Gaze Angle Research Articles

Effect of Gaze Angle During the Vertical Video Head Impulse Test Across Two Devices in Healthy Adults and Subjects With Vestibular Loss.

To evaluate the effect of gaze angle on vertical vestibulo-ocular reflex (VOR) gain using two different video head impulse (vHIT) devices in healthy adults and subjects with bilateral vestibular loss (BVL). Prospective study. Hospital research laboratory. Twenty-four healthy adults (mean [standard deviation {SD}] age = 32 [4.8]; 23-42; 8 men) and four subjects with previously diagnosed BVL (mean age [SD] = 32 [8.2]; 21-40; 3 men) participated. Vertical canal vHIT was administered with two different devices using three gaze angles (-45 degrees, 0 degree, +45 degrees). These devices have different gain calculation algorithms and different head and gaze angle protocols. Vertical canal gain and presence or absence of reset saccades. A significant stepwise reduction in vHIT gain was noted as gaze moved away from the plane of the canals stimulated (from -45 degrees to 0 degree, to +45 degrees) for both healthy adults and subjects with BVL. vHIT gain was able to separate the two groups using gaze angles -45 degrees and 0 degree. In spite of their differences in gain algorithm and recommended head position and gaze angle, each device was able to appropriately separate healthy adults from subjects with BVL with high sensitivity/specificity.

Look out: an exploratory study assessing how gaze (eye angle and head angle) and gait speed are influenced by surface complexity.

BackgroundMost research investigating the connection between walking and visual behaviour has assessed only eye movements (not head orientation) in respect to locomotion over smooth surfaces in a laboratory. This is unlikely to reflect gaze changes found over the complex surfaces experienced in the real world, especially given that eye and head movements have rarely been assessed simultaneously.Research questionHow does gaze (eye and head) angle and gait speed change when walking over surfaces of different complexity?MethodsIn this exploratory study, we used a mobile eye tracker to monitor eye movements and inertia measurement unit sensors (IMUs) to measure head angle whilst subjects (n = 11) walked over surfaces with different complexities both indoors and outdoors. Gait speed was recorded from ankle IMUs.ResultsOverall, mean gaze angle was lowest over the most complex surface and this surface also elicited the slowest mean gait speed. The head contributed increasingly to the lowering of gaze with increased surface complexity. Less complex surfaces showed no significant difference between gaze and gait behaviour.SignificanceThis study supports previous research showing that increased surface complexity is an important factor in determining gaze and gait behaviour. Moreover, it provides the novel finding that head movements provide important contributions to gaze location. Our future research aims are to further assess the role of the head in determining gaze location during locomotion across a greater range of complex surfaces to determine the key surface characteristics that influence gaze during gait.

Optimizing Alignment Parameters During Craniocervical Stabilization and Fusion: A Technical Note.

Proper craniocervical alignment during craniocervical reduction, stabilization, and fusion optimizes cerebrospinal fluid (CSF) flow through the foramen magnum, establishes the appropriate “gaze angle”, avoids dysphagia and dyspnea, and, most importantly, normalizes the clival-axial angle (CXA) to reduce ventral brainstem compression. To illustrate the metrics of reduction that include CXA, posterior occipital cervical angle, orbital-axial or “gaze angle”, and mandible-axial angle, we present a video illustration of a patient presenting with signs and symptoms of the cervical medullary syndrome along with concordant radiographic findings of craniocervical instability as identified on dynamic imaging and through assessment of the CXA, Harris, and Grabb-Oakes measurements.

The effect of backpack load position on photographic measures of craniovertebral posture in 150 asymptomatic young adults.

Altering the horizontal position of the weight in a backpack will influence the magnitude of the external torque it creates but the effect on posture is unclear. To use photogrammetry to determine if changes in the horizontal position of a fixed backpack weight affect external measures of craniovertebral posture in 150 asymptomatic young adults. A backpack was attached to a steel frame with a bar protruding posteriorly. A fixed load (5% body mass) was placed at three distances along the bar -0 m, 0.20 m, and 0.40 m. Sagittal and frontal plane photogrammetry was used to measure the craniovertebral angle (CVA), upper cervical gaze angle (UCGA) and lateral head tilt angle (LHTA). A comparison was made across unloaded (no backpack) and loaded conditions. There was a significant decrease in the CVA between unloaded and loaded conditions. Changes in the UCGA were small and, while significant, may not have practical importance. There were no differences in the LHTA between the conditions. Changes in the horizontal position of a fixed load affect external measures of craniovertebral posture so consideration needs to be given to not only the weight of a backpack but how the weight is positioned within the backpack.

Cerebellar Rebound Nystagmus Explained as Gaze-Evoked Nystagmus Relative to an Eccentric Set Point: Implications for the Clinical Examination.

A brain stem/cerebellar neural integrator enables stable eccentric gaze. Cerebellar loss-of-function can cause an inability to maintain gaze eccentrically (gaze-evoked nystagmus). Moreover, after returning gaze to straight ahead, the eyes may drift toward the prior eye position (rebound nystagmus). Typically, gaze-evoked nystagmus decays during continuously held eccentric gaze. We hypothesized this adaptive behavior to be prerequisite for rebound nystagmus and thus predicted a correlation between the velocity decay of gaze-evoked nystagmus and the initial velocity of rebound nystagmus. Using video-oculography, eye position was measured in 11 patients with cerebellar degeneration at nine horizontal gaze angles (15° nasal to 25° temporal) before (baseline), during, and after attempted eccentric gaze at ± 30° for 20s. We determined the decrease of slow-phase velocity at eccentric gaze and the slow-phase velocity of the subsequent rebound nystagmus relative to the baseline. During sustained eccentric gaze, eye drift velocity of gaze-evoked nystagmus decreased by 2.40 ± 1.47°/s. Thereafter, a uniform change of initial eye drift velocity relative to the baseline (2.40 ± 1.35°/s) occurred at all gaze eccentricities. The velocity decrease during eccentric gaze and the subsequent uniform change of eye drift were highly correlated (R2 = 0.80, p < 0.001, slope = 1.09). Rebound nystagmus can be explained as gaze-evoked nystagmus relative to a set point (position with least eye drift) away from straight-ahead eye position. To improve detection at the bedside, we suggest testing rebound nystagmus not at straight-ahead eye position but at an eccentric position opposite of prior eccentric gaze (e.g., 10°), ideally using quantitative video-oculography to facilitate diagnosis of cerebellar loss-of-function.

Multiple pedestrian tracking using Siamese random forests and shallow Convolutional Neural Networks

Modern automobiles accidents occur mostly due to inