Visual field testing (perimetry) monitors peripheral vision. Visual fields are obtained to monitor visual changes that may be caused by specific eye diseases, such as glaucoma, as well as the neurological function of the retina, optic nerve and brain.
There are different types of visual field exams, usually they require the patient to focus on one spot and respond to flashing lights by pressing a button. In automated perimetry, you sit in front of a concave dome and stare at a central target within the dome. A computer driven program flashes small lights at different locations within the dome's surface, and you press a button when you see the small lights in your peripheral vision. Your responses are compared to age-matched controls to determine the presence of defects within the visual field.