Visual Field Occlusion Research Articles

Effect of auditory deprivation on adaptive locomotion: Interaction with lower visual field occlusion

Auditory stimuli have been suggested to play a role in adequately controlling movement; however, their influence is not fully understood, particularly regarding dynamic behaviors, such as adaptive locomotion. This study aimed to investigate whether auditory deprivation affects adaptive locomotion. In particular, we aimed to elucidate the role of the auditory sense in obstacle avoidance by manipulating the visual field, which provides crucial sensory information for movement control. Sixteen participants approached a 15-cm obstacle located 6 m away and stepped over it under four different conditions that combined two factors: the hearing condition controlled by wearing earmuffs with and without holes, and the lower visual field condition controlled by carrying opaque white and transparent boards. Spatiotemporal variables during the approach to the obstacle were measured using an electronic walkway, whereas foot clearance over the obstacle was assessed using a motion-capture system. Participants who experienced auditory deprivation and lower visual field occlusion demonstrated greater variability in step length when approaching the obstacle compared with the other conditions. The leading and trailing foot clearances were higher under lower visual field occlusion conditions. Furthermore, when participants were under conditions of auditory deprivation, greater variability was observed in the clearance of the leading foot. These results suggest that auditory information contributes to movement stabilization during adaptive locomotion. Our findings provide evidence that auditory and visual senses complement each other during motor actions, indicating that adaptive locomotion can be influenced by the integration of multiple sensory inputs.

Infrequent Giant Cutaneous Cavernous Hemangioma of the Eyelid

A 55-year-old man presented with a painless, well-circumscribed, and slowly growing mass on the right upper eyelid, present for 55 years. The mass was pedicled to the skin of the right upper eyelid. The mass was dark violet, resulting in complete mechanical ptosis and visual field occlusion (Fig A). Resection was performed via a cutaneous incision approach with an adjacent pedicled flap graft. The pathological diagnosis was cavernous hemangioma (Fig B). Most periocular cavernous hemangiomas are subcutaneous or orbital lesions, making our case an unusual presentation for this condition (Magnified version of Fig A-B is available online at www.aaojournal.org).

Sex Differences in the Visuomotor Control of Obstacle Crossing When Walking Are Not Age Related.

To ensure stable obstacle crossing when walking, visual information is required two steps before reaching the obstacle. As possible age-related sex differences in visuomotor control have not been investigated, we assessed sex differences in obstacle crossing while walking, as examined by toe clearance (TC) and postural stability. Participants were 14 younger and 14 older adults (equal numbers of men and women) who wore goggles for visual field adjustment while obstacle crossing during gait. We manipulated three visual field occlusion conditions (total, lower, and no visual field occlusions) two steps before the obstacle and analyzed the TC of the lead limb, and the participants' step width and root mean square of trunk acceleration as indices of postural stability. We found a significant interaction between sex and visual condition in step width, with men showing larger step width values than women in all visual field conditions. Moreover, while women showed no step-width differences across visual field conditions, men had a larger step width with the lower visual field occluded than in the other visual conditions. We found no other significant sex differences. Our results suggest that men may be more dependent than women on the upper visual field for postural stability during obstacle crossing. Sex differences in visuomotor control were not affected by age.

Incremental Visual Occlusion During Split-Belt Treadmill Walking Has No Gradient Effect on Adaptation or Retention.

