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Vernal keratoconjunctivitis (VKC) is a chronic severe ocular allergic inflammation mostly observed in children and young adults. The ocular manifestations are the expression of multifactorial immune mechanisms that generally have a good prognosis, however long-term inflammation may remarkably reduce the visual function due to complications and poor therapeutic responses. Lack of responsiveness to a drug or treatment is relatively common in VKC and it is not only due to corneal involvement, which is considered the main sign of severity. The concept of refractory may be relative to multiple factors including the clinical condition, systemic co-morbidities, previous or concomitant drugs or regiments, compliance, patient's psychological condition or expectations, type of exposome and environmental conditions, doctor's experience and expectations, or timing of clinical evaluation. In this narrative review, the authors propose a definition of refractory VKC based on revised literature and clinical experience and consider potential new treatments for refractory patients and surgical management in case of complications.
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PURPOSE OF REVIEW: Ocular surface disorders (OSDs) are a prevalent and often debilitating condition encountered in clinical practice, particularly by allergists and clinical immunologists. RECENT FINDINGS: A comprehensive guide to office procedures for evaluating and managing OSDs, with a specific focus on ocular allergies, would assist in the evaluation process that begins with an initial patient assessment utilizing standardized forms to systematically gather detailed medical history, symptomatology, and environmental exposure data. This structured approach ensures a thorough understanding of the patient's condition and facilitates targeted interventions. In addition to allergy testing, the assessment of the tear film is essential for a comprehensive evaluation of OSDs. The Schirmer test is employed to quantify tear production, providing objective data on tear film adequacy and guiding interventions for tear film deficiencies. SUMMARY: This multifaceted diagnostic approach ensures that all contributing factors to OSDs are identified and appropriately managed. By integrating these office procedures, allergists and clinical immunologists can enhance their diagnostic accuracy and therapeutic efficacy, ultimately improving patient outcomes. This manuscript provides a practical resource, outlining some of the methodologies and clinical applications of each procedure, and highlighting their role in the holistic management of OSDs in allergic patients.
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Blau syndrome (BS) is a rare autoinflammatory granulomatosis characterized by granulomatous arthritis, uveitis, and dermatitis. Ocular complications are particularly severe in BS, significantly contributing to morbidity. This study aims to identify potential biomarkers for BS ocular degeneration through proteomic profiling of tear samples from affected patients. Seven subjects from the same family, including four carriers of the BS-associated NOD2 mutation (p.E383K), were recruited alongside healthy controls. Tear samples were collected using Schirmer strips and analyzed via mass spectrometry. A total of 387 proteins were identified, with significant differences in protein expression between BS patients, healthy familial subjects, and healthy controls. Key findings include the overexpression of alpha-2-macroglobulin (A2M) and immunoglobulin heavy constant gamma 4 (IGHG4) in BS patients. Bioinformatic analysis revealed that differentially expressed proteins are involved in acute-phase response, extracellular exosome formation, and protein binding. Notably, neutrophils' azurophilic granule components, as azurocidin (AZU1), myeloperoxidases (MPO), and defensins (DEFA3), were highly expressed in the most severely affected subject, suggesting a potential role of neutrophils in BS ocular severity. These proteins might be promising biomarkers for ocular involvement in BS, facilitating early detection and tailored treatment strategies.
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Artritis , Biomarcadores , Proteómica , Sarcoidosis , Sinovitis , Lágrimas , Uveítis , Humanos , Lágrimas/metabolismo , Biomarcadores/metabolismo , Uveítis/metabolismo , Uveítis/genética , Uveítis/diagnóstico , Femenino , Masculino , Artritis/genética , Artritis/metabolismo , Sinovitis/metabolismo , Sinovitis/genética , Sarcoidosis/genética , Sarcoidosis/metabolismo , Adulto , Proteómica/métodos , Proteína Adaptadora de Señalización NOD2/genética , Proteína Adaptadora de Señalización NOD2/metabolismo , Persona de Mediana Edad , Mutación , Proteoma/metabolismo , Enfermedades Autoinflamatorias HereditariasRESUMEN
PURPOSE OF REVIEW: The aim of this review, is to present an updated revision of topical management of SAC and PAC, based on the available scientific evidence and focused on the impact of ophthalmic solution formulations on eye surface. RECENT FINDINGS: Physicians treating ocular allergy should be aware of tear film and tear film disruption in SAC and PAC, and how eye drop composition and additives affect the physiology of the allergic eye. Seasonal and perennial allergic conjunctivitis (SAC and PAC) are the most frequent causes of ocular allergy (OA), and both conditions are underdiagnosed and undertreated. SAC and PAC are immunoglobulin E (IgE)-mediated hypersensitivity reactions. The additional tear film disruption caused by the release of inflammatory mediators increases and exacerbates the impact of signs and symptoms and may trigger damage of the ocular surface. Comorbidities are frequent, and dry eye disease in particular must be considered. Clinical guidelines for the management of SAC and PAC recommend topical therapy with antihistamines, mast cells stabilizers or dualaction agents as first-line treatment, but care should be taken, as many medications contain other compounds that may contribute to ocular surface damage.
