Keratoplasty Research Articles

Efficacy and Safety of Ab-Interno Canaloplasty in Post-Keratoplasty Patients: 3-Year Results.

To evaluate the effectiveness and safety of ab-interno canaloplasty (ABiC) for managing intraocular pressure (IOP) in patients following keratoplasty over a three-year period. This retrospective analysis focused on post-keratoplasty patients treated with ABiC with the iTrack microcatheter (Nova Eye Medical, Fremont, CA, USA) at a single institution. The study assessed the procedure's impact on IOP control, graft survival, and reliance on topical hypotensive medications, with additional observation for any postoperative complications. Surgical success criteria included the percentage of eyes with IOP ≤15mmHg, IOP ≤18mmHg, ≥20% IOP reduction, medication-free eyes, and eyes with concurrent IOP and medication reductions. ABiC was performed successfully in a cohort of 16 post-keratoplasty (7 penetrating keratoplasty and 9 endothelial keratoplasty (EK)) eyes. Preoperative mean IOP of 25.8±7.2mmHg was significantly reduced to 13.4±2.9mmHg (p<0.001) at 1 year postoperatively and maintained at 13.1±3.9mmHg (p=0.009) at 3 years postoperatively. The mean number of glaucoma medications was 3.5±1.7 at baseline, 2.8±1.3 at 1 year (p=0.107), and 2.5±1.2 at 3 years postoperatively (p=0.088). Eight eyes (66.7%) maintained IOP ≤ 15mmHg, and 10 eyes (83.3%) maintained ≥ 20% IOP reduction at 3 years. The mean IOP and medication reductions from baseline at 3 years were -49.2% and -28.6%, respectively. Graft clarity was preserved in all patients except for one case of late graft failure that necessitated a repeat EK procedure. Post-ABiC complications included transient hyphema in two patients, neither of which led to long-term adverse outcomes. ABiC appears to be an effective and safe surgical intervention for sustained IOP reduction in post-keratoplasty patients. Graft survival trends are encouraging, and there was a low incidence of complications over a three-year follow-up period.

Antifungal resistance, clinical outcome and clinico-microbiological correlation in ocular infections due to common melanized fungi Curvularia lunata and Lasiodiplodia theobromae in South India.

Aim. Melanized fungi were rarely studied for their antifungal resistance (AFR) or clinical outcome, despite rising incidence of melanized fungal ocular infections and AFR in general. We report the antifungal resistance patterns, clinical outcome and clinico-microbiological correlation in two commonly isolated melanized fungi from ocular infections, Curvularia lunata and Lasiodiplodia theobromae, at a tertiary eyecare centre in South India.Gap statement. Despite melanized fungi accounting for a significant proportion of ocular fungal infections in the Indian subcontinent, and despite there being a limited selection of effective antifungal agents available for these infections, the existing data and studies on these issues remain sparse. Therefore, this study aimed to investigate the prevalence of antifungal resistance in two of the most common melanized fungal pathogens in ocular infections, Curvularia lunata and Lasiodiplodia theobromae and correlate it with the treatment given and the clinical outcome in patients.Methodology. Electronic medical records provided the clinical data. Standard broth microdilution was performed for antifungal susceptibility testing (AFST) in 30 isolates (17 C. lunata and 13 L. theobromae) for amphotericin B and natamycin (polyenes): voriconazole, ketoconazole, posaconazole, itraconazole and fluconazole (azoles) and caspofungin (echinocandin). Multidrug resistance (MDR) was defined as resistance to more than or equal to two classes of antifungals. DNA sequencing was performed for the isolates for species confirmation. The multivariate analysis was done for determining poor prognostic factors.Results. AFST showed highest susceptibility of study isolates for voriconazole (83.3% isolates), followed by natamycin (80%), fluconazole (80%), itraconazole (76.7%), ketoconazole (70%), posaconazole (66.7%), caspofungin (66.7%) and lastly amphotericin B (63.3%). All patients empirically received topical natamycin; additional oral ketoconazole/intraocular voriconazole was administered in select few. MDR was strongly associated with poor clinical outcome (multivariate analysis: P = 0.03, odds ratio = 7.8). All patients had microbial keratitis, one progressed to endophthalmitis. Additionally, therapeutic penetrating keratoplasty was required in 40% of cases. Globe salvage was possible in 80% patients, though good visual outcome was seen in only half of them. Both, anatomical and visual outcomes, were poor in 20% of patients. DNA sequencing showed C. lunata as the highest study species.Conclusion. C. lunata and L. theobromae showed varying in vitro antifungal susceptibility and clinical outcome in ocular infections. Voriconazole had significantly higher activity, while amphotericin B had lower activity in vitro for these melanized fungi. MDR isolates showed poorer clinical outcome.

