Cornea Publications

Brockhausen I, Elimova E, Woodward AM, Argüeso P. Glycosylation pathways of human corneal and conjunctival epithelial cell mucins. Carbohydr Res 2018;470:50-56.Abstract
Mucin glycoproteins on the ocular surface are rich in O-glycans and have important roles in the protection from physical, chemical and microbial impact. In this work, we have cultured human corneal and conjunctival epithelial cells to examine the glycosyltransferase activities that synthesize the O-glycans of mucins. The results indicate that ocular surface epithelial cells have active enzymes that synthesize O-glycans with sialylated core 1, Galβ1-3GalNAcα, and core 2, GlcNAcβ1-6(Galβ1-3)GalNAcα structures which corresponds to previous structural studies. Eye cells also have enzymes that synthesize complex N-glycans that are found on mucins. Results from treatment of eye cells with TNFα suggest that epithelial O-glycosylation changes in a dynamic fashion during inflammatory stimuli of the eye surface.
Kaye R, Botten N, Lippestad M, Li D, Hodges RR, Utheim TP, Serhan CN, Dartt DA. Resolvin D1, but not resolvin E1, transactivates the epidermal growth factor receptor to increase intracellular calcium and glycoconjugate secretion in rat and human conjunctival goblet cells. Exp Eye Res 2018;180:53-62.Abstract
PURPOSE: To identify interactions of the epidermal growth factor receptor (EGFR) with the pro-resolving mediator receptors for RvD1 and RvE1 to stimulate an increase in intracellular [Ca] ([Ca]) and mucin secretion from cultured human and rat conjunctival goblet cells. METHODS: Goblet cells from human and rat conjunctiva were grown in culture using RPMI media. Cultured goblet cells were pre-incubated with inhibitors, and then stimulated with RvD1, RvE1, EGF or the cholinergic agonist carbachol (Cch). Increase in [Ca] was measured using fura-2/AM. Goblet cell secretion was measured using an enzyme-linked lectin assay with UEA-1. Western blot analysis was performed with antibodies against AKT and ERK 1/2. RESULTS: In cultured human conjunctival goblet cells RvE1 -stimulated an increase in [Ca]. RvD1-, but not the RvE1-, stimulated increase in [Ca] and mucin secretion was blocked by the EGFR inhibitor AG1478 and siRNA for the EGFR. RvD1-, but not RvE1-stimulated an increase in [Ca] that was also inhibited by TAPI-1, an inhibitor of the matrix metalloprotease ADAM 17. Inhibition of the EGFR also blocked RvD1-stimulated increase in AKT activity and both RvD1-and RvE1-stimulated increase in ERK 1/2 activity. Pretreatment with either RvD1 or RvE1 did not block the EGFR-stimulated increase in [Ca]. CONCLUSIONS: We conclude that in cultured rat and human conjunctival goblet cells, RvD1 activates the EGFR, increases [Ca], activates AKT and ERK1/2 to stimulate mucin secretion. RvE1 does not transactivate the EGFR to increase [Ca] and stimulate mucin secretion, but does interact with the receptor to increase ERK 1/2 activity.
Adil MY, Xiao J, Olafsson J, Chen X, Lagali NS, Ræder S, Utheim ØA, Dartt DA, Utheim TP. Meibomian Gland Morphology is a Sensitive Early Indicator of Meibomian Gland Dysfunction. Am J Ophthalmol 2018;Abstract
PURPOSE: To investigate the relationship between meibomian gland (MG) morphology and clinical dry eye tests in patients with meibomian gland dysfunction (MGD). DESIGN: Cross-sectional study. SUBJECTS: Total 538 MGD patients, and 21 healthy controls. METHODS: MG loss on meibography images of upper (UL) and lower lids (LL) was graded on a scale of 0 (lowest degree of MG loss) to 3. MG length, thickness and inter-glandular space in the UL were measured. Clinical tests included meibum expression and quality, tear-film breakup time, ocular staining, osmolarity, Schirmer I, blink interval timing and Ocular Surface Disease Index (OSDI) questionnaire. RESULTS: Mean UL and LL meibogrades were significantly higher in MGD patients compared to controls (P < 0.001 for UL and LL). The sensitivity and specificity of the meibograde as a diagnostic parameter for MGD was 96.7% and 85%, respectively. Schirmer I was significantly increased in MGD patients with meibograde 1 compared to patients with meibograde 0, 2 and 3 in the UL (P < 0.05). MG thickness increased with higher meibograde (P < 0.001). MG morphology correlated significantly but weakly with several clinical parameters (P < 0.05). OSDI did not correlate with any MG morphological parameter. CONCLUSIONS: Grading of MG loss using meibograde effectively diagnoses MGD. Compensatory mechanisms such as increased aqueous tear production and dilatation of MGs make early detection of MGD difficult by standard clinical measures of dry eye, whereas morphologic analysis of MGs reveals an early stage of MGD, and therefore represent a complementary clinical parameter with diagnostic potential.
