New trends in corneal transplants at the University of Toronto

Exploring single-cell RNA sequencing as a decision-making tool in the clinical management of Fuchs' endothelial corneal dystrophy

Single-cell RNA sequencing (scRNA-seq) has enabled the identification of novel gene signatures and cell heterogeneity in numerous tissues and diseases. Here we review the use of this technology for Fuchs' Endothelial Corneal Dystrophy (FECD). FECD is the most common indication for corneal endothelial transplantation worldwide. FECD is challenging to manage because it is genetically heterogenous, can be autosomal dominant or sporadic, and progress at different rates. Single-cell RNA sequencing has enabled the discovery of several FECD subtypes, each with associated gene signatures, and cell heterogeneity. Current FECD treatments are mainly surgical, with various Rho kinase (ROCK) inhibitors used to promote endothelial cell metabolism and proliferation following surgery. A range of emerging therapies for FECD including cell therapies, gene therapies, tissue engineered scaffolds, and pharmaceuticals are in preclinical and clinical trials. Unlike conventional disease management methods based on clinical presentations and family history, targeting FECD using scRNA-seq based precision-medicine has the potential to pinpoint the disease subtypes, mechanisms, stages, severities, and help clinicians in making the best decision for surgeries and the applications of therapeutics. In this review, we first discuss the feasibility and potential of using scRNA-seq in clinical diagnostics for FECD, highlight advances from the latest clinical treatments and emerging therapies for FECD, integrate scRNA-seq results and clinical notes from our FECD patients and discuss the potential of applying alternative therapies to manage these cases clinically.

Design and Biocompatibility of a Novel, Flexible Artificial Cornea

Purpose

We sought to introduce the materials, design, and biocompatibility of a flexible and suturable artificial corneal device.

Methods

Single-piece, fully synthetic, optic-skirt design devices were made from compact perfluoroalkoxy alkane. The skirt and the optic wall surfaces were lined with a porous tissue ingrowth material using expanded polytetrafluoroethylene. Full-thickness macroapertures around the skirt perimeter were placed to facilitate nutrition of the recipient cornea. Material properties including the skirt's modulus of elasticity and bending stiffness, optic light transmission, wetting behavior, topical drug penetrance, and degradation profile were evaluated.

Results

The final prototype suitable for human use has a transparent optic with a diameter of 4.60 mm anteriorly, 4.28 mm posteriorly, and a skirt outer diameter of 6.8 mm. The biomechanical and optical properties of the device closely align with the native human cornea with an average normalized device skirt-bending stiffness of 4.7 kPa·mm4 and light transmission in the visible spectrum ranging between 92% and 96%. No optical damage was seen in the 36 devices tested in fouling experiments. No significant difference was observed in topical drug penetrance into the anterior chamber of the device implanted eye compared with the naïve rabbit eye.

Conclusions

The flexibility and biocompatibility of our artificial cornea device may offer enhanced tissue integration and decreased inflammation, leading to improved retention compared with rigid keratoprosthesis designs.

Translational Relevance

We have developed a fully synthetic, flexible, suturable, optic-skirt design prototype artificial cornea that is ready to be tested in early human feasibility studies.

Evaluation of biophysical alterations in the epithelial and endothelial layer of patients with Bullous Keratopathy

The cornea is a fundamental ocular tissue for the sense of sight. Thanks to it, the refraction of two-thirds of light manages to participate in the visual process and protect against mechanical damage. Because it is transparent, avascular, and innervated, the cornea comprises five main layers: Epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. Each layer plays a key role in the functionality and maintenance of ocular tissue, providing unique ultrastructural and biomechanical properties. Bullous Keratopathy (BK) is an endothelial dysfunction that leads to corneal edema, loss of visual acuity, epithelial blisters, and severe pain, among other symptoms. The corneal layers are subject to changes in their biophysical properties promoted by Keratopathy. In this context, the Atomic Force Microscopy (AFM) technique in air was used to investigate the anterior epithelial surface and the posterior endothelial surface, healthy and with BK, using a triangular silicone tip with a nominal spring constant of 0.4 N/m. Six human corneas (n = 6) samples were used for each analyzed group. Roughness data, calculated by third-order polynomial adjustment, adhesion, and Young's modulus, were obtained to serve as a comparison and identification of morphological and biomechanical changes possibly associated with the pathology, such as craters and in the epithelial layer and exposure of a fibrotic layer due to loss of the endothelial cell wall. Endothelial cell membrane area and volume data were calculated, obtaining a relevant comparison between the control and patient. Such results may provide new data on the physical properties of the ocular tissue to understand the physiology of the cornea when it has pathology.

