Search Results (154)

Corneal diseases are among the leading causes of blindness worldwide and the standard treatment is the transplantation of corneal donor tissue. Treatment for cornea-related visual impairment and blindness is, however, often constrained by the global shortage of suitable donor grafts. To alleviate the shortage of corneal donor tissue, new treatment options have been explored in the last decade. The discovery of induced pluripotent stem cells (iPSCs), which has revolutionized regenerative medicine, offers immense potential for corneal repair and regeneration. Using iPSCs can provide a renewable source for generating various corneal cell types, including corneal epithelial cells, stromal keratocytes, and corneal endothelial cells. To document the recent progress towards the clinical application of iPSC-derived corneal cells, this review summarizes the latest advancements in iPSC-derived corneal cell therapies, ranging from differentiation protocols and preclinical studies to the first clinical trials, and discusses the challenges for successful translation to the clinic. Full article

The cornea, the transparent anterior window of the eye, critically refracts light and protects intraocular structures. Corneal pathologies, including trauma, infection, chemical injury, metabolic diseases, genetic conditions, and age-related degeneration, can lead to significant visual impairment. While penetrating keratoplasty or full-thickness corneal transplantation remains a standard and effective intervention for severe corneal dysfunction, limitations in donor tissue availability and the risk of immunogenic graft rejection necessitate alternative therapeutic strategies. Furthermore, for cases of isolated epithelial disfunction, a full-thickness cornea graft may not be required or effective. This review examines the potential of corneal epithelial constructs derived from autologous stem cells with functional barrier properties for corneal reconstruction and in vitro pharmacotoxicity testing. In this review, we delineate the current limitations of corneal transplantation, the advantages of stem cell-based approaches, and recent advances in generating engineered corneal epithelium. Finally, we address remaining technical challenges and propose future research directions aimed at clinical translation. Full article

Objectives: The aim was to present the complicated diagnostic and therapeutic process of atypical, painless keratitis caused by a cosmopolitan protozoan of the genus Acanthamoeba. Methods: This Case Report describes a medical case involving a 48-year-old woman who occasionally wears soft contact lenses and was referred to our hospital for treatment due to deteriorating visual acuity in her left eye. The diagnostic process included the isolation of amoebae from corneal scrapings and the morphological and molecular identification of the etiological agent of the infection. Results: After examination, painless atypical keratitis was diagnosed, initially considered recurrent herpetic keratitis. However, antiviral treatment did not bring about any improvement. Further observation revealed a dense, central, annular infiltrate on the periphery of the cornea. Despite treatment, the corneal infiltrate did not improve and the patient required therapeutic penetrating keratoplasty. Ultimately, the patient underwent combined surgery: corneal transplantation with cataract phacoemulsification and intraocular lens implantation. The postoperative course was uneventful. Conclusions: Acanthamoeba keratitis should be included in the differential diagnosis of keratitis, even in the absence of its characteristic feature of severe ocular pain, especially in contact lens wearers and patients who have had herpetic keratitis. Infection of the cornea with the Herpes simplex type 1 virus causes nerve degeneration, which probably translates into a painless course of Acanthamoeba castellanii infection. Full article

Background: Textural interface opacities (TIOs) following Descemet’s stripping automated endothelial keratoplasty (DSAEK) have become a significant postoperative concern. Studies have explored possible links such as stromal irregularities and viscoelastic usage, but the exact cause of TIOs remains unclear. PURPOSE: To evaluate the relationship between microkeratome dissection parameters and the development of textural interface opacities in DSAEK grafts utilizing the “M-TIO” grading scale for standardized assessment. Methods: Optical coherence tomography (OCT) images of DSAEK-processed corneal grafts, prepared with the same microkeratome and technique for transplantation at Bascom Palmer Eye Institute, underwent blinded analysis using a newly developed grading scale termed “M-TIO”. This analysis aimed to evaluate and categorize the occurrence of TIO, explore its potential correlation with graft characteristics prior to DSAEK preparation, and assess specific stages of the DSAEK dissection process. Data collected included the size of the microkeratome head used, the difference between the head and the actual stromal cut, and the difference between the pre-cut graft thickness and post-cut DSAEK lenticule thickness. Results: The study retrospectively included 422 donor corneas transplanted from 2019 to 2023. Variables associated with TIO in the final multivariable ordinal logistic model included the difference between the pre-cut graft thickness and the post-cut DSAEK lenticule thickness (OR: 1.57 [99% CI: 1.22 to 2.06] per 50 µm) and microkeratome head (OR: 6.95 [99% CI: 1.04 to 36.60] 300 µm, OR: 4.39 [99% CI: 0.76 to 19.00] 350 µm, and OR: 18.86 [99% CI: 2.35 to 175.91] 400 µm vs 450 or 500 µm, respectively). Conclusions: This study identified a statistically significant association between TIOs and the microkeratome DSAEK preparation, proposing several factors that could help prevent its occurrence. Specifically, creating an ultra-thin DSAEK lenticule from an initially thick graft using a smaller microkeratome head with the slow single-pass technique may increase the risk of TIOs. In contrast, utilizing a larger microkeratome head can improve stromal thickness consistency, reduce technical challenges during graft preparation, and lower the risk of TIOs. Full article

