Optimal image sample size for corneal nerve morphometry

Vagenas, Dimitrios, Pritchard, Nicola, Edwards, Katie, Shahidi, Ayda M., Sampson, Geoff P., Russell, Anthony W., Malik, Rayaz A. and Efron, Nathan (2012) Optimal image sample size for corneal nerve morphometry. Optometry and Vision Science, 89 5: 812-817. doi:10.1097/OPX.0b013e31824ee8c9

Author Vagenas, Dimitrios
Pritchard, Nicola
Edwards, Katie
Shahidi, Ayda M.
Sampson, Geoff P.
Russell, Anthony W.
Malik, Rayaz A.
Efron, Nathan
Title Optimal image sample size for corneal nerve morphometry
Journal name Optometry and Vision Science   Check publisher's open access policy
ISSN 1040-5488
Publication date 2012-05
Sub-type Article (original research)
DOI 10.1097/OPX.0b013e31824ee8c9
Volume 89
Issue 5
Start page 812
End page 817
Total pages 6
Place of publication Philadelphia, PA, United States
Publisher Lippincott Williams & Wilkins
Collection year 2013
Language eng
Formatted abstract
Purpose. Arbitrary numbers of corneal confocal microscopy images have been used for analysis of corneal subbasal nerve
parameters under the implicit assumption that these are a representative sample of the central corneal nerve plexus. The
purpose of this study is to present a technique for quantifying the number of random central corneal images required to
achieve an acceptable level of accuracy in the measurement of corneal nerve fiber length and branch density.
Methods. Every possible combination of 2 to 16 images (where 16 was deemed the true mean) of the central corneal
subbasal nerve plexus, not overlapping by more than 20%, were assessed for nerve fiber length and branch density in 20
subjects with type 2 diabetes and varying degrees of functional nerve deficit. Mean ratios were calculated to allow
comparisons between and within subjects.
Results. In assessing nerve branch density, eight randomly chosen images not overlapping by more than 20% produced
an average that was within 30% of the true mean 95% of the time. A similar sampling strategy of five images was 13%
within the true mean 80% of the time for corneal nerve fiber length.
Conclusions. The “sample combination analysis” presented here can be used to determine the sample size required for
a desired level of accuracy of quantification of corneal subbasal nerve parameters. This technique may have applications
in other biological sampling studies.
Keyword Corneal confocal microscopy
Sampling methodology
Corneal nerves
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Medicine Publications
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