Descemet membrane endothelial keratoplasty for graft failure following penetrating keratoplasty

Descemet Membrane Endothelial Keratoplasty in Eyes with an Artificial Iris

The purpose of this study is to report the outcome of Descemet membrane endothelial keratoplasty (DMEK) in three eyes with a complex anterior segment and an artificial iris. A retrospective chart review of three cases was performed and clinically meaningful patient characteristics, clinical events, and therapeutic interventions were outlined. A literature search was performed and the clinical course of the three cases was discussed in the context of the published literature. DMEK in the presence of an artificial iris did not match the clinical results of DMEK in uncomplicated eyes. All three eyes experienced major complications, such as failure to achieve graft adherence, early graft failure, or an immune reaction. The indication for DMEK in complex anterior segments with an artificial iris should be made with the awareness of multiple possible complications and the potentially poor prognosis of the procedure.

Descemet Membrane Endothelial Keratoplasty for Penetrating Keratoplasty

Background

Descemet membrane endothelial keratoplasty (DMEK) has been utilized more frequently during recent years to treat penetrating keratoplasty (PKP) graft failures. The perioperative evaluation technique of anterior segment optical coherence tomography (AS-OCT) is increasingly significant. Our goal is to discuss DMEK surgical and clinical for subsequent PKP graft failure, along with significant surgical modifications and adjustments in accordance with preoperative assessment utilizing AS-OCT.

Materials and Methods

Patients' records who performed DMEK for PKP failure were retrospectively reviewed. Demographic information, PKP graft size determined by postoperative problems, corneal donor endothelial cell density (ECD), AS-OCT, central pachymetry, visual acuity (VA) evaluated in Snellen units, intraoperative surgical procedure modifications, and postoperative ECD were all included in the data collection.

Results

The observation was conducted with 16 patients with 16 eyes, nine males and seven females. The observation period is 18 months. DMEK was performed at an average age of 63. Preoperative AS-OCT was performed on all patients, and based on cases, surgical plans were created. Before processing DMEK, the mean VA is 0.04, and central pachymetry is 685 m. They improved considerably to 0.3 (P value = 0.001) and 542 m (P value = 0.008) at the most recent follow-up. About 93.75% of the grafts were adhered to after the procedure. Late decompensation caused a 6.25% graft failure rate. Graft detachment rates and cases requiring rebubble rates were respectively 18.75%.

Conclusion

In DMEK for failed PKP, a good case-specific preoperative assessment by AS-OCT is essential. As a result, it relies on developing a surgical strategy that can improve surgical outcomes, lower the risk of complications, and quicken visual recovery.

Descemet Membrane Endothelial Keratoplasty after failed penetrating keratoplasty- case series and review of the literature

BACKGROUND

This study aims to evaluate visual outcome, central corneal thickness, and re-bubbling rate in a cohort with undersized sequential Descemet Membrane Endothelial Keratoplasty (DMEK) due to endothelial graft decompensation following primary penetrating keratoplasty (PK).

METHODS

All patients who received a sequential DMEK (n = 16) or triple DMEK (n = 2) after failed primary PK between November 2020 and June 2022 were retrospectively evaluated. Analyzed parameters were corrected distance visual acuity (CDVA), central corneal thickness (CCT), re-bubbling rate and graft survival.

RESULTS

18 eyes of 18 patients were included. All patients underwent a DMEK with undersized graft after failed PK(s). Mean time between the last PK and DMEK was 102 ± 82 weeks. Mean follow-up time was 8.9 ± 4.6 months. CDVA increased significantly from 1.12 ± 0.60 logMAR preoperatively to 0.64 ± 0.49 logMAR 6 weeks postoperatively (p = 0.013). Mean CCT decreased significantly from 807 ± 224 μm before to 573 ± 151 μm 6 weeks after DMEK (p = 0.003). Re-bubbling was necessary in eight eyes (44.4%) after a median time of 7 days. The 12-month Kaplan Meier survival was 66.7%.

CONCLUSION

In case of endothelial graft decompensation without stromal scars after primary PK, a DMEK can be performed for selected patients who had satisfying CDVA before the endothelial decompensation. Prior to DMEK indication, an AS-OCT should routinely be performed to circularly search for posterior steps at the PK graft margin, as well as shortly after DMEK to exclude a detachment of the endothelial graft. All patients should be informed about a higher re-bubbling rate in comparison to primary DMEK.

Outcomes of Descemet's membrane keratoplasty in graft failure after penetrating keratoplasty

PURPOSE

To analyze the outcomes and identify the risk factors of failure in Descemet's membrane endothelial keratoplasty (DMEK) for graft failure after penetrating keratoplasty (PKP).

METHODS

Medical records and surgical videos of patients who underwent DMEK for graft failure after PKP were reviewed in this retrospective study. Demographic data, the indication for PKP, number of previous PKPs, duration between the last PKP and graft failure, graft diameter at the last PKP, best-corrected visual acuity (logMAR) before and after DMEK, preoperative additional ocular diseases, and intraoperative and postoperative complications were recorded. Descemet's membrane (DM) attachment was examined on the first day and the first month, postoperatively, and at the last follow-up visit. The patients were divided into two groups according to DM attachment at the last visit (group 1, patients with attached DM; group 2, patients with DM detachment).

