Endothelial keratoplasty - a review

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.

Development of Thermoplastic Polyurethane Films for the Replacement of Corneal Endothelial Function of Transparency Maintenance

Endothelial keratoplasty is the main surgical procedure for treating corneal endothelial dysfunction (CED), which is limited by the global shortage of donor corneas. Herein, we developed and evaluated the modified thermoplastic polyurethane (M-TPU) films with gelatin-glycidyl methacrylate to replace the corneal endothelial function and maintain corneal transparency. The films displayed comparable light transmission characteristics with normal corneas and clinically favorable mechanical properties for surgical manipulation. After surface modification, the hydrophilicity and biocompatibility of M-TPU films were significantly improved. In the rabbit CED model, the M-TPU implants exhibited firm adhesion to the exposed stromal surface. The rabbit corneal transparency and thickness could be restored completely within 1 week of M-TPU film implantation. There was no significant inflammatory reaction and immune rejection during the follow-up of 1 month. Proteomic analysis suggested that the complement inhibition, the increase of mineral absorption, and the decrease of P53 apoptosis signaling pathway and lysine degradation might be beneficial in maintaining the corneal transparency. Overall, our study demonstrated the potential of M-TPU films as artificial implants for the replacement of corneal endothelial function to restore corneal thickness and transparency.

Iatrogenic Descemet membrane detachment in the donor lenticule during Descemet stripping automated endothelial keratoplasty

A female patient in her 60s presented with an 8-month history of decreased vision in her right eye. She was diagnosed with pseudophakic bullous keratopathy (PBK), and Descemet stripping automated endothelial keratoplasty (DSAEK) surgery was planned. Intraoperative Descemet membrane detachment (DMD) occurred while inserting the lenticule using the Sheets glide technique. The detachment of the Descemet membrane was detected immediately, and air descemetopexy was performed intraoperatively. Postoperatively, the donor lenticule was attached properly to the stromal bed, except for a focal DMD approximately 3 mm in the inferior part of the lenticule. A second descemetopexy was performed 5 days later, resulting in a complete attachment. A DMD in DSAEK lenticule is an extremely rare complication. Early detection and timely intervention with descemetopexy helped achieve a good anatomical and functional outcome.

The role of eye banking with cell-based therapies

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

DMEK outcome after one year - Results from a large multicenter study in Germany

PURPOSE

Descemet membrane endothelial keratoplasty (DMEK) accounts for >50% of all corneal transplants in Germany. So far, no data from such a large multicenter study have been published.

METHODS

This retrospective study included 3200 DMEKs at seven departments performed for Fuchs endothelial corneal dystrophy (FECD) or bullous keratopathy (BK). We evaluated best corrected visual acuity (BCVA, logMAR), endothelial cell density (ECD, cells/mm² ), minimal corneal thickness (CT, μm), rebubbling-, primary transplant failure- and immune reaction-rate. Changes over time were evaluated by linear mixed models for repeated measures and correlation with case number by center by weighted linear regression.

RESULTS

For patients without vision-limiting comorbidities (74% of all analysed eyes, n = 2270), mean BCVA improved from 0.6 ± 0.4 logMAR to 0.2 ± 0.2 logMAR 6 months (p < 0.001, n = 1441) and 0.1 ± 0.2 logMAR 12 months (p = 0.001, n = 1402) postoperatively. BK- had a worse BCVA compared to FECD-patients (0.3 ± 0.5 vs. 0.1 ± 0.2 logMAR [p < 0.001] at 1 year). ECD declined from 2465 ± 259 cells/mm² (n = 2876 preoperatively) to 1587 ± 433 cells/mm² after 12 months (p < 0.001, n = 1237). Mean rebubbling rate was 0.4 ± 0.7/eye. 784 eyes (25%) received at least one rebubbling. More rebubblings correlated with a lower ECD, a worse BCVA, a higher CT, and higher transplant failure and rejection rates (p < 0.001, p = 0.013 for BCVA at 12 months). A single rebubbling did not influence the BCVA (p = 0.785). Graft failure rate was 3% (n = 67), rejection rate 1.5% (n = 48).

CONCLUSION

Descemet membrane endothelial keratoplasty increases visual acuity with low transplant failure- and rejection-rates. FECD has a better outcome than BK. Since a quarter of all patients need a rebubbling, this should be included in the informed consent. Remarkably, one rebubbling has no influence on the outcome.

The effect of anterior segment parameters on surgical success of Descemet membrane endothelial keratoplasty: a prospective study

PURPOSE

To investigate how anterior segment parameters affect the success of Descemet membrane endothelial keratoplasty (DMEK) in patients with endothelial insufficiency without stromal opacities and to identify factors predisposing them to repeat keratoplasty.

METHODS

Our prospective observational study included patients who underwent primary DMEK for Fuchs' endothelial dystrophy and pseudophakic bullous keratopathy between March 2019 and March 2020. After a detailed ophthalmologic examination, corneal topographic analysis, anterior segment optical coherence tomography (AS-OCT) scans, endothelial cell density (ECD) and axial length (AL) measurements were performed. Surgical success was defined as no endothelial dysfunction during follow-up. Changes in the parameters and how preoperative parameters affect surgical success were investigated.

RESULTS

In 43 eyes of 43 patients (mean age: 68.58 ± 8.51 years), mean visual acuity was 1.73 ± 0.74 LogMAR before DMEK and 0.31 ± 0.29 LogMAR in the final visit. Central corneal thickness (CCT, p = 0.026) and mean anterior chamber depth (ACD, p = 0.001) affected surgical success. Preoperative CCT values greater than 770 µm increased the risk of repeat keratoplasty by 8.75-fold, whereas preoperative ACD values less than 2.5 mm increased the risk by 2.92-fold.

CONCLUSION

Preoperative higher CCT and lower ACD values were associated with surgical failure after DMEK. Early surgery may be considered for more successful results.

TRIAL REGISTRATION

This prospective study has been registered on the ClinicalTrials.gov system with the registration number NCT04420429 on 06/06/2020.

Outcomes of Descemet Membrane Endothelial Keratoplasty Using Cornea From Elderly Donors Aged 80 Years and Older: In the Aftermath of Current Donor Shortage

PURPOSE

The purpose of this study was to report the outcomes of Descemet membrane endothelial keratoplasty (DMEK) using corneas from elderly donors aged 80 years and older.

METHODS

Eighty eyes of 78 patients who underwent DMEK-only or DMEK combined with cataract extraction (triple-DMEK) with surgeon-prepared graft between April 2016 and March 2020 were reviewed. Corrected distance visual acuity, endothelial cell density (ECD), and endothelial cell loss after 6 months, 1 year, and 2 years were analyzed.

RESULTS

The mean donor age was 83.6 ± 3.7 years (range: 80-100 years), and the mean donor ECD was 2889 ± 177 cells/mm 2 (range: 2604-3460 cells/mm 2 ). The mean recipient age was 67.2 ± 6.9 years (range: 60-89 years), and the mean follow-up was 21 ± 11 months (range: 6-52 months). The mean corrected distance visual acuity improved from a preoperative value of 1.36 ± 0.67 logarithm of the minimum angle of resolution to 0.22 ± 0.18 at 6 months (n = 75), 0.21 ± 0.2 at 1 year (n = 64), and 0.23 ± 0.3 logarithm of the minimum angle of resolution at 2 years (n = 41), respectively ( P < 0.001). In 72 eyes (96%), the graft remained transparent until the last follow-up visit. The mean postoperative ECD was 2073 ±336 (n = 75), 1951 ± 379 (n = 65), and 1807 ± 431 cells/mm 2 (n = 41) at 6 months, 1 year, and 2 years, respectively. Five eyes (6.7%) had donor detachments of which 4 required rebubbling. Two grafts failed after 1 year, and 2 eyes (2.6%) had graft rejection, of which 1 eye was reverted successfully by medical management.

CONCLUSIONS

Cornea from elderly donors aged 80 years and older with good selection criteria may be considered for DMEK with successful outcomes. For India and other countries with unmet tissue needs, every best single cornea counts.

Treatment of Descemet's membrane detachment after primary Descemet's stripping automated endothelial keratoplasty during surgery using intraoperative optical coherence tomography

Purpose

To present a novel microscope-integrated optical coherence tomography (iOCT)-guided surgical technique wherein Descemet's membrane detachment (DMD), occurring during vitrectomy, was treated intraoperatively in a patient who had previously undergone Descemet's stripping automated endothelial keratoplasty (DSAEK).

Observations

The surgical technique was performed on a 75-year-old man with a history of DSAEK to intraoperatively treat DMD, which occurred during vitrectomy in the left eye. A fine needle mounted on a syringe was inserted into the supra-Descemet's space under iOCT guidance. The location of the needle was easily identified by its high reflection. The interface fluid was safely aspirated under excellent visualization of the needle tip and the interface. Successful aspiration of the interface fluid was confirmed via iOCT imaging at the end of the surgery. The graft has remained well attached to the cornea throughout the one-year postoperative follow-up.

Conclusion and importance

iOCT-guided surgical interventions provide a safe and accurate approach for treating intraoperative complications in eyes with a history of DSAEK.

Advances in eye banking and corneal tissue processing

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Case series of staged lamellar corneal grafting with thin manual Descemet's stripping endothelial keratoplasty, followed by manual deep anterior lamellar keratoplasty, as an alternative to penetrating keratoplasty

The purpose of this report is to present the outcomes of Descemet's stripping endothelial keratoplasty (DSEK), followed by deep anterior lamellar keratoplasty (DALK), as an alternative to penetrating keratoplasty (PKP) for different indications. Patients in this retrospective case series underwent manual DSEK, followed by manual DALK, for tectonic and/or visual reasons. It includes three cases that underwent DSEK followed by DALK as an alternative to PKP for the following conditions: failed PKP and stromal scarring, aphakic bullous keratopathy and herpetic stromal scarring, and herpetic corneal perforation. All cases had successful anatomical repair with visual improvement. Many corneal conditions involving endothelium and stroma have been traditionally managed with PKP. However, in certain settings with high risk of complications, this might not be an appropriate option. Therefore, for these cases, we propose management with DSEK followed by DALK as an alternative approach in a 'closed anterior chamber' fashion, which can reduce the risk of significant, sometimes irreversible, complications.

Exposure of Ophthalmology Residents to Cornea and Keratorefractive Surgeries in the United States

Purpose To describe the cornea and keratorefractive surgeries experience of U.S. ophthalmology residents.

Methods Deidentified case logs of residents graduating in 2018 were collected from ophthalmology residency program directors in the United States. Using Current Procedure Terminology codes, case logs were reviewed in the categories of cornea and keratorefractive surgeries. Accreditation Council for Graduate Medical Education national graduating resident surgical case logs on cornea procedures published from 2010 to 2020 were also analyzed.

Results Case logs were received for 152/488 (31.1%) residents from 36/115 (31.3%) ophthalmology residency programs. The most common procedures logged by residents as primary surgeons were pterygium removal (4.3 ± 4.2) and keratorefractive surgeries (3.6 ± 6.2). Residents logged an average of 2.4 keratoplasties as primary surgeon, performing an average of 1.4 penetrating keratoplasties (PKs) and 0.8 endothelial keratoplasties (EKs). As assistants, the most common procedures logged were keratorefractive surgeries (6.1 ± 4.9), EKs (3.8 ± 3.3), and PKs (3.5 ± 2.3). Medium or large residency class size was associated with higher cornea procedural volumes (odds ratio: 8.9; 95% confidence interval: 1.1–75.6; p < 0.05).

Conclusion The most common cornea surgeries performed by residents include keratoplasty, keratorefractive, and pterygium procedures. Larger program size was associated with greater relative cornea surgery volume. More specific guidelines for logging of procedures could provide a more accurate assessment of resident exposure to critical techniques such as suturing as well as reflect trends in current practice such as the overall increase in EKs.

Donor-Related Risk Factors for Graft Decompensation Following Descemet's Stripping Automated Endothelial Keratoplasty

Aims

To identify donor-related risk factors associated with graft endothelial failure and postoperative endothelial cell density (ECD) reduction after Descemet's stripping automated endothelial keratoplasty (DSAEK).

Methods

This was a single-center retrospective study conducted from July 2006-December 2016. We included 584 consecutive eyes (482 patients) that underwent DSAEK for the treatment of laser iridotomy-related bullous keratopathy (192 eyes), pseudophakic bullous keratopathy (137 eyes), regraft (96 eyes), Fuchs' endothelial corneal dystrophy (FECD; 59 eyes) and others (100 eyes). Twenty-three donor- and recipient-related risk factors potentially associated with graft failure and ECD reduction were assessed using Cox hazard models and linear mixed effect models.

Results

The median age of the patients was 73.5 years (male; 35.6%). After DSAEK, ECD decreased from 2,674 cells/mm2 (95% confidence interval [CI]; 2,646–2,701) to 1,132 (1,076–1,190) at 12 months and 904 (845–963) at 24 months (P &lt; 0.001). Fifty-five eyes (9.4%) had graft endothelial failure without rejection. This failure was associated with donor pseudophakic lens status (hazard ratio [HR]; 2.67, CI; 1.50–4.76, P = 0.001) and preoperative endothelial folds (HR; 2.82, CI; 1.20–6.62, P = 0.02). The incidence of graft endothelial failure in non-FECD patients was significantly higher among those receiving donor grafts with a pseudophakic lens status and preoperative presence of endothelial folds (P &lt; 0.001). Postoperative ECD loss was significantly greater in eyes with these risk factors compared to those without (P = 0.007).

Conclusions

Pseudophakic status and/or presence of preoperative endothelial folds are the significant donor risk factors for endothelial failure in non-FECD patients.

