Obtaining a parts list of the sensory components of the retina is vital to understanding the effects of light in behavior, health, and disease. Rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) are the best described photoreceptors in the mammalian retina, but recent functional roles have been proposed for retinal neuropsin (Opn5) - an atypical opsin. However, little is known about the pattern of Opn5 expression in the retina.