This is important for conditions such as Glaucoma, retinal detachments, optic neuritis, retinal blood vessel blockage, brain tumors, ptosis (lid lag), auto-immune conditions like lupus, and many others.
Sitting in front of a concave 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. The test will detect any loss of peripheral vision and provide a map of that loss which will be helpful in diagnosing the cause.