A more thorough mapping of the topography of visual resolution was recently performed by Mike Wilkinson in my lab.
The aim of his study was to compare the topography of visual resolution measure psychophysically with the definitive anatomical data of Curcio and Allen. Their density map for the average human eye is shown at the left and for quantitative comparison IÕve highlighted in red the contour for 1000 retinal ganglion cells per square millimeter. Assuming a retinal magnification factor of 282 microns per degree, this anatomical map has been scaled to match the iso-acuity map at the right. Using the usual formula for nominal Nyquist frequency, the red contour on the anatomical map predicts a resolution of 4.5 cyc/deg, or 0.65 log cyc/deg. The closest contour in the psychophysical map is for 0.6 log cyc/deg, and so I colored it red also for comparison.
The striking similarity between these two contour maps provides strong support for the hypothesis that undersampling by retinal ganglion cells is the fundamental limit to spatial resolution in peripheral vision. All of the major features of the anatomical map described by Curcio & Allen are present also in the psychophysical map. The iso-density contours are elongated along the horizontal meridian, the contours are displaced into nasal retina (i.e. temporal field) which increses with eccentricity, and the contours are displaced superiorly on the retina, or inferiorly in the visual field. The visual streak is clearly evident along the horizontal meridian, and the nasal/temporal asymmetry expected for retinal ganglion cell density is also apparent psychophysically.
WWWaveTM 1996
World Wide Web automated virtual environment TM 1996
Kevin Haggerty, Indiana University.
This slide show was automatically converted to web pages by the WWWave.