It is interesting to notice that RP subjects have an imbalance of the antioxidant-oxidant status in the peripheral blood [41] that leads to an increase in free radicals, chronic oxidative stress, and subclinical inflammation which may stimulate cells to secrete more ET-1, as in a vicious circle; on the other hand, increased ET-1 may, in turn, lead to vascular dysregulation and hypoxic stress with resulting activation of inflammatory pathways. Here, EDN1 is linked to retinitis pigmentosa 1.