Oxidative Stress in the Protection and Injury of the Lacrimal Gland and the Ocular Surface: are There Perspectives for Therapeutics?

Oxidative stress (OS) is a major disruption in the physiology of the lacrimal functional unit (LFU). Antioxidant enzymes have dual protective activities: antioxidant and antimicrobial activities. Peroxidases have been indistinctly used as markers of the secretory activity of the LFU and implicated in the pathophysiology, diagnosis and treatment of dry eye disease (DED), even though they comprise a large family of enzymes that includes lactoperoxidase (LPO) and glutathione peroxidase (GPO), among others. Assays to measure and correlate OS with other local LFU phenomena have methodological limitations. Studies implicate molecules and reactions involved in OS as markers of homeostasis, and other studies identify them as part of the physiopathology of diseases. Despite these conflicting concepts and observations, it is clear that OS is influential in the development of DED. Moreover, many antioxidant strategies have been proposed for its treatment, including calorie restriction to nutritional supplementation. This review offers a critical analysis of the biological mechanisms, diagnostic outcomes, drug use, dietary supplements, and life habits that implicate the influence of OS on DED.

Correlation between the presumed pterygium with dry eye and with systemic and ocular risk factors.

OBJECTIVE: To estimate the epidemiology of the pterygium and its correlation with dry eye symptoms and with the potential systemic and ocular predictors. METHODS: This study is a population-based, cross-sectional study in which random visits were made to the 600 households of 600 participants of age ≥40 years in Ribeirão Preto-SP (n=420) and Cassia dos Coqueiros-SP (n=180) in Brazil. The participants were subjected to a structured interview with a detailed questionnaire to collect information on demography and the potential risk factors. Next, random participants with pterygium (n=63) or not (n=110) were evaluated for the ocular surface changes. RESULTS: The frequency of pterygium in Ribeirão Preto was 21% (15.7% among women and 32.1% among men; p=0.0002). In Cássia dos Coqueiros, the corresponding frequency was 19.4% (17.3% among women and 25.5% among men; p=0.28). The mean age of the affected individuals was higher than that of the unaffected ones (65.6 ± 10.5 years vs. 61.2 ± 12.0 years, p=0.02). A positive correlation was noted between pterygium and any prior radiotherapy and chemotherapy (p<0.0001, for both). A higher score on corneal fluorescein and conjunctival lissamine green staining was asso ciated with pterygium (p=0.0003 and 0.0001, respectively). CONCLUSION: We noted a high frequency of pterygium in two Brazilian adult populations, mainly among the men and elderly. Ocular surface damage and a previous history of radiotherapy and/or chemotherapy were found to be associated with pterygium.

Limitations and advances in new treatments and future perspectives of corneal blindness / Limitações e avanços em novos tratamentos e perspectivas futuras na cegueira corneal

ABSTRACT This review is intended to describe the therapeutic approaches for corneal blindness, detailing the steps and elements involved in corneal wound healing. It also presents the limitations of the actual surgical and pharmacological strategies used to restore and maintain corneal transparency in terms of long-term survival and geographic coverage. In addition, we critically review the perspectives of anabolic agents, including vitamin A, hormones, growth factors, and novel promitotic and anti-inflammatory modulators, to assist corneal wound healing. We discuss the studies involving nanotechnology, gene therapy, and tissue reengineering as potential future strategies to work solely or in combination with corneal surgery to prevent or revert corneal blindness.(AU)

RESUMO O presente trabalho traz uma revisão das abordagens terapêuticas para a cegueira da córnea. O estudo detalha as etapas e os elementos envolvidos na cicatrização da córnea. Ele mostra as limitações das estratégias cirúrgicas e farmacológicas usadas para restaurar e manter a transparência da córnea em termos de sobrevida a longo prazo e alcance geográfico. As perspectivas dos agentes anabólicos, incluindo vitamina A, hormônios, fatores de crescimento e novos moduladores pró-mitóticos e anti-inflamatórios para auxiliar a cicatrização da ferida na córnea, são revisadas criticamente. Aqui, apresentamos estudos envolvendo nanotecnologia, terapia gênica e reengenharia de tecidos como possíveis estratégias futuras para atuar de maneira isolada ou combinada com a cirurgia da córnea para prevenir ou reverter a cegueira corneana.(AU)

Limitations and advances in new treatments and future perspectives of corneal blindness.

