Structure and properties of the acellular porcine cornea irradiated with 60Co-γ and electron beam and its histocompatibility

Acellular porcine cornea (APC) has been used in corneal transplantation and treatment of the corneal diseases. Sterilization is a key step before the application of graft, and irradiation is one of the most commonly used methods. In this paper, APC was prepared by the physical freeze-thawing combined with biological enzymes, and the effects of the electron beam (E-beam) and cobalt 60 (60Co-γ) at the dose of 15 kGy on the physicochemical properties, structure, immunogenicity, and biocompatibility of the APC were investigated. After decellularization, the residual DNA was 20.86 ± 1.02 ng/mg, and the α-Gal clearance rate was more than 99%. Irradiation, especially the 60Co-γ, reduced the cornea's transmittance, elastic modulus, enzymatic hydrolysis rate, swelling ratio, and cross-linking degree. Meanwhile, the diameter and spacing of the collagen fibers increased. In the rat subcutaneous implantation, many inflammatory cells appeared in the unirradiated APC, while the irradiated had good histocompatibility, but the degradation was faster. The lamellar keratoplasty in rabbits indicated that compared to the E-beam, the 60Co-γ damaged the chemical bond of collagen to a larger extent, reduced the content of GAGs, and prolonged the complete epithelization of the grafts. The corneal edema was more serious within 1 month after the surgery. After 2 months, the thickness of the APC with the two irradiation methods tended to be stable, but that in the 60Co-γ group became thinner. The pathological results showed that the collagen structure was looser and the pores were larger, indicating the 60Co-γ had a more extensive effect on the APC than the E-beam at 15 kGy.

Cost-effectiveness of the ADVISE trial: An intraoperative OCT protocol in DMEK surgery

The intraoperative optical coherence tomography (iOCT) is recently introduced in Descemet membrane endothelial keratoplasty (DMEK) surgery, which aims to increase clinical performance and surgery safety. However, the acquisition of this modality is a substantial investment. The objective of this paper is to report on the cost-effectiveness of an iOCT-protocol in DMEK surgery with the Advanced Visualization in Corneal Surgery Evaluation (ADVISE) trial. This cost-effectiveness analysis uses data 6 months postoperatively from the multicentre prospective randomized clinical ADVISE trial. Sixty-five patients were randomized to usual care (n = 33) or the iOCT-protocol (n = 32). Quality-Adjusted Life Years (EQ-5D-5L), Vision-related Quality of Life (NEI-VFQ-25) and self-administered resources questionnaires were administered. Main outcome is the incremental cost-effectiveness ratio (ICER) and sensitivity analyses. The iOCT protocol reports no statistical difference in ICER. For the usual care group compared with the iOCT protocol, respectively, the mean societal costs are €5027 compared with €4920 (Δ€107). The sensitivity analyses report the highest variability on time variables. This economic evaluation learned that there is no added value in quality of life or cost-effectiveness in using the iOCT protocol in DMEK surgery. The variability of cost variables depends on the characteristics of an eye clinic. The added value of iOCT could gain incrementally by increasing surgical efficiency, and aiding in surgical decision-making.

Corneal blindness in the developing world: The role of prevention strategies

Corneal blindness is an important contributor to the burden of global blindness and has a greater prevalence in low-income countries of the developing world where resources and infrastructure are limited. The causes of corneal blindness too are different from high-income countries and include infectious keratitis, ocular trauma, and xerophthalmia. Persons with these indications tend to have unfavourable outcomes after corneal transplantation, limiting their chances of benefitting from this sight-saving procedure. However, most causes of corneal blindness in the developing world are preventable. This highlights the importance of understanding the unique challenges in these regions and the need for targeted interventions. This article discusses various prevention strategies, including primordial, primary, and secondary prevention, aimed at reducing the burden of corneal blindness in low-income countries. These include capacity building, training, and awareness campaigns to reduce the risk factors of ocular trauma, infectious keratitis, and to improve access to first aid. It is also important to promote safe eye practices and tackle nutritional deficiencies through public health interventions and policy changes. Providing the required training to general ophthalmologists in the management of basic corneal surgeries and diseases and enhancing the accessibility of eye care services in rural areas will ensure early treatment and prevent sequelae. Current treatment modalities belong to the tertiary level of prevention and are largely limited to corneal transplantation. In developing nations, there is a scarcity of donor corneal tissue necessitating an urgent expansion of eye banking services. Alternative approaches to corneal transplantation such as 3D printed corneas, cultured stem cells, and biomaterials should also be explored to meet this demand. Thus, there is a need for collaborative efforts between healthcare professionals, policymakers, and communities to implement effective prevention strategies and reduce the prevalence of corneal blindness in the developing world.

Towards Precision Ophthalmology: The Role of 3D Printing and Bioprinting in Oculoplastic Surgery, Retinal, Corneal, and Glaucoma Treatment

In the forefront of ophthalmic innovation, biomimetic 3D printing and bioprinting technologies are redefining patient-specific therapeutic strategies. This critical review systematically evaluates their application spectrum, spanning oculoplastic reconstruction, retinal tissue engineering, corneal transplantation, and targeted glaucoma treatments. It highlights the intricacies of these technologies, including the fundamental principles, advanced materials, and bioinks that facilitate the replication of ocular tissue architecture. The synthesis of primary studies from 2014 to 2023 provides a rigorous analysis of their evolution and current clinical implications. This review is unique in its holistic approach, juxtaposing the scientific underpinnings with clinical realities, thereby delineating the advantages over conventional modalities, and identifying translational barriers. It elucidates persistent knowledge deficits and outlines future research directions. It ultimately accentuates the imperative for multidisciplinary collaboration to enhance the clinical integration of these biotechnologies, culminating in a paradigm shift towards individualized ophthalmic care.

The Role of Rho Kinase Inhibitors in Corneal Diseases

The cornea, as the outermost layer of the eye, plays a crucial role in vision by focusing light onto the retina. Various diseases and injuries can compromise its clarity, leading to impaired vision. This review aims to provide a thorough overview of the pharmacological properties, therapeutic potential and associated risks of Rho-associated protein kinase (ROCK) inhibitors in the management of corneal diseases. The article focuses on four key ROCK inhibitors: Y-27632, fasudil, ripasudil, and netarsudil, providing a comparative examination. Studies supporting the use of ROCK inhibitors highlight their efficacy across diverse corneal conditions. In Fuchs' endothelial corneal dystrophy, studies on the application of Y-27632, ripasudil, and netarsudil demonstrated noteworthy enhancements in corneal clarity, endothelial cell density, and visual acuity. In pseudophakic bullous keratopathy, the injection of Y-27632 together with cultured corneal endothelial cells into the anterior chamber lead to enhanced corneal endothelial cell density and improved visual acuity. Animal models simulating chemical injury to the cornea showed a reduction of neovascularization and epithelial defects after application of fasudil and in a case of iridocorneal endothelial syndrome netarsudil improved corneal edema. Addressing safety considerations, netarsudil and ripasudil, both clinically approved, exhibit adverse events such as conjunctival hyperemia, conjunctival hemorrhage, cornea verticillata, conjunctivitis, and blepharitis. Monitoring patients during treatment becomes crucial to balancing the potential therapeutic benefits with these associated risks. In conclusion, ROCK inhibitors, particularly netarsudil and ripasudil, offer promise in managing corneal diseases. The comparative analysis of their pharmacological properties and studies supporting their efficacy underscore their potential therapeutic significance. However, ongoing research is paramount to comprehensively understand their safety profiles and long-term outcomes in diverse corneal conditions, guiding their optimal application in clinical practice.

Effector T Cells Promote Fibrosis in Corneal Transplantation Failure

Purpose

To evaluate whether fibrosis contributes to corneal transplant failure and to determine whether effector CD4+ T cells, the key immune cells in corneal transplant rejection, play a direct role in fibrosis formation.

Methods

Allogeneic corneal transplantation was performed in mice. Graft opacity was evaluated by slit-lamp biomicroscopy, and fibrosis was assessed by in vivo confocal microscopy. Expression of alpha-smooth muscle actin (α-SMA) in both accepted and failed grafts was assessed by real-time PCR and immunohistochemistry. Frequencies of graft-infiltrating CD4+ T cells, neutrophils, and macrophages were assessed using flow cytometry. In vitro, MK/T-1 corneal fibroblasts were co-cultured with activated CD4+CD25- effector T cells isolated from corneal transplant recipient mice, and α-SMA expression was quantified by real-time PCR and ELISA. Neutralizing antibody was used to evaluate the role of interferon gamma (IFN-γ) in promoting α-SMA expression.