RESULTS

Twenty eyes of 20 patients were included in this study. At the last follow-up visit, DM was attached in 13 (65%) patients (Group 1) and detached in 7 (35%) cases (Group 2). The BCVA was improved significantly after DMEK in all patients (2.10 ± 0.4, preoperatively; 1.09 ± 0.8, postoperatively; p = 0.005). There were no significant differences between groups, in terms of age, the number and indication for PKP, the time between the last PKP and DMEK, or history of glaucoma. PKP was performed in all patients in group 2.

CONCLUSION

DMEK is a feasible option with fast visual recovery and a low risk of complications in patients with graft failure after PKP. We found no risk factors for the DM graft detachment, so larger studies are needed to analyze intraoperative or donor-related factors as well.

Graft failure rate and complications after Descemet membrane endothelial keratoplasty in eyes with pre-existing glaucoma

PURPOSE

To evaluate the outcome of Descemet Membrane Endothelial Keratoplasty (DMEK) in eyes with pre-existing glaucoma.

DESIGN

In this retrospective, observational case series we included data of 150 consecutive DMEKs in eyes with pre-existing glaucoma of 150 patients after excluding data of the second treated eye of each patient and of re-DMEKs during follow-up. Cumulative incidences of IOP elevation (IOP > 21 mmHg or ≥ 10 mmHg increase in IOP from preoperative value), post-DMEK glaucoma (need of an additional intervention due to worsening of the IOP), graft rejection, and graft failure rate were analyzed using Kaplan-Meier survival analysis. COX regression analysis was used to evaluate independent risk factors.

RESULTS

The 36-month cumulative incidence of IOP elevation was 53.5% [95 CI 43.5-63.5%] and of post-DMEK glaucoma 36.3% [95 CI 26.3-46.3%]. Graft rejection occurred with a 36-month cumulative incidence of 9.2% [CI 95% 2.3-16.1]. None of the analyzed risk factors increased the risk for the development of graft rejection. The 36-month cumulative incidence of graft failure was 16.6% [CI 95% 8.4-24.8]. Independent risk factors for graft failure were the indication for DMEK "status after graft failure" (n = 16) compared to Fuchs' dystrophy (n = 74) (p = 0.045, HR 8.511 [CI 95% 1.054-68.756]) and pre-existing filtrating surgery via glaucoma drainage device (GDD) (n = 10) compared to no surgery/iridectomy (n = 109) (p = 0.014, HR 6.273 [CI 95% 1.456-27.031]).

CONCLUSION

The risks of postoperative complications (IOP elevation, post-DMEK glaucoma, graft rejection, and graft failure) in patients with pre-existing glaucoma are high. In particular, pre-existing filtrating surgery via GDD implantation-but not trabeculectomy-and DMEK after graft failure increase the risk of graft failure.

Descemet membrane endothelial keratoplasty in complex eyes

PURPOSE OF REVIEW

To review the current literature on Descemet membrane endothelial keratoplasty (DMEK) in complex eyes.

RECENT FINDINGS

DMEK surgery has become a standardized procedure in Fuchs endothelial dystrophy and simple bullous keratopathy. But eyes with more complex disease present unique intraoperative and postoperative challenges to the DMEK surgeon. Poor visualization during surgery, complex anterior segment anatomy, altered anterior chamber dynamics, glaucoma shunts, and congenital or iatrogenic missing or altered iris and lens make DMEK surgery extremely difficult to accomplish.

SUMMARY

DMEK is feasible in complex eyes, including advanced bullous keratopathy, eyes with history of glaucoma or vitreoretinal surgery, previous penetrating keratoplasty, uveitis, pediatric, and congenital anterior segment disorders. The tools and methods reported in the literature to accomplish DMEK in complex eyes vary widely with no particular consensus or standardization of techniques. The outcomes noted for some of these conditions demonstrate the difficulty of the surgery and the uncertainty of long-term graft survival in complex eyes. Both surgical standardization and randomized prospective data will better help elucidate DMEK's role in the corneal rehabilitation of complex eyes.

Graft Failure after PKP and DMEK: What is the Best Option?

Corneal transplantation is the most commonly performed human tissue transplantation procedure worldwide. Due to the large number of grafts, corneal graft failure has become one of the most common indications for corneal transplantation for immunological and non-immunological reasons (e.g. recurrence of underlying disease, high intraocular pressure, grafted guttae, transmitted HSV or CMV infection). The relatively recently developed lamellar grafting techniques have introduced certain potential complications that may lead to graft failure and require approaches other than penetrating keratoplasty for re-grafting. On the other hand, these new lamellar techniques also offer new possibilities for salvaging failed penetrating grafts, with potential advantages over successive penetrating keratoplasties, such as lower intraoperative risks, faster visual rehabilitation and reduced risk of immune reaction. Today, the patient with good healing who is satisfied with his graft before endothelial decompensation, with low astigmatism and no stromal scars, represents the optimal condition for DMEK after PKP. This can also be combined with phacoemulsification (so-called triple DMEK). Otherwise, a penetrating re-keratoplasty with a larger graft (typically excimer laser repeat PKP 8.5/8.6 mm) is performed to treat edema, scars and irregular astigmatism simultaneously. The medical history carries weight in this decision! Re-DMEK in case of graft failure after DMEK and DSAEK does not require any modification of the standard technique and leads to good visual acuity results if performed quickly. If there is clear stromal scarring after multiple (external) DMEKs, PKP can also be considered to rectify the situation. Otherwise causeless recurrent graft failures must suggest herpetic or CMV endotheliitis and, after PCR analysis of the aqueous humour aspirate, be treated appropriately with medication.

