Vergence and Standing Balance in Subjects with Idiopathic Bilateral Loss of Vestibular Function

Neuro-ophthalmic and Neuro-otologic Evaluation in Individuals with Motion Sickness Susceptibility

Since the physiological background of motion sickness is not entirely clear, it was aimed to examine the physiological differences in groups consisting of individuals susceptible and non-susceptible to motion sickness. Sixty subjects [motion sickness (MS) group: 33 female, 3 male; 28.8 ± 8.1 years; control group: 19 female, 5 male; 24.5 ± 4.3 years] were included in the study. Near visual acuity test on the treadmill in the presence of visual stimulation, pattern visual-evoked potentials, oculomotor tests, and computerized dynamic posturography were applied. Receiver operating characteristic analysis was performed to determine the parameter that provides the excellent discrimination between the groups. The most effective parameter in differentiating the study groups was determined as dynamic visual acuity with 77.8% sensitivity and 95.8% specificity. Significant differences were found in the vestibular (mean ± standard deviation: 0.63 ± 0.17), visual (0.77 ± 0.18), and composite scores (73.11 ± 11.89) of the patients (P=.000) in posturographic evaluation. In the visual-evoked potential examination, a significant decrease was found in the amplitude values between the P100-N145 waves in the binocular (5.0 ± 2.8, P=.002), right eye (7.6 ± 3.2, P=.009) and left eye (7.9 ± 2.9, P=.016) in the symptomatic patients. In binocular oculomotor evaluation, directional asymmetric findings were obtained. It has been shown that the most effective test parameter that distinguishes the MS susceptible and non-susceptible individuals is the dynamic visual acuity value. Based on the results of neuro-physiological tests, it was suggested that a possible visual-vestibular integration disorder in individuals susceptible to motion sickness may affect visual and vestibular performance.

Vestibular asthenopia

Vestibular asthenopia, analogous to visual asthenopia, is a sensory (or sensory-motor) discomfort consisting of a set of subjective symptoms, the expression of which is essentially visual and whose origin is a transient vestibular incident. It can be considered the result of a sudden global central disorder, such as a "computer glitch," following a chain of events in response to an initial vestibular disease, even minor and devoid of clinical signs. This disorder results in inadequate processing and imperfect integration of afferent visual and vestibular input, leading to ocular fatigue, pain associated with eye movement, and sensitivity to retinal slip.

Osteopathic manipulative treatment in individuals with vertigo and somatic dysfunction: a randomized, controlled, comparative feasibility study

Context

There is a paucity of research assessing the efficacy of osteopathic manipulative treatment (OMT) in patients with vertigo.

Objective

To assess the feasibility of conducting a randomized, controlled trial comparing OMT and vestibular rehabilitation therapy (VRT), alone or in combination, in patients with vertigo and somatic dysfunction.

Methods

Volunteers with vertigo who were also diagnosed with somatic dysfunction (SD) were prospectively enrolled in a blinded, randomized, controlled cohort comparative effectiveness study and assigned to 1 of 4 groups: OMT alone, VRT alone, a combination of OMT and VRT (OMT/VRT), or a nonintervention control group. Participants between 18 and 79 years of age were included if they had experienced symptoms of vertigo for at least 3 months' duration, demonstrated somatic dysfunction, and could participate in computerized dynamic posturography (CDP) testing, tolerate manual therapy and exercises, and communicate effectively in English or Spanish. A total of 3 treatments lasting 45 minutes each were administered 1 week apart to each participant. OMT in this study consisted of counterstrain, myofascial release, balanced ligamentous tension, soft tissue, HVLA, and articulatory techniques. Comparisons were made between composite scores (CS) assessed with computerized dynamic posturography (CDP), dizziness handicap inventory (DHI), optometric evaluation, and osteopathic structural examinations collected before the first treatment, after the third/final treatment, and 3 months after the final treatment. (ClinicalTrials.gov number NCT01529151).

