Dynamic Visual Acuity Scores Research Articles

A treadmill running research protocol to assess dynamic visual acuity and balance for athletes with and without recent concussion history

Athletes interpret dynamic visual scenes quickly and accurately during physical exertion. It is important to understand how increased exertion may impact vision and cognition following sport-related concussion (SRC).Purpose To examine the effect of a treadmill running research protocol on the assessment of dynamic visual acuity (DVA) and balance for athletes with and without recent history of SRC.Methods Varsity athletes following recent SRC (CONC=12) were compared to athletes without SRC (ATHLETE=19). The DVA task presented a Tumbling ‘E’ target in four possible orientations during random walk (RW) or horizontal (H) motion at a speed of 30°/s. Participants performed DVA trials standing on a force plate (1000Hz) at four time points: 1) pre-exercise (PRE-EX), 2) immediately (POST1), 3) 10-minutes (POST10), and 4) 20-minutes post- exercise (POST20). Performance was calculated as a change in DVA score from PRE-EX and median response time (RT, ms). Balance control was analyzed using the root mean square of centre of pressure displacement (dCOP).Results Both groups maintained DVA scores for both motion types and exhibited immediate exercise-induced benefits on RT. Both groups had similar change in balance control strategy following treadmill exercise.Conclusion Both groups elicited similar exercise-induced benefits on DVA following exercise. A repeated measures assessment following vigorous exercise may provide meaningful insights about visual and neurocognitive functions for athletes returning to sport following concussion.

Developing a serious game for gaze stability rehabilitation in children with vestibular hypofunction

BackgroundChildren with vestibular hypofunction (VH) may have gaze instability, balance disorders, and delayed postural-motor development. Gaze stabilization exercises (GSE) are designed to improve dynamic visual acuity (DVA). We aimed to assess the acceptability of a serious game prototype called Kid Gaze Rehab (KGR) designed to implement GSE training in children with VH, combined with traditional vestibular rehabilitation. Effects on DVA and motor performance were also analyzed.MethodsTwelve children (6 to 9 years old) were included. Sessions were held at the hospital twice a week, for 5 weeks. An adapted French version of The Child Simulator Sickness Questionnaire (SSQ) and the Face Scale Pain-Revised (FPS-R) were used to assess pain in the cervical region and undesirable side effects after each session. Vestibular and motor function parameters (active and passive DVA and Movement Assessment Battery for Children–Second Edition, MABC-2) were assessed before and after the training.ResultsAll children included completed the 10 sessions. The FPS-R visual analog scale and SSQ showed good cervical tolerance and no oculomotor or vegetative adverse effects nor spatial disorientation. After training, active DVA scores were significantly improved for the right, left, and up directions (p < 0.05). Passive DVA scores were significantly improved for the left and down directions (p < 0.01 and p < 0.05, respectively). MABC-2 scores were improved in the balance and ball skill sections (p < 0.05).ConclusionAn innovative pediatric training method, the use of a dedicated serious game for gaze stabilization was well-tolerated as a complement to conventional vestibular rehabilitation in children with VH. Moreover, both DVA and motor performance were found to improve in the study sample. Although replication studies are still needed, serious game-based training in children with VH could represent a promising rehabilitation approach for years to come.Trial registrationThe study was conducted in accordance with the Declaration of Helsinki and approved by an Institutional Review Board (local ethics committee, CPP Sud-Est IV, ID 2013–799). The study protocol was registered on ClinicalTrials.gov (NCT04353115).

Effects of vestibular rehabilitation in patients with unilateral vestibular hypofunction

Purpose: To investigate the effect of physiotherapy on the balance parameters and fall risk in patients with unilateral vestibular hypofunction (UVH). Patients and Methods: Thirty patients diagnosed with UVH were included in the study. The number of falls, Visual Analog Scale, Modified Clinical Test for Sensory Interaction in Tandem and Balance, and dynamic visual acuity assessments was performed before and after treatment. The patients were included in an individual treatment program for 8 weeks. Physiotherapy sessions were given at 2-week intervals. Along with the level of development of the treatment applied to the patients, it was requested perform a home exercise program with ten repetitions three times a day. Results: After 8 weeks of vestibular rehabilitation, it was observed that the balance parameters of the participants improved and the number of falls decreased. Statistically significant results were obtained in the Eyes-closed Tandem test (P = 0.001). Significant changes occurred in the modified Clinical Test results for Sensory Interaction in Balance from 0.37 ± 0.19 s to 0.93 ± 0.11 s (P = 0.001). Vestibular symptoms and dynamic visual acuity scores also improved after treatment (P = 0.001). Conclusion: It was concluded that the physiotherapy program applied to our patients with UVH positively affected fall risk and significantly improved balance parameters.

