The projection perimeter is used to check the sensitivity of the human eye to light(visual acuity). Ambient light by refraction system to the retina, the retinal photochemical reactions by bioelectrical, transmitted through the visual pathway visual cortex, the brain through a comprehensive analysis of the formation of vision. Any part of the distribution from the retina to the visual cortex nerve fibers, direction, known as the road lesions occur, it will be reflected in the vision, visual field changes according to the results of other tests and clinical, can analyze the site of the lesion, nature and prognosis
A mains electricity (AC-powered), automatically operated, diagnostic, ophthalmic instrument intended for assessing the extent of the patient's peripheral visual field. Small luminous points (spots) are automatically displayed in various random positions and patient response is automatically recorded. The print-out (chart) then shows the resulting curve of the visual field. Such types include Humphrey perimeters.