Inomata T, Nakamura M, Iwagami M, Shiang T, Yoshimura Y, Fujimoto K, Okumura Y, Eguchi A, Iwata N, Miura M, Hori S, Hiratsuka Y, Uchino M, Tsubota K, Dana R, Murakami A. Risk Factors for Severe Dry Eye Disease: Crowdsourced Research Using DryEyeRhythm. Ophthalmology 2018;Abstract
This large-scale crowdsourced study using the iPhone application DryEyeRhythm identified the risk factors for severe dry eye disease-type symptoms, which included female sex, collagen disease, hay fever, depression, current contact-lens use, extended screen time, and smoking.
Liu Y, Chen D, Chen X, Kam WR, Hatton MP, Sullivan DA. Hypoxia: A breath of fresh air for the meibomian gland. Ocul Surf 2018;Abstract
PURPOSE: Optimal meibomian gland (MG) function is critically important for the health and wellbeing of the ocular surface. We hypothesize that low oxygen (O) conditions promote the function of human MG epithelial cells (HMGECs) and that human MGs exist in a relatively hypoxic environment. The purpose of this study was to test our hypotheses. METHODS: We used human and mouse eyelid segments, and immortalized human MG epithelial cells (IHMGECs) in our studies. To evaluate oxygen (O) levels in the mouse MG and vicinity, we injected pimonidazole (pimo), a hypoxia marker, before sacrifice. Human eyelid samples were stained with the hypoxia marker glucose transporter 1 (Glut-1). To determine the effect of low O levels on IHMGECs, we cultured cells under proliferating and differentiating conditions in both normoxic (21% O) and hypoxic (3% O) conditions for 5-15 days. IHMGECs were evaluated for cell number, neutral lipid content, lysosome accumulation, expression of biomarker proteins and DNase II activity. RESULTS: Our results demonstrate that human and mouse MGs, but not the surrounding connective tissue, exist in a relatively hypoxic environment in vivo. In addition, our findings show that hypoxia does not influence IHMGEC numbers in basal or proliferating culture conditions, but does stimulate the expression of SREBP-1 in differentiating IHMGECs. Hypoxia also significantly increased DNase II activity, and apparently IHMGEC terminal differentiation. CONCLUSIONS: Our Results support our hypotheses, and indicate that relative hypoxia promotes MG function.
Tellefsen S, Morthen MK, Richards SM, Lieberman SM, Rahimi Darabad R, Kam WR, Sullivan DA. Sex Effects on Gene Expression in Lacrimal Glands of Mouse Models of Sjögren Syndrome. Invest Ophthalmol Vis Sci 2018;59(13):5599-5614.Abstract
Purpose: Sjögren syndrome is an autoimmune disease that occurs primarily in women, and is associated with lacrimal gland inflammation and aqueous-deficient dry eye. We hypothesize that sex-associated differences in lacrimal gland gene expression are very important in promoting lymphocyte accumulation in this tissue and contribute to the onset, progression, and/or severity of the inflammatory disease process. To test our hypothesis, we explored the nature and extent of sex-related differences in gene expression in autoimmune lacrimal glands. Methods: Lacrimal glands were collected from age-matched, adult, male and female MRL/MpJ-Tnfrsf6lpr (MRL/lpr) and nonobese diabetic/LtJ (NOD) mice. Glands were processed for the analysis of differentially expressed mRNAs by using CodeLink Bioarrays and Affymetrix GeneChips. Data were evaluated with bioinformatics and statistical software. Results: Our results show that sex significantly influences the expression of thousands of genes in lacrimal glands of MRL/lpr and NOD mice. The immune nature of this glandular response is very dependent on the Sjögren syndrome model. Lacrimal glands of female, as compared with male, MRL/lpr mice contain a significant increase in the expression of genes related to inflammatory responses, antigen processing, and chemokine pathways. In contrast, it is the lacrimal tissue of NOD males, and not females, that presents with a significantly greater expression of immune-related genes. Conclusions: These data support our hypothesis that sex-related differences in gene expression contribute to lacrimal gland disease in Sjögren syndrome. Our findings also suggest that factors in the lacrimal gland microenvironment are critically important in mediating these sex-associated immune effects.