A 13-year descriptive study of corneal transplants at a tertiary, teaching hospital in northwest Iran

A 13-year descriptive study of corneal transplants at a tertiary, teaching hospital in northwest Iran

TRANSPLANTE DE CÓRNEA, UMA REVISÃO INTEGRATIVA

Currently, cornea transplantation is the transplant performed in the largest number and with the best success rates. This article sought to bring together the main information about corneal transplantation, including indications, procedures and complications, in order to facilitate access to knowledge about this surgery. To this end, an integrative literature review was carried out with six well-defined steps, including defining the guiding question, searching for articles in specific databases and clear inclusion/exclusion criteria. The descriptors “cornea transplant”, “corneal transplant”, “indications”, “procedures” and “complications” were crossed in the following databases: Virtual Health Library (VHL); National Library of Medicine (PubMed MEDLINE), Scientific Electronic Library Online (SCIELO) and EbscoHost. The final selection included 20 articles. The data collected made it possible to identify some characteristics and statistical data on cornea transplantation. The results include main procedures and techniques, indications, risks, complications and epidemiology. The review concluded that the most used procedure is still penetrating keratoplasty, despite the various evolutions observed; The main indications vary from region to region, but overall the most prevalent was bullous keratopathy and the most prevalent complication is graft failure due to rejection.

Scleral lens fitting after paediatric limbal dermoid removal

Purpose. This case report describes the management of refractive error and amblyopia using a scleral lens fitted to the eye of a young child with an irregular cornea resulting from limbal dermoid removal and corneal transplant in infancy. Material and Methods. A young infant was initially fitted with spectacles and occlusion therapy following the surgical excision of a limbal dermoid and full thickness corneal transplant. The vision did not improve in spite of patching so the child was referred for contact lens fitting. Various iterations of scleral lens fitting were carried out. Results. Scleral lens fitting was attempted from the age of 2 years but transplant rejections, the COVID-19 pandemic and variable cooperation meant that adequate lens wear could not be achieved in the early stages. In addition, the corneal shape changed during the course of the fitting. During these periods, spectacle wear and occlusion therapy were maintained until a good lens fit could be achieved following several modifications. Treatment is ongoing but at the age of 5 years, the visual acuity is 0.24 logMAR letters. Conclusion. Scleral lenses can be used to habilitate the vision in an eye with an irregular cornea but when scleral lens wear is not possible, it is important to persevere with spectacle correction and patching therapy. Several iterations of scleral lenses may be needed as the eye changes and the child grows.

Corneal Artificial Endothelial Layer (EndoArt): Literature Review and Our Experience.

Background/Objectives: The objective of this study was to examine the morphological corneal changes and outcomes following the implantation of an artificial endothelial layer (EndoArt) in patients with chronic corneal oedema. Methods: A systematic review of the literature was conducted alongside a detailed analysis of two clinical cases with chronic corneal oedema that were treated using EndoArt. Our experience with these two cases is included to provide practical insights and real-world outcomes. Results: Across the 24 cases reported (including the two presented here), an analysis was possible in 23 cases. Notably, 82% of patients had undergone at least one previous corneal transplant, with 39% having undergone three or more transplants. Additionally, 78% of cases had ocular comorbidities, with glaucoma surgery being the most prevalent (83%), which could have impacted visual outcomes. The follow-up period ranged from 3 to 17 months with a median of 3 months. After EndoArt implantation, the average reduction in the central corneal thickness (CCT) was 29%, and the rebubbling rate was 47.8%, with some cases requiring no rebubbling, while others required it up to 100% of the time. Visual acuity significantly improved from a mean best-corrected visual acuity (BCVA) value of 1.61 ± 0.5 logMAR to 1.07 ± 0.59 logMAR (p < 0.001). The CCT decreased from 771 ± 146 µm to 580 ± 134 µm (p < 0.001). These findings are consistent with our experience. Conclusions: EndoArt shows promise as an alternative treatment for chronic corneal oedema in complex cases where conventional corneal transplantation has failed or carries a high risk of failure. The morphological changes observed using anterior segment optical coherence tomography (OCT) and in vivo confocal microscopy (IVCM) were similar to those reported after endothelial keratoplasty, with the notable exception of the absence of the hyper-reflective donor-host interface.

