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dc.contributor.authorHampson, Karen M.*
dc.contributor.authorCufflin, Matthew P.*
dc.contributor.authorMallen, Edward A.H.*
dc.date.accessioned2017-06-22T15:46:10Z
dc.date.available2017-06-22T15:46:10Z
dc.date.issued2017
dc.identifier.citationHampson KM, Cufflin MP and Mallen EAH (2017) Sensitivity of Chaos Measures in Detecting Stress in the Focusing Control Mechanism of the Short-Sighted Eye. Bulletin of Mathematical Biology. 79(8): 1870–1887.en_US
dc.identifier.urihttp://hdl.handle.net/10454/12300
dc.descriptionyesen_US
dc.description.abstractWhen fixating on a stationary object, the power of the eye’s lens fluctuates. Studies have suggested that changes in these so-called microfluctuations in accommodation may be a factor in the onset and progression of short-sightedness. Like many physiological signals, the fluctuations in the power of the lens exhibit chaotic behaviour. A breakdown or reduction in chaos in physiological systems indicates stress to the system or pathology. The purpose of this study was to determine whether the chaos in fluctuations of the power of the lens changes with refractive error, i.e. how short-sighted a subject is, and/or accommodative demand, i.e. the effective distance of the object that is being viewed. Six emmetropes (EMMs, non-short-sighted), six early-onset myopes (EOMs, onset of short-sightedness before the age of 15), and six late-onset myopes (LOMs, onset of short-sightedness after the age of 15) took part in the study. Accommodative microfluctuations were measured at 22 Hz using an SRW-5000 autorefractor at accommodative demands of 1 D (dioptres), 2 D, and 3 D. Chaos theory analysis was used to determine the embedding lag, embedding dimension, limit of predictability, and Lyapunov exponent. Topological transitivity was also tested for. For comparison, the power spectrum and standard deviation were calculated for each time record. The EMMs had a statistically significant higher Lyapunov exponent than the LOMs ( 0.64±0.330.64±0.33 vs. 0.39±0.20 D/s0.39±0.20 D/s ) and a lower embedding dimension than the LOMs ( 3.28±0.463.28±0.46 vs. 3.67±0.493.67±0.49 ). There was insufficient evidence (non-significant p value) of a difference between EOMs and EMMs or EOMs and LOMs. The majority of time records were topologically transitive. There was insufficient evidence of accommodative demand having an effect. Power spectrum analysis and assessment of the standard deviation of the fluctuations failed to discern differences based on refractive error. Chaos differences in accommodation microfluctuations indicate that the control system for LOMs is under stress in comparison to EMMs. Chaos theory analysis is a more sensitive marker of changes in accommodation microfluctuations than traditional analysis methods.en_US
dc.language.isoenen_US
dc.relation.isreferencedbyhttps://doi.org/10.1007/s11538-017-0310-5en_US
dc.rights© 2017 The Authors. Published by Springer. This article is an open access publication under a Creative Commons Attribution Licence (CC BY).en_US
dc.subjectAccommodation fluctuations; Chaos theory; Power spectrum; Refractive erroren_US
dc.titleSensitivity of Chaos Measures in Detecting Stress in the Focusing Control Mechanism of the Short-Sighted Eyeen_US
dc.status.refereedyesen_US
dc.date.application2017-06-21
dc.typeArticleen_US
dc.type.versionPublished versionen_US
refterms.dateFOA2018-07-25T15:43:11Z


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