DMEK after penetrating keratoplasty: cohort with DMEK grafts and descemetorhexis larger than full-thickness graft

PURPOSE

The study aims to evaluate visual outcome, central corneal thickness, and rebubbling rate in a cohort with oversized DMEK grafts after failed penetrating keratoplasty (PK). The unique feature of the study is a descemetorhexis diameter larger than the full-thickness graft, i.e., peripheral to the PK interface.

METHODS

A monocentric, retrospective evaluation of all patients with endothelial graft failure after PK treated with an oversized DMEK graft and descemetorhexis outside of the PK interface (i.e., in host tissue) between January 2015 and July 2019 at the Department of Ophthalmology at the University of Düsseldorf (Germany) was performed.

RESULTS

Eleven eyes of 10 patients were identified. Mean age was 69 years. On average (arithmetic mean ± standard deviation), 1.7 ± 1.0 previous PKs have been performed per eye in this cohort. The mean time between last PK and DMEK was 10.1 ± 7.3 years (range 2 to 23 years). In all cases, the graft diameter exceeded the diameter of the previous PK and descemetorhexis was performed in host tissue, that is, peripheral to the graft-host interface. Rebubbling was performed in 18.2% of the patients (n = 2 eyes) because of central graft detachment. Mean central corneal thickness showed a statistically significant improvement at 5.3 ± 3.5 months after surgery from 688.23 ± 151.01 to 527.75 ± 88 µm (p = 0.002). Visual acuity increased significantly by 5 lines from 1.24 ± 0.5 logMAR (range from 0.5 to 2) to 0.73 ± 0.76 logMAR (range from 0.1 to 2) within 3 months (p = 0.006). Excluding patients without visual potential and transplant failure, visual acuity improved significantly by 8 lines (p < 0.001), and stayed stable until the last follow-up at 15.1 ± 11.4 months (range 6 to 39 months, p < 0.001, n = 8) after surgery.

CONCLUSION

DMEK can be successfully used to treat endothelial cell failure after PK, and can provide good postoperative results with regards to visual acuity. This study shows that stripping of Descemet's membrane (DM) peripheral to the PK interface is surgically feasible. Overlapping, larger DMEK grafts with more endothelial cells can be used without increasing rebubbling rates and may potentially improve long-term graft survival.

Long-term Results of Intraocular Pressure Elevation and Post-DMEK Glaucoma After Descemet Membrane Endothelial Keratoplasty

PURPOSE

Intraocular pressure (IOP) elevation occurs regularly after Descemet membrane endothelial keratoplasty (DMEK). This study evaluated the long-term incidence of IOP elevation and post-DMEK glaucoma after DMEK.

METHODS

A total of 463 consecutive DMEKs in 352 patients performed between September 2011 and September 2014 at the Universitätsmedizin-Charité Berlin were reviewed. Data of the second treated eye of each patient and of re-DMEKs during the follow-up were excluded. The 12- and 36-month incidence of IOP elevation and post-DMEK glaucoma was analyzed using the Kaplan-Meier survival analysis. IOP elevation was defined as IOP ≥22 mm Hg or ≥10 mm Hg from preoperative baseline. COX regression analysis was used to evaluate the risk factors for IOP elevation and the development of a post-DMEK glaucoma.

RESULTS

The 12-month incidence of IOP elevation was 15.9% [95 confidence interval (CI), 12.0%-19.8%] and that of post-DMEK glaucoma was 3.9% (95 CI, 1.7%-6.1%); the 36-month incidence was 18.8% (95 CI, 14.5%-23.1%) and that of post-DMEK glaucoma was 6.6% (95 CI, 3.7%-9.5%). The most frequent cause was steroid-induced IOP elevation with a 12-month incidence of 11.7% (95 CI, 8.2%-15.2%) and a 36-month incidence of 12.9% (95 CI, 9.2%-16.6%), respectively. The incidence of postoperative pupillary block IOP elevation was 7.5% (95 CI, 4.8%-10.2%). A preexisting glaucoma increased the risk of IOP elevation [P < 0.001, hazard ratio (HR) 3.331; 95% CI, 1.919-5.782] and the development of a post-DMEK glaucoma (P < 0.001, HR 6.633; 95% CI, 2.556-17.215). The preoperative diagnosis also influenced the risk of IOP elevation [Fuchs corneal dystrophy (FED) vs. bullous keratopathy; P = 0.012, HR 2.354; 95% CI, 1.203-4.608] and post-DMEK glaucoma (FED vs. graft failure; P = 0.01, HR 4.412; 95% CI, 1.419-13.723, FED vs. bullous keratopathy; P = 0.09, HR 2.679; 95% CI, 0.858-8.358).