Efficacy of Computerized Visual Tracking Technology Throughout Concussion Recovery: A Case Series

<h3>Research Objectives</h3> To compare results of computerized eye tracking assessments to concussion patient reported outcomes and other objective oculomotor function tests throughout the concussion recovery. <h3>Design</h3> Retrospective case series of three physical therapy plan of cares completed between April 2021 and September 2021. <h3>Setting</h3> Outpatient physical rehabilitation clinic. <h3>Participants</h3> Included three female patients (mean age 34.7 years). Brain injury conditions vary from sub-acute to chronic. Selected via volunteer sample. <h3>Interventions</h3> Manual therapy, postural stabilization, aerobic conditioning, ocular motor training, and balance exercises. Average physical therapy visit count of 15.3. <h3>Main Outcome Measures</h3> RightEye™ Dynamic Visual Acuity (DVA) Test, Concussion Clinical Profile Screen (CCPS), Clinical DVA, Somatosensory Organization Test (SOT), and Vestibular Ocular Motor Screen (VOMS). <h3>Results</h3> All final RightEye™ DVA composite scores declined or had minimal change compared to evaluation scores. Initial VOMS similar findings to initial RightEye™ DVA subdomain scores. CCPS composite and ocular profile scores improved with each re-assessment. Clinical DVA scores improved and within normal limits at final assessments. 2/3 of participants had normal composite scores on SOT at re-evaluation. <h3>Conclusions</h3> In this case series subjective recovery of concussion symptoms did not correlate with performance on computerized ocular motor assessments. There were conflicting results on several other objective tests compared to results of RightEye™ DVA. Some confounding factors that may have impacted scores are co-morbidities of cervical pain, anxiety, depression, and migraine. Even though the assessments did not correlate, it is important to note the tracking assessments and games were engaging and offered repetition. In conclusion, clinicians should not rely on one single measurement for concussion screening and determination of readiness for return to prior activities. More research is needed to determine the efficacy of computerized visual tracking assessments for individuals with complex medical history and post-concussion. <h3>Author(s) Disclosures</h3> The author has nothing to disclose.

Dynamic Visual Acuity Results in Otolith Electrical Stimulation in Bilateral Vestibular Dysfunction.

(1) Background. Patients with bilateral vestibular disease (BVD) experience oscillopsia with a detriment to visual acuity (VA). This VA is driven mainly by the VOR that has two components: rotational and translational. VA can be tested by using dynamic visual acuity (DVA) on a treadmill because both systems are activated. The aim of this study is to compare VA before and after chronic electrical stimulation of the otolith organ. (2) Materials and Method. Five patients suffering from bilateral vestibular dysfunction (BVD), previously implanted with a new vestibular implant prototype, were included in this study with the aim to check VA with and without vestibular implant use (W and W/O) in static, 2 km/h and 4 km/h walking situations. DVAtreadmill was measured on a treadmill with a dynamic illegible E (DIE) test in static and dynamic conditions (while walking on the treadmill at 2 and 4 km/h). The DVA score was registered in a logarithm of the minimum angle of resolution (LogMAR) for each speed. In addition, every patient completed the oscillopsia severity questionnaire (OSQ) and video head impulse test (vHIT) before and after activation of the vestibular implant. (3) Results. The analysis shows a significant difference in OSQ scores and DVA with an improvement in dynamic conditions. Organized corrective saccades during the use of a vestibular implant with no changes in gain were also detected in the video head impulse tests (vHIT). (4) Conclusion. The vestibular implant with otolithic stimulation offers changes in the response of DVA, which makes this paper one of the first to address the possible restoration of it. It is not possible to rule out other contributing factors (presence of covert saccades, somatosensory system, …). More work seems necessary to understand the neurophysiological basis of these findings, but this implant is added as a therapeutic alternative for the improvement of oscillopsia.

