The relationship between CA/C ratio and individual differences in dynamic accommodative responses while viewing stereoscopic images


The oculomotor synergy as expressed by the CA/C and AC/A ratios was investigated to examine its influence on our previous observation that whereas convergence responses to stereoscopic images are generally stable, some individuals exhibit significant accommodative overshoot. Using a modified video refraction unit while viewing a stereoscopic LCD, accommodative and convergence responses to balanced and unbalanced vergence and focal stimuli (BVFS and UBVFS) were measured. Accommodative overshoot of at least 0.3 D was found in 3 out of 8 subjects for UBVFS. The accommodative response differential (RD) was taken to be the difference between the initial response and the subsequent mean static steady-state response. Without overshoot, RD was quantified by finding the initial response component. A mean RD of 0.11 +/- 0.27 D was found for the 1.0 D step UBVFS condition. The mean RD for the BVFS was 0.00 +/- 0.17 D. There was a significant positive correlation between CA/C ratio and RD (r = +0.75, n = 8, p <0.05) for only UBVFS. We propose that inter-subject variation in RD is influenced by the CA/C ratio as follows: an initial convergence response, induced by disparity of the image, generates convergence-driven accommodation commensurate with the CA/C ratio; the associated transient defocus subsequently decays to a balanced position between defocus-induced and convergence-induced accommodations.

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Divisions: College of Health & Life Sciences > School of Optometry > Optometry
College of Health & Life Sciences > School of Optometry > Optometry & Vision Science Research Group (OVSRG)
College of Health & Life Sciences
College of Health & Life Sciences > School of Optometry > Vision, Hearing and Language
Additional Information: Creative Commons Attribution Non-Commercial No Derivatives License
Uncontrolled Keywords: ocular accommodation,adult,ocular convergence,female,humans,male,motion perception,photic stimulation,vision disparity,binocular vision,young adult,Ophthalmology,Sensory Systems
Publication ISSN: 1534-7362
Last Modified: 12 Apr 2024 07:08
Date Deposited: 11 Mar 2019 18:19
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
http://www.jour ... content/9/13/21 (Publisher URL)
PURE Output Type: Article
Published Date: 2009-12-30
Authors: Fukushima, Tetsuya
Torii, Masahito
Ukai, Kazuhiko
Wolffsohn, James S (ORCID Profile 0000-0003-4673-8927)
Gilmartin, Bernard

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