The potential of RdCVF administration for promoting survival of the central vision attributable to cones in patients suffering from RP is well illustrated by the finding that injection of RdCVF protein in the P23H transgenic rat model of dominant RP both slows down secondary cone loss and, more importantly, preserves cone function as measured by electroretinography [11]. The gene discussed is NXNL1; the disease is retinitis pigmentosa 1.