Despite these studies, however, Pawlyk et al. [36] and Takano et al. [41] found no rescue effects of D-cis-diltiazem on retinal degeneration in rd1 mice, and Bush et al. [42] also reported that D-cis-diltiazem was ineffective for photoreceptor rescue in rhodopsin P23H transgenic rats. Here, PDE6B is linked to retinal degeneration.