Dynamic fusional vergence eye movements in congenital esotropia

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.