White noise field campimetry. A new form of perimetric examination

Abstract

Patients with circumscribed visual field defects can perceive them while looking at a surface with small black and white spots flickering randomly at high frequency (such as the white-noise field of a TV screen following the end of transmissions for the day). This autonomous perception of scotomata can be used as a screening method, to perform subsequent manual or automatic grid perimetry with the same TV monitor, concentrating on the defective part of the visual field alone. The results of white-noise scotometry used to examine the visual fields of 161 patients are presented. It appears that the test is capable of identifying suprageniculate homonymous hemianopias, since patients either do not observe them at all in the white-noise field or only to a far lesser degree. In addition, the blind spot and some congenital visual field defects are not observed as visual field defects at all in the white-noise field. However, all acquired circumscribed defects caused by lesions of the first, second, or third neuron are readily seen in the white-noise field if the patient is capable of stable fixation.