Y-27632 Promotes the Repair Effect of Umbilical Cord Blood-Derived Endothelial Progenitor Cells on Corneal Endothelial Wound Healing

PURPOSE

To investigate the proliferation of umbilical cord blood-derived endothelial progenitor cells (UCB EPCs) and the differentiation efficiency toward corneal endothelial cell (CEC)-like cells induced by rho-associated protein kinase (ROCK) inhibitor Y-27632 and to determine the most effective strategy for repairing corneal endothelium injuries in rabbits.

METHODS

UCB EPCs were cultured in Endothelial Cell Growth Medium-2 (EGM-2) media or conditioned media (CM) from human CECs, with and without the addition of Y-27632. Bromo-deoxyuridine (BrdU) immunocytochemistry and cell counting kit-8 assays were used to examine the proliferation of the cells. Real-time polymerase chain reaction, western blot, and immunocytochemistry were used to detect the CEC markers. Nd:YAG laser was used to establish an appropriate endothelium injury model based on rabbit corneas. The following intracameral injections were then performed to repair the model: 100 μL Opti-MEM I reduced serum medium (model group), 2 × 105 UCB EPCs diluted in 100 μL Opti-MEM I reduced serum medium (EPC group), 100 μM Y-27632 diluted in 100 μL Opti-MEM I reduced serum medium (Y-27632 group), and 2 × 105 UCB EPCs supplemented with 100 μM Y-27632 (final volume 100 μL, EPC/Y-27632 group). The follow-up tests focused on corneal transparency, central corneal thickness, intraocular pressure, and in vivo confocal microscopy, which were performed to evaluate the healing of the wounds.

RESULTS

Culturing UCB EPCs in CM supplemented with 10 μM Y-27632 resulted in higher proliferation rates compared with EGM-2 media and CM. There were significantly improved protein levels of Zona Occludens 1, N-cadherin, Na+-K+-ATPase α1, Na+-K+-ATPase β1, and Pax6 and improved mRNA levels of collagen type IV and VIII and AQP1. The combined intracameral injection of Y-27632 and UCB EPCs accelerated the recovery of corneal transparency, regression of corneal edema, and healing of the corneal endothelium compared with the injections of Y-27632 and UCB EPCs on their own.

CONCLUSIONS

Y-27632 not only promotes the proliferation of UCB EPCs but also contributes to differentiation of UCB EPCs toward CECs in the presence of CM. The intracameral injection of Y-27632 itself promotes the healing of corneal endothelium wounds. On this basis, supplementing UCB EPCs with Y-27632 accelerates the healing of corneal endothelium wounds.

Overall clinical outcomes of Descemet membrane endothelial keratoplasty in 600 consecutive eyes: A large retrospective case series

Purpose:

To analyze the overall clinical outcomes of Descemet membrane endothelial keratoplasty (DMEK) in 600 consecutive cases.

Methods:

Retrospective, consecutive interventional case series operated by a single surgeon. Six hundred consecutive eyes of 524 patients with endothelial dysfunctions of different etiologies scheduled for DMEK were included in this study. All donor tissues were prepared by the operating surgeon during the procedure, using McCarey Kaufman medium or Cornisol-preserved cornea with endothelial cell density (ECD) of ≥2500 cells/mm². Indications, postoperative best spectacle-corrected visual acuity (BSCVA), ECD, endothelial cell loss (ECL), and complications were analyzed postoperatively between 3 months and 2 years.

Results:

The commonest indication was post-cataract corneal edema/bullous keratopathy in 262 (43.7%) eyes followed by Fuchs′ endothelial corneal dystrophy 218 (36.3%). Vision affected comorbidities were present in 91 (15.2%) eyes. In phakic eyes with cataract (222; 37%), DMEK was combined with cataract surgery (Triple-DMEK). BSCVA of ≥20/25 was achieved in 41.0%, 46.4%, 49.2%, and 48.7% of eyes at 3, 6, 12, and 24 months, respectively and stabilized at 6 months (P = 0.54). Mean ECD decreased from 2884 ± 178 cells/mm² (n = 600) before surgery to 2223 ± 321 (n = 597), 2099 ± 354 (n = 524), 1918 ± 373 (n = 374), and 1772 ± 439 cells/mm² (n = 158) at 3, 6, 12, and 24 months respectively. The corresponding mean ECL was 22.9 ± 11.4%, 27.2 ± 12.4%, 33.5 ± 13.0%, and 38.6 ± 14.3%, respectively (P < 0.05 for all-time points). The commonest complication was DM detachment in 59 (9.8%) eyes of which 23 (3.8%) eyes required rebubbling. Three (0.5%) eyes had primary graft failure. Endothelial rejection occurred in 7 (1.2%) eyes until the last follow-up.

Conclusion:

DMEK is a safe and effective procedure in different types of endothelial diseases with encouraging surgical and clinical outcomes. Complications are less and ECL percentage up to 2 years is acceptable.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Descemet Membrane Endothelial Keratoplasty and Bowman Layer Transplantation: An Anatomic Review and Historical Survey

For nearly a century, the definitive treatment of many corneal dystrophies and ectactic disorders was limited to penetrating keratoplasty, but over the past 2 decades, a surge of surgical innovation has propelled the treatment of many corneal diseases to more targeted approaches with significantly better visual outcomes. Anterior stromal diseases were first changed through endothelial-sparing techniques, such as deep anterior lamellar keratoplasty, but have more recently transitioned to stromal-sparing approaches. Ultraviolet corneal crosslinking strengthens the cornea and halts progression of keratoconus in >90% of cases. Intracorneal ring segment and corneal allogenic ring segment implantation offer methods to flatten ectatic corneas. However, Bowman layer transplantation - inlay and more recently onlay techniques - has shown promise for treating advanced keratoconus and preventing keratoplasty. The advent of endothelial keratoplasty radically changed the treatment of corneal endothelial dysfunction, and Descemet membrane endothelial keratoplasty specifically offers an average postoperative visual acuity of 20/25 (0.8) with only 8.8% of grafts requiring retransplantation in the first 5 years. Here, we review the rapid innovations for surgical treatment of corneal diseases, spanning from endothelial keratoplasty and endothelial regeneration to anterior lamellar keratoplasty and stromal augmentation, highlighting key steps which may be moving us closer to a "postkeratoplasty" world.

Long-term outcomes of Descemet stripping automated endothelial keratoplasty for bullous keratopathy after argon laser iridotomy

PURPOSE

To report the long-term outcomes of Descemet stripping automated endothelial keratoplasty (DSAEK) for bullous keratopathy secondary to argon laser iridotomy (BK-ALI).

STUDY DESIGN

Retrospective chart review.

METHODS

Forty-five eyes from 41 consecutive patients with BK-ALI who underwent DSAEK from July 2007 to December 2013 were retrospectively analyzed. Best spectacle-corrected visual acuity (BCVA), endothelial cell density (ECD), and any complications were investigated over a 10-year postoperative period.

