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A Tenon's capsule/bulbar conjunctiva interface biomimetic to model fibrosis and local drug delivery.PloS One 2020Glaucoma filtration surgery is one of the most effective methods for lowering intraocular pressure in glaucoma. The surgery efficiently reduces intra-ocular pressure but...
Glaucoma filtration surgery is one of the most effective methods for lowering intraocular pressure in glaucoma. The surgery efficiently reduces intra-ocular pressure but the most common cause of failure is scarring at the incision site. This occurs in the conjunctiva/Tenon's capsule layer overlying the scleral coat of the eye. Currently used antimetabolite treatments to prevent post-surgical scarring are non-selective and are associated with potentially blinding side effects. Developing new treatments to target scarring requires both a better understanding of wound healing and scarring in the conjunctiva, and new means of delivering anti-scarring drugs locally and sustainably. By combining plastic compression of collagen gels with a soft collagen-based layer, we have developed a physiologically relevant model of the sub-epithelial bulbar conjunctiva/Tenon's capsule interface, which allows a more holistic approach to the understanding of subconjunctival tissue behaviour and local drug delivery. The biomimetic tissue hosts both primary human conjunctival fibroblasts and an immune component in the form of macrophages, morphologically and structurally mimicking the mechanical proprieties and contraction kinetics of ex vivo porcine conjunctiva. We show that our model is suitable for the screening of drugs targeting scarring and/or inflammation, and amenable to the study of local drug delivery devices that can be inserted in between the two layers of the biomimetic. We propose that this multicellular-bilayer engineered tissue will be useful to study complex biological aspects of scarring and fibrosis, including the role of inflammation, with potentially significant implications for the management of scarring following glaucoma filtration surgery and other anterior ocular segment scarring conditions. Crucially, it uniquely allows the evaluation of new means of local drug delivery within a physiologically relevant tissue mimetic, mimicking intraoperative drug delivery in vivo.
Topics: Animals; Biomimetic Materials; Biomimetics; Cell Line; Cicatrix; Conjunctiva; Drug Delivery Systems; Drug Evaluation, Preclinical; Feasibility Studies; Fibroblasts; Fibrosis; Filtering Surgery; Glaucoma; Humans; Intraoperative Care; Monocytes; Postoperative Complications; Primary Cell Culture; Swine; Tenon Capsule; Wound Healing
PubMed: 33141875
DOI: 10.1371/journal.pone.0241569 -
The Indian Journal of Medical Research Nov 2020
Topics: Child; Conjunctiva; Developmental Disabilities; Humans; Vascular Diseases; Veins
PubMed: 35345148
DOI: 10.4103/ijmr.IJMR_2167_19 -
International Journal of Molecular... Apr 2023The porcine ocular surface is used as a model of the human ocular surface; however, a detailed characterization of the porcine ocular surface has not been documented....
The porcine ocular surface is used as a model of the human ocular surface; however, a detailed characterization of the porcine ocular surface has not been documented. This is due, in part, to the scarcity of antibodies produced specifically against the porcine ocular surface cell types or structures. We performed a histological and immunohistochemical investigation on frozen and formalin-fixed, paraffin-embedded ocular surface tissue from domestic pigs using a panel of 41 different antibodies related to epithelial progenitor/differentiation phenotypes, extracellular matrix and associated molecules, and various niche cell types. Our observations suggested that the Bowman's layer is not evident in the cornea; the deep invaginations of the limbal epithelium in the limbal zone are analogous to the limbal interpalisade crypts of human limbal tissue; and the presence of goblet cells in the bulbar conjunctiva. Immunohistochemistry analysis revealed that the epithelial progenitor markers cytokeratin (CK)15, CK14, p63α, and P-cadherin were expressed in both the limbal and conjunctival basal epithelium, whereas the basal cells of the limbal and conjunctival epithelium did not stain for CK3, CK12, E-cadherin, and CK13. Antibodies detecting marker proteins related to the extracellular matrix (collagen IV, Tenascin-C), cell-matrix adhesion (β-dystroglycan, integrin α3 and α6), mesenchymal cells (vimentin, CD90, CD44), neurons (neurofilament), immune cells (HLA-ABC; HLA-DR, CD1, CD4, CD14), vasculature (von Willebrand factor), and melanocytes (SRY-homeobox-10, human melanoma black-45, Tyrosinase) on the normal human ocular surface demonstrated similar immunoreactivity on the normal porcine ocular surface. Only a few antibodies (directed against N-cadherin, fibronectin, agrin, laminin α3 and α5, melan-A) appeared unreactive on porcine tissues. Our findings characterize the main immunohistochemical properties of the porcine ocular surface and provide a morphological and immunohistochemical basis useful to research using porcine models. Furthermore, the analyzed porcine ocular structures are similar to those of humans, confirming the potential usefulness of pig eyes to study ocular surface physiology and pathophysiology.