Dynamic visual acuity test findings of migraine patients: Observational case-control study

ObjectiveTo evaluate computerized dynamic visual acuity (DVA) test findings among patients with migraine and to determine whether self-motion sensitivity and visually induced migraine symptoms that are seen in migraine patients can be explained by DVA results. MethodsTwenty migraine patients and twenty control subjects were evaluated with DVA test during rapid horizontal (left and right) and vertical (up and down) head movements. The subjects were asked to quickly recognize the direction of the Landolt-C optotype on the monitor while moving their heads. Test began with the largest optotype and progressively decreased in size by 0.1 logMAR until the subject could no answer correctly state the orientation of the optotype. DVA test scores of migraine group and control group were compared. ResultsPatient with migraine had significant DVA loss as compared with control subjects in four positions (left DVA, right DVA, up DVA, down DVA respectively p < 0.001, <0.001 = 0.001 and <0.001). ConclusionMigraine patients were found to have abnormal DVA scores mediated vestibular-ocular reflex. These abnormal DVA findings can explain the pathophysiology of head motion hypersensitivity and visual motion sensitivity that encountered by migraine patients.

Leveraging virtual reality for vestibular testing: Clinical outcomes from tests of dynamic visual acuity.

Virtual reality (VR) use as a platform for vestibular rehabilitation is widespread. However, the utility of VR based vestibular assessments remains unknown. To compare dynamic visual acuity (DVA) scores, perceived balance, and perceived dizziness when using traditional versus VR environments for DVA testing among healthy individuals. DVA testing occurred for both a traditional clinical protocol and in a VR variant. Horizontal, vertical, and no head motion conditions were conducted for both clinical and VR test protocols. DVA scores, balance ratings, and dizziness ratings were obtained per condition. Two-way ANOVAs with repeated measures were used to assess differences in DVA scores, balance, and dizziness ratings. No differences in DVA results, balance or dizziness ratings were observed when comparing traditional clinical protocol versus the VR variant. Differences across head motion conditions were observed, with no motion trials exhibiting significantly higher DVA scores and perceived balance, and lower perceived dizziness compared to vertical and horizontal head motion. Vertical head motion exhibited this same trend compared to horizontal. DVA testing conducted in VR demonstrated clinical utility for each measure. Effects of head motion were similar across test variants, indicating DVA testing in VR produces similar effects on vestibular function than traditional clinical testing. Additional research should be conducted to assess the feasibility of VR assessment in individuals with vestibular disorder.

Once-Daily Incremental Vestibular-Ocular Reflex Adaptation Training in Patients With Chronic Peripheral Vestibular Hypofunction: A 1-Week Randomized Controlled Study

This was a double-blinded randomized controlled study to investigate the effects of once-daily incremental vestibulo-ocular reflex (VOR) training over 1 week in people with chronic peripheral vestibular hypofunction. A total of 24 patients with peripheral vestibular hypofunction were randomly assigned to intervention (n = 13) or control (n = 11) groups. Training consisted of either x1 (control) or incremental VOR adaptation exercises, delivered once daily for 15 minutes over 4 days in 1 week. Primary outcome: VOR gain with video-oculography. Secondary outcomes: Compensatory saccades measured using scleral search coils, dynamic visual acuity, static balance, gait, and subjective symptoms. Between-group differences were analyzed with a linear mixed-model with repeated measures. There was a difference in the VOR gain increase between groups (P < 0.05). The incremental training group gain increased during active (13.4% ± 16.3%) and passive (12.1% ± 19.9%) head impulse testing (P < 0.02), whereas it did not for the control group (P = 0.59). The control group had reduced compensatory saccade latency (P < 0.02). Both groups had similarly improved dynamic visual acuity scores (P < 0.05). Both groups had improved dynamic gait index scores (P < 0.002); however, only the incremental group had improved scores for the 2 walks involving head oscillations at approximately 2 Hz (horizontal: P < 0.05; vertical: P < 0.02), increased gait speed (P < 0.02), and step length (P < 0.01) during normal gait, and improved total Dizziness Handicap Inventory (P < 0.05). Our results suggest incremental VOR adaptation significantly improves gain, gait with head rotation, balance during gait, and symptoms in patients with chronic peripheral vestibular hypofunction more so than conventional x1 gaze-stabilizing exercises.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A336).