Results

The majority of failed grafts demonstrated clinical signs of fibrosis which became most evident at week 6 after corneal transplantation. Failed grafts showed higher expression of α-SMA as compared to accepted grafts. Flow cytometry analysis showed a significant increase in CD4+ T cells in failed grafts compared to accepted grafts. Co-culture of activated CD4+CD25- effector T cells with corneal fibroblasts led to an increase in α-SMA expression by fibroblasts. Inhibition of IFN-γ in culture significantly suppressed this increase in α-SMA expression as compared to immunoglobulin G control.

Conclusions

Fibrosis contributes to graft opacity in corneal transplant failure and is mediated at least in part by effector CD4+ T cells via IFN-γ.

Customized therapeutic deep anterior lamellar keratoplasty in perforated Mooren's ulcer: A novel technique

We describe customized therapeutic deep anterior lamellar keratoplasty (DALK) for treating a perforated Mooren's ulcer. Slit-lamp biomicroscopy revealed corneal perforation (3.5 mm × 3.0 mm) with iris prolapse. The corneal melt extended from 9.0 o'clock to 4.0 o'clock. The peripheral edge of the ulcer was sloping, whereas the medial edge showed undermining. Immunological tests did not reveal any evidence of systemic autoimmune disease. In view of extensive peripheral corneal melt with large corneal perforation, the patient needed tectonic keratoplasty. The penetrating graft is not only technically demanding but also results in a poor visual outcome. We advised customized tectonic DALK. We used two different-sized trephines to obtain appropriate-sized donor tissue and avoided manual dissection. The post-surgery period was uneventful. He was prescribed topical steroids and oral methotrexate. He achieved 6/9 aided visual acuity at 4 months and maintained it until the last follow-up at 36 months.

[Outcomes of hemi-Descemet membrane endothelial keratoplasty and phacoemulsification for the treatment of primary Fuchs' endothelial corneal dystrophy combined with cataract]

PURPOSE

This study evaluates the long-term results of surgical treatment of patients with Fuchs' endothelial corneal dystrophy and cataract.

MATERIAL AND METHODS

The study included 24 patients (24 eyes) with primary Fuchs' endothelial corneal dystrophy and cataract, who underwent cataract phacoemulsification with IOL implantation and of Descemet's membrane endothelial keratoplasty with a semicircular graft (hemi-DMEK). The effect of treatment was assessed by best corrected visual acuity (BCVA), central corneal thickness (CCT) and endothelial cell density (ECD).

RESULTS

In total, surgical treatment involved 14 donor corneas that were divided in half during the preparation and isolation of the Descemet's membrane (DM). By month 12 after the surgery an increase in visual functions and graft transparency were observed in 23 patients (23 eyes) out of 24. Repeated keratoplasty was required in one case due to fibrosis of the posterior layers of recipient's corneal stroma. At 12 months postoperatively, the study group showed an increase in BCVA from 0.16±0.1 to 0.75±20, a decrease in CCT from 650.9±4.5 μm to 519.6±43.9, and a decreased in ECD from 2850.5±84.7 cells/mm2 up to 1285.5±277.2 cells/mm2. Thus, the loss of endothelial cells at one year after surgery amounted to 54.9%.

CONCLUSIONS

The developed method for transplantation of a semicircular DM fragment provides a tissue-saving approach to endothelial keratoplasty, and considering the high percentage of transparent engraftment of grafts and complete visual rehabilitation, it can be recommended in the treatment of patients with cataract and Fuchs' endothelial corneal dystrophy.

Impact of cleanroom status on the reasons for discarding organ-cultured corneal transplants in a modern eye bank - More donor corneas thanks to astronaut suit?

PURPOSE

This study investigated the influence of cleanroom conditions on the discard rates of donor corneas in a German university eye bank.

METHODS

Discard rates were analysed from 2017 to 2020 at the LIONS Cornea Bank at Saarland University Medical Center. 1941 corneas from 971 donors were included. 1262 corneas (65.1%) were stored in a class D cleanroom from 2017 to 2019 and processed in a cleanroom class A sterile bank (group 1). 679 corneas (34.9%) were continuously stored in a class B cleanroom and processed in a class A cleanroom safety cabinet in the same room from 2019 to 2020 (group 2). The target parameter of this work was the number of contamination-related discards. Although they cannot be influenced by the spatial conditions, the discards due to insufficient endothelial quality, serology, contraindications, scars and technical causes were also recorded. Statistical analysis was performed using SPSS and various testing procedures.

RESULTS

In group 1, significantly more corneas were discarded due to positive serology (6.9%|3.8%, p = 0.020). There was no significant change between both groups for either contamination or the other reasons for discard.

CONCLUSION

Optimization of hygiene standards from cleanroom class D to B did not reduce contamination. Serology, endothelial quality, medical contraindications and the presence of scars cannot be influenced by cleanroom conditions.

A Versatile Hydrogel with Antibacterial and Sequential Drug-Releasing Capability for the Programmable Healing of Infectious Keratitis

Hydrogels have attracted tremendous attention as favorable corneal substitutes for treating severe infectious keratitis (IK). However, current hydrogel-based corneal substitutes were majorly designed to promote the single stage of corneal regeneration, which falls short in meeting the clinical management needs of severe IK including the multiple phases of corneal wound healing. Herein, we introduce a versatile hybrid hydrogel (SQPV) composed of silk fibroin and chitosan, which exhibits spatiotemporal properties for drug release. The SQPV is fabricated by incorporating verteporfin-loaded poly(lactic-co-glycolic)-polyethylene glycol-o-nitrobenzene micelles into a hydrogel network, which is formed from methacrylate silk fibroin and glycidyl methacrylate functionalized quaternized chitosan containing polydeoxyribonucleotide. This double network approach results in a material with exceptional anti-inflammatory, antibacterial, and proliferative stimulation and tissue remodeling regulation capabilities. Furthermore, SQPV showcases mechanical strength and transparency akin to those of native cornea. Extensive in vitro and in vivo studies validate SQPV's ability to effectively eliminate residual bacteria, mitigate inflammation, foster regeneration of corneal epithelium and stroma, prevent corneal scarring, and ultimately expedite wound healing. In summary, the SF/CS-based hybrid hydrogel may represent a promising substitute for comprehensive corneal repair and regeneration in severe IK.

Comparative Proteomics Reveals Prolonged Corneal Preservation Impaired Ocular Surface Immunity Accompanied by Fibrosis in Human Stroma

Cornea transplantation is one of the most commonly performed allotransplantations worldwide. Prolonged storage of donor corneas leads to decreased endothelial cell viability, severe stromal edema, and opacification, significantly compromising the success rate of corneal transplantation. Corneal stroma, which constitutes the majority of the cornea, plays a crucial role in maintaining its shape and transparency. In this study, we conducted proteomic analysis of corneal stroma preserved in Optisol-GS medium at 4 °C for 7 or 14 days to investigate molecular changes during storage. Among 1923 identified proteins, 1634 were quantifiable and 387 were significantly regulated with longer preservation. Compared to stroma preserved for 7 days, proteins involved in ocular surface immunomodulation were largely downregulated while proteins associated with extracellular matrix reorganization and fibrosis were upregulated in those preserved for 14 days. The increase in extracellular matrix structural proteins together with upregulation of growth factor signaling implies the occurrence of stromal fibrosis, which may compromise tissue clarity and cause vision impairments. This study is the first to provide insights into how storage duration affects corneal stroma from a proteomic perspective. Our findings may contribute to future research efforts aimed at developing long-term preservation techniques and improving the quality of preserved corneas, thus maximizing their clinical application.

A study on knowledge, attitude, and practice about eye donation among medical students and healthcare professionals at a tertiary hospital in Eastern India

Purpose

To assess and analyze the rate of knowledge, attitude, and practice patterns about eye donation among medical and healthcare professionals in a tertiary care hospital in eastern India.

Methods

This was a cross-sectional, descriptive study conducted on medical students, resident doctors, and nursing and paramedical staff at a tertiary institute in the year 2020. A pretested, structured questionnaire consisting of 28 questions in the three subsections based on knowledge and awareness, attitudes and beliefs, and practice patterns mainly willingness to donate eyes by pledging, was noted. All the responses were individually scored, and the total scores were calculated. Univariate analysis was done to find out the factors that had a positive or negative influence on the knowledge and willingness about eye donation.