Background/Objectives: In this study, a mouse model of sutured endothelial keratoplasty was established and compared with a traditional penetrating keratoplasty (PKP) model in both syngeneic (BALB/c) and allogeneic (C57/BL6) patterns. Methods: For the endothelial keratoplasty (EK) model, chimeric donor tissues consisting of BALB/c epithelium-stroma combined with either syngeneic (BALB/c) or allogeneic (C57/BL6) stroma-endothelium were transplanted into BALB/c mice. Graft transparency, gene expression, and mRNA levels in the transplanted tissues were assessed using polymerase chain reaction (PCR) and quantitative real-time reverse transcription PCR (qRT-PCR) to evaluate inflammatory status. Results: Allogeneic PKP had a higher opacity score than syngeneic PKP. In contrast, syngeneic EK mice had similar opacity scores to those of allogeneic EK mice. Upregulation of CXCR3, the receptor for CXCL10, was demonstrated by qRT-PCR in allogeneic PKP mice but not in allogeneic EK mice. Conclusions: Comparison between the syngeneic and allogeneic PKP groups revealed differences in CXCR3 mRNA expression, suggesting that CXCR3 could be a potential biomarker for rejection in the PKP mouse model. Additionally, the EK model did not show CXCR3 upregulation despite the opaque cornea due to nonspecific inflammation. Therefore, our mouse model was considered to be a successfully established EK model. Full article

Objectives: A Ziemer LDV Z8 femtosecond laser (FSL) was used to obtain optimal cutting parameters with precise settings for donor and recipient preparations for Bowman layer transplantation. Methods: Of 48 human research corneas examined, 32 were used for Bowman layer preparation (donor) and 16 for pocket preparation (recipient) using the LDV Z8 FSL. The cutting thickness of the Bowman layer, pocket depth, and corresponding laser settings were varied. The quality of sections was evaluated based on the occurrence of adhesions, bridges, or perforations. Histological specimens were prepared and analyzed. Results: Preparation of the Bowman layer and recipient pocket was possible using all selected settings. The thinner the Bowman layer and the more superficial the pocket preparation, the higher the risk of perforation was. Considering the fact that the Bowman layer was cut as thinly as possible, a Bowman layer thickness of 30 µm showed a 100% success rate. Bowman layers cut at 25 µm had a lower success rate (50%). The pocket depth of 150 µm showed a 100% success rate in the preparation. Histological processing revealed smooth, precisely cut edges of Bowman layers and pockets. Implantation into the pocket was successful in all cases. Conclusions: Both Bowman layer and pocket preparation were technically and surgically feasible using the LDV Z8 FSL, and the prepared Bowman layers were thinner than those reported in previous studies. The optimal Bowman layer thickness was 30 µm, and a resection depth of 150 µm was used to prepare the pockets safely. Full article

Worldwide, millions of people suffer from visual impairments, ranging from partial to total blindness, with far-reaching consequences on personal, societal, and governmental levels. Corneal-related issues are among the leading causes of blindness, with corneal transplantation (keratoplasty) being the primary treatment. However, the demand for donor tissues far exceeds supply. The rise of printing technologies marks a revolution in tissue engineering, with 3D bioprinting at the forefront of developing innovative tissue repair and replacement solutions. The cornea emerges as an ideal candidate for this technology due to its distinct layers (epithelium, stroma, and endothelium). From a materials engineering standpoint, these layers resemble a hydrogel structure that facilitates fabrication. This review explores advancements in 3D bioprinting, focusing on the methodologies developed for corneal tissue engineering. It highlights design and construction aspects, including biomechanical and biocompatibility properties essential for creating synthetic implants and corneal scaffolds through bioprinting. Additionally, the review discusses the challenges and opportunities that could further drive innovation in tissue engineering. Full article

