Zeiss CIRRUS HD-OCT 500, Руководство пользователя

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Appendix
2660021169012 Rev. A 2017-12 CIRRUS HD-OCT User Manual
B-10
The coefficient of variation (CV) is defined as the ratio of the standard deviation to the
mean. The coefficient of variation is useful because the standard deviation of data must
always be understood in the context of the mean of the data. For the 200x200 scans, the
CV for the sub–RPE illumination was 12.5%. For the 512x128 scans, the CV was 15.8%.
Table B-8: Repeatability and Reproducibility of Area of Sub–RPE Illumination
Automated Algorithm
Manual editing of the 200x200 scans by trained clinical personnel was carried out in cases
where the algorithm did not find the outline of the lesion accurately. Each scan was
evaluated, and the determination of whether it needed manual editing or not was made by
the designated clinical personnel.
Table B-9 illustrates that for the manual area
measurements, the repeatability limit of the 200x200 scans was considerably lower than
the automated measurements (0.6365 and 2.4885 mm
2
respectively). For the manually
edited scans, the area of sub–RPE illumination had a coefficient of variation of 4.3% which
was much lower compared to that of the automated algorithm.
Table B-9: Repeatability and Reproducibility of Area of Sub–RPE Illumination
Manually Edited
Scan
Repeatability Reproducibility
Repeatability
SD (mm
2
)
Repeatability
Limit
a
(mm
2
)
Reproducibility SD
(mm
2
)
Reproducibility
Limit
b
(mm
2
)
CV
c
%
200x200 Scan 0.8887 2.4885 0.9450 2.6460 12.5%
512x128 Scan 0.8683 2.4313 1.0317 2.8889 15.8%
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 individual measurements using different operators and instru-
ments. Per ISO 5725–1 and ISO 5725–6, Reproducibility Limit = 2.8 x Reproducibility SD.
c. CV = Coefficient of variation = SD ÷ Mean.
Scan
Repeatability Reproducibility
Repeatability
SD (mm
2
)
Repeatability
Limit
a
(mm
2
)
Reproducibility SD
(mm
2
)
Reproducibility
Limit
b
(mm
2
)
CV
c
%
200x200 Scan 0.2273 0.6365 0.3823 1.0705 4.3%
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 individual measurements using different operators and instru-
ments. Per ISO 5725–1 and ISO 5725–6, Reproducibility Limit = 2.8 x Reproducibility SD.
c. CV = Coefficient of variation = SD ÷ Mean.