CONCLUSIONS

Incidence of IOP elevation is high in the first 12 months after DMEK, especially steroid-induced IOP elevation. Steroid-induced IOP elevation could be treated effectively by tapering down the steroid medication or changing the steroid drug. A preexisting glaucoma and the preoperative diagnosis increase the risk for an IOP elevation and a post-DMEK glaucoma.

Clinical Course of Different Types of Immune Reactions following Keratoplasty

BACKGROUND

Immune-mediated corneal graft rejection (IR) is a leading cause of corneal graft failure. The endothelium, stroma, epithelium, or a combination can be affected. Little is known about the long-term outcomes of different types of IR.

METHODS

We reviewed the medical records of all keratoplasties that had been performed at our eye centre between 2003 and 2016 (n = 3934) for any kind of IR that occurred between the surgery and 2019. All patients with a definite diagnosis of IR and sufficient clinical data were included in the analysis. IRs were grouped according to the affected part of the graft (endothelial, stromal, epithelial, and mixed). We analysed the dynamics of recovery and the clinical outcomes.

RESULTS

We identified a total of 319 patients with IR. Twenty-seven of those were lost to follow-up and were excluded from further analysis. Of the IRs, 89% affected the endothelium. Endothelial IR resulted more frequently in a considerable loss of endothelial cell density than other forms of IR. Stromal IR showed a lower relapse rate and a better visual recovery than other types of IR and resulted less often in a failure of the graft.

CONCLUSIONS

We herein report comprehensive data about the prognosis regarding functional recovery after different types of IR following keratoplasty. Our data underline that timely recognition and correct classification of IR are important because they determine the clinical course and prognosis.

[Descemet membrane endothelial keratoplasty (DMEK) for graft failure after penetrating keratoplasty and in vascularized high-risk eyes]

BACKGROUND

Descemet membrane endothelial keratoplasty (DMEK) is considered the gold standard for the treatment of corneal endothelial dysfunction and generally leads to good postoperative results. Recently, studies have also analyzed the outcome of DMEK in so-called high-risk eyes.

MATERIAL AND METHODS

The relevant literature and own data on DMEK for graft failure after penetrating keratoplasty and in vascularized high-risk eyes are presented and discussed.

RESULTS

A DMEK for the treatment of transplant failure after penetrating keratoplasty can be considered for eyes without stromal scars and without high astigmatism. A retrospective analysis of 52 patients with failed penetrating grafts showed that DMEK leads to a significant increase in visual acuity, albeit to a lesser extent than after primary DMEK. Rejection and transplant failure rates seem to be similar those seen after penetrating re-keratoplasty and are thus higher than after primary DMEK. A DMEK might also be a feasible option for eyes with corneal neovascularization and stromal edema without stromal scars. A retrospective analysis of 24 eyes with at least 2 vascularized corneal quadrants demonstrated that DMEK leads to a significant improvement in visual acuity and regression of corneal neovascularization. The rejection rate in this cohort was 4.2% and is therefore slightly higher than after low-risk DMEK in eyes without corneal neovascularization but still much better compared to penetrating keratoplasty.

CONCLUSION

Indications for DMEK are expanding and it can be a therapeutic option for transplant failure after penetrating keratoplasty with acceptable outcomes. Furthermore, DMEK seems to be a good option for the treatment of endothelial dysfunction in vascularized high-risk eyes without stromal scars.

Non stripping descemet membrane endothelial keratoplasty in difficult cases: A case series

Endothelial keratoplasty (EK) has been increasingly used instead of penetrating keratoplasty (PK) in the management of post PK graft rejection. Both DSAEK and DMEK involve the surgical removal of the diseased host endothelial cell layer and Descemet's membrane (DM) (descemetorhexis) before transplantation, a technically challenging step, especially in post-PK eyes. Understandably, interest arose when non-stripping DMEK (nDMEK) was described in 2013, and recent studies suggested encouraging results without increased early postoperative failures or complications requiring rebubbling. The purpose of our series was to further study the feasibility and safety of nDMEK and to compare the results with traditional DMEK. This is a single center case series of 3 eyes which underwent nDMEK performed by experienced surgeons (C.P, A.M). Two eyes had nDMEK as a secondary procedure following a failed/rejected PK, while the third case underwent nDMEK on a virgin eye. Undiseased donor DM and a regular host endothelium were required to be eligible for nDMEK. The average change in CCT at last follow-up was -21.2% (±13.3). All required intracameral air injection (rebubbling) within the first few days, with a mean of 2.33 rebubblings per eye, the first one occurring at 6.33±2.52 days after surgery. Non-stripping DMEK surgery appears to be a feasible option, and results are satisfactory at mid to long term. However, in our series, the immediate postoperative period was marked by an increased rebubbling rate. While foreseeable particularly in high-risk cases, surgeons considering this technique should expect a higher risk of early rejection.

