OPN1MW2 is a medium-wave sensitive opsin functioning as a G protein-coupled photoreceptor in cone cells. Based on limited published evidence, it mediates visual perception through light absorption and phototransduction signaling in photoreceptor outer segments. Expression of opn1mw2 is developmentally regulated by thyroid hormone signaling 1 and responds to circadian and light-induced stimuli 2. The gene plays roles in visual function and circadian rhythm regulation, with alterations associated with visual system development and sleep-related responses.