Yin J, Jacobs DS. Long-term outcome of using Prosthetic Replacement of Ocular Surface Ecosystem (PROSE) as a drug delivery system for bevacizumab in the treatment of corneal neovascularization. Ocul Surf 2018;Abstract
PURPOSE: To report the long-term outcome of Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) for delivery of bevacizumab in the treatment of corneal neovascularization (KNV). METHODS: Retrospective, non-comparative, interventional case series of 13 sequential patients treated for KNV at the BostonSight between 2006 and 2017. In all cases, PROSE treatment was initiated for management of ocular surface disease and patients wore PROSE consistently on a daily wear basis prior to bevacizumab treatment. Patients applied a drop of 1% preservative free bevacizumab to the reservoir of PROSE device twice daily. Patients continued with daily wear of the device during treatment and afterwards. RESULTS: 13 patients (8 female and mean age of 45 years) are included with a mean follow-up of 5.1 years (range 6 months-11 years). Underlying ocular diagnoses included Stevens-Johnson syndrome (7), ocular chronic graft-versus-host disease (2), corneal transplant (2), contact lens-related corneal ulcer and limbal stem cell deficiency (1), and familial dysautonomia (1). Median duration of bevacizumab use was 6 months (range 3 months-10 years). Twelve cases (92%) had regression of KNV and 10 cases (77%) had improved best-corrected visual acuity (BCVA) with treatment. Median BCVA improved from -1.1 (LogMAR) at baseline, to -0.66 at end of bevacizumab treatment, and remained -0.63 at last follow-up (P = 0.047). KNV progressed in one eye after discontinuation of bevacizumab. There were no ophthalmic or systemic complications. CONCLUSIONS: Topical bevacizumab used in PROSE is effective in treating KNV and improving vision. Long-term follow-up reveals durable response and no complications.
Woodward AM, Lehoux S, Mantelli F, Di Zazzo A, Brockhausen I, Bonini S, Argüeso P. Inflammatory stress causes N-glycan processing deficiency in ocular autoimmune disease. Am J Pathol 2018;Abstract
High levels of proinflammatory cytokines have been associated with loss of tissue function in ocular autoimmune diseases but the basis for this relationship remains poorly understood. Here we investigated a new role for tumor necrosis factor (TNF)-α in promoting N-glycan processing deficiency at the surface of the eye through inhibition of N-acetylglucosaminyltransferase expression in the Golgi. Using mass spectrometry, complex-type biantennary oligosaccharides were identified as major N-glycan structures in differentiated human corneal epithelial cells. Remarkably, significant differences were detected between the efficacies of cytokines in regulating the expression of glycogenes responsible for the biosynthesis of N-glycans. TNFα but not interleukin-1β had a profound effect in suppressing the expression of enzymes involved in the Golgi branching pathway, including MGAT1 and 2, which are required for the formation of biantennary structures. This decrease in gene expression correlated with a reduction in enzymatic activity and impaired N-glycan branching. Moreover, patients with ocular mucous membrane pemphigoid were characterized by marginal N-acetylglucosaminyltransferase expression and decreased N-glycan branching in conjunctiva. Together, these data indicate that proinflammatory cytokines differentially influence the expression of N-glycan processing enzymes in the Golgi and set the stage for future studies to explore the pathophysiology of ocular autoimmune diseases.