The Human Tissue-Engineered Cornea (hTEC): Recent Progress

Each day, about 2000 U.S. workers have a job-related eye injury requiring medical treatment. Corneal diseases are the fifth cause of blindness worldwide. Most of these diseases can be cured using one form or another of corneal transplantation, which is the most successful transplantation in humans. In 2012, it was estimated that 12.7 million people were waiting for a corneal transplantation worldwide. Unfortunately, only 1 in 70 patients received a corneal graft that same year. In order to provide alternatives to the shortage of graftable corneas, considerable progress has been achieved in the development of living corneal substitutes produced by tissue engineering and designed to mimic their in vivo counterpart in terms of cell phenotype and tissue architecture. Most of these substitutes use synthetic biomaterials combined with immortalized cells, which makes them dissimilar from the native cornea. However, studies have emerged that describe the production of tridimensional (3D) tissue-engineered corneas using untransformed human corneal epithelial cells grown on a totally natural stroma synthesized by living corneal fibroblasts, that also show appropriate histology and expression of both extracellular matrix (ECM) components and integrins. This review highlights contributions from laboratories working on the production of human tissue-engineered corneas (hTECs) as future substitutes for grafting purposes. It overviews alternative models to the grafting of cadaveric corneas where cell organization is provided by the substrate, and then focuses on their 3D counterparts that are closer to the native human corneal architecture because of their tissue development and cell arrangement properties. These completely biological hTECs are therefore very promising as models that may help understand many aspects of the molecular and cellular mechanistic response of the cornea toward different types of diseases or wounds, as well as assist in the development of novel drugs that might be promising for therapeutic purposes.

Graft detachments in endothelial keratoplasty

Graft detachment is the most common complication of endothelial keratoplasty. With the ongoing advancements in the field of endothelial keratoplasty, our understanding of risk factors of graft detachments and its management has been evolving. Various prevention measures have been described in literature including presoaking the donor graft, anterior chamber tamponade, venting incisions, sutures to prevent dislocation of graft. Management of a detached graft involves secondary interventions such as rebubbling, suturing and regrafts. In this review, we discuss graft detachment in different types of endothelial keratoplasty techniques including Descemet stripping endothelial keratoplasty, Descemet stripping automated endothelial keratoplasty and Descemet's membrane endothelial keratoplasty; with emphasis on incidence, risk factors, preventive measures and their management.

Long-term outcome of descemet membrane endothelial keratoplasty (DMEK) following failed penetrating keratoplasty (PK)

PURPOSE

To assess the long-term outcome of Descemet membrane endothelial keratoplasty (DMEK) following failed penetrating keratoplasty (PK).

METHODS

Retrospective review of 1840 consecutive DMEK surgeries from the prospective Cologne DMEK database performed between 07/2011 and 08/2017 at the Department of Ophthalmology, University of Cologne.

RESULTS

Fifty-two eyes received a DMEK surgery after failed PK. Main indications for initial PK were Fuchs endothelial corneal dystrophy (23.1%), keratoconus and herpetic keratitis (each 15.4%). Best-corrected visual acuity (BCVA) at 3, 6 and 12 months was 0.72 ± 0.39 (n = 33), 0.56 ± 0.36 (n = 32) and 0.38 ± 0.28 (n = 23), respectively. Two- and 3-year BCVA was 0.37 ± 0.21 (n = 21) and 0.32 ± 0.18 (n = 10). Mean improvement in visual outcome in logMAR lines was +4.3 ± 3.4 at 6 months, +5.0 ± 3.6 at 12 months, +6.0 ± 2.3 at 24 months and +5.4 ± 2.7 at 36 months, respectively. 59.6% received at least one rebubbling and 40.4% did not necessitate a rebubbling. Endothelial cell density (ECD)-decrease at 6 months was 36% (n = 17), 37% at 12 months (n = 17), 40% at 2 years (n = 8) and 32% at 3 years (n = 2). 34.6% of transplants needed a regraft.

CONCLUSION

Descemet membrane endothelial keratoplasty (DMEK) is a feasible treatment option after failed PK having a relatively good long-term outcome.

Corneal transplantation after failed grafts: Options and outcomes

Corneal transplantation is the most commonly performed human tissue transplantation procedure worldwide. Because of the large number of transplants, corneal graft failure has become one of the most common indications for corneal transplantation. The relatively recently developed lamellar transplant techniques have brought about specific potential complications leading to graft failure that may require different approaches to repeat transplantation other than penetrating keratoplasty. On the other hand, these new lamellar techniques also provide novel ways of rescuing failed penetrating grafts, with potential advantages over successive penetrating keratoplasties, such as reduced intraoperative risks and faster visual rehabilitation. We summarize the incidence and risk factors of graft failure for penetrating and lamellar (stromal and endothelial) corneal transplants and discuss the various surgical alternatives currently available to rescue such failed grafts, with a focus on the reported outcomes and limitations.

