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Eye and Vision (London, England) Apr 2021Symptoms of dryness discomfort in soft contact lens wearers frequently lead to discontinuation from wear. The negative influence of pre-fitting tear dysfunctions appears... (Review)
Review
Symptoms of dryness discomfort in soft contact lens wearers frequently lead to discontinuation from wear. The negative influence of pre-fitting tear dysfunctions appears likely to be exacerbated by the challenges to tear homeostasis caused by contact lenses. The corneal mechanisms for symptoms in contact lens wearers are different to those for dry eye disease because the cornea is insulated by the lens from ambient conditions as well as from lid wiper friction during blinking. Symptoms of dryness discomfort might be the consequence of increased lid wiper friction during blinking when the lens front surface becomes soiled and dry and exhibits very rapid tear break up. It is possible that some cases of contact lens intolerance and discontinuation could be a function of lid wiper neuropathy. In relation to the possibility of corneal neuropathy, a stagnant post-lens tear pool with the possibility of increased concentrations of metabolic by-products, cellular debris, and bacterial exotoxins, might have the potential to disturb the corneal epithelial and sub-basal nerves. Contributions by contact lens-induced inflammation to any neuropathic changes may partly depend on the degree to which inflammatory mediators are concentrated in a stagnant post-lens tear pool. It does not appear to be known if corneal neuropathic changes could develop under these conditions. The chances of neuropathic involvement may be greater if discomfort develops after a significant period of successful wear and there is a history of comorbid pain conditions. Esthesiometry and in vivo confocal microscopy in discontinued contact lens wearers may support a diagnosis of contact lens-related corneal neuralgia.
PubMed: 33820563
DOI: 10.1186/s40662-021-00236-4 -
Acta Ophthalmologica Feb 2011To identify a rapid and effective tear collection method providing sufficient tear volume and total protein content (TPC) for analysis of individual proteins in cats. (Comparative Study)
Comparative Study
PURPOSE
To identify a rapid and effective tear collection method providing sufficient tear volume and total protein content (TPC) for analysis of individual proteins in cats.
METHODS
Domestic adult short-haired cats (12-37 months; 2.7-6.6 kg) were used in the study. Basal tears without stimulation and eye-flush tears after instillation of saline (10 μl) were collected using microcapillary tubes from animal eyes either unwounded control or wounded with 9-mm central epithelial debridement giving four groups with n = 3. Tear comparisons were based on total time and rate for tear collection, TPC using micro bicinchoninic acid (BCA), tear immunoglobulin A (IgA), total matrix-metalloproteinase (MMP)-9 concentration using sandwich enzyme-linked immunosorbent assay (ELISA) and MMP-9 activity.
RESULTS
Eye-flush tears were collected significantly faster than basal tears in wounded eyes with higher rates for tear collection in unwounded control and wounded eyes. TPC was significantly lower in eye-flush tears compared to basal tears. The relative proportion of tear IgA normalized to TPC (% IgA of TPC) was not significantly different between basal and eye-flush tears. In unwounded control eyes, MMP-9 was slightly higher in eye-flush than in basal tears; activity of MMP-9 in both tear types was similar. In wounded eyes, eye-flush tears showed highest MMP-9 levels and activity on Day 1, which subsequently decreased to Day 7. MMP-9 activity in basal tears from wounded eyes did not display changes in expression.
CONCLUSIONS
Eye-flush tears can be collected rapidly providing sufficient tear volume and TPC. This study also indicates that eye-flush tears may be more suitable than basal tears for the analysis of MMPs following corneal wounding.
Topics: Animals; Cats; Enzyme-Linked Immunosorbent Assay; Eye Proteins; Female; Immunoglobulin A; Male; Matrix Metalloproteinase 9; Specimen Handling; Tears
PubMed: 21272282
DOI: 10.1111/j.1755-3768.2010.02082.x -
Investigative Ophthalmology & Visual... Jan 2023To reveal the role of cold-sensing transient receptor potential melastatin 8 (TRPM8) channels in corneal epithelial wound healing.
PURPOSE
To reveal the role of cold-sensing transient receptor potential melastatin 8 (TRPM8) channels in corneal epithelial wound healing.
