Perimetry Test (Visual Field Testing) for Glaucoma. Guide. A perimetry test (visual field test) measures all areas of your eyesight, including your side, or peripheral, vision. To do the test, you sit and look inside a bowl-shaped instrument called a perimeter. While you stare at the center of the bowl, lights flash.You press a button each time you see a flash.uide. A perimetry test (visual field test) measures all areas of your eyesight, including your side, or peripheral, vision. To do the test, you sit and look inside a bowl-shaped instrument called a perimeter. While you stare at the center of the bowl, lights flash. You press a button each time you see a flash.