Zeiss Humphrey II-i series, Руководство пользователя

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Reference to Older Test Strategies
Humphrey Field Analyzer II-
i
series User Manual 2660021145640 A
L-8
second column. These are the only two data presentations given for the two Baseline tests. Just
above them is printed a message indicating whether the results of the glaucoma hemifield test
(GHT) were within normal limits, outside normal limits, or borderline. The mean deviation from
normal for this test is printed between the graytone and the total deviation plot.
For each of up to fourteen (14) Follow-up tests there are two more test result analyses: the change
from Baseline plot (third column), and its associated probability map (fourth column). The change
from Baseline plot in the third column subtracts the Baseline average Total Deviation from the
Follow-up Total Deviation result and indicates changes at each tested point in dB notation. If, for
example, a point is indicated with -6, this means that the tested point was 6 dB lower than the
Baseline for the same point. A zero (0) means no change from Baseline. All results use
age-corrected values over the Follow-up period.
The Change Probability Map
The change probability map in the fourth column gives the statistical significance of the decibel
changes shown in the change from Baseline plot. It compares the changes between the Baseline
and Follow-up fields to the inter-test variability typical of stable glaucoma patients and then shows
a plot of point locations which have changed significantly. A solid triangle identifies a degree of
deterioration found less than 5% of the time at that location in medically stable glaucoma patients,
that is, deterioration significant at the 5% level. An open triangle identifies improvement significant
at the 5% level. Points not changing by a significant amount are indicated by a single, solid dot.
Note: The open triangle also is used on the Guided Progression Analysis printouts, where it indicates
a deteriorating point. Be careful not to confuse these symbols if you use both analysis programs. For
further discussion of GPA, please refer to
Chapter (8), "Guided Progression Analysis (GPA)."
An X signifies that the program was unable to determine whether the encountered change was
significant or not. This occurs mainly with deepening field defects which were already quite deep at
Baseline. The finite amount of empirical data available to us and the practical limitation of the
maximum attainable brightness of the instrument make it difficult to obtain exact significance limits
for deterioration in points which are already highly depressed.
The very same reasons, finite amount of data and limits to the maximum brightness, also make it
difficult to determine change with certainty in fields where the mean deviation from normal exceeds
-15. In addition, variability is extremely large in highly disturbed fields (MD < -15). Since variability
increases with increasing MD in this range, STATPAC analysis can only verify stability, not
deterioration or improvement. STATPAC printouts carry the message AVERAGE MEAN DEVIATION OF
ALL TESTS TOO LOW when the average MD of Baseline and Follow-up tests is lower than -15.
Change in Mean Deviation
STATPAC also evaluates the significance of change in mean deviation over time. The objective is to
highlight those clinical cases where the MD changes by more than is typically observed in stable
glaucoma patients. The amount of change in decibels is printed under the message MD Change. If
the MD change is significant at the 10%, 5%, or 2.5% level, that p value is printed along with a
solid triangle to indicate degradation or an open triangle to indicate improvement. If the amount of
change is not judged to be significant, the words “Not Significant” follow the decibel value.