Visual field test (perimetry)
Your visual field is the full extent of what you can see to the sides without moving your eyes. The visual field test determines whether you have difficulty seeing in any areas of your overall field of vision. There are different types of visual field tests:
- Confrontation visual field exam. Your eye doctor sits directly in front of you and asks you to cover one eye. You look directly at your eye doctor while he or she moves his or her hand in and out of your visual field. You tell your doctor when you can see his or her hand or fingers and how many fingers you see.
- Tangent screen exam. You sit a short distance from a screen and focus on a target at its center. You tell your doctor when you can see an object move into your peripheral vision and when it disappears.
- Automated perimetry. Your eye doctor or a technician uses a computer program that flashes small lights as you look into a special instrument. You press a button when you see the lights.
Using your responses to one or more of these tests, your eye doctor determines the fullness of your field of vision. If you aren't able to see in certain areas, noting the pattern of your visual field loss may help your eye doctor diagnose your eye condition.