Lopez MJ, Seyed-Razavi Y, Jamali A, Harris DL, Hamrah P. The Chemokine Receptor CXCR4 Mediates Recruitment of CD11c+ Conventional Dendritic Cells Into the Inflamed Murine Cornea. Invest Ophthalmol Vis Sci 2018;59(13):5671-5681.Abstract
Purpose: The cornea contains distinct populations of antigen-presenting cells (APCs), including conventional dendritic cells (cDCs). Little is known about the molecular mechanisms involved in cDCs homing and recruitment into the naïve and inflamed cornea. The purpose of this study was to investigate the presence of CXCR4 and its ligand CXCL12 in the murine cornea and its role in cDC migration during corneal inflammation. Methods: The expression of CXCR4 and CXCL12 in naïve and suture-inflamed murine corneas was assessed by whole-mount staining, flow cytometry, and quantitative PCR. The role of CXCR4 in recruitment into inflamed corneas was investigated using adoptive transfer of cDCs blocked with neutralizing antibody against CXCR4. Results: We show the chemokine receptor CXCR4 to be expressed on 51.7% and 64.8% of total corneal CD11c+ cDCs, equating to 98.6 ± 12.5 cells/mm2 in the peripheral and 64.7 ± 10.6 cells/mm2 in the central naïve cornea, respectively. Along with a 4.5-fold increase in CXCL12 expression during inflammation (P < 0.05), infiltrating cDCs also expressed CXCR4 in both the peripheral (222.6 ± 33.3 cells/mm2; P < 0.001) and central cornea (161.9 ± 23.8 cells/mm2; P = 0.001), representing a decrease to 31.0% and 37.3% in the cornea, respectively. Further, ex vivo blockade (390.1 ± 40.1 vs. 612.1 ± 78.3; P = 0.008) and local blockade (263.5 ± 27.1 vs. 807.5 ± 179.5, P < 0.001) with anti-CXCR4 neutralizing antibody resulted in a decrease in cDCs homing into the cornea compared with cells pretreated with isotype controls. Conclusions: Our results demonstrate that corneal CXCL12 plays a direct role in CXCR4+ cDC recruitment into the cornea. The CXCR4/CXCL12 axis is therefore a potential target to modulate corneal inflammatory responses.
Jurkunas UV. Fuchs Endothelial Corneal Dystrophy Through the Prism of Oxidative Stress. Cornea 2018;37 Suppl 1:S50-S54.Abstract
The corneal endothelium (CE) is vital for maintaining the water balance and clarity of the cornea. The CE is a cell layer that is particularly susceptible to aging because of its postmitotic arrest, high metabolic activity involving pumping of ions, and lifelong exposure to ultraviolet light. Despite gradual age-related cell loss, a sufficient number of CE cells are preserved during the lifespan of an individual. However, in conditions such as Fuchs endothelial corneal dystrophy (FECD), permanent loss of CE cells leads to corneal edema and loss of vision requiring corneal transplantation. FECD is a genetic and oxidative stress disorder manifested by abnormal cell-matrix interactions and expedited cellular aging culminating in cellular death. Because the endothelium has minimal replicative capacity in vivo and an inability to replace its genome, it is particularly prone to cumulative DNA damage acquired throughout life. In FECD, the underlying genetic defects make the CE genome even more vulnerable to this damage, to the point of causing mitochondrial dysfunction, mitochondrial membrane potential loss, and excessive mitophagy activation. Endogenous and exogenous intracellular stressors alter the synthetic footprint of CE cells, leading to endothelial-mesenchymal transition and secretion of aberrant extracellular matrix (in the form of guttae), resembling scar formation in other organs. In turn, the guttae or endothelial scars contribute to a vicious cycle of FECD pathogenesis and, by further inducing endothelial-mesenchymal transition and oxidant-antioxidant imbalance, perpetuate the molecular changes of the degenerating endothelium.
Kobashi H, Rong SS, Ciolino JB. Transepithelial versus epithelium-off corneal crosslinking for corneal ectasia. J Cataract Refract Surg 2018;44(12):1507-1516.Abstract
This review compared the clinical results of transepithelial corneal crosslinking (CXL) to epithelium-off (epi-off) CXL in progressive corneal ectasia using a metaanalysis. The Cochrane databases and Medline were searched for randomized controlled trials (RCTs). Seven RCTs involving 505 eyes that met the eligibility criteria were identified. The epi-off CXL group showed significantly better outcomes in postoperative changes in maximum keratometry (K) during 1-year observation periods. Transepithelial CXL resulted in significantly greater post-treatment central corneal thickness and best spectacle-corrected visual acuity (BSCVA). The presence of a postoperative demarcation line was significantly more frequent after epi-off CXL than that after transepithelial CXL. No statistically significant difference was found between other parameters. Although patients in the transepithelial CXL group demonstrated a greater improvement in BSCVA compared with patients in the epi-off CXL group at the 1 year follow-up, transepithelial CXL had less impact on halting progressive corneal ectasia in terms of maximum K than epi-off CXL.