Estrogen genotoxicity causes preferential development of Fuchs endothelial corneal dystrophy in females

Fuchs endothelial corneal dystrophy (FECD) is a genetically complex, age-related, female-predominant disorder characterized by loss of post-mitotic corneal endothelial cells (CEnCs). Ultraviolet-A (UVA) light has been shown to recapitulate the morphological and molecular changes seen in FECD to a greater extent in females than males, by triggering CYP1B1 upregulation in females. Herein, we investigated the mechanism of greater CEnC susceptibility to UVA in females by studying estrogen metabolism in response to UVA in the cornea. Loss of NAD(P)H quinone oxidoreductase 1 (NQO1) resulted in increased production of estrogen metabolites and mitochondrial-DNA adducts, with a higher CEnC loss in Nqo1-/- female compared to wild-type male and female mice. The CYP1B1 inhibitors, trans-2,3',4,5'-tetramethoxystilbene (TMS) and berberine, rescued CEnC loss. Injection of wild-type male mice with estrogen (E2; 17β-estradiol) increased CEnC loss, followed by increased production of estrogen metabolites and mitochondrial DNA (mtDNA) damage, not seen in E2-treated Cyp1b1-/-male mice. This study demonstrates that the endo-degenerative phenotype is driven by estrogen metabolite-dependent CEnC loss that is exacerbated in the absence of NQO1; thus, explaining the mechanism accounting for the higher incidence of FECD in females. The mitigation of estrogen-adduct production by CYP1B1 inhibitors could serve as a novel therapeutic strategy for FECD.

Review for special issue: Corneal lamellar surgery: Present outcomes and future perspectives

Since the establishment of the first eye bank in the 1940s, their role has evolved to face new challenges. With the recent development of lamellar keratoplasties, eye banks play an even bigger role in the selection and preparation of donor tissues. The increasing number of keratoplasty techniques and the high demand for "ready-to-use" tissues are challenging eye banks to improve and develop new preparation techniques. Besides necessary examinations, new approaches of tissue analysis in eye banks allow a better/optimized selection of corneal tissues. These new challenges in tissue preservation, preparation, and selection are propelling eye banks into a new era of modern eye banking.

Descemet membrane endothelial keratoplasty combined with presbyopia-correcting and toric intraocular lenses - a narrative review

Fuchs endothelial corneal dystrophy (FECD) is the leading indication for EK and may coexist with cataract and presbyopia. Notably, the outcomes of phacoemulsification in FECD patients are not as favorable as those in eyes without this condition. Historically, only monofocal intraocular lenses (IOLs) were recommended for these patients. However, recent reports have described the implantation of Premium-IOLs (such as Multifocal IOLs, Enhanced Depth of Focus IOLs, and Toric IOLs) in FECD eyes undergoing cataract surgery and Descemet membrane endothelial keratoplasty (DMEK). While the results are encouraging, they are not as optimal as those from unoperated eyes, especially when comparing simultaneous procedures to sequential ones. It's advised to perform the DMEK first to improve the accuracy of IOL calculations. Still, even successfully operated eyes may experience secondary graft failure or graft rejection after DMEK. The success rate of a secondary DMEK is typically lower than that of the initial procedure. Furthermore, if the postoperative thickness after DMEK is less than anticipated, laser enhancements might not be an option. There's a pressing need for more controlled and randomized clinical trials to ascertain the safety and effectiveness of Premium-IOLs for FECD eyes. This narrative review aims to collate evidence on the use of Premium IOL technologies in eyes receiving EK and to underscore key points for surgeons performing EK combined with cataract surgery.

Indications and types of keratoplasties: Trends in the past 10 years (2011-2020) in Eastern India

Purpose

To observe the trends of various types of keratoplasties in different etiologies over a period of 10 years (2011-2020) in a tertiary eye care center of eastern India.

Methods

A retrospective review of patients undergoing keratoplasties from 2011 to 2020 was performed in a tertiary eye care hospital situated in eastern part of India. Apart from demographic data, primary indication for each surgery and type of procedure carried out was recorded. For comparison, data were divided into two time periods: Group I: Jan 2011 to Dec 2015 and Group II: Jan 2016 to Dec 2020.

Results

Over a period of 10 years, a total of 2365 (Group I: 902, Group II: 1463) keratoplasties were performed. The average age of patients was 45.8 ± 19.9 and 46.9 ± 20.9 years in Group I and Group II, respectively. Among all the corneal grafts, 1747 (74%) surgeries were full-thickness. Although optical penetrating keratoplasty (OPK) was most the common indication for full-thickness keratoplasties, Descemet's stripping endothelial keratoplasty (DSEK) remained most performed lamellar keratoplasty. Keratitis, corneal scars, and bullous keratopathies remain to be most common indications in both groups. Number of lamellar keratoplasties increased significantly from Group I to Group II for corneal scars (P = 0.02), bullous keratopathies (P = 0.01), and endothelial dystrophies (P = 0.00).

Conclusion

With change in time, the indication and technique of keratoplasty has witnessed a changing trend from full-thickness keratoplasty to lamellar keratoplasty. There is rise in trend of lamellar keratoplasties over the period.

Twelve-Month Clinical and Histopathological Performance of a Novel Synthetic Cornea Device in Rabbit Model

Purpose

To report the biological stability and postoperative outcomes of a second-generation, single-piece, flexible synthetic cornea in a rabbit model.

