Performance Of Cirrus Hd-Oct Rnfl Analysis - Zeiss CIRRUS HD-OCT 500 User Manual

B-20
CIRRUS HD-OCT Repeatability
Repeatability
SD (μm)
4.08
a. Repeatability Limit is the upper 95% limit for the difference between repeated results. Per ISO 5725–1 and ISO 5725–6, Repeatability Limit = 2.8 x
Repeatability SD
b. Reproducibility Limit is the upper 95% limit calculated for the difference between results repeated using different operators. Each subject was imaged
three times during a single visit by each of three operators. Per ISO 5725–1 and ISO 5725–6, Reproducibility Limit = 2.8 x Reproducibility SD.
2660021169012 Rev. A 2017-12
Appendix
Table B-18: Repeatability and Reproducibility of Central Corneal Thickness
CIRRUS HD-OCT Reproducibility
Repeatability Reproducibility
a
Limits (μm) SD (μm)
11.42
Comparison of CIRRUS HD-OCT and Ultrasound Pachymetry in Central Corneal
Thickness Measurements
Table B-19
between CIRRUS HD-OCT and ultrasound pachymetry. The negative difference means that
the CIRRUS CCT measurement is thinner than the ultrasound CCT measurement. This data
was taken from a total of 50 eyes enrolled in one site measured by a single operator for
each device.
Table B-19: Difference in Central Corneal Thickness measurement Between CIRRUS
HD-OCT and Ultrasound Pachymetry
CIRRUS CCT– Ultrasound
pachymetry CCT (μm)
OCT devices in general measure thinner than ultrasound pachymetry. The Visante User
Manual reports an average measurement difference of 15.1 μm. In the literature, reported
differences between OCT and ultrasound pachymetry range from 11.64 to 49.4 μm (see
References below).

Performance of CIRRUS HD-OCT RNFL Analysis

Repeatability and Reproducibility
CZMI performed an in–house study on normal subjects to determine the inter–visit and
inter–instrument repeatability of CIRRUS RNFL thickness measurements. The repeatability
and reproducibility (including effects of multiple visits and multiple instruments), along
with the coefficient of variability, are shown in Table B-20 on page B-21. Similar results
were also found in an independent study, which reported a coefficient of variability of
1.5% in normal subjects and 1.6% in patient eyes
2. Vizzeri, G, Weinreb, RN, Gonzalez-Garcia, AO, Bowd, C, Medeiros, F, Sample, PA, Zangwill, LM: Agreement between spec-
tral-domain and time-domain OCT for measuring RNFL thickness, Br J Ophthalmol, March 2009.
Reproducibility
b
Limits (μm)
4.23 11.84
shows the mean difference in central corneal thickness measurements
Mean Difference SD
–9.06 5.63
(μm)
Mean Thickness
Phase Phase Overall
I II
544.25 532.25 538.25
95% CI of the Difference
Lower Upper
–10.66 –7.46
2 .
CIRRUS HD-OCT User Manual