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Front. Hum. Neurosci. | doi: 10.3389/fnhum.2019.00106

The binocular balance at high spatial frequencies as revealed by the binocular orientation combination task

Yonghua Wang1, 2,  Zhifen He2,  Yunjie Liang2,  Yiya Chen2, Ling Gong2,  Yu Mao2,  Xiaoxin Chen2, Zhimo Yao2,  Daniel Spiegel3, Jia Qu2, Fan Lu2,  Jiawei Zhou2* and  Robert F. Hess3
  • 1First Affiliated Hospital of Wenzhou Medical University, China
  • 2Wenzhou Medical University, China
  • 3McGill University, Canada

How to precisely quantify the binocular eye balance (i.e., the contribution that each eye makes to the binocular percept) across a range of spatial frequencies using a binocular combination task, is an important issue in both clinical and basic research. In this study, we aimed to compare the precision of a binocular orientation combination paradigm with that of the standard binocular phase combination paradigm in measuring the binocular eye balance at low to high spatial frequencies. Nine normal adults (average age: 24.6 ± 2.0 years old) participated. Subjects viewed an LED screen dichoptically with polarized glasses in a dark room. The method of constant stimuli was used to quantitatively assess the point of subjectively equality (PSE), i.e., the interocular contrast ratio when two eyes are balanced in binocular combination, for stimulus spatial frequencies from 0.5 to 8 cycles/degree. Precision was quantified by the variance (i.e., SE, obtained from 100 bootstrap estimates) associated to the PSE. Using stimuli whose interocular phase difference at the edge of the gratings were matched at 45°, we found that the orientation paradigm provides more precision than the standard binocular phase combination paradigm, especially at high frequencies (experiment 1). Such differences remained when using stimuli that had 3 times larger interocular phase difference (experiment 2) or displayed at 4 times higher stimuli resolution (experiment 3). Our results indicate that a binocular combination tasked based on orientation rather than phase, provides a more precise estimate of binocular eye balance in human adults at high spatial frequencies, thus allowing binocular balance to be assessed within the spatial region where amblyopes are most defective (i.e., high spatial frequencies).

Keywords: spatial frequency, binocular eye dominance, binocular orientation combination, binocular phase combination, contrast-gain

Received: 21 Dec 2018; Accepted: 11 Mar 2019.

Edited by:

Hidenao Fukuyama, Kyoto University, Japan

Reviewed by:

Jan Brascamp, Michigan State University, United States
Catherine Suttle, City University of London, United Kingdom  

Copyright: © 2019 Wang, He, Liang, Chen, Gong, Mao, Chen, Yao, Spiegel, Qu, Lu, Zhou and Hess. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Jiawei Zhou, Wenzhou Medical University, Wenzhou, 325035, Zhejiang Province, China, jiawei.zhou@mail.mcgill.ca