RESULTS

The mean BCVA improved from 0.80 logMAR before DSAEK to 0.28 logMAR at 6 months after DSAEK; the mean values showed an additional slight improvement between 6 months and 10 years after the surgery (P < .01). The mean ECD decreased from 2864 cells/mm² at baseline to 2269 cells/mm² (20.8% loss) at 6 months post-DSAEK, and this decreasing trend continued throughout the 10 years after DSAEK (P < .01). The mean ECD was 1148 cells/mm² (59.9% loss) after 5 years, and 568 cells/mm² (80.2% loss) after 10 years. No graft deaths were observed throughout the 10-year period (5-year follow-up rate 60.0%, 10-year follow-up rate 20.0%).

CONCLUSIONS

The 10-year outcomes of DSAEK for BK-ALI were excellent with a high graft survival rate.

PTEN Inhibition Accelerates Corneal Endothelial Wound Healing through Increased Endothelial Cell Division and Migration

Purpose

To investigate the role of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) in the regulation of corneal endothelial cell (CECs) focusing on proliferation and migration, and to further evaluate the application of PTEN inhibitors in the treatment of corneal endothelial dysfunction in a rat model.

Methods

Expression of PTEN in human and rat corneal endothelium was determined by immunocytochemistry, western blotting, and ELISA. A small molecular inhibitor of PTEN, bpV(pic), was applied in the culture of human CEC cell line B4G12 and organ-cultured rat cornea in the presence of transforming growth factor beta 2 (TGF-β2). Cell cycle status was detected by flow cytometry and BrdU staining. Subcellular localization for endogenous p27Kip1 was detected by immunocytochemistry and western blotting. Moreover, exogenous transfected YFP-p27Kip1 was observed under a fluorescent microscope. Cell migration was examined with a wound scratch model and transwell invasion assay. Finally, bpV(pic) was intracamerally injected in a rat corneal endothelial injury model. The wound healing process was evaluated by slit lamp biomicroscopy, optical coherence tomography, histological and scanning electron microscope examination.

Results

The expression of PTEN in human corneal endothelium was higher compared with rat, which we speculate was mostly responsible for the relatively less proliferation capacity of human CEC than rat. PTEN inhibition by bpV(pic) could reverse TGF-β2-induced CEC G1-arrest by alleviating p27Kip1 nuclear accumulation and decreasing total p27Kip1 expression. In addition, bpV(pic) promoted CEC migration, which acted synergistically with TGF-β2. Finally, intracameral injection of bpV(pic) could promote corneal endothelial wound healing in a rat model.

Conclusions

Our study provided experimental basis for the development of therapeutic agent targeting on PTEN for the treatment of corneal endothelial dysfunction.

Outcomes of rebubbling for graft detachment after Descemet's stripping endothelial keratoplasty or Descemet's stripping automated endothelial keratoplasty

Purpose

To study the outcomes of rebubbling for graft detachment after Descemet's stripping endothelial keratoplasty (DSEK) or Descemet's stripping automated endothelial keratoplasty (DSAEK).

Methods

From 2260 eyes that underwent DSEK or DSAEK from July 2008 to June 2015, 80 eyes of 80 patients developed graft detachment and were retrospectively reviewed. Host-related, surgery-related and donor-related factors that have a bearing on graft adhesion were looked at retrospectively, and eventual outcomes after rebubbling procedure were studied.

Results

Successful attachment was observed in 77 (96.25%) eyes and clear grafts were achieved in 55 (68.75%) eyes, while 25 (31.25%) eyes had graft failure. The uncorrected and best-corrected distance visual acuities significantly improved from 1 month to 3 months post-operatively and remained stable till 12 months of follow-up. Three lenticules that failed to attach with the first rebubbling procedure underwent a second rebubbling, two underwent a repeat DSEK with good outcomes and four underwent penetrating keratoplasty. On evaluating possible risk factors for graft failure, lower donor endothelial cell density was found to be a significant factor (P = 0.03). The median graft survival following rebubbling was 30 months.

Conclusion

Rebubbling procedure in detached grafts after DSEK or DSAEK can reattach the lenticule in 96% of eyes in immediate post-operative period and the majority of the grafts remained clear on long-term follow-up with a median graft survival period of 2.5 years.

Impact of Re-bubbling after Descemet Membrane Endothelial Keratoplasty on Long-term Results

Purpose/Aim of the study: Graft detachment after DMEK can be treated easily with an additional air injection - re-bubbling. The aim of our study was to investigate the effect of a re-bubbling on the postoperative outcome.Materials and Methods: In this retrospective, comparative, cohort study we included eyes from patients that underwent DMEK surgery. A graft detachment was diagnosed by slit-lamp examination and OCT scan. All eyes were divided into three groups: no re-bubbling, one re-bubbling, more than one re-bubbling. We analyzed the visual acuity, endothelial cell density and rate of graft failure.Results: In 163 of 463 eyes (35.2%) a re-bubbling was performed (119 eyes 1 re-bubbling, 44 eyes more than one re-bubbling). Visual acuity improved significantly in all groups. After controlling for donor age, reason for surgery, time of cultivation of the graft and preoperative visual acuity, no difference in the visual acuity was seen at any point of follow-up. All patients showed a significant reduction in endothelial cell density 1 month after DMEK. Controlling for donor age, reason for surgery, type of surgery (DMEK-only or DMEK combined with cataract surgery) and the time of cultivation of the graft, the difference in endothelial cell density at 1 month post-surgery between no re-bubbling and one re-bubbling was 157 cells/mm² (95% CI 2-310, p = .047) and between no re-bubbling and more than one re-bubbling 504 cells/mm² (95% CI 267 - 741, p < .001). The difference in endothelial cell density remained over the course of follow-up. Twenty patients (4.3%) developed a graft failure during postoperative follow-up. Controlling for donor age, reason for surgery and the time of cultivation of the graft, we did not find any difference in the risk of graft failure between re-bubbling categories.Conclusions: Re-bubbling increased the risk for an endothelial cell loss, but did not influence the postoperative visual acuity and the rate of graft failure.

The Need for Improved Therapeutic Approaches to Protect the Cornea Against Chemotoxic Injuries

Cornea, a highly specialized transparent tissue, is the major refractive element of the eye. The cornea is highly susceptible to chemotoxic injury through topical exposure to vapors, microparticles, and aqueous drops, as well as through systemically absorbed chemicals that access the cornea via tear film, aqueous humor, and limbal vasculature. Corneal injury activates a carefully orchestrated series of repair processes capable of resolving minor lesions over time, but it often fails to overcome the menace of moderate, severe, and chronic injuries and secondary pathophysiologies that permanently impair vision. The most serious complications of chemical injuries-persistent corneal edema, neovascularization, scarring/haze, limbal stem cell deficiency, and corneal melting-often manifest over months to years, suggesting that a better understanding of endogenous regenerative mechanisms of corneal repair can lead to the development of improved treatments that may attenuate or prevent corneal defects and protect vision.

Comparison of Intraocular Pressure, Usage of Topical Steroids, Need for Intraocular Pressure Lowering Drops, and Incidence of Glaucoma Surgery Up to 2 Years After Penetrating Keratoplasty and Endothelial Keratoplasty

PRECIS

A retrospective review of 239 eyes comparing intraocular pressure (IOP), steroid needs, IOP-lowering drop needs, and incidence of glaucoma surgery between endothelial keratoplasty and penetrating keratoplasties (PKP) at multiple timepoints postoperatively up to 2 years.

PURPOSE

The purpose of this study was to compare postoperative IOP, steroid use, IOP-lowering drop use, and need for glaucoma surgery between PKP, Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSEK).

MATERIALS AND METHODS

A retrospective chart review of all PKP, DMEK, and DSEK surgeries was performed between July 1, 2012 and July 1, 2017 at the University of California, Irvine. Patients with a prior history of glaucoma, corneal or glaucoma surgery, concurrent major or emergent surgery, active infection, and eye disease with synechiae were excluded. A total of 239 patients who underwent PKP (N=127), DMEK (N=46), or DSEK (N=66) were included. IOP, steroid use, IOP-lowering drop use, and need for glaucoma surgery were compared at postoperative day 1, postoperative week 1 (POW1), and postoperative month 1 to 24 (POM1-24).

RESULTS

IOP for PKP was higher than DMEK and DSEK at POW1, POM1, POM6, and POM24 (P<0.05). IOP for PKP was higher than DMEK at POM12 (P=0.028). There was no significant difference in IOP between DMEK and DSEK for all timepoints. PKP required more steroids than DSEK and DMEK at POM3, POM6, POM12, and POM24 (P<0.05). More IOP-lowering drops were required for DSEK than DMEK and PKP at postoperative day 1 and POW1 (P<0.05). More IOP-lowering medications were used for DSEK than DMEK at POM3 and POM12 (P<0.05). About 6% to 7% of patients needed glaucoma surgery by POM24.

CONCLUSIONS

Endothelial keratoplasties had decreased IOP and steroid needs compared with PKPs postoperatively up to 2 years. The rate of glaucoma surgery and IOP-lowering drop needs were similar between the groups.

Tissue engineered ultra-thin descemet stripping corneal endothelial layers using porcine cornea and stem cells

Due to their very poor proliferative capacity, the dysfunction of corneal endothelial cells can sometimes lead to incurable eye diseases that require corneal transplantation. Although many studies have been performed to reconstruct corneal endothelial cells, corneal transplantation is still considered to be the established approach. In this study, we developed bio-engineered Descemet stripping endothelial (DSE) layers, using porcine cornea and induced pluripotent stem cell (iPSC)-derived corneal endothelial cells (iCECs). First, we optimized a protocol to prepare an ultra-thin and decellularized Descemet stripping (DS) scaffold from porcine cornea. Our DS layers show over 90% transparency compared to the control. Porcine-derived cells and xenogenic antigens disappeared, whereas the collagen matrix remained in the graft. Next, corneal endothelial cell lines or iCECs were seeded on the decellularized DS graft and cultured for 7 days. The drying method reduced graft rolling and edema, and increased transparency during culture. The reseeded cells were evenly distributed over the graft, and most of the cells survived. Although future clinical studies are warranted, engineered DSE tissues using xenogenic tissues and stem cells will be useful tools for the treatment of incurable corneal diseases.

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.

Graft survival and endothelial outcomes after penetrating keratoplasty and Descemet stripping automated endothelial keratoplasty: A systematic review and meta-analysis

The present study aimed to compare the outcomes of graft survival, endothelial cell loss and vision improvement between penetrating keratoplasty (PK) and Descemet stripping automated endothelial keratoplasty (DSAEK) for treating corneal endothelium diseases. The PubMed, CENTRAL (Cochrane) and Embase databases were searched for records added until September 20, 2019. The studies considered were two-arm prospective and retrospective studies comparing outcomes of interest between PK and DSAEK. Ultimately, 10 studies were included with a total of 2,634 patients (910 eyes treated with DSAEK; 1,804 eyes treated with PK). Assessment of the summary effect by meta-analysis suggested that, compared with PK treatment, DSAEK was associated with a greater improvement from baseline in best spectacle-corrected visual acuity [difference (diff.) in means of change from baseline=-0.225, 95% CI=-0.341 to -0.109, P<0.001] and a reduced loss of endothelial cell density (diff. in means=-292.05 cells/mm², 95% CI=-419.53 to -146.57 cells/mm², P<0.001). Graft survival rates were similar using either PK or DSAEK (odds ratio=1.005, 95% CI=0.329-3.071, P=0.993). The overall results suggested that DSAEK may have an advantage over PK for corneal endothelial dysfunction in terms of the visual acuity outcome. The absence of definite time frames in the comparisons limits the conclusions on endothelial cell loss and graft survival.

Protective Effects Oncorneal Endothelium During Intracameral Irrigation Using N-(2)-l-alanyl-l-Glutamine

Corneal endothelial disease is a global sight-threatening disease, and corneal transplantation using donor corneas remains the sole therapeutic option. A previous work demonstrated that N (2)-alanyl-glutamine (Ala-Gln) protected against apoptosis and cellular stress, and maintained intestinal tissue integrity. In this pursuit, the present study aimed to examine the effect of Ala-Gln in the protection of the corneal endothelium and expand its range of potential clinical applications. Mice in the control group were intracamerally irrigated with Ringers lactate injection, whereas those in the experimental group were irrigated with Ringers lactate injection containing Ala-Gln. The mean intraocular pressure increased to 44 ± 3.5 mm Hg during intracameral irrigation (normal range 10.2 ± 0.4 mmHg). In vivo confocal microscopy results showed that the addition of Ala-Gln protected the morphology, structure, and density of the corneal endothelial cells. Optical Coherence Tomography (OCT) measurements showed that corneal thickness was not significantly different between the two groups, because of the immediate corneal edema after irrigation, but the addition of Ala-Gln obviously promoted the recovery of the corneal edema. Scanning electron microscopy indicated that the corneal endothelial cells were severely ruptured and exfoliated in the Ringer’s group accompanied with cellular edema, when compared with the Ala-Gln group. The intracameral irrigation using Ala-Gln protected the structure and expression of cytoskeleton and Na-K-ATPase, which exhibited a regular distribution and significantly increased expression in comparison to Ringer’s group. Furthermore, Ala-Gln maintained the mitochondrial morphology and increased the activity of mitochondria. Moreover, transmission electron microscopy showed that intracameral irrigation of Ala-Gln reversed the ultrastructural changes induced by the acute ocular hypertension in mice. Our study demonstrates that the intracameral irrigation of Ala-Gln effectively maintained the corneal endothelial pump function and barrier function by protecting the mitochondrial function and preventing the rearrangement of cytoskeleton in acute ocular hypertension in mice.

Resolution of Corneal Fibrosis After Descemet's Stripping Automated Endothelial Keratoplasty: A Case Report

Purpose

To report the resolution of anterior corneal fibrosis after Descemet’s stripping automated endothelial keratoplasty (DSAEK), in a patient with chronic corneal edema and anterior stromal scarring.

