G protein-coupled photoreceptor that selectively activates G(i) protein in response to light in the retina (By similarity). Activation occurs when the opsin-bound cis-retinal chromophore absorbs a photon and isomerizes to all-trans-retinal, inducing a conformational change in the opsin that triggers a G protein-mediated phototransduction cascade (PubMed:22043319). Acts as a bistable protein with absorption peaks at 380 nm (UVA light) and 470 nm (blue light), allowing photoreversible regeneration of the cis-retinal chromophore after stimulation (PubMed:22043319). Required for the light-response in the inner plexiform layer, and contributes to the regulation of the light-response in the nerve fiber layer, via phosphorylated DAT/SLC6A3 dopamine uptake. Involved in local corneal and retinal circadian rhythm photoentrainment via modulation of the UVA light-induced phase-shift of the retina clock. Acts as a circadian photoreceptor in the outer ear and vibrissal pads, via modulation of circadian clock-gene expression in response to violet light during the light-to-dark transition phase and night phase of the circadian cycle. Required in the retina to negatively regulate hyaloid vessel regression during postnatal development via light-dependent OPN5-SLC32A1-DRD2-VEGFR2 signaling. Involved in the light-dependent regulation of retina and vitreous compartment dopamine levels. Mediates violet light-accelerated wound healing in corneas, being transiently expressed following physical injury (By similarity). {ECO:0000250|UniProtKB:Q6VZZ7, ECO:0000269|PubMed:22043319}. This is the function of OPN5 (opsin 5, Ensembl gene identifier ENSG00000124818).