Cornea

Ting DSJ, Foo VH, Yang LWY, Sia JT, Ang M, Lin H, Chodosh J, Mehta JS, Ting DSW. Artificial intelligence for anterior segment diseases: Emerging applications in ophthalmology. Br J Ophthalmol 2021;105(2):158-168.Abstract
With the advancement of computational power, refinement of learning algorithms and architectures, and availability of big data, artificial intelligence (AI) technology, particularly with machine learning and deep learning, is paving the way for 'intelligent' healthcare systems. AI-related research in ophthalmology previously focused on the screening and diagnosis of posterior segment diseases, particularly diabetic retinopathy, age-related macular degeneration and glaucoma. There is now emerging evidence demonstrating the application of AI to the diagnosis and management of a variety of anterior segment conditions. In this review, we provide an overview of AI applications to the anterior segment addressing keratoconus, infectious keratitis, refractive surgery, corneal transplant, adult and paediatric cataracts, angle-closure glaucoma and iris tumour, and highlight important clinical considerations for adoption of AI technologies, potential integration with telemedicine and future directions.
Olsen MV, Lyngstadaas AV, Bair JA, Hodges RR, Utheim TP, Serhan CN, Dartt DA. Maresin 1, a specialized proresolving mediator, stimulates intracellular [Ca ] and secretion in conjunctival goblet cells. J Cell Physiol 2021;236(1):340-353.Abstract
Mucin secretion from conjunctival goblet cells forms the tear film mucin layer and requires regulation to function properly. Maresin 1 (MaR1) is a specialized proresolving mediator produced during the resolution of inflammation. We determined if MaR1 stimulates mucin secretion and signaling pathways used. Cultured rat conjunctival goblet cells were used to measure the increase in intracellular Ca ([Ca ] ) concentration and mucin secretion. MaR1-increased [Ca ] and secretion were blocked by inhibitors of phospholipase C, protein kinase C, Ca /calmodulin-dependent protein kinase II, and extracellular-regulated kinase 1/2. MaR1 added before addition of histamine counterregulated histamine-stimulated increase in [Ca ] and secretion. We conclude that MaR1 likely has two actions in conjunctival goblet cells: first, maintaining optimal tear film mucin levels by increasing [Ca ] and stimulating mucin secretion in health and, second, attenuating the increase in [Ca ] and overproduction of mucin secretion by counterregulating the effect of histamine as occurs in ocular allergy.
Ong Tone S, Kocaba V, Böhm M, Wylegala A, White TL, Jurkunas UV. Fuchs endothelial corneal dystrophy: The vicious cycle of Fuchs pathogenesis. Prog Retin Eye Res 2021;80:100863.Abstract
Fuchs endothelial corneal dystrophy (FECD) is the most common primary corneal endothelial dystrophy and the leading indication for corneal transplantation worldwide. FECD is characterized by the progressive decline of corneal endothelial cells (CECs) and the formation of extracellular matrix (ECM) excrescences in Descemet's membrane (DM), called guttae, that lead to corneal edema and loss of vision. FECD typically manifests in the fifth decades of life and has a greater incidence in women. FECD is a complex and heterogeneous genetic disease where interaction between genetic and environmental factors results in cellular apoptosis and aberrant ECM deposition. In this review, we will discuss a complex interplay of genetic, epigenetic, and exogenous factors in inciting oxidative stress, auto(mito)phagy, unfolded protein response, and mitochondrial dysfunction during CEC degeneration. Specifically, we explore the factors that influence cellular fate to undergo apoptosis, senescence, and endothelial-to-mesenchymal transition. These findings will highlight the importance of abnormal CEC-DM interactions in triggering the vicious cycle of FECD pathogenesis. We will also review clinical characteristics, diagnostic tools, and current medical and surgical management options for FECD patients. These new paradigms in FECD pathogenesis present an opportunity to develop novel therapeutics for the treatment of FECD.
Wang Y, Carreno-Galeano JT, Singh RB, Dana R, Yin J. Long-term Outcomes of Punctal Cauterization in the Management of Ocular Surface Diseases. Cornea 2021;40(2):168-171.Abstract
PURPOSE: To evaluate the long-term outcomes of surgical occlusion of lacrimal puncta using thermal cautery in the management of ocular surface diseases. METHODS: We reviewed medical records of 80 consecutive patients from a single academic center who underwent punctal cauterization. Patient demographics, ocular history, symptoms, and signs of ocular surface diseases pre- and post-cauterization were recorded. RESULTS: A total of 80 patients (171 puncta) were included, with an average age of 59 years and a follow-up duration of 27 months. The most common ocular morbidity was ocular graft-versus-host disease (n = 36), followed by primary keratoconjunctivitis sicca (n = 15). Indications for punctal cauterization included plug loss (n = 51), difficulty in plug fitting (n = 11), plug-related complications (n = 6), recanalization of previous cauterization (n = 7), and severe ocular surface disease requiring permanent punctal closure (n = 4). After punctal cauterization, the percentage of eyes with severe (21%) and moderate (25%) dry eye decreased significantly (8% and 19% at 3 months and 6% and 17% at 12 months, P = 0.0006). Fifty-four percent of patients reported improvement in their symptoms. The rate of recanalization was 21% during the follow-up period. The use of topical corticosteroids was associated with higher recanalization rate. Associated complications were limited to temporary pain and swelling. CONCLUSIONS: Punctal cauterization is an effective modality in treating severe ocular surface diseases in patients who repeatedly lose punctal plugs, and it can be easily performed in a clinic setting without major complications. However, cauterization may need to be repeated in up to a quarter of cases because of recanalization.
Chen Y, Shao C, Fan N-W, Nakao T, Amouzegar A, Chauhan SK, Dana R. The functions of IL-23 and IL-2 on driving autoimmune effector T-helper 17 cells into the memory pool in dry eye disease. Mucosal Immunol 2021;14(1):177-186.Abstract
Long-lived memory T-helper 17 (Th17) cells actively mediate the chronic inflammation in autoimmune disorders, including dry eye disease (DED). The mechanisms responsible for the maintenance and reactivation of these cells in autoimmunity have been subject of investigation. However, the process through which memory Th17 are generated from their effector precursors remains to be elucidated. Herein, using our murine model of DED, we detect a linear transition from effector-to-memory Th17 cells during the abatement phase of acute inflammation, which is accompanied by persistently high levels of IL-23 and diminished levels of IL-2. In addition, in vitro culture of effector Th17 cells derived from the DED animals with IL-23, but not IL-2, leads to significant generation of memory Th17 cells, along with upregulated expression levels of IL-7R and IL-15R by these cells. Furthermore, supplementation of IL-2 abolishes and blockade of IL-2 enhances IL-23-induced generation of memory Th17 cells in vitro. Finally, in vivo blockade of IL-23 signaling during the contraction phase of primary response inhibits the generation of memory Th17 cells from their effector precursors. Together, our data demonstrate a new dichotomy between IL-23 and IL-2 in driving effector Th17 cells into the memory pool in autoimmune-mediated ocular surface inflammation.
Tsubota K, Pflugfelder SC, Liu Z, Baudouin C, Kim HM, Messmer EM, Kruse F, Liang L, Carreno-Galeano JT, Rolando M, Yokoi N, Kinoshita S, Dana R. Defining Dry Eye from a Clinical Perspective. Int J Mol Sci 2020;21(23)Abstract
Over the past decades, the number of patients with dry eye disease (DED) has increased dramatically. The incidence of DED is higher in Asia than in Europe and North America, suggesting the involvement of cultural or racial factors in DED etiology. Although many definitions of DED have been used, discrepancies exist between the various definitions of dry eye disease (DED) used across the globe. This article presents a clinical consensus on the definition of DED, as formulated in four meetings with global DED experts. The proposed new definition is as follows: "Dry eye is a multifactorial disease characterized by a persistently unstable and/or deficient tear film (TF) causing discomfort and/or visual impairment, accompanied by variable degrees of ocular surface epitheliopathy, inflammation and neurosensory abnormalities." The key criteria for the diagnosis of DED are unstable TF, inflammation, ocular discomfort and visual impairment. This definition also recommends the assessment of ocular surface epitheliopathy and neurosensory abnormalities in each patient with suspected DED. It is easily applicable in clinical practice and should help practitioners diagnose DED consistently. This consensus definition of DED should also help to guide research and clinical trials that, to date, have been hampered by the lack of an established surrogate endpoint.