Tatematsu Y, Khan Q, Blanco T, Bair JA, Hodges RR, Masli S, Dartt DA. Thrombospondin-1 Is Necessary for the Development and Repair of Corneal Nerves. Int J Mol Sci 2018;19(10)Abstract
Thrombospondin-1-deficient (TSP-1) mice are used as an animal model of Sjögren's Syndrome because they exhibit many of the symptoms associated with the autoimmune type of dry eye found in primary Sjögren's Syndrome. This type of dry eye is linked to the inflammation of the lacrimal gland, conjunctiva, and cornea, and is thought to involve dysfunction of the complex neuronal reflex arc that mediates tear production in response to noxious stimuli on the ocular surface. This study characterizes the structural and functional changes to the corneal nerves that are the afferent arm of this arc in young and older TSP-1 and wild type (WT) mice. The structure and subtype of nerves were characterized by immunohistochemistry, in vivo confocal microscopy, and confocal microscopy. Cytokine expression analysis was determined by Q-PCR and the number of monocytes was measured by immunohistochemistry. We found that only the pro-inflammatory cytokine MIP-2 increased in young corneas of TSP-1 compared to WT mice, but tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2 (MIP-2) all increased in older TSP-1 mouse corneas. In contrast, CD11b+ pro-inflammatory monocytes did not increase even in older mouse corneas. Calcitonin gene-related peptide (CGRP)-, but not Substance P (SubP)-containing corneal nerves decreased in older, but not younger TSP-1 compared to WT mouse corneas. We conclude that CGRP-containing corneal sensory nerves exhibit distinct structural deficiencies as disease progresses in TSP-1 mice, suggesting that: (1) TSP-1 is needed for the development or repair of these nerves and (2) impaired afferent corneal nerve structure and hence function may contribute to ocular surface dysfunction that develops as TSP-1 mice age.
Gregory-Ksander M, Perez VL, Marshak-Rothstein A, Ksander BR. Soluble Fas ligand blocks destructive corneal inflammation in mouse models of corneal epithelial debridement and LPS induced keratitis. Exp Eye Res 2018;Abstract
Neutrophil-mediated inflammation plays a critical role in corneal damage following injury or infection. Previous studies demonstrated that membrane-bound FasL (mFasL) induces neutrophil chemokine production. However, the extracellular domain of mFasL is normally cleaved by matrix metalloproteinases to release a soluble form of FasL (sFasL) and sFasL antagonizes mFasL-mediated chemokine production. Therefore, we hypothesized that sFasL could be used to prevent neutrophil-mediated corneal inflammation associated with injury and bacterial keratitis. To test this hypothesis, GFP-only, sFasL-GFP, or mFasL-GFP were expressed in the corneal stroma of C57BL/6 mice, using intra-stromal injections of plasmid DNA or adenoviral vectors (AV) and the role of mFasL and sFasL in corneal inflammation was examined in models of corneal injury and LPS-induced keratitis. Our work addresses an important area of disagreement in the field of FasL, with regard to the mechanism by which sFasL regulates ocular inflammation. Herein, we demonstrate that an intrastromal injection of GFP-only, sFasL-GFP, or mFasL-GFP plasmid DNA resulted in GFP expression throughout the corneal stroma for up to two weeks with little to no evidence of inflammation in the GFP-only and sFasL-GFP groups and mild corneal inflammation in the mFasL-GFP group. Similarly, following epithelial debridement, corneas expressing GFP-only or sFasL-GFP showed no significant signs of corneal inflammation, with clear corneas at 15 days post debridement. By contrast, epithelial debridement of corneas expressing mFasL-GFP triggered persistent corneal inflammation and the development of central corneal opacities that was blocked by sFasL. Similar to the mFasL-GFP plasmid DNA, intrastromal injection of mFasL-GFP AV triggered mild corneal inflammation, but it was transient and resolved by day 10 with corneas remaining clear out to 30 days post injection. Nevertheless, intrastromal expression of mFasL-GFP AV exacerbated LPS-induced keratitis, corneal opacity, and neovascularization, while sFasL-GFP AV expression prevented LPS-induced keratitis, resulting in a clear cornea. Histological analysis of corneas with LPS-induced keratitis revealed a robust infiltration of macrophages and neutrophils and sFasL expression specifically blocked the neutrophil influx. Overall, our data demonstrate that stromal expression of mFasL is inflammatory, while sFasL is non-inflammatory, and opposes the effects of mFasL in mouse models of epithelial debridement and LPS-induced keratitis. These data demonstrate that a delicate balance between sFasL and mFasL regulates ocular inflammation. This study further identifies sFasL as a potent inhibitor of neutrophil-mediated corneal damage, and supports the potential use of sFasL in the treatment of neutrophil-mediated keratitis. These results strongly support the hypothesis that, in the immune privileged environment of the eye, the isoform of FasL regulates immune privilege and determines the extent of inflammation: mFasL promotes inflammation and sFasL blocks inflammation.
