Cornea

McKay TB, Karamichos D, Hutcheon AEK, Guo X, Zieske JD. Corneal Epithelial-Stromal Fibroblast Constructs to Study Cell-Cell Communication in Vitro. Bioengineering (Basel) 2019;6(4)Abstract
Cell-cell communication plays a fundamental role in mediating corneal wound healing following injury or infection. Depending on the severity of the wound, regeneration of the cornea and the propensity for scar development are influenced by the acute resolution of the pro-fibrotic response mediated by closure of the wound via cellular and tissue contraction. Damage of the corneal epithelium, basement membrane, and anterior stroma following a superficial keratectomy is known to lead to significant provisional matrix deposition, including secretion of fibronectin and thrombospondin-1, as well as development of a corneal scar. In addition, corneal wounding has previously been shown to promote release of extracellular vesicles from the corneal epithelium, which, in addition to soluble factors, may play a role in promoting tissue regeneration. In this study, we report the development and characterization of a co-culture system of human corneal epithelial cells and corneal stromal fibroblasts cultured for 4 weeks to allow extracellular matrix deposition and tissue maturation. The secretion of provisional matrix components, as well as small and large extracellular vesicles, was apparent within the constructs, suggesting cell-cell communication between epithelial and stromal cell populations. Laminin-1β was highly expressed by the corneal epithelial layer with the presence of notable patches of basement membrane identified by transmission electron microscopy. Interestingly, we identified expression of collagen type III, fibronectin, and thrombospondin-1 along the epithelial-stromal interface similar to observations seen in vivo following a keratectomy, as well as expression of the myofibroblast marker, α-smooth muscle actin, within the stroma. Our results suggest that this corneal epithelial-stromal model may be useful in the study of the biochemical phenomena that occur during corneal wound healing.
Pan P, Weisenberger DJ, Zheng S, Wolf M, Hwang DG, Rose-Nussbaumer JR, Jurkunas UV, Chan MF. Aberrant DNA methylation of miRNAs in Fuchs endothelial corneal dystrophy. Sci Rep 2019;9(1):16385.Abstract
Homeostatic maintenance of corneal endothelial cells is essential for maintenance of corneal deturgescence and transparency. In Fuchs endothelial corneal dystrophy (FECD), an accelerated loss and dysfunction of endothelial cells leads to progressively severe visual impairment. An abnormal accumulation of extracellular matrix (ECM) is a distinctive hallmark of the disease, however the molecular pathogenic mechanisms underlying this phenomenon are not fully understood. Here, we investigate genome-wide and sequence-specific DNA methylation changes of miRNA genes in corneal endothelial samples from FECD patients. We discover that miRNA gene promoters are frequent targets of aberrant DNA methylation in FECD. More specifically, miR-199B is extensively hypermethylated and its mature transcript miR-199b-5p was previously found to be almost completely silenced in FECD. Furthermore, we find that miR-199b-5p directly and negatively regulates Snai1 and ZEB1, two zinc finger transcription factors that lead to increased ECM deposition in FECD. Taken together, these findings suggest a novel epigenetic regulatory mechanism of matrix protein production by corneal endothelial cells in which miR-199B hypermethylation leads to miR-199b-5p downregulation and thereby the increased expression of its target genes, including Snai1 and ZEB1. Our results support miR-199b-5p as a potential therapeutic target to prevent or slow down the progression of FECD disease.
Xiao J, Adil MY, Olafsson J, Chen X, Utheim ØA, Ræder S, Lagali NS, Dartt DA, Utheim TP. Diagnostic Test Efficacy of Meibomian Gland Morphology and Function. Sci Rep 2019;9(1):17345.Abstract
Meibomian gland dysfunction (MGD) is the leading cause of dry eye and proposed treatments are based on disease severity. Our purpose was to establish reliable morphologic measurements of meibomian glands for evaluating MGD severity. This retrospective, cross-sectional study included 100 MGD patients and 20 controls. The patients were classified into dry eye severity level (DESL) 1-4 based on symptoms and clinical parameters including tear-film breakup time, ocular staining and Schirmer I. The gland loss, length, thickness, density and distortion were analyzed. We compared the morphology between patients and controls; examined their correlations to meibum expressibility, quality, and DESL. Relative to controls, the gland thickness, density and distortion were elevated in patients (p < 0.001 for all tests). The area under the receiver operating characteristic curve was 0.98 (95% confidence interval [CI], 0.96-1.0) for gland loss, and 0.96 (CI 0.91-1.0) for gland distortion, with a cutoff value of six distorted glands yielding a sensitivity of 93% and specificity of 97% for MGD diagnosis. The gland distortion was negatively correlated to the meibum expressibility (r = -0.53; p < 0.001) and DESL (r = -0.22, p = 0.018). In conclusion, evaluation of meibomian gland loss and distortion are valuable complementary clinical parameters to assess MGD status.
