A visual field test measures how much 'side' vision you have. It is a straightforward, painless test, and does not involve eye drops. Lights or images are flashed on a screen, and you will press a button to indicate you have seen the stimulus. You will put your chin in a chin rest and your forehead will maintain contact with the forehead rest bar. Each eye will be tested individually while you sit as still as you are able. You will be asked not to move your eyes, however will be allowed to blink whenever you feel the need. Don't worry if you feel that you missed some of the stimuli as some of the flashes are purely to check if you are concentrating, and others are a repeat to insure completeness.
Most often the test is used as a screening on people who have no perfectly normal health. The results of the test can be used by the doctor to diagnose and follow the progression of glaucoma, or to detect neurological problems.