgery.

METHODS

This retrospective study included consecutive eyes that underwent pars plana infusion-assisted DMEK or pull-through DSAEK which underwent PPV prior to or during the EK at a tertiary center. Included were eyes with at least 1-year follow-up. The main outcome measures were best-corrected visual acuity (BCVA) and serious adverse events.

RESULTS

Fifty-two eyes (n = 52) with a mean follow-up time of 24.6 ± 7.4 months were included. Both groups were similar in terms of baseline characteristics although the DMEK group had a significantly larger proportion of Fuchs' patients (p = .009). There was no significant difference in postoperative logMAR BCVA between groups at each visit (p > .05 for all). There was a significantly higher proportion of overall serious adverse events (50.0% versus 15.4%, p = .02), retinal detachments (19.2% versus 0.0%, p = .05) and cystoid macular edema (23.1% versus 0.0%, p = .02) following DMEK. Graft detachment occurred more often following DMEK (53.9% versus 11.5%, p = .001) with no significant difference in rebubbling rates (23.1% versus 11.5%, p = .27).

CONCLUSIONS

A significant and similar improvement in BCVA was achieved following DMEK and DSAEK in complex vitrectomized eyes. Patients should be advised regarding the higher rates of potential serious complications associated with a pars plana infusion DMEK in this situation.

Biomaterials for corneal endothelial cell culture and tissue engineering

The corneal endothelium is the posterior monolayer of cells that are responsible for maintaining overall transparency of the avascular corneal tissue via pump function. These cells are non-regenerative in vivo and therefore, approximately 40% of corneal transplants undertaken worldwide are a result of damage or dysfunction of endothelial cells. The number of available corneal donor tissues is limited worldwide, hence, cultivation of human corneal endothelial cells (hCECs) in vitro has been attempted in order to produce tissue engineered corneal endothelial grafts. Researchers have attempted to recreate the current gold standard treatment of replacing the endothelial layer with accompanying Descemet's membrane or a small portion of stroma as support with tissue engineering strategies using various substrates of both biologically derived and synthetic origin. Here we review the potential biomaterials that are currently in development to support the transplantation of a cultured monolayer of hCECs.

Long-term Results of a Combined Procedure of Cataract Surgery and Descemet Membrane Endothelial Keratoplasty With Stromal Rim

PURPOSE

To evaluate the long-term results of combining cataract surgery, intraocular lens (IOL) implantation, and Descemet membrane endothelial keratoplasty with peripheral stromal support (DMEK-S).

METHODS

The outcomes of 107 eyes of 37 patients who had undergone a combination of cataract surgery, IOL implantation, and DMEK-S between October 2007 and February 2015 were retrospectively evaluated. The average follow-up duration was 18.2 ± 18.3 months (range, 6-84 months). Changes in uncorrected and corrected distance visual acuity, spherical equivalent, and corneal endothelial cell density were analyzed. Intraoperative and postoperative complications were also recorded.

RESULTS

The mean logMAR uncorrected distance visual acuity improved from 0.92 ± 0.60 preoperatively to 0.33 ± 0.33, 0.28 ± 0.25, 0.24 ± 0.20, and 0.27 ± 0.27 at 6, 12, 24, and 36 months postoperatively (P < 0.001), respectively. The mean logMAR corrected distance visual acuity improved from 0.62 ± 0.65 preoperatively to 0.17 ± 0.29, 0.13 ± 0.21, 0.07 ± 0.16, and 0.11 ± 0.23 at 6, 12, 24, and 36 months postoperatively (P < 0.001), respectively. The mean endothelial cell density decreases were 50.7% ± 21.1%, 50.8% ± 19.8%, 60.7% ± 16.6%, 62.2% ± 11.8%, and 61.8% ± 20.0% at 6, 12, 24, 36, and 48 months after surgery, respectively. Similar trends, although with slightly better visual outcomes, were found in the subgroup of patients without other eye diseases. The mean final deviation from intended spherical equivalent was 0.77 ± 1.19 D, representing a hyperopic shift.

CONCLUSIONS

A combined procedure of cataract surgery, IOL implantation, and DMEK-S is an effective method of treatment in patients with combined corneal disease and cataract, maintaining visual rehabilitation in the long term. Future developments should be performed to minimize the incidence of complications.

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.

Corneal graft failure: an update

Corneal graft surgery is one of the most successful forms of human solid-tissue transplantation, and nowadays, there is a worldwide expansion of the surgical volume of corneal grafts. This surgery is continuously evolving, with new surgical techniques and postoperative treatments that have considerably increased the chance of survival for the grafts. Despite the high rate of success, corneal transplantation is still complicated by a relevant risk of graft failure. This study investigates the causes that lead to the failure of the different corneal graft surgical techniques and provides an updated synthesis on this topic. A comprehensive review of the main pathological pathways that determine the failure of corneal grafts is provided, analysing the main risk factors and disclosing the survival rates of the principal form of corneal grafts. Our results revealed that penetrating keratoplasty has higher failure rates than lamellar keratoplasty, with immunological rejection being the leading cause of graft failure, followed by late endothelial failure (LEF) and ocular surface disorders. Postoperative glaucoma and dehiscence of the surgical wound represent other important causes of failure. Endothelial keratoplasty showed the lowest rates of failure in the mid-term, with LEF, detachment of the graft and primary graft failure representing the most common pathological reasons for failure.

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.