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Conjuntivitis Alérgica , Soluciones Oftálmicas , Humanos , Conjuntivitis Alérgica/tratamiento farmacológico , Conjuntivitis Alérgica/inmunología , Soluciones Oftálmicas/uso terapéutico , Antagonistas de los Receptores Histamínicos/uso terapéutico , LágrimasRESUMEN
Purpose: Vernal keratoconjunctivitis (VKC) is an ocular allergic disease characterized by a type 2 inflammation, tissue remodeling, and low quality of life for the affected patients. We investigated the involvement of endoplasmic reticulum (ER) stress and unfolded protein response in VKC. Methods: Conjunctival imprints from VKC patients and normal subjects (CTs) were collected, and RNA was isolated, reverse transcribed, and analyzed with the Affymetrix microarray. Differentially expressed genes between VKC patients and CTs were evaluated. Genes related to ER stress, apoptosis, and autophagy were further considered. VKC and CT conjunctival biopsies were analyzed by immunohistochemistry (IHC) with specific antibodies against unfolded protein response (UPR), apoptosis, and inflammation. Conjunctival fibroblast and epithelial cell cultures were exposed to the conditioned medium of activated U937 monocytes and analyzed by quantitative PCR for the expression of UPR, apoptosis, autophagy, and inflammatory markers. Results: ER chaperones HSPA5 (GRP78/BiP) and HYOU1 (GRP170) were upregulated in VKC patients compared to CTs. Genes encoding for ER transmembrane proteins, PKR-like ER kinase (PERK), activating transcription factor 6 (ATF6), ER-associated degradation (ERAD), and autophagy were upregulated, but not those related to apoptosis. Increased positive reactivity of BiP and ATF6 and unchanged expression of apoptosis markers were confirmed by IHC. Cell cultures in stress conditions showed an overexpression of UPR, proinflammatory, apoptosis, and autophagy markers. Conclusions: A significant overexpression of genes encoding for ER stress, UPR, and pro-inflammatory pathway components was reported for VKC. Even though these pathways may lead to ER homeostasis, apoptosis, or inflammation, ER stress in VKC may predominantly contribute to promote inflammation.
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Conjuntivitis Alérgica , Humanos , Conjuntivitis Alérgica/genética , Calidad de Vida , Respuesta de Proteína Desplegada , Estrés del Retículo Endoplásmico/genética , Inflamación , Conjuntiva , Chaperón BiP del Retículo EndoplásmicoRESUMEN
Vernal keratoconjunctivitis (VKC) is a serious eye allergy characterized by poorly understood pathogenic mechanisms and a lack of effective treatments. Autophagy, a process involved in both triggering and suppressing immune and inflammatory responses, plays a role in VKC's pathophysiology. Understanding autophagy's involvement in VKC could lead to new treatment possibilities, such as utilizing specific topical substances to induce or inhibit autophagy and prevent severe complications of this eye condition. In our current protocol, we present a robust methodology established in our laboratory for studying autophagy in primary conjunctival fibroblasts. We assess autophagy through techniques like immunocytochemistry, immunoblotting, and qPCR.