Rehabilitation of dynamic visual acuity in patients with unilateral vestibular hypofunction: earlier is better.

Patients with acute peripheral unilateral hypofunction (UVH) complain of vertigo and dizziness and show posture imbalance and gaze instability. Vestibular rehabilitation therapy (VR) enhances the functional recovery and it has been shown that gaze stabilization exercises improved the dynamic visual acuity (DVA). Whether the effects of VR depend or not on the moment when it is applied remains however unknown, and investigation on how the recovery mechanisms could depend or not on the timing of VR has not yet been tested. Our study investigated the recovery of DVA in 28 UVH patients whose unilateral deficit was attested by clinical history and video head impulse test (vHIT). Patients were tested under passive conditions before (pre-tests) and after (post-tests) being subjected to an active DVA rehabilitation protocol. The DVA protocol consisted in active gaze stabilization exercises with two training sessions per week, each lasting 30 min, during four weeks. Patients were sub-divided into three groups depending on the time delay between onset of acute UVH and beginning of VR. The early DVA group (N = 10) was composed of patients receiving the DVA protocol during the first 2 weeks after onset (mean = 8.9 days), the late group 1 (N = 9) between the 3rd and the 4th week (mean = 27.5 days after) and the late group 2 (N = 9) after the 1st month (mean: 82.5 days). We evaluated the DVA score, the angular aVOR gain, the directional preponderance and the percentage of compensatory saccades during the HIT, and the subjective perception of dizziness with the Dizziness Handicap Inventory (DHI). The pre- and post-VR tests were performed with passive head rotations done by the physiotherapist in the plane of the horizontal and vertical canals. The results showed that patients submitted to an early DVA rehab improved significantly their DVA score by increasing their passive aVOR gain and decreasing the percentage of compensatory saccades, while the late 1 and late 2 DVA groups 1 and 2 showed less DVA improvement and an inverse pattern, with no change in the aVOR gain and an increase in the percentage of compensatory saccades. All groups of patients exhibited significant reductions of the DHI score, with higher improvement in subjective perception of dizziness handicap in the patients receiving the DVA rehab protocol in the first month. Our data provide the first demonstration in UVH patients that earlier is better to improve DVA and passive aVOR gain. Gaze stabilization exercises would benefit from the plastic events occurring in brain structures during a sensitive period or opportunity time window to elaborate optimal functional reorganizations. This result is potentially very important for the VR programs to restore the aVOR gain instead of recruiting compensatory saccades assisting gaze stability.

Customized Vestibular Rehabilitation in the Patients with Bilateral Vestibulopathy: A Pilot Study in One Referred Center

Objectives: Bilateral vestibulopathy is characterized with unsteadiness and oscillopsia when walking or standing, worsening in darkness and/or on uneven ground. To establish the effect of customized vestibular rehabilitation in bilateral vestibulopathy, we analyzed the questionnaires and functional status before and after treatment. Methods: Among 53 patients with customized vestibular rehabilitation from January 1st to November 30th in 2018, 6 patients (3 males; median age, 71 years; range, 54–75 years) who regularly exercised with good compliance were retrospectively enrolled. They were educated and trained the customized vestibular rehabilitation once a month or two by a supervisor during 40 minutes, and then exercised at home for 30 minutes over 5 days in a week. Dizziness handicap inventory (DHI), Korean vestibular disorders activities of daily living scale (vADL), Beck’s depression index (BDI), test for dynamic visual acuity (DVA), and Timed Up and Go test (TUG) were performed before and after the customized vestibular rehabilitation. Results: The patients exercised for median 5.5 months (range, 2–10 months) with the customized methods of vestibular rehabilitation, which included gaze and posture stabilization and gait control exercises. DHI score and TUG was improved after rehabilitation (DHI before vs. after rehabilitation=33 vs. 16, p=0.027, TUG before vs. after rehabilitation=12 vs. 10, p=0.026). BDI, DVA, and vADL scores did not differ between before and after treatment. Conclusions: Customized vestibular rehabilitation can improve dizziness and balance state in bilateral vestibulopathy. The steady exercises adapted individual peculiarities is the most important for vestibular rehabilitation. Keywords: Bilateral vestibulopathy; Vestibular rehabilitation; Customized vestibular rehabilitation; Dizziness handicap inventory 중심 단어: ì–‘ì¸¡ì„±ì „ì •ê¸°ëŠ¥ìž¥ì• , ì „ì •ìž¬í™œ, ë§žì¶¤í˜•ì „ì •ìž¬í™œ, 어지럼척도

Correlation of Head Impact Exposures With Vestibulo-Ocular Assessments.

