Romberg Quotient Research Articles

Is There a Relationship between Psychological Status and Posture in Chronic Low Back Pain?

Context: Chronic non-specific low back pain (CNLBP) is a major public health. Numerous studies have evaluated the contribution of post urology in the assessment and the rehabilitation of this pathology. Nevertheless, the relationship between post urology and muscle assessment is still a subject of controversy and no clear cause and effect relationship between the two could be established. Aim: The aim of our work was to investigate the relationship between post urological and muscular assessments in patients with CNLBP. Methods: It’s about an observational, descriptive, and cross-sectional study. The muscle assessment included Quadriceps Femoris flexibility using the heel-to-buttock distance and Hamstrings flexibility using the popliteal angle. Isometric muscle strength of the extensor and flexor muscles of the trunk was assessed by the Biering-Sorensen test and the Shirado test, respectively. The evaluation of static postural control was performed by the SATEL® force platform in two conditions (opened eyes/closed mouth) and (closed eyes/closed mouth). The selected parameters were S (mm2), XY (mm), X (mm), Y (mm), support (%), and Romberg Quotient (RQ). The chi-square test or Fisher's exact test was used to assess differences between categorical variables, and means were compared using Pearson's or Spearman's correlation tests depending on the distribution of the variables. Comparison between qualitative and quantitative variables was done by ANOVA test for normally distributed variables and Mann-Whitney or Kruskall-Wallis tests for non-normally distributed data. Results: Forty patients were included. The study of muscle flexibility according to force platform parameters showed that left Hamstring stiffness was significantly correlated with XY (p=.037) and with instability in the sagittal plane (p=.036). On the other hand, the stiffness of the anterior rectus muscles (right and/or left) was significantly correlated with XY (p=0.019 for the right muscle and 0.011 for the left muscle) and with postural instability in the frontal plane (p=.015 for the right muscle and .026 for the left muscle). We also founded a significant association between the increase in Romberg quotient and right Hamstring stiffness (p=.003). Conclusions: Our study as well as literature findings suggest that the Quadriceps Femoris and the Hamstrings play have a significant role in core stability of patients with chronic non-specific back pain. However, the origin of the population is also an important factor in the postural evaluation. A larger number of patients and a control group would have made it possible to establish a cause- effect relationship between Quadriceps Femoris, Hamstrings and static postural control abnormalities.

Sport dependent effects on the sensory control of balance during upright posture: a comparison between professional horseback riders, judokas and non-athletes.

Compared to judokas (JU) and non-athletes (NA), horseback riders (HR) may develop specific changes in their sensory control of balance. Thirty-four international-level JU, twenty-seven international-level HR and twenty-one NA participated. Participants stood upright on a plateform (static condition) or on a seesaw device with an instability along the mediolateral (ML) or the anteroposterior (AP) direction (dynamic conditions). These conditions were carried out with eyes opened (EO) or closed (EC), and with (wF) or without a foam (nF). Experimental variables included conventional (linear), non-linear center-of-pressure (COP) parameters, Romberg Quotient (RQ) and Plantar Quotient (PQ). Group effects. COP Surface (COPS) and standard deviation of COP along AP (SDY) were lower in HR than in JU in Static. SD Y was lower in HR than in JU in Dynamic AP. COP velocity (COPV) was lower in both HR and JU than in NA in Static and Dynamic. Sample entropy along AP and ML (SampEnY and SampEnX) were higher in HR than in JU in Static. SampEnY was higher in HR than in JU in Dynamic ML. Sensory effects. In EC, COPV was lower in JU than in NA in Dynamic AP, and lower in JU than in both HR and NA in Dynamic ML. In EO, COPV was lower in both JU and HR than in NA in Dynamic ML. RQ applied to COPS was lower in JU than in both HR and NA in Dynamic AP, and lower in JU than in HR in Dynamic ML. RQ applied to COPV was lower in JU than in both HR and NA in Static and Dynamic. PQ applied to COPS was higher in JU than in both HR and NA in Dynamic ML. Results showed that the effects of sport expertise on postural control could only be revealed with specific COP variables and were directionally oriented and sport-dependant. HR seem to rely more on vision than JU, thus revealing that the contribution of the sensory inputs to balance control is also sport-dependent. Results open up new knowledge on the specificity of sport practice on multisensory balance information during upright posture.