Results

A total of 23 patients were included in the study: 7 in the OMT group, 5 in the VRT group, 6 in the OMT/VRT group, and 5 in the control group. The OMT/VRT group demonstrated significant improvement in DHI score (P=0.0284) and CS (P=0.0475) between pre- and 3-month posttreatment measures. For total severity, improvements were significant in the OMT group both from pretreatment to immediate posttreatment measures (P=0.0114) and from pretreatment to 3-month posttreatment measures (P=0.0233). There was a statistical difference between the OMT and control groups from pretreatment to 3-month posttreatment DHI scores (P=0.0332). Also, there was a statistical difference in DHI score between VRT and control from pre- to 3-month posttreatment scores (P=0.0338). OMT/VRT statistically and clinically improved visual acuity in patients' right eyes from pre- to posttreatment (P=0.0325). In all participants, vergence dysfunction was prevalent (5; 21.7%) in addition to vertical heterophoria (15; 65.2%).

Conclusion

A combination of OMT and VRT significantly reduced vertigo and improved balance 3 months after treatment (P<0.05). There was a high prevalence in vergence and vertical heterophoria, which are not typical screening measurements used by physical therapists and physicians to assess vertigo patients. With a small sample size, this study demonstrated the feasibility of an interdisciplinary team evaluating and treating patients with vertigo in a community setting. A larger study is needed to assess the efficacy of OMT/VRT in vertigo patients.

A Systematic Review on Balance Performance in Patients With Bilateral Vestibulopathy

OBJECTIVE

Patients with bilateral vestibulopathy (BVP) have severe balance deficits, but it is unclear which balance measures are best suited to quantify their deficits and approximate the diversity of their self-reports. The purpose of this study was to explore measures of balance control for quantifying the performance of patients with BVP related to different balance domains, allowing targeted assessment of response to intervention.

METHODS

MEDLINE, Web of Science, and Embase were systematically searched on October 9, 2019. The Scottish Intercollegiate Guidelines Network checklist for case-control studies was applied to assess each individual study's risk of bias. Standardized mean differences (SMD) were calculated based on the extracted numeric data and reported according to the type of sensory perturbation in the balance tasks.

RESULTS

Twelve studies (1.3%) met the eligibility criteria and were analyzed, including data of 176 patients with BVP, 196 patients with unilateral vestibulopathy, and 205 healthy controls between 18 and 92 years old. In general, patients with BVP were either unable to maintain (or had reduced) balance during tasks with multisensory perturbations compared with healthy controls (range of mean SMD = 1.52-6.92) and patients with unilateral vestibulopathy (range of absolute mean SMD = 0.86-1.66).

CONCLUSIONS

During clinical assessment to quantify balance control in patients with BVP, tasks involving multisensory perturbations should be implemented in the test protocol.

IMPACT

As patients with BVP show difficulties with movement strategies, control of dynamics, orientation in space, and cognitive processing, clinicians should implement these aspects of balance control in their assessment protocol to fully comprehend the balance deficits in these patients.

Visual Binocular Disorders and Their Relationship with Baropodometric Parameters: A Cross-Association Study

The aim of this study was to establish a relationship between nonstrabismic binocular dysfunction and baropodometric parameters. A total of 106 participants underwent binocular vision assessment by evaluating horizontal heterophoria, horizontal and vertical fusional vergence ranges, and vergence facility. Posturography was measured using the FreeMED baropodometric platform. Among the variables that the software calculates are foot surface, foot load, and foot pressure. Our results showed that in the participants with positive fusional vergence (PFV) (near) blur and recovery values outside the norm, there are statistically significant differences between the total foot area (p < 0.05), forefoot area (p < 0.05), forefoot load (p < 0.05), and rearfoot load (p < 0.05), in all of the cases of left foot vs. right foot. In the group of subjects who did not meet Sheard's criterion (distance), that is, those with unstable binocular vision, there was a statistically significant difference (p < 0.01) between maximum left and right foot pressure. In conclusion, our results establish a relationship between nonstrabismic binocular dysfunctions and some baropodometric parameters.

Long term follow up after transorbital penetrating injury: A case report

Purpose

Traumatic brain injury is the leading cause of mortality and disability among young individuals. Unfortunately, there are few publications concerning long term follow up of patients with these types of injuries. We present a case of trans-orbital penetrating brain injury with an 18 year follow up.