Topics: Swine; Humans; Animals; Limbus Corneae; Cornea; Conjunctiva; Extracellular Matrix; Sus scrofa; Epithelial Cells
PubMed: 37108705
DOI: 10.3390/ijms24087543 -
JAMA Ophthalmology Oct 2017Lissamine green (LG) staining of the conjunctiva is a key biomarker in evaluating ocular surface disease. The disease currently is assessed using relatively coarse...
IMPORTANCE
Lissamine green (LG) staining of the conjunctiva is a key biomarker in evaluating ocular surface disease. The disease currently is assessed using relatively coarse subjective scales. Objective assessment would standardize comparisons over time and between clinicians.
OBJECTIVE
To develop a semiautomated, quantitative system to assess lissamine green staining of the bulbar conjunctiva on digital images.
DESIGN, SETTING, AND PARTICIPANTS
Using a standard photography protocol, 35 digital images of the conjunctiva of 11 patients with a diagnosis of dry eye disease based on characteristic signs and symptoms were obtained after topical administration of preservative-free LG, 1%, solution. Images were scored independently by 2 masked ophthalmologists in an academic medical center using the van Bijsterveld and National Eye Institute (NEI) scales. The region of interest was identified by manually marking 7 anatomic landmarks on the images. An objective measure was developed by segmenting the images, forming a vector of key attributes, and then performing a random forest regression. Subjective scores were correlated with the output from a computer algorithm using a cross-validation technique. The ranking of images from least to most staining was compared between the algorithm and the ophthalmologists. The study was conducted from April 26, 2012, through June 2, 2016.
MAIN OUTCOMES AND MEASURES
Correlation and level of agreement among computerized algorithm scores, van Bijsterveld scale clinical scores, and NEI scale clinical scores.
RESULTS
The scores from the automated algorithm correlated well with the mean scores obtained from the gradings of 2 ophthalmologists for the 35 images using the van Bijsterveld scale (Spearman correlation coefficient, rs = 0.79), and moderately with the NEI scale (rs = 0.61) scores. For qualitative ranking of staining, the correlation between the automated algorithm and the 2 ophthalmologists was rs = 0.78 and rs = 0.83.
CONCLUSIONS AND RELEVANCE
The algorithm performed well when evaluating LG staining of the conjunctiva, as evidenced by good correlation with subjective gradings using 2 different grading scales. Future longitudinal studies are needed to assess the responsiveness of the algorithm to change of conjunctival staining over time.
Topics: Administration, Topical; Aged; Algorithms; Cohort Studies; Coloring Agents; Conjunctiva; Diagnostic Techniques, Ophthalmological; Dry Eye Syndromes; Female; Humans; Image Processing, Computer-Assisted; Lissamine Green Dyes; Male; Middle Aged; Observer Variation; Photography; Reproducibility of Results; Staining and Labeling
PubMed: 28910455
DOI: 10.1001/jamaophthalmol.2017.3346 -
Experimental Eye Research Dec 2020Most patients with chronic dry eye disease (DED) have episodic flares, which can be triggered by a variety of activities and environmental stresses. These flares are... (Review)
Review
Most patients with chronic dry eye disease (DED) have episodic flares, which can be triggered by a variety of activities and environmental stresses. These flares are typically associated with rapid exacerbation of discomfort symptoms, followed by prolonged elevation of inflammation. In an acute flare, ocular surface inflammation begins with a nonspecific innate immune response, in some cases followed by a slower but more specific adaptive immune response. At the ocular surface, epithelial cells are central to the innate immune response, and we discuss their role in DED flares alongside the other core components. Epithelial cells and other cells of the innate response (neutrophils, monocytes, macrophages and dendritic cells) trigger flares in response to increased osmolarity, detected via pattern receptors on their cell surface. Ultimately, downstream signaling pathways activate innate and adaptive immune responses, with consequent inflammation and symptoms. In chronic DED, pathogenic T cells have infiltrated the ocular surface tissues. The established adaptive immune response is likely to lead to flare-ups at lower thresholds of stress, with inflammation maintained over a longer period. Increased understanding of the inflammatory cascades activated during a flare may guide management and improve outcomes.