Inhibiting corneal transplantation rejection via lymphatic vessel ligation in a novel murine model

The lymphatic system is a crucial contributor to allograft rejection after corneal transplantation. However, no surgical procedures for the central pathway where conjunctival lymphatic vessels converge have been investigated. Therefore, we aimed to establish a murine model of lymphatic vessel ligation and evaluate its inhibitory effect on corneal allograft rejection. A tracer was used to visualise lymphatic vessels, and complications were evaluated. A surgical technique was developed to block the lymphatic vessels. Corneas from C57BL/6 mice were transplanted into BALB/c mice divided into two groups—one with and one without lymphatic vessel ligation, to evaluate their effects on allograft rejection. Graft opacity scores were evaluated for 8 weeks, and immunohistochemistry was used to quantify angiogenesis and lymphangiogenesis. 20% trypan blue used as a tracer showed clear inflow with no complications. The two sutures and cyanoacrylate glue combination demonstrated a blocking effect after 25 days and was thus used for lymphatic ligation. Three and nine out of fourteen eyes showed rejection at 8 weeks post-surgery in the lymphatic vessel ligation and control groups, respectively. Furthermore, neovascularisation and lymphangiogenesis significantly decreased in the lymphatic vessel ligation group. Overall, we present a novel therapeutic strategy for corneal transplantation.

Integrated environmental and health economic assessments of novel xeno-keratografts addressing a growing public health crisis

Tissue scarcity poses global challenges for corneal transplantation and public health. Xeno-keratoplasty using animal-derived tissues offers a potential solution, but its environmental and economic implications remain unclear. This study evaluated two xeno-keratoplasty procedures at a single institution: (1) native corneas (Option 1) and (2) tissue-engineered corneal scaffolds derived from slaughterhouse waste (Option 2). Life cycle assessment (LCA) quantified environmental impacts across 18 midpoint indicators, while cost-effectiveness analysis (CEA) incorporated cost and environmental impact using two approaches. Option 1 exhibited significantly lower environmental impact than Option 2 across most indicators, primarily due to the energy and equipment demands of cell culture in Option 2. Both CEA approaches (carbon offset pricing and utility decrement) demonstrated cost-effectiveness dominance for Option 1. Xeno-keratoplasty using native corneas (Option 1) appears more environmentally and economically favorable than tissue-engineered scaffolds (Option 2) in the current analysis. Future studies could explore diverse xeno-keratoplasty techniques for optimizing sustainability.

Influence of surgeon learning on outcomes in new ophthalmic procedures: quantified nationwide evidence in endothelial corneal transplantation

AimsTo investigate the impact of surgeon learning on endothelial keratoplasty (EK) procedure outcomes.MethodsA prospective nationwide registry study of EK grafts in patients aged at least 21 years with Fuchs endothelial...

Treatment of equine keratomycosis, part 1: selection of appropriate therapy based on clinical presentation and diagnostic testing improves clinical outcomes.