This review is intended to describe the therapeutic approaches for corneal blindness, detailing the steps and elements involved in corneal wound healing. It also presents the limitations of the actual surgical and pharmacological strategies used to restore and maintain corneal transparency in terms of long-term survival and geographic coverage. In addition, we critically review the perspectives of anabolic agents, including vitamin A, hormones, growth factors, and novel promitotic and anti-inflammatory modulators, to assist corneal wound healing. We discuss the studies involving nanotechnology, gene therapy, and tissue reengineering as potential future strategies to work solely or in combination with corneal surgery to prevent or revert corneal blindness.

Corneal blindness in Plato's cave: the acting forces to prevent and revert corneal opacity. Part I: epidemiology and new physiopathological concepts.

The burden of corneal blindness and visual deficiency can be felt worldwide. Its association with several endemic diseases such as childhood blindness, trauma, infectious keratitis (including variants caused by herpes, hanseniasis, and fungi), vitamin A deficiency, diabetes mellitus, and other dry eye syndromes reflects its poorly understood underlying mechanisms and suggests that the actual frequency of the disease is underestimated. The low effectiveness of preventive and therapeutic strategies against corneal scarring or deformity predicts a high frequency of patients with corneal blindness in the future. Corneal blindness is associated with environmental factors and socioeconomic limitations that restrain health assistance and maintain a modest efficiency of the current therapeutic strategies for resolving corneal diseases in large-scale programs. We present here a critical review of the concepts associated with corneal blindness that need to be considered when planning strategies to prevent and treat corneal blindness worldwide (to be able to leave Plato's cave, where corneal blindness is encaged.

Neurological and Inflammatory Manifestations in Sjögren's Syndrome: The Role of the Kynurenine Metabolic Pathway.

For decades, neurological, psychological, and cognitive alterations, as well as other glandular manifestations (EGM), have been described and are being considered to be part of Sjögren's syndrome (SS). Dry eye and dry mouth are major findings in SS. The lacrimal glands (LG), ocular surface (OS), and salivary glands (SG) are linked to the central nervous system (CNS) at the brainstem and hippocampus. Once compromised, these CNS sites may be responsible for autonomic and functional disturbances that are related to major and EGM in SS. Recent studies have confirmed that the kynurenine metabolic pathway (KP) can be stimulated by interferon-γ (IFN-γ) and other cytokines, activating indoleamine 2,3-dioxygenase (IDO) in SS. This pathway interferes with serotonergic and glutamatergic neurotransmission, mostly in the hippocampus and other structures of the CNS. Therefore, it is plausible that KP induces neurological manifestations and contributes to the discrepancy between symptoms and signs, including manifestations of hyperalgesia and depression in SS patients with weaker signs of sicca, for example. Observations from clinical studies in acquired immune deficiency syndrome (AIDS), graft-versus-host disease, and lupus, as well as from experimental studies, support this hypothesis. However, the obtained results for SS are controversial, as discussed in this study. Therapeutic strategies have been reexamined and new options designed and tested to regulate the KP. In the future, the confirmation and application of this concept may help to elucidate the mosaic of SS manifestations.

Review: MicroRNAS in ocular surface and dry eye diseases.

Since the first description of microRNAs (miRNAs) in the 1990s, more than 60 papers have described the role of miRNAs on the ocular surface and lacrimal gland (LG). MicroRNAs (miRNAs) have a role in several physiological events and in mediation of disease. They inhibit gene expression by blocking messenger RNA. Diseases such as Sjögren syndrome (SS), ocular surface neoplasias, and infections are known to increase or reduce the expression of specific miRNAs. These miRNAs play key roles in modulating inflammation, delaying or enhancing wound healing, cell differentiation metabolism, and survival. This review describes the current understanding of miRNAs as biomarkers, mediators of diseases, and potential therapeutic targets in ocular surface diseases.