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Is there a relationship between prism fusion range and vergence facility?

Melville, A.C. and Firth, A.Y. (2002) Is there a relationship between prism fusion range and vergence facility? British Orthoptic Journal, 59. pp. 38-44. ISSN 0068-2314


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Aim: To investigate the relationship between prism fusion range (PFR) and vergence facility (VF) measurements in subjects with normal binocular vision.

Methods: Twenty-eight subjects (mean age 19 ± 1 years) with normal binocular single vision (BSV) underwent measurement of the PFR and VF in a varied order, at a test distance of 1/3 m. The PFR measurements recorded were the base out (BO) range to blur and break point and base in (BI) range to break point. The total PFR was calculated. The VF was assessed over a 1 min time period using a 12(Δ)BO/ 3(Δ)BI flip prism and recorded in cycles per minute (cpm).

Results: No correlation was demonstrable between any of the single measures of the PFR and the VF results. The BO PFR to break point and the BI PFR results obtained (means 46(Δ) BO and 14(Δ) BI) were not significantly different from quoted ‘normal’ values. The VF results obtained (mean 12 ± 4.2 cpm) were found to be significantly different from the reported mean value.

Conclusion: In a group of young adults with normal BSV, no correlation between PFR and VF was found. The two tests may quantify different aspects of vergence or, alternatively, results of one or both tests in this study may be unreliable.

Item Type: Article
Copyright, Publisher and Additional Information: Copyright © 2002 British Orthoptic Journal
Keywords: prism fusion range, fusional amplitudes, fusional vergences, vergence facility
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Medicine, Dentistry and Health (Sheffield) > School of Medicine (Sheffield) > Clinical Sciences Division South (Sheffield)
Depositing User: Sherpa Assistant
Date Deposited: 26 Aug 2005
Last Modified: 05 Jun 2014 16:30
Status: Published
Refereed: Yes
URI: http://eprints.whiterose.ac.uk/id/eprint/625

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