To determine clinical outcome, treatment costs, and hospitalization duration in horses treated for keratomycosis and identify ophthalmic examination and diagnostic results associated with these outcomes. This was a retrospective study of 126 equine keratomycosis cases between 2004 and 2020 with fungal infection confirmed on cytology, culture, and/or histopathology and a minimum of 1-month follow-up. Details of the ophthalmic examination, diagnostic test results, and treatment and cost outcomes were recorded. Outcomes of interest were analyzed by treatment type. The relationship of patient and diagnostic test variables to the outcomes of interest was determined via logistic and linear regression models. Globe retention and positive visual outcome occurred in 82.5% and 78.9% of medically and 88.4% and 85.5% of surgically treated cases, respectively. While not statistically significant, there were more positive clinical outcomes with surgery; in recent years, the globe and vision were preserved in 94.7% of cases following penetrating keratoplasty. The choice to pursue surgery was related to lesion depth. Medical treatment was associated with statistically shorter hospitalization times and lower total and hospitalization invoices compared to all surgical treatments. Diagnosis of stromal abscess was associated with higher total invoice and longer hospitalization times compared to ulcerative keratomycosis, although clinical outcomes were similar. Overall positive clinical outcomes were achieved despite the severity of the disease in many cases, highlighting the need for appropriate treatment selection based on clinical presentation. Expanding knowledge of clinical decision-making, treatment options, and associated clinical and financial outcomes may further improve outcomes for equine keratomycosis patients.

Acquired immunostimulatory phenotype of migratory CD103+ DCs promotes alloimmunity following corneal transplantation.

After transplantation, Th1-mediated immune rejection is the predominant cause of graft failure. Th1 cell sensitization occurs through complex and context-dependent interaction among antigen-presenting cell subsets, particularly CD11b+ DCs (DC2) and CD103+ DCs (DC1). This interaction necessitates further investigation in the context of transplant immunity. We used well-established preclinical models of corneal transplantation and identified distinct roles of migratory CD103+ DC1 in influencing the outcomes of the grafted tissue. In recipients with uninflamed corneal beds, migratory CD103+ DC1 demonstrate a tolerogenic phenotype that modulates the immunogenic capacity of CD11b+ DC2 primarily mediated by IL-10, suppressing alloreactive CD4+ Th1 cells via the PD-L1/PD-1 pathway and enhancing Treg-mediated tolerance via αvβ8 integrin-activated TGF-β1, thus facilitating graft survival. Conversely, in recipients with inflamed and vascularized corneal beds, IFN-γ produced by CD4+ Th1 cells induced migratory CD103+ DC1 to adopt an immunostimulatory phenotype, characterized by the downregulation of regulatory markers, including αvβ8 integrin and IL-10, and the upregulation of IL-12 and costimulatory molecules CD80/86, resulting in graft failure. The adoptive transfer of ex vivo induced tolerogenic CD103+ DC1 (iDC1) effectively inhibited Th1 polarization and preserved the tolerogenic phenotype of their physiological counterparts. Collectively, our findings underscore the essential role played by CD103+ DC1 in modulating host alloimmune responses.

In Vivo Imaging and Evaluation of CornealBiomechanics After Corneal Transplantation by Optical CoherenceElastography.

Postoperative corneal biomechanical evaluation is of great significance in clinical monitoring and management since corneal transplantation is one of the main methods to improve visual function. In this paper, we propose an OCE system based on a small ultrasound transducer to realize the in vivo detection of postoperative corneal elasticity in different directions. It was first validated and analyzed by different agar, and then the elasticity changes in normal cornea and post-transplant corneal implants and implant beds were further investigated. Compared with normal corneas, the shear wave velocity of the postoperative cornea decreased from 7.42 ± 1.71 m/s to 4.95 ± 0.35 m/s. Meanwhile, the shear wave velocity of the corneal implant bed was lower than that of the implanted sheet. Therefore, this study reports the first biomechanical measurement of corneal grafts based on the OCE technique, which might provide a potential tool for the postoperative evaluation of clinical patients.

Late corneal ectasia after penetrating and deep anterior lamellar keratoplasty for keratoconus.