Individual-based predominance of visual input in multisensorial integration for balance is correlated with proprioceptive drift in rubber hand illusion.

Rubber hand illusion (RHI) is a traditional task that examines multisensory integration. The visual capture of tactile stimulus given to the seen rubber hand was considered to predominate the sensory processing and interfere with the bottom-up proprioceptive and tactile inputs received from the unseen real hand that results in mislocalization of participants hand towards rubber hand, namely proprioceptive drift (PD). Another task that requires multisensorial integration and shows a predominance of visual input is the maintenance of body posture. However, if the predominance of visual input in one task is generalizable to another task is yet to be elucidated. We aimed to examine if individual dependency on visual inputs in multisensorial integration in balance correlated with PD in RHI. Twenty healthy participants were recruited for the study and completed the RHI task. The contribution of visual inputs to the static body balance was measured with the instrumented clinical test of sensory interaction for balance and indexed with Romberg Quotient (RQ). We found a moderate positive correlation between PD and RQ. Individuals with more dependence on visual information in maintaining body posture had higher PD in RHI. Our results indicate that there can be an individual-based dependence on particular domains of sensory input preserved during different tasks of multisensorial integration. Future studies must clarify whether this tendency relates to certain physical or physiological traits.

Effects of compression garments on balance in hypermobile Ehlers-Danlos syndrome: a randomized controlled trial

Purpose To evaluate the immediate and 4-week effects of compression garments (CG) on balance using a force platform during 8 different visual, static, and dynamic conditions in hypermobile Ehlers-Danlos Syndrome (hEDS) patients. Methods Thirty-six participants were randomly assigned to a group: physiotherapy alone (PT, n = 19) or physiotherapy and daily CG wearing for 4 weeks (PT + CG, n = 17). Both attended 12 physiotherapy sessions (strengthening, proprioception, and balance exercises) for 4 weeks. Primary outcome: sway velocity of the centre of pressure (COP) measured before, immediately with the CG, and at 4 weeks. Secondary outcomes: ellipse area, Romberg quotient, and pain. Results Sway velocity in dynamic conditions decreased immediately with the CG. After 4 weeks of intervention, sway velocity (95% CI 4.36–39.23, effect size 0.93) and area (95% CI 146–3274, effect size 0.45) on the laterally oscillating platform with eyes-closed improved more in the PT + CG group than the PT group. Romberg quotient on foam cushion improved more in the PT + CG than the PT group. Pain decreased in both groups after 4 weeks with no between-group difference. Conclusion CG combined with physiotherapy improved dynamic balance measured with COP variables significantly more than physiotherapy alone in people with hEDS. Trial Registration NCT03359135

Incongruity of Geometric and Spectral Markers in the Assessment of Body Sway.

Different measurements of body oscillations in the time or frequency domain are being employed as markers of gait and balance abnormalities. This study investigates basic relationships within and between geometric and spectral measures in a population of young adult subjects. Twenty healthy subjects stood with parallel feet on a force platform with and without a foam pad. Adaptation effects to prolonged stance were assessed by comparing the first and last of a series of eight successive trials. Centre of Foot Pressure (CoP) excursions were recorded with Eyes Closed (EC) and Open (EO) for 90s. Geometric measures (Sway Area, Path Length), standard deviation (SD) of the excursions, and spectral measure (mean power Spectrum Level and Median Frequency), along the medio-lateral (ML) and antero-posterior (AP) direction were computed. Sway Area was more strongly associated than Path Length with CoP SD and, consequently, with mean Spectrum Level for both ML and AP, and both visual and surface conditions. The squared-SD directly specified the mean power Spectrum Level of CoP excursions (ML and AP) in all conditions. Median Frequency was hardly related to Spectrum Level. Adaptation had a confounding effect, whereby equal values of Sway Area, Path Length, and Spectrum Level corresponded to different Median Frequency values. Mean Spectrum Level and SDs of the time series of CoP ML and AP excursions convey the same meaning and bear an acceptable correspondence with Sway Area values. Shifts in Median Frequency values represent important indications of neuromuscular control of stance and of the effects of vision, support conditions, and adaptation. The Romberg Quotient EC/EO for a given variable is contingent on the compliance of the base of support and adaptation, and different between Sway Area and Path Length, but similar between Sway Area and Spectrum Level (AP and ML). These measures must be taken with caution in clinical studies, and considered together in order to get a reliable indication of overall body sway, of modifications by sensory and standing condition, and of changes with ageing, medical conditions and rehabilitation treatment. However, distinct measures shed light on the discrete mechanisms and complex processes underpinning the maintenance of stance.