Methods

Device materials and design were amended to enhance biointegration. Optic skirt design devices were made from compact perfluoroalkoxy alkane with porous expanded polytetrafluoroethylene ingrowth surface overlying the skirt and optic wall. Sixteen devices were implanted into intrastromal pocket in rabbit eyes. Rabbits were randomly assigned to 6- and 12-month follow-up cohorts (n = 8 in each) postoperatively. Monthly examinations and optical coherence tomography assessed cornea-device integration, iridocorneal angle, optic nerve, and retina.

Results

There were no intraoperative complications. All devices were in situ at exit, with clear optics. No retroprosthetic membrane, glaucoma, cataract formation, or retinal detachment was observed. Two rabbits in the 6-month group had mild, focal anterior lamella thinning without retraction adjacent to the optic near tight sutures. Three postoperative complications occurred in the 12-month group. One rabbit diagnosed with endophthalmitis was euthanized on day 228. Mild sterile focal retraction of anterior lamella occurred in two rabbits, which were terminated on days 225 and 315. Light microscopic examination of enucleated globes demonstrated fibroplasia with new collagen deposition into the porous scaffold without significant inflammation, encapsulation, or granuloma formation.

Conclusions

Clinical evaluations, imaging, and histopathological findings indicate favorable outcomes of this synthetic corneal device in a rabbit model. Early feasibility studies in humans are being planned.

Translational Relevance

Favorable 12-month results of the device in rabbits demonstrate vision-restoring potential in corneally blind individuals at high risk of failure with donor keratoplasty.

Trends in Keratoplasty Procedures During 2 Decades in a Major Tertiary Referral Center in Finland: 1995 to 2015

PURPOSE

The purpose of this study was to analyze trends in number, age-adjusted frequency, and type of keratoplasty in a major tertiary referral center, relative to patient and graft characteristics.

METHODS

A retrospective registry study of 1574 patients who in 1995 to 2015 underwent keratoplasty in the Helsinki University Eye Hospital (HUEH). Graft type and sequence, patient characteristics, and date of surgery were recorded. Main outcome measures were annual number, type, and age-adjusted frequency of keratoplasty; patient and graft characteristics; graft procurement; and national population-adjusted frequency of keratoplasty.

RESULTS

In HUEH, from 1995 to 2015, a total of 2191 keratoplasties were performed with 48% of the grafts procured intramurally; 76% were primary and 24% regrafts. The age-adjusted frequency of primary penetrating keratoplasty decreased by 52% from 0.96 to 0.46 per 100,000. The corresponding frequency of primary Descemet stripping automated endothelial keratoplasty increased by 367% from 0.3 to 1.4 after 2006, finally accounting for 68% of primary grafts. Men underwent primary penetrating keratoplasty (median 48 vs. 67 yrs, P = 0.0001) and anterior lamellar keratoplasty (median 37 vs. 46 yrs, P = 0.0015) at a younger age than women. Interval to the first regraft was comparable between sexes (median 2.2 vs. 1.9 yrs, respectively, P = 0.17). The national median population-adjusted frequency of keratoplasties was 3.2 per 100,000 from 2009 to 2015, and HUEH accounted for a median of 69% of them.

CONCLUSIONS

The increased frequency of keratoplasty in HUEH resulted from rapid adoption of Descemet stripping automated endothelial keratoplasty after 2006 and was facilitated by centralizing graft procurement to HUEH and the National Cell and Tissue Center Regea.

Clinical outcomes of Descemet membrane endothelial keratoplasty performed in eyes with keratoconus and corneal endothelial dysfunction

PURPOSE

To evaluate the clinical outcome of Descemet membrane endothelial keratoplasty (DMEK) performed in eyes with comorbid keratoconus (KCN) and corneal endothelial dysfunction.

METHODS

Twenty-five consecutive eyes of 14 patients with comorbid stable KCN underwent DMEK for corneal endothelial dysfunction; best spectacle corrected visual acuity (BSCVA), maximum corneal curvature (Kmax), maximum corneal power (Pmax), central corneal thickness (CCT), and intra- and postoperative complications were assessed.

RESULTS

Excluding eyes requiring re-transplantation for primary graft failure (n = 3), all eyes showed improvement in BSCVA, reaching ≥ 20/40 (0.5) in 86%, ≥ 20/25 (0.8) in 55%, and ≥ 20/20 (1.0) in 27% by one month postoperatively; 90%, 76%, and 48% by 6 months postoperatively; and 88%, 76%, and 47% by 12 months postoperatively. CCT decreased from 571μm preoperatively to 485μm at 1 month (p < 0.001) and 481μm at 12 months (p < 0.001). Kmax decreased by a median of 1.4 diopters (D) at 1 month (p = 0.003) and 3.1 D at 12 months (p = 0.021), and every eye with a preoperative Kmax ≥ 46 D demonstrated flattening. Pmax decreased by 2.1 D at 1 month (p = 0.001) and 4.0 D at 12 months (p = 0.016).

CONCLUSION

DMEK is technically feasible in eyes with comorbid KCN and may give excellent outcomes visual and refractive outcomes, including significant corneal flattening, which may potentially create a visually significant hyperopic shift in patients with severely ectatic corneas.

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.