To investigate tomographic features of late corneal ectasia after keratoplasty for keratoconus and compare penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) in terms of incidence, time of onset and risk factors of corneal ectasia. Sixty eyes with PK and 30 eyes with DALK operated between 1999 and 2021 were analyzed. Final Pentacam scans were evaluated together with vision and previous topographies. Main outcome measures were vision, K values, apparent thinning on graft-host cornea and the difference between opposing quadrants in the thinnest point measurements. Anterior segment optic coherence tomography was performed for further evaluation. Mean follow-up was 127.2mo (24-282mo) in PK, and 64.3mo (24-144mo) in DALK. K max was higher in DALK (60.6 vs 56.7 D, P=0.012). Inferior recipient was thinner (595.9 µm) in PK than DALK (662.2 µm, P=0.021), due to longer follow-up. Overall corneal ectasia rate was 20.0% within 24y. Ectasia rate was the same (6.7%) in DALK 2/30 and in PK 4/60 in 10y and 13.3% in 12y (4/30 and 8/60, respectively). It increased to 23.3% (14/60) in PK over 24y. While ectasia was not seen before 7y in PK, it could be seen in DALK starting from the 5th year. The intervals between keratoplasty and ectasia were 144.5mo in PK and 99mo in DALK. Inferior recipient was significantly thinner in 18 eyes with ectasia (502.7 µm) compared to 76 non-ectasia (649.1 µm, P=0.000). Inferior graft was thinner (561.0 vs 620.4 µm, P=0.006), K max (63.3 vs 56.5 D, P=0.000), and anterior elevation was higher in ectasia (89.1 vs 48.6 µm, P=0.002). Accelerated crosslinking was performed on 5 eyes. Inferior-superior recipient and inferior graft thinning on tomography, with high K max and anterior elevation emerge as the most reliable criteria for the diagnosis of late ectasia. The incidence of corneal ectasia increases with the time.

Changing indications for and trends of keratoplasty in a tertiary comprehensive hospital in northern part of China from 2002 to 2021: a 20-year review

ObjectiveTo investigate indications and surgical procedures of keratoplasty in a tertiary comprehensive hospital in northern part of China over a 20-year period.MethodsAll patients undergoing keratoplasty between January 1, 2002 to December 31, 2021 in a tertiary comprehensive hospital in northern part of China were retrospectively reviewed. The annual proportion of keratoplasty indications and surgical procedures was recorded and analyzed.ResultsA total of 8266 keratoplasty procedures were included. Leading indications were keratoleukoma (n = 2108, 25.50%), followed by regraft (n = 1453 ,17.58%), corneal endothelial dysfunction (n = 1085, 13.13%), and keratoconus (n = 922,11.15%). A decreasing trend was observed for keratoleukoma (P < 0.01) and an increasing trend for corneal endothelial dysfunction (P < 0.01), regraft (P = 0.012), corneal limbal dermoids (P < 0.01) and congenital corneal opacity (P < 0.01). From 2002 to 2021, the proportion of penetrating keratoplasty (PK) had decreased from 73.95% (2002 to 2006) to 53.49% (2017 to 2021). On contrary, anterior lamellar keratoplasty (ALK) (459–705, 26.05-31.96%, P = 0.034) and endothelial keratoplasty (EK) (0-321, 0.00-14.55%, P < 0.01) became more prevalent from 2002 to 2021. For cases with corneal endothelial dysfunction, EK became the preferred technique (74.72%) in the recent 5 years.ConclusionOver the past 20 years, keratoleukoma and regraft have been the leading indications for keratoplasty. A noticeable shift in surgical preference from PK to DSAEK and ALK is evident, with key indications for keratoplasty including keratoleukoma, regraft, limbal dermoids, endothelial dysfunction, and keratoconus, respectively.

How do intraocular lens materials influence the outcome of cataract surgery?