Clinical evaluation of the Romberg quotient in stabilometry

Clinical evaluation of the Romberg quotient in stabilometry

Relative importance of vision and proprioception in maintaining standing balance in people with multiple sclerosis

BackgroundBalance impairment is common and a risk factor of falls in people with multiple sclerosis (MS). The purpose of this study was to evaluate the relative importance between vision and proprioception in maintaining standing body balance among individuals with MS compared with healthy individuals. MethodsThirty people with MS (the mean ± standard deviation of the Patient Determined Disability Steps: 3.62 ± 1.67 out of 8) and 25 healthy adults participated in this cross-sectional study. They underwent a static posturography test, consisting of three sensory feedback conditions: eyes open on a firm surface, eyes closed on a firm surface, and eyes open on a compliant surface. Their standing balance performance, quantified by the 95% confidence ellipse area and the total length of the center of pressure trajectory during each sensory condition, was calculated based on the ground reaction force data. The Romberg's quotient (the ratio of the center of pressure measurements on the firm surface between eyes open and eyes closed conditions) and proprioception quotient (the ratio of the center of pressure measurements with eyes open between firm and compliant standing surfaces) were calculated and compared between groups. ResultsPersons with MS demonstrated significantly larger postural sway under all three sensory conditions than their healthy counterparts. The reliance on the vision and proprioception systems in maintaining body balance was greater among people with MS compared to healthy adults. Both groups similarly relied more on the proprioceptive input to keep body balance than on the vision. ConclusionsLike healthy individuals, persons with MS rely more on proprioception to maintain body balance than vision. Our findings could provide preliminary reference for optimizing balance improving programs aimed at person with MS.

The interplay between cognitive tasks and vision for upright posture balance in adolescents.

BackgroundThe control of an upright stance in humans is important in medicine, psychology, and physiology. The maintenance of upright stance balance depends not only on sensory information from proprioceptive, vestibular, cutaneous, and visual sources but also on cognitive resources. The present study investigated the effects of cognitive tasks while standing with eyes open on upright stance balance in adolescents. We hypothesized that performing a cognitive task while standing with eyes open would increase body sway among these adolescents and that the upright posture would thus become less stable.MethodsA static balance assessment system comprising a force platform connected to a computer was used to evaluate the stability of the upright stance among 21 healthy adolescents under six conditions: no cognitive task, a relatively easy cognitive task, or the same cognitive task made more difficult, with each task being performed while the eyes were open and again while the eyes were closed. The participants performed mental calculations as fast as possible by subtracting either 3 or 18 from a random three-digit number continuously, for the simple cognitive task or the difficult cognitive task, respectively. Each calculation was completed within 10 s. The evaluation indexes used to measure upright posture stability were the root mean square (RMS) of the total body sway in the mediolateral and anteroposterior directions, the mean velocity (MV) value of the total body sway, and the Romberg quotient (RQ) of these values.ResultsThe RMS (p < 0.01) and MV (p < 0.01) values of the upright posture sway were lower when participants performed no cognitive task and their eyes were open than when their eyes were closed. When their eyes were open, compared with no cognitive task, the values of the measures evaluating upright posture sway were higher, meaning the stance was less stable, while performing either the simple or the more difficult cognitive task (RMS: simple task, p < 0.01; difficult task, p < 0.05; MV: simple task, p < 0.01; difficult task, p < 0.01) although no significant differences were detected for the RMS or MV values between the simple and more difficult cognitive tasks. The RQs for both the RMS and the total MV values of the upright posture sway during performance of the difficult cognitive task were significantly lower than when the participants performed no task.ConclusionPerformance of a cognitive task significantly reduced the upright posture balance in adolescents during eyes open although increased task difficulty did not show a greater effect. The interference between the performance of a cognitive task and the visual control of an upright stance may be attributable in part to cognitive and visual processing streams competing for common central resources, consistent with the Multiple Resource Theory of information processing.

