Related Experiment Video
Updated: Feb 17, 2026

Three Dimensional Vestibular Ocular Reflex Testing Using a Six Degrees of Freedom Motion Platform
Published on: May 23, 2013
Effect of Induced Vertical Disparity on Horizontal Fusional Reserves
Hamed Momeni-Moghaddam1,2, Abbas-Ali Yekta2,3, James Kundart4
1a Health Promotion Research Center , Zahedan University of Medical Sciences , Zahedan , Iran.
Purpose:
The aim of this study was to investigate the effects of induced vertical disparity on horizontal fusional reserves at near.
Materials And Methods:
In 170 healthy subjects wearing best corrective refraction, the negative and positive horizontal fusional reserves were measured with base-in (BI) and base-out (BO) prisms, respectively, in the presence of 0.5 prism diopters (∆) and 1∆ vertical prisms placed in trial frames in front of the right eye. The prism power was slowly increased step by step until the subject reported sustained blur, break, and recovery. These were compared to horizontal fusional reserves in the same subjects without a vertical prism. Data were analyzed in SPSS.17 software using a repeated measures ANOVA.
Results:
Induced vertical disparity decreased negative fusional reserves (NFR) horizontally and was more significant with 1∆ vertical disparity (P<0.001). There were significant differences between the blur (P<0.001), break (P<0.001), and recovery (P<0.001) for NFR before and after induced vertical disparity and no significant difference between blur (P=0.173) and recovery points (P=0.261) with a marginal difference for break points (P=0.045) for the positive fusional reserves (PFR).
Conclusion:
Inducing vertical disparity even with small magnitudes affects all 3 aspects (blur, break, and recovery) of horizontal negative fusional reserves while only break is affected in positive fusional reserves. These changes are statistically significant but do not seem to be clinically significant except for cases accompanied by symptoms.
More Related Videos
05:02Using Unidirectional Rotations to Improve Vestibular System Asymmetry in Patients with Vestibular Dysfunction
Published on: August 30, 2019
05:36Central and Divided Visual Field Presentation of Emotional Images to Measure Hemispheric Differences in Motivated Attention
Published on: November 16, 2017
Related Concept Videos
Influence of Earth's Curvature and Atmospheric Refraction on Leveling
Shear on the Horizontal Face of a Beam Element
Three-Dimensional Force System:Problem Solving
To solve a three-dimensional force system, first resolve each force into its respective scalar components. Do this using...
Transformation of Plane Strain
Under plane strain conditions, typical for members where one dimension significantly exceeds the others, deformations and resultant strains are...
Design Example: Analyzing Capacity Contours for Flood Risk Assessment
Depth Perception and Spatial Vision