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PURPOSE: To evaluate the quality of life (QoL), mental health conditions and corneal morphology in neuropathic corneal pain (NCP) subjects without a significant ocular surface disease. METHODS: A composite questionnaire was administered to 228 consecutive subjects, assessing the pain intensity, duration, and quality using a modified version of the Self-Administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) and Pain Detect (PD) questionnaires. Subjects diagnosed with possible central NCP and two sub-groups of patients diagnosed with peripheral ocular pain completed an additional battery of mental health questionnaires and were examined by In Vivo Confocal Microscopy (IVCM). RESULTS: Of the 76 subjects that reported chronic ocular pain (duration >1 month), 53 were classified with probable NCP. Nine subjects without signs that justify the pain and non-responding to topical anaesthesia, were considered affected by central NCP. In these patients, a significant negative correlation was found between the presence pain and the mental component of the QoL (R2 = 0.733), and a positive correlation between the severity of pain the presence post-traumatic stress disorder (R2 = 0.83) and depression (R2 = 0.93). Although neuromas and sprouting had higher frequency in the central NCP group compared the control groups, these differences was not statistically different. CONCLUSIONS: The assessment of ocular pain characteristics using multiple questionnaires and IVCM may help to recognize differences between nociceptive and neuropathic pain. An association between pain intensity and mental health condition may guide the therapeutical choices.
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Enfermedades de la Córnea , Neuralgia , Humanos , Calidad de Vida , Depresión/complicaciones , Encuestas y Cuestionarios , Córnea/inervación , Enfermedades de la Córnea/complicaciones , Enfermedades de la Córnea/diagnóstico , Neuralgia/diagnóstico , Dolor Ocular/diagnóstico , Dolor Ocular/etiologíaRESUMEN
Background: There is increasing evidence of autophagy activation in COPD, but its role is complex and probably regulated through cell type-specific mechanisms. This study aims to investigate the autophagic process at multiple levels within the respiratory system, using different methods to clarify conflicting results reported so far. Methods: This cross-sectional study was performed on bronchial biopsies and peripheral lung samples obtained from COPD patients (30 and 12 per sample type, respectively) and healthy controls (25 and 22 per sample type, respectively), divided by smoking history. Subjects were matched for age and smoking history. We analysed some of the most important proteins involved in autophagosome formation, such as LC3 and p62, as well as some molecules essential for lysosome function, such as lysosome-associated membrane protein 1 (LAMP1). Immunohistochemistry was used to assess the autophagic process in both sample types. ELISA and transcriptomic analysis were performed on lung samples. Results: We found increased autophagic stimulus in smoking subjects, regardless of respiratory function. This was revealed by immunohistochemistry through a significant increase in LC3 (p<0.01) and LAMP1 (p<0.01) in small airway bronchiolar epithelium, alveolar septa and alveolar macrophages. Similar results were obtained in bronchial biopsy epithelium by evaluating LC3B (p<0.05), also increased in homogenate lung tissue using ELISA (p<0.05). Patients with COPD, unlike the others, showed an increase in p62 by ELISA (p<0.05). No differences were found in transcriptomics analysis. Conclusions: Different techniques, applied at post-transcriptional level, confirm that cigarette smoke stimulates autophagy at multiple levels inside the respiratory system, and that autophagy failure may characterise COPD.
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PURPOSE: This study evaluates the efficacy and tolerability of cyclosporine A cationic emulsion (CsA-CE) in patients ≥4 years of age with moderate-to-severe vernal keratoconjunctivitis (VKC). METHODS: This Phase II/III, multicenter, double-masked, dose-ranging study had 2 treatment periods: a 4-week, randomized, vehicle-controlled period in which patients received 0.05% CsA-CE, 0.1% CsA-CE, or vehicle eye drops 4 times daily (period 1) and a 3-month period in which patients received 0.05% CsA-CE or 0.1% CsA-CE 2 or 4 times daily (period 2). The primary efficacy end point was rating of subjective symptoms at day 28 in period 1 per the BenEzra scale. FINDINGS: All groups showed improvement in subjective VKC symptoms at day 28, without a statistically significant difference between 0.05% or 0.1% CsA-CE vs vehicle. Both CsA-CE doses produced statistically significant improvements in corneal fluorescein staining scores vs vehicle at day 28; improvements were evident as early as week 1 and continued through month 1. Progressive reduction in subjective itching was evident after week 1 and continued through month 1. Treatment for an additional 3 months further improved subjective symptoms and objective signs of VKC in both CsA-CE groups. Improvement was most notable with 0.1% CsA-CE in patients with severe keratitis. The safety and tolerability profile is favorable. IMPLICATIONS: Although treatment with 0.05% and 0.1% CsA-CE showed clinical efficacy in alleviating keratitis and itching as early as week 1, with sustained benefit through 1 month, the primary efficacy end point was not met. These findings informed the design of the Phase III trial of 0.1% CsA-CE (Vernal Keratoconjunctivitis Study). CLINICALTRIALS: gov identifier: NCT00328653.
