The visual field test measures a person's vision in each direction (the peripheral vision). Some visual field tests also evaluate the function of the central vision.
A screening visual field test may be done as part of a routine eye exam. More commonly, it is a separate exam and may be used to diagnose serious diseases of the eyes or brain. For example, visual field testing is commonly done to help diagnose and monitor glaucoma.
There are a number of variations of this test. It can be performed by a healthcare provider or by a machine. When a provider does the test, he or she asks the person to look straight ahead. The provider then places his or her hand or an object somewhere in the field of vision. While the person looks straight ahead, he or she is asked if the hand or object is visible. This is a simple screening test, often done as part of a routine exam.
In the machine test, the person sits in front of a machine with one eye covered. The person is asked to focus the open eye on a central spot. Lights appear in various areas in the field of vision. The person is asked to respond if he or she sees the spots. Often, a person is asked to press a button when a spot appears. The person's responses create a map of the visual field. Other versions of the test use different colors for spots and backgrounds or other shapes.
No special preparation is generally needed for this test.
Results of the test are normal if the field of vision is as expected for the person's age. If there are defects in the field of vision, certain disease may be present. These can include: glaucomadamage or inflammation of the nerves of the eyedamage to the retina from congenital retinal disease or the toxic effects of some medicines.damage to the brain, such as a strokeother eye diseases