Observations

A 43-year-old, previously healthy, male was accidently impaled on a fencing foil resulting in a penetrating brain injury. Initial symptoms included diplopia, ophthalmoparesis, a non-reactive pupil, decreased visual acuity, decreased sensation across the cheek, dysphagia and dysarthria. CT scan taken on presentation showed a clear tract of the foil traversing the various structures of the brain. One week after the trauma, the patient developed a unique constellation of paroxysmal attacks of autonomic dysfunction consisting of profuse diaphoresis and decreased skin temperature on the left side of the body, as well as dilation of the left pupil. Three months after the accident, the patient suddenly experienced severe constant pain affecting the left side of his body associated with thermal and tactile allodynia. On latest follow up, 18 years after the accident, the patient continues to have chronic pain, allodynia, and lack of temperature sensation throughout the left face, arm, and leg. He has a wide based, hemi-ataxic gait, with the left leg swinging out and around. EMG and nerve conduction studies have found no voluntary activity in the temporalis and masseter muscles resulting in atrophy and fibrosis. An MRI shows linear encephalomalacia along the path of the foil extending to the pons, involving the right spinothalamic tract, and cerebellum.

Conclusions and Importance

Our case illustrates the importance of such a longitudinal follow up. It demonstrates the possible severity of the sequelae from these types of injuries including chronic pain and gait ataxia, as well as EOM and autonomic dysfunction. Due to the potential ongoing needs of such patients, it is important to plan a long-term, team-based approach that centers around physical therapy and improving long term quality of life.

Fifteen Years of Wireless Sensors for Balance Assessment in Neurological Disorders

Balance impairment is a major mechanism behind falling along with environmental hazards. Under physiological conditions, ageing leads to a progressive decline in balance control per se. Moreover, various neurological disorders further increase the risk of falls by deteriorating specific nervous system functions contributing to balance. Over the last 15 years, significant advancements in technology have provided wearable solutions for balance evaluation and the management of postural instability in patients with neurological disorders. This narrative review aims to address the topic of balance and wireless sensors in several neurological disorders, including Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, stroke, and other neurodegenerative and acute clinical syndromes. The review discusses the physiological and pathophysiological bases of balance in neurological disorders as well as the traditional and innovative instruments currently available for balance assessment. The technical and clinical perspectives of wearable technologies, as well as current challenges in the field of teleneurology, are also examined.

Recent advances in idiopathic bilateral vestibulopathy: a literature review

Background

Idiopathic bilateral vestibulopathy (IBV) is an acquired bilateral peripheral vestibular dysfunction of unknown etiology, with persistent unsteadiness but without sensorineural hearing loss (SNHL) other than age-related hearing loss (ARHL).

Main text

The prevalence of IBV is unknown. The most common symptom is persistent unsteadiness, particularly in darkness and/or on uneven ground. The other main symptom is oscillopsia during head and body movements. IBV is neither associated with SNHL, except for ARHL, nor any other neurological dysfunction that causes balance disorders. The clinical time course of IBV can generally be divided into two main types: progressive type and sequential type. The progressive type involves gradually progressive persistent unsteadiness without episodes of vertigo. The sequential type involves recurrent vertigo attacks accompanied by persistent unsteadiness. Originally, IBV was found to exhibit bilateral dysfunction in the lateral semicircular canals (LSCCs) and the superior vestibular nerve (SVN) system. However, recently, with the development of more sophisticated vestibular function tests of the otolith organs and vertical semicircular canals, it has been revealed that IBV involves peripheral vestibular lesions other than those already identified in the LSCC and the SVN system. Furthermore, novel subtypes of IBV that do not involve bilateral dysfunction of the LSCC and/or the SVN system have been proposed. Therapeutically, exercise-based vestibular rehabilitation in adult bilateral vestibulopathy (BVP) patients has resulted in improved gaze and postural stability moderately. There are several technical approaches for the treatment of BVP such as vestibular implants, sensory substitution devices and noisy galvanic vestibular stimulation.

Conclusions

Combined use of various vestibular function tests, including recently developed tests, revealed the diversity of lesion sites in IBV. Further studies are required to determine the therapeutic effects of the technical approaches on IBV.

Relation between cognitive and cerebello-thalamo-cortical functions in healthy elderly people: Evidence from the Yakumo Study

Relations between cognitive and cerebello-thalamo-cortical functions in healthy elderly people (65-75 years old) were examined by longitudinal behavioral data. Based on the individually calculated cognitive decline ratio in D-CAT (digit cancelation test) and in LMT (Logical Memory Test) during the period of 11 years, participants were classified into the Decline and the Maintain groups and group differences in the postural tremor measures (Quotient of Romberg) were compared. Significant group differences were shown in the postural tremor measure in D-CAT that reflects prefrontal function, but it was not the case in LMT. These results strengthened our previous findings that suggest a strong relation between the cerebello-thalamo-cortical function and the prefrontal cortex function using behavioral measures. Findings provide evidence that to strengthen postural function such as physical exercise is effective for slowing cognitive decline with age.

