Foveal and peripheral thresholds for detection and resolution of vanishingoptotype tumbling E's

We measured detection and resolution acuity for vanishing optotype tumbling E stimuli in both the fovea and at 30 degrees in the periphery to determin e if peripheral resolution is sampling limited for this stimulus. In the fo vea, where acuity is optically limited, detection and resolution were the s ame. At 30 degrees, however, detection was markedly better than resolution indicating that peripheral resolution is sampling limited for this stimulus . Detection acuity was higher when contrast was 90% rather than 40%, but re solution did not change with contrast. The vanishing optotype is a legitima te perimetric stimulus to measure retinal ganglion cell density provided th e task is resolution and not detection. (C) 1999 Elsevier Science Ltd. All rights reserved.