Methods

A 63-year-old woman, with a history of Fuchs endothelial dystrophy, presented with increasing discomfort and gradual visual loss in her right eye. Clinical examination revealed long-standing bullous keratopathy accompanied by marked subepithelial fibrosis (SEF). Based on the low postoperative visual potential due to glaucomatous optic neuropathy, we decided to proceed with DSAEK.

Results

During the follow-up period, SEF was found to gradually resolve. Corneal clarity was restored and an improvement in visual acuity was observed up to 12 months after surgery.

Conclusion

DSAEK alone may represent an effective therapeutic option for the restoration of impaired corneal clarity in patients with long-standing corneal edema and concomitant anterior subepithelial scarring.

Revisiting Existing Evidence of Corneal Endothelial Progenitors and Their Potential Therapeutic Applications in Corneal Endothelial Dysfunction

PURPOSE

A recent successful clinical trial demonstrated that a less invasive cell-injection procedure is a viable medical modality for treating corneal endothelial dystrophy. This medical advance still relies on human corneal endothelial cell (HCEC) sources derived from rare cornea donations. The progenitor of the corneal endothelium, which has the characteristics of active proliferation and lineage restriction, will be an ideal cell source for expansion ex vivo. However, the distribution of progenitor-like cells in the corneal endothelial sheet has been under debate for more than a decade.

METHODS

This paper re-examines the scientific evidence of the existence of human corneal endothelial progenitors (HCEPs) from the aspects of (1) the origin of cornea formation during ocular development, (2) manifestations from clinical studies, and (3) the distinctive properties of ex vivo-cultured subpopulations.

RESULTS

The discrepancies regarding different types of progenitor-like cells in various locations of the cornea are based on the fact that the corneal endothelium is derived from different cell types with multiple origins during corneal formation.

CONCLUSIONS

Resolving this long-standing issue in corneal biology will enable various types of progenitors to be isolated and their potencies regarding the formation of functional endothelial cells to be examined. Additionally, an effective niche system for quantitatively producing therapeutic cells can be formulated to satisfy the burning need associated with corneal endothelial dystrophy in the future.

Clinical Outcomes of Penetrating Keratoplasty and Descemet Stripping Automated Endothelial Keratoplasty in Asian Population with American Corneas

To determine the comparative efficacy and safety of penetrating keratoplasty (PK) and Descemet stripping automated endothelial keratoplasty (DSAEK) in the Asian population receiving imported donor corneas, our single-center retrospective study provides analysis supporting the transition from PK to DSAEK in the Asian population using imported American donor corneas. We analyzed 259 patients with 241 and 57 cases of PK and DSAEK respectively during 2008 to 2017 using imported corneas at Chang Gung Memorial Hospital, Linkou, Taiwan. In terms of long-term graft survival analysis, there was no difference between PK and DSAEK (log-rank p = 0.386, HR = 0.920, 95% CI: [0.641–1.380]). However, Cox proportional regression analysis revealed that corneal survival rate of DSAEK group in the first 100 days after transplantation was inferior than that of PK group (log-rank p < 0.001, HR = 2.733, 95% CI: [1.501–4.977])]. Despite the inferior survival rate, there were significantly less neovascularization and Descemet membrane folds in the DSAEK group. Importantly, the non-complication rate of DSAEK was much higher than that of PK with significant difference (PK, 25.7% vs. DSAEK 42.0%, p = 0.022). Collectively, DSAEK is suggested as an alternative surgical modality in Asian patients using imported American donor corneas because of less complication, and no difference in long-term corneal graft survival rates between PK and DSAEK.

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

Purpose

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

Patients and methods

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

Results

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

Conclusion

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

Impact of venting incision on graft detachment in Descemet stripping automated endothelial keratoplasty

PURPOSE:

To evaluate the impact of venting incision on graft detachment in Descemet stripping automated endothelial keratoplasty (DSAEK).

MATERIALS AND METHODS:

Retrospective comparative study on DSAEK procedure performed with (n = 13) and without (n = 39) venting incision. Patients were treated with DSAEK for various causes of endothelial decompensation between February 2014 and April 2016. The rate of postoperative graft detachments documented on anterior segment optical coherence tomography was compared in both groups.

RESULTS:

Paracentral venting incision decreases the rate of graft displacement. Non-venting group (nvg) had 28.2% graft displacement compared to venting group (vg) which had 7.6% graft displacement.

CONCLUSION:

Venting incision is a simple and safe manoeuvre to facilitate graft adherence in DSAEK, especially in caseswith presence of high-risk factors for graft detachment.

Automated 2D-3D quantitative analysis of corneal graft detachment post DSAEK based on AS-OCT images

BACKGROUND AND OBJECTIVE

In current ophthalmological practices, assessment of graft condition post Descemet's stripping automated endothelial keratoplasty (DSAEK) is performed qualitatively using few (four) anterior-segment optical coherence tomography (AS-OCT) radial B-scans. From those scans, clinicians need to mentally synthesize the graft in 3D, and estimate its overall condition. In contrast, quantitative representation of 360° thickness profile would facilitate better visualization of graft condition, and hence medical decision making. Consequently, clinicians seek to quantify potential detachments in 3D from the aforementioned sparse B-scans. Against this backdrop, aiming to assist doctors in making an accurate postoperative assessment, we attempted at 3D visualization and quantification of donor lenticule separation (DLS) using only four AS-OCT radial B-scans.

METHODS

We developed an automated methodology to model and quantify DLS in 3D using only four AS-OCT B-scans. Firstly, we demonstrated that detachment can be viewed as a tubular vessel-like structure and hence can be detected using Hessian matrix analysis. Secondly, a two-stage interpolation was employed for determining the 3D profile of the detachment. Finally, various clinically significant parameters including type of separation (communicative and non-communicative), volume and 360° thickness profile of the detachment, thickness (central and peripheral) of the recipient cornea and donor graft were also obtained. Accuracy of the proposed algorithm was substantiated via thorough statistical analysis, specifically, vis-á-vis intra- and inter-observer repeatability using Dice coefficient (DC).

RESULTS

On twenty seven eyes of 27 patients (male and female), four radial OCT B-scans with 45° angular separation taken per eye, proposed algorithm found that donor graft detached completely in 3 eyes and detached one side (communicative) in remaining 24 eyes which is in agreement with expert's opinion. Quantitatively, proposed algorithm achieves a mean DC of 81.35% with manual reference which is close to the corresponding inter-observer repeatability value of 86.77%. Volume estimation of the detachment indicates that 11 eyes had 0-25%, 9 had 25-50%, 5 had 50-75% and 2 had 75-100% detachment.

CONCLUSIONS

Accuracy of the proposed methodology was corroborated vis-à-vis observer delineation. This model of image analysis may aid in prognostication of graft outcome in patients with graft detachment after DSAEK.

Comparison of Artificial Anterior Chamber Internal Pressures and Cutting Systems for Descemet's Stripping Automated Endothelial Keratoplasty

Purpose

To optimize methods of preparing donor cornea tissue for Descemet's stripping automated endothelial keratoplasty (DSAEK), we compared five experimental conditions with different internal pressures and cutting systems.

