Humphrey® Field Analyzer (HFA™ II-i )
The Gold Standard in Perimetry
If Dr. Fite orders a visual field examination for you, this test will draw a map of how well you see in the center and sides of your vision. The exam will be done by a computerized machine called the Humphrey Field Analyzer. This machine is one of the best methods to measure the visual field. The exam is not hard. This handout will tell you what to expect when you have this exam.
Since this exam draws a map of your vision, it is important that you hold your eye still and look straight ahead at all times. Inside the machine there is a steady white light for you to look at. Unless told otherwise, you should stare at this light at all times. The test lights will flash on and off at different times and different places within the machine. You will be given a response button to hold. You should press the button whenever you think you have seen a light flash. The best time to blink is right after you have pushed the button. Some lights will be bright and some will be dim. Some of the lights will be too dim to be seen. There will be periods of time when you will not see anything. Don’t be alarmed by this. The machine purposely makes some of the lights too dim. This will measure how sensitive your eye is at different areas.
During the exam, you will hear a range of noises as the light projector moves and the shutter opens and closes. Try to ignore these noises and respond only to the lights. At times, the machine tests your responses by either not projecting any lights (to see if you are responding to the noises) or projecting very bright lights (to see if you are paying attention).
This exam can take up to 20 minutes for each eye. It is very important that you be seated comfortably with your forehead pushed forward into the machine as far as possible. You should feel relaxed with no pressure in your shoulders or neck. The light should be clearly in focus. You should let the technician know right away if you are not comfortable or if the light is not in focus. If you wish to rest during the exam, hold down the response button. The machine will beep and alert the technician to pause the test.
It is hoped that this information will make visual field testing easier for you. Talk with Dr. Fite or your technician if you have questions.