Color blindness as part of the retinal damage caused by diabetes. Vitamin A deficiency may also cause color blindness. Some subtle forms of color blindness may be associated with chronic solvent-induced encephalopathy (CSE), caused by long-time exposure to solvent vapors. Red–green color blindness can be caused by ethambutol, a drug used in the treatment of tuberculosis. The typical human retina contains two kinds of light cells: the rod cells (active in low light) and the cone cells (active in normal daylight). Normally, there are three kinds of cone cells, each containing a different pigment, which are activated when the pigments absorb light.
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