Melanopsin cells are the principal conduits for rod–cone input to non-image-forming vision

Mice lacking intrinsically photosensitive retinal ganglion cells (ipRGCs) retain pattern vision but show significant deficits in both pupillary light reflex (PLR) and circadian photoentrainment.

• Animals without ipRGCs demonstrate impairments in PLR and circadian photoentrainment that exceed those seen in melanopsin knockout mice.
• Deficits in these non-image-forming functions resemble those in animals lacking phototransduction across all three photoreceptor types.
• Retinal ganglion cells dissociate light signals for detecting light intensity from those used for pattern vision.
• Despite the inability to detect light for non-image-forming functions, these animals can still form images.

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