Moulton EA, Borsook D. C-Fiber Assays in the Cornea vs. Skin. Brain Sci 2019;9(11)Abstract
C-fibers are unmyelinated nerve fibers that transmit high threshold mechanical, thermal, and chemical signals that are associated with pain sensations. This review examines current literature on measuring altered peripheral nerve morphology and discusses the most relevant aspects of corneal microscopy, especially whether corneal imaging presents significant method advantages over skin biopsy. Given its relative merits, corneal confocal microscopy would seem to be a more practical and patient-centric approach than utilizing skin biopsies.
Szczotka-Flynn LB, Maguire MG, Ying G-S, Lin MC, Bunya VY, Dana R, Asbell PA, and Group DEAM (DREAM) SR. Authors' Response. Optom Vis Sci 2019;96(11):892.
Inomata T, Iwagami M, Nakamura 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. Characteristics and Risk Factors Associated With Diagnosed and Undiagnosed Symptomatic Dry Eye Using a Smartphone Application. JAMA Ophthalmol 2019;Abstract
Importance: The incidence of dry eye disease has increased; the potential for crowdsource data to help identify undiagnosed dry eye in symptomatic individuals remains unknown. Objective: To assess the characteristics and risk factors associated with diagnosed and undiagnosed symptomatic dry eye using the smartphone app DryEyeRhythm. Design, Setting, and Participants: A cross-sectional study using crowdsourced data was conducted including individuals in Japan who downloaded DryEyeRhythm and completed the entire questionnaire; duplicate users were excluded. DryEyeRhythm was released on November 2, 2016; the study was conducted from November 2, 2016, to January 12, 2018. Exposures: DryEyeRhythm data were collected on demographics, medical history, lifestyle, subjective symptoms, and disease-specific symptoms, using the Ocular Surface Disease Index (100-point scale; scores 0-12 indicate normal, healthy eyes; 13-22, mild dry eye; 23-32, moderate dry eye; 33-100, severe dry eye symptoms), and the Zung Self-Rating Depression Scale (total of 20 items, total score ranging from 20-80, with ≥40 highly suggestive of depression). Main Outcomes and Measures: Multivariate-adjusted logistic regression analysis was used to identify risk factors for symptomatic dry eye and to identify risk factors for undiagnosed symptomatic dry eye. Results: A total of 21 394 records were identified in our database; 4454 users, included 899 participants (27.3%) with diagnosed and 2395 participants (72.7%) with undiagnosed symptomatic dry eye, completed all questionnaires and their data were analyzed. A total of 2972 participants (66.7%) were women; mean (SD) age was 27.9 (12.6) years. The identified risk factors for symptomatic vs no symptomatic dry eye included younger age (odds ratio [OR], 0.99; 95% CI, 0.987-0.999, P = .02), female sex (OR, 1.99; 95% CI, 1.61-2.46; P < .001), pollinosis (termed hay fever on the questionnaire) (OR, 1.35; 95% CI, 1.18-1.55; P < .001), depression (OR, 1.78; 95% CI, 1.18-2.69; P = .006), mental illnesses other than depression or schizophrenia (OR, 1.87; 95% CI, 1.24-2.82; P = .003), current contact lens use (OR, 1.27; 95% CI, 1.09-1.48; P = .002), extended screen exposure (OR, 1.55; 95% CI, 1.25-1.91; P < .001), and smoking (OR, 1.65; 95% CI, 1.37-1.98; P < .001). The risk factors for undiagnosed vs diagnosed symptomatic dry eye included younger age (OR, 0.96; 95% CI, 0.95-0.97; P < .001), male sex (OR, 0.55; 95% CI, 0.42-0.72; P < .001), as well as absence of collagen disease (OR, 95% CI, 0.23; 0.09-0.60; P = .003), mental illnesses other than depression or schizophrenia (OR, 0.50; 95% CI, 0.36-0.69; P < .001), ophthalmic surgery other than cataract surgery and laser-assisted in situ keratomileusis (OR, 0.41; 95% CI, 0.27-0.64; P < .001), and current (OR, 0.64; 95% CI, 0.54-0.77; P < .001) or past (OR, 0.45; 95% CI, 0.34-0.58; P < .001) contact lens use. Conclusions and Relevance: This study's findings suggest that crowdsourced research identified individuals with diagnosed and undiagnosed symptomatic dry eye and the associated risk factors. These findings could play a role in earlier prevention or more effective interventions for dry eye disease.