Results

Around 270 participants responded to this survey. The majority of the respondents (206, 76.3%) were below 30 years and 64.4% were males. Awareness about eye donation was 95.6% but a willingness to pledge was observed in 51.5% of participants. The total practice score was lower among nonmedicos compared with medicos (3.33 ± 1.22 vs 3.74 ± 0.64), (P < 0.001). On univariate analysis, the Crude Odds Ratio with a 95% confidence interval was 25.787 (5.18-128.33) in the occupational category (P < 0.001).

Conclusion

The study reported an adequate knowledge level among doctors and healthcare workers. The practice pattern among the nursing staff and paramedical workers needs to be improved as they can play a pivotal role in strengthening the hospital corneal retrieval program. They can also be the key messengers during public awareness campaigns for eye donations in our country.

Corneal Transplantation for Infectious Keratitis: A Prospective Dutch Registry Study

PURPOSE

The aim of this study was to analyze real-world practice patterns and graft survival after corneal transplantation for infectious keratitis in the Netherlands.

METHODS

All consecutive keratoplasties for infectious keratitis registered in the Netherlands Organ Transplant Registry were included. Graft survival was analyzed using Kaplan-Meier survival curves with Cox regression to compare the 3 most common pathogens with subgroup analysis for type and reason of transplantation, sex, and graft size. Multivariable analysis was performed using the same explanatory factors.

RESULTS

Between 2007 and 2017, 1111 keratoplasties for infectious keratitis were registered in the Netherlands Organ Transplant Registry. The most common pathogens were viruses (n = 437), bacteria (n = 271), and Acanthamoeba (n = 121). Human leukocyte antigen (HLA) matching did not provide a significant survival benefit, whereas emergency procedures showed worse graft survival [hazard ratio (HR) = 0.40, P = 0.120; HR = 2.73, P < 0.001, respectively]. Graft size >8.5 mm was significantly worse than graft size 8.5 mm (HR = 2.062, P = 0.010). In therapeutic keratoplasty, graft survival was significantly worse for Acanthamoeba than viral keratitis (HR = 2.36, P = 0.008). In the multivariable model, adjusting for graft size, type, and reason for transplantation, viral and bacterial keratitis did not differ significantly in graft survival, and Acanthamoeba showed a significantly worse prognosis (vs. viral keratitis, HR = 2.30, P < 0.001; bacterial keratitis, HR = 2.65, P < 0.001).

CONCLUSIONS

Viral keratitis was the most common indication for transplantation, followed by bacterial and Acanthamoeba keratitis. HLA matching did not offer protection over elective non-HLA-matched procedures, whereas emergency procedures and grafts sized >8.5 mm showed poor survival. In optical keratoplasty, survival is high for all pathogens, whereas in therapeutic keratoplasty Acanthamoeba shows poor outcome.

Resveratrol regulates macrophage recruitment and M1 macrophage polarization and prevents corneal allograft rejection in rats

Introduction

Resveratrol is an immune modulator that can reduce M1 macrophage polarization in vitro. Reducing macrophage recruitment and M1 polarization can prevent corneal allograft rejection (CGR). In this study, rat corneal allograft rejection models were established to explore the effects of resveratrol on CGR and macrophages and the underlying mechanisms after corneal transplantation.

Methods

Corneal allograft models were established, and 100 mg/kg resveratrol was injected intraperitoneally. The corneal allografts were assessed clinically using the Holland rejection scoring system, anterior segment photography, and anterior segment optical coherence tomography. Corneal macrophages, pro-inflammatory cytokines, and corneal lymphatic vessels were detected using hematoxylin and eosin staining, immunofluorescence staining, and real-time quantitative polymerase chain reaction (qRT-PCR). Dendritic cells (DCs) in cervical lymph nodes were explored using flow cytometry. RNA sequencing experiments were conducted to identify the mechanisms through which resveratrol affected CGR. The results were verified using Simple Western analysis. Pro-inflammatory cytokines by macrophages in vitro were measured using qRT-PCR and enzyme-linked immunosorbent assays.

Results

Resveratrol significantly prolonged the survival of corneal grafts and reduced graft edema and central corneal thickness. Corneal macrophage recruitment and M1 macrophage polarization decreased significantly after corneal transplantation in the resveratrol group. Resveratrol also reduced pro-inflammatory cytokines in corneal grafts and suppressed the early generation of cornea lymphatic vessels and the recruitment of cornea inflammatory cells 14 days after surgery. Resveratrol decreased the proportion of DCs in ipsilateral cervical lymph nodes. The effect of resveratrol on CGR was related to the phosphatidylinositol 3-kinase/protein kinase-B (PI3K/Akt) pathway. Resveratrol reduced the secretion of pro-inflammatory cytokines by M1 macrophages in vitro.

Conclusion

Our findings suggest that resveratrol can reduce corneal macrophage recruitment and M1 macrophage polarization after corneal transplantation in rats and prevent CGR. The PI3K/Akt pathway may be an important mechanism that warrants further research.

Challenges of DMEK Technique with Young Corneal Donors' Grafts: Surgical Keys for Success-A Pilot Study

PURPOSE

To report on the surgical maneuvers recommended for a successful unfolding of very young donors in order to accomplish an uneventful Descemet Membrane Endothelial Keratoplasty (DMEK) surgery.

METHODS

Five patients (three females and two males, mean age 71.2 ± 6.7 years) with Fuchs endothelial cell dystrophy who underwent DMEK with very young donors (between 20 and 30 years old) were included. The following demographic data were assessed: donor's age, donor's endothelial cell density (ECD), preservation time, recipient's age and sex and unfolding surgical time. Best-corrected visual acuity (BCVA; decimal system), ECD and corneal central thickness (CCT) were assessed preoperatively and at 6-month follow-up.

RESULTS

Donors' mean age was 23.6 ± 3.6 years (range 21 to 30) and the mean ECD was 2748.6 ± 162.6 cells/mm2. All of them underwent an uneventful DMEK as a single procedure performed by one experienced surgeon (MAG) with a mean unfolding time of 7.2 ± 4.9 min (range 4 to 15). The essential steps, including patient preparation as well as DMEK graft implantation, orientation, unrolling and centering are detailed. At 6 months, BCVA was 0.6 ± 0.2, ECD was 1945.0 ± 455.5 cells/mm2 and CCT was 497.0 ± 19.7 microns.

CONCLUSIONS

We hereby present the keys to overcome tightly scrolled grafts of very young donors, which prove perfectly suitable for DMEK surgery. The graft shape tends towards a double-roll and specific maneuvers are strongly recommended.

Spontaneous intraocular lens extrusion through Gundersen conjunctival graft after multiple failed keratoplasties: A report of two cases

PURPOSE

To report the occurrence and the outcomes of 2 cases of spontaneous extrusion of 3-piece intraocular lens (IOL) through a Gundersen conjunctival flap performed for tectonic purposes after multiple failed penetrating keratoplasties (PKs).

METHODS

A 70-year-old woman (Patient #1) with severe dry eye disease who had undergone cataract surgery with posterior chamber 3-piece IOL implantation, multiple PKs and Gundersen conjunctival flap in her left eye presented with partial extrusion of the optic and the inferior haptic of the IOL through the conjunctival flap. Inferior symblepharon and keratinization of the entire ocular surface were also present. A 64-year-old diabetic man (Patient #2) with history of cataract surgery with a posterior chamber IOL implantation, multiple PKs for keratoconus and Gunderson conjunctival flap in his right eye presented with partial extrusion of IOL optic through the conjunctival flap.

RESULTS

Patient #1 refused a further surgery and IOL was removed at the slit lamp. Currently, 3 months after IOL extrusion, corneal perforation self-sealed, visual acuity of light perception is maintained, and the patient does not complain any symptoms of ocular discomfort or pain. In Patient #2, tectonic PK combined with IOL removal and anterior vitrectomy was performed. Currently, 1 month postoperatively corneal graft is clear, intraocular pressure is normal, and patient's vision is counting fingers.

CONCLUSIONS

In both cases, IOL extrusion occurred spontaneously through a Gunderson conjunctival flap. Including the underlying Tenon's capsule in the conjunctival graft could increase its tectonic support, potentially avoiding this complication.

