Dynamic Fusional Vergence Eye Movements in Congenital Esotropia

Yair Morad*, 1, Horace Lee2, Carol Westall1, Stephen P Kraft1, Carole Panton1, Ruth Sapir-Pichhadze2, Moshe Eizenman2
1 Department of Ophthalmology, The Hospital for Sick Children, and the University of Toronto, Toronto, Ontario, Canada
2 Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada

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2008 Bentham Science Publishers Ltd

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestrictive use, distribution, and reproduction in any medium, provided the original work is properly cited.

* Address correspondence to this author at the Pediatric Ophthalmology Service, Assaf Harofeh Medical Center, Zrifin 73000, Israel; Tel: 972-8-9779620; Fax: 972-8-9779361; E-mail:



To evaluate whether a selected group of 9 children with history of congenital esotropia is capable of producing vergence eye responses to fusional disparity stimuli.


Nine children with history of congenital esotropia and 5 age-matched children with normal binocular vision were examined. Using a full-field target, vergence responses to base out 3 prism diopters placed in front of both eyes were recorded.


In five patients, the initial response was a saccade generated by the dominant eye, followed by a disconjugate movement of one or both eyes. In two patients with long standing uncorrected strabismus, the responses were almost purely saccadic, while in two other patients, in whom early surgery resulted in fusional abilities, smooth vergence movements were recorded.


This study adds further evidence that patients with history of congenital esotropia patients are capable of producing vergence eye movements in response to fusional disparity. The responses usually start with a saccade followed by a vergence response. The preference for initial saccadic or vergence response is correlated with sensorial tests of stereopsis and motor fusion and may be related to the size of the suppression scotoma in the deviating eye, the duration of misalignment, or both.

Keywords: Strabismus, infantile esotropia, vergence, fusional disparity.