Managing a concussion injury should involve the incorporation of a multifaceted approach, including a vision assessment. The frontoparietal circuits and subcortical nuclei are susceptible to trauma from a concussion injury, leading to dysfunction of the vestibulo-ocular system. Research investigating the effect of cumulative subconcussive impacts on neurological function is still in its infancy, but repetitive head impacts may result in vestibular system dysfunction. This dysfunction could create visual deficits, predisposing the individual to further head trauma. The purpose of this study was to investigate the cumulative effect of subconcussive impacts on minimum perception time, static visual acuity, gaze stability, and dynamic visual acuity scores. Prospective cohort. Division I university. Thirty-three Division I men's lacrosse players (age = 19.52 [1.20]y). Competitive lacrosse season. At the beginning and end of the season, the players completed a vestibulo-ocular reflex assessment, using the InVision™ system by Neurocom® to assess perception, static acuity, gaze stability, and dynamic visual acuity. Score differentials were correlated with the head impact exposure data collected via instrumented helmets. A significant correlation was found between change in perception scores and total number of head impacts (r = .54), and between changes in dynamic visual acuity loss scores on the rightside and maximum rotational acceleration (r = .36). No statistical differences were found between preseason and postseason vestibulo-ocular reflex variables. Cumulative subconcussive impacts may negatively affect vestibulo-ocular reflex scores, resulting in decreased visual performance. This decrease in vestibulo-ocular function may place the athlete at risk of sustaining additional head impacts or other injuries.

Vestibular Assessments in Children With Global Developmental Delay: An Exploratory Study.

To compare results of 3 clinical vestibular tests between children with global developmental delay (GDD) and children with typical development (TD) and investigate the test-retest reliability. Twenty children with GDD (aged 4.1-12.1 years) and 11 age-matched controls with TD participated. Participants with GDD underwent 2 sessions of testing. Each session consisted of the Clinical Test of Sensory Interaction and Balance (CTSIB), Dynamic Visual Acuity (DVA) test, and the modified Emory Clinical Vestibular Chair Test (m-ECVCT). Up to 33% of the children with GDD had abnormal DVA scores. m-ECVCT results of children with GDD demonstrated larger variance than children with TD. The CTSIB score was significantly reduced in the group with GDD. The test-retest reliability varied, with good reliability for the m-ECVCT and CTSIB, and fair reliability for the DVA. Findings suggest vestibular involvement in children in GDD. The clinical tests demonstrated moderate test-retest reliability.

Ethanol consumption impairs vestibulo-ocular reflex function measured by the video head impulse test and dynamic visual acuity.

Ethanol affects many parts of the nervous system, from the periphery to higher cognitive functions. Due to the established effects of ethanol on vestibular and oculomotor function, we wished to examine its effect on two new tests of the vestibulo-ocular reflex (VOR): the video head impulse test (vHIT) and dynamic visual acuity (DVA). We tested eight healthy subjects with no history of vestibular disease after consumption of standardized drinks of 40% ethanol. We used a repeated measures design to track vestibular function over multiple rounds of ethanol consumption up to a maximum breath alcohol concentration (BrAC) of 1.38 per mil. All tests were normal at baseline. VOR gain measured by vHIT decreased by 25% at the highest BrAC level tested in each subject. Catch-up saccades were negligible at baseline and increased in number and size with increasing ethanol consumption (from 0.13° to 1.43° cumulative amplitude per trial). DVA scores increased by 86% indicating a deterioration of acuity, while static visual acuity (SVA) remained unchanged. Ethanol consumption systematically impaired the VOR evoked by high-acceleration head impulses and led to a functional loss of visual acuity during head movement.