Postural Patterns of the Subjects with Vergence Disorders: Impact of Orthoptic Re-education, a Pilot Study

Aim:

Vergence insufficiency is a common oculomotor disorder which causes visual but also general, and even postural symptoms. This study aimed to characterise postural control of subjects with isolated vergence disorder and assess whether orthoptic therapy affects it.

Method:

Vergence disorders were evaluated and treated by orthoptists. Postural control quality was measured before and after orthoptic therapy in different conditions to study the role of vision, fixating distance, binocular vision and ocular dominance.

Results:

Before orthoptic therapy, we recorded less body sway when subjects had their eyes closed than when they had their eyes open, and also less sway for the binocular condition when compared with monocular viewing conditions. This is opposite to well-known normal behaviour. Moreover, no distance or ocular dominance effect was found. After orthoptic therapy, our subject’s body sway was less when they had their eyes open than with their eyes closed and less when they looked at near fixation. No difference was found between monocular and binocular viewing conditions, but a small advantage of ocular dominance was found for one parameter.

Conclusion:

We conclude that subjects with vergence disorders show postural behaviour that is not characterized by the normal regularities observed in healthy subjects. Orthoptic re-education may have contributed to promoting such regularities. Further studies are needed to confirm these preliminary results.

Full Spectrum of Reported Symptoms of Bilateral Vestibulopathy Needs Further Investigation-A Systematic Review

Objective

To systematically review the symptoms reported by patients with bilateral vestibulopathy (BV) in clinical studies and case reports. This would serve as the first step in establishing a validated patient-reported outcome measures (PROM) for BV.

Methods

A search on symptoms reported by patients with BV was performed in PubMed, and all publications covering these symptoms were included. Exclusion criteria comprised reviews and insufficient details about the frequency of occurrence of symptoms.

Results

1,442 articles were retrieved. 88 studies were included (41 clinical studies, 47 case reports). In consensus, 68 descriptions of symptoms were classified into 6 common and generic symptoms. Frequency of symptoms in clinical studies and case reports were reviewed, respectively; imbalance (91 and 86%), chronic dizziness (58 and 62%), oscillopsia (50 and 70%), and recurrent vertigo (33 and 67%). BV could be accompanied by hearing loss (33 and 43%) and tinnitus (15 and 36%). 15 clinical studies and 10 case reports reported symptoms beyond vestibular and hearing deficits such as limited social activities, depression, concentration, and memory impairment and reduced quality of life in general.

Conclusion

The literature on BV symptomatology mainly focuses on classic symptoms such as imbalance and oscillopsia, while only few report additional symptoms such as cognitive memory impairment and performing dual tasks. In fact, none of the reviewed clinical studies and case reports provided a comprehensive overview of BV symptoms. To develop a validated PROM, qualitative research using semi-structured and unstructured interviews is needed to explore the full spectrum of BV symptoms.

Reeducation of vergence dynamics improves postural control

INTRODUCTION

The purpose was to investigate the effect of vergence reeducation on postural control, in subjects with isolated vergence disorders.

MATERIAL AND METHODS

We studied the dynamics of vergence in 19 subjects (20-44 years old) using video-oculography (Eye See Cam). On the basis of orthoptic and symptomatology assessments, ten of the subjects were diagnosed for vergence disorders then vergence eye movements were reeducated with the REMOBI method (US8851669, 5 weekly sessions lasting for 35min). Postural control was measured before and after reeducation, postural recording was done in upright stance (Dynaport), with both eyes closed or open and looking a visual target located at 2m distance.

RESULTS

After reeducation with REMOBI, the visual symptomatology faded away and the stereoacuity improved at least for some subjects; the vergence latency decreased significantly and the vergence accuracy increased significantly. In terms of posture, the Mean Power Frequency (MPF) of the body sway decreased significantly in both eyes open and eyes closed conditions. Considering all subjects together (i.e. healthy subjects and subjects with vergence disorders before the reeducation), the antero-posterior body sway (Root Mean Square A/P) was positively correlated with the visual symptomatology: the higher the visual symptomatology, the higher was the body sway.