The impact of donor diabetes on corneal transplant immunity

Corneal transplantation is the most common form of solid tissue grafting, with an approximately 80% to 90% success rate. However, success rates may decline when donor tissues are derived from patients with a history of diabetes mellitus (DM). To evaluate the underlying immunopathologic processes that cause graft rejection, we used streptozotocin-induced type 1 DM (DM1) and transgenic Lepob/ob type 2 DM (DM2) diabetic murine models as donors and nondiabetic BALB/c as recipients. DM resulted in an increased frequency of corneal antigen-presenting cells (APCs) with an acquired immunostimulatory phenotype. Following transplantation, recipients that received either type of diabetic graft showed increased APC migration and T helper type 1 alloreactive cells, impaired functional regulatory T cells, and graft survival. Insulin treatment in streptozotocin-induced diabetic mice led to an increased tolerogenic profile of graft APC, lower T helper type 1 sensitization, and a higher frequency of functional regulatory T cells with high suppressive capacity, reflected in increased graft survival. We conclude that both DM1 and DM2 in donors can impact corneal APC functional phenotype, rendering the tissue more immunogenic and thereby increasing the risk of graft failure.

A 7-year review of clinical characteristics, predisposing factors and outcomes of post-keratoplasty infectious keratitis: the Nottingham infectious keratitis study

Background/objectives

Post-keratoplasty infectious keratitis (PKIK) is a unique sight-threatening clinical entity which often poses significant therapeutic challenges. This study aimed to examine the clinical presentation, risk factors, management, and clinical outcomes of PKIK.

Methods

This was a retrospective study of all patients who presented to the Queen's Medical Centre, Nottingham, with PKIK between September 2015 and August 2022 (a 7-year period). Relevant data on types of keratoplasty, clinical presentations, causative microorganisms, management, and outcome were analyzed.

Results

Forty-nine PKIK cases, including four cases of interface infectious keratitis, were identified during the study period. The most common graft indications for PKP, DALK and EK were failed grafts (9, 37.5%), keratoconus (6, 54.5%) and Fuchs endothelial corneal dystrophy (FECD; 8, 57.1%), respectively. Staphylococcus spp. were the most commonly identified organisms (15, 50.0%). Bullous keratopathy (18, 36.7%), ocular surface disease (18, 36.7%), and broken/loose sutures (15, 30.6%) were the most common risk factors. Concurrent use of topical steroids was identified in 25 (51.0%) cases. Of 31 functioning grafts at presentation, 12 (38.7%) grafts failed at final follow-up with 15 (48.4%) patients retaining a CDVA of ≥1.0 logMAR. The overall estimated 5-year survival rate post-PKIK was 55.9% (95% CI, 35.9%-75.9%), with DALK having the highest survival rate [63.6% (95% CI, 28.9%-98.3%)], followed by EK [57.1% (95% CI, 20.4%-93.8%)] and PKP [52.7% (95% CI, 25.1%-80.3%)], though no statistical difference was observed (p=0.48).

Conclusions

PKIK represents an important cause of IK and graft failure. Bullous keratopathy, OSD and suture-related complications are the commonest risk factors, highlighting the potential benefit of prophylactic topical antibiotics (for unhealthy ocular surface) and early suture removal (where possible) in reducing the risk of PKIK. Graft survival may be higher in lamellar keratoplasty following PKIK but larger studies are required to elucidate this observation.

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.

Investigating the Role of TGF-β Signaling Pathways in Human Corneal Endothelial Cell Primary Culture

Corneal endothelial diseases are the leading cause of corneal transplantation. The global shortage of donor corneas has resulted in the investigation of alternative methods, such as cell therapy and tissue-engineered endothelial keratoplasty (TEEK), using primary cultures of human corneal endothelial cells (hCECs). The main challenge is optimizing the hCEC culture process to increase the endothelial cell density (ECD) and overall yield while preventing endothelial-mesenchymal transition (EndMT). Fetal bovine serum (FBS) is necessary for hCEC expansion but contains TGF-βs, which have been shown to be detrimental to hCECs. Therefore, we investigated various TGF-β signaling pathways using inhibitors to improve hCEC culture. Initially, we confirmed that TGF-β1, 2, and 3 induced EndMT on confluent hCECs without FBS. Using this TGF-β-induced EndMT model, we validated NCAM as a reliable biomarker to assess EndMT. We then demonstrated that, in a culture medium containing 8% FBS for hCEC expansion, TGF-β1 and 3, but not 2, significantly reduced the ECD and caused EndMT. TGF-β receptor inhibition had an anti-EndMT effect. Inhibition of the ROCK pathway, notably that of the P38 MAPK pathway, increased the ECD, while inhibition of the ERK pathway decreased the ECD. In conclusion, the presence of TGF-β1 and 3 in 8% FBS leads to a reduction in ECD and induces EndMT. The use of SB431542 or LY2109761 may prevent EndMT, while Y27632 or Ripasudil, and SB203580 or SB202190, can increase the ECD.

Microsporidial Stromal Keratitis in Post-Keratoplasty Eyes

PURPOSE

The purpose of this paper is to report the clinical manifestations, diagnostic evaluation, management and outcomes of microsporidial keratitis in post-keratoplasty eyes.

METHODS

This is a retrospective review of three patients diagnosed with microsporidial stromal keratitis in post-keratoplasty eyes between January 2012 and December 2021 at a tertiary referral center (Ospedali Privati Forlì "Villa Igea", Forlì, Italy).

RESULTS

All patients presented with fine multifocal granular infiltrates following keratoplasty for a presumed herpetic keratitis. No microorganisms were isolated from the corneal scrapings and no clinical response was observed with broad-spectrum antimicrobial therapy. In all cases, confocal microscopy demonstrated spore-like structures. The histopathologic examination of the excised corneal buttons confirmed the diagnosis of microsporidial stromal keratitis. Following therapeutic keratoplasty and treatment with an initial high dose and extended taper of topical fumagillin, clinical resolution was achieved in all eyes. The Snellen visual acuities at the final follow-up were 20/50, 20/63 and 20/32.

CONCLUSIONS

Prior to definitive surgery, confocal microscopy can be employed for the in vivo detection of pathogenic microorganisms such as Microsporidium. In post-keratoplasty eyes, therapeutic keratoplasty and an initial high dose of topical fumagillin with extended taper can allow the resolution of microsporidial stromal keratitis with a satisfactory visual prognosis.

Effects of Rho-Associated Kinase (Rock) Inhibitors (Alternative to Y-27632) on Primary Human Corneal Endothelial Cells

(1) Rho-associated coiled-coil protein kinase (ROCK) signaling cascade impacts a wide array of cellular events. For cellular therapeutics, scalable expansion of primary human corneal endothelial cells (CECs) is crucial, and the inhibition of ROCK signaling using a well characterized ROCK inhibitor (ROCKi) Y-27632 had been shown to enhance overall endothelial cell yield. (2) In this study, we compared several classes of ROCK inhibitors to both ROCK-I and ROCK-II, using in silico binding simulation. We then evaluated nine ROCK inhibitors for their effects on primary CECs, before narrowing it down to the two most efficacious compounds-AR-13324 (Netarsudil) and its active metabolite, AR-13503-and assessed their impact on cellular proliferation in vitro. Finally, we evaluated the use of AR-13324 on the regenerative capacity of donor cornea with an ex vivo corneal wound closure model. Donor-matched control groups supplemented with Y-27632 were used for comparative analyses. (3) Our in silico simulation revealed that most of the compounds had stronger binding strength than Y-27632. Most of the nine ROCK inhibitors assessed worked within the concentrations of between 100 nM to 30 µM, with comparable adherence to that of Y-27632. Of note, both AR-13324 and AR-13503 showed better cellular adherence when compared to Y-27632. Similarly, the proliferation rates of CECs exposed to AR-13324 were comparable to those of Y-27632. Interestingly, CECs expanded in a medium supplemented with AR-13503 were significantly more proliferative in (i) untreated vs. AR-13503 (1 μM; * p < 0.05); (ii) untreated vs. AR-13503 (10 μM; *** p < 0.001); (iii) Y-27632 vs. AR-13503 (10 μM; ** p < 0.005); (iv) AR-13324 (1 μM) vs. AR-13503 (10 μM; ** p < 0.005); and (v) AR-13324 (0.1 μM) vs. AR-13503 (10 μM; * p < 0.05). Lastly, an ex vivo corneal wound healing study showed a comparable wound healing rate for the final healed area in corneas exposed to Y-27632 or AR-13324. (4) In conclusion, we were able to demonstrate that various classes of ROCKi compounds other than Y-27632 were able to exert positive effects on primary CECs, and systematic donor-match controlled comparisons revealed that the FDA-approved ROCK inhibitor, AR-13324, is a potential candidate for cellular therapeutics or as an adjunct drug in regenerative treatment for corneal endothelial diseases in humans.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Intraoperative OCT for Lamellar Corneal Surgery: A User Guide

