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Factors Influencing Pseudo-Accommodation—The Difference between Subjectively Reported Range of Clear Focus and Objectively Measured Accommodation Range

1
Optometry and Vision Science Research Group, Life and Health Sciences, Aston University, Birmingham B4 7ET, UK
2
Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
3
Department of Clinical Research, Vista Ircovisión Oftalmólogos, 30008 Murcia, Spain
4
Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, UK
5
Department of Biomedical Engineering, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland
*
Author to whom correspondence should be addressed.
Vision 2019, 3(3), 34; https://doi.org/10.3390/vision3030034
Received: 28 March 2019 / Revised: 6 June 2019 / Accepted: 20 June 2019 / Published: 28 June 2019
(This article belongs to the Special Issue Physiological Optics of Accommodation and Presbyopia)
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Abstract

The key determinants of the range of clear focus in pre-presbyopes and their relative contributions to the difference between subjective range of focus and objective accommodation assessments have not been previously quantified. Fifty participants (aged 33.0 ± 6.4 years) underwent simultaneous monocular subjective (visual acuity measured with an electronic test-chart) and objective (dynamic accommodation measured with an Aston open-field aberrometer) defocus curve testing for lenses between +2.00 to −10.00 DS in +0.50 DS steps in a randomized order. Pupil diameter and ocular aberrations (converted to visual metrics normalized for pupil size) at each level of blur were measured. The difference between objective range over which the power of the crystalline lens changes and the subjective range of clear focus was quantified and the results modelled using pupil size, refractive error, tolerance to blur, and ocular aberrations. The subjective range of clear focus was principally accounted for by age (46.4%) and pupil size (19.3%). The objectively assessed accommodative range was also principally accounted for by age (27.6%) and pupil size (15.4%). Over one-quarter (26.0%) of the difference between objective accommodation and subjective range of clear focus was accounted for by age (14.0%) and spherical aberration at maximum accommodation (12.0%). There was no significant change in the objective accommodative response (F = 1.426, p = 0.229) or pupil size (F = 0.799, p = 0.554) of participants for levels of defocus above their amplitude of accommodation. Pre-presbyopes benefit from an increased subjective range of clear vision beyond their objective accommodation due in part to neural factors, resulting in a measured depth-of-focus of, on average, 1.0 D. View Full-Text
Keywords: subjective range of focus; objective accommodation; depth of focus; aberrations; pupil size; tolerance to blur; presbyopia subjective range of focus; objective accommodation; depth of focus; aberrations; pupil size; tolerance to blur; presbyopia
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Dhallu, S.K.; Sheppard, A.L.; Drew, T.; Mihashi, T.; Zapata-Díaz, J.F.; Radhakrishnan, H.; Iskander, D.R.; Wolffsohn, J.S. Factors Influencing Pseudo-Accommodation—The Difference between Subjectively Reported Range of Clear Focus and Objectively Measured Accommodation Range. Vision 2019, 3, 34.

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