Methods

The artificial anterior chamber internal pressure (IP) was set at 100 or 200 mm Hg. The microkeratome cut was performed with or without an artificial chamber pressurizer (ACP), using a CBm turbine (CBm) or one use-plus automated (OUP-A). Thirty human research corneas were divided into five groups, and compared after the cut with donor tissue quality parameters, including cutting depth, graft uniformity, cell evaluation, and smoothness of the stromal surface.

Results

The smallest variation in mean cut depth was observed in the condition, which had IP of 200 mm Hg used ACP and OUP-A. In experimental groups cut using CBm, significantly more consistent thicknesses were made at an IP of 200 than 100 mm Hg. There were no statistically significant differences among the groups in either endothelial cell density or cell viable assay results after cuts. Using an IP of 200 mm Hg with ACP and CBm produced the roughest stromal surface, and the roughness grading scores showed a positive correlation with the percentage of cut depth.

Conclusions

An IP of 200 mm Hg was the best setting for DSAEK grafts with high predictability of cut depth and uniformity of graft thickness without endothelial cell damage.

Translational Relevance

For successful DSAEK, it is recommended that a set internal pressure of 200 mm Hg be used during microkeratome cutting for donor tissue preparation.

A Review of the Emerging Role of Silk for the Treatment of the Eye

Silk is a remarkable biopolymer with a long history of medical use. Silk fabrications have a robust track record for load-bearing applications, including surgical threads and meshes, which are clinically approved for use in humans. The progression of top-down and bottom-up engineering approaches using silk as the basis of a drug delivery or cell-loaded matrix helped to re-ignite interest in this ancient material. This review comprehensively summarises the current applications of silk for tissue engineering and drug delivery, with specific reference to the eye. Additionally, the review also covers emerging trends for the use of silk as a biologically active biopolymer for the treatment of eye disorders. The review concludes with future capabilities of silk to contribute to advanced, electronically-enhanced ocular drug delivery concepts.

Visual Outcomes of Ultrathin-Descemet Stripping Endothelial Keratoplasty versus Descemet Stripping Endothelial Keratoplasty

Purpose

To examine the impact of graft thickness (GT) on postoperative visual acuity and endothelial cell density after ultrathin-Descemet stripping automated endothelial keratoplasty (UT-DSAEK) versus conventional DSAEK.

Methods

The medical records of all patients who underwent DSAEK at our institute during a 2-year period were reviewed. After excluding subjects with low visual potential, 34 eyes were divided into two groups based on the postoperative GT as measured with anterior segment optical coherence tomography (AS-OCT): an UT-DSAEK group (GT ≤ 100 μm, n=13 eyes) and a DSAEK group (GT > 100 μm, n=21 eyes). The groups were compared with regard to best-corrected visual acuity (BCVA), subjective refraction, central corneal thickness (CCT), GT, and endothelial cell density (ECD).

Results

Preoperative BCVA (logMAR) was 1.035 ± 0.514 and 0.772 ± 0.428 for UT-DSAEK and DSAEK, respectively (P=0.072). At 6 months postoperatively, BCVA was 0.088 ± 0.150 following UT-DSAEK and 0.285 ± 0.158 following DSAEK (P=0.001).

Conclusion

DSAEK grafts with a thickness under 100 μm offered better visual outcomes during the early postoperative period.

Outcomes of Descemet Membrane Endothelial Keratoplasty (DMEK) Using Surgeon's Prepared Donor DM-Roll in Consecutive 100 Indian Eyes

Background:

Descemet Membrane Endothelial Keratoplasty (DMEK) is now becoming the popular form of endothelial keratoplasty using only donor DM with healthy endothelium as true component lamellar corneal surgery.

Objective:

To analyze the results of visual outcomes, endothelial cell loss and complications of Descemet membrane endothelial keratoplasty in first consecutive 100 Indian eyes.

Methods:

100 eyes of 95 consecutive patients with endothelial dysfunctions of different etiologies scheduled for DMEK, were included in this study. In each case, surgeon prepared tissue using McCarey Kaufman medium- or Cornisol-preserved donor cornea with a cell count of ≥2500 cells/mm². Surgical complications, Best Spectacle Corrected Visual Acuity (BSCVA); Endothelial Cell Density (ECD) and Endothelial Cell Loss (ECL) were analyzed for each patient after a minimum follow-up of three months.

Results:

The Main indication was pseudophakic corneal edema or bullous keratopathy in 52 (52%) eyes. 38 (38%) eyes had Fuchs′ dystrophy with various grades of cataract. In 43 phakic eyes, DMEK was combined with cataract surgery and intraocular lens implantation. Mean DM-roll preparation time was 7.5 ± 2.8 min and in 3 eyes, DM-graft were damaged. After 3-months, BSCVA was ≥20/25 in 57 (57.6%) cases. Mean ECD was 2123 ± 438/mm² (range: 976 - 3208/ mm²) and the mean endothelial cell loss after 3-months was 26.92 ± 13.40 (range: 4.90 - 66.6%). Partial DM detachment occurred in 8 (8.0%) eyes and rebubbling required in 4 eyes. Iatrogenic primary graft failure occurred in one eye.

Conclusion:

Descemet membrane endothelial keratoplasty is a safe and effective procedure in several types of endothelial diseases among Indian patients with encouraging surgical and visual outcomes. Complications are less and endothelial cell loss percentage is acceptable.

Descemet Membrane Endothelial Keratoplasty: Outcomes in the First Year of Experience

OBJECTIVES

We aimed to report the clinical outcomes of Descemet membrane endothelial keratoplasty in our first year of experience.

MATERIALS AND METHODS

Patients who underwent Descemet membrane endothelial keratoplasty at the Baskent University Faculty of Medicine, Department of Ophthalmology, between 2015 and 2016 were included in the study. Patient demographics, cause of endothelial dysfunction, best-corrected visual acuity, central corneal thickness, graft survival, follow-up duration, and intraoperative and postoperative complications were recorded.

RESULTS

Five eyes of 5 patients (4 female, 1 male) with a mean age of 53.4 ± 12.7 years were included. Cause of endothelial dysfunction included corneal endothelial dystrophy in 3 patients, pseudophakic bullous keratopathy in 1 patient, and endothelial graft failure after previous penetrating keratoplasty in 1 patient. Pre-stripped Descemet membranes obtained from the Ankara State Hospital Eye Bank were used. Mean duration of postoperative follow-up was 7.4 ± 3.7 months. Mean preoperative Snellen best-corrected visual acuity and central corneal thickness were 0.24 ± 0.15 and 625.5 ± 97.4 μm. Mean best-corrected visual acuity increased to 0.67 ± 0.26 (P = .02) in the first month and to 0.84 ± 0.11 (P < .01) at the end of follow-up. Mean central corneal thickness decreased to 546.6 ± 28.4 μm (P = .03). Graft detachment was observed in 1 patient on the first postoperative day, and it was reattached successfully by injection of air into the anterior chamber. There were no intraoperative complications. All corneas were clear at the end of follow-up.