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

Early Visibility of Cellular Aggregates and Changes in Central Corneal Thickness as Predictors of Successful Corneal Endothelial Cell Injection Therapy

(1) Background: Cell injection therapy is an emerging treatment for bullous keratopathy (BK). Anterior segment optical coherence tomography (AS-OCT) imaging allows the high-resolution assessment of the anterior chamber. Our study aimed to investigate the predictive value of the visibility of cellular aggregates for corneal deturgescence in an animal model of bullous keratopathy. (2) Methods: Cell injections of corneal endothelial cells were performed in 45 eyes in a rabbit model of BK. AS-OCT imaging and central corneal thickness (CCT) measurement were performed at baseline and on day 1, day 4, day 7 and day 14 following cell injection. A logistic regression was modelled to predict successful corneal deturgescence and its failure with cell aggregate visibility and CCT. Receiver-operating characteristic (ROC) curves were plotted, and areas under the curve (AUC) calculated for each time point in these models. (3) Results: Cellular aggregates were identified on days 1, 4, 7 and 14 in 86.7%, 39.5%, 20.0% and 4.4% of eyes, respectively. The positive predictive value of cellular aggregate visibility for successful corneal deturgescence was 71.8%, 64.7%, 66.7% and 100.0% at each time point, respectively. Using logistic regression modelling, the visibility of cellular aggregates on day 1 appeared to increase the likelihood of successful corneal deturgescence, but this did not reach statistical significance. An increase in pachymetry, however, resulted in a small but statistically significant decreased likelihood of success, with an odds ratio of 0.996 for days 1 (95% CI 0.993-1.000), 2 (95% CI 0.993-0.999) and 14 (95% CI 0.994-0.998) and an odds ratio of 0.994 (95% CI 0.991-0.998) for day 7. The ROC curves were plotted, and the AUC values were 0.72 (95% CI 0.55-0.89), 0.80 (95% CI 0. 62-0.98), 0.86 (95% CI 0.71-1.00) and 0.90 (95% CI 0.80-0.99) for days 1, 4, 7 and 14, respectively. (4) Conclusions: Logistic regression modelling of cell aggregate visibility and CCT was predictive of successful corneal endothelial cell injection therapy.

Bowman's membrane lenticule tuck-in: A new approach for the management of neurotrophic ulcers

PURPOSE

To evaluate a new surgical method for managing nonhealing neurotrophic ulcers using a novel technique of tucking-in Bowman's membrane lenticule in the ulcer defect.

METHODS

A total of 22 eyes of 22 patients with neurotrophic ulcers of various etiologies and stages were included and underwent a surgical process where a donor Bowman's membrane lenticule was harvested and fashioned according to the lesion and tucked inside the ulcer after making a recess in anterior one-third of stroma all around 360 degrees. The primary outcomes measured were healing (stable epithelialization at 12 months) and best-corrected visual acuity (BCVA) improvement.

RESULTS

Twenty-two eyes of 22 patients with neurotrophic ulcers underwent Bowman's membrane lenticule tuck-in procedure. Complete re-epithelialization was achieved in 21 eyes (95.45%). The average healing time was 2.77 ± 0.79 weeks. The mean corneal thickness improved from 267.36 ± 94.56 mm preoperatively to 435.9 ± 47.71 mm at six months postoperatively. The mean BCVA also improved from 0.05 ± 0.07 preoperatively to 0.24 ± 0.24 postoperatively one year. One patient (4.54%) showed recurrence after one month, and the epithelial defect persisted till the end of the study.

CONCLUSION

Donor Bowman's membrane lenticule tuck-in for neurotrophic ulcers is a safe and highly effective treatment and requires minimal instruments and expertise.

Post-Keratoplasty Infectious Keratitis Caused by Elizabethkingia meningoseptica

BACKGROUND Microbial keratitis is a major complication of keratoplasty that is associated with serious ocular sequalae if not adequately treated. The purpose of this case report is to present a case of infectious keratitis following keratoplasty caused by the rare microorganism Elizabethkingia meningoseptica. CASE REPORT A 73-year-old patient presented to the outpatient clinic complaining of a sudden decrease of vision in his left eye. The right eye was enucleated during childhood due to ocular trauma and an ocular prosthesis was placed in the orbital socket. He underwent penetrating keratoplasty 30 years ago for corneal scar and repeated optical penetrating keratoplasty for failed graft in 2016. He was diagnosed with microbial keratitis following optical penetrating keratoplasty in the left eye. Corneal scraping of the infiltrate showed growth of the gram-negative bacteria Elizabethkingia meningoseptica. Conjunctival swab of the orbital socket of the fellow eye was positive for the same microorganism. E. meningoseptica is a rare gram-negative bacterium, which is not part of the normal ocular flora. The patient was admitted for close monitoring and was started on antibiotics. He showed significant improvement after treatment with topical moxifloxacin and topical steroids. CONCLUSIONS Microbial keratitis is a serious complication following penetrating keratoplasty. An infected orbital socket could be a risk factor of microbial keratitis of the fellow eye. A high index of suspicion, along with timely diagnosis and management, may improve the outcome and clinical response and reduce the morbidity associated with these infections. Prevention of infectious keratitis is essential and may be achieved by optimizing the ocular surface and treating the risk factors for infection.

Graft rejection in component keratoplasty

Among the various indications for keratoplasty, failed graft is one of the commonest indications in many published series. It is well known that the major cause of graft failure is endothelial rejection. In the last two decades, there has been a major paradigm shift in the surgical management of corneal diseases, and component keratoplasty has emerged from the concept of replacing the layer that is actually diseased, rather than replacing the full-thickness cornea with the traditional penetrating keratoplasty. This has resulted in improved outcomes and the risk of endothelial rejection has reduced drastically, thus expanding the survival time of the graft. In recent years, reports of graft rejection in component keratoplasty have emerged, with each having a different presentation and responding to a different line of treatment. This review aims to summarize the presentation, diagnosis, and management of graft rejections in component keratoplasty.

Corneal transplantation in aniridia-related keratopathy with a two-year follow-up period, an uncommon disease with precarious course

PURPOSE

The purpose of this study is to study the frequency, surgical transplantation technique and outcome in patients with aniridia-related keratopathy (ARK) with two-year follow-up period.

METHODS

A retrospective registry-study including all ARK cases performed in Sweden and Denmark between 2001 and 2016 and registered in the Swedish Cornea Transplant Registry.

RESULTS

A total of 36 eyes of 26 patients were subjected to corneal transplantation due to ARK during 2001 to 2016. Penetrating keratoplasty (PK) was the procedure of choice in 58.3% (n = 21) of the eyes, followed by a combination of PK and limbal stem cell transplantation in 13.9% (n = 5) and keratolimbal allograft in 13.9% (n = 5). Boston keratoprosthesis was used in 8.3% (n = 3), and anterior lamellar keratoplasty in 5.6% (n = 2). Thirteen of the procedures (36.1%) were retransplantations. Two years after surgery 26 cases were available to follow-up of which 16 of the grafts were functioning (61.5%). The median visual acuity showed a trend of improvement from hand motion to counting fingers.

CONCLUSIONS

A majority of the ARK cases (61.5%) had a graft providing useful vision for the patient 2 years after corneal transplantation, but the visual gain was modest at best. Longer follow-up time is required to evaluate functional graft outcomes. Despite the introduction of limbal stem cell transplantation as a suitable treatment, PK was the most common surgical method in the present study.

Establishing a Virtual Corneal Clinic: A Real-Time Teleophthalmology Approach

PURPOSE

Keratoplasty patients require regular and timely follow-ups. During this COVID-19 pandemic which restricted global travel, we developed a novel real-time, hybrid teleophthalmology approach to comanage international keratoplasty patients between Singapore and Indonesia.

METHODS

A retrospective consecutive observational study of 72 corneal patients (63 were postkeratoplasty) who attended a virtual corneal clinic (VCC) between June 2020 and April 2021 at JEC Eye Hospitals (JEC) in Jakarta, Indonesia. ZOOM Meeting software (Zoom Video Communication Inc, San Jose, CA) was used to simultaneously connect the Singapore corneal specialist at Eye & Cornea Surgeons (ECS), Singapore, using a real-time approach. Clinical examinations included full panels of video-linked corneal, glaucoma, and retinal imaging and investigations performed before real-time video-linked slit-lamp examination, with immediate clinical decision making between corneal specialists and patients.

