How many ganglion cells are there to a foveal cone? A stereologic analysis of the quantitative relationship between cone and ganglion cells in one normal human fovea.

Published studies on humans and monkeys show discrepancies in the reported quantitative relationship between cones (C) and ganglion cells (G). Data on human foveal retina suggest that it cannot accommodate the midget on-off system in addition to other functional channels. Foveal cell densities along the vertical meridian (0-1.8 mm eccentricity) were estimated in one normal human retina using the disector method. Cell ratios were calculated from cumulative total numbers. G density peaked at 0.65 mm eccentricity and C density at the foveola. Cumulative cell numbers showed a more rapid increase in G than in C with increasing eccentricity. G/C ratios of 2.7-3.4 were found using lateral displacement data modified from macaque. Using one estimate of displacement from the sections, the G/C ratio was 3.0. This study shows that there are on average three ganglion cells per foveal cone in humans, as in monkeys.