Background and Objectives: Descemet stripping automated endothelial keratoplasty (DSAEK) is a widely used surgical technique for treating corneal endothelial dysfunctions such as Fuchs endothelial corneal dystrophy (FECD) and pseudophakic bullous keratopathy (PBK). This study aimed to investigate the association between postoperative visual acuity and various corneal morphological and optical parameters, including corneal densitometry (CD) and higher-order aberrations (HOAs), measured using the Pentacam (OCULUS Optikgeräte GmbH, Wetzlar, Germany), as well as graft thickness, which was assessed by anterior segment optic coherence tomography (AS-OCT), (Optovue Inc., Fremont, CA, USA), and corneal thickness, assessed by both AS-OCT and Pentacam. Materials and Methods: This prospective, observational cohort study included 17 eyes from 13 patients who underwent DSAEK. Data on preoperative visual acuity were collected, while postoperative parameters were assessed during follow-up visits. Corneal measurements included the total corneal and corneal graft thickness, corneal densitometry in 20 defined subregions, and corneal higher-order aberrations. Associations between these parameters and postoperative visual acuity were evaluated using nonparametric statistical tests. Results: The postoperative visual acuity improved significantly (p < 0.001). Strong correlations were found between poorer visual acuity and higher CD values. The strongest correlations with visual acuity were found for CD 2–6 mm total (Rho = 0.795; p < 0.001), CD central 2–6 mm (Rho = 0.791; p < 0.001), and CD central 0–2 mm (Rho = 0.730; p < 0.001). Significant associations were also observed with anterior and posterior HOAs (Rho = 0.624, p = 0.01; and Rho = 0.556, p = 0.02, respectively). No correlation was found between visual outcomes and graft thickness measured by AS-OCT (Rho = 0.051; p = 0.85), nor with total corneal thickness measured by AS-OCT (Rho = −0.227; p = 0.38) or Pentacam (Rho = −0.369; p = 0.14). Conclusions: This study demonstrates that CD and HOAs are more strongly associated with postoperative visual acuity after DSAEK than traditionally monitored parameters such as graft or corneal thickness. The results highlight the value of detailed corneal imaging and support the use of advanced optical diagnostics in postoperative evaluation. Full article

Background: Textural Interface Opacities (TIOs) following Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) have become a notable postoperative concern. Several studies have attempted to identify associations between TIO development and intraoperative factors, including fluid dynamics, irregular stromal surfaces, viscoelastic usage, and recipient immunological responses. Despite these efforts, the precise etiology of TIO remains uncertain. TIO has not been considered predictable in the preoperative setting. Its detection has relied exclusively on slit-lamp biomicroscopy, a subjective approach lacking standardized diagnostic criteria, which limits diagnostic reliability and is highly susceptible to interobserver variability. Methods: Optical Coherence Tomography (OCT) images of DSAEK-processed corneal grafts, prepared using the same microkeratome and technique for transplantation at the Bascom Palmer Eye Institute, underwent blinded analysis using a newly developed grading scale termed “M-TIO”. This analysis focused on DSAEK-processed grafts OCT images to evaluate and categorize the occurrence of TIO and assess the final visual acuity of the patients at the 1-year postoperative evaluation. Results: Based on the results, the M-TIO grading scale demonstrated strong predictive value, with higher grades on OCT of DSAEK lenticules consistently associated with worse postoperative visual acuity. The study included 221 donor corneas transplanted from 2019 to 2023. Greater TIO based on the “M-TIO” grading scale was associated with worse recipient logMAR VA (Mean 0.151 [99% CI: 0.077 to 0.225] for corneas with no TIO, increased to 0.680 [99% CI: 0.532 to 0.828] for corneas with the greatest TIO grade). These findings highlight the clinical utility of the M-TIO scale as an objective and reliable preoperative tool for assessing graft quality and predicting postoperative visual outcomes. Conclusions: This study introduces the “M-TIO” grading scale, which provides a standardized and objective method for evaluating Textural Interface Opacities in DSAEK grafts prior to transplantation. Our results demonstrate a clear association between the severity of TIO as graded by the M-TIO scale, and postoperative visual outcomes, with higher TIO grades correlating with worse visual acuity, emphasizing its value in improving graft selection, and clinical decision-making in DSAEK. Full article