CONCLUSION

The results bring evidence for synergy between the quality of vergence and the quality of postural control. They open a new research line that bridges the gap between neuroscience, ophthalmology-orthoptics and posturology.

Anchoring the Self to the Body in Bilateral Vestibular Failure

Recent findings suggest that vestibular information plays a significant role in anchoring the self to the body. Out-of-body experiences of neurological origin are frequently associated with vestibular sensations, and galvanic vestibular stimulation in healthy participants anchors the self to the body. Here, we provide the first objective measures of anchoring the self to the body in chronic bilateral vestibular failure (BVF). We compared 23 patients with idiopathic BVF to 23 healthy participants in a series of experiments addressing several aspects of visuo-spatial perspective taking and embodiment. In Experiment 1, participants were involved in a virtual "dot-counting task" from their own perspective or the perspective of a distant avatar, to measure implicit and explicit perspective taking, respectively. In both groups, response times increased similarly when the avatar's and participant's viewpoint differed, for both implicit and explicit perspective taking. In Experiment 2, participants named ambiguous letters (such as "b" or "q") traced on their forehead that could be perceived from an internal or external perspective. The frequency of perceiving ambiguous letters from an internal perspective was similar in both groups. In Experiment 3, participants completed a questionnaire measuring the experienced self/body and self/environment "closeness". Both groups reported a similar embodied experience. Altogether, our data show that idiopathic BVF does not change implicit and explicit perspective taking nor subjective anchoring of the self to the body. Our negative findings offer insight into the multisensory mechanisms of embodiment. Only acute peripheral vestibular disorders and neurological disorders in vestibular brain areas (characterized by strong multisensory conflicts) may evoke disembodied experiences.

Active ocular vergence improves postural control in elderly as close viewing distance with or without a single cognitive task

Performance of the vestibular, visual, and somatosensory systems decreases with age, reducing the capacity of postural control, and increasing the risk of falling. The purpose of this study is to measure the effects of vision, active vergence eye movements, viewing distance/vergence angle and a simple cognitive task on postural control during an upright stance, in completely autonomous elderly individuals. Participated in the study, 23 elderly subjects (73.4 ± 6.8 years) who were enrolled in a center dedicated to the prevention of falling. Their body oscillations were measured with the DynaPort(®) device, with three accelerometers, placed at the lumbosacral level, near the center of mass. The conditions were the following: eyes open fixating on LED at 20 cm or 150 cm (vergence angle 17.0° and 2.3° respectively) with or without additional cognitive tasks (counting down from one hundred), performing active vergence by alternating the fixation between the far and the near LED (convergence and divergence), eyes closed after having fixated the far LED. The results showed that the postural stability significantly decreased when fixating on the LED at a far distance (weak convergence angle) with or without cognitive tasks; active convergence-divergence between the LEDs improved the postural stability while eye closure decreased it. The privilege of proximity (with increased convergence at near), previously established with foot posturography, is shown here to be valid for accelerometry with the center of mass in elderly. Another major result is the beneficial contribution of active vergence eye movements to better postural stability. The results bring new perspectives for the role of eye movement training to preserve postural control and autonomy in elderly.

Controlling Posture and Vergence Eye Movements in Quiet Stance: Effects of Thin Plantar Inserts

The purpose of this study was to assess properties of vergence and saccade eye movements as well as posture in quiet stance, and the effects of thin plantar inserts upon postural and oculomotor control. The performances of 36 young healthy subjects were recorded by a force platform and an eye tracker in three testing conditions: without plantar stimulation, with a 3 millimetre-thick plantar insert, either a Medial or a Lateral Arch Support (MAS/LAS). The results showed a decrease of the Surface and Variance of Speed and a more posterior position of the CoP with either stimulation compared with the control condition. The fractal analysis showed a decrease with MAS. Wavelet analysis in the time-frequency domain revealed an increase in the Cancelling Time of the low frequency band with MAS. These results suggest a better stability for a lower energy cost. Concerning eye movements, the inserts influenced only vergence (not saccades): MAS caused an increase of the phasic amplitude of divergence, and conversely a decrease of the tonic amplitude. In contrast, LAS caused an increase of the tonic amplitude of convergence. Thus, MAS renders divergence less visually driven, while LAS renders convergence more visually driven. We conclude that the CNS uses the podal signal for both postural and vergence control via specific mechanisms. Plantar inserts have an influence upon posture and vergence movements in a different way according to the part of the foot sole being stimulated. These results can be useful to clinicians interested in foot or eye.

