<P> 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 , 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 . </P>
<P> 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 , 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 . </P>
how many rods are in the human eye
how many rods are in the human eye
about 120 million
about 120 million