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Conjuntivitis Alérgica , Ciclosporina , Queratitis , Humanos , Conjuntivitis Alérgica/tratamiento farmacológico , Ciclosporina/uso terapéutico , Método Doble Ciego , Emulsiones/uso terapéutico , Queratitis/tratamiento farmacológico , Soluciones Oftálmicas/uso terapéutico , Prurito , Resultado del TratamientoRESUMEN
PURPOSE OF REVIEW: Chronic ocular allergies, vernal (VKC) and atopic keratoconjunctivitis (AKC) are relatively rare conditions that require definite diagnostic criteria to the most appropriate therapeutical approach. RECENT FINDINGS: The diagnosis of both VKC and AKC is generally based on clinical history, signs and symptoms, and the results of allergic tests, which allow to identify the different diseases phenotypes. However, other subtypes of the two diseases and/or overlaps may occur making the diagnosis non always so clear, such as VKC and AKC overlaps or adult-like VKC disease. Each of these phenotypes may be sustained by different mechanisms which are still not well defined but not only related to a type 2 inflammation. The further challenges will be to correlate clinical or molecular biomarkers to a single subtype or disease severity. SUMMARY: Definite criteria of chronic allergies will further guide to more specific therapeutical approaches.
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Conjuntivitis Alérgica , Queratoconjuntivitis , Humanos , Conjuntivitis Alérgica/diagnóstico , Queratoconjuntivitis/diagnóstico , Ojo , BiomarcadoresRESUMEN
Introduction: Keratoconus (KC) is an ocular disorder with a multifactorial origin. Transcriptomic analyses (RNA-seq) revealed deregulations of coding (mRNA) and non-coding RNAs (ncRNAs) in KC, suggesting that mRNA-ncRNA co-regulations can promote the onset of KC. The present study investigates the modulation of RNA editing mediated by the adenosine deaminase acting on dsRNA (ADAR) enzyme in KC. Materials: The level of ADAR-mediated RNA editing in KC and healthy corneas were determined by two indexes in two different sequencing datasets. REDIportal was used to localize known editing sites, whereas new putative sites were de novo identified in the most extended dataset only and their possible impact was evaluated. Western Blot analysis was used to measure the level of ADAR1 in the cornea from independent samples. Results: KC was characterized by a statistically significant lower RNA-editing level compared to controls, resulting in a lower editing frequency, and less edited bases. The distribution of the editing sites along the human genome showed considerable differences between groups, particularly relevant in the chromosome 12 regions encoding for Keratin type II cluster. A total of 32 recoding sites were characterized, 17 representing novel sites. JUP, KRT17, KRT76, and KRT79 were edited with higher frequencies in KC than in controls, whereas BLCAP, COG3, KRT1, KRT75, and RRNAD1 were less edited. Both gene expression and protein levels of ADAR1 appeared not regulated between diseased and controls. Conclusions: Our findings demonstrated an altered RNA-editing in KC possibly linked to the peculiar cellular conditions. The functional implications should be further investigated.
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Queratocono , Transcriptoma , Humanos , Transcriptoma/genética , Queratinas/metabolismo , Queratocono/genética , Edición de ARN/genética , ARN/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Genómica , Adenosina Desaminasa/genética , Adenosina Desaminasa/metabolismoRESUMEN
INTRODUCTION: Vernal keratoconjunctivitis (VKC) is a rare, severe allergic ocular disease, typically occurring in children and adolescents, that can have a significant impact on quality of life and lead to visual impairment. Long-term treatment may be necessary to tackle chronic inflammation and topical corticosteroid dependency must be minimised due to the risk of complications. There is a need for unified clinical guidance to aid the assessment, diagnosis and management of VKC across Europe. The aim of this expert panel (the EUR-VKC Group) was to provide clear guidance for primary care physicians and general ophthalmologists involved in the diagnosis and management of VKC. METHODS: An expert group of seven European ophthalmologists was convened and a modified nominal group technique used to develop key recommendations on VKC management. The recommendations were subject to up to two rounds of voting using a 5-point Likert scale to ascertain consensus and the strength of each recommendation. Consensus was set at a predetermined threshold of ≥ 75.0% of experts selecting 'Strongly agree' or 'Agree'. RESULTS: A total of 47 recommendations were developed relating to the assessment of key of VKC, guidance on who and when to refer, as well as treatment-escalation pathways, long-term follow-up, and supportive care and education. All recommendations reached consensus after two rounds. The group emphasise how timely diagnosis and treatment initiation that is appropriate to disease severity are crucial to benefit patients with VKC. Patients with signs ('red flags') indicating severe VKC, or persistent mild-to-moderate VKC that is non-responsive following 2-4 weeks of treatment, should be referred to a sub-specialist. CONCLUSION: The EUR-VKC Group provides recommendations on the assessment, diagnosis, management, referral and follow-up of patients with VKC. It also provides a framework to facilitate collaboration between primary care physicians, general ophthalmologists and sub-specialists to improve the outcomes for patients with VKC.
Vernal keratoconjunctivitis (VKC) is a rare, underdiagnosed, chronic allergic eye disease that typically occurs in children and adolescents. If left untreated, VKC can significantly damage the eye, potentially leading to long-term complications, visual impairment and a reduced quality of life for the child and their family and/or caregivers. In the absence of established guidelines, this consensus programme set out to gather expert insights on best practices for assessing and managing VKC across Europe. A group of seven European ophthalmologists engaged in the consensus programme. A total of 47 recommendations were developed relating to the assessment, diagnosis, management, referral and follow-up of patients with VKC. These 47 recommendations underwent two rounds of review and were revised, if necessary, following expert input. Recommendations where ≥ 75.0% of experts agreed were considered as having reached consensus and were included as final recommendations. The experts agreed that VKC can be classified as mild, moderate or severe, and should be managed according to severity in a stepwise manner, with treatment intensity escalating as the disease severity increases. Timely diagnosis and treatment initiation appropriate to the severity of VKC are crucial to prevent sight loss and improve the quality of life of children with VKC. Ongoing treatment may be necessary to tackle the chronic inflammation associated with the disease and, therefore, reliance on steroid eye drops should be reduced to avoid an increased risk of well-known complications. The experts concluded that mild VKC can be assessed and managed in primary care, but patients with severe VKC, or with moderate-to-severe VKC that does not respond to treatment within 24 weeks, should be referred to a VKC specialist.
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Vernal keratoconjunctivitis (VKC) is a severe form of ocular allergy that compromises the quality of life of affected patients. Topical cyclosporine 0.1% cationic emulsion (CsA-CE) has been recently authorized for the treatment of severe VKC. We treated 29 VKC patients with on-label CsA-CE and recorded signs and symptoms, subjective patient's treatment satisfaction and the additional use of topical corticosteroids in case of exacerbations. CsA-CE was effective in reducing signs and symptoms in daily clinical practice. The overall subjective improvement of symptoms, efficacy of the treatment, tolerability to the drug and compliance reached a high level of subjective satisfaction score.55% of treated patients required the additional use of a 3-day course of topical dexamethasone with 1.13 ± 0.81 mean courses/month. In conclusions, VKC patients reported an overall high satisfaction with used the on-label topical CsA-CE with a limited use of additional topical corticosteroid treatment.
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Conjuntivitis Alérgica , Ciclosporina , Humanos , Conjuntivitis Alérgica/diagnóstico , Conjuntivitis Alérgica/tratamiento farmacológico , Conjuntivitis Alérgica/inducido químicamente , Inmunosupresores , Calidad de Vida , Satisfacción del Paciente , Glucocorticoides/uso terapéutico , Soluciones Oftálmicas , EmulsionesRESUMEN
Dry eye disease (DED) is a chronic inflammatory disease of the ocular surface requiring long-term therapy. Severe forms of DED generally do not respond to tear substitutes alone or combined, and often require treatment with topical anti-inflammatory agents to break the vicious circle of inflammation. This review summarises data from randomised controlled trials and real-world evidence on the efficacy and safety of ciclosporin A 0.1% cationic emulsion (Ikervis®) for the management of DED. Improvements in clinical signs and symptoms were reported from as early as 4 weeks after treatment initiation, although it can take a few months to reach the full benefits. Treatment periods of up to 12 months provide sustained benefit to patients. In the most responsive patients, treatment discontinuation is possible with no further substantial relapse over 12 months in over 65% of patients. Transient local ocular effects are the most commonly reported adverse events.