RESULTS

VCC enabled effective real-time clinical evaluation and collaborative clinical decisions, with full patient interaction, with the aim of maintenance of graft clarity, visual function, and management of comorbidities-a) topical and systemic medications were adjusted in 79.2% of patients; b) further referrals to glaucoma, retinal, and oculoplastic subspecialists were made in 16.6% of cases; c) additional adjunctive surgical procedures were performed at JEC in 6.9% cases; and d) government permission was obtained for 4 patients (5.6%) to fly to Singapore for urgent corneal surgery.

CONCLUSIONS

The virtual corneal clinic is a novel real-time hybrid teleophthalmology approach which is effective in the comanagement of international keratoplasty patients and represents the advances in ophthalmic telemedicine.

Effect of Magnetic Microparticles on Cultivated Human Corneal Endothelial Cells

Purpose

To investigate effects of magnetic microparticles on movement of magnet controlled human corneal endothelial cells (HCECs).

Methods

Immortalized HCEC line (B4G12) and primary culture of HCECs were exposed to two commercially available magnetic micro- or nanoparticles, SiMAG (average size 100 nm) and fluidMAG (average size <1000 nm). Cell viability assays and reactive oxygen species production assays were performed. Cellular structural changes, intracellular distribution of microparticles, and expression levels of proteins related to cellular survival were analyzed. Ex vivo human corneas were exposed to microparticles to further evaluate their effects. Magnetic particle-laden HCECs were cultured under the influence of a neodymium magnet.

Results

No significant decrease of viability was found in HCECs after exposure to both magnetic particles at concentrations up to 20 µg/mL for 48 hours. However, high concentrations (40 µg/mL and 80 µg/mL) of SiMAG and FluidMAG significantly decreased viability in immortalized HCECs, and only 80 µg/mL of SiMAG and FluidMAG decreased viability in primary HCECs after 48 hours of exposure. There was relative stability of viability at various concentrations of magnetic particles, despite a dose-dependent increase of reactive oxygen species, lactate dehydrogenase, and markers of apoptosis. Ex vivo human cornea study further revealed that exposure to 20 µg/mL of SiMAG and fluidMAG for 72 hours was tolerable. Endocytosed magnetic particles were mainly localized in the cytoplasm. The application of a magnetic field during cell culture successfully demonstrated that magnetic particle-loaded HCECs moved toward the magnet area and that the population density of HCECs was significantly increased.

Conclusions

We verified short-term effects of SiMAG and fluidMAG on HCECs and their ability to control movement of HCECs by an external magnetic field.

Translational Relevance

A technology of applying magnetic particles to a human corneal endothelial cell culture and controlling the movement of cells to a desired area using a magnetic field could be used to increase cell density during cell culture or improve the localization of corneal endothelial cells injected into the anterior chamber to the back of the cornea.

A Novel Murine Model of Endothelial Keratoplasty

PURPOSE

The purpose of this study was to establish a murine model of endothelial keratoplasty.

METHODS

Endothelial keratoplasty (EK) was performed using C57BL/6 donor and BALB/c recipient mice. The central endothelium and Descemet membrane were removed from the recipient cornea, and a 1.5-mm posterior lamellar donor graft was made adherent to the recipient cornea with a small amount of viscoelastic. Mice were followed through slitlamp microscopy postoperatively, and OCT was used to assess the cornea and anterior chamber and measure central corneal thickness. Histology and immunohistochemistry were performed to confirm graft adherence and endothelial cell morphology.

RESULTS

Successfully attached EK grafts were visualized in all transplanted animals. Histology and immunostaining confirmed proper graft orientation and adherence, as well as the presence of donor endothelium on transplanted grafts. We observed maximal corneal edema in all animals at day 1 postoperatively which gradually subsided. EK graft survival was 97% at 8 weeks.

CONCLUSIONS

In this study, we describe a novel murine model for EK which we anticipate will enable detailed investigation into the cellular and molecular mechanisms involved in EK pathobiology.

Disparities in Access to Corneal Tissue in the Developing World

Corneal disease is a leading cause of blindness worldwide. For most blinding corneal conditions, keratoplasty is the only way of restoring sight. Unfortunately, access to corneal transplantation is widely variable, most notably due to the lack of suitable donor material. There exists significant disparity between the developed and developing world when it comes to access to cornea tissue, with supply often inversely proportional to burden of disease. The purpose of this review is to identify the current disparities in supply and demand of corneal donor tissue, understand how to access corneal tissue, and propose solutions that promote equitable care for patients with severe corneal disease.

[On the issue of separate designation of the pre-Descemet's layer in the structure of the cornea]

Selective exchange of pathologically altered retinal layers is currently considered the most practical approach in corneal transplantation. Deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK) are often performed as pathogenetically substantiated transplantation methods. The technique and the course of surgery, possible complications, and achieved outcomes, among other things, depend largely on the pre-Descemet's layer, which was described more than 10 years ago by several ophthalmologists in varying detail. In view of this, the main issue discussed in literature is the following: is the pre-Descemet's layer (Dua's layer) a separate (new) layer of the cornea, or is it an integral part of the stroma (the Feizi stroma)? This article continues the discussion on «separate designation of the pre-Descemet's layer in the structure of the cornea» and presents the view of the authors on this problem based on own experience, literature data, anatomical subdisciplines, as well as specific aspects of ophthalmological terminology, and with the use of extrapolation and analogies.

[Transplantation of the Bowman's layer in combined treatment of recurrent pterygium]

Pterygium is among the most frequent indications for extraocular ophthalmic surgery. The main method of pterygium treatment - its excision - is often combined with transplantation, non-transplantation, medication and other methods. However, the frequency of pterygium recurrence can exceed 35%, and the cosmetic and refraction outcomes satisfy neither the patient, nor the surgeon.

PURPOSE

The study analyses the technical capability and feasibility for transplantation of the Bowman's layer in the treatment of recurrent pterygium.

MATERIAL AND METHODS

The transplantation of the Bowmen's layer was performed according to the developed technique on 7 eyes with recurrent pterygium (7 patients aged 34 to 63 years). The combined surgery technique consisted of pterygium resection, laser ablation, autoconjunctival plasty, exposure to a cytostatic drug, non-suture transplantation of the Bowman's layer. Maximum length of the follow-up was 36 months. Analysis involved data from refractometry, visometry (without correction and with spectacle correction), and optical coherence tomography of the retina.

RESULTS

There were no complications in any of the studied cases. The cornea and the transplant retained transparency throughout the entire follow-up duration. 36 months after surgery mean spectacle-corrected visual acuity amounted to 0.86±0.2, topographic astigmatism - 1.48±1.4 diopters. Recurrence of pterygium was not observed. All patients were satisfied with the cosmetic outcomes of the treatment.

CONCLUSION

Non-suture transplantation of the Bowmen's layer recovers normal anatomy, physiology and transparency of the cornea after repeat surgical intervention for pterygium. No pterygium recurrences were observed throughout the entire follow-up after treatment with the proposed combined technique.

Management of post-keratoplasty ametropia

Even after a successful corneal transplant, patients experience severe refractive errors, impeding their rehabilitation and satisfaction. Refractive errors can be caused by recipient pathology and corneal thickness, as well as intraoperative factors such as donor-host discrepancy, recipient's eccentric trephination, vitreous length, wound apposition, technique of suturing, and suture material. Also, wound healing and the interim between keratoplasty and suture removal contribute to astigmatism. Lamellar keratoplasty outperforms penetrating keratoplasty in terms of endothelial cell loss and endothelial graft rejection, yet the risk of developing refractive errors is comparable. Nonsurgical interventions such as spectacles and lenses fail to provide desirable vision in cases with high astigmatism and corneal irregularity. When these limitations are encountered, surgical interventions including incisional keratotomy, wedge resection, laser refractive surgeries, intracorneal segments, and intraocular lens implantation are employed. However, occasionally, none of these approaches deliver the desired effects, leading to the need for a repeat keratoplasty.

Eye Donation: Knowledge, Beliefs, Awareness, and Willingness Among Ambulance Drivers in Central India

Aim

To determine the awareness about and willingness to donate eyes among ambulance drivers in Central India.

Design

Prospective, observational, noncomparative, and cross-sectional survey study.