METHODS
Cold sensitivity, tear production, corneal thickness, and corneal opacity assessments were used to evaluate the effect of Trpm8 knockout on the ocular surface. A corneal epithelial wounding model was generated by scraping the corneal epithelium once or multiple times using C57BL/6J (wild-type [WT]) and Trpm8-/- mice. The processes of corneal epithelial repair and corneal epitheliopathy were observed and recorded. Corneas were collected for sequencing, immunofluorescence staining, hematoxylin and eosin staining, and quantitative PCR.
RESULTS
The perception of coldness, basal tear secretion, and corneal thickness were decreased in young Trpm8-/- mice compared with those in WT mice, except for the corneal sensitivity. Corneal opacity and increased corneal thickness were observed in aged Trpm8-/- mice. TRPM8 deficiency promoted corneal epithelial wound closure, consistent with the observed increase in Ki67-positive epithelial cells, and the pharmacological activation of TRPM8 in WT mice delayed corneal re-epithelization. After subjecting mice to multiple injuries, squamous metaplasia emerged in Trpm8-/- corneas, as verified by cytokeratin-1 and small proline-rich protein 1B-positive staining. The IFN-β and IFN-γ signaling pathways were significantly activated in Trpm8-/- mice, which was confirmed based on the up-regulated expression of the key mediators, signal transducer and activator of transcription-1 and phosphor-signal transducer and activator of transcription-1, as well as the induction of IFN-stimulated genes, compared with levels in WT mice.
CONCLUSIONS
In corneal wound healing, the loss of TRPM8 function could promote epithelial repair, but predispose the cornea to epithelial lesions.
Topics: Mice; Animals; Mice, Inbred C57BL; Corneal Injuries; Cornea; Epithelium, Corneal; Wound Healing; Corneal Opacity; TRPM Cation Channels
PubMed: 36692471
DOI: 10.1167/iovs.64.1.19 -
Diagnostics (Basel, Switzerland) Jul 2021To report the ocular surface pathology of patients suffering from acute/subacute mercury vapor intoxication.
PURPOSE
To report the ocular surface pathology of patients suffering from acute/subacute mercury vapor intoxication.
DESIGN
Cross-sectional study.
PARTICIPANTS
Male workers intoxicated with inorganic mercury referred for ophthalmic involvement and healthy control subjects.
METHODS
The following tests were performed: dry eye (DE)-related symptoms indicated by the ocular surface disease (OSDI) index questionnaire; tear osmolarity; analysis of 23 tear cytokine concentrations and principal component and hierarchical agglomerative cluster analyses; tear break-up time (T-BUT); corneal fluorescein and conjunctival lissamine green staining; tear production by Schirmer and tear lysozyme tests; mechanical and thermal corneal sensitivity (non-contact esthesiometry); and corneal nerve analysis and dendritic cell density by in vivo confocal microscopy (IVCM).
RESULTS
Twenty-two out of 29 evaluated patients entered the study. Most had DE-related symptoms (OSDI values > 12), that were severe in 63.6% of them. Tear osmolarity was elevated (>308 mOsms/L) in 83.4% of patients (mean 336.23 (28.71) mOsm/L). Corneal and conjunctival staining were unremarkable. T-BUT was low (<7 s) in 22.7% of patients. Schirmer test and tear lysozyme concentration were low in 13.6% and 27.3% of cases, respectively. Corneal esthesiometry showed patient mechanical (mean 147.81 (53.36) mL/min) and thermal thresholds to heat (+2.35 (+1.10) °C) and cold (-2.57 (-1.24) °C) to be significantly higher than controls. Corneal IVCM revealed lower values for nerve density (6.4 (2.94) n/mm), nerve branching density (2 (2.50) n/mm), and dendritic cell density (9.1 (8.84) n/mm) in patients. Tear levels of IL-12p70, IL-6, RANTES, and VEGF were increased, whereas EGF and IP-10/CXCL10 were decreased compared to controls. Based on cytokine levels, two clusters of patients were identified. Compared to Cluster 1, Cluster 2 patients had significantly increased tear levels of 18 cytokines, decreased tear lysozyme, lower nerve branching density, fewer dendritic cells, and higher urine mercury levels.