Visiting Richard Serra's "Promenade" sculpture improves postural control and judgment of subjective visual vertical

Body sway while maintaining an upright quiet stance reflects an active process of balance based on the integration of visual, vestibular, somatosensory, and proprioceptive inputs. Richard Serra’s Promenade sculpture featured in the 2008 Monumenta exhibition at the Grand Palais in Paris, France is herein hypothesized to have stimulated the body’s vertical and longitudinal axes as it showcased five monumental rectangular solids pitched at a 1.69^° angle. Using computerized dynamic posturography we measured the body sway of 23 visitors when fixating a cross, or when observing the artwork (fixating it or actively exploring it with eye movements) before and after walking around and alongside the sculpture (i.e., before and after a promenade). A first fixation at the sculpture increased medio-lateral stability (in terms of spectral power of body sway). Eye movement exploration in the depth of the sculpture increased antero-posterior stability [in terms of spectral power and canceling time (CT) of body sway] at the expense of medio-lateral stability (in terms of CT). Moreover, a medio-lateral instability associated with eye movement exploration before the promenade (in terms of body sway sensu stricto) was canceled after the promenade. Finally, the overall medio-lateral stability (in terms of spectral power) increased after the promenade. Fourteen additional visitors were asked to stand in a dark room and adjust a luminous line to what they considered to be the earth-vertical axis. The promenade executed within the sculpted environment afforded by Serra’s monumental statuary works resulted in significantly improved performances on the subjective visual vertical test. We attribute these effects to the sculpted environment provided by the exhibition which may have acted as a kind of physiologic “training ground” thereby improving the visitors’ overall sense of visual perspective, equilibrium, and gravity.

Reliable assessment of physical activity in disease: an update on activity monitors

PURPOSE OF REVIEW

Physical activity is the main determinant of variability of individual energy expenditure. Reliable assessment of the activity level of an individual provides information on energy requirement and vital health. Here, evidence is presented on the validity of methods to assess physical activity as applied in health and disease.

RECENT FINDINGS

Improvement of technology has resulted in a growing number of physical activity monitors to evaluate the activity level of an individual. Outcome measures vary from raw data on body acceleration and posture to activity levels derived from proprietary algorithms based on body acceleration combined with sensor information on additional activity-induced physiological responses. Data interpretation is limited by evidence-based studies on the value of measured parameters for the assessment of physical activity.

SUMMARY

The optimal tool for reliable assessment of physical activity is an accelerometer providing a valid measure of body movement. Overall validity is derived from studies using doubly labelled water-assessed activity-induced energy as a reference. Thus, out of the large range of activity monitors, three came out with a better validity. The ultimate tool is a single unobtrusive device allowing valid and long-term monitoring of activity with regard to type and intensity.

Impaired body balance control in adults with strabismus

Previous studies revealed that people with binocular vision disorders have poor postural stability. However, most of the research was performed only on children and under binocular viewing condition, that could negatively affect the results. The aim of the current study was to investigate the influence of extra-ocular proprioceptive signals on postural stability in young adults with binocular vision disorders. Moreover, additional mental task was introduced to detect any postural compensation which could possibly hide the real influence of afferent extra-ocular signals. 21 Subjects, aged 18-45 yrs, with horizontal strabismus, were qualified to binocular vision disorders (BVD) group. 41 subjects, aged 19-45 yrs, with no strabismus formed the normal binocular vision (NBV) group. Posturography data were collected in 2 separate parts: (1) quiet standing (Single-Task), and (2) performance of a mental task while standing (Dual-Task). Each part consisted of three 60-s viewing conditions, with: (1) dominant/fellow eye (DE), (2) non-dominant/strabismic eye (NDE), and with (3) both eyes closed (EC). Subjects were looking at X located at the distance of 150 cm. Generally, BVD group showed elevated body balance during quiet stance compared to NBV group. Interestingly, better stabilization in BVD group occurred under NDE viewing. Surprisingly, additional mental task improved the postural stability in BVD group almost to the level of NBV group. These findings emphasize the role of the eye-muscle signals in postural control and suggest that suitable vision therapy can be the appropriate way to improve body balance/motor functions in people with binocular vision disorders.