Zeiss HUMPHREY 720i, Руководство пользователя

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7-10 STATPAC ANALYSIS & PRINTING RESULTS
REV. B 02/03 PN 51680-1 HUMPHREY FIELD ANALYZER II -
i
series
The change analysis Like the Overview printout, the Change Analysis printout shows analyses of up to sixteen
printout (16) test results on one sheet. In this case, STATPAC gives you an analytical summary of
changes in the patient’s visual field from the time of the earliest test you have included in
the summary to the time of the most recent test included.
STATPAC presents the Change Analysis in the form of a box plot analysis of test results, a
summary of four global indices, and a linear regression analysis of Mean Deviation. The
indices are the same four presented in the Single Field Analysis, but this time they are plotted
over time to indicate changes in the patient’s visual field.
The box plot Box plots are helpful in making a quick determination about the nature and extent of
visual field changes over time. The box plot is a modified histogram that gives a five-number
summary of the test results. It displays a concise summary of the Total Deviation decibel value
for each test, showing the median, the two extreme values and the 15th and 85th percentile
deviations.
The summary is made up of the differences at each tested point between the patient’s measured
field and the STATPAC age-corrected reference field. STATPAC plots the extreme values of these
differences (the 100th and zero percentile, or the end points of the line shown at (b) in Figure
7.4) as well as the median difference (the three dark lines shown at (a) inside the box), and
the 85th and 15th percentile differences (the top and bottom of the box).
Look at the box plot in Figures 7.4 and 7.5. The four things to note are:
1. The overall shape of the box, how elongated or compact it is.
2. The location of the three dark lines inside the box that indicate the median (a).
3. The top and bottom end points of the line along which the box lies (b).
4. Where the patient’s box is plotted against the normal scale on the left of the printout.
(b) 100% best value= average maximum positive
deviation from age normal
85% 85th percentile
(a) 50% median
15% 15th percentile
(b) 0% worst value= average maximum negative
deviation from age normal
Figure 7.4: The Box Plot
To facilitate interpreting your patient’s field results, a “normal” box is presented to the left of
the patient’s scale (see Figure 7.5). This is the mean of the boxes derived from the normals
data on which the STATPAC model is based.
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