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Visual Field: Field Protocol
Date of SC final approval
About the Measure
Domain:
Ocular
(included in Survey &
Supplemental Information)
Measure:
Visual Field: Field Protocol
(included in Survey &
Supplemental Information)
Definition:
(included in Survey &
Supplemental Information)
Purpose:
Measurement of an individual's vision field (central and peripheral vision) will be tested
with Frequency Doubling Technology (FDT) using the Humphrey Matrix perimetry
instrument.
Visual field testing is used to detect defects in the visual pathway which extends from
the tear film that coats the cornea to the occipital cortex.
About the Protocol
Description of
Protocol:
(included in Survey & Supplemental
Information)
Selection Rationale:
Specific Instructions:
Protocol text:
(included in Survey & Supplemental
Information)
Visual field testing is performed on each eye of the participant using the FullThreshold N-30 (N-30-F) and the 24-2 Threshold procedures on the Humphrey Matrix
Frequency Doubling Technology (FDT) visual field instrument (Carl Zeiss Meditec,
Inc., Dublin, CA).
The Frequency Doubling Technology (FDT) instrument uses a frequency doubled
stimulus designed to specifically target a subset of retinal ganglion cells called M-cells
but defects in other parts of the visual pathway will also yield abnormalities on this
test. The FDT instrument is a table top instrument weighing only 19 lbs that requires
little patient set-up, no eye patch or special trial lens for testing. Its ability to screen for
glaucoma in the ophthalmology clinic setting is well documented. The FDT instrument
costs considerably less than the Humphrey Automated Field Analyzer (HVFA) ($6,500
versus $29,000 in February 2010) but the instrument itself does not store raw data
that is generated which must either be downloaded to another computer as a .PDF file
or to hard copy. The FDT instrument is a desirable, inexpensive and less technicianintensive alternative instrument for assessing the visual field that may be suitable for
some purposes, especially for glaucoma screening in a non-ophthalmic setting.
None
Subjects will have two Frequency Doubling Technology (FDT) tests using the
Humphrey Matrix, the Full-Threshold N-30 (N-30-F) and the 24-2 Threshold
procedures performed on each eye. To perform both the N-30-F and 24-2 tests, it is
essential that you have a Humphrey Matrix and not an original FDT instrument.
The tests should be administered using the Subject’s normal distance correction
(glasses or contact lenses). Eyeglasses with bifocal corrections can be used.
ENTERING SUBJECT DATA
Version 9 – 8/10/09
Visual Field: Field Protocol
Date of SC final approval
1. The MAIN MENU can be accessed by pressing the F1 button located at the upper
right corner of the Humphrey Matrix Screen.
2. From the MAIN MENU of the HUMPHREY MATRIX, select N-30-F FDT Threshold
or 24-2 FDT Threshold under the Threshold menu by pressing this location on the
screen.
3. After this selection, you will be taken to the “View Patients” screen. Select “Add
New Patient” by pressing this button at the top left portion of the screen and enter in
the subject ID and date of birth, other information. After this select “Add Patient” by
pressing the button in the lower right portion of the screen.
4. Enter the Pupil Diameter, Visual Acuity, and Rx as described in the table below.
FDT Screen:
Pupil Diameter
Information Entered:
RE: e.g., 4 mm
LE:
Visual Acuity
RE: e,g,, 20/20
LE:
Rx Used
RE: 1(+ or -) _.__ DS (+ or -) _.__DC X ___DEG
LE: (+ or -) _.__ DS (+ or -) _.__DC X ___DEG
1
Enter 3 digits for each, 0.00 for plano. “Rx Used” is the correction that is used for
performing visual field testing.
5. The Operator LCD Display will indicate if there is too much ambient light to perform
a reliable test. Lower the room lighting or change the test location until suitable test
conditions are achieved. Also, if the subject response button is not connected or the
subject visor is in the wrong eye position, this will be indicated on the operator LCD
display.
PREPARING THE SUBJECT
For the eye being tested, if the brow is heavy or the upper lid is drooping, tape it
accordingly. When in doubt, tape the upper lid. Slide the subject visor to the study eye
test position and ask the Subject to place their forehead on the forehead rest and look
into the subject eyepiece at the video screen. Adjust the height of the chair or table (or
both) to obtain a comfortable position for the Subject. Confirm that the Subject can
see the entire lit video screen, including all four corners in the subject eyepiece,
establish that they can see the black dot in the middle of the screen and that their eye
is centered on the video screen. Make sure that the Subject is properly aligned with
the instrument by asking him/her to look to each of the four corners of the display to
make sure that the display is not obscured.