This review summarizes the evidence on the effect of intraocular lens (IOL) material on the outcomes of cataract surgery, as well as on the surgical procedure itself. Differences in capsular biocompatibility between IOL materials lead to variations in capsular stability and posterior capsule opacification (PCO), while differences in uveal biocompatibility affect postoperative inflammatory response. Refractive outcomes are affected by both incision size and the rotational stability of toric IOLs. Small incision sizes favour hydrophilic IOLs. Rotational stability of hydrophobic and hydrophilic IOLs were comparable in recent studies. Visual outcomes are affected by chromatic aberrations, dysphotopsia, lens opacifications and PCO. Hydrophilic IOLs are associated with reduced chromatic dispersion. Hydrophobic IOL opacifications are caused by sub-surface glistenings, while hydrophilic IOL opacifications are due to surface calcifications. Some surgeries, including pars plana vitrectomy and lamellar corneal transplants, were shown to increase the risk of IOL calcifications, although the mechanism is still unknown. Hydrophilic IOLs have greater ease of manipulation, greater resistance to IOL damage, and higher uveal biocompatibility. Hydrophobic IOLs show better PCO prevention than hydrophilic IOLs, and should be preferred in highly myopic eyes where Nd:YAG capsulotomy might increase the risk of retinal detachment.

Advancements in Hydrogels for Corneal Healing and Tissue Engineering.

Hydrogels have garnered significant attention for their versatile applications across various fields, including biomedical engineering. This review delves into the fundamentals of hydrogels, exploring their definition, properties, and classification. Hydrogels, as three-dimensional networks of crosslinked polymers, possess tunable properties such as biocompatibility, mechanical strength, and hydrophilicity, making them ideal for medical applications. Uniquely, this article offers original insights into the application of hydrogels specifically for corneal tissue engineering, bridging a gap in current research. The review further examines the anatomical and functional complexities of the cornea, highlighting the challenges associated with corneal pathologies and the current reliance on donor corneas for transplantation. Considering the global shortage of donor corneas, this review discusses the potential of hydrogel-based materials in corneal tissue engineering. Emphasis is placed on the synthesis processes, including physical and chemical crosslinking, and the integration of bioactive molecules. Stimuli-responsive hydrogels, which react to environmental triggers, are identified as promising tools for drug delivery and tissue repair. Additionally, clinical applications of hydrogels in corneal pathologies are explored, showcasing their efficacy in various trials. Finally, the review addresses the challenges of regulatory approval and the need for further research to fully realize the potential of hydrogels in corneal tissue engineering, offering a promising outlook for future developments in this field.

Molecular and Cellular Mechanisms of the Therapeutic Effect of Mesenchymal Stem Cells and Extracellular Vesicles in Corneal Regeneration

The cornea is a vital component of the visual system, and its integrity is crucial for optimal vision. Damage to the cornea resulting from trauma, infection, or disease can lead to blindness. Corneal regeneration using mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (MSC-EVs) offers a promising alternative to corneal transplantation. MSCs are multipotent stromal cells that can differentiate into various cell types, including corneal cells. They can also secrete a variety of anti-inflammatory cytokines and several growth factors, promoting wound healing and tissue reconstruction. This review summarizes the current understanding of the molecular and cellular mechanisms by which MSCs and MSC-EVs contribute to corneal regeneration. It discusses the potential of MSCs and MSC-EV for treating various corneal diseases, including corneal epithelial defects, dry eye disease, and keratoconus. The review also highlights finalized human clinical trials investigating the safety and efficacy of MSC-based therapy in corneal regeneration. The therapeutic potential of MSCs and MSC-EVs for corneal regeneration is promising; however, further research is needed to optimize their clinical application.

The impact of family history on corneal donation and transplantation attitudes: a survey-based study

Objective: To assess how having a first-degree relative who underwent corneal transplantation influenced people’s attitudes regarding corneal donation and transplantation. Method: The cross-sectional study was conducted between March 15 and April 15, 2023, in the Ophthalmology outpatient department and cornea division of Necmettin Erbakan University Faculty of Medicine Hospital, Konya, Turkiye, and comprised first-degree relatives of patients who had undergone corneal transplantation in group A and controls matched age and gender without family history of transplantation in group B. All the participants filled out a 13-item survey form regarding socio-demographic characteristics and their perspectives on corneal transplantation and donation. Data was analysed using SPSS 20. Results: Of the 263 subjects, 133(50.6%) were in group A; 78(58.6%) females and 55(41.4%) males with mean age 46.5±15.2 years. There were 130(49.4%) subjects in group B; 70(53.8%) females and 60(46.32%) males with mean age 44.3±15.8 years (p&gt;0.05). There were 110(82.7%) participants in group A and 72(55.4%) in group B who knew what corneal transplantation meant (p&lt;0.001). In group A, 81(60.9%) subjects wanted to donate their corneas after death compared to 40(30.8%) in group B (p&lt;0.001). In group A, 108(83.7%) participants stated that a first-degree relative’s corneal transplantation positively affected their view of organ and tissue donation. Conclusion: Individuals whose first-degree relatives had had a cornea transplant showed higher awareness of cornea transplantation and willingness to donate their corneas. Key Words: Cornea transplantation, Keratoplasty, Transplant donors, Awareness, Family medical history.