Corneal graft surgery: A monocentric long-term analysis

PURPOSE

To investigate indications, outcomes and changes in clinical patterns of keratoplasty surgery in a Spanish tertiary eye center.

SETTING

Vissum Instituto Oftalmológico, Alicante, Spain.

METHODS

A retrospective review was performed on clinical records of patients that underwent any kind of corneal transplant from 2001 to 2017 in the study center. Inclusion criteria involved the presence of detailed preoperative examination, surgical report and at least 12 months follow-up after the surgery. A statistical analysis was performed on the indications for keratoplasty, survival rates, type of graft failures, and visual outcomes.

RESULTS

A total of 907 keratoplasties procedures were identified. About 432 penetrating keratoplasty (PK), 148 deep anterior lamellar keratoplasty (DALK), and 134 endothelial keratoplasty (EK) met the inclusion criteria. Cumulative survival rate ranged from 94% to 69% in a 1-year period and from 85% to 45% in a 5-years period according to the different graft types. The main cause for failure was immunological rejection for PK, surface diseases for DALK and primary graft failure for EK. Postoperative visual function improved for all the surgical techniques.

CONCLUSION

Corneal transplant is a challenging surgery still complicated by a relevant risk of failure. Our study offers a useful opinion of the current trends on keratoplasty in our country, where the outcomes of the grafts differ considerably in relation to the indications and the different surgical techniques, with lamellar procedures that showed higher rates of success and better visual outcomes than full-thickness grafts.

[Descemet membrane endothelial keratoplasty DMEK - Donor and recipient step by step]

In 2020 Descemet membrane endothelial keratoplasty (DMEK) has become the gold standard in Germany for the treatment of corneal endothelial diseases; however, the widespread use of DMEK was initially limited due to problems with donor preparation and the difficulty of correctly and gently unfolding the endothelial Descemet membrane (EDM) in the anterior chamber. Following the situational donor selection, the safe single-handed donor preparation of the cornea without tearing or even rupturing the EDM, including the indispensable peripheral semicircular orientation marking. Also presented is a step by step atraumatic loading of the glass cartridge, the introduction of the EDM roll into the anterior chamber, and its safe step by step unfolding based on (1) the sequential use of jets of fluid, (2) repeated tapping on the peripheral/central cornea, (3) controlled flattening of the anterior chamber, (4) use of air bubbles of defined size and finally, the fixation of the EDM in correct orientation to the back of the host cornea with a gas bubble. Since every wrong step with DMEK can have far-reaching consequences for patient and surgeon, this step by step pragmatic approach should minimize the incidence of donor tissue damage and failure in patient maneuvers.

Comparison of Manual and Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty for Failed Penetrating Keratoplasty

PURPOSE

To compare outcomes of manual Descemet membrane endothelial keratoplasty (M-DMEK) and femtosecond laser-assisted Descemet membrane endothelial keratoplasty (F-DMEK) in treatment of penetrating keratoplasty (PK) graft failure.

METHODS

Setting: Retrospective, interventional comparative case series. PatientPopulation: Included were all patients with a failed PK graft who underwent either F-DMEK (10 eyes of 10 patients) or M-DMEK (29 eyes of 29 patients) at Toronto Western Hospital and the Kensington Eye Institute between 2014 and 2019, and had 6 months of postoperative follow-up. OutcomeMeasures: Rates of graft detachment, rebubbling, rejection and failure, best spectacle-corrected visual acuity (BSCVA), and endothelial cell (EC) density.

RESULTS

Rate of significant graft detachment (detachment requiring either rebubble or repeat keratoplasty) was 10.0% in F-DMEK and 65.5% in M-DMEK (P = .003). Rebubble rate was 10.0% in F-DMEK and 58.6% in M-DMEK (P = .011). Primary failure rate was 0% in F-DMEK and 27.6% in M-DMEK (P = .086). Rates of rejection and secondary failure did not differ between the groups (P = 1.000 for both). In a multivariable analysis, F-DMEK was found to be the only independent factor significantly associated with reduced postoperative detachment. Postoperative BSCVA at 6 months returned to prefailure levels in both groups, with no significant difference between the groups at any time point. EC loss rates were 43.8% in F-DMEK and 38.0% in M-DMEK at 6 months (P = .453).

CONCLUSIONS

F-DMEK is a safe and effective procedure in failed PK patients, with outcomes comparable to M-DMEK, and with reduced detachment and rebubble rates. A trend towards reduced primary failure should be further studied.

Differential Survival of Penetrating and Lamellar Transplants in Management of Failed Corneal Grafts

Importance

An increasing proportion of corneal transplant procedures are undertaken for replacement of a failed previous graft. The proportion of lamellar transplant procedures has significantly increased. There are limited large-scale reports on regraft procedures that may help guide surgeons and patients in their choice of surgery.

Objective

To examine the corneal transplant replacement survival rates for the 3 main indications and types of regraft surgery.

Design, Setting, and Participants

This national transplant registry study examined surgery and follow-up data on all corneal transplants performed in the United Kingdom from April 1, 1999, through March 31, 2016.

