Figure 2.

ON-OFF visual field perimetry. a, Visual stimuli were presented in 90 different positions illustrated as circular sectors ranging from 5° to 30° in the radial axis. The visual field was divided into four quadrants by splitting the azimuth axis (nasal or temporal) and elevation axis (upper or lower visual field). Each quadrant was then divided into a number of sectors equal to the number of stimulus positions tested. The sector lines mark the half-distance in angle and radius coordinates between two stimulus positions, except for lines adjacent to a quadrant limit, which mark half the distance between the limit and the target position. b, Analysis of ON-OFF perimetry in an example subject. The visual field was mapped with dark targets (top, blue frames) or light targets (bottom, red frames) of 8 different contrasts (labels at the top). The grayscale illustrates the percentage of detection errors (white, 0%; black, 100%). The average error percentage for each stimulus contrast is shown at the bottom of the figure separately for dark (blue) and light (red) stimuli.