Topics: Conjunctiva; Cytokines; Dry Eye Syndromes; Humans; Immunity, Innate; Inflammation; T-Lymphocytes
PubMed: 33039458
DOI: 10.1016/j.exer.2020.108294 -
Viruses Aug 2021Human papillomaviruses (HPV) are a large group of DNA viruses that infect the basal cells of the stratified epithelium at different anatomic locations. In the ocular... (Review)
Review
Human papillomaviruses (HPV) are a large group of DNA viruses that infect the basal cells of the stratified epithelium at different anatomic locations. In the ocular adnexal region, the mucosa of the conjunctiva and the lacrimal drainage system, as well as the eyelid skin, are potential locations for HPV-related neoplasia. The role of HPV in squamous cell neoplasia of the ocular adnexa has been debated for several decades. Due to the rarity of all these tumors, large studies are not available in the scientific literature, thereby hampering the precision of the HPV prevalence estimates and the ability to conclude. Nevertheless, increasing evidence supports that defined subsets of conjunctival papillomas, intraepithelial neoplasia, and carcinomas develop in an HPV-dependent pathway. The role of HPV in squamous cell tumors arising in the lacrimal drainage system and the eyelid is still uncertain. Further, the potential of HPV status as a diagnostic, prognostic, or predictive biomarker in these diseases is a topic for future research.
Topics: Carcinoma in Situ; Carcinoma, Squamous Cell; Conjunctiva; Humans; Lacrimal Apparatus; Papillomaviridae; Papillomavirus Infections
PubMed: 34452388
DOI: 10.3390/v13081522 -
The Ocular Surface Apr 2020The conjunctiva is a goblet cell rich mucosal tissue. Goblet cells are supported by tear growth factors and IL-13 produced by resident immune cells. Goblet cell... (Review)
Review
The conjunctiva is a goblet cell rich mucosal tissue. Goblet cells are supported by tear growth factors and IL-13 produced by resident immune cells. Goblet cell secretions are essential for maintaining tear stability and ocular surface homeostasis. In addition to producing tear stabilizing mucins, they also produce cytokines and retinoic acid that condition monocyte-derived phagocytic cells in the conjunctiva. Aqueous tear deficiency from lacrimal gland disease and systemic inflammatory conditions results in goblet cell loss that amplifies dry eye severity. Reduced goblet cell density is correlated with more severe conjunctival disease, increased IFN-γ expression and antigen presenting cell maturation. Sterile Alpha Motif (SAM) pointed domain epithelial specific transcription factor (Spdef) gene deficient mice that lack goblet cells have increased infiltration of monocytes and dendritic cells with greater IL-12 expression in the conjunctiva. Similar findings were observed in the conjunctiva of aged mice. Reduced retinoic acid receptor (RXRα) signaling also increases conjunctival monocyte infiltration, IFN-γ expression and goblet cell loss. Evidence suggests that dry eye therapies that suppress IFN-γ expression preserve conjunctival goblet cell number and function and should be considered in aqueous deficiency.
Topics: Animals; Cell Communication; Conjunctiva; Dry Eye Syndromes; Goblet Cells; Mice, Knockout; Tears
PubMed: 31953222
DOI: 10.1016/j.jtos.2019.12.006 -
Experimental Eye Research Aug 2016Multispectral imaging (MSI) is a well-established technique for non-invasive oximetry of retinal blood vessels, which has contributed to the understanding of a variety...