McKay TB, Guo X, Hutcheon AEK, Karamichos D, Ciolino JB. Methods for Investigating Corneal Cell Interactions and Extracellular Vesicles In Vitro. Curr Protoc Cell Biol 2020;89(1):e114.Abstract
Science and medicine have become increasingly "human-centric" over the years. A growing shift away from the use of animals in basic research has led to the development of sophisticated in vitro models of various tissues utilizing human-derived cells to study physiology and disease. The human cornea has likewise been modeled in vitro using primary cells derived from corneas obtained from cadavers or post-transplantation. By utilizing a cell's intrinsic ability to maintain its tissue phenotype in a pre-designed microenvironment containing the required growth factors, physiological temperature, and humidity, tissue-engineered corneas can be grown and maintained in culture for relatively long periods of time on the scale of weeks to months. Due to its transparency and avascularity, the cornea is an optimal tissue for studies of extracellular matrix and cell-cell interactions, toxicology and permeability of drugs, and underlying mechanisms of scarring and tissue regeneration. This paper describes methods for the cultivation of corneal keratocytes, fibroblasts, epithelial, and endothelial cells for in vitro applications. We also provide detailed, step-by-step protocols for assembling and culturing 3D constructs of the corneal stroma, epithelial- and endothelial-stromal co-cultures and isolation of extracellular vesicles. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Isolating and culturing human corneal keratocytes and fibroblasts Basic Protocol 2: Isolating and culturing human corneal epithelial cells Basic Protocol 3: Isolating and culturing human corneal endothelial cells Basic Protocol 4: 3D corneal stromal construct assembly Basic Protocol 5: 3D corneal epithelial-stromal construct assembly Basic Protocol 6: 3D corneal endothelial-stromal construct assembly Basic Protocol 7: Isolating extracellular vesicles from corneal cell conditioned medium Support Protocol: Cryopreserving human corneal fibroblasts, corneal epithelial cells, and corneal endothelial cells.
Gonzalez-Andrades M, Jalimarada SS, Rodriguez-Benavente M, Feeley MN, Woodward AM, AbuSamra DB, Argüeso P. Golgi α1,2-mannosidase I induces clustering and compartmentalization of CD147 during epithelial cell migration. Cell Adh Migr 2020;14(1):96-105.Abstract
CD147 is a widely expressed matrix metalloproteinase inducer involved in the regulation of cell migration. The high glycosylation and ability to undergo oligomerization have been linked to CD147 function, yet there is limited understanding on the molecular mechanisms behind these processes. The current study demonstrates that the expression of Golgi α1,2-mannosidase I is key to maintaining the cell surface organization of CD147 during cell migration. Using an in vitro model of stratified human corneal epithelial wound healing, we show that CD147 is clustered within lateral plasma membranes at the leading edge of adjacent migrating cells. This localization correlates with a surge in matrix metalloproteinase activity and an increase in the expression of α1,2-mannosidase subtype IC (MAN1C1). Global inhibition of α1,2-mannosidase I activity with deoxymannojirimycin markedly attenuates the glycosylation of CD147 and disrupts its surface distribution at the leading edge, concomitantly reducing the expression of matrix metalloproteinase-9. Likewise, treatment with deoxymannojirimycin or siRNA-mediated knockdown of MAN1C1 impairs the ability of the carbohydrate-binding protein galectin-3 to stimulate CD147 clustering in unwounded cells. We conclude that the mannose-trimming activity of α1,2-mannosidase I coordinates the clustering and compartmentalization of CD147 that follows an epithelial injury.
