Visual field

A visual field test is a method of measuring an individual's entire scope of vision, that is their central and peripheral (side) vision. Visual field testing maps the visual fields of each eye individually and can detect blind spots (scotomas) as well as more subtle areas of dim vision. The visual field test is a subjective examination, so the patient must be able to understand the testing instructions, fully cooperate, and complete the entire test in order to provide useful information.

Visual field testing is most frequently used to detect signs of glaucoma damage to the optic nerve. In addition, visual field tests are useful for detection of central or peripheral retinal diseases of the retina, eyelid conditions such as drooping (ptosis), optic nerve damage and disease, and conditions affecting the visual pathways from the optic nerve to the area of the brain (occipital cortex) where this information is processed into vision.

There are a variety of methods to measure the visual fields. Visual field testing is performed one eye at a time, with the opposite eye completely covered to avoid errors. In all testing, the patient must look straight ahead at all times in order accurately map the peripheral visual field. Static automated perimetry (such as Octopus or the Humphrey Field Analyzer): Pinpoint flashes of light of varying size and brightness are projected within a large white bowl. The patient is asked to look at the center of the bowl and press a button each time a light is seen in the peripheral vision. The machine collects the data and uses sophisticated software to analyze the results.