Postural control in children and young adults with vergence insufficiency

Abstract

Purpose: To study the postural control in children and young adults with vergence insufficiency. Deficits of vergence anomalies and ocular instability or misalignment can influence postural control. Vergence deficits that deteriorate gaze stabilization during body displacement had been described to cause blurry vision and vertigo.

Methods: A posturography system (Dynaport) was used to examine posture in quiet stance. The child was asked to fixate a target at 40 cm or at 200 cm, either with eyes open (vision condition) or with eyes covered by a monocular (monocular vision condition) or a binocular cover (no vision condition) . During 30 sec data were recorded by Mira 2 software. Eighteen children and young adults (range 6 to 35 year-old) were selected and tested, 8 presenting vergence insufficiency and 10 normal subjects. The patients had complete ocular and orthoptic evaluation examination initially and repeated at 3 months after treatment including orthoptic reeducation.

Results: Ocular examination assessed the vergence insufficiency of the 8 subjects and hyperopia was present in 7 of them. Before treatment, amplitude of postural movements in subjects with vergence insufficiency was significantly larger than in normal subjects. Of the 8 subjects with vergence insufficiency, 6 presented a significant data improvement of amplitude of postural movements. Data with different binocular, monocular and no vision conditions are detailed and analysed.

Conclusions: Binocular visual information, such as vergence disparity, is essential in stabilizing posture at far and near distance. Postural instability reported in children with vergence abnormalities could be due to poor vergence inputs and/or to immature compensatory mechanisms controlling postural stability as vestibular, somatosensory inputs and/or cerebellar processes. This simple technique can be useful to explore and evaluate abnormal binocular conditions before and after treatment. Further studies are needed to evaluate binocular pathologies including vergence anomalies and strabismus.

Keywords: 522 eye movements • 524 eye movements: recording techniques • 525 eye movements: saccades and pursuits