Visual capture of gait during redirected walking

Redirected walking allows users of virtual reality applications to explore virtual environments larger than the available physical space. This is achieved by manipulating users’ walking trajectories through visual rotation of the virtual surroundings, without users noticing this manipulation. Apart from its applied relevance, redirected walking is an attractive paradigm to investigate human perception and locomotion. An important yet unsolved question concerns individual differences in the ability to detect redirection. Addressing this question, we administered several perceptual-cognitive tasks to healthy participants, whose thresholds of detecting redirection in a virtual environment were also determined. We report relations between individual thresholds and measures of multisensory weighting (visually-assisted postural stability (Romberg quotient), subjective visual vertical (rod-and-frame test) and illusory self-motion (vection)). The performance in the rod-and-frame test, a classical measure of visual dependency regarding postural information, showed the strongest relation to redirection detection thresholds: The higher the visual dependency, the higher the detection threshold. This supports the interpretation of users’ neglect of redirection manipulations as a “visual capture of gait”. We discuss how future interdisciplinary studies, merging the fields of virtual reality and psychology, may help improving virtual reality applications and simultaneously deepen our understanding of how humans process multisensory conflicts during locomotion.

Association between Falls and Balance among Inpatients with Schizophrenia: A Preliminary Prospective Cohort Study.

Falls are adverse events affecting psychiatric inpatients that can lead to external injuries, fractures, and death. However, none have attempted to examine fall-related factors, particularly focused on balance, specifically among inpatients with schizophrenia. The present preliminary study aimed to assess the association between falls and balance in patients with schizophrenia. The authors performed baseline assessments of background factors, postural sway, and maximum step length in 120 patients with schizophrenia hospitalized in the psychiatric ward. A prospective 3-month follow-up was conducted, and participants were divided into a fall or non-fall group according to their history of falls during the follow-up. Variance among individual variables was compared between the fall group and non-fall group using the t-test, Mann-Whitney U test, and chi-square test. A total of 16 participants experienced falls in the 3-month follow-up period (13.3%). Comparative factor analysis revealed significant differences between the fall and non-fall groups in terms of the presence or absence of falls within 3months before follow-up (p = 0.002) and Romberg quotients for sway length (p = 0.02). These findings suggest that fall history could be considered a predictor of future falls, which could help with fall prevention, and that assessment of visual contribution to postural control using the Romberg quotient could play an important role in fall prevention.

Characterizing postural oscillation in children and adolescents with hereditary sensorimotor neuropathy.

Charcot Marie Tooth disease (CMT) has negative functional impact on postural control of children; however, it has not been widely studied. Stabilometry can provide insights about postural control and guide preventive interventions in immature perceptual and musculoskeletal systems as those seen in children with CMT. This cross-sectional study aimed to identify and interpret stabilometric variables that reflect the postural control of children with CMT. 53 subjects (age 6–17) were assigned to one of the two groups: CMT (15 males and 14 females with CMT) or Control (13 males and 11 females healthy). Quiet standing was tested in different conditions: with open and closed eyes on regular surface (open-regular, closed-regular) and foam surface (open-foam, closed-foam) using a force platform. The minimum of 2 and maximum of 3 trials of 30 seconds for each test condition provided the classical stabilometric variables and Romberg Quotient (RQv). CMT group showed increase of confidence ellipse area, mean velocity, mediolateral and anteroposterior velocities associated with decreased mean body oscillation frequency, as the complexity of tasks increased. CMT postural deficit was identified by greater and faster sway associated with these lower frequencies, when compared to Control.

Influence of both cutaneous input from the foot soles and visual information on the control of postural stability in dyslexic children

Dyslexic children show impaired in postural stability. The aim of our study was to test the influence of foot soles and visual information on the postural control of dyslexic children, compared to non-dyslexic children. Postural stability was evaluated with TechnoConcept® platform in twenty-four dyslexic children (mean age: 9.3±0.29years) and in twenty-four non-dyslexic children, gender- and age-matched, in two postural conditions (with and without foam: a 4-mm foam was put under their feet or not) and in two visual conditions (eyes open and eyes closed). We measured the surface area, the length and the mean velocity of the center of pressure (CoP). Moreover, we calculated the Romberg Quotient (RQ). Our results showed that the surface area, length and mean velocity of the CoP were significantly greater in the dyslexic children compared to the non-dyslexic children, particularly with foam and eyes closed. Furthermore, the RQ was significantly smaller in the dyslexic children and significantly greater without foam than with foam. All these findings suggest that dyslexic children are not able to compensate with other available inputs when sensorial inputs are less informative (with foam, or eyes closed), which results in poor postural stability. We suggest that the impairment of the cerebellar integration of all the sensorial inputs is responsible for the postural deficits observed in dyslexic children.

Impairments of balance, stepping reactions and gait in people with cervical dystonia

BackgroundImpaired balance is common in neurological disorders. Cervical dystonia is a neurological movement disorder affecting the neck. The effect of this aberrant head posture on physical function is unknown. ObjectivesTo compare balance, mobility, gait and stepping reactions between ten people with cervical dystonia and ten control adults. MethodsSpatiotemporal gait parameters and walking speed were assessed using a computerised walkway. Step length and time, time in double support and gait variability were calculated, then normalised to gait speed. Centre of pressure path length was assessed with eyes open and eyes closed to calculate a Romberg Quotient. Simple and choice reaction times were measured using customised apparatus while mobility was assessed by the timed up and go. Cervical spine range of motion was measured using a head mounted goniometer. Self-reported scales included Falls Self Efficacy Scale and Dystonia Discomfort Scale. ResultsThere was a difference between groups for most outcome measures. The timed up-and-go and walking speed was slower (both P < 0.005) and the Romberg Quotient lower (P = 0.046) in cervical dystonia. People with cervical dystonia had lower falls self-efficacy (P = 0.0002). Reduced cervical range of motion was correlated with balance, stepping reaction time and mobility (all P < 0.05). Timed up and go was positively associated with stepping reaction time (P < 0.01). Dystonia discomfort did not impact function. ConclusionsPeople with cervical dystonia displayed deficits in balance, gait and stepping reactions, and expressed higher fear of falling. Studies to further elucidate functional limitations and their impact on activity and participation in daily life are required.

Imbalance in multiple sclerosis and neuromyelitis optica: association with deep sensation disturbance.

Abnormality in balance is one of the most important causes of gait disturbance which has a direct impact to disability and medical cost in multiple sclerosis (MS) and neuromyelitis optica (NMO). However, characteristics of imbalance in these two diseases have not been fully elucidated. The aim of this study was to evaluate the degree and features of imbalance using stabilography, the degree of deep sensation disturbance using tibial nerve somatosensory evoked potentials (SEP), and their association with clinical impairment, in patients with MS and NMO. Seven NMO patients and seven MS patients with balance disturbance were examined. The relationship among stabilography measurements representing the degree and features of imbalance, height-adjusted P38 peak latency of SEP, and neurological functional disability, were analyzed. Stabilography evaluation showed a significantly severer degree of imbalance in NMO than in MS. Romberg quotient of the patients with brainstem lesions was significantly larger than those without them. In all patients, length of excursion per second significantly correlated positively with anterio-posterior-axis power spectra at intermediate frequency band. In all patients and in NMO, P38 peak latency adjusted by height significantly correlated positively with anterio-posterior-axis power spectra at intermediate frequency band. These findings suggest that the degree of imbalance of MS and NMO possibly correlate with deep sensation disturbance, which could be evaluated by anterio-posterior-axis power spectra at intermediate frequency band by stabilography. Severer imbalance in NMO than MS may be associated with the severe longitudinally extensive spinal cord lesions.

Vestibular function in patients with Niemann-Pick type C disease.

We investigated whether vestibular dysfunction may cause or contribute to postural imbalance and falls in patients with Niemann-Pick type C disease (NP-C). Eight patients with NP-C disease and 20 healthy controls were examined using the video-based head impulse test (vHIT) and caloric irrigation to investigate horizontal canal function as well as ocular- and cervical vestibular evoked myogenic potentials (o- and cVEMP), and binocular subjective visual vertical estimation (SVV) for otolith function, and static posturography. There were no significant differences in vestibulo-ocular gain, caloric excitability, o-/cVEMP measures or SVV between the two groups. Posturographic total sway path (tSP) and root mean square (RMS) were significantly higher in NP-C than in controls in 3 out of 4 conditions. The Romberg quotient (RQ) to assess the amount of visual stabilization was significantly lower in the NP-C than in the HC group. In contrast to other inherited metabolic disorders, such as Morbus Gaucher type 3, we did not find any evidence for an impairment of canal or otolith function in patients with NP-C as their cause of postural imbalance. Since RQ was low in NP-C patients, indicating proper sensory input, the observed increased postural sway is most likely due to a cerebellar dysfunction in NP-C, which may therefore, explain postural imbalance.

