Human albinos can discriminate spatial frequency and phase as accurately as normal subjects

Abstract

Previous experiments testing grating and vernier acuities in albino central vision are consistent with the hypothesis that the deficit in their monocular spatial processing is mainly due to the increased spacing of their foveal cones. This was tested by measuring albino spatial frequency discrimination over the range 0.25–4.0 cpd. The same experiments were performed on three normal subjects both in the fovea and at a peripheral locus at which their grating acuity was identical to that of the albino subjects. Spatial frequency discrimination thresholds averaged 3.71% for albinos, 5.18% for the normal fovea, and 8.81% for the normal periphery, the latter being over 2.3 times greater than albino thresholds. A comparable pattern of results was observed in phase discrimination experiments. These data reject the possibility that albino central vision is similar to normal peripheral vision, but the results are predictable on the hypothesis that the central retina of albinos is a spatially magnified (underdeveloped) version of the normal fovea.