Foveal and peripheral thresholds for detection and resolution of vanishing optotype tumbling E’s

Abstract

We measured detection and resolution acuity for vanishing optotype tumbling E stimuli in both the fovea and at 30° in the periphery to determine if peripheral resolution is sampling limited for this stimulus. In the fovea, where acuity is optically limited, detection and resolution were the same. At 30°, 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 resolution did not change with contrast. The vanishing optotype is a legitimate perimetric stimulus to measure retinal ganglion cell density provided the task is resolution and not detection.