Zeiss CIRRUS HD-OCT 500, User Manual

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CIRRUS HD-OCT User Manual 2660021169012 Rev. A 2017-12
Posterior Segment
8-15
Registration Review
Registration between the two Fundus images may be compared by selecting the
Registration Review button:
. The results appear on a popup screen, as shown in
Figure 8-10
.
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In Figure 8-10 , Image 1 is the an image taken from (an earlier) previous exam. Image 2 is
the image from the most recent visit. The bottom image is an overlay of the two exams. The
image slider allows you to adjust the view of the overlaid images: slide to the left to view
Image 1, to the right for Image 2. Black borders might be seen in Image 2. This is the area
of the second image that does not correspond to the first image when the two images
were registered to each other.
Registration Successful
The “Registration Succeeded” message along with the green flag indicate that the two
chosen images did register reliably. A red flag appears if the registration fails. This could be
caused by weak signal strength, poor alignment, opacities, large differences in the scan
areas,
or larger differences in retinal anatomy. When that occurs, you may attempt to use
Manual registration by selecting from the Registration dialog box or, if available, select
another image for comparison. In the Registration dialog box, you may also choose No
Registration.
NOTE: The indication for success or failure of the registration algorithm is based on a
cross-correlation metric computed from the two images after registration. A threshold is
used on this metric to make a binary decision of success or failure.