Peripheral Visual Acuity

Since the classical work of Wertheim1there have been many studies of peripheral visual acuity. Those published prior to 1951 were thoroughly reviewed by Low.2Data from representative investigations are shown in Fig 1. Only two studies provide any information as to the variability of normal acuity at each eccentric location. Low's paper3on the acuity of 100 normal subjects gives data only for the far periphery, 30°, 60°, and 90° from fixation. Weymouth4published values of the mean threshold visual angle and its standard deviation for six locations between fixation and 20°. These are based on records of 20 students in a laboratory course. The mean acuities are, at all tested locations, far below any reported in other studies; for example at the fovea, about 20/40; at 5 degrees in the periphery, 20/200. These low acuities are perhaps to be attributed to the use of