OPN5 (neuropsin) is a G-protein coupled receptor functioning as a violet/ultraviolet light-sensitive non-visual photopigment expressed in retinal and extraocular tissues 1. In the retina, OPN5 mediates light-dependent phototransduction via selective activation of Gi proteins, reducing cAMP levels 2, and regulates circadian photoentrainment and dopamine-dependent light responses 3. OPN5-expressing retinal ganglion cells suppress lens-induced myopia through violet light detection in a time-dependent manner, identifying a key mechanism for myopia prevention 4. Beyond vision, OPN5 exhibits critical extraocular functions: corneal epithelial cells express OPN5 upon wounding, and violet light exposure accelerates epithelial wound healing through OPN5-dependent calcium signaling and MAPK phosphorylation 56. OPN5 also mediates extraocular photoentrainment of circadian rhythms in skin and regulates light-dependent hormone release 1. Species-specific signaling diversity exists, with human OPN5 preferentially activating Gq-mediated calcium signaling rather than Gi pathways 1. Clinically, insufficient OPN5 activation due to reduced violet light exposure may contribute to myopia progression and impaired wound healing, suggesting therapeutic potential in modern indoor-dependent lifestyles.