PDE6B and retinitis pigmentosa 1: With respect to disease progression, our nonlinear mixed models revealed that the IS/OS band width decreased linearly at a rate of − 112.4 μm (6.5%) per year; a similar rate was reported in a previous study of RP associated with variants of genes in the PDE6 gene family, including PDE6A and PDE6B (− 91 μm [5.9%]/year)27.