Zeiss CIRRUS HD-OCT 500, User Manual

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CIRRUS HD-OCT User Manual 2660021169012 Rev. A 2017-12
Appendix
A-13
Presentation of Normative Limits
Figure A-7 shows the ONH and RNFL OU Analysis with normative limits applied to the
ONH parameters of Rim Area, Cup to Disc Ratio, Vertical Cup to Disc Ratio, and Cup
Volume, as well as to the neuroretinal rim (NR) profile.
Because each eye may have a different disc area, the normal limits shown behind the NR
profile depend on which eye is selected for comparison. If OU is selected, normal limits
appropriate to the average disc area are shown.
If the disc area is larger than 2.5 mm
2
or smaller than 1.3 mm
2
, then normative limits are
not applied because not enough data is available in the database to determine the limits.
In this case the area behind the number or the NR plot is shown as gray. In addition,
Average and Vertical C/D Ratios less than or equal to 0.25 will be shown as gray.
Conclusion
The CIRRUS HD-OCT optic nerve head normative database was created using data from
subjects that were deemed representative of a normal population. To establish reference
values, the scans acquired as part of the CIRRUS HD-OCT RNFL normative databases were
analyzed using a optic nerve head segmentation algorithm. The doctor can use the
normative database to compare individual patient measurements to those acquired in a
normal population.