Split-belt treadmills have become an increasingly popular means of quantifying ambulation adaptability. Multiple sensory feedback mechanisms, including vision, contribute to task execution and adaptation success. No studies have yet explored visual feedback effects on locomotor adaptability across a spectrum of available visual information. In this study, we sought to better understand the effects of visual information on locomotor adaptation and retention by directly comparing incremental levels of visual occlusion. Sixty healthy young adults completed a split-belt adaptation protocol, including a baseline, asymmetric walking condition (adapt), a symmetric walking condition (de-adapt), and another asymmetric walking condition (re-adapt). We randomly assigned participants into conditions with varied visual occlusion (i.e., complete and lower visual field occlusion, or normal vision). We captured kinematic data, and outcome measures included magnitude of asymmetry, spatial and temporal contributions to step length asymmetry, variability of the final adapted pattern, and magnitude of adaptation. We used repeated measures and four-way MANOVAs to examine the influence of visual occlusion and walking condition. Participants with complete, compared to lower visual field visual occlusion displayed less consistency in their walking pattern, evident via increased step length standard deviation (p = .007, d = 0.89), and compared to normal vision groups (p = .003 d = 0.81). We found no other group differences, indicating that varying levels of visual occlusion did not significantly affect locomotor adaptation or retention. This study offers insight into the role vision plays in locomotor adaptation and retention with clinical utility for improving variability in step control.

The influence of carrying an anterior load on attention demand and obstacle clearance before, during, and after obstacle crossing.

Carrying an anterior load during obstacle negotiation increases attention demand, which may differ at various crossing stages. Less is known on the impact of lower visual field obstruction and the weight of the anterior load on obstacle negotiation and attention demand. The objectives of this study were to: (1) determine if carrying a weighted anterior load, lower visual field occlusion, or both, modify obstacle clearance and/or reaction time (RT); and (2) examine whether RT is modulated across obstacle crossing phases as measured by a probe RT protocol. Sixteen young adults crossed an obstacle while carrying no load, a clear 5kg load, and an opaque 5kg load, while performing a simple RT task. Auditory stimuli were presented at five locations: (1) two steps before the obstacle; (2) one step before the obstacle; (3) as the leading limb crossed the obstacle; (4) as the lead limb touched down after the obstacle; and (5) as the trail limb crossed the obstacle. The toe clearance height of the leading limb was greatest for the weighted opaque box load type followed by the weighted clear box type compared to the no box load type. Carrying an anterior load during obstacle crossing did not influence RT. RTs were longer at the pre-crossing and beginning of the crossing phases compared to after-crossing phases. Results suggest that carrying a weighted anterior load and lower visual field occlusion increase the risk for tripping. Attention demands differ across obstacle crossing phases during dual-tasking and should be considered in fall-risk assessments.

Contribution of vision and its age-related changes to postural stability in obstacle crossing during locomotion

BackgroundObstacle crossing requires sufficient toe clearance for trip and fall prevention for which postural stability is a prerequisite. It is thought that the upper visual field plays an important role in the maintenance of postural stability, but its influence and age-dependence have not been investigated yet. Research questionWhat is the role of the visual fields in maintaining postural stability during crossing an obstacle in young and older adults?. MethodsThis study included 14 young adults and 14 older adults. The participants, wearing an accelerometer and liquid crystal shutter goggles, were asked to cross an obstacle under the following three conditions (i) full vision; (ii) total visual field occlusion at two steps before the obstacle, and (iii) lower visual field occlusion at two steps before the obstacle. The root mean square ratio in the mediolateral direction (RMSRML) for the three sections (i.e., approach to the obstacle, lead limb crossing, and trail limb crossing), as well as the root mean square in the mediolateral direction (RMSML) for each section were calculated. ResultsRMSML during lead limb crossing was significantly increased in older adults compared to young adults (p < 0.01). There was no significant main effect of visual condition and age group on RMSRML for the three steps. SignificanceThe study results suggest postural lateral instability in older adults with poor balance ability during lead limb crossing. Regardless of age, the peripheral visual information appears to contribute minimally to the maintenance of postural lateral stability at least from two steps before the obstacle, when the participants perceived the surrounding environment and the size of the obstacle while approaching it.

