Fig. 3. Density of rods and cones across the retina. Cone density is greatest at the fovea and declines rapidly with eccentricity, although cones are present across the entire retina. Rods are absent in the fovea, reach peak in a parafoveal ring, and greatly outnumber cones in the periphery. (Osterberg G: Topography of the layer of rods and cones in the human retina. Acta Ophthalmol Suppl 6:1, 1935.)