Evaluates your visual field. This tests your vision all around your field of Central viewing (30 degrees) to see if any areas are missing. It usually involves staring straight ahead at a light and trying to see lights that appear around the sides of your view. This is generally done with a computerized system known as an automated Perimeter. This machine helps us to monitor the field of vision over time and compare it scientifically to our previous report on the same machine at the same place.