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Ciclosporina , Síndromes de Ojo Seco , Humanos , Cationes/uso terapéutico , Ciclosporina/administración & dosificación , Síndromes de Ojo Seco/tratamiento farmacológico , Emulsiones , Inflamación/tratamiento farmacológico , Lágrimas , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
BACKGROUND/OBJECTIVES: Cyclosporine A cationic ophthalmic emulsion (CsA CE) was evaluated in paediatric and adolescent patients with vernal keratoconjunctivitis (VKC) in the NOVATIVE (NCT00328653) and VEKTIS (NCT01751126) trials. The similarity of these studies permitted pooled assessment of the effect of CsA CE on corneal damage as well as safety and tolerability. SUBJECTS/METHODS: Pooled outcomes were assessed for the first 28 days of treatment. In NOVATIVE, 118 patients were randomised to 4 times daily (QID) CsA CE 0.05%, 0.1%, or vehicle eye drops. In VEKTIS, 169 patients were randomised to CsA CE 0.1% QID or twice daily (BID) or vehicle. For these analyses, treatment groups comprised: (1) pooled CsA CE 0.1% QID arms (high-dose; n = 96); (2) pooled CsA CE 0.05% QID arm from NOVATIVE and CsA CE 0.1% BID data from VEKTIS (low-dose; n = 93); and (3) pooled vehicle QID arms (vehicle; n = 98). RESULTS: Changes from baseline to day 28 (mean ± standard deviation) in corneal fluorescein staining (CFS) scores for CsA CE high-dose, low-dose, and vehicle groups were -1.6 ± 1.47 (95% CI: -0.9, -0.1; p = 0.0124 vs vehicle), -1.7 ± 1.39 (95% CI: -1.1, -0.3; p = 0.0015 vs vehicle), and -1.0 ± 1.55, respectively. Adverse events (AEs) of any type were reported in 37.5%, 34.4%, and 37.8% of the high-dose, low-dose, and vehicle groups, respectively. Most were mild or moderate in severity. CONCLUSIONS: CsA CE significantly decreased corneal damage and was safe and well tolerated in patients with VKC. These data support CSA CE as a treatment option for the management of VKC.
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Conjuntivitis Alérgica , Lesiones de la Cornea , Síndromes de Ojo Seco , Adolescente , Humanos , Niño , Ciclosporina/uso terapéutico , Inmunosupresores/uso terapéutico , Conjuntivitis Alérgica/inducido químicamente , Conjuntivitis Alérgica/tratamiento farmacológico , Emulsiones/uso terapéutico , Resultado del Tratamiento , Síndromes de Ojo Seco/tratamiento farmacológico , Método Doble Ciego , Soluciones OftálmicasRESUMEN
Dry eye disease (DED) is a highly prevalent, chronic and progressive condition that affects 5-33% of the world's adult population [...].
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Like the lung, skin, and nose, the external eye is a common target of allergic inflammation. Ocular allergy (OA) represents a collection of underestimated diseases of the eye observed in children and adults. The ocular manifestations are the expression of multifactorial immune mechanisms that generally have a good prognosis, but for a few patients, long term inflammation may remarkably reduce the visual function. Evidence suggests that other co-participant systems, including epigenetic, genetic, environmental, individual factors, sex hormones, and the central and autonomic nervous systems may influence the ocular response from distant sites. This is consistent with the concept that the eye is an organ fully integrated with the rest of the body and that the therapeutic approach should be holistic, dynamic, and personalized. For instance, androgens and estrogens binding to receptors on the ocular surface and the continuous cross-talking of neuromediators and growth factors with immune cells act to maintain the ocular surface homeostasis in response to environmental challenges. The immune system links and regulates the response of the ocular surface. Complex and incompletely understood mechanisms influence the innate and adaptive immune responses and generate different OA phenotypes and endotypes discussed in the present review.