Test Strategies; Screening Test Parameters - Zeiss HUMPHREY 720i User Manual

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TEST STRATEGIES

REV.B 02/03 PN 51680-1
One of the most important test parameter settings is strategy. For both screening and threshold
testing, the strategy can affect the total test time and the precision to which the measurements
are made. The strategy also dictates whether screening test results are displayed as qualitative
(symbols) or quantitative (decibels) information. All threshold strategies yield quantitative
results. Each measures the threshold at every test point. They differ only in the method used.
Refer to Tables 4.1 and 4.2 for a more detailed explanation of screening and threshold
parameters, respectively.
Table 4.1: Screening Test Parameters
(Standard parameter settings appear in bold print)
Screening Parameter
Parameters Settings
Test Strategy Two Zone
Three Zone
Quantify Defects
Test Speed Normal
Slow
Fixation Target Central
Small Diamond
TEST PARAMETERS AND STRATEGIES
Description
For each point in the test pattern, a stimulus is
presented 6 dB brighter than the expected hill of vi-
sion. Printouts display circles (O) for seen stimuli
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and boxes ( ) for missed stimuli. Since screening
is done with an intensity 6 dB brighter than the ex-
pected threshold, missed points are known to be at
least 6 dB deep.
Same as Two Zone, except each missed point is
measured again at maximum intensity of 10,000
apostilbs (0 decibels) to determine if the defect is
absolute. Printouts display circles (O) for seen
stimuli, "X's" for relative defects, and boxes (
absolute defects.
Same as Two Zone, except the sensitivity at each
missed point is measured relative to the expected
threshold. Printouts display circles (O) for seen
stimuli, and numbers (in decibels) to indicate the
depth of any defects. The greater the number, the
lower the retinal sensitivity (deeper the defect).
Two stimulus presentation speeds are available.
The test speed may be changed while a test is in
progress. The Normal setting automatically
adjusts test speed for a slow responding patient.
Yellow light in the center of the bowl.
The Small Diamond is located below the Central tar-
get, and should be used when a patient cannot see
the central fixation light (e.g. macular degenera-
tion). The patient should look in the center of the
diamond formed by the four lights.
HUMPHREY FIELD ANALYZER II - i series
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