A major problem in mass screening for glaucoma is the substantial time required to detect areas of depressed visual sensitivity, scotoma. We have developed a novel instrument for testing rapidly and automatically the sensitivity of the visual field. The patient views a large CRT screen on which up to four luminous points are presented in a prearranged pattern. The patient's vocal response is a number from zero to four, the number of stimulus points that he has observed, which is recognized by the controller and recorded. A series of 90 such patterns is presented sequentially, giving a 288 points visual field test, at the conclusion of which a hard copy probabilistic map of the retinal location of scotoma is drawn. The examination procedure is much faster than that using conventional 'automatic' tests and its results are almost identical with those from two commercial instruments with which our experimental 'perimeter' has been compared. Initial clinical trials are very encouraging.