Photoreceptor that binds cis-retinaldehydes (By similarity). Contributes to pupillar reflex, photoentrainment and other non-image forming responses to light (By similarity). May be involved in the optokinetic visual tracking response (By similarity). May be involved in the regulation of retinal hyaloid vessel growth and regression (By similarity). Eye. Expression is restricted within the ganglion cell layer. Belongs to the G-protein coupled receptor 1 family. Opsin subfamily.