Search Results (362)

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

Radiation-induced keratoconjunctivitis sicca (KCS) is a significant late complication in dogs receiving radiation therapy for intranasal tumors, particularly with hypofractionated intensity-modulated radiation therapy (IMRT). This retrospective case-control study was performed to identify anatomical and dosimetric risk factors for KCS in 15 canine patients treated with IMRT delivered in 4–6 weekly fractions of 8 Gy. Orbital structures were retrospectively contoured, and dose–volume metrics (D50) were calculated. Receiver operating characteristic (ROC) curve analysis and odds ratios were used to evaluate the associations between radiation dose and KCS development. Six dogs (33%) developed KCS within three months post-treatment. Statistically significant dose differences were observed between affected and unaffected eyes for the eyeball, cornea, and retina. ROC analyses identified dose thresholds predictive of KCS: 13.8 Gy (eyeball), 14.9 Gy (cornea), and 17.0 Gy (retina), with the retina showing the highest odds ratio (28.33). To ensure clinical relevance, KCS was diagnosed based on decreased tear production combined with corneal damage to ensure clinical relevance. This study proposes dose thresholds for ocular structures that may guide treatment planning and reduce the risk of KCS in canine patients undergoing IMRT. Further prospective studies are warranted to validate these thresholds and explore mitigation strategies for high-risk cases. Full article

(1) Background: A decrease in corneal hydration during refractive surgery is observed clinically as well as in laboratory settings, but the associated consequences are not yet fully understood. The purpose of this paper is to analyze the impact of the gain of ablation efficiency due to hydration changes during cornea refractive surgery. (2) Methods: We developed a simulation model to evaluate the influence of hydration changes on the ablation algorithms used in laser refractive surgery. The model simulates different physical effects of an entire surgical process, simulating the shot-by-shot ablation process based on a modeled beam profile. The model considers corneal hydration, as well as environmental humidity, along with the laser beam characteristics and ablative spot properties for evaluating any hydration changes and their effect on laser refractive surgery. (3) Results: Using pulse lists collected from actual treatments, we simulated the gain of efficiency during the ablation process. Ablation efficiency is increased due to dehydration effects during laser treatments. Longer treatments suffer larger dehydration effects and are more prone to overcorrections due to gain of efficiency than shorter treatments. (4) Conclusions: The improper use of a model that overestimates or underestimates the effects derived from the hydration dynamics during treatment may result in suboptimal refractive corrections. This model may contribute to improving emmetropization and the correction of ocular aberrations with improved laser parameters that can compensate for the changes in ablation efficiency due to hydration changes in the cornea. Full article

Background/Objectives: The transparency and biomechanical properties of the human cornea are governed by the precise organization of collagen fibers. A novel quantitative technique to analyze corneal collagen organization, based on intensity gradient modeling and probability density function (PDF) fitting, is proposed. Methods: Derived from second-harmonic generation (SHG) images, the method calculates image gradients, derives PDFs of gradient orientations, and fits them to Gaussian models. Results: Tested across species and temporal healing stages, this approach is an advantageous alternative to traditional methods like Fourier transform and structure tensor analyses, particularly in noisy or low-contrast conditions. Conclusions: The technique offers a scalable, robust framework suitable for research, clinical diagnostics, and treatment monitoring. Full article

Medical hydrogels represent a promising solution for the treatment of corneal diseases and trauma, offering potential to address the shortage of donor corneas. To meet the functional requirements of artificial corneas in tissue engineering, it is crucial to fabricate biomimetic structures with high optical transparency using 3D printing techniques. As fiber alignment during the printing process has a pronounced impact on light transmittance, precise control of the printing parameters is essential. This study focuses on the experimental optimization of 3D printing conditions for hydrogel materials to improve their physical properties, particularly optical clarity, thereby enhancing their suitability for artificial corneal applications. Collagen derived from bovine Achilles tendons was chosen due to its excellent printability. A series of controlled experiments were conducted to systematically investigate the influence of key process parameters on hydrogel transparency. The findings enabled the identification of an optimized parameter set that significantly improved the optical properties of the 3D-printed biomimetic corneal stroma. Additionally, cell seeding and culture assays confirmed the favorable biocompatibility of the developed material. 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 and Objectives: We have previously reported that omega-3 polyunsaturated fatty acids (PUFAs) derived from fish oil (FO) is an effective treatment for type 1 and type 2 diabetes neural and vascular complications. As omega-3 PUFAs become more widely used as a nutritional and disease modifying supplement an important question to be addressed is what is the preferred source of omega-3 PUFAs? Methods: Using a type 2 diabetic rat model and early and late intervention protocols we examined the effect of dietary treatment with omega-3 PUFAs derived from menhaden (fish) oil (MO), krill oil (KO), algal oils consisting primarily of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) or combination of EPA + DHA, or pharmaceutical-derived ethyl esters of EPA, DHA or combination of EPA + DHA. Nerve related endpoints included motor and sensory nerve conduction velocity, heat sensitivity of the hind paw, intraepidermal nerve density, cornea nerve fiber length, and cornea sensitivity. Vascular reactivity to acetylcholine and calcitonin gene-related peptide by epineurial arterioles that provide blood to the sciatic nerve was also examined. Results: The dose of each omega-3 PUFA supplement increased the content of EPA, docosapentaenoic acid (DPA), and/or DHA in red blood cell membranes, serum and liver. Diabetes caused a significant decrease of 30–50% of neural function and fiber occupancy of the skin and cornea and vascular reactivity. Treatment with MO, KO or the combination of EPA + DHA provided through algal oil or ethyl esters provided significant improvement of each neural endpoint and vascular function. Algal oil or ethyl ester of EPA alone was the least effective with algal oil or ethyl ester of DHA alone providing benefit that approached combination therapies for some endpoints. Conclusions: We confirm that omega-3 PUFAs are an effective treatment for DPN and sources other than fish oil are similarly effective. Full article

