Acuity perimetry and the sampling theory of visual resolution.

Visual resolution is limited by neural sampling of the retinal image everywhere in the visual field except the fovea, where optical limitations usually dominate. Consequently, measurements of resolution acuity may be interpreted as estimates of the spatial density of the mosaic of photoreceptors (in parafoveal retina) or ganglion cells (in peripheral retina) of the living human eye. Recent experiments in the basic visual sciences have paved the way for clinical applications of this approach to the problem of detecting the loss of photoreceptors and ganglion cells during aging and in a variety of retinal diseases.