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Changes in cyclotorsion and vertical eye alignment during prolonged monocular occlusion

Graf, Erich W., Maxwell, James S. and Schor, Clifton M. (2002) Changes in cyclotorsion and vertical eye alignment during prolonged monocular occlusion Vision Research, 42, (9), pp. 1185-1194. (doi:10.1016/S0042-6989(02)00047-0).

Record type: Article


When binocular vision is prevented with monocular occlusion, the two eyes assume a position of rest related to the combination of underlying tonic innervation of the oculomotor system, cross-coupled accommodative-vergence input and vergence responses to perceptual cues for spatial location relative to the head. When the latter two are controlled, the covered eye has been shown in the majority of subjects to turn outward (exophoria) and upward (hyperphoria) after prolonged monocular occlusion. The present study investigates the change in torsional eye alignment and its relation to vertical eye alignment after eight hours of monocular occlusion. The results revealed an excyclophoria during occlusion in four out of five subjects. The patched eye also became elevated in two subjects and depressed in two others. Thus, during prolonged monocular occlusion, the relative directions of cyclophoria and vertical phoria appear to be independent. In addition, there were non-concomitant changes in vertical phoria with horizontal gaze, toward a state where the adducted eye was elevated relative to the abducted eye. Simulations with Orbit(TM) suggest that these non-concomitant changes in vertical phoria with a concomitant excyclophoria may be based upon orbital mechanics. Excyclophoria appears to be the baseline state of binocular alignment.

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Published date: April 2002
Keywords: phoria, occlusion, tonic vergence


Local EPrints ID: 47989
ISSN: 0042-6989
PURE UUID: 22aedd52-22bd-484b-80ef-dc338ac1c1b9
ORCID for Erich W. Graf: ORCID iD

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Date deposited: 16 Aug 2007
Last modified: 17 Jul 2017 15:01

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Author: Erich W. Graf ORCID iD
Author: James S. Maxwell
Author: Clifton M. Schor

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