Zeiss CIRRUS HD-OCT 500, User Manual

Page: 84 / 352

Anterior Segment Scans
2660021169012 Rev. A 2017-12 CIRRUS HD-OCT User Manual
6-12
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NOTE: For the Anterior Segment Cube 512x128 and Anterior Segment 5 Line Raster scans,
the instrument focuses the OCT beam onto the anterior segment. The OCT beam scans in
an arc to allow the curved cornea to better fit into the 2mm scan depth. This will cause the
cornea to appear flat in the display during alignment and acquisition. This effect is partially
corrected for after acquisition, so the cornea will appear with the expected curvature
during review and analysis.
HD Angle Scan
The HD Angle is the preferred scan for imaging the anterior chamber angle. It gives the
highest resolution and greatest detail of the iridocorneal angle. Wide Angle-to-Angle and
Anterior Chamber scans may also be used for anterior chamber angle analysis. All three
scans have an angle measurement tool (see
"In HD Angle Analysis" on page 8-53 ).
The HD Angle and Wide Angle-to-Angle scans also have an iridocorneal (IC) angle tool to
measure iridocorneal angle features (see
"Angle Measurements" on page 8-53 ).
This scan, available for anterior segment scans only, generates a speckle–reduced raster
scan at a depth of 2.9 mm using 20 B-scans, each composed of 1024 A scans. The scan is
6.0 mm in length, with an adjustable angle from –89 to 90 degrees. The scan highlights
one iridocorneal angle, which can be measured via specialized angle calipers in the HD
Angle Scan Analysis (
"In HD Angle Analysis" on page 8-53
).
The Acquire screen displays the position of the HD Angle scan pattern on the live iris image
and displays the OCT B-scan image on the right.