The principal photoreceptors for image forming vision in the retina are rod and cone cells.Loss of photoreceptor cells, as happens in a number of human diseases, such as retinitis pigmentosa and age-related macular degeneration, leads to irreversible blindness.Unfortunately, the current therapeutic treatment for retinal degeneration is very limited.Here, we asked whether it is possible to restore any vision by ectopic expression of melanopsin, a newly discovered light-sensitive photopigment, in the surviving ganglion cells.The protein melanopin is normally expressed in 2%-3% of ganglion cell population of the mouse retina.To test this intriguing possibility, we used a viral vector to express mammalian melanopsin in other retinal ganglion cells of rd/rd mice, which suffer an early degeneration of rod photoreceptors and a subsequent degeneration of cones.