Hui P-C, Pereira LA, Dore R, Chen S, Taniguchi E, Chodosh J, Dohlman CH, Paschalis EI. Intrinsic Optical Properties of Boston Keratoprosthesis. Transl Vis Sci Technol 2020;9(12):10.Abstract
Purpose: To benchmark the optical performance of Boston Keratoprosthesis (B-KPro). Methods: Back focal lengths (BFL) of B-KPros for various eye axial lengths were measured using an optical bench, International Organization for Standardization-certified for intraocular lens characterization, and compared against manufacturer's specification. The modulation transfer function (MTF) and the resolution efficiencies were measured. The theoretical geometry-dependent higher-order aberrations (HOA) were calculated. The devices were characterized with optical profilometry for estimating the surface scattering. Aberration correction and subsequent image quality improvement were simulated in CODE-V. Natural scene-imaging was performed in a mock ocular environment. Retrospective analysis of 15 B-KPro recipient eyes were presented to evaluate the possibility of achieving 20/20 best-corrected visual acuity (BCVA). Results: BFL measurements were in excellent agreement with the manufacturer-reported values (r = 0.999). The MTF specification exceeded what is required for achieving 20/20 visual acuity. Astigmatism and field curvature, correctable in simulations, were the primary aberrations limiting imaging performance. Profilometry of the anterior surface revealed nanoscale roughness (root-mean-square amplitude, 30-50 nm), contributing negligibly to optical scattering. Images of natural scenes obtained with a simulated B-KPro eye demonstrated good central vision, with 10/10 visual acuity (equivalent to 20/20). Full restoration of 20/20 BCVA was obtainable for over 9 years in some patients. Conclusions: Theoretical and experimental considerations demonstrate that B-KPro has the optical capacity to restore 20/20 BCVA in patients. Further image quality improvement can be anticipated through correction of HOAs. Translational Relevance: We establish an objective benchmark to characterize the optics of the B-KPro and other keratoprosthesis and propose design changes to allow improved vision in B-KPro patients.
Tellefsen S, Badian RA, Utheim TP, Utheim ØA, Stojanovic A, Tashbayev B, Raeder S, Dartt DA, Chen X. Sex and age differences in symptoms and signs of dry eye disease in a Norwegian cohort of patients. Ocul Surf 2020;Abstract
PURPOSE: To investigate sex and age differences in symptoms and signs in a Norwegian clinic-based cohort of patients with dry eye disease (DED). METHODS: Visitors at the Norwegian Dry Eye Clinic were examined using Ocular Surface Disease Index (OSDI) questionnaire score, tear osmolarity, tear break-up time (TFBUT), ocular surface staining, corneal sensitivity, Schirmer I test, and meibum expressibility (ME) and quality (MQ). A diagnosis of DED was made by an ophthalmologist based on symptoms and signs, and only DED patients were enrolled in the study: 1823 patients (338 males; mean age 51.2 ± 16.2 years; 1485 females; mean age 52.5 ± 16.0 years). The patients were divided into age subgroups: 20-39 years, 40-59 years and ≥60 years. Sex differences in the aforementioned tests were analyzed. Values were reported as mean ± standard deviation (SD), and intergroup comparisons were performed using Mann-Whitney U test. Multiple regression was used to analyze sex and age influences on symptoms and signs. RESULTS: When patients of all ages were analyzed, females had increased osmolarity, shorter TFBUT, reduced MQ and ME and higher corneal sensitivity. OSDI, Schirmer I test, ocular surface staining and corneal staining were not significantly different between the sexes. Only with TFBUT and ME were the sex difference present in all age subgroups. Multiple regression showed that all parameters were influenced by either sex or age, but only TFBUT and ME were influenced by both sex and age. (all p < 0.05). CONCLUSIONS: Sex and age differences in dry eye were most consistent in TFBUT and ME, that indicate differences in meibomian gland functionality. Sex and age subgroup stratification is important in future studies investigating DED in other populations.
