Zeiss CIRRUS HD-OCT 500, User Manual

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Appendix
2660021169012 Rev. A 2017-12 CIRRUS HD-OCT User Manual
A-28
Description of RNFL Parameters
The RNFL Parameters that are compared to normal limits include:
• Average RNFL Thickness around a measurement circle with 3.46 mm diameter.
• Average RNFL Thickness in 4 quadrants distributed evenly around the measurement
circle (Superior, Temporal, Inferior, and Nasal).
• Average RNFL Thickness in 12 clock–hours (30º segments of the measurement circle).
• Thickness in a TSNIT profile around the measurement circle (255 points distributed
evenly around the measurement circle, starting at the temporal most point and
traveling superior – nasal – inferior and back to temporal, or TSNIT).
• RNFL Symmetry: correlation coefficient between left eye TSNIT profile and right eye
TSNIT profile.
Age Coefficient – RNFL Thickness
Analysis of subject demographics determined that expected thickness was dependent upon
age, although the effect was small, and sometimes positive (slightly increasing thickness
with age). Thus age correction is incorporated into the calculated results. Subject ethnicity
was self–reported by the subjects in the population comprising the normative database but
was not used as a variable in constructing the RNFL and macula normative databases.
Figure A-15 below displays a scatter plot for average RNFL thickness versus age along
with the fitted regression line.
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