Multispectral imaging (MSI) is a well-established technique for non-invasive oximetry of retinal blood vessels, which has contributed to the understanding of a variety of retinal conditions, including glaucoma, diabetes, vessel occlusion, and retinal auto-regulation. We report the first study to use snapshot multi-spectral imaging (SMSI) for oximetry of the bulbar conjunctival and episcleral microvasculature in the anterior segment of the eye. We report the oxygen dynamics of the bulbar conjunctival and episcleral microvasculature at normoxia and at acute mild hypoxia conditions. A retinal-fundus camera fitted with a custom Image-Replicating Imaging Spectrometer was used to image the bulbar conjunctival and episcleral microvasculature in ten healthy human subjects at normoxia (21% Fraction of Inspired Oxygen [FiO2]) and acute mild hypoxia (15% FiO2) conditions. Eyelid closure was used to control oxygen diffusion between ambient air and the sclera surface. Four subjects were imaged for 30 seconds immediately following eyelid opening. Vessel diameter and Optical Density Ratio (ODR: a direct proxy for oxygen saturation) of vessels was computed automatically. Oximetry capability was validated using a simple phantom that mimicked the scleral vasculature. Acute mild hypoxia resulted in a decrease in blood oxygen saturation (SO2) (i.e. an increase in ODR) when compared with normoxia in both bulbar conjunctival (p < 0.001) and episcleral vessels (p = 0.03). Average episcleral diameter increased from 78.9 ± 8.7 μm (mean ± standard deviation) at normoxia to 97.6 ± 14.3 μm at hypoxia (p = 0.02). Diameters of bulbar conjunctival vessels showed no significant change from 80.1 ± 7.6 μm at normoxia to 80.6 ± 7.0 μm at hypoxia (p = 0.89). When exposed to ambient air, hypoxic bulbar conjunctival vessels rapidly reoxygenated due to oxygen diffusion from ambient air. Reoxygenation occured in an exponential manner, and SO2 reached normoxia baseline levels. The average ½ time to full reoxygenation was 3.4 ± 1.4 s. As a consequence of oxygen diffusion, bulbar conjunctival vessels will be highly oxygenated (i.e. close to 100% SO2) when exposed to ambient air. Episcleral vessels were not observed to undergo any significant oxygen diffusion, instead behaving similarly to pulse oximetry measurements. This is the first study to the image oxygen dynamics of bulbar conjunctival and episcleral microvasculature, and consequently, the first study to directly observe the rapid reoxygenation of hypoxic bulbar conjunctival vessels when exposed to ambient air. Oximetry of bulbar conjunctival vessels could potentially provide insight into conditions where oxygen dynamics of the microvasculature are not fully understood, such as diabetes, sickle-cell diseases, and dry-eye syndrome. Oximetry in the bulbar conjunctival and episcleral microvasculature could be complimentary or alternative to retinal oximetry.
Topics: Adult; Conjunctiva; Diagnostic Techniques, Ophthalmological; Equipment Design; Female; Healthy Volunteers; Humans; Male; Microvessels; Oximetry; Oxygen Consumption; Regional Blood Flow; Sclera
PubMed: 27317046
DOI: 10.1016/j.exer.2016.06.008 -
Indian Journal of Ophthalmology Feb 2018A careful examination of cornea and ocular surface eliciting the basic signs will help a clinician toward an accurate diagnosis. Flipping the upper lid or pulling the... (Review)
Review
A careful examination of cornea and ocular surface eliciting the basic signs will help a clinician toward an accurate diagnosis. Flipping the upper lid or pulling the lower lid to look at the inferior fornix may help to pick up any subtle clinical sign. Meticulous documentation by diffuse and slit view will help in following up the disease. Eyelids and ocular surface are evaluated externally and by slit lamp. Slit-lamp examination with the use of the stains such as fluorescein, rose bengal, or lissamine green provides extensive knowledge about the ocular surface. Tests of tear production are also detailed herein. This review is intended to help the eye practitioners in eliciting common clinical signs seen in cornea and ocular surface diseases.
Topics: Conjunctiva; Cornea; Corneal Diseases; Corneal Topography; Humans; Staining and Labeling; Tears; Tomography, Optical Coherence
PubMed: 29380758
DOI: 10.4103/ijo.IJO_716_17 -
Korean Journal of Ophthalmology : KJO Jun 2019
Topics: Biopsy; Conjunctiva; Conjunctival Neoplasms; Diagnosis, Differential; Humans; Magnetic Resonance Imaging; Male; Neurilemmoma; Ophthalmologic Surgical Procedures; Young Adult
PubMed: 31179662
DOI: 10.3341/kjo.2018.0082