125 to 260 μm
||Human Homo sapiens
||Perry VH, Cowey A. The ganglion cell and cone distributions in the monkey's retina: implications for central magnification factors. Vision Res. 1985 25(12):1795-810. p.1804 left column 2nd paragraphPubMed ID3832605
||Missotten L. Estimation of the ratio of cones to neurons in the fovea of the human retina. Invest Ophthalmol. 1974 Dec13(12):1045-9.PubMed ID4430574
||(Primary source abstract:) "The
ratio of pedicles over neurons has been
determined in thin sagittal and flat
sections of the rod-free central area of
the human retina."
||P.1804 left column 2nd paragraph: "For the present purposes an important point concerns the functional offset introduced by the displacement of the ganglion cells away from the fovea. The length of the fibres of Henle determines the extent of this offset. Unfortunately there are no precise measurements of their length at different eccentricities. Polyak ((1957) The Vertebrate Visual System, Univ. of Chicago Press, Chicago., p. 227) described them as “stretching for hundreds of microns”. Missotten (1974, primary source) estimated in man, but without direct evidence, that they may be as long as 125-260µm for foveal cones and up to 600µm for cones 0.5 mm from the fovea. Thus the maximal offset may be of the order of 2-3 degrees of visual angle and this should be borne in mind for the comparisons that follow."