Back to Journals » Clinical Ophthalmology » Volume 12

Binocular coordination and reading performance during smartphone reading in intermittent exotropia

Authors Hirota M, Kanda H, Endo T, Morimoto T, Miyoshi T, Fujikado T

Received 21 June 2018

Accepted for publication 21 August 2018

Published 16 October 2018 Volume 2018:12 Pages 2069—2078


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Scott Fraser

Supplementary video 2 of representative movement recording while smartphone reading in a patient with X(T).

Views: 514

Masakazu Hirota,1 Hiroyuki Kanda,1 Takao Endo,2 Takeshi Morimoto,1 Tomomitsu Miyoshi,3 Takashi Fujikado1

1Department of Applied Visual Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; 2Department of Ophthalmology, Osaka University Graduate School of Medicine, Izumi, Osaka, Japan; 3Department of Integrative Physiology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan

Purpose: This study aimed to evaluate binocular coordination using video-oculography during smartphone reading in patients with intermittent exotropia compared to individuals with normal vision.
Patients and methods: Eleven youth and adult patients with intermittent exotropia (21.9±9.3 years) and 15 control subjects (26.6±4.3 years) were examined. Eye movements were recorded during smartphone reading at 50, 30, and 20 cm using video-oculography. The loss of binocular coordination was tentatively defined as a horizontal disparity greater than 2°. The proportion of monocular viewing was the percentage of time for which binocularity was lost during smartphone reading. The proportion of monocular viewing, the reading speed, and the correlation between proportion of monocular viewing and reading speed were analyzed.
Results: The proportion of monocular viewing during smartphone reading was significantly higher in the intermittent exotropia group than in the control group (P<0.001). It was significantly more frequent at 20 cm than at 50 cm in the intermittent exotropia group (P<0.05). The reading speed was significantly negatively correlated with the proportion of monocular viewing at 30 and 20 cm in the intermittent exotropia group (P<0.05).
Conclusion: A significant increase in the proportion of monocular viewing in the intermittent exotropia group suggests that an appropriate viewing distance should be advised so that users can maintain binocular coordination when viewing a smartphone.

Keywords: eye movement, smartphone reading, video-oculography, intermittent exotropia

Creative Commons License This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.

Download Article [PDF]  View Full Text [HTML][Machine readable]