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Reading: Do we really need binocular single vision?


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Original article

Do we really need binocular single vision?


Kathryn C. Brown ,

Orthoptic Department, Bradford Royal Infirmary, Duckworth Lane, Bradford BD9 6RJ, GB
About Kathryn C.

B Med Sci (Orthoptics)

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David Buckley

University of Sheffield, Academic Unit of Ophthalmology and Orthoptics, Royal Hallamshire Hospital, Sheffield, GB
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Aim: To investigate whether or not we need binocular single vision (BSV) for successful depth perception.

Methods: A mixed-measures design was used to compare monocular subjects and binocular subjects in their ability to judge depth. Experimental stimuli were images resembling large drawing pins that were displayed on a computer screen. Subjects had to adjust the spike of the drawing pin, by means of a keypad, until it appeared to be at an angle of 90° to the head of the pin. The head of the drawing pin was at a slant of 30° from the frontal plane, around either the horizontal or vertical axis. The computer recorded the number of degrees away from the 90° position that the spike was set, the time taken and the standard deviation of the settings. A three-factor mixed measures ANOVA was used to analyse the results.

Results: Overall, binocular subjects were more accurate than monocular subjects (F = 13.894, df = 1, 14, p < 0.01) in judging when the spike was set at an angle of 90° to the head of the pin. There was no significant difference between the horizontal or vertical orientations of stimuli in terms of accuracy (F = 1.250, n.s.), or between the two groups in the time it took them to complete the task.

Conclusion: BSV is advantageous and the time and resources spent on restoring and maintaining BSV are worthwhile.

How to Cite: Brown, K.C. and Buckley, D., 2004. Do we really need binocular single vision?. British and Irish Orthoptic Journal, 1, pp.46–51. DOI:
Published on 01 Jan 2004.
Peer Reviewed


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