Humphrey Field Analyzer II-
i
series User Manual 2660021145640 A
Guided Progression Analysis (GPA)
8-11
GPA Alert
The GPA Alert (Figure 8.4) assists you in recognizing deterioration
in consecutive tests. Note that the
GPA Alert pertains to the eye as a whole, not to specific poin
ts in the visual field. In cases where 3
or more points show statistically significant deterioration in at least 2 consecutive tests, the
progression analysis indicates “Possible Progression.” In cases where 3 or more points show
statistically significant deterioration in at least 3 consecutive tests, the progression analysis indicates
“Likely Progression.” When neither of the foregoing conditions applies, a message of “No
Progression Detected” is displayed.
VFI Plot
The VFI Plot (Figure 8.3) graphs the VFI values of all exams included in
GPA analysis as a function of
the patient’s age. VFI values from Full Threshold e
xams are represented by open squares, and VFI
values from SITA exams are represented by filled squares. Located in the center of the GPA Summary
report or the lower-left portion of the Baseline page of the Full GPA and GPA Last 3 Follow-up
reports, the VFI Plot provides a linear regression analysis of the VFI over time when appropriate. A
minimum of 5 exams over 2 years or more must be included in GPA for the linear regression results
to be presented. In addition, the linear regression line will not be drawn if the slope of the line is
positive. Finally, this line will also not be drawn when the 95% confidence limit on the measured
slope is greater than 5%.
Note: The regression line slope may be positive due to st
atistical uncertainty or the learning effect.
To the right of the VFI Plot is the VFI Bar, a histog
ram that indicates the patient’s current VFI value.
In addition, when the results of the regression analysis are displayed, the VFI Bar will also
graphically indicate the 2 to 5 year projection of the linear regression line, shown as a broken line.
The length of projection is equal to the number of years of GPA data that is available, up to a
maximum projection time of 5 years.
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