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8-33
Posterior Segment
These plots are generated using linear regression in order to calculate the rate of loss.
Confidence bands for the regression line are also shown. They are determined based on
comparing the variability in the data to the rate of change. The slope (rate of change) is
displayed in micrometers/year with 95% confidence interval values. For example, with a
slope of –3.9 ±1.1, there is 95% confidence based on statistical analysis that the slope is
between –2.8 and –5.0 μm/year. This is shown graphically in the shaded gray area.
The graphical plots will show a rate of change and 95% confidence limits around that rate
of change whenever at least 4 exams that span at least 2 years are loaded. If there are
fewer than 4 scans loaded, or if there is less than two years between the first baseline and
the current scan, no rate of change analysis will be provided.
NOTE: Linear regression fits the data to a linear model, assuming that the measurements
are independent and normally distributed, and that variability does not depend on the size
of the measurement. If the observed measurements do not change linearly, the rate of
change may still provide information about how the patient has changed during the period
of examination, but it should not be used to predict future change. Linear regression is a
statistical analysis, and should not replace clinical evaluation of the patient's status and
progress.
Summary Charts
Summary charts
("RNFL & ONH Summary Chart" on page 8-36
for RNFL,
"GCL+IPL Summary Chart" on page 8-39
for Ganglion Cell) display color-coded
summary boxes that provide alert if significant change has been detected.
CIRRUS HD-OCT User Manual
2660021169012 Rev. A 2017-12
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Table of Contents
Troubleshooting