Setting

Tertiary eye care center in Central India.

Methods

The present study used a structured questionnaire distributed to ambulance drivers during the eye donation fortnight (August 25-September 8, 2022). The questionnaire comprised four domains: awareness, knowledge beliefs, and willingness to donate eyes. The collected data were entered into an Excel sheet and analyzed using SPSS software.

Results

Forty-seven ambulance drivers participated in the study. All participants were men. The results showed that 48.9% (n = 23) of the ambulance drivers had completed elementary or middle school education. Furthermore, 27 (57%) participants were aware of eye donation; however, only 14 (29.7%) realized its importance. The source of information was mobile phones (n = 20, 42.6%). The common reason for the nondonation of eyes was lack of awareness (n = 14 29.7%). Thirty-five (74.5%) ambulance drivers were willing to donate their eyes, and the most common reason was the gratification derived from helping blind people.

Conclusion

The study revealed the need to improve awareness and knowledge about eye donation among the participants. Arranging short sessions round the year, addressing the myths associated with eye donation, and sharing motivational stories may help create awareness. Display of information and booklets on eye donation in the ambulance is likely to help in obtaining more corneas for transplantation.

Pars plana vitrectomy and therapeutic keratoplasty in endophthalmitis and infectious keratitis

PURPOSE

To describe the anatomical and functional outcomes of patients with infectious keratitis (IK) and secondary endophthalmitis who underwent penetrating keratoplasty (PK) after pars plana vitrectomy (PPV) assisted by temporary keratoprosthesis (TKP).

METHODS

An observational retrospective case series was performed. Data were collected from January 2013 to July 2020. Patients over 18 years old with a clinical and microbiological diagnosis of IK, and clinical, ultrasonographic, and or microbiological diagnosis of endophthalmitis were included. Anatomical success was defined as infection resolution with preservation of the ocular globe integrity. No change or improvement of best-corrected visual acuity (VA) at the last follow-up was considered as a functional success.

RESULTS

A total of 32 eyes of 32 patients were analyzed. The anatomic success was obtained in 87.5% eyes in which the infection was eradicated. The 63% patients maintained or improved their best-corrected VA, 37.5% ended up with hand motion VA.

CONCLUSIONS

Our results suggest that PPV assisted by TKP followed by PKP can be a good approach for treating patients with endophthalmitis secondary to IK while allowing further visual improvement after an optical PK. Further prospective studies need to be done to evaluate final visual rehabilitation of these patients.

Different Murine High-Risk Corneal Transplant Settings Vary Significantly in Their (Lymph)angiogenic and Inflammatory Cell Signatures

Purpose

Pathologic conditions in the cornea, such as transplant rejection or trauma, can lead to corneal neovascularization, creating a high-risk environment that may compromise subsequent transplantation. This study aimed to evaluate the impact of different types of corneal injury on hemangiogenesis (HA), lymphangiogenesis (LA) and immune cell pattern in the cornea.

Methods

We used five different corneal injury models, namely, incision injury, alkali burn, suture placement, and low-risk keratoplasty, as well as high-risk keratoplasty and naïve corneas as control. One week after incision and 2 weeks after all other different injuries, corneal HA and LA were quantified by morphometric analysis. In addition, immune cell patterns of the whole cornea and the recipient rim were analyzed by immunohistochemistry. Immune cells in the draining lymph nodes (dLNs) were quantified by flow cytometry.

Results

Different types of corneal injury caused significantly different HA and LA responses (both P < 0.0001). The infiltration of corneal macrophages, dendritic cells, neutrophils, major histocompatibility complex (MHC) II+ cells, CD4+ T cells, and CD8+ T cells varied significantly in different high-risk settings (all P < 0.0001). Both the expression of MHC II on macrophages (P = 0.0005) and the frequency of MHC II+ dendritic cells (P = 0.0014) in the draining lymph nodes were significantly different across the various high-risk scenarios.

Conclusions

Murine high-risk settings caused by different underlying pathologies vary significantly in their (lymph)angiogenic and inflammatory cell patterns. Therefore, anti(lymph)angiogenic or immunomodulatory strategies to prevent and/or treat immune responses after subsequent corneal transplantation may need to be customized according to their immune-vascular "signatures."

Local and Systemic Injections of Human Cord Blood Myeloid-Derived Suppressor Cells to Prevent Graft Rejection in Corneal Transplantation

Myeloid-derived suppressor cells (MDSCs) are therapeutic agents to prevent graft rejection in organ transplants by modulating inflammation. Herein, the immunosuppressive effect of human cord blood MDSCs on corneal allograft models was confirmed. CB-MDSCs were locally (subconjuctival, 5 × 10⁵) or systemically (intravenous, 1 × 10⁶) injected twice on days 0 and 7. A corneal transplantation model was established using C57BL/6 and BALB/c mice, and corneal graft opacity was measured to evaluate graft rejection up to 6 weeks. Results showed that graft survival in the MDSCs groups increased compared to vehicle groups after 42 days. Systemic and local MDSC administration inhibited the maturation (MHC-II^hi CD11c+) of dendritic cells (DCs) and the differentiation of interferon γ+ CD4+ Th1 in draining lymph nodes (LNs). However, vehicle groups increased the infiltration of CD3+ T cells and F4/80+ macrophages and produced prominent neovascular and lymphatic vessels into the graft site with increased mRNA expression of VEGF-A/C and VEGFR-1/R-3. Local MDSCs administration showed prominent anti-angiogenic/anti-lymphangiogenic effects even at lower MDSCs doses. Thus, CB-MDSCs could relatively suppress the infiltration of pathological T cells/macrophages into the corneas and the migration of mature DCs into draining LNs Therefore, ocular and systemic MDSCs administration showed therapeutic potential for preventing corneal allograft rejection.

Combined Corneal Transplant, Glaucoma Drainage Implantation, and Pars Plana Vitrectomy Outcomes in a Pediatric Population

PURPOSE

The combination of glaucoma drainage device (GDI), pars plana vitrectomy (PPV), and corneal transplantation is well reported in adults. However, little is known about the outcomes of such combined procedures in pediatric patients. We present a retrospective, single-center study to evaluate the safety and outcomes of concurrent GDI and/or PPV with corneal transplantation in patients 18 years and younger.

METHODS

Retrospective chart review of pediatric patients (aged 0-18 years) who received either corneal transplants or keratoprosthesis in combination with at least 1 additional procedure (either GDI and/or PPV) at the Illinois Eye and Ear Infirmary, Chicago, IL, between 2003 and 2017. Primary outcomes included vision, intraocular pressure, and cup-to-disc ratio (C/D). Secondary outcomes included the number of repeat surgeries and intraoperative and postoperative complications.

RESULTS

Thirty-six patients were included with a mean age of 8.4 years and an average follow-up of 49.7 months. Nineteen patients received corneal surgery, GDI, and PPV; 4 received corneal and GDI surgery; and 13 received corneal and PPV surgery. Of the 19 patients with all 3 procedures, 48% experienced an increase in vision with an average improvement of 0.9 lines at the last follow-up. Intraocular pressure decreased by an average of -7.2 mm Hg for all groups. Fifty-three percent of all patients experienced complications.

CONCLUSIONS

Combined keratoplasty, GDI, and PPV seems to be effective in the management of complex pediatric eye disease. However, owing to the high risk of complications in this vulnerable patient population, careful consideration must be taken when determining a patient's surgical candidacy for combined cornea/glaucoma/retina procedures.

Transcriptional Profiling Provides New Insights into Organ Culture-Induced Changes in Human Donor Corneas

Corneal transplantation is one of the most common forms of tissue transplantation worldwide. Donor corneal tissue used in transplantation is provided by eye banks, which store the tissue in culture medium after procurement. To date, the effects of cell culture on human corneal tissue have not been fully elucidated. Using the 3' RNA sequencing method for massive analysis of cDNA ends (MACE), we show that cultivation of corneal tissue leads to significant changes in a variety of molecular processes in human corneal tissue that go well beyond aspects of previously known culture effects. Functionally grouped network analysis revealed nine major groups of biological processes that were affected by corneal organ culture, among them keratinization, hypoxia, and angiogenesis, with genes from each group being affected by culture time. A cell type deconvolution analysis revealed significant modulations of the corneal immune cell profile in a time dependent manner. The results suggest that current culture conditions should be further refined and that prolonged cultivation may be detrimental. Recently, we showed that MACE enables transcriptional profiling of formalin-fixed and paraffin-embedded (FFPE) conjunctival tissue with high accuracy even after more than 10 years of storage. Here we demonstrate that MACE provides comparable results for native and FFPE corneal tissue, confirming that the technology is suitable for transcriptome analysis of a wide range of archived diseased corneal samples stored in histological archives. Finally, our data underscore the feasibility of bioinformatics cell-type enrichment analysis in bulk RNA-seq data to profile immune cell composition in fixed and archived corneal tissue samples, for which RNA-seq analysis of individual cells is often not possible.

