In the literature, Fox 30 tested the postural stability during binocular and monocular viewing at far distance cm and did not find any difference between the two viewing conditions. On the other hand, Isotalo et al. During binocular viewing, they observed a deterioration of stability at far distance. In other words, children benefit from binocular vision at near and show no penalty from the absence of binocular vision at far distance; in contrast, adults show no significant benefit at near and a penalty at far distance.
We have no explanation for this difference between children and adults. Binocular vision seems to be used more by children than by adults.
The superiority of binocular versus monocular visual inputs is well known see the introduction , but the novelty is that binocular visual inputs allow a better postural stability at near distance only. We suggest that improvement of posture at near could be due to improved perception of movement in depth, based on changes in binocular disparity; such changes could result from anteroposterior body oscillation and could be used to stabilize the body.
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At near distance, the angular size of the target monocular or binocular viewing is higher, allowing better postural stabilization. Thus, in the presence of multiple perceived visual signals, including better control of oculomotor vergence, children optimize their postural stability at near distance when both eyes are viewing. Finally, during monocular viewing, one could expect similar postural control for both groups of children given the absence of binocular disparity vergence inputs.
However, this was not the case, and any interaction between group and viewing condition was not reported. Most likely, during monocular viewing, even if disparity vergence inputs are eliminated, monocularly driven vergence inputs e.
We suggest that such inputs are impaired in children with vertigo. Thus, poor postural control in children with vertigo is not only due to abnormalities of binocular disparity vergence but also to monocular vergence inputs. In this study, postural control was impaired in children with vertigo compared with that in normal children.
Our sample had normal vestibular function but vergence abnormalities Table 2. Consequently, based on these clinical measures, we suggest that the postural instability reported herein was not due to reduced vestibular signals but most likely to impaired vergence inputs. The oculomotor deficits clinically assessed in these children with vertigo could deteriorate the quality of visual inputs—for example, reducing the quality of oculomotor vergence signals leading to poor internal proprioceptive feedback mechanism, resulting in poor postural control.
Even if proprioception is recognized as the main source of sensory information for balance control on a static surface, 33 34 recent studies from our group in normal adults 7 suggest that oculomotor vergence signals, including oculomotor proprioception, may play an important role in static postural control.
Our results show that this occurs also in children and support the hypothesis that correct vergence information is necessary for good control of posture. Another hypothesis has been proposed by Friedrich et al. They showed that when visual inputs are deficient, compensation mechanisms, vestibular somatosensory inputs, and cerebellar processes can be activated to assure good postural control.
In children and in adolescents with vertigo and vergence abnormalities such compensatory mechanisms may be immature leading to poor postural control. This idea agrees with the hypothesis made by several investigators in developmental studies on dynamic balance control. Such capacity probably is essential for both dynamic and static postural control mechanisms and develops with age. Submitted for publication February 9, ; revised March 31 and April 16, ; accepted July 16, Disclosure: M.
Bucci , None; T. Wiener-Vacher , None; D. Bouet , None; Z. Kapoula , None. The publication costs of this article were defrayed in part by page charge payment. T able 1. View Table. Characteristics of Children with No Vertigo Symptoms. T able 2. Characteristics of Children with Vertigo and Vergence Abnormalities. F igure 1. View Original Download Slide. Mean and SD of the standard deviation of lateral and anteroposterior body sway and of surface and variance of speed of COP for far cm and near 40 cm fixation for the two groups of children in the two conditions tested vision versus no vision.
F igure 2.
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Data are shown for 19 normal children and 15 children with vertigo. The authors thank the children who participated in the study. Vertigo: Its Multisensory Syndromes. Springer Berlin. Vertigo is an underestimated symptom of ocular disorders: dizzy children do not always need MRI. Pediatr Neurol. Abnormality of vergence latency in children with vertigo.
J Neurol. Speed-accuracy of saccades, vergence and combined movements in children with vertigo. Exp Brain Res. Binocular coordination of saccades in children with vertigo: dependency on the vergence state.
Vision Res. The Neurology of Eye Movement. Effects of distance and gaze position on postural stability in young and old subjects. Influence of motion parallax in the control of spontaneous body sway.
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The visual and driving performance of monocular and binocular heavy-duty truck drivers. Accident Anal Prevent. Distance estimation in the visual and visuomotor systems. MagneP, CoelloY. Retinal and extra-retinal contribution to position coding. Behav Brain Res. Binocular vision and prehension in middle childhood. Distance impairs postural stability only under binocular viewing. Canal and otolith vestibulo-ocular reflexes to vertical and off vertical rotations in children learning to walk. Acta Otolaryngol. Vestibular impairments pre- and post-cochlear implant in children. Int J Pediatr Otorhinolaryngol.
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Acta Ophthalmol Scand. Mosby St. KapoulaZ, BucciMP. Postural control in dyslexic and non-dyslexic children.
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Role of ocular convergence in the Romberg quotient. Gait Posture. JeanrotN, JeanrotF. Manuel de Strabologie. Frequency of convergence insufficiency in optometry clinic setting. Optom Vison Sci.