Stratus OCT User Manual PN 2660021134133 A
Analysis Protocols
6-5
Scan Messages
The scan messages “Scan too high,” “Scan too low” and “Scan missing data” are
descriptive of what you see on screen. When the scan is too high or too low on the screen,
the analysis algorithm frequently fails. When either message appears, the operator should
repeat the scan, using the Z-Offset arrow buttons to raise or lower the scan image as
necessary. When data is missing, usually from a patient's blink, the scan image is
incomplete and unsuitable for analysis. The operator should repeat the scan, instructing
the patient not to blink during scan acquisition.
“Analysis Confidence Low” Message
The Stratus OCT detects when the scan image being analyzed has anomalies that prevent
reliable detection of the retinal layer boundaries, which reduces the reliability of the
analysis. These anomalies may be due to pathology or to an area of weak signal in the
scan. In these cases, the analysis output screen and printout will include the message:
“Analysis Confidence Low.” When it appears, the operator should use the
Edit
Layers feature (see page 6-8), or repeat the scan. This message can appear on the
analysis output windows and printouts of all quantitative analysis protocols except the
Optic Nerve Head analysis.
Layer On/Off
All the quantitative analysis output screens except the Optic Nerve Head protocol include a
Layer On checkbox, which is selected by default. When selected, the retinal layer
boundaries, detected by the analysis algorithm, appear as white lines in the analyzed scan
image. Click to clear the Layer On checkbox and hide the layer boundaries. For information
about editing the layers, see
Edit Layers on page 6-8.
Caliper On
All the quantitative analysis output screens except the Optic Nerve Head protocol include a
Caliper On checkbox. When selected, the analysis output displays a set of cross-shaped
calipers you can click and drag to measure distances directly in the analyzed scan image.
The caliper distance is reported at lower right.
Mirror Image
For line scans, click on the Mirror Image checkbox to view the mirror image of the scan and
associated graphical data. When the scan angle is between 90º (6 o’clock origin) and 270º
(12 o’clock origin), the Mirror Image checkbox is selected by default.
Note Regarding Processed Scan Images
After scan acquisition, the Stratus OCT automatically processes OCT scan images
that appear in subsequent screens, such as analysis output windows. A-scan
alignment is included in this processing. As a result of the alignment process, solid
black areas, which represent no reflectivity signal, may appear near the top and
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