Knowledge, awareness and attitude of eye donation among non-clinical staff of a tertiary eye hospital in South India

Purpose

This study aimed to evaluate the knowledge, awareness and attitude of eye donation among non-clinical staff of tertiary eye hospitals and to convey a positive attitude toward eye donation by enhancing their awareness and knowledge.

Methods

An online cross-sectional study was conducted among the non-clinical staff from all centers of a tertiary eye care hospital across Tamil Nadu. Quiz link was emailed to non-clinical staff of all the centers. On completion of the quiz, the participants viewed their respective scores and the correct answers to all questions. This activity was presumed to subsequently improve their knowledge and clear up the myths on eye donation.

Results

Two hundred twenty-eight non-clinical staff from 11 hospitals participated in the quiz. Mean age was 35.3 ± 9.8 years and 130 were female staff (57.05%). One hundred eighty-one participants (79.39%) scored over 50% of the total 17 queries. One hundred eighty-six (81.58%) and 142 (62.28%) participants scored over 50% in the awareness section and knowledge section, respectively. Eye bank volunteers (73, 32.02%) were the main source of information. Twenty-four (10.53%) had already taken pledge for eye donation and 175 (76.75%) were willing to pledge, 29 (12.72%) were not willing to pledge. Twenty-two out of these 29 (75.86%) had no specific reason for not pledging. Family, religious reasons, lack of clarity and fear were least cited reasons (13.79%).

Conclusion

Non-clinical staff of an eye hospital are easily approachable and are expected to be more knowledgeable by the general public around them. They might act as primary motivators in raising awareness within their family, friends, relatives and neighbors.

The Descemet Membrane Endothelial Keratoplasty (DMEK) "Wave Maneuver"

A novel technique for Descemet membrane endothelial keratoplasty (DMEK) graft handling and centration without the endothelium touching the posterior part of the anterior chamber (AC), is presented here. It is particularly suitable for vitrectomized eyes, deep AC, and AC intraocular lenses (ACIOLs), potentially reducing surgery time and endothelial cell loss during surgery. This retrospective interventional case series includes 27 eyes with complex ocular pathology. All utilized a “Wave maneuver” to center an early elevated graft without completing graft centration on the bottom of the AC. Successful graft attachment and centration were evaluated intra and post-operatively. Best-corrected visual acuity (BCVA), central corneal thickness (CCT), and donor endothelial cell density (ECD) were measured pre-operatively, and three and six months post-operatively. DMEK grafts were successfully attached and centered in all cases. No maneuver-related complications were observed intraoperatively. BCVA improved from a pre-operative 0.2 ± 0.63, to 0.43 ± 0.49 and 0.76 ± 0.51 at the three- and six-month follow-ups, respectively (p < 0.01). CCT decreased from a pre-operative 742 ± 118, to 546 ± 87 and 512 ± 67 at three and six months, respectively (p < 0.01). ECD decreased from 2878 ± 419 cells/mm2 to 1153 ± 466 cells/mm2 at three and six months, respectively (p < 0.01). The “Wave maneuver” may be very beneficial in DMEK cases where the AC is either very deep or the bottom of the AC is compromised. The “Wave maneuver” learning curve was brief.

Update on Pediatric Corneal Diseases and Keratoplasty

Managing pediatric corneal disorders is challenging as the prognosis of pediatric keratoplasty depends on several factors. Advancements in the genetic basis of congenital corneal diseases and investigations in congenital corneal conditions provide a better understanding of pediatric corneal conditions. Surgeons performing keratoplasty in children now have a choice of various techniques. Evolving surgical techniques of anterior lamellar and endothelial keratoplasties has expanded the management interventions in these pediatric corneal morbidity conditions; however, considerable concerns still exist in association with corneal transplantation in infants and children. Outcomes in pediatric keratoplasty depend upon the preoperative indications, the timing of surgical intervention, intraoperative and postoperative factors including the patient/care givers' compliance. Factors such as low scleral rigidity, higher rate of graft failure, need for frequent examinations under anesthesia, and difficulty in optimal visual acuity assessment still remain a considerable challenge in pediatric scenarios. In children, deprivation amblyopia as a result of the corneal opacification can adversely affect visual development, causing dense amblyopia. Outcomes to surgical interventions for management of corneal opacification in children is further compromised by the pre-existing amblyopia apart from the concerns of refractive outcome of the graft. Graft rejection, graft infection, amblyopia, and glaucoma continue to be serious concerns. In recent years both anterior and posterior lamellar keratoplasty techniques are being increasingly performed in pediatric eyes, which offer advantages in the form of lower risk of graft rejection. The timing of surgery, careful case selection, cautious intraoperative approach, and optimal postoperative management can improve the anatomical and functional outcome in difficult cases.

Changing trends in the corneal transplantation and the impact of the COVID-19 pandemic on corneal transplant recipient selection

PURPOSE

The aim of this study was to analyze the trends in the major indications and types of keratoplasty over a 15-year period and to determine the effect of the coronavirus disease-2019 (COVID-19) pandemic on the selection of corneal transplant recipients at a tertiary referral center in Turkey.

METHODS

We retrospectively reviewed the data of patients who underwent keratoplasty at the center from January 2006 to March 2021. The keratoplasty indications and types of surgery were evaluated after classification into three groups (period I - January 2006-December 2012; period II - January 2013-March 2020; COVID-19 period - April 2020-March 2021).

RESULTS

A total of 5016 corneal transplants were performed in 3862 patients. Lamellar keratoplasty (LK) techniques were found to demonstrate a statistically significantly increasing trend compared to penetrating keratoplasty in the period between 2006 and 2021 (χ² = 240.55, P < 0.001). The top 4 indications over the 15-year period were aphakic/pseudophakic bullous keratopathy (BK) (1105, 22%), keratoconus (1085, 21.6%), regraft (1084, 21.6%), and keratitis (645, 12.8%). The most common keratoplasty indication during the COVID-19 period was regraft (27, 54.0%), followed by BK (13, 26.0%) and corneal perforation (5, 10%).

CONCLUSION

BK was the most common keratoplasty indication at our clinic during the 15-year period. LK rates have been found to increase in recent years, although still not reaching the rates of developed countries. There was a marked decrease in the number of keratoplasties during the COVID-19 pandemic and patients requiring urgent keratoplasty or those who suffered from a painful eye were prioritized.

Influence of time to procurement, incubation and release of organ cultured donor corneas on graft failure after Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

The aim of the present study was to investigate whether the time from death to procurement, to preservation or the storage time of donor corneas preserved in organ culture influenced the clinical outcome of patients undergoing Descemet stripping automated endothelial keratoplasty (DSAEK) for Fuchs endothelial keratoplasty.

METHODS

We conducted a registry-based study on 776 patients undergoing DSAEK. Data on time from donor death to cornea retrieval (DRT), time from death to preservation (DPT), the preservation time and donor cornea characteristics: age, sex and endothelial cell density (ECD) at the time of release for surgery, were extracted from The Danish Cornea Bank Registry. Data on recipient follow-up were collected from a corneal graft registry. The primary outcome was presence of graft failure within a period from 2 months to 2 years after surgery. Secondary outcomes were DRT, DPT, ECD ≤2300 and gender mismatch between donor and recipient.

RESULTS

Graft failure occurred in 26 patients. The mean preservation time for failed grafts was 34.1 ± 10.0 days (mean ± SD) and 27.3 ± 10.6 days (mean ± SD) for the clear, functional grafts at the 2-year follow-up. A preservation time of >29 days compared with ≤29 days was associated with a lower survival (HR 2.33, 95% CI on 1.06-5.14, p = 0.036) and an increased risk of graft failure (RR 1.53, 95% CI on 1.11-2.10, p = 0.009). For the secondary outcome variables, no difference in the risk of graft failure was observed and did not appear to impact the survival rate of DSAEK patients.

CONCLUSION

Preservation time of donor cornea was associated with graft survival and a prolonged preservation time of more than 4 weeks seemed to lower the 2-year survival.