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A-10
Methods
2660021169012 Rev. A 2017-12
Appendix
Data Collection
In summary, 282 subjects were qualified as normal subjects, enrolled in the NDB study,
and included for the RNFL database. Data from the same scans was analyzed and
evaluated to determine the normal range of ONH parameters. The normative database
does not have subjects with refractive errors outside the –12.00 D to +8.00 D range.
Therefore, the analysis below should be applied with caution to subjects with refractive
errors outside the –12.00 D to +8.00 D range.
Scan Selection Criteria
The scans were reviewed for image quality as part of the original study. One best quality
scan for each scan type was chosen for each subject per eye. Scans having the following
characteristics were excluded from the normative database:
• Signal Strength of 5 or lower.
• Large eye motion during image acquisition, resulting in a saccade that was within the
central 80% of the scan area.
• Area of data loss greater than 10% at the edge of the scan area.
• Presence of floater(s) obscuring macular area on Macular cube scans or measurement
circle on Optic Disc cube scans.
Scans were reviewed again after processing with the optic nerve head analysis algorithm,
to ensure that no floaters impacted the optic nerve head region, and to ensure that the
optic nerve head data was within the axial field of view of the scan. For three eyes a new
scan was selected to ensure acceptable ONH as well as RNFL results.
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 optic nerve head analysis algorithm to obtain five
main summary parameters: Disc Area (mm
to Disc Ratio, Rim Area (mm
2
), and Cup Volume (mm
2
), Average Cup to Disc Ratio (CDR), Vertical Cup
3
).
CIRRUS HD-OCT User Manual
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