Venkateswaran N, Klavdianou O, Kondylis G, Kosmidis I, Palioura S. Paraneoplastic Pemphigus Associated with Bilateral Corneal Perforations in Follicular Dendritic Cell Sarcoma. Ocul Immunol Inflamm 2020;:1-3.Abstract
PURPOSE: To describe a case of paraneoplastic pemphigus (PNP) presenting as spontaneous bilateral corneal perforations in a patient with follicular dendritic cell sarcoma. METHODS: Retrospective chart review Results: A 73-year-old Greek woman with a history of follicular dendritic cell sarcoma (FDCS) presented with bilateral corneal perforations and a cicatrizing conjunctivitis. Her diagnosis was consistent with PNP with corneal and conjunctival involvement after a change in her chemotherapy regimen from intravenous cyclophosphamide to gemcitabine. She was treated with a multilayered amniotic membrane in the right eye and cyanoacrylate glue in the left eye. Systemic intravenous cyclophosphamide and oral prednisone were re-started. Both perforations healed but the patient passed away soon after precluding further follow-up. CONCLUSIONS: Ocular manifestations of PNP can rarely present with spontaneous corneal perforations. This is the first case of FDCS-associated PNP with corneal involvement. Such cases should be diagnosed expediently and managed with aggressive systemic immunosuppressive therapy.
Ramier A, Eltony AM, Chen YT, Clouser F, Birkenfeld JS, Watts A, Yun S-H. In vivo measurement of shear modulus of the human cornea using optical coherence elastography. Sci Rep 2020;10(1):17366.Abstract
Corneal stiffness plays a critical role in shaping the cornea with respect to intraocular pressure and physical interventions. However, it remains difficult to measure the mechanical properties noninvasively. Here, we report the first measurement of shear modulus in human corneas in vivo using optical coherence elastography (OCE) based on surface elastic waves. In a pilot study of 12 healthy subjects aged between 25 and 67, the Rayleigh-wave speed was 7.86 ± 0.75 m/s, corresponding to a shear modulus of 72 ± 14 kPa. Our data reveal two unexpected trends: no correlation was found between the wave speed and IOP between 13-18 mmHg, and shear modulus decreases with age (- 0.32 ± 0.17 m/s per decade). We propose that shear stiffness is governed by the interfibrillar matrix, whereas tensile strength is dominated by collagen fibrils. Rayleigh-wave OCE may prove useful for clinical diagnosis, refractive surgeries, and treatment monitoring.
Jamali A, Hu K, Sendra VG, Blanco T, Lopez MJ, Ortiz G, Qazi Y, Zheng L, Turhan A, Harris DL, Hamrah P. Characterization of Resident Corneal Plasmacytoid Dendritic Cells and Their Pivotal Role in Herpes Simplex Keratitis. Cell Rep 2020;32(9):108099.Abstract
The presence and potential functions of resident plasmacytoid dendritic cells (pDCs) in peripheral tissues is unclear. We report that pDCs constitutively populate naïve corneas and are increased during sterile injuries or acute herpes simplex virus 1 (HSV-1) keratitis. Their local depletion leads to severe clinical disease, nerve loss, viral dissemination to the trigeminal ganglion and draining lymph nodes, and mortality, while their local adoptive transfer limits disease. pDCs are the main source of HSV-1-induced IFN-α in the corneal stroma through TLR9, and they prevent re-programming of regulatory T cells (Tregs) to effector ex-Tregs. Clinical signs of infection are observed in pDC-depleted corneas, but not in pDC-sufficient corneas, following low-dose HSV-1 inoculation, suggesting their critical role in corneal antiviral immunity. Our findings demonstrate a vital role for corneal pDCs in the control of local viral infections.
