For example, knockdown of the cone-specific opsin kinase GRK7 has a strong effect on photoresponse recovery and ectopic expression of GRK7 in zebrafish rods lowered the photosensitivity of rods [10], [11]; mutations in key proteins of the phototransduction cascade lead to blindness and cone degeneration [12]. This evidence concerns the gene GRK7 and Blindness.