Abstract
Recently, non-cone, non-rod photoreceptor was discovered in rat retinal ganglion cells (RGCs). These photosensitive RGCs are small percentage of RGCs with morphological and functional features. The photosensitive RGCs, cones, rods are necessary for photopic input to the non-image-forming effect: locomotor activity, pupil light reflex, melatonin suppression. An action spectrum for melatonin suppression has a peak wavelength sensitivity of 460nm. However it is suggested that additivity is not approved from melatonin suppression using polychromatic light, non-image-forming effect may be a complicated mechanism.