Background and Clinical Significance: Brittle cornea syndrome (BCS) is a rare, autosomal recessive connective tissue disorder characterized by extreme corneal thinning, high myopia, and increased risk of spontaneous or trauma-induced ocular rupture. It is primarily caused by mutations in the ZNF469 or PRDM5 genes, which regulate extracellular matrix integrity. Early recognition and diagnosis of BCS are crucial to prevent severe visual impairment. This report presents two genetically confirmed cases of BCS in Albanian siblings, emphasizing the diagnostic value of whole-exome sequencing and individualized surgical management strategies. Case Presentation: Two siblings—a 28-year-old male and a 25-year-old female—presented with progressive visual deterioration and marked corneal thinning (<200 µm). Both had a history of spontaneous ocular rupture following minor trauma in the contralateral eye. Detailed ophthalmologic evaluation revealed keratoglobus, high myopia, and irregular astigmatism. Genetic testing identified the homozygous pathogenic variant c.974delG (p.Cys325LeufsX2) in the PRDM5 gene in both cases. The male underwent penetrating keratoplasty (PKP), achieving a best-corrected visual acuity (BCVA) of 20/30. The female initially underwent deep anterior lamellar keratoplasty (DALK), which was converted to PKP intraoperatively due to central endothelial perforation, resulting in a BCVA of 20/25. Both patients remained complication-free over a 7-year follow-up period. Conclusions: These cases highlight the importance of early genetic diagnosis and a tailored surgical approach in managing BCS. Long-term monitoring and protective strategies are essential to prevent complications. Incorporating genetic testing into clinical practice can enhance diagnostic accuracy and guide personalized treatment plans in patients with hereditary corneal dystrophies. Full article

Acanthamoeba keratitis (AK) is a vision-threatening eye infection induced by the free-living species of the amoeba genus Acanthamoeba, presenting considerable therapeutic difficulties due to its frequently delayed diagnosis, chronic nature, and resistance to standard treatments. This review examines the changing landscape of AK, emphasizing recent developments in pathogenesis, diagnosis, and treatment. We examine the molecular pathways that enable Acanthamoeba invasion and persistence in the cornea, and how comprehending these processes can inform the creation of more effective treatment therapies. The review emphasizes current advancements in diagnostic methodologies, such as PCR-based tests and in vivo confocal imaging, which have enhanced early detection rates and diagnostic precision. Furthermore, we analyze contemporary treatment modalities, including antimicrobial therapy and surgical procedures, while recognizing the difficulties presented by antimicrobial resistance and the lack of standardized treatment protocols. This review seeks to deliver a thorough examination of AK, presenting insights into cutting-edge treatments and pinpointing essential areas for future research to address the persistent hurdles in controlling this potentially devastating ocular infection. 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

Nociceptors respond to noxious stimuli and transmit pain signals to the central nervous system. In the cornea, the nociceptors located in the most external layer provide a myriad of sensation modalities. Damage to these corneal nerve fibers can induce neuropathic pain. In response, corneal nerves become sensitized to previously non-noxious stimuli. Assessing corneal pain origin is a complex ophthalmic challenge due to variations in its causes and manifestations. Current FDA-approved therapies for corneal nociceptive pain, such as acetaminophen and NSAIDs, provide only broad-acting relief with unwanted side effects, highlighting the need for precision medicine for corneal nociceptive pain. A few targeted treatments, including perfluorohexyloctane (F6H8) eye drops and Optive Plus (TRPV1 antagonist), are FDA-approved, while others are in preclinical development. Treatments that target signaling pathways related to neurotrophic factors, such as nerve growth factors and ion channels, such as the transient receptor potential (TRP) family or tropomyosin receptor kinase A, may provide a potential combinatory therapeutic approach. This review describes the roles of nociceptors in corneal pain. In addition, it evaluates molecules within nociceptor signaling pathways for their potential to serve as targets for efficient therapeutic strategies for corneal nociceptive pain aimed at modulating neurotrophic factors and nociceptive channel sensitivity. Full article

