Effects of Prism Eyeglasses on Objective and Subjective Fixation Disparity
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[Original articel also available: http://www.plosone.org/article/related/info%3Adoi%2F10.1371%2Fjournal.pone.0138871]
Authors
Author (Corporation)
Publication date
02.10.2015
Typ of student thesis
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Type
01A - Journal article
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Parent work
PLOS ONE
Special issue
DOI of the original publication
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Series
Series number
Volume
2015
Issue / Number
10
Pages / Duration
1-29
Patent number
Publisher / Publishing institution
Public Library of Science
Place of publication / Event location
San Francisco
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Practice partner / Client
Abstract
In optometry of binocular vision, the question may arise whether prisms should be included in eyeglasses to compensate an oculomotor and/or sensory imbalance between the two eyes. The corresponding measures of objective and subjective fixation disparity may be reduced by the prisms, or the adaptability of the binocular vergence system may diminish effects of the prisms over time. This study investigates effects of wearing prisms constantly for about 5 weeks in daily life. Two groups of 12 participants received eyeglasses with prisms having either a base-in direction or a base-out direction with an amount up to 8 prism
diopters. Prisms were prescribed based on clinical fixation disparity test plates at 6 m. Two dependent variables were used: (1) subjective fixation disparity was indicated by a perceived offset of dichoptic nonius lines that were superimposed on the fusion stimuli and (2) objective fixation disparity was measured with a video based eye tracker relative to monocular calibration. Stimuli were presented at 6 m and included either central or more peripheral fusion stimuli. Repeated measurements were made without the prisms and with the prisms after about 5 weeks of wearing these prisms. Objective and subjective fixation disparity were correlated, but the type of fusion stimulus and the direction of the required prism may play a role. The prisms did not reduce the fixation disparity to zero, but induced significant changes in fixation disparity with large effect sizes. Participants receiving base-out prisms showed hypothesized effects, which were concurrent in both types of fixation disparity. In participants receiving base-in prisms, the individual effects of subjective and objective effects were negatively correlated: the larger the subjective (sensory) effect, the smaller the objective (motor) effect. This response pattern was related to the vergence adaptability, i.e. the individual fusional vergence reserves.
Keywords
fixation disparity, prism, vision, human, binocular vision, eye tracking
Subject (DDC)
600 - Technik, Medizin, angewandte Wissenschaften
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ISBN
ISSN
1932-6203
Language
English
Created during FHNW affiliation
Yes
Strategic action fields FHNW
Publication status
Published
Review
Peer review of the complete publication
Open access category
License
Citation
SCHROTH, Volkhard, Roland JOOS und Wolfgang JASCHINSKI, 2015. Effects of Prism Eyeglasses on Objective and Subjective Fixation Disparity. PLOS ONE. 2 Oktober 2015. Bd. 2015, Nr. 10, S. 1–29. DOI 10.1371/journal.pone.0138871. Verfügbar unter: https://doi.org/10.26041/fhnw-68