The spatial resolution capacity of human foveal retina.

An image on the retina of a human eye enters the visual system through an array of photoreceptors that sets the boundaries on the spatial detail available for neural representation. In order to investigate the extent to which the input spatial detail is preserved by the human neural system, we compare the anatomical spatial limits as determined by the Nyquist frequency, the highest spatial frequency reconstructable from the cone array, and measures of human acuity, the minimum angle resolvable. We find that the anatomical Nyquist limits determined along the temporal horizontal meridian of a well-studied human retina (Curcio, Sloan, Packer, Hendrickson & Kalina, 1987b) offer a reasonable prediction of human acuity within the retinal region extending from slightly off the exact foveal center to about 2.0 deg of retinal eccentricity. However, we find a narrow peak of anatomical resolution at the foveal center where the acuity appears to be overestimated by cone spacing.