Background/Objectives: Dry eye disease (DED) is a multifactorial inflammatory disease that disrupts the ocular surface, causing tear film instability, epithelial damage, and chronic inflammation. Mesenchymal stem cell-derived exosomes (MSC-exos) are promising therapeutics with immunomodulatory and regenerative properties. This study investigates the therapeutic effects of umbilical cord MSC-derived exosomes (UCMSC-exos) in a severe dry eye model, induced by a surgical resection of the infra-orbital (ILG) and extra-orbital lacrimal gland (ELG) in rats. Methods: Clinical evaluations, including tear volume measurement, slit lamp biomicroscopy, fluorescein staining, and spectral domain optical coherence tomography (SD-OCT), were performed to assess corneal neovascularization, corneal abrasion, and epithelial/stromal thickness. Histopathological analysis, immunohistochemistry, and mRNA gene expression were conducted to evaluate corneal tissue changes and inflammatory marker expression. Results: The results show that the treatment group exhibited significantly reduced corneal neovascularization compared to the control group (p = 0.030). During the first month, the Exo group also had a significantly lower corneal fluorescein staining area (p = 0.032), suggesting accelerated wound healing. SD-OCT analysis revealed that the corneal epithelial thickness in the treatment group was closer to normal levels compared to the control group (p = 0.02 and p = 0.006, respectively). UCMSC-exos treatment also modulated the expression of α-SMA and apoptosis in the cornea. Additionally, the gene expression of inflammatory cytokines (IL-1β and TNF-α) were downregulated. Conclusions: These findings suggest that MSC-exosome therapy offers a novel, cell-free regenerative approach for managing severe DED, modulating inflammatory response. Full article

The biomechanical and optical properties of the cornea are responsible for its functional response, structural integrity and refractive function. Corneal viscoelasticity is the cornea’s ability to absorb transient increases in intraocular pressure (IOP) and constitutes a biomarker of glaucoma. The use of silicone hydrogel soft contact lenses (SiH-SCLs) can affect both corneal viscoelasticity and IOP. However, the behavior of the pure elastic and viscous components remains hidden within viscoelastic properties, and their influence and relationship with IOP in the biomechanical changes observed with short-term SiH-SCL use remains unknown. This study investigates the effects of silicone hydrogel soft contact lenses (SiH-SCLs) on corneal elasticity and viscosity and their influence on IOP over different lens wear periods: 10 or 20 consecutive days. Ocular Response Analyzer (ORA) measurements were combined with a biomechanical Standard Linear Solid Model (SLSM) to differentiate and calculate the elastic and viscous components of the cornea. The results showed that after 10 days of lens wear, elasticity and viscosity increased, with a significant reduction in IOP. After 20 days, elasticity and viscosity decreased, with a further reduction in IOP, reflecting a time-dependent effect of SiH-SCLs on corneal biomechanics. The study indicates the potential protective role of corneal viscosity against changes in IOP, which may be used for glaucoma treatment. Full article

Objective: The aim of this study was to assess the safety and preliminary efficacy of repetitive magnetic stimulation (RMS) as a treatment intervention for dry eye disease (DED), focusing on symptom reduction. Methodology: This investigation involved 22 adult participants (85% females, aged between 22 and 79 years) diagnosed with moderate-to-severe DED. These individuals were subjected to RMS treatment targeting one or both eyes using the VIVEYE-Ocular Magnetic Neurostimulation System version 1.0 (Epitech-Mag LTD; National Institute of Health (NIH) clinical trials registry #NCT03012698). A placebo-controlled group was also included for comparative analysis, with all subjects being monitored over a three-month period. The evaluation of safety encompassed monitoring changes in best corrected visual acuity, ocular pathology, and the reporting of adverse events. Participant tolerance was gauged through questionnaires, measurements of intraocular pressure (IOP), Schirmer’s test, and vital signs. The efficacy of the treatment was assessed by comparing pre- and post-treatment scores for fluorescein staining (according to National Eye Institute (NEI) grading) and patient-reported outcomes. Results: No statistically significant changes were found in visual acuity, IOP, or Schirmer’s test results between the RMS-treated and control groups (p < 0.05), indicating that RMS does not negatively impact these ocular functions. However, RMS treatment was associated with improved tear film stability (p = 0.19 vs. p = 0.04) and corneal health (p = 0.52 vs. p = 0.004), with no improvements in the control group. Initial symptom improvement was observed in both RMS-treated and placebo groups (p = 0.007 vs. p = 0.008), suggesting a potential therapeutic benefit of RMS for ocular surface conditions beyond a placebo effect. Conclusions: This study presents RMS as a promising therapeutic approach for DED, highlighting its potential to promote corneal epithelial repair, enhance tear film stability, and improve patient-reported symptoms without negatively impacting IOP, visual acuity, or tear production. This confirms the safety and suggests the efficacy of RMS therapy for dry eye conditions. Full article