Participates in processes of transmission and amplification of the visual signal. cGMP-PDEs are the effector molecules in G-protein-mediated phototransduction in vertebrate rods and cones (By similarity). 3',5'-cyclic GMP + H2O = GMP + H(+) Oligomer composed of two catalytic chains (alpha and beta), an inhibitory chain (gamma) and the delta chain. Belongs to the rod/cone cGMP-PDE gamma subunit family.