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 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 receive connections from rods and cones, allowing them to encode colour and spatial information. Dacey "et al". found the giants' receptive field sizes to be about three times the diameter of those of parasol ganglion cells. There are only about 3000 giant retinal ganglion cells in each retina, comprising about 0.2% of the total number