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.

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.

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.