The Under-compensatory Roll aVOR Does Not Affect Dynamic Visual Acuity

Rotations of the head evoke compensatory reflexive eye rotations in the orbit to stabilize images onto the fovea. In normal humans, the angular vestibulo-ocular reflex (aVOR) gain (eye/head velocity) changes depending on the head rotation plane. For pitch and yaw head rotations, the gain is near unity, but during roll head rotations, the aVOR gain is ∼ 0.7. The purpose of this study was to determine whether this physiological discrepancy affects dynamic visual acuity (DVA)--a functional measure of the aVOR that requires subjects to identify letters of varying acuities during head rotation. We used the scleral search coil technique to measure eye and head velocity during passive DVA testing in yaw, roll, and pitch head impulses in healthy controls and patients with unilateral vestibular hypofunction (UVH). For control subjects, the mean aVOR gain during roll impulses was significantly lower than the mean aVOR gain during yaw and pitch impulses; however, there was no difference in DVA between yaw, roll, or pitch. For subjects with UVH, only aVOR gain during head rotations toward the affected side (yaw) were asymmetric (ipsilesional, 0.32 ± 0.17, vs. contralesional, 0.95 ± 0.05), with no asymmetry during roll or pitch. Similarly, there was a large asymmetry for DVA only during yaw head rotations, with no asymmetry in roll or pitch. Interestingly, DVA during roll toward the affected ear was better than DVA during yaw toward the affected ear--even though the ipsilesional roll aVOR gain was 60 % lower. During roll, the axis of eye rotation remains nearly perpendicular to the fovea, resulting in minimal displacement between the fovea and fixation target image projected onto the back of the eye. For subjects with UVH, the DVA score during passive horizontal impulses is a better indicator of poor gaze stability than during passive roll or pitch.

Comparison of Dynamic Visual Acuity Between Water Polo Players and Sedentary Students

In this study, we examined differences in dynamic visual acuity between elite and subelite water polo players and sedentary students. To measure dynamic visual acuity binocularly, we asked participants to indicate the orientation of a broken ring, similar to the Landolt C, which increased in size as it moved across a computer screen. Two different speeds, three possible trajectories, and two different levels of contrast were evaluated. There were statistically significant differences between elite players and sedentary students for each combination of speed, contrast, and trajectory. Elite players achieved better dynamic visual acuity scores, and results also improved for some combinations of speed, contrast, and trajectory. Comparison between elite and subelite groups failed to reveal any

Tracking Recovery of Vestibular Function in Individuals With Blast-Induced Head Trauma Using Vestibular-Visual-Cognitive Interaction Tests

Traumatic brain injury secondary to blast exposure is a significant international concern and a growing rehabilitation issue. Our objective was to determine whether a novel battery of vestibular-visual-cognitive interaction tests provides objective data to document functioning, and the changes in functioning associated with vestibular physical therapy (VPT) treatment, in individuals with blast-induced balance disorder. Eighty-two individuals with blast-induced mild traumatic brain injury were evaluated at baseline using a set of vestibular-visual-cognitive tests. Testing was repeated at 4-week intervals after beginning VPT. The tests included static visual acuity, perception time, target acquisition, target following (TF), dynamic visual acuity (DVA), and gaze stabilization tests. The VPT program consisted of exercise procedures that targeted the vestibulo-ocular reflex, cervico-ocular reflex, and depth perception. Somatosensory balance exercises, dynamic gait, and aerobic function exercises were also included. Participants attended VPT twice weekly for 1-hour appointments and were instructed to perform the exercises at home on other days. Mean test values were determined and compared with normative values previously collected in our laboratory from individuals without vestibular dysfunction. Mean participant pre-VPT measures for perception time and target acquisition were similar to normative values, and there was no significant change in these measures. Initially, TF and DVA scores were below normative levels but returned to normative levels after 8 weeks of VPT. Gaze stabilization scores were below normative levels pre-VPT but improved by the time of the week 8 evaluation. This battery of vestibular-visual-cognitive tests seems to be reasonable to establish initial status and to evaluate participant progress associated with participation in VPT. Our data suggest meaningful improvement in TF and DVA after 8 weeks of treatment. A treatment period of 12 weeks or longer may be required for gaze stabilization scores to return to normative values.

