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Improving precision for detecting change in the shape of the cornea in patients with keratoconus

Brunner, M, Czanner, G, Vinciguerra, R, Romano, V, Ahmad, S, Batterbury, M, Britten, C, Willoughby, CE and Kaye, SB (2018) Improving precision for detecting change in the shape of the cornea in patients with keratoconus. Scientific Reports, 8. ISSN 2045-2322

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To investigate a method for precision analysis to discriminate true corneal change from measurement imprecision in keratoconus (KC). Thirty patients with KC and 30 healthy controls were included. Coefficients of repeatability and limits of agreement (LOA) were compared using multiple measurements for inter-observer and inter-device agreement with the Pentacam HR, Orbscan IIz, and Tomey Casia SS-1000. Correlation of repeated measurements was evaluated using a linear mixed effect model (also called random effect model). A formula was derived for the theoretical expected change in precision and compared with measured change. Correlation between measurements from the same eye was small (R = 0.13). The 99.73% LOA (3 SD) of the mean of three measurements, provided better precision than 95% LOA (2 SD) of single cut-off values as expected from statistical theory for uncorrelated measurements for evidence of a significant change in corneal shape in patients with keratoconus. This enabled the determination of cut-off values for the detection of true change in corneal shape. The mean of three repeated measurements will provide better precision when there is minimal correlation. Three (rather than two) standard deviations provides a precise estimate of the LOA within or between observers and can be used as a reliable measure for identifying stage-independent corneal shape changes (progression) in keratoconus.

Item Type: Article
Uncontrolled Keywords: Science & Technology; Multidisciplinary Sciences; Science & Technology - Other Topics; COLLAGEN CROSS-LINKING; PENTACAM HR; PENETRATING KERATOPLASTY; TOMOGRAPHY; REPEATABILITY; PARAMETERS; EYES
Subjects: R Medicine > R Medicine (General)
R Medicine > RA Public aspects of medicine > RA0421 Public health. Hygiene. Preventive Medicine > RA0440 Study and Teaching. Research
Divisions: Applied Mathematics (merged with Comp Sci 10 Aug 20)
Publisher: Nature Publishing Group
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Date Deposited: 01 Oct 2018 11:19
Last Modified: 04 Sep 2021 02:23
DOI or ID number: 10.1038/s41598-018-30173-7
URI: https://researchonline.ljmu.ac.uk/id/eprint/9391
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