Correlations Between Foam Posturography and Vestibular-Evoked Myogenic Potential Tests in Ménière’s Disease

This study adopted foam posturography coupled with inner ear test battery including audiometry, and cervical Vestibular-Evoked Myogenic Potential (cVEMP), ocular Vestibular-Evoked Myogenic Potential (oVEMP) and Caloric tests in patients with Ménière's disease to investigate the relations between them. Fifty patients with unilateral definite Ménière's disease were enrolled. All patients underwent Audiometry, and Caloric, oVEMP, and cVEMP tests. In addition, posturography was also performed under 4 conditions: A (firm surface, eyes open), B (firm surface, eyes closed), C (foam pad, eyes open), and D (foam pad, eyes closed). Romberg quotient (RQ) was measured as the value from eyes closed divided by that from eyes open. No correlation existed between Ménière stage and RQ measured with foam pad. Mean RQ of the sway area on foam pad in Ménière's patients with abnormal oVEMPs (1.75 ± 0.95) was significantly larger than 1.20 ± 0.70 in those with normal oVEMPs. However, neither cVEMP nor Caloric test results were associated with RQ on foam pad (p > 0.05). Further, the area under the receiver operating characteristic curve of the RQ of sway area on foam pad in discrimination between normal and abnormal oVEMP test was 0.65 (95% CI, 0.51 to 0.79; p < 0.05), implying that RQ of the sway area on foam pad may serve as a significant predictor for abnormal oVEMP test. By removing or reducing both visual and somatosensory inputs from foam posturography, the remaining vestibular cue, represented as RQ of sway area on foam pad, may reflect utricular function.

Effects of 12-Week Proprioception Training Program on Postural Stability, Gait, and Balance in Older Adults

The purpose of this study was to evaluate the effect of a 12-week-specific proprioceptive training program on postural stability, gait, balance, and fall prevention in adults older than 65 years. The present study was a controlled clinical trial. Forty-four community dwelling elderly subjects (61-90 years; mean age, 78.07 ± 5.7 years) divided into experimental (n = 20) and control (n = 24) groups. The participants performed the Berg balance test before and after the training program, and we assessed participants' gait, balance, and the risk of falling, using the Tinetti scale. Medial-lateral plane and anterior-posterior plane displacements of the center of pressure, Sway area, length and speed, and the Romberg quotient about surface, speed, and distance were calculated in static posturography analysis (EPS pressure platform) under 2 conditions: eyes open and eyes closed. After a first clinical evaluation, patients were submitted to 12 weeks proprioception training program, 2 sessions of 50 minutes every week. This program includes 6 exercises with the BOSU and Swiss ball as unstable training tools that were designed to program proprioceptive training. The training program improved postural balance of older adults in mediolateral plane with eyes open (p < 0.05) and anterior-posterior plane with eyes closed (p < 0.01). Significant improvements were observed in Romberg quotient about surface (p < 0.05) and speed (p < 0.01) but not about distance (p > 0.05). After proprioception training, gait (Tinetti), and balance (Berg) test scores improved 14.66% and 11.47% respectively. These results show that 12 weeks proprioception training program in older adults is effective in postural stability, static, and dynamic balance and could lead to an improvement in gait and balance capacity, and to a decrease in the risk of falling in adults aged 65 years and older.