Saban DR, Hodges RR, Mathew R, Reyes NJ, Yu C, Kaye R, Swift W, Botten N, Serhan CN, Dartt DA. Resolvin D1 treatment on goblet cell mucin and immune responses in the chronic allergic eye disease (AED) model. Mucosal Immunol 2018;Abstract
Severe, chronic eye allergy is an understudied, vision-threatening condition. Treatments remain limited. We used a mouse model of severe allergic eye disease (AED) to determine whether topical application of the pro-resolution mediator Resolvin D1 (RvD1) terminates the response. AED was induced by injection of ovalbumin (OVA) followed by topical challenge of OVA daily. RvD1 was applied topically prior to OVA. Clinical symptoms were scored. Eye washes were assayed for MUC5AC. After 7 days, eyes were removed and the number of goblet cells, T helper cell responses and presence of immune cells in draining lymph nodes and conjunctiva determined. Topical RvD1 treatment significantly reduced symptoms of AED. RvD1 did not alter the systemic type 2 immune response in the lymph nodes. AED increased the total amount of goblet cell mucin secretion, but not the number of goblet cells. RvD1 prevented this increase, but did not alter goblet cell number. Absolute numbers of CD4 + T cells, total CD11b + myeloid cells, eosinophils, neutrophils, and monocytes, but not macrophages increased in AED versus RvD1-treated mice. We conclude that topical application of RvD1 reduced the ocular allergic response by local actions in conjunctival immune response and a decrease in goblet cell mucin secretion.
Webster A, Chintala SK, Kim J, Ngan M, Itakura T, Panjwani N, Argüeso P, Barr JT, Jeong S, Elizabeth Fini M. Dynasore protects the ocular surface against damaging stress. PLoS One 2018;13(10):e0204288.Abstract
Water soluble "vital" dyes are commonly used clinically to evaluate health of the ocular surface; however, staining mechanisms remain poorly understood. Recent evidence suggests that sublethal damage stimulates vital dye uptake by individual living cells. Since cell damage can also stimulate reparative plasma membrane remodeling, we hypothesized that dye uptake occurs via endocytic vesicles. In support of this idea, we show here that application of oxidative stress to relatively undifferentiated monolayer cultures of human corneal epithelial cells stimulates both dye uptake and endocytosis, and that dye uptake is blocked by co-treatment with three different endocytosis inhibitors. Stress application to stratified and differentiated corneal epithelial cell cultures, which are a better model of the ocular surface, also stimulated dye uptake; however, endocytosis was not stimulated, and two of the endocytosis inhibitors did not block dye uptake. The exception was Dynasore and its more potent analogue Dyngo-4a, both small molecules developed to target dynamin family GTPases, but also having off-target effects on the plasma membrane. Significantly, while Dynasore blocked stress-stimulated dye uptake at the ocular surface of ex vivo mouse eyes when treatment was performed at the same time as eyes were stressed, it had no effect when used after stress was applied and the ocular surface was already damaged. Thus, Dynasore could not be working by inhibiting endocytosis. Employing cytotoxicity and western blotting assays, we went on to demonstrate an alternative mechanism. We show that Dynasore is remarkably protective of cells and their surface glycocalyx, preventing damage due to stress, and thus precluding dye entry. These unexpected and novel findings provide greater insight into the mechanisms of vital dye uptake and point the direction for future study. Significantly, they also suggest that Dynasore and its analogues might be used therapeutically to protect the ocular surface and to treat ocular surface disease.