Trends in Corneal Transplantation in a Tertiary Hospital in Brazil

PURPOSE

The purpose of this study was to analyze the evolving trends of surgical techniques and indications of corneal transplantation (CT) at a tertiary hospital in Brazil.

METHODS

The medical records of all patients who underwent CT at the Hospital Oftalmológico de Sorocaba (Sorocaba Eye Hospital) from the Banco de Olhos de Sorocaba (Sorocaba Eye Bank) group in Sorocaba, Brazil, from January 1, 2012, to December 31, 2019, were analyzed. Data regarding age, sex, transplant indication, and surgical technique were collected.

RESULTS

A total of 16,250 CTs were performed. There was a statistically significant decreasing trend of keratoconus-related CT ( P < 0.0001), with rates dropping from 41.7% among all CTs in 2012 to 25.5% in 2019. Penetrating keratoplasty, anterior lamellar keratoplasty, and endothelial keratoplasty (EK) accounted for 59.3%, 27.1%, and 7.8% of the CTs performed in 2012 and 33.3%, 16.4%, and 39.9% in 2019, respectively. A statistically significant decreasing trend was observed for penetrating keratoplasty ( P < 0.0001) and anterior lamellar keratoplasty ( P < 0.0001), whereas EK showed a statistically significant increasing trend during the period ( P < 0.0001). Among EKs, Descemet membrane EK increased statistically significantly from 12.8% in 2012 to 74.4% in 2019 ( P < 0.0001).

CONCLUSIONS

This study shows relevant evolving trends in indications and preferred CT techniques in a tertiary hospital in Brazil.

Changing Trends in Corneal Transplantation in Aotearoa/New Zealand, 1991 to 2020: Effects of Population Growth, Cataract Surgery, Endothelial Keratoplasty, and Corneal Cross-Linking for Keratoconus

PURPOSE

The purpose of this study was to identify trends in the primary indication for keratoplasty in New Zealand/Aotearoa (NZ) after significant population growth, increase in the number of cataract surgeries per population, widespread adoption of endothelial keratoplasty, and introduction of corneal cross-linking for keratoconus.

METHODS

Statistical analysis of the New Zealand National Eye Bank's prospective database of all keratoplasties was performed between January 1991 and January 2020. Indications for keratoplasty were isolated for the primary diagnosis.

RESULTS

In total, 6840 corneas were transplanted with mean 236 ± 57.5 transplants/year, increasing from 2.55 to 6.06 per 100,000 NZ population/year. Over the past decade, the number of transplant recipients aged 60 years or older has increased and recipients aged 20 to 39 years have plateaued. In 2019, for the first time, regraft became the most common indication (30.9%), followed by keratoconus (27.9%) and corneal dystrophy (18.8%), with a steady decline in bullous keratopathy. Proportions of the keratoplasty technique changed dramatically: penetrating keratoplasty fell from 91.4% in 2006 to 55.0% in 2019, Descemet's stripping endothelial keratoplasty increased from 0% to 29.5%, anterior lamellar keratoplasty increased from 2.5% to 5.7%, and Descemet membrane endothelial keratoplasty increased from 0% to 9.1%.

CONCLUSIONS

Keratoplasty trends in Aotearoa/NZ have changed considerably because of the evolution of phacoemulsification and keratoplasty techniques. Unlike proportions observed overseas, NZ still performs penetrating keratoplasties in over half of all transplants. Corneal cross-linking may be having an early effect of reducing keratoplasty rates for keratoconus.

Deep Anterior Lamellar Keratoplasty and Penetrating Keratoplasty for Keratoconus: A Claims-Based Analysis

PURPOSE

The purpose of this study was to report 1) demographic and clinical characteristics for US patients with keratoconus undergoing deep anterior lamellar keratoplasty (DALK) or penetrating keratoplasty (PK) and 2) complication rates for the 2 procedures.

METHODS

We performed a retrospective review of 2010 to 2018 health records for patients with keratoconus age younger than 65 years using the IBM MarketScan Database. A multivariable model adjusting for potential confounders was used to determine factors associated with receiving DALK over PK. Rates of complications 90 days and 1 year postoperatively were calculated. For select complications only (repeat keratoplasty, glaucoma surgery, and cataract surgery), Kaplan-Meier survival curves were additionally constructed over a period of up to 7 years.

RESULTS

A total of 1114 patients with keratoconus (mean age: 40.5 ± 12.6 years) were included in the analysis. Hundred nineteen received DALK, and 995 received PK. Regional differences exist, with patients in the north central United States having greater odds of receiving DALK than northeastern patients (OR = 5.08, 95% confidence interval, 2.37-10.90). Rates of endophthalmitis, choroidal hemorrhage, infectious keratitis, graft failure, graft rejection, postoperative cataract, glaucoma, or retinal surgery were all low at 90 days and 1 year. Complication rates for DALK and PK were both low beyond 1 year for repeat keratoplasty, cataract, and glaucoma surgery.

CONCLUSIONS

There are regional differences between DALK and PK utilization rates. In addition, DALK and PK complication rates in this nationally representative sample are low at 1 year and beyond, but further studies are needed to assess whether longer-term complications differ by procedure type.

Fuchs Endothelial Corneal Dystrophy associated risk variant, rs3768617 in LAMC1 shows allele specific binding of GFI1B

AIMS

To investigate the genetic and functional association of an intronic variant of LAMC1, rs3768617 with Fuchs endothelial corneal dystrophy (FECD) in the Indian population.

METHODS

Blood samples were collected from age and sex matched 356 controls and 120 FECD patients after a detailed assessment via specular microscopy. Genomic DNA was extracted and genotyping was done by fluorescence based capillary electrophoresis. The genetic association of rs3768617 polymorphisms was computed by the chi-square (χ²) test. Bioinformatics studies were performed to find the allele specific binding of different transcription factors in the region of rs3768617 and functional evaluation assessed by luciferase assay followed by Electrophoretic Mobility Shift Assay (EMSA) and Chromatin Immunoprecipitation assay (ChIP). Immunofluorescence assay was carried out to check for any differential expression of GFI1B between control and FECD endothelium samples.

RESULTS

SNP rs3768617 {chr1:183123365 (GRCh38.p13)} was found to be genetically associated with FECD in Indian population (p = 2.646 × 10^-8). Luciferase assay suggested that the rs3768617 locus has a regulatory role. In silico analysis showed that the transcription factor, GFI1B binds to the risk allele 'G' of rs3768617, but not to the protective allele 'A' which was also experimentally validated by EMSA. High enrichment of DNA flanking the surrounding region of rs3768617 was also found in presence of GFI1B specific antibody in ChIP assay. There was a 0.63 fold decrease in GFI1B expression in FECD affected corneal endothelium compared to control endothelium.

CONCLUSIONS

The genetic association of rs3768617 in LAMC1 with FECD pathogenesis is mediated by GFI1B, thus finding the functional role of LAMC1 in FECD pathogenesis.

Demographic profile and clinical course of Fuchs endothelial corneal dystrophy in Mexican patients

PURPOSE

To describe the demographic characteristics and clinical course of Fuchs endothelial corneal dystrophy (FECD) in a Mexican-mestizo population.

METHODS

A retrospective observational and longitudinal study was performed in consecutive patients with the clinical diagnosis of Fuchs endothelial corneal dystrophy seen at our institution. Initial and last follow-up best-corrected visual acuity, slit-lamp findings, and specular microscopy endothelial morphometric parameters were analyzed.

RESULTS

One hundred and two eyes belonging to 51 patients were included in the analysis. Median age at the time of diagnosis was 69 years (range, 25-87 years) with a female-to-male ratio of 3.3:1. Visual loss (40%) followed by glare (13.3%) and fluctuating matutine vision loss (13.3%) was the most common complaints at presentation. Regarding FECD staging, 65 (63.7%) were classified as stage-I FECD, 21 (20.6%) stage-II, and 15 (14.7%) as stage-III. A high percentage of eyes (44.1%) presented visual impairment ( ≤ 20/50) at presentation, and the presence of isolated corneal guttata was the most common stage of presentation (64%) at slit-lamp examination. While fifty-nine (57.8%) eyes did not require any medical or surgical management, 17 (16.7%) eyes were managed with hypertonic saline eyedrops alone or in combination with bandage contact lens, and 18 (17.6%) required corneal transplantation. Penetrating keratoplasty alone (8 eyes, 44.4%), or in combination with cataract extraction and intraocular lens implantation (3 eyes, 16.7%), was the most frequent surgical technique performed.

CONCLUSION

Demographical characteristics of Fuchs dystrophy regarding age at presentation, gender distribution, and clinical stage at the time of diagnosis did not differ significantly from other international reports. Almost 20% of these patients will require keratoplasty during the disease, emphasizing the need for safer and more reproducible keratoplasty techniques.

Trends in surgical procedures and indications for corneal transplantation over 27 years in a tertiary hospital in Japan

PURPOSE

To characterize trends in procedures, and indications for corneal transplantation over 27 years in a single referral center in Japan.

STUDY DESIGN

Retrospective study.

METHODS

Data from a consecutive series of corneal transplant surgery cases performed from 1991 to 2017at Ichikawa General Hospital were collected. The surgical procedures, indications, and causes of corneal endothelial dysfunction were evaluated.

RESULTS

Among 6,025 transplantations, a total of 3,991 cases underwent penetrating keratoplasty (PKP), 1009 underwent (deep) anterior lamellar keratoplasty, 746 underwent endothelial keratoplasty, and 309 underwent epithelial transplantation. Over that period the frequency of PKP decreased, whereas the frequency of lamellar keratoplasty increased. The four major surgical indications were bullous keratoplasty (BK 30.0%), regraft (24.2%), post-keratitis scars (17.1%), and keratoconus (11.4%). After dividing the study period into four time periods, we found that BK and regraft increased (from 20.3% to 34.5% and 18.2% to 31.1%, respectively), whereas post-keratitis scars and keratoconus decreased (from 26.0% to 9.5% and 14.1% to 7.2%, respectively) between the first and last period. Pseudophakic or aphakic BK were the major causes of corneal endothelial dysfunction until 2010. Cases of laser-iridotomy-induced BK peaked in 35 eyes (34.3% of BK) in 2000 and declined after 2013. Cases of Fuchs endothelial corneal dystrophy increased from 0 in 1991, to 15 eyes (18.5% of BK) in 2017.

