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Journal of Biomedical Optics

Reliability of the compensation comparison stray-light measurement method
Author(s): Joris Coppens; Luuk Franssen; L. J. van Rijn; Thomas J. T. P. van den Berg
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Paper Abstract

The compensation comparison (CC) method is a psychophysical technique to measure retinal stray light. It uses a two alternative forced choice (2AFC) measurement paradigm. The 25 binary (0 and 1) responses resulting from the 2AFC test are analyzed using maximum likelihood estimates. The likelihood function is used to give two quantities: the most likely stray-light level of the eye under investigation, and the accuracy of this estimate [called expected standard deviation (ESD)]. The CC method is used in 2422 subjects of the GLARE study. Each eye is tested twice to allow analysis of measurement repeatability. Furthermore, the large amount of responses is used to evaluate the shape of the psychometric function, for which a mathematical model is used. The shape of the psychometric function found by averaging the 0 and 1 responses fit well to the model function. Data sorted according to ESD show differences in the shape of the psychometric function between good and bad observers. These different shapes for the psychometric function are used to reanalyze the data, but the stray-light results remain virtually identical. ESD proves to be an efficient tool to detect unreliable measurements. In clinical practice, ESD may be used to decide whether to repeat a measurement.

Paper Details

Date Published: 1 May 2006
PDF: 9 pages
J. Biomed. Opt. 11(3) 034027 doi: 10.1117/1.2209555
Published in: Journal of Biomedical Optics Volume 11, Issue 3
Show Author Affiliations
Joris Coppens, The Netherlands Ophthalmic Research Institute (Netherlands)
Luuk Franssen, The Netherlands Ophthalmic Research Institute (Netherlands)
L. J. van Rijn
Thomas J. T. P. van den Berg, The Netherlands Ophthalmic Research Institute (Netherlands)

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