Zeiss CIRRUS HD-OCT 500, User Manual

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CIRRUS HD-OCT User Manual 2660021169012 Rev. A 2017-12
Criteria for Image Acceptance
7-5
Criteria for Image Acceptance
During scan review, use the following criteria to ensure that an image you have captured is
acceptable.
Fundus
• The focus should be sharp and clear, preferably with good visibility of the branching
blood vessels.
• The scan overlay should be centered on the fovea or optic nerve head.
• The Fundus image should have uniform illumination without dark corners.
• There should be few, if any, artifacts that may cast shadows on the OCT scan.
• The OCT
En Face
image should have minimal saccades and no saccades through
the area of interest (macula, for example).
OCT
• OCT scan should be complete in all windows without missing data.
• Color density should be the same from end to end.
• Signal strength should be 6 or greater.
Check for Saccades and Banding
FastTrac minimizes, but does not completely eliminate, the possibility of saccades. For cube
scans, the operator should review the OCT Fundus image to ensure there are minimal
saccades and no saccades through the area of interest (macula, for example). A saccade
can be detected by discontinuities in the appearance of the blood vessels (for example, a
horizontal shift of the vessel at a specific location).
During the course of a scan with FastTrac, the individual B-scans in a cube may be acquired
at different positions in the Z–direction (for example, tissue varies in vertical position in the
B-scan window from B-scan to B-scan). CIRRUS corrects for this motion, however the OCT
fundus image can contain artifacts from gradations in the intensity of each B-scan. These
gradations appear as horizontal lines or bands in the OCT fundus image, as shown in the
Example: Saccades