Asbell PA, Aquavella JV, Hamrah P, Pepose JS, Rose L, Ucakhan O. ISOPT Hot Topic Panel Discussion on Cornea Anterior Segment Disease. J Ocul Pharmacol Ther 2019;35(8):447-456.Abstract
The cornea and its adnexa pose a unique situation of a tightly defined set of requirements for its function. This includes: transparency, perfect built to obtain appropriate refractive power, protective barrier from microbial invaders. Moreso, the cornea also endures extreme external physical conditions (temperature, high and low humidity, winds and alike). All these functions are maintained while preserving a constant state of homogenous wetting. Toward that end the cornea is equipped with an elaborated network of sensory neural network. While enabling the blinking reflex and maintaining the physiological steady state of wetting, this neural network also makes the cornea prone to the discomfort that with or without associated changes seen on medical examination. ISOPT Clinical 2018 discussion touched upon this hypercomplex situation, addressing the role of inflammation and its resulting discomfort in dry eye conditions. The discussion also engulfed the emerging neuropathic pain syndrome that is recently gaining more attention. Another related topic was the utilization of autologous serum tears and its ability to provide amelioration to desperate patients. Finally, the panel discussed the issue of treating corneal infection, including when and how to utilize steroids in the course of therapy. We assume the reader will find interest in this discussion that directly addresses issues seen day in and day out in our busy clinics.
Deng SX, Borderie V, Chan CC, Dana R, Figueiredo FC, Gomes JAP, Pellegrini G, Shimmura S, Kruse FE. Reply. Cornea 2019;38(12):e56-e57.
Sabeti S, Kheirkhah A, Yin J, Dana R. Management of Meibomian Gland Dysfunction: A Review. Surv Ophthalmol 2019;Abstract
Meibomian gland dysfunction (MGD) is the leading cause of evaporative dry eye disease and is one of the most common conditions encountered by eye care providers. MGD is characterized by obstruction of the meibomian gland terminal ducts and/or changes in their glandular secretion, resulting in changes in tear film stability, inflammation, and symptoms of irritation. There is no gold standard treatment for MGD, but rather a diversity of options. Conservative measures include warm compresses and lid hygiene, but there is growing interest and need for medical treatments and procedures. Potential medical treatments include antibiotics, non-steroidal and steroidal anti-inflammatory agents, essential fatty acid supplementation, hormone therapy, and control of Demodex infestation. Procedures include intraductal meibomian gland probing, the use of electronic heating devices, intense pulsed light therapy, and intranasal neurostimulation. We provide an update on MGD treatments based on recent studies.
Pal-Ghosh S, Tadvalkar G, Lieberman VR, Guo X, Zieske JD, Hutcheon A, Stepp MA. Transient Mitomycin C-treatment of human corneal epithelial cells and fibroblasts alters cell migration, cytokine secretion, and matrix accumulation. Sci Rep 2019;9(1):13905.Abstract
A single application of Mitomycin C (MMC) is used clinically in ophthalmology to reduce scarring and enhance wound resolution after surgery. Here we show in vitro that a 3-hour MMC treatment of primary and telomerase immortalized human corneal limbal epithelial (HCLE) cells impacts their migration and adhesion. Transient MMC treatment induces HCLE expression of senescence associated secretory factors, cytokine secretion, and deposition of laminin 332 for several days. Transient MMC treatment also reduces migration and deposition of transforming growth factor-β1 (TGFβ1)-stimulated collagen by corneal fibroblasts. Using conditioned media from control and MMC treated cells, we demonstrate that factors secreted by MMC-treated corneal epithelial cells attenuate collagen deposition by HCFs whereas those secreted by MMC-treated HCFs do not. These studies are the first to probe the roles played by corneal epithelial cells in reducing collagen deposition by corneal fibroblasts in response to MMC.
Coco G, Kheirkhah A, Foulsham W, Dana R, Ciolino JB. Keratoconus progression associated with hormone replacement therapy. Am J Ophthalmol Case Rep 2019;15:100519.Abstract
Purpose: To report a postmenopausal patient with keratoconus who experienced significant progression after using hormone replacement therapy. Observations: A 51-year-old woman with previously stable keratoconus presented with acute disease progression following hormone replacement therapy in the context of prophylactic hysterectomy and bilateral ovariosalpingectomy. Over a 14-month period after starting hormone therapy, the steepest K increased from 63.7D to 71.5D in the right eye and from 65.8D to 78.1D in the left eye. Conclusions: Hormone replacement therapy may amplify progression of keratoconus.