Deep Learning based Object Distance Measurement Method for Binocular Stereo Vision Blind Area

Visual field occlusion is one of the causes of urban traffic accidents in the process of reversing. In order to meet the requirements of vehicle safety and intelligence, a method of target distance measurement based on deep learning and binocular vision is proposed. The method first establishes binocular stereo vision model and calibrates intrinsic extrinsic and extrinsic parameters, uses Faster R-CNN algorithm to identify and locate obstacle objects in the image, then substitutes the obtained matching points into a calibrated binocular stereo model for spatial coordinates of the target object. Finally, the obstacle distance is calculated by the formula. In different positions, take pictures of obstacles from different angles to conduct physical tests. Experimental results show that this method can effectively achieve obstacle object identification and positioning, and improve the adverse effect of visual field blindness on driving safety.

Influence of vision conditions on postural control in right and left hemispheric lesions

Objective Postural regulation is a prerequisite of executing functional activities in various environments. The integration of sensory inputs is weighted differently according to the situation and the required motor strategies. Stroke impairs postural regulation and production of motor strategies, and visual inputs might have different influence depending on the side of the lesion. The main objective of this study was to determine whether side of hemispheric lesion influences the effects of visual inputs on postural regulation in the medial-lateral and anterior-posterior axes when self-imposed disturbances occur in the seated position. Material/Patients and methods We assessed 22 chronic stroke participants (12 with right and 10 with left side lesions; > 6 months) who had a single hemispheric stroke. Participants were asked to maintain their balance in a sitting position on a seesaw placed on a force platform that recorded at 40 Hz. Four conditions were tested: eyes open and closed; with alteration of the right and left visual field using goggles. The area, length and speed of the Centre of Pression (COP) in the medial-lateral and anterior-posterior axes were analyzed with two-way ANOVAs to assess the effects of vision and group. Results The effects of the occlusion of visual field on postural control differed depending on the side of the lesion. In both the medial-lateral and anterior-posterior axes, the left visual field occlusion perturbed stability in the participants with the right lesion while the right visual field occlusion perturbed stability in the participants with the left lesion. In addition, the visual effect differed for these two groups of patients with greater destabilization on the medial-lateral axis for those having a right side lesion. Discussion/Conclusion Our findings emphasized the dominant role of the right hemisphere on postural control under vision conditions, particularly in the medial-lateral axis where greater instability was observed in people with a right hemispheric lesion.

Effects of acute peripheral/central visual field loss on standing balance.

Vision impairments such as age-related macular degeneration (AMD) and glaucoma are among the top risk factors for geriatric falls and falls-related injuries. AMD and glaucoma lead to loss of the central and peripheral visual fields, respectively. This study utilized a custom contact lens model to occlude the peripheral or central visual fields in healthy adults, offering a novel within-subject approach to improve our understanding of the etiology of balance impairments that may lead to an increased fall risk in patients with visual field loss. Two dynamic posturography tests, including an adapted version of the Sensory Organization Test and a virtual reality environment with the visual scene moving sinusoidally, were used to evaluate standing balance. Balance stability was quantified by displacement and time-normalized path length of the center of pressure. Nine young and eleven older healthy adults wore visual field occluding contact lenses during posturography assessments to compare the effects of acute central and peripheral visual field occlusion. The results found that visual field occlusion had greater impact on older adults than young adults, specifically when proprioceptive cues are unreliable. Furthermore, the results suggest that both central and peripheral visions are important in postural control; however, peripheral vision may be more sensitive to movement in the environment.

The effect of trial frames on adaptive gait

PurposeResearch investigating how vision affects adaptive gait typically tests participants whilst wearing their own spectacles or whilst wearing trial case lenses mounted in a trial frame. Trial frames are temporary frames allowing different lenses to be inserted, permitting different visual conditions to be simulated. Trial frames occlude part of the wearer's peripheral visual field. The current study investigated how use of trial frames affects adaptive gait. MethodsFifteen participants (age 25±5 years) with normal uncorrected vision negotiated a single floor based obstacle habitually (not wearing a trial frame) or wearing trial frames which occluded part of the lower visual field (half-eye) or circumferential peripheral visual field (full aperture). No lenses were used in the trial frames. Analysis assessed visual field occlusion and the kinematics of obstacle crossing. ResultsVisual field was reduced wearing either trial frame. Compared to the habitual condition, participants wearing either type of trial frame lifted their foot significantly higher over the obstacle and increased the time taken to step over the obstacle; a result of uncertainty regarding the precise location (height) of the obstacle due to the occlusion of visual information from the inferior visual field. There were no differences in obstacle crossing between trial frame conditions. ConclusionsWearing either full or half eye trial frames can in itself influence adaptive gait. Whilst consideration needs to be given to the visual correction that participants wear during gait research, the method of mounting these lenses also requires consideration.

