An optical system having a spectral transmission profile having an average transmittance Ta between 380 nm and 780 nm and an average red light transmittance Tr between a first limit L1 and a second limit L2, with Tr <； 2*Ta/3 and L1 = 600 nm and L2=780 nm, and the optical system being configured to allow by transmission or also by emission selective retinal exposure of an eye to at least one selected range of wavelengths of light in the visible spectrum of 460 nm to 530 nm.
