Zeiss HUMPHREY 720i User Manual - page 78

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TEST PARAMETERS AND STRATEGIES

REV.B 02/03 PN 51680-1

HUMPHREY FIELD ANALYZER II - 

i series

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

Description

Parameters

Settings

Test Strategy

Two Zone

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

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.

Three Zone

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 (

■

) for

absolute defects.

Quantify 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).

Test Speed

Normal

Two stimulus presentation speeds are available.

Slow

The test speed may be changed while a test is in

progress. The Normal setting automatically

adjusts test speed for a slow responding patient.

Fixation Target

Central

Yellow light in the center of the bowl.

Small Diamond

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.

TEST STRATEGIES

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