CONCLUSIONS

Descemet membrane endothelial keratoplasty provides a new and exciting option for endothelial transplant and has the potential to become the primary procedure for surgical management of Fuchs endothelial dystrophy and corneal endothelial disease. Rapid visual rehabilitation with few and manageable complications and good visual outcomes are the major advantages of this procedure.

Feasibility of cell-based therapy combined with descemetorhexis for treating Fuchs endothelial corneal dystrophy in rabbit model

Corneal transparency is maintained by the corneal endothelium through its pump and barrier function. Severe corneal endothelial damage results in dysregulation of water flow and eventually causes corneal haziness and deterioration of visual function. In 2013, we initiated clinical research of cell-based therapy for treating corneal decompensation. In that study, we removed an 8-mm diameter section of damaged corneal endothelium without removing Descemet’s membrane (the basement membrane of the corneal endothelium) and then injected cultured human corneal endothelial cells (CECs) into the anterior chamber. However, Descemet’s membrane exhibits clinically abnormal structural features [i.e., multiple collagenous excrescences (guttae) and thickening] in patients with Fuchs endothelial corneal dystrophy (FECD) and the advanced cornea guttae adversely affects the quality of vision, even in patients without corneal edema. The turnover time of cornea guttae is also not certain. Therefore, we used a rabbit model to evaluate the feasibility of Descemet’s membrane removal in the optical zone only, by performing a small 4-mm diameter descemetorhexis prior to CEC injection. We showed that the corneal endothelium is regenerated both on the corneal stroma (the area of Descemet’s membrane removal) and on the intact peripheral Descemet’s membrane, based on the expression of function-related markers and the restoration of corneal transparency. Recovery of the corneal transparency and central corneal thickness was delayed in areas of Descemet’s membrane removal, but the cell density of the regenerated corneal endothelium and the thickness of the central corneal did not differ between the areas with and without residual Descemet’s membrane at 14 days after CEC injection. Here, we demonstrate that removal of a pathological Descemet’s membrane by a small descemetorhexis is a feasible procedure for use in combination with cell-based therapy. The current strategy might be beneficial for improving visual quality after CEC injection as a treatment for FECD.

Effect of venting incisions on graft attachment in Descemet's stripping automated endothelial keratoplasty

Purpose

To investigate the impact of venting incisions on the adherence of graft to the recipient's stroma in Descemet's stripping automated endothelial keratoplasty (DSAEK).

Methods

Fifty-six patients were enrolled in this study. Patients were randomly allocated into two groups. Twenty-eight patients had a DSAEK procedure with venting incisions. The second group was treated by conventional DSAEK with no venting incisions. Slit-lamp examination and anterior segment optical coherence tomography (AS-OCT) were performed in day one and 14 days after surgery to investigate graft attachment. The thickness of cornea and lenticle were also evaluated by AS-OCT. BCVA (logMAR) was measured the day before the surgery and 14 days postoperatively.

Results

Subclinical graft detachment in the first day after surgery was significantly lower in patients who had a DSAEK procedure and venting incisions (P = 0.02), but no difference was noted in the rate of clinical graft detachment on day one (P = 0.24) and subclinical and clinical graft detachment on day 14 (P = 0.24, P = 0.50, respectively). The thickness of the cornea and lenticle after the surgery were statistically similar between the two groups (P = 0.903, P = 0.402, respectively). No difference in the improvement of BCVA was observed between the venting and non-venting group (P = 0.143).

Conclusions

Routine use of venting incisions may not be necessary in the standard DSAEK procedures. More studies with larger sample sizes are needed to better confirm the results of this study.

Angiogenesis and lymphangiogenesis in corneal transplantation-A review

Corneal transplantation has been proven effective for returning the gift of sight to those affected by corneal disorders such as opacity, injury, and infections that are a leading cause of blindness. Immune privilege plays an important role in the success of corneal transplantation procedures; however, immune rejection reactions do occur, and they, in conjunction with a shortage of corneal donor tissue, continue to pose major challenges. Corneal immune privilege is important to the success of corneal transplantation and closely related to the avascular nature of the cornea. Corneal avascularity may be disrupted by the processes of angiogenesis and lymphangiogenesis, and for this reason, these phenomena have been a focus of research in recent years. Through this research, therapies addressing certain rejection reactions related to angiogenesis have been developed and implemented. Corneal donor tissue shortages also have been addressed by the development of new materials to replace the human donor cornea. These advancements, along with other improvements in the corneal transplantation procedure, have contributed to an improved success rate for corneal transplantation. We summarize recent developments and improvements in corneal transplantation, including the current understanding of angiogenesis mechanisms, the anti-angiogenic and anti-lymphangiogenic factors identified to date, and the new materials being used. Additionally, we discuss future directions for research in corneal transplantation.

Glaucoma after corneal replacement

Glaucoma is a well-known complication after corneal transplantation surgery. Traditional corneal transplantation surgery, specifically penetrating keratoplasty, has been slowly replaced by the advent of new corneal transplantation procedures: primarily lamellar keratoplasties. There has also been an emergence of keratoprosthesis implants for eyes that are high risk of failure with penetrating keratoplasty. Consequently, there are different rates of glaucoma, pathogenesis, and potential treatment in the form of medical, laser, or surgical therapy.

Effects of temperature and fluid media on the scroll width size of the Descemet's membrane endothelial keratoplasty (DMEK) donor graft

Aim

Our study was conducted to evaluate whether higher temperature leads to increased – or wider – scroll widths of the Descemet’s membrane endothelial keratoplasty (DMEK) donor graft.

Purpose

To investigate the effects of temperature and fluid media on the DMEK donor graft scroll widths.

Materials and methods

This research work was a laboratory investigation. Baseline cell count was taken via specular microscopy for the donor corneas at room temperature (20°C–25°C). The endothelium sides of the donor corneas were stained with Trypan Blue Solution 0.4% for 30 s, and the Descemet’s membranes were stripped. The DMEK donor grafts were placed into three different fluid media – Optisol^®, Balanced Salt Solution (BSS), and BSS PLUS^® (BSS Plus). The DMEK donor grafts were then transferred into cold temperature (4°C) for 60 min, after which the donor grafts’ scroll widths were examined and measured. The donor grafts were then warmed in the incubator and brought to physiological temperature (35°C–37°C), and their scroll widths were examined and measured again.

Results

In 30 measurements of ten tissues across three temperature and fluid conditions, the average scroll width measured 1.73 mm, ranging from 1.1 to 2.9 mm. In a mixed linear model, the scroll widths increased with temperature (P=0.02). There was no significant difference in scroll widths among the three solutions (P=0.84, mixed linear model).

Conclusion

We observed an increase in DMEK donor graft scroll widths with higher temperatures. The usage of BSS Plus as media solution could also lead to smaller DMEK donor graft scroll widths, compared with BSS, but our study does not establish this.