Recent research has highlighted the critical role of microbiota in organ transplant outcomes, particularly in the gut. However, the impact of ocular surface microbiota (OSM) on corneal transplantation remains largely unexplored. This piece examines the potential connection between OSM imbalances and corneal graftoutcomes, suggesting that microbial shifts could influence immune responses and transplant success. The OSM, though characterized by low microbial density, plays a critical role in local immune modulation and ocular surface homeostasis. Dysbiosis in this microbiota may compromise the immune privilege of the cornea, potentially increasing the risk of graft rejection. Looking at gut microbiota studies, where dysbiosis has been linked to graft failure, it is reasonable to hypothesize that similar mechanisms might be at play on the ocular surface. Disruptions in cornea’s immune tolerance pathways, such as anterior chamber-associated immune deviation (ACAID), may lead to pro-inflammatory responses that threaten graft survival. In addition, ocular surface diseases such as dry eye disease, microbial keratitis, and allergic conjunctivitis, already associated with OSM dysbiosis, may further exacerbate post-transplant complications. Despite the lack of direct studies linking OSM to corneal transplant outcomes, this opinion piece highlights the necessity for future research. Standardizing microbiota analysis methodologies and exploring therapeutic interventions, such as ocular probiotics, could open new roads for improving corneal transplant success and patient prognosis. Full article

Corneal transplantation remains a critical treatment option for individuals with corneal disorders, but it faces challenges such as rejection, high associated medical costs, and donor scarcity. A promising alternative for corneal replacement involves fabricating artificial cornea from a patient’s own cells. Our study aimed to leverage bioprinting to develop a corneal model using human corneal stromal cells embedded in a collagen-based bioink. We generated both cellular and acellular collagen I (COL I) constructs. Cellular constructs were cultured for up to 4 weeks, and gene expression analysis was performed to assess extracellular matrix (ECM) remodeling and fibrotic markers. Our results demonstrated a significant decrease in the expression of COL I, collagen III (COL III), vimentin (VIM), and vinculin (VCL), indicating a dynamic remodeling process towards a more physiologically relevant corneal ECM. Overall, our study provides a foundational framework for developing customizable, corneal replacements using bioprinting technology. Further research is necessary to optimize the bioink composition and evaluate the functional and biomechanical properties of these bioengineered corneas. Full article

Background and Objectives: The cornea protects the eye from external influences and contributes to its refractive power. Corneas belong to the most frequently transplanted tissues, providing a last resort for preserving the patient’s vision. There is a high demand for donor corneas worldwide, but almost 4% of these transplants are not eligible due to microbial contamination. The objective of this study is to ascertain the suitability of 222 nm Far-UVC irradiation for the decontamination of corneas without damaging corneal endothelial cells. Materials and Methods: To assess the destructive effect of irradiation and, thus, identify the applicable dose needed to decontaminate the cornea without interfering with its integrity, 141 porcine corneas were irradiated with 0, 60 or 150 mJ/cm² at 222 nm. In the second step, a series of 13 human corneas were subjected to half-sided irradiation using 15 or 60 mJ/cm² at 222 nm. After five days of in vitro culturing, the endothelial cell density of the non-irradiated area of each human cornea was compared to the irradiated area. Results: Irradiation with up to 60 mJ/cm² had no detectably significant effect on the cell integrity of human corneas (p = 0.764), with only a minimal reduction in cell density of 3.7% observed. These findings were partially corroborated by tests on porcine corneas, wherein the variability between test groups was consistent, even at increased irradiation doses of up to 150 mJ/cm², and no notable effects on the irradiated porcine endothelium were monitored. The efficacy of the antimicrobial treatment was evident in the disinfection tests conducted on corneas. Conclusions: These initial irradiation experiments demonstrated that 222 nm Far-UVC radiation has the potential to decontaminate the cornea without compromising sensitive endothelial cell viability. Full article

