Humphrey FDT User Manual
2660021149532 Rev. B 2015-11
Operation
3-13
Understanding the Screening C-20 and N-30 Test Results
A plot of the 17 visual field locations tested will be printed (see samples on the following
pages) and displayed on the Operator LCD Display for the supra-threshold SCREENING
C-20 TEST for each eye tested. There are 19 visual field locations tested with the
SCREENING N-30 TEST. Each test location will be either clear white or will have one of
three possisble levels of shading.
When reviewing the results of the visual field test, careful consideration must be given to
the reliability indicators (catch trials). The following two test reliability indicators appear on
the printed report and Operator LCD Display for the screening test. They are an important
measure of patient reliability in taking the test (and of the reliability of the results). They are
indicated as a ratio of the number responded to the number presented. For example, 1/3
indicates that the patient responded to 1 of the 3 catch trials presented.
FIXATION ERRORS - The ratio of the number of times the patient responded to a target
placed in the blind spot versus the total number of times fixation was tested (i.e., total
number of targets placed in the blind spot). Three FIXATION catch trials will be randomly
presented for each eye. Fixation errors indicate the patient is not maintaining good fixation
during the test, is misaligned, or does not understand the test.
FALSE POSITIVE ERRORS - The ratio of the number of times the patient responded to a
“pause” in the testing sequence (i.e., no target presented) versus the total number of
“pauses” in the testing sequence. Three FALSE POSITIVE catch trials will be randomly
presented for each eye. False positive errors indicate the patient is pressing the Button
even if the patient doesn’t see any patterns or does not understand the test.
A
“WITHIN NORMAL LIMITS” — The patient responded positively (on either the
first or second opportunity) when tested at the contrast level that 99% (P > =
1%) of normal subjects of the same age would respond to for the test location
with this shading.
B
“MILD RELATIVE LOSS” — The patient failed to respond positively when tested
at the 1% age normative contrast level (P = 1%) after being given 2
opportunities to do so (the instrument will re-test any point missed at the 1%
age normative level a second time) for the test location with this shading.
C
“MODERATE RELATIVE LOSS” — The patient failed to respond positively after
being given 3 opportunities to do so; twice at the 1% age normative contrast
level (P = 1%) and a third time at the 0.5% age normative contrast level (P =
0.5%) for the test location with this shading.
D
“SEVERE LOSS” — The patient failed to respond positively after being given 4
opportunities to do so for the test locations with this shading; the 3
opportunities listed above and a fourth at the maximum contrast level of the
instrument.
A
B
C
D
FIXATION ERRS: 0/3
FALSE POS ERRS: 0/3
Содержание Humphrey FDT 710
Страница 1: ...Humphrey FDT Model 710 User Manual...
Страница 19: ...Humphrey FDT User Manual 2660021149532 Rev B 2015 11 Introduction 2 7 Patient Video Screen Patterns...
Страница 20: ...Introduction Humphrey FDT User Manual 2660021149532 Rev B 2015 11 2 8...
Страница 38: ...Operation Humphrey FDT User Manual 2660021149532 Rev B 2015 11 3 18 Screening C 20 Test Result Sample...
Страница 39: ...Humphrey FDT User Manual 2660021149532 Rev B 2015 11 Operation 3 19 Threshold C 20 Test Results Sample...
Страница 40: ...Operation Humphrey FDT User Manual 2660021149532 Rev B 2015 11 3 20 Threshold N 30 Test Results Sample...
Страница 50: ...Service Information Humphrey FDT User Manual 2660021149532 Rev B 2015 11 5 2...
Страница 53: ......