Simulated Visual Field Loss Does Not Alter Turning Coordination in Healthy Young Adults

ABSTRACTTurning, while walking, is an important component of adaptive locomotion. Current hypotheses regarding the motor control of body segment coordination during turning suggest heavy influence of visual information. The authors aimed to examine whether visual field impairment (central loss or peripheral loss) affects body segment coordination during walking turns in healthy young adults. No significant differences in the onset time of segments or intersegment coordination were observed because of visual field occlusion. These results suggest that healthy young adults can use visual information obtained from central and peripheral visual fields interchangeably, pointing to flexibility of visuomotor control in healthy young adults. Further study in populations with chronic visual impairment and those with turning difficulties are warranted.

Utility of Peripheral Visual Cues in Planning and Controlling Adaptive Gait

To determine the relative importance to adaptive locomotion of peripheral visual cues provided by different parts of the visual field. Twelve subjects completed obstacle crossing trials while wearing goggles that provided four visual conditions: upper visual field occlusion, lower visual field occlusion (LO), circumferential peripheral visual field occlusion (CPO), and full vision. The obstacle was either positioned as a lone structure or within a doorframe. Given that subjects completed the task safely without cues from the lower or peripheral visual field, this suggests that subjects used exteroceptive information provided in a feed-forward manner under these conditions. LO and CPO led to increased foot placement distance from the obstacle and to increased toe clearance over the obstacle with a reduced crossing-walking velocity. The increased variability of dependent measures under LO and CPO suggests that exproprioceptive information from the peripheral visual field is generally used to provide online control of lower limbs. The presence of the doorframe facilitated lead-foot placement under LO by providing exproprioceptive cues in the upper visual field. However, under CPO conditions, the doorframe led to a further reduction in crossing velocity and increase in trail-foot horizontal distance and lead-toe clearance, which may have been because of concerns about hitting the doorframe with the head and/or upper body. Our findings suggest that exteroceptive cues are provided by the central visual field and are used in a feed-forward manner to plan the gait adaptations required to safely negotiate an obstacle, whereas exproprioceptive information is provided by the peripheral visual field and used online to "fine tune" adaptive gait. The loss of the upper and lower peripheral visual fields together had a greater effect on adaptive gait compared with the loss of the lower visual field alone, likely because of the absence of lamellar flow visual cues used to control egomotion.

Handedness of children determines preferential facial and eye movements related to hemispheric specialization

Despite repeated demonstrations of asymmetries in several brain functions, the biological bases of such asymmetries have remained obscure. To investigate development of lateralized facial and eye movements evoked by hemispheric stimulation in right-handed and left-handed children. Fifty children were tested according to handedness by means of four tests: I. Mono-syllabic non-sense words, II. Tri-syllabic sense words, III. Visual field occlusion by black wall, and presentation of geometric objects to both hands separately, IV. Left eye and the temporal half visual field of the right eye occlusion with special goggles, afterwards asking children to assemble a three-piece puzzle; same tasks were performed contra-laterally. Right-handed children showed higher percentage of eye movements to right side when stimulated by tri-syllabic words, while left-handed children shown higher percentages of eyes movements to left side when stimulated by the same type of words. Left-handed children spent more time in recognizing non-sense mono-syllabic words. Hand laterality correlated with tri-syllabic word recognition performance. Age contributed to laterality development in nearly all cases, except in second test. Eye and facial movements were found to be related to left- and right-hand preference and specialization for language development, as well as visual, haptic perception and recognition in an age-dependent fashion in a complex process.