and scotopic function compared to pbs treatment fig2 j l there was no effect of nmn on littermate control animals in these experiments nampt cone cko mice without nmn treatment demonstrated similar but milder changes on biomicroscopy consistent with neuroretinal degeneration as seen in the rod cko mice fig3 a erg demonstrated significant and progressive decline in cone function as evidenced by reduced photopic responses over time with secondary reduction in scotopic responses fig3 b d these quantifiable structural and functional changes were associated with decrease in visual acuity in cone cko mice fig3 e histopathologic analyses confirmed outer nuclear layer degeneration with subsequent multilayer retinal degeneration and cell death in cone cko mice similar to the changes seen above for rod cko mice as with nampt rod cko mice delivery of nmn i p to nampt cone cko mice was also able to improve erg function compared to pbs treated cone cko mice fig3 f h nmn treatment had no effect on littermate controls fig3 a b these data suggest that without being limited by theory nampt mediated nad biosynthesis is necessary for the survival and function of both rod and cone pr neurons furthermore providing nmn treatment is able to rescue pr neurons and vision the inventors used a 661w cone pr cell.