Dynamic visual acuity during head-thrust test in canal planes in healthy subjects and patients with vestibular neuritis

Conclusions: Dynamic visual acuity (DVA) during the head-thrust test (htDVA) is reliable in normal subjects, having a high specificity for the horizontal canal, so it may be useful to monitor vestibular rehabilitation in patients with vestibular neuritis (VN). Objective: To obtain reference values for htDVA in healthy individuals and to investigate the potential application in subjects with unilateral VN. Methods: A total of 73 healthy individuals and 50 patients with unilateral VN were included. The DVA test was performed by adjusting a sensor on the subject's head to measure head velocity. During head thrust, the optotype flashed if the head velocity reached 150°/s, as previously defined, and a DVA score was obtained for each canal. Results: The htDVA was reliable in normal subjects (intra-class correlation coefficient (ICC) = 0.44–0.71; p = 0.001–0.007). The htDVA score showed an age-dependent increase for all canals (p < 0.0001). The 95th percentile of htDVA was used as the criterion to consider htDVA as abnormal in patients with VN. In all, 44%, 30%, and 16% of patients had an increase in htDVA score for one, two or all three canals on the affected side. The sensitivity and specificity of the htDVA test for the horizontal canal were 22% and 85%, respectively.

Clinical Evaluation of Dynamic Visual Acuity in Subjects With Unilateral Vestibular Hypofunction

The objectives of this study are threefold: 1) to examine the effect of frequency of head motion on the clinical dynamic visual acuity (DVA) score in subjects with unilateral vestibular hypofunction (UVH); 2) to compare DVA scores between subjects with UVH and subjects with a complete unilateral vestibular deficit; and 3) to establish whether a relationship exists between the extent of the vestibular deficit and the DVA score. Experimental study. Vestibular outpatient rehabilitation program. A convenience sample of 10 subjects with UVH. Dynamic visual acuity scores were recorded using 2 standard acuity charts: Snellen and E-chart. The DVA scores were obtained at slow (0.5 Hz), moderate (1 and 1.5 Hz), and fast (2.0 Hz) frequencies of head motion in the horizontal and the vertical planes. Percentage of caloric weakness was compared with DVA scores in each subject to test whether a relationship exists between the two. As the frequency of head motion increased, the number of UVH subjects with an abnormal DVA score increased. Subjects with an abnormal DVA score at 1 Hz had the same or higher score as the frequency of the head motion was increased. Spearman correlation analyses revealed low-correlation coefficients between percentage of vestibular paresis at the caloric test and DVA scores (horizontal direction: r = 0.31, p = 0.38 for Snellen chart and r = -0.33, p = 0.35 for the E-chart; vertical: r = 0.05, p = 0.91 for the Snellen chart and r = -0.28, p = 0.50 for the E-chart). Subjects with UVH manifest impaired DVA. The frequency of head motion has an impact on clinical DVA scores in UVH subjects.

Active linear head motion improves dynamic visual acuity in pursuing a high-speed moving object

We usually move both our eyes and our head when pursuing a high-speed moving object. However, the vestibulo-ocular reflex (VOR), evoked by head motion, seems to disturb smooth pursuit eye movement because the VOR stabilizes the gaze against head motion. To determine whether head motion is advantageous for pursuing a high-speed moving object, we examined dynamic visual acuity (DVA) for a high-speed (80 degrees /s) rightward moving object with and without active linear rightward head motion (HM) at a maximum of 50 cm/s in nine healthy subjects. Furthermore, we analyzed eye and head movements to investigate the contribution of linear VOR (LVOR) and smooth eye movement under these conditions. In most subjects, active linear head motion improved DVA for a high-speed moving object. Subjects with higher DVA scores under HM had robust rightward gaze (eye + head) velocities (>60 cm/s), i.e., rightward smooth eye movements (>10 degrees /s). With the head stationary (HS), faster smooth eye movements (>40 degrees /s) were generated when the subjects pursued a high-speed moving object. They also showed anticipatory smooth eye movements under conditions HM and HS. However, the level of suppression of their LVOR abilities was equal to that of the others. These results suggest that the ability to generate anticipatory smooth pursuit eye movements for following a high-speed moving object against the LVOR is a determining factor for improvement of DVA under HM.

Incremental Exercise in Dynamic Visual Acuity

As research is limited the purpose of this study was to investigate dynamic visual acuity while cycling at different exercise loads. Accuracy of dynamic visual acuity scores of 20 college-age participants was analyzed by a repeated-measures analysis of variance which indicated improved dynamic visual acuity during cycling as the intensity of exercise increased. A retention test conducted two days after testing yielded evidence of trainability of dynamic visual acuity. In the discussion findings were compared to other visual functions associated with exercise.