"Proper head position is critical with all visual field screening tools."
The design of the FDT head rest encourages proper positioning. Glasses frames can sometimes get in the way, blocking full view of the screen and flickering bars. A slight turn of the head usually provides a full view, though if necessary, glasses may be removed in most instances. When an individual's height makes positioning a challenge, try raising the subject's end of the FDT for taller persons or the screener's end for shorter persons. Needless referrals result when the test is failed because the subject's view is blocked! Ask the subject, "Can you see the blue border all around the screen?" Proper head position is critical with all visual field screening tools.** Prevent Blindness Northern California suggested addressing proper positioning for FDT users, and shared their success with in-office screening.
********* & *********
a) Prepare the Prototype for a Patient Test
> Start with the patient viewport ready for the right eye test position
b) Explain the procedure to the patient
"...stare at the dot in the center of the screen the entire time."
"You will look into this viewport at a video screen and stare at the dot in the center of the screen the entire time. From time to time, these different patterns (Show the patient the sample chart depicting the different patterns) of vertical black and white bars will momentarily appear flickering in different areas of the screen. The patterns will sometimes be very faint and at other times be very distinct. Momentarily press the response button whenever you see the flickering vertical black and white bars of one of the patterns. You are NOT expected to see the bar patterns at all times. Please remember to stare at the dot in the center of the screen during the entire test. If you need to rest or ask questions during the test, you can pause the test at anytime by pressing and holding down the reponse button."
"Do you have any questions? Do you understand how to take the test?"
c) Prepare the patient
> Place the response button in the patient's hand and show him/her how to press it
> Ask patient to place his/her forehead on the brow rest and lookin into the viewport
> Adjust the height of the chair or table (or both) to obtain a comfortable position
> Remind the patient to stare at the dot in the center of the screen
d) Running a Screening or Threshold Patient Test
> Right eye first; then slide viewport for Left eye after the patient finishes with the right eye
e) Obtain print out of results
** FDP Prototype Operating instructions rev 5.50 Dec 2nd, 1996. Welch Allyn Medical Products. Sight and Soul Hoffberger Program for the Prevention of Blindness
Questions or Comments? Please email WebMaster
Written: 04/28/02; Updated: 04/28/02 v.1.1