CONCLUSION

Lamellar keratoplasty has replaced PKP in our hospital. BK and regraft have increased, whereas post-keratitis scars and keratoconus have decreased. Laser-iridotomy-induced BK has decreased during the past decade, whereas Fuchs endothelial corneal dystrophy has increased.

Intraoperative optical coherence tomography guided corneal sweeping for removal of remnant Interface fluid during ultra-thin Descemet stripping automated endothelial keratoplasty

BACKGROUND

Remnant interface fluid following Descemet stripping automated endothelial keratoplasty (DSAEK) is associated with postoperative detachments. The aim of this study was to assess outcomes of intraoperative optical coherence tomography (iOCT) guided meticulous peripheral corneal sweeping for removal of interface fluid during ultra-thin (UT) DSAEK.

METHODS

This retrospective study included all eyes underwent iOCT guided UT-DSAEK from October 2016 to February 2018 at the Hanusch Hospital, Vienna, Austria. Peripheral meticulous corneal sweeping was performed to remove excess fluid. Central graft thickness (CGT) was measured prior to surgery, after graft bubbling and after corneal sweeping. Remnant interface fluid rates were compared between eyes that underwent rebubbling and those that did not.

RESULTS

Overall, 28 eyes of 28 patients with a mean age of 73.9 ± 10.0 years were included. An iOCT guided meticulous peripheral sweeping was performed in 89.3% (n = 25) of the cases. Following 84% (n = 21) of the peripheral sweeping performed, remnant fluid was no longer identified. Following peripheral sweeping the interface fluid height was reduced from 17.31 ± 15.96 μm to 3.46 ± 9.52 μm (p < 0.001) and CGT was reduced by 7% (p < 0.001). Rebubbling was performed in 17.9% (n = 5) of the cases. The rebubbling group had a greater proportion of patients that had remnant fluid identified with iOCT at the end of surgery despite meticulous peripheral sweeping (60.0% versus 4.4%, p = 0.01).

CONCLUSION

The iOCT identified subclinical remnant fluid in nearly 90% of UT-DSAEK cases. An iOCT guided peripheral corneal sweeping led to resolution of interface fluid in a majority of cases. Eyes with persistent remnant fluid despite peripheral corneal sweeping are more likely to require subsequent rebubbling.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Fuchs endothelial corneal dystrophy: The vicious cycle of Fuchs pathogenesis

Fuchs endothelial corneal dystrophy (FECD) is the most common primary corneal endothelial dystrophy and the leading indication for corneal transplantation worldwide. FECD is characterized by the progressive decline of corneal endothelial cells (CECs) and the formation of extracellular matrix (ECM) excrescences in Descemet's membrane (DM), called guttae, that lead to corneal edema and loss of vision. FECD typically manifests in the fifth decades of life and has a greater incidence in women. FECD is a complex and heterogeneous genetic disease where interaction between genetic and environmental factors results in cellular apoptosis and aberrant ECM deposition. In this review, we will discuss a complex interplay of genetic, epigenetic, and exogenous factors in inciting oxidative stress, auto(mito)phagy, unfolded protein response, and mitochondrial dysfunction during CEC degeneration. Specifically, we explore the factors that influence cellular fate to undergo apoptosis, senescence, and endothelial-to-mesenchymal transition. These findings will highlight the importance of abnormal CEC-DM interactions in triggering the vicious cycle of FECD pathogenesis. We will also review clinical characteristics, diagnostic tools, and current medical and surgical management options for FECD patients. These new paradigms in FECD pathogenesis present an opportunity to develop novel therapeutics for the treatment of FECD.

Refractive Outcomes of Descemet Membrane Endothelial Keratoplasty Combined With Cataract Surgery in Fuchs Endothelial Dystrophy

PURPOSE

To evaluate the refractive outcomes of Descemet membrane endothelial keratoplasty combined with cataract surgery (DMEK triple) in patients with Fuchs endothelial dystrophy.

METHODS

A retrospective analysis of 68 eyes of 68 patients with Fuchs endothelial dystrophy who underwent DMEK triple between 2014 and 2018.

RESULTS

The mean age of patients was 66.5 ± 8.6 years, and 65% (44 of 68) were female. Mean target refraction was -0.69 diopters (D) (interquartile range: -0.80 to -0.50 D). At 6 months, 47% (32 of 68) and 63% (43 of 68) of eyes were within ±0.50 and ±1.00 D of target refraction, respectively. Among eyes greater than 0.50 D from target, 78% (28 of 36) were hyperopic surprises. Mean spherical equivalent at 6 months was -0.14 ± 1.26 D, representing a mean hyperopic shift of 0.55 D from target. Preoperative pachymetry was higher in eyes with greater than 0.50 D of hyperopic surprise (648 ± 60 vs 613 ± 49 µm, P = .04). Refractive shift was greater in eyes with a preoperative central corneal thickness of 640 µm or greater versus eyes with a central corneal thickness of less than 640 µm (+1.20 ± 0.92 vs +0.40 ± 0.99 D, P = .02). None of the eyes with a preoperative central corneal thickness of 640 µm or greater shifted myopically compared to target (range: -0.09 to +2.89 D).

