Visual Field Testing
A visual field acuity test is a painless test that determines how well a person can see. The test maps central vision as well as peripheral (side) vision. The test is performed by an ophthalmologist and is used to detect areas of vision loss. It can also be used to monitor the progression of previously known visual field loss.
How does a visual field test work?
During a visual field test, also called a perimetry test, you will respond to a series of flashing lights while looking straight ahead. Your responses will help the doctor determine whether you have a visual field loss. The area of vision loss gives clues as to where in the visual pathway a problem has occurred.
What does a visual field test show?
The visual field test produces a computer printout of the light thresholds that the patient's eyes were able to perceive and process. The darkest areas of the test indicate a complete loss of vision in that area. The lighter the area, the more vision the patient has in that part of the eye.
Who performs the test?
An ophthalmologist, a doctor who specializes in diseases and surgery of the eye performs the visual field test.
How should I prepare for the test?
There is no special preparation for the test. Listen closely while undergoing the test so that the results are as accurate as possible.
What happens during the test?
During the test you will sit in front of a concave dome and stare at an object in the middle. Each eye is tested separately, and the eye not being tested is covered with a patch. You will be asked to press a button when you see small flashes of light in your peripheral vision. Following the visual field test, your eyes may be dilated to examine the retina, macula, and optic nerve. This is to ensure that there is no other cause for visual field loss, visual impairment, or other ocular disease.