Excimer Laser-Assisted Deep Anterior Lamellar Keratoplasty Versus Penetrating Keratoplasty for Patients With Keratoconus: A Retrospective Analysis From the Homburg Keratoconus Center.

To evaluate the outcome of excimer laser-assisted deep anterior lamellar keratoplasty (Exc-DALK) and penetrating keratoplasty (Exc-PKP) for keratoconus (KC). We included 123 eyes and compared the outcome of 30 eyes undergoing big-bubble Exc-DALK after stromal debulking (G1) against a matched group of 83 eyes undergoing Exc-PKP (G2) in our department. G2 was created after performing a pseudorandom stratified bootstrapping of our PKP database starting with 2802 surgeries with removal of any bias. Main outcomes included best corrected visual acuity (BCVA), spherical equivalent (SE), tomographic changes, and endothelial cell density (ECD). Data were compared preoperatively, postoperatively with 2 double-running cross-stitch sutures according to Hoffmann [2 and 10 months postoperatively (T1 and T2)], after first suture removal [15 months postoperatively (T3)], and after final suture removal [26 months postoperatively (T4)]. Preoperatively, all parameters were comparable without significant differences. At T1, G1 showed significantly better BCVA (P = 0.01), lower SE (P = 0.04), lower anterior and posterior topographic astigmatism (ATA and PTA, P < 0.01), lower maximal keratometry (P = 0.02), and lower central corneal thickness (P < 0.01). At T2, G1 showed significantly better BCVA (P = 0.04), lower PTA (P < 0.01), and higher ECD (P < 0.01). At T3, G1 showed significantly lower ATA (P = 0.01) and PTA (P < 0.01) and higher ECD (P = 0.02). At T4, G1 showed significantly lower PTA and higher ECD (P < 0.01) but no significant difference in BCVA (P = 0.07). Exc-DALK provided faster visual rehabilitation and represented an endothelial cell-sparing method compared with Exc-PKP. After final suture removal, Exc-DALK showed noninferior outcomes compared with Exc-PKP if the graft was placed on naked Descemet membrane.

Current Scenario and Future Perspectives of Porcine Corneal Xenotransplantation.

Corneal diseases represent a significant cause of blindness worldwide, with corneal transplantation being an effective treatment to prevent vision loss. Despite substantial advances in transplantation techniques, the demand for donor corneas exceeds the available supply, particularly in developing countries. Cornea xenotransplantation has emerged as a promising strategy to address the worldwide scarcity, notably using porcine corneas. In addition to the inherent immune privilege of the cornea, the low cost of porcine breeding and the anatomical and physiological similarities between humans and pigs have made porcine corneas a viable alternative. Nonetheless, ethical concerns, specifically the risk of xenozoonotic transmission and the necessity for stringent biosafety measures, remain significant obstacles. Moreover, the success of xenotransplantation is compromised by innate and adaptive immune responses, which requires meticulous consideration and further studies. Despite these challenges, recent breakthroughs have further contributed to reducing immunogenicity while preserving the corneal architecture. Advances in genetic engineering, such as the use of CRISPR-Cas9 to eliminate critical porcine antigens, have shown promise for mitigating immune reactions. Additionally, new immunosuppressive protocols, such as have techniques like decellularization and the use of porcine-derived acellular matrices, have greatly increased graft survival in preclinical models. Future research must focus on refining immunomodulatory strategies and improving graft preparation techniques to ensure the long-term survival and safety of porcine corneal xenotransplantation in clinical trials in humans.