CONCLUSIONS

A mean hyperopic shift of 0.55 D from target refraction occurred after DMEK triple, and 47% of eyes were within 0.50 D of target refraction at 6 months postoperatively. Thicker corneas preoperatively had greater hyperopic shift. A greater myopic target refraction may be warranted in eyes with a preoperative central corneal thickness of 640 µm or greater. [J Refract Surg. 2020;36(10):661-666.].

Corneal endothelial dysfunction: Evolving understanding and treatment options

The cornea is exquisitely designed to protect the eye while transmitting and focusing incoming light. Precise control of corneal hydration by the endothelial cell layer that lines the inner surface of the cornea is required for optimal transparency, and endothelial dysfunction or damage can result in corneal edema and visual impairment. Advances in corneal transplantation now allow selective replacement of dysfunctional corneal endothelium, providing rapid visual rehabilitation. A series of technique improvements have minimized complications and various adaptations allow use even in eyes with complicated anatomy. While selective endothelial keratoplasty sets a very high standard for safety and efficacy, a shortage of donor corneas in many parts of the world restricts access, prompting a search for alternatives. Clinical trials are underway to evaluate the potential for self-recovery after removal of dysfunctional central endothelium in patients with healthy peripheral endothelium. Various approaches to using cultured human corneal endothelial cells are also in clinical trials; these aim to multiply cells from a single donor cornea for use in potentially hundreds of patients. Pre-clinical studies are underway with induced pluripotent stem cells, endothelial stem cell regeneration, gene therapy, anti-sense oligonucleotides, and various biologic/pharmacologic approaches designed to treat, prevent, or retard corneal endothelial dysfunction. The availability of more therapeutic options will hopefully expand access around the world while also allowing treatment to be more precisely tailored to each individual patient.

Incidence and Outcomes of Cystoid Macular Edema after Descemet Membrane Endothelial Keratoplasty (DMEK) and DMEK Combined with Cataract Surgery

PURPOSE

To investigate the incidence and outcomes of cystoid macular edema (CME) after Descemet membrane endothelial keratoplasty (DMEK) alone and DMEK combined with cataract surgery (DMEK triple).

MATERIALS AND METHODS

A retrospective chart review was performed for patients who underwent DMEK and DMEK triple between January 2014 and March 2018 at two tertiary hospitals. Patients with minimum of 6 months of follow-up were included. Logistic regression analysis was used to identify potential risk factors for CME including gender, age, glaucoma, uveitis, epiretinal membrane, diabetes mellitus, iridotomy, and rebubbling.

RESULTS

09 eyes of 193 patients who underwent DMEK (124 eyes) and DMEK triple (85 eyes) were included. The 6-month incidence of CME was 3.8% (8/209) for all cases, 2.4% (2/85) for DMEK triple, and 4.8% (6/124) for DMEK alone. CME was treated with topical prednisolone acetate 1% and nepafenac four times daily, and/or periocular triamcinolone acetonide, with resolution in all cases. On average, CME was detected 8.9 ± 2.1 weeks postoperatively, with a mean time to resolution of 4.1 ± 1.7 months. The 6-month best-corrected distance visual acuity of eyes that developed CME was not significantly different compared to eyes that did not develop CME (0.17 ± 0.15 logMAR vs. 0.23 ± 0.27 logMAR; p = .76). On logistic regression analysis, no risk factors for developing CME were identified.

CONCLUSIONS

The incidence of CME after DMEK was low and not associated with decreased long-term visual acuity. Most cases of CME occurred between 1 and 3 months postoperatively. Predictive factors for CME after DMEK require further study.

DMEK in Super-Seniors: Clinical Outcomes of Descemet Membrane Endothelial Keratoplasty Performed in Patients ≥ 90 Years Old

PURPOSE/AIMS OF THE STUDY

To evaluate the clinical outcomes of Descemet membrane endothelial keratoplasty (DMEK) performed in the "oldest old" patients, i.e. ≥ 90 years.

MATERIALS AND METHODS

Between the years of 2009 and 2019, 20 consecutive eyes of 17 patients aged ≥ 90 underwent DMEK for endothelial dysfunction. Best corrected visual acuity (BCVA), central corneal thickness (CCT), endothelial cell density (ECD), graft survival, and intra- and postoperative complications were assessed.

RESULTS

Except in one case in which the DMEK surgery could not be completed, all operated eyes experienced an improvement in BCVA, although only 50% achieved ≥ 20/40 (0.5) by 1 year postoperatively. One year after surgery, median CCT had declined from 641(±161) μm to 480 (±34) μm, and median endothelial cell density was reduced by 53%, from 2574 (±286) to 1226 (±404) cells/mm². Six of 19 eyes receiving DMEK grafts (32%) developed partial graft detachments requiring re-bubbling. One eye experienced a secondary graft failure at 6 months and underwent repeat endothelial keratoplasty.

