The ability of the Peritest to screen for glaucomatous defects of the visual field was studied by using this automatic perimeter to examine the visual fields of 69 eyes with chronic open-angle glaucoma and 46 normal eyes after manual perimetry had been performed. The Peritest correctly identified 62 (90%) of the glaucomatous eyes as having visual field abnormalities; the other 7 eyes (10%) had false-positive results. Of the 46 normal eyes, 36 (78%) were correctly identified as having normal visual fields; the other 10 eyes (22%) were incorrectly identified as having visual field abnormalities. Thus, the overall rate with which eyes were correctly classified as having normal or abnormal visual fields was 85%, and the rate with which fields were falsely identified as having glaucomatous abnormalities was 15%.