CONCLUSIONS
Patients suffering from systemic mercury intoxication showed symptoms and signs of ocular surface pathology, mainly by targeting the trigeminal nerve, as shown by alterations in corneal sensitivity and sub-basal nerve morphology.
PubMed: 34441261
DOI: 10.3390/diagnostics11081326 -
Acta Ophthalmologica Dec 2021To assess and compare corneal sub-basal nerve plexus morphology with circulating lymphocyte subsets, immunologic status and disease activity in Sjögren syndrome (SjS)...
PURPOSE
To assess and compare corneal sub-basal nerve plexus morphology with circulating lymphocyte subsets, immunologic status and disease activity in Sjögren syndrome (SjS) patients.
METHODS
Fifty-five SjS patients, 63 Sicca patients (not fulfilling SjS criteria), 18 rheumatoid arthritis (RA) patients and 20 healthy controls (HC) were included. Systemic disease activity in SjS was assessed with the ESSDAI score. Lymphocyte subpopulations were studied with flow cytometry. Corneal confocal microscopy and ImageJ software were used to characterize corneal sub-basal nerve plexus in terms of nerve density (CNFD), length (CNFL) and tortuosity (CNFT). Conventional dry eye tests were also performed.
RESULTS
CNFL and CNFD were lower in SjS, Sicca and RA groups, compared to HC (p < 0.001 for both SjS and Sicca); CNFL p = 0.005, CNFD p = 0.018 in RA). CNFT was higher in SjS, followed by Sicca, RA and HC. A negative correlation was found between ESSDAI score and CNFL (r=-0.735, p = 0.012). CNFL correlated negatively with IL21 CD8 T cells (r=-0.279, p = 0.039) and a positively with total memory (r = 0.299, p = 0.027), unswitched memory (r = 0.281, p = 0.038) and CD24 CD27 (r = 0.278, p = 0.040) B cells. CNFD showed a tendency to significance in its negative correlation with ESSDAI (r=-0.592, p = 0.071) and in its positive correlation with switched memory B cells (r = 0.644, p = 0.068).
CONCLUSIONS
This is the first study aiming to correlate ocular findings with lymphocyte subsets in SjS. The associations founded between CNFL and CNFD and disease activity, IL21 follicular T cells and some B-cell subsets suggest that corneal nerve damage may parallel systemic disease activity and inflammatory cells' dynamics.
Topics: Cell Count; Cornea; Female; Flow Cytometry; Humans; Immunity, Cellular; Lymphocyte Subsets; Male; Microscopy, Confocal; Middle Aged; Nerve Fibers; Sjogren's Syndrome; Tears
PubMed: 33683020
DOI: 10.1111/aos.14811 -
Molecular Vision 2017To determine the optimal tear collection method for analysis of ocular surface mucins MUC5AC and MUC16. (Comparative Study)
Comparative Study
PURPOSE
To determine the optimal tear collection method for analysis of ocular surface mucins MUC5AC and MUC16.
METHODS
Fifteen subjects without ocular surface disease were recruited. Subjects presented for tear collection on three separate days for three different tear collection methods with the order of method randomized. Methods used to collect tears from right and left eyes included Schirmer's strip, basal tear collection, and flush tear collection. All samples from the right eyes were individually analyzed for MUC5AC whereas the left eye samples were individually analyzed for MUC16. For each individual sample, 10 μg of protein were loaded per lane into a 1% (w/v) agarose gel and run in electrophoresis buffer for 2 h. After overnight capillary transfer, membranes were incubated with either MUC5AC antibody CLH2 or MUC16 antibody OC125 for western blot analysis. Blots were developed with enhanced chemiluminescence (ECL) and signals captured with the Odyssey Fc (LI-COR). The relative amounts of MUC5AC and MUC16 were quantified with densitometry using software and compared for statistically significant differences between tear collection methods using the Kruskal-Wallis test in SPSS 22 and GraphPad Prism 7.02. Dunn's multiple comparisons test was used for pairwise post-hoc comparisons.
