Zeiss CIRRUS HD-OCT 500, Руководство пользователя

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CIRRUS HD-OCT User Manual 2660021169012 Rev. A 2017-12
Appendix
A-21
In practice, clinicians and operators should quantitatively and qualitatively review scans
before comparing them to normal ranges.
Data Analysis
Data was analyzed using the proprietary ganglion cell analysis segmentation algorithm to
obtain seven main summary parameters, all expressed in micrometers: Average GCL + IPL
thickness, six sectoral thickness values, where the sectors are derived from 60º segments of
an elliptical annulus with inner minor axis radius of 0.5 mm and outer minor axis radius of
2.0 mm, stretched by 20% in the horizontal direction to get the major axes. The sectors are
shown below:
OS Sectors OD Sectors
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The seventh parameter is the minimum average value of a set of 360 spokes, where each
average represents the average of the pixels along that spoke that lie within the
measurement annulus. The minimum is selected because the thinnest portion of the
ganglion cell plus inner plexiform layers in the perifoveal region is considered likely to
indicate damage to the ganglion cells.
Results
The descriptive statistics for Ganglion Cell Analysis parameters based on 282 normal eyes
are reported in
Table A-3 below.
Table A-3 Normal Values for CIRRUS Ganglion Cell Analysis Measurements in the
Sample Population ( μ m)
Factors that Affect CIRRUS Ganglion Cell Analysis Normative
Ranges
The normal ranges described above do not take into account differences that may be
present due to age, ethnicity, axial length, refraction, optic disc area, or signal strength. In
regression analysis, we found that signal strength and age were the two continuous
parameters with the greatest effect on the Ganglion Cell Analysis parameters. All effects
Average GCL + IPL
Thickness
Sector 1 Sector 2 Sector 3 Sector 4 Sector 5 Sector 6
Minimum Average Axial
Thickness
Mean 84.7 82.9 86.4 86.8 85.3 83.2 83.8 82.1
Std 7.1 6.3 7.9 8.3 9.0 7.8 6.5 6.9
Min 67.7 68.0 67.0 65.0 62.0 62.0 68.0 53.2
Max 104.2 102.0 113.0 112.0 111.0 109.0 106.0 101.8