Photoreceptor death is the endpoint of many blinding diseases. Rod or cone photoreceptor-specific deletion of nicotinamide phosphoribosyltransferase (Nampt), the rate-limiting enzyme in the major NAD+ biosynthetic pathway beginning with nicotinamide, causes retinal degeneration. In both cases, we could rescue vision with nicotinamide mononucleotide (NMN)[8].