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

There is a natural symbiosis between vergence and vestibular responses. Deficits in vergence can lead to vertigo, disequilibrium, and postural instability. This study examines both vergence eye movements in patients with idiopathic bilateral vestibular loss, and their standing balance in relation to vergence. Eleven patients participated in the study and 16 controls. Bilateral loss of vestibular function was objectified with many tests; only patients without significant response to caloric tests, to video head impulse tests and without vestibular evoked myogenic potentials were included in the study.Vergence testing (from 8 patients and 15 controls)A LED display with targets at 20, 40, and 100 cm along the median plane was used to elicit vergence eye movements, recorded with the IRIS device.Standing balance (11 patients and 16 controls)Four conditions were run, each lasting 1 min: fixation of a LED at 40 cm (convergence of 9°), at 150 cm (convergence of 2.3°); this last condition was repeated with eyes closed. Comparison of the eyes closed-eyes open conditions at 150 cm allowed evaluation of the Romberg Quotient. In the forth condition, two LEDS, at 20 and at 100 cm, were light on, one after the other for 1 sec, causing the eyes to converge then diverge. Standing balance was recorded with an accelerometer placed at the back near the center of mass (McRoberts, Dynaport).ResultsVergenceRelative to controls, convergence eye movements in patients showed significantly lower accuracy, lower mean velocity, and saccade intrusions of significantly higher amplitude.BalanceThe normalized 90% area of body sway was significantly higher for patients than for controls for all conditions. Yet, similarly to controls, postural stability was better while fixating at near (sustained convergence) than at far, or while making active vergence movements. We argue that vestibular loss deteriorates convergence, but even deficient, convergence can be helpful for postural control.

Benefit of bi-ocular visual stimulation for postural control in children with strabismus.

Vision is important for postural control as is shown by the Romberg quotient (RQ): with eyes closed, postural instability increases relative to eyes open (RQ = 2). Yet while fixating at far distance, postural stability is similar with eyes open and eyes closed (RQ = 1). Postural stability can be better with both eyes viewing than one eye, but such effect is not consistent among healthy subjects. The first goal of the study is to test the RQ as a function of distance for children with convergent versus divergent strabismus. The second goal is to test whether vision from two eyes relative to vision from one eye provides better postural stability. Thirteen children with divergent strabismus and eleven with convergent strabismus participated in this study. Posturtography was done with the Techno concept device. Experiment 1, four conditions: fixation at 40 cm and at 200 cm both with eyes open and eyes covered (evaluation of RQ). Experiment 2, six conditions: fixation at 40 cm and at 200 cm, with both eyes viewing or under monocular vision (dominant and non-dominant eye). For convergent strabismus, the groups mean value of RQ was 1.3 at near and 0.94 at far distance; for divergent, it was 1.06 at near and 1.68 at far. For all children, the surface of body sway was significantly smaller under both eyes viewing than monocular viewing (either eye). Increased RQ value at near for convergent and at far for divergent strabismus is attributed to the influence of the default strabismus angle and to better use of ocular motor signals. Vision with the two eyes improves postural control for both viewing distances and for both types of strabismus. Such benefit can be due to complementary mechanisms: larger visual field, better quality of fixation and vergence angle due to the use of visual inputs from both eyes.

Balance Control in Glaucoma

To examine postural stability in glaucoma patients and subjects with no ocular disease. Twenty-four glaucoma (G) and 24 control (C) subjects participated (mean age [SD] G: 65.9 [5.5] years; C: 68.3 [5.2] years). Postural stability was measured using a force-balance platform under four conditions: eyes open/closed standing on a firm surface and eyes open/closed on a foam surface. Average magnitude of center of foot pressure displacement (root mean square [RMS]) was calculated in the anteroposterior (AP) direction. The Romberg Quotient (RQ) was used to evaluate the visual contribution to balance. The difference in sway between firm and foam standing evaluated the relative somatosensory contribution to balance. The binocular mean deviation (BinMD) score was calculated from Humphrey 24-2 SITA strategy tests. Glaucoma patients had a lower visual contribution to sway (AP RQ, G = 1.65 [0.44]; AP RQ, C = 2.25 [0.53], P = 0.0001), and higher relative somatosensory contribution to sway (change in AP RMS EYES open firm to foam standing: G = 4.12 [1.85] mm, C = 2.22 [2.04] mm, P = 0.002). BinMD was a significant predictor of balance (AP RQ versus BinMD β-coefficient = 0.58, P = 0.0001; change in AP RMS [eyes open "firm" to "foam"] versus BinMD β-coefficient = -0.35, P = 0.02). Glaucoma patients display differences in their visual and somatosensory contributions to quiet standing balance compared with control subjects, associated with the degree of binocular visual field loss. This suggests that balance control may be compromised in this patient group.