RESULTS
Samples containing less than 10 μg of total protein were not used for analysis which left eight samples (out of 45) unusable. The calculated MUC5AC median signal intensities from Schirmer's strip, basal tears, and flush tears were 2.86 (n = 15, the interquartile range [IQR] = 2.54-3.21), 1.65 (n = 14, IQR = 1.34-3.1), and 1.67 (n = 9, IQR = 1.42-1.72), respectively (H = 9.5, p = 0.009). Post-hoc pairwise comparisons showed a statistically significant difference between Schirmer's strip and flush tears (p = 0.01). The calculated MUC16 median signal intensities from Schirmer's strip, basal tears, and flush tears were 1.88 (n = 14, IQR = 1.43-2.61), 5.24 (n = 15, IQR = 4.16-6.21), and 2.45 (n = 7, IQR = 1.85-2.48), respectively (H = 18.1, p = 0.001). Post-hoc pairwise comparison showed statistically significant differences between basal tears and Schirmer's strip (p = 0.0003) and between basal tears and flush tears (p = 0.006).
CONCLUSIONS
MUC5AC and MUC16 are present in human tear fluid and can be captured using various tear collection methods. Although basal tear collection yielded the highest relative concentration of MUC16, Schirmer's strip tear collection yielded the highest MUC5AC concentration. Therefore, the tear collection method chosen depends on the mucin of interest.
Topics: Adult; Blotting, Western; CA-125 Antigen; Densitometry; Electrophoresis, Agar Gel; Eye Proteins; Female; Healthy Volunteers; Humans; Male; Membrane Proteins; Mucin 5AC; Specimen Handling; Tears; Young Adult
PubMed: 28761326
DOI: No ID Found -
Investigative Ophthalmology & Visual... Jan 2022Patients receiving chemotherapy may experience ocular discomfort and dry eye-like symptoms; the latter may be neuropathic in nature. This study assessed corneal and...
PURPOSE
Patients receiving chemotherapy may experience ocular discomfort and dry eye-like symptoms; the latter may be neuropathic in nature. This study assessed corneal and somatic hypersensitivity in male rats treated with paclitaxel and whether it was relieved by nicotinamide riboside (NR).
METHODS
Corneal sensitivity to tactile and chemical stimulation, basal tear production, and sensitivity of the hindpaw to tactile and cool stimuli were assessed before and after paclitaxel in the absence and presence of sustained treatment with 500 mg/kg per os NR. Corneal nerve density and hindpaw intraepidermal nerve fiber (IENF) density were also examined.
RESULTS
Paclitaxel-treated rats developed corneal hypersensitivity to tactile stimuli, enhanced sensitivity to capsaicin but not hyperosmolar saline, and increased basal tear production. Corneal nerve density visualized with anti-β-tubulin or calcitonin gene-related peptide (CGRP) was unaffected. Paclitaxel induced tactile and cool hypersensitivity of the hindpaw and a loss of nonpeptidergic hindpaw IENFs visualized with anti-protein gene product (PGP) 9.5 and CGRP. NR reversed tactile hypersensitivity of the cornea without suppressing tear production or chemosensitivity; it did not alter corneal afferent density. NR also reversed tactile and cool hypersensitivity of the hindpaw without reversing the loss of hindpaw IENFs.
CONCLUSIONS
These findings suggest that paclitaxel may be a good translational model for chemotherapy-induced ocular discomfort and that NR may be useful for its relief. The ability of NR to relieve somatic tactile hypersensitivity independent of changes in sensory nerve innervation suggests that reversal of terminal arbor degeneration is not critical to the actions of NR.