Background: Managing post-keratoplasty astigmatism remains challenging. Even though graft viability is the main concern in keratoplasty, astigmatism might hinder vision recovery following a successful corneal transplant. Photorefractive keratectomy (PRK) and topography-guided PRK may be options for correcting refractive errors in patients who underwent keratoplasty. The aim of the study was to compare the results of PRK and topography-guided PRK in patients who had undergone corneal keratoplasty. Methods: This study was conducted at the Chair and Ophthalmology Clinic of the Medical University of Silesia, at the Railway Hospital Katowice, from 2023 to 2024. Patients who underwent penetrating keratoplasty due to keratoconus or corneal scar (post-traumatic and post-inflammatory) with a residual spherical myopic or mixed myopic astigmatic refractive defect were included in this study. The studied patients were divided into two groups: 15 patients underwent PRK and 15 patients underwent topography-guided PRK. Each participant underwent a preoperative examination, including uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA) measured on the Snellen chart (LCD panel for visual acuity testing Frey CP-400, Optotech Medical, Niepołomnice, Niepołomice, Poland), cycloplegic refraction, corneal pachymetry and topography (Schwind Sirius+, Pentacam), wavefront aberrations (Schwind Peramis, Pentacam), applanation tonometry, and anterior and posterior segment examinations, conducted at baseline and 1, 3, 6, and 12 months. Results: Keratoconus was the most common reason for keratoplasty (80% vs. 60%). Following PRK, the mean KI in group (1) decreased significantly to 43.88 ± 3.64 (p < 0.001), and in the group (2), the mean diopters decreased significantly after the intervention to 46.46 ± 2.80 (p < 0.001). The mean spherical refractive error in group (2) changed significantly after the intervention, reaching −2.72 ± 1.28 D (p < 0.001). The mean cylinder in group (1) changed significantly after PRK to have a mean of −2.75 ± 1.44 D (p < 0.001). Also, in group (2), it changed significantly after the intervention to have a mean of −2.95 ± 1.99 D (p < 0.001). There was a significant increase in both uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) after topography-guided PRK at all the follow-up points of 1, 3, 6, and 12 months (p < 0.001). The mean higher-order corneal aberrations (HOAs) after topography-guided PRK were 1.33 ± 0.50, ranging from 0.22 to 2.34 (p < 0.001). Conclusions: Topography-guided PRK is safer and more effective in correcting aberrations and refractive errors after corneal keratoplasty than regular PRK. Additionally, topography-guided PRK reduces high-order aberrations by utilizing advanced topographic mapping of the cornea, enabling precise customization of the treatment to address individual corneal surface irregularities. Full article

The World Health Organization estimates that approximately 285 million people suffer from visual impairments, around 5% of which are caused by corneal pathologies. Currently, the most common clinical treatment consists of a corneal transplant (keratoplasty) from a human donor. However, worldwide demand for donor corneas amply exceeds the available supply. Lamellar keratoplasty (transplantation replacement of only one of the three layers of the cornea) is partially solving the problem of cornea undersupply. Obviously, cell therapy applied to every one of these layers will expand current therapeutic options, reducing the cost of ophthalmological interventions and increasing the effectiveness of surgery. Mesenchymal stem cells (MSCs) are adult stem cells with the capacity for self-renewal and differentiation into different cell lineages. They can be obtained from many human tissues, such as bone marrow, umbilical cord, adipose tissue, dental pulp, skin, and cornea. Their ease of collection and advantages over embryonic stem cells or induced pluripotent stem cells make them a very practical source for experimental and potential clinical applications. In this review, we focus on recent advances using MSCs from different sources to replace the damaged cells of the three corneal layers, at both the preclinical and clinical levels for specific corneal diseases. Full article

Purpose: To evaluate visual acuity improvement and identify contributing factors in patients with severe keratitis affecting both virgin and transplanted corneas, treated at a hospital. Methods: A retrospective analysis was conducted on 497 patients with unilateral corneal ulcers treated at a tertiary referral center between 2008 and 2023. Data included distance (BCVA) and near best-corrected visual acuity at initial presentation and at discharge, treatments before hospital admission, demographic details, risk factors, clinical signs and symptoms, ancillary test results, and management strategies. Patients were categorized into two groups: Group A (naïve corneal ulcers, 379 patients) and Group B (post-keratoplasty infectious keratitis, 118 patients). Additional analysis focused on patients with presenting visual acuity of at least 1.0 logMAR (≤5/50 Snellen charts = legal blindness) to predict final visual outcomes. Results: The median BCVA at presentation for the entire cohort was 1.9 logMAR, advancing to 1.5 logMAR at discharge (p < 0.001). At least one line improvement in BCVA was observed in 47% of patients (52% of naïve cornea and 33% of transplanted cornea patients). Significantly worse results were observed in Group B were observed for BCVA at presentation, BCVA improvement, and distance and near vision improvement. Among patients with legal blindness at presentation, vision status improved for 52/379 (14%) in Group A and 6/118 (5%) in Group B during hospital admission (p < 0.001), while 67% of the cohort was discharged with VA equal or worse than 5/50. The average hospital stay was 9 days. Near visual acuity got better in 23% of patients (27% in Group A vs. 9% in Group B). A multivariate regression model showed that older age and worse distance BCVA on admission were independent negative predictors of improvement (p < 0.001, p < 0.001, respectively) while midperiphery ulcers were associated with better visual outcomes. Conclusions: Hospital admission leads to BCVA improvement in 47% of the patients with severe corneal ulcer, though the prognosis is significantly worse for those with post-keratoplasty microbial keratitis. At discharge, 67% of patients remained at the legal blindness level. Older age and lower BCVA at first presentation are associated with worse prognosis, while ulcers located in the corneal midperiphery are linked to better visual outcomes. Full article