Main Outcomes and Measures

Actuarial regraft 5-year survival rates were compared for the 3 main indications and types of graft: penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty for keratoconus, PK and endothelial keratoplasty (EK) for Fuchs endothelial dystrophy (FED), and pseudophakic bullous keratopathy (PBK).

Results

A total of 9925 regrafts were analyzed during the 17-year study period. Penetrating keratoplasty represented 7261 cases (73.2%) in the cohort. Endothelial keratoplasty increased by 1361.5%, from 12 (2.6%; 95% CI, 1.3%-4.5%) of all 467 regrafts during 2005-2006 to 292 (38.0%; 95% CI, 34.6%-41.6%) of 768 during 2015-2016. The median time to first regraft for all graft types was 28 months (interquartile range, 10-64 months). When examining all graft types performed for all indications, stratification of 5-year survival was found for successive grafts, with a difference in survival of 25 270 (72.5%; 95% CI, 71.7%-73.2%) from the first graft to 4224 (53.4%; 95% CI, 51.4%-55.4%) from the second graft and 1088 (37.3%; 95% CI, 33.4%-41.3%) from the second to third graft. For first regrafts in keratoconus and PBK, survival after lamellar and PK procedures was similar. For FED, there was a higher regraft survival after PK (375 [70.8%]; 95% CI, 64.6%-76.1%) compared with EK (303 [54.7%]; 95% CI, 45.8%-62.8%) (P < .001). For FED and PBK, there was no difference in first regraft survival identified between EK followed by PK vs PK followed by PK or EK followed by EK vs PK followed by EK.

Conclusions and Relevance

In this large registry-based analysis of corneal regraft survival, regraft survival was found to vary with indication for first graft surgery and for FED with type of regraft procedure performed. For FED and PBK, the permutation of graft and subsequent first regraft procedure were not associated with any survival benefit for the first regraft. These reported outcomes may assist decision-making in management of a failed corneal transplant.

Stepwise Combination of Femtosecond Astigmatic Keratotomy With Phacoemulsification and Toric Intraocular Lens Implantation in Treatment of Very High Postkeratoplasty Astigmatism

PURPOSE

To report the outcomes of stepwise combined femtosecond astigmatic keratotomy (FSAK) and phacoemulsification with toric intraocular lens (IOL) implantation in the treatment of very high astigmatism after either penetrating keratoplasty or deep anterior lamellar keratoplasty.

METHODS

This is a retrospective, interventional case series including 8 eyes of 6 patients with very high astigmatism [≥8.00 diopter (D)] after either penetrating keratoplasty or deep anterior lamellar keratoplasty who underwent FSAK, followed by phacoemulsification and toric IOL implantation. Outcome measures were corneal and manifest astigmatism and uncorrected and best spectacle-corrected visual acuity (UCVA, BSCVA).

RESULTS

The average age was 58.9 ± 5.1 years. The average follow-up time was 40.9 ± 43.8 months. Outcome measure changes after both FSAK and toric IOL implantation were: corneal astigmatism improved from 13.56 ± 4.81 D to 4.48 ± 2.83 D (P < 0.001), manifest astigmatism improved from 9.15 ± 3.86 to 1.46 ± 0.88 D (P = 0.011), UCVA improved from 1.69 ± 0.45 LogMAR (Snellen equivalent ∼20/980) to 0.23 ± 0.11 LogMAR (Snellen equivalent ∼20/33, P < 0.001), and BSCVA improved from 1.01 ± 0.71 LogMAR (Snellen equivalent ∼20/200) to 0.19 ± 0.11 LogMAR (Snellen equivalent ∼20/30, P = 0.015). BSCVA and UCVA at the last follow-up were 20/40 or better in all patients. All procedures were uneventful. Two eyes underwent photorefractive keratectomy after FSAK to regularize and further reduce astigmatism before toric IOL implantation. One patient underwent temporary compression suturing because of FSAK overcorrection.

CONCLUSIONS

Combined stepwise use of FSAK and phacoemulsification with toric IOL implantation was an effective and apparently safe approach in patients with very high postkeratoplasty astigmatism. Additional treatment using photorefractive keratectomy may be beneficial in some cases.

Immune reactions after modern lamellar (DALK, DSAEK, DMEK) versus conventional penetrating corneal transplantation

In the past decade, novel lamellar keratoplasty techniques such as Deep Anterior Lamellar Keratoplasty (DALK) for anterior keratoplasty and Descemet stripping automated endothelial keratoplasty (DSAEK)/Descemet membrane endothelial keratoplasty (DMEK) for posterior keratoplasty have been developed. DALK eliminates the possibility of endothelial allograft rejection, which is the main reason for graft failure after penetrating keratoplasty (PK). Compared to PK, the risk of endothelial graft rejection is significantly reduced after DSAEK/DMEK. Thus, with modern lamellar techniques, the clinical problem of endothelial graft rejection seems to be nearly solved in the low-risk situation. However, even with lamellar grafts there are epithelial, subepithelial and stromal immune reactions in DALK and endothelial immune reactions in DSAEK/DMEK, and not all keratoplasties can be performed in a lamellar fashion. Therefore, endothelial graft rejection in PK is still highly relevant, especially in the "high-risk" setting, where the cornea's (lymph)angiogenic and immune privilege is lost due to severe inflammation and pathological neovascularization. For these eyes, currently available treatment options are still unsatisfactory. In this review, we will describe currently used keratoplasty techniques, namely PK, DALK, DSAEK, and DMEK. We will summarize their indications, provide surgical descriptions, and comment on their complications and outcomes. Furthermore, we will give an overview on corneal transplant immunology. A specific focus will be placed on endothelial graft rejection and we will report on its incidence, clinical presentation, and current/future treatment and prevention options. Finally, we will speculate how the field of keratoplasty and prevention of corneal allograft rejection will develop in the future.

