Biological extracellular vesicles in tear fluids, such as exosomes, are thought to have physiological functions in the management of healthy ocular surface epithelium, including corneal epithelium. However, the physiological roles of tear extracellular vesicles in the ocular surface remain unclear. In this study, we investigated the physiological function of tear extracellular vesicles in mouse tear fluids in the ocular surface epithelium in vitro. Morphological analysis of the isolated extracellular vesicles from mouse tear fluids was performed using nanoparticle tracking analysis and transmission electron microscopy. The identified particles were characterised by immunoblotting for exosomal markers. After confirming the uptake of tear exosomes in cultured corneal epithelial cells, gene expression changes in mouse cultured corneal epithelial cells after tear exosome treatment were analysed. Immunostaining analysis was performed to confirm cell proliferation in the cultured corneal epithelial cells with tear exosome treatment. Tear fluids from mice contain nanoparticles with exosome-like morphologies, which express the representative exosomal markers CD9 and TSG101. The extracellular vesicles can be taken up by cultivated murine corneal epithelial cells in vitro and induce expression changes in genes related to the cell cycle, cell membranes, microtubules, and signal peptides. Treatment with the tear extracellular vesicles promoted cell proliferation of cultured murine corneal epithelial cells. Our study provides evidence that murine tear fluids contain extracellular vehicles like exosomes and they may contribute to the maintenance of the physiological homeostatic environment of the ocular surface.

Extracellular vesicles (EVs) are increasingly recognized as mediators of intercellular communication and as potential therapeutic and diagnostic platforms. In the ocular surface and anterior segment, EVs are released by epithelial, stromal, endothelial, immune, and aqueous outflow-related cells and are also detectable in tears and aqueous humor. Experimental studies suggest that EVs may promote corneal epithelial repair, modulate local immune responses, reduce stromal fibrosis, and participate in extracellular matrix regulation within the trabecular meshwork. In parallel, mesenchymal stromal cell-derived EVs are being investigated as cell-free therapeutics, while engineered EVs and EV–lipid hybrid systems may facilitate the delivery of nucleic acids and other therapeutic cargo to anterior segment tissues. Tear- and aqueous humor-derived EV preparations have also yielded candidate molecular signatures for ocular surface disease, glaucoma, and selected systemic disorders. However, much of the current evidence remains preclinical or exploratory. Reported effects are frequently based on conditioned medium, EV-enriched fractions, or incompletely characterized preparations, making it difficult to distinguish EV-specific activity from that of the broader secretome. Biomarker studies are additionally limited by small cohorts, low sample volumes, non-vesicular contaminants, and methodological heterogeneity. This review summarizes the biological roles, therapeutic applications, drug-delivery potential, and diagnostic use of EVs in anterior segment medicine. Particular emphasis is placed on the strength of EV-specific evidence, the limitations of extrapolating from non-ocular models, and the methodological, manufacturing, and regulatory requirements for clinical translation. EVs represent a promising interface between anterior segment biology, precision diagnosis, and targeted therapy, but rigorous characterization and comparative validation remain essential.