what are the cones in the retina sensitive to
Cone cell Cone cells, or cones, are one of three types of photoreceptor cells in the retina of mammalian eyes (e.g. the human eye). They are responsible for color vision and function best in relatively bright light, as opposed to rod cells, which work better in dim light. Cone cells are densely packed in the fovea centralis, a 0.3Â mm diameter rod-free area with very thin, densely packed cones which quickly reduce in number towards the periphery of the retina. There are about six to seven million cones in a human eye and are most concentrated towards the macula.[1] The commonly cited figure of six million cone cells in the human eye was found by Osterberg in 1935.[2] Oyster's textbook (1999)[3] cites work by Curcio et al. (1990) indicating an average close to 4.5 million cone cells and 90 million rod cells in the human retina.[4]
Photoreceptor cell The human retina contains about 120 million rod cells, and 6 million cone cells. The number and ratio of rods to cones varies among species, dependent on whether an animal is primarily diurnal or nocturnal. Certain owls, such as the tawny owl,[6] have a tremendous number of rods in their retinae. In addition, there are about 2.4 million to 3 million ganglion cells in the human visual system, 1 to 2% of them photosensitive. The axons of ganglion cells form the two optic nerves.