Automated segmentation of the corneal endothelium in a large set of 'real-world' specular microscopy images using the U-Net architecture

Monitoring the density of corneal endothelial cells (CEC) is essential in the management of corneal diseases. Its manual calculation is time consuming and prone to errors. U-Net, a neural network for biomedical image segmentation, has shown promising results in the automated segmentation of images of healthy corneas and good quality. The purpose of this study was to assess its performance in “real-world” CEC images (variable quality, different ophthalmologic diseases). The outcome measures were: precision and recall of the extraction of CEC, correctness of CEC density estimation, detection of ungradable images. A classical approach based on grayscale morphology and water shedding was pursued for comparison. There was good agreement between the automated image analysis and the manual annotation from the U-Net. R-square from Pearson’s correlation was 0.96. Recall of CEC averaged 0.34 and precision 0.84. The U-Net correctly predicted the CEC density in a large set of images of healthy and diseased corneas, including images of poor quality. It robustly ignored image regions with poor visibility of CEC. The classical approach, however, did not provide acceptable results. R-square from Pearson’s correlation with the ground truth was as low as 0.35.

Risk Factors for Endothelial Decompensation after Penetrating Keratoplasty and Its Novel Therapeutic Strategies

Purpose

To review the risk factors and pathogenesis of endothelial decompensation after penetrating keratoplasty (PKP) and its novel therapeutic strategies.

Methods

Literature review.

Results

As the major cause of graft failure in PKP, endothelial decompensation of corneal allograft is considered an irreversible decrease in endothelial cell density and endothelial dysfunction. Various risk factors, including donor status and operative and recipient factors, have been found to be associated with this pathological process. Operative factors like graft size and recipient factors such as indications, glaucoma, or glaucoma surgery history are highly associated with the occurrence of endothelial decompensation, while others are still under investigation. Although the mechanism of these risk factors remains unclear, pathogenesis can be summarized as an acute and chronic loss of endothelium, and cell exchange between donor and recipient is at the core of chronic cell loss. Endothelial keratoplasty has been a useful alternative to repeat standard PKP in eyes with failed grafts. Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK) following failed PKP provide more rapid visual recovery and achieve better rates of graft survival than those of a second PKP.

Conclusions

Any direct or indirect damage to the endothelium could cause the loss, morphological changes, and dysfunction of endothelial cells. Graft size, indications, and recipient glaucoma or glaucoma surgery history are risk factors for endothelial decompensation. DSAEK and DMEK are novel therapeutic strategies for failed PKP grafts and have potential superiorities compared with repeat PKP.

Long-term Outcomes of Repeated Corneal Transplantations: A Prospective Dutch Registry Study

PURPOSE

To compare long-term outcomes of repeated corneal transplantations (CT), based on primary indication (Fuchs endothelial dystrophy [FED] vs pseudophakic bullous keratoplasty [PBK]), surgical technique (penetrating keratoplasty [PK] vs endothelial keratoplasty [EK]), and indication for repeated grafting.

METHODS

In this nonrandomized treatment comparison with national registry data (Netherlands Organ Transplantation Registry, NOTR), data on all consecutive repeated CT following primary PK or EK for FED and PBK between 1994 and 2015 were analyzed, with a maximal follow-up of 5 years. Regraft survival was analyzed using Kaplan-Meier survival curves and univariable and multivariable Cox regression analysis. Secondary outcomes best-corrected visual acuity, spherical equivalent, and refractive astigmatism were compared using linear mixed-model analysis.

RESULTS

A total of 332 repeated CT were analyzed. The number of regrafts increased significantly between 2007 and 2015 (P = .001). Overall 5-year regraft survival was 60% and was higher for FED vs PBK (77% vs 45%, HR = 0.40, P = .001), and re-EK vs re-PK (81% vs 55%, HR = 0.51, P = .041). However, multivariable analysis showed no significant difference in survival based on primary indication, surgical technique, and indication for regrafting. Corrected for baseline, secondary outcomes also did not differ between groups.

CONCLUSIONS

We found a significant increase in repeated CT, coinciding with the introduction of EK in the Netherlands. While univariable analysis suggested better overall regraft survival for FED and (re-)EK, multivariable analysis showed no such difference. This may be owing to allocation of favorable cases to undergo (re-)EK. Similarly, secondary outcomes were determined by the primary CT technique.