Select the “Freeze” button to freeze the live image of the eye to measure the Subject’s
pupil diameter. Measure the Subject’s pupils to the nearest 0.5 mm. If they are less
than 3 mm in diameter, dilate them with 2.5% phenylephrine drops, unless
contraindicated. If this is ineffective, dilate with a cycloplegic agent and wait a full 20
minutes before beginning the test. If a Subject’s pupil is < 3 mm with cycloplegia,
he/she is ineligible for visual field testing and cannot be enrolled in the study. After
measuring the Subject’s pupil diameter, press the “Unfreeze” button to return to a live
video of the Subject’s eye.
Version 9 – 8/10/09
Visual Field: Field Protocol
Date of SC final approval
FDT N-30-F and 24-2 SUBJECT INSTRUCTIONS
Read the Subject the following instructions:
“A demonstration of the test is running now. Can you see the black
square (dot) in the center and the entire lit video screen? You need to
stare at the black dot in the center of the screen during the entire
test.”
“From time to time, you will see patterns of flickering black and white
vertical bars that will briefly appear in different areas of the screen.
The pattern will sometimes be very faint and at other times be very
distinct. You are not expected to see the bar patterns at all times.
Each time you see something flickering, press the response button
once. Can you see these patterns in the demonstration running now?
You may practice now by pressing the button to respond to the
patterns.”
“It is OK to blink, a good time to blink is when you press the
response button. If you need to rest or ask questions during the test,
you can pause the test at any time by pressing and holding down the
response button. Do you have any questions? Do you understand
how to take the test?”
“I will now start the test. There will be a few brief flashes and then the
test will begin. Press the response button once each time you see
something flickering. Please remember to stare at the black square
(dot) in the center of the screen during the entire test.”
During the test, you will see the Subject’s pupil in the black box below. Keep an eye
on the Subject’s pupil to make sure that they are maintaining fixation on the black dot
in the center of the screen and that the pupil is inside the circle in the black box. Notes
concerning the test can be added to the “Notes” box.
Participant:
SAVING & PRINTING THE FDT RESULTS
Save a CSV and PDF version of the Subject’s data. Print out the test results at the
completion of each test.
Adults ≥ 18 years
(included in Survey & Supplemental
Information)
Source:
(included in Survey & Supplemental
Information)
Language of Source:
Visual Field Reading Center, Department of Ophthalmology & Visual Science,
University of Iowa Hospitals & Clinics
Standard Automated Perimetry (SAP), Humphrey Matrix & Frequency Doubling
Technology (FTD) Visual Field Guidelines, Version date 9/9/09.
English
Version 9 – 8/10/09
Visual Field: Field Protocol
Personnel and
Training Required:
Date of SC final approval
Trained ophthalmic technician or ophthalmologist
(included in Supplemental
Information)
Equipment Needs:
(included in Supplemental
Information)
Humphrey Matrix Frequency Doubling Technology (FDT) visual field instrument. (Carl
Zeiss Meditec, Inc., Dublin, CA)
Note: This protocol for visual field uses the Humphrey Matrix Frequency Doubling
Technology (FDT) visual field instrument. If other instruments are used, the
reproducibility of the measurements should be comparable to those acquired with this
protocol. In addition, when other instruments are used to collect these measurements,
the manufacturer and model of equipment should be recorded. These other devices
may require some different steps than are described in this protocol. Investigators
should follow the equipment manufacturer’s instructions to ensure quality control.
Protocol Type:
Clinical measurement
Requirements:
Common Data
Element (CDE):
General References:
Requirements Category
Required
Major equipment
Yes
Specialized training
Yes
Specialized requirements for biospecimen
No
collection
Average time of greater than 15 minutes in an No
unaffected individual
To be completed later
None
(included in Supplemental
Information)
Protocol ID:
To be completed later
Additional Information About the Measure
Essential Data:
None
Version 9 – 8/10/09
Visual Field: Field Protocol
Related PhenX
Measures:
None
Derived Variables:
None
Keywords / Related
Concepts:
Ocular, Eye, Visual field, Peripheral vision
Collections / Used
By:
To be completed later
Measure ID:
To be completed later
Date of SC final approval
Version 9 – 8/10/09