Topics: Animals; Corneal Diseases; Disease Models, Animal; Hypersensitivity; Male; Niacinamide; Paclitaxel; Rats; Rats, Sprague-Dawley; Tears; Vitamin B Complex
PubMed: 35084430
DOI: 10.1167/iovs.63.1.38 -
Experimental Eye Research May 2009The lacrimal functional unit (LFU) is defined by the 2007 International Dry Eye WorkShop as 'an integrated system comprising the lacrimal glands, ocular surface (cornea,... (Review)
Review
The lacrimal functional unit (LFU) is defined by the 2007 International Dry Eye WorkShop as 'an integrated system comprising the lacrimal glands, ocular surface (cornea, conjunctiva and meibomian glands) and lids, and the sensory and motor nerves that connect them'. The LFU maintains a healthy ocular surface primarily through a properly functioning tear film that provides protection, lubrication, and an environment for corneal epithelial cell renewal. LFU cells express thousands of proteins. Over 200 new LFU proteins have been discovered in the last decade. Lacritin is a new LFU-specific growth factor in human tears that flows through ducts to target corneal epithelial cells on the ocular surface. When applied topically in rabbits, lacritin appears to increase the volume of basal tear secretion. Lacritin is one of only a handful of tear proteins preliminarily reported to be downregulated in blepharitis and in two dry eye syndromes. Computational analysis predicts an ordered C-terminal domain that binds the corneal epithelial cell surface proteoglycan syndecan-1 (SDC1) and is required for lacritin's low nanomolar mitogenic activity. The lacritin-binding site on the N-terminus of SDC1 is exposed by heparanase. Heparanase is constitutively expressed by the corneal epithelium and appears to be a normal constituent of tears. Binding triggers rapid signaling to downstream NFAT and mTOR. A wealth of other new proteins, originally designated as hypothetical when first identified by genomic sequencing, are expressed by the human LFU including: ALS2CL, ARHGEF19, KIAA1109, PLXNA1, POLG, WIPI1 and ZMIZ2. Their demonstrated or implied roles in human genetic disease or basic cellular functions are fuel for new investigation. Addressing topical areas in ocular surface physiology with new LFU proteins may reveal interesting new biological mechanisms and help get to the heart of ocular surface dysfunction.
Topics: Animals; Autoimmune Diseases; Cornea; Dry Eye Syndromes; Eye Proteins; Gene Expression Regulation; Genetic Diseases, Inborn; Genetic Predisposition to Disease; Glycoproteins; Humans; Lacrimal Apparatus; Signal Transduction; Structure-Activity Relationship
PubMed: 18840430
DOI: 10.1016/j.exer.2008.09.002 -
Investigative Ophthalmology & Visual... Jul 2018The Meibomian gland (MG) produces the lipid layer of the tear film, and changes to the MG that lead to a decrease or alteration in lipid quality/content may lead to MG...
PURPOSE
The Meibomian gland (MG) produces the lipid layer of the tear film, and changes to the MG that lead to a decrease or alteration in lipid quality/content may lead to MG dysfunction, a major cause of evaporative dry eye disease with prevalence ranging from 39% to 50%. Little is known about the developmental cues that regulate MG morphogenesis and homeostasis. Our study investigates the role of hyaluronan (HA), a major extracellular matrix component, in eyelid formation and MG development and function.
METHODS
Hyaluronan synthase (Has) knockout mice were used to determine the role of HA in the eyelid and MG. Eyelids were obtained during different developmental stages and MG morphology was analyzed. Tet-off H2B-GFP/K5tTA mice and 5-ethynyl-2'-deoxyurdine (EdU) incorporation were used to determine the role of HA in maintaining slow-cycling and proliferating cells within the MG, respectively. Data were confirmed using an in vitro proliferation assay, differentiation assay and spheroid cultures.
RESULTS
Has knockout mice present precocious MG development, and adult mice present MG hyperplasia and dysmorphic MGs and eyelids, with hyperplastic growths arising from the palpebral conjunctiva. Our data show that a highly organized HA network encompasses the MG, and basal cells are embedded within this HA matrix, which supports the proliferating cells. Spheroid cultures showed that HA promotes acini formation.
CONCLUSIONS
HA plays an important role in MG and eyelid development. Our findings suggest that Has knockout mice have abnormal HA synthesis, which in turn leads to precocious and exacerbated MG morphogenesis culminating in dysmorphic eyelids and MGs.
Topics: Adjuvants, Immunologic; Animals; Cell Differentiation; Cells, Cultured; Eyelids; Hyaluronic Acid; Immunohistochemistry; Meibomian Glands; Mice; Mice, Knockout; Models, Animal; Morphogenesis; Tears
PubMed: 30046813
DOI: 10.1167/iovs.18-24292