Fini EM, Jeong S, Gong H, Martinez-Carrasco R, Laver NMV, Hijikata M, Keicho N, Argüeso P. Membrane-associated mucins of the ocular surface: New genes, new protein functions and new biological roles in human and mouse. Prog Retin Eye Res 2019;:100777.Abstract
The mucosal glycocalyx of the ocular surface constitutes the point of interaction between the tear film and the apical epithelial cells. Membrane-associated mucins (MAMs) are the defining molecules of the glycocalyx in all mucosal epithelia. Long recognized for their biophysical properties of hydration, lubrication, anti-adhesion and repulsion, MAMs maintain the wet ocular surface, lubricate the blink, stabilize the tear film and create a physical barrier to the outside world. However, it is increasingly appreciated that MAMs also function as cell surface receptors that transduce information from the outside to the inside of the cell. A number of excellent review articles have provided perspective on the field as it has progressed since 1987, when molecular cloning of the first MAM was reported. The current article provides an update for the ocular surface, placing it into the broad context of findings made in other organ systems, and including new genes, new protein functions and new biological roles. We discuss the epithelial tissue-equivalent with mucosal differentiation, the key model system making these advances possible. In addition, we make the first systematic comparison of MAMs in human and mouse, establishing the basis for using knockout mice for investigations with the complexity of an in vivo system. Lastly, we discuss findings from human genetics/genomics, which are providing clues to new MAM roles previously unimagined. Taken together, this information allows us to generate hypotheses for the next stage of investigation to expand our knowledge of MAM function in intracellular signaling and roles unique to the ocular surface.
Pennington MR, Saha A, Painter DF, Gavazzi C, Ismail AM, Zhou X, Chodosh J, Rajaiya J. Disparate Entry of Adenoviruses Dictates Differential Innate Immune Responses on the Ocular Surface. Microorganisms 2019;7(9)Abstract
Human adenovirus infection of the ocular surface is associated with severe keratoconjunctivitis and the formation of subepithelial corneal infiltrates, which may persist and impair vision for months to years following infection. Long term pathology persists well beyond the resolution of viral replication, indicating that the prolonged immune response is not virus-mediated. However, it is not clear how these responses are sustained or even initiated following infection. This review discusses recent work from our laboratory and others which demonstrates different entry pathways specific to both adenovirus and cell type. These findings suggest that adenoviruses may stimulate specific pattern recognition receptors in an entry/trafficking-dependent manner, leading to distinct immune responses dependent on the virus/cell type combination. Additional work is needed to understand the specific connections between adenoviral entry and the stimulation of innate immune responses by the various cell types present on the ocular surface.
Severinsky B, Fadel D, Davelman J, Moulton E. Effect of Scleral Lenses on Corneal Topography in Keratoconus: A Case Series of Cross-Linked Versus Non-Cross-Linked Eyes. Cornea 2019;38(8):986-991.Abstract
PURPOSE: To evaluate the changes in anterior corneal topography induced by short-time wear of scleral contact lenses (SLs) in keratoconic subjects with and without a history of corneal cross-linking (CXL). METHODS: Nine keratoconic patients (14 eyes) were fitted with 18.5 mm SLs for optical rehabilitation. Subjects were divided into 2 groups: 7 eyes without a history of CXL (Non-CXL group) and 7 with a history of CXL (CXL group). Corneal topography was performed at baseline and after 2 and 5 hours of lens wear. The differences for simulated flat (Kflat), steep (Ksteep) and maximal (Kmax) corneal curvatures, central corneal astigmatism (CCA), and central cornea thickness were evaluated. RESULTS: No statistically significant difference was detected between Non-CXL and CXL groups in any of these measures. Statistically significant flattening was detected in Ksteep Repeated measures analysis of variance ([RM-ANOVA), F (2,24) = 11.32, P < 0.0001], CCA [RM-ANOVA, F (2,24) = 15.34, P < 0.0001], and Kmax [RM-ANOVA, F (2,24) = 19.10, P < 0.0001). From baseline to 5 hours of SL wear, Ksteep decreased on average from 53.1 to 52.4 D, Kmax decreased from 56.7 to 55.8 D, and CCA decreased from 7.2 to 6.3 D. Kmax showed a trend toward more flattening in the Non-CXL group. Central cornea thickness showed significant thickening over time from baseline (451 μm) to 5 hours (458 μm) of SL wear [RM-ANOVA, F (1,12) = 319.3, P < 0.0001]. CONCLUSIONS: Short-term scleral lens wear in keratoconic patients may cause flattening of the anterior cornea. A history of CXL treatment does not guarantee corneal shape stability after scleral lens wear. Practitioners should be aware of these changes because scleral lens wear may mask the signs of keratoconus progression.

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