Xu L-J, Rong S-S, Xu Y-S, Zheng L-B, Qiu W-Y, Zhang X, Jiang L-J, Duan R-P, Tian T, Yao Y-F. Anti-fibrosis potential of pirarubicin via inducing apoptotic and autophagic cell death in rabbit conjunctiva. Exp Eye Res 2020;200:108215.Abstract
This study investigated the potential efficacy of pirarubicin (THP) in modulating rabbit conjunctival fibrosis both in vitro and in vivo and characterized the underlying mechanisms. Primary rabbit conjunctival fibroblasts (RCF) were cultured and treated with THP or mitomycin C (MMC) for 5 min, followed by assaying for cell viability, cell cycle distribution, apoptotic and autophagic pathways. The production of reactive oxygen species (ROS) and chemotaxis of macrophages by RCF were evaluated using 2',7'-dichlorofluorescein diacetate (DCFH-DA) labeling and transwell migration assay, respectively. Limbal stem cell excision in combination with alkali burn was performed on the rabbits to establish a model of limbal deficiency and conjunctival fibro-vascular invasion. After three months, the modeled fibro-vascular tissue was excised combined with topical subconjunctival 5-min exposure to THP compared with MMC intraoperatively. The recurrence of postoperative fibrosis and the expression of apoptosis, autophagy, and inflammation markers were evaluated by immunohistochemistry. All modeled rabbits developed conjunctival fibro-vascular lesions, which were similar to human recurrent pterygium (HRP). Both THP and MMC inhibited RCF proliferation and arrested cell cycle at the G0/G1 phase. In particular, 7.5 μmol/L THP remarkably promoted RCF autophagy by upregulating the levels of Beclin 1, Atg 5/12 conjugate, and LC3B, whereas, 15 μmol/L THP significantly triggered a cascade of mitochondrial-associated RCF apoptosis. THP induced the production of ROS and enhanced the chemoattraction of macrophages by RCF. Similar to 600 μmol/L MMC, both 7.5 μmol/L and 15 μmol/L THP attenuated postoperative conjunctival fibrosis in the models; 7.5 μmol/L THP preferentially enhanced autophagy while causing fewer side effects. THP exerted its antifibrotic action by modulating autophagy in RCF, inducing cell cycle arrest, and mitochondrial-mediated apoptosis. THP at the dose of 7.5 μmol/L prevented postoperative conjunctival fibrosis in an animal model.
Hayashi T, Yasutsugu I, Shimizu T, Kuroki T, Kobashigawa Y, Iijima Y, Yuda K. Pars plana vitrectomy combined with penetrating keratoplasty and transscleral-sutured intraocular lens implantation in complex eyes: a case series. BMC Ophthalmol 2020;20(1):369.Abstract
BACKGROUND: The aim of this study was to evaluate the clinical outcomes of pars plana vitrectomy (PPV) combined with penetrating keratoplasty (PKP) and transscleral-sutured intraocular lens (IOL) implantation (IOL-suture) in complex eyes. METHODS: In this prospective, consecutive interventional case series, patients who underwent PKP combined with PPV and IOL implantation from July 2014 to March 2018 at Yokohama Minami Kyosai Hospital were enrolled. The postoperative best corrected visual acuity (BCVA) (converted to logarithm of the minimal angle of resolution [logMAR] units), intraocular pressure (IOP, mmHg), endothelial cell density (ECD, cells/mm), graft survival, complications, astigmatism, and spherical equivalent (dioptres [D]) were evaluated. RESULTS: This study included 11 eyes of 11 patients (three females and eight males; mean age, 61.8 ± 13.9 years) with an injury (n = 6) or bullous keratopathy (n = 5). The BCVA significantly improved from 1.50 ± 0.66 logMAR preoperatively to 0.78 ± 0.59 logMAR (p < 0.001) postoperatively. The baseline ECD significantly decreased from 2396 ± 238 cells/mm preoperatively to 1132 ± 323 cells/mm (p < 0.001) postoperatively. Despite two rejection episodes, graft survival rates were 100%. The mean follow-up period was 38.0 ± 20.5 months. Two patients required combined glaucoma surgery, and three patients underwent subsequent glaucoma surgery. Postoperative astigmatism and spherical equivalent were 3.9 ± 3.2 D and 0.29 ± 2.18 D, respectively. CONCLUSION: The combination of PKP, PPV, and IOL-suture implantation could be a safe and effective approach for eyes requiring anterior segment surgery; however, these eyes are associated with a higher incidence of glaucoma surgery.

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