Corneal pain is considered to be a core symptom of ocular surface disruption and inflammation. The management of this debilitating condition is still a therapeutic challenge. Recent evidence supports a role of the opioid system in the management of corneal nociception. However, the functional involvement of the mu opioid receptor (MOR) underlying this analgesic effect is not known. We first investigated the expression of the MOR in corneal nerve fibers and trigeminal ganglion (TG) neurons in control mice and a mouse model of corneal inflammatory pain. We then evaluated the anti-nociceptive and electrophysiological effects of DAMGO ([D-Ala,N-Me-Phe,Gly-ol] enkephalin), a MOR-selective ligand. MOR immunoreactivity was detected in corneal nerve fibers and primary afferent neurons of the ophthalmic branch of the TG of naive mice. MOR expression was significantly higher in both structures under conditions of inflammatory corneal pain. Topical ocular administration of DAMGO strongly reduced both the mechanical (von Frey) and chemical (capsaicin) corneal hypersensitivity associated with inflammatory ocular pain. Repeated instillations of DAMGO also markedly reversed the elevated spontaneous activity of the ciliary nerve and responsiveness of corneal polymodal nociceptors that were observed in mice with corneal pain. Finally, these DAMGO-induced behavioral and electrophysiological responses were totally blunted by the topical application of naloxone methiodide, an opioid receptor antagonist. Overall, these results provide evidence that topical pharmacological MOR activation may constitute a therapeutic target for the treatment of corneal pain and improve corneal nerve function to alleviate chronic pain.
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http://dx.doi.org/10.1016/j.biopha.2020.110794 | DOI Listing |
Optom Vis Sci
January 2025
School of Optometry and Vision Science, UNSW Sydney, Sydney, New South Wales, Australia.
Significance: In an aging population, the number of people living with neurodegenerative disease is projected to increase. It is vital to develop reliable, noninvasive biomarkers to detect disease onset and monitor progression, and there is a growing body of research into the ocular surface as a potential source of such biomarkers.
Background: This article reviews the potential of in vivo corneal confocal microscopy and tear fluid analysis as tools for biomarker development.
J Cyst Fibros
January 2025
Pulmonology Department, Regional University Hospital of Malaga, Department of Medicine and Dermatology, University of Malaga, Biomedical Research Institute of Malaga (IBIMA) - Bionand Platform, Malaga, Spain. Electronic address:
Background: Cystic fibrosis (CF) is caused by variants in a gene that encodes a protein essential for water and ion transport in the epithelial cells of exocrine organs. Given the possible relationship of this protein and conjunctival and corneal epithelium, the aim of this study was to evaluate ophthalmologic alterations in people with CF.
Methods: Forty-five people with CF underwent pulmonary evaluation including inflammatory score (IS).
Exp Eye Res
January 2025
Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA. Electronic address:
Radiotherapy is one of the conventional treatments for head and neck malignancies. Despite the implementation of protective measures to minimize the detrimental impact on healthy tissues surrounding the radiation site, radiation keratopathy remains a prevalent complication. We aimed to establish a mouse model of radiation keratopathy to characterize the pathophysiology of the disease and enable future identification of potential treatments.
View Article and Find Full Text PDFSurg Neurol Int
December 2024
Department of Surgery, Baghdad Teaching Hospital, Baghdad, Iraq.
Background: Orbital bullet injuries resulting from high-velocity trauma pose significant clinical challenges due to the potential for severe ocular and systemic complications. This meta-analysis consolidates the existing body of knowledge on direct orbital bullet injuries with respect to clinical outcomes, management strategies, and long-term effects.
Methods: The literature search was conducted by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, using databases such as PubMed and Scopus.
Regen Biomater
November 2024
Zhejiang Top-Medical Medical Dressing Co. Ltd, Wenzhou, Zhejiang 325025, China.
Decellularization is the process of obtaining acellular tissues with low immunogenic cellular components from animals or plants while maximizing the retention of the native extracellular matrix structure, mechanical integrity and bioactivity. The decellularized tissue obtained through the tissue decellularization technique retains the structure and bioactive components of its native tissue; it not only exhibits comparatively strong mechanical properties, low immunogenicity and good biocompatibility but also stimulates neovascularization at the implantation site and regulates the polarization process of recruited macrophages, thereby promoting the regeneration of damaged tissue. Consequently, many commercial products have been developed as promising therapeutic strategies for the treatment of different tissue defects and lesions, such as wounds, dura, bone and cartilage defects, nerve injuries, myocardial infarction, urethral strictures, corneal blindness and other orthopedic applications.
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