The effect of interrupted defocus on blur adaptation.

Autor: Khan KA; School of Optometry and Vision Science, University of Bradford, Bradford, UK., Cufflin MP; School of Optometry and Vision Science, University of Bradford, Bradford, UK., Mallen EA; School of Optometry and Vision Science, University of Bradford, Bradford, UK. E.A.H.Mallen@Bradford.ac.uk.
Jazyk: angličtina
Zdroj: Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) [Ophthalmic Physiol Opt] 2016 Nov; Vol. 36 (6), pp. 649-656.
DOI: 10.1111/opo.12323
Abstrakt: Purpose: Blur adaptation occurs when an observer is exposed to continuous defocus. However, it is unclear whether adaptation requires constant defocus, or whether the effect can still be achieved when the adaptation period is interrupted by short periods of clear vision.
Methods: The study included 12 emmetropes and 12 myopes. All observers wore full refractive correction throughout the experiment. 1D and 3D of myopic defocus was introduced using spherical convex lenses. An automated system was used to place the blurring lens before the RE for varying periods of blurred and clear vision during adaptation. Participants watched a DVD at 3 m during each 15 min trial. Visual acuity was measured using Test Chart 2000 before and after adaptation.
Results: Blur adaptation occurs to varying degrees depending on the periods of incremental blur exposure. Significant improvements in defocused visual acuity occur with continuous blur, equal blur and clear periods, as well as for longer blur periods. However, longer clear periods showed reduced adaptation and this trial is significantly different to the other three trials for both defocus levels (p < 0.001). No refractive group differences were observed for neither 1D nor 3D defocus (p = 0.58 and p = 0.19 respectively).
Conclusions: Intervening periods of clear vision cause minimal disruption to improvements in defocused visual acuity after adaptation, indicating that blur adaptation is a robust phenomenon. However, when the exposure to clear vision exceeds the defocused periods, adaptation is inhibited. This gives insight into the effects of real-world tasks on adaptation to blur.
(© 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.)
Databáze: MEDLINE
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