CONCLUSION

DMEK is technically feasible in the oldest old patients and may yield significant visual improvements, although an elevated risk of some postoperative complications including graft detachment with corresponding need for re-bubbling may be anticipated.

Loss of NQO1 generates genotoxic estrogen-DNA adducts in Fuchs Endothelial Corneal Dystrophy

Fuchs Endothelial Corneal Dystrophy (FECD) is an age-related genetically complex disease characterized by increased oxidative DNA damage and progressive degeneration of corneal endothelial cells (HCEnCs). FECD has a greater incidence and advanced phenotype in women, suggesting a possible role of hormones in the sex-driven differences seen in the disease pathogenesis. In this study, catechol estrogen (4-OHE2), the byproduct of estrogen metabolism, induced genotoxic estrogen-DNA adducts formation, macromolecular DNA damage, and apoptotic cell death in HCEnCs; these findings were potentiated by menadione (MN)-mediated reactive oxygen species (ROS). Expression of NQO1, a key enzyme that neutralizes reactive estrogen metabolites, was downregulated in FECD, indicating HCEnC susceptibility to reactive estrogen metabolism in FECD. NQO1 deficiency in vitro exacerbated the estrogen-DNA adduct formation and loss of cell viability, which was rescued by the supplementation of N-acetylcysteine, a ROS scavenger. Notably, overexpression of NQO1 in HCEnCs treated with MN and 4-OHE2 quenched the ROS formation, thereby reducing the DNA damage and endothelial cell loss. This study signifies a pivotal role for NQO1 in mitigating the macromolecular oxidative DNA damage arising from the interplay between intracellular ROS and impaired endogenous estrogen metabolism in post-mitotic ocular tissue cells. A dysfunctional Nrf2-NQO1 axis in FECD renders HCEnCs susceptible to catechol estrogens and estrogen-DNA adducts formation. This novel study highlights the potential role of NQO1-mediated estrogen metabolite genotoxicity in explaining the higher incidence of FECD in females.

"Double-Bubble" Descemet Membrane Endothelial Keratoplasty Unfolding in Eyes With Deep Anterior Chambers and Anterior Chamber Intraocular Lenses

PURPOSE

To describe a standardized technique for Descemet membrane endothelial keratoplasty unfolding in eyes with deep anterior chambers and anterior chamber intraocular lenses (ACIOLs).

METHODS

Two air bubbles are used simultaneously: the first placed on top of the graft and the second one underneath.

RESULTS

The 2 bubbles work in concert-the bubble on top props the tissue partially open, while the bubble underneath levitates the graft away from the ACIOL and provides support for subsequent unfolding maneuvers.

CONCLUSIONS

By sandwiching the graft between 2 bubbles, unfolding may proceed away from physical contact with the ACIOL, even in eyes with hyper-deep chambers.

Literature review and suggested protocol for prevention and treatment of corneal graft rejection

Effective prophylaxis and treatment of corneal graft rejection are essential to improve outcomes in corneal transplantation. To date, there has been no standardized protocol published that outlines the optimal prophylactic and therapeutic approaches and, furthermore, the published controlled trials on this subject are limited. Likewise, no study has addressed how the level of antigen exposure varies between different types of keratoplasties. The aim of this paper is to provide a simple evidence-based protocol for the prevention and treatment of corneal graft rejection.

Lymphatic vessels identified in failed corneal transplants with neovascularisation

BACKGROUND

Corneal transplant failure with neovascularisation is a leading indication for full-thickness grafts in patients. Lymphangiogenesis is implicated in the pathology of graft failure, and here we systematically evaluate failed human corneal transplants with neovascularisation for the presence of lymphatic vessels.

METHODS

Nine failed grafts with neovascularisation, based on H&E staining with subsequent immunoperoxidase staining for CD31, a blood vessel marker, were selected. Lymphatics were investigated by immunohistochemical and immunofluorescence approaches using podoplanin as a lymphatic marker. In two of nine cases, fluorescence in situ hybridisation (FISH) was used for detection of lymphatic mRNAs including podoplanin, VEGFR-3 and LYVE-1. All immunofluorescence and FISH samples were compared with positive and negative controls and visualised by confocal microscopy.

RESULTS

Corneal neovascularisation was established in all cases by H&E and further confirmed by CD31 immunoreactive profiles. Immunohistochemistry for the podoplanin antibody was positive in all cases and showed morphologies ranging from distinct luminal structures to elongated profiles. Simultaneous immunofluorescence using CD31 and podoplanin showed lymphatic vessels distinct from blood vessels. Podoplanin immunofluorescence was noted in seven of nine cases and revealed clear lumina of varying sizes, in addition to lumen-like and elongated profiles. The presence of lymphatic mRNA was confirmed by FISH studies using a combination of at least two of podoplanin, VEGFR-3 and LYVE-1 mRNAs.

CONCLUSIONS

The consistent finding of lymphatic vessels in failed grafts with neovascularisation implicates them in the pathogenesis of corneal transplant failure, and points to the lymphatics as a potential new therapeutic target.