Meridional threshold testing was used to compare the quantitative abilities of the Octopus 201, Humphrey 620, and Tübingen perimeters. In 40 patients with mild to moderate glaucomatous visual field defects, the perimeters provided comparable results, and only small differences could be identified. Manual Tübingen testing identified slightly fewer defects, and scotomas were plotted as narrower and shallower than on the two automated devices, which were nearly equivalent in performance.