Cortical acuity and the luminous flux collected by retinal ganglion cells at various eccentricities in human rod and cone vision.

Using areally M-scaled, luminance-modulated orange-red and black-and-white gratings, we measured monocular resolution as a function of luminance at various eccentricities in the temporal visual field. In cone vision the increase of grating acuity with luminance became similar at all eccentricities when (1) acuity values were divided by the human cortical magnification factor to express grating resolution in cortical terms (c mm-1) and (2) retinal illuminance was multiplied by Ricco's area to express luminance in terms of photopic luminous flux. The same MF-scaling procedure also applied to scotopic acuity except that the amount of luminous flux collected by retinal ganglion-cell receptive-fields was in rod vision found to increase with eccentricity faster than photopic Ricco's area.