PDE6B and retinal degeneration: This has led to the development of a wide-spread notion that the speed of retinal degeneration in this model is too fast to allow a window of opportunity for treatment14, 15, 16, 17, 18, 19 This hypothesis has been bolstered by an effective gene supplementation therapy in the canine model of PDE6B deficiency (rcd1 dog)20 and in the hypomorphic Pde6b-mutant (rd10) mouse15, 18, 19.