Optics and vision conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can distinguish about 10 million colors. The human eye's non-image-forming photosensitive ganglion cells in the retina receive the light signals which affect adjustment of the size of the pupil, regulation and suppression of the hormone melatonin and entrainment of the body clock. Visual acuity is acuteness or clearness of vision, especially form vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity
Giant retinal ganglion cells an S-Off, (L + M)-On opponency. Their spatial modulation transfer function is low-pass, with an upper limit of about 0.6 cycles per degree. Dacey "et al". propose that the giants subserve the subconscious, 'non-image-forming' functions of circadian photoentrainment and pupillary diameter, and via the rod and cone inputs, may help mediate conscious perception of irradiance. Giant retinal ganglion cells Giant retinal ganglion cells are photosensitive ganglion cells with large dendritic trees discovered in the human and macaque retina by Dacey "et al". (2005). Giant retinal ganglion cells contain a photo-pigment, melanopsin, allowing them to respond directly to light. They also