Appearance of the frequency doubling stimulus in normal subjects and patients with glaucoma

Abstract

PURPOSE. To determine whether the spatial structure of the frequency doubling technology (FDT) perimetry stimulus is visible at detection-contrast threshold in normal observers and those with glaucoma and to assess its perceived spatial frequency at threshold and suprathreshold contrast. METHODS. Three subject groups were assessed: 10 young normal observers (aged 50 years), and 10 subjects with glaucoma. Detection thresholds for centrally and eccentrically presented 10° squares, 0.25-cyc/deg, 25-Hz counterphase flicker sine-wave gratings were obtained by using a yes-no staircase procedure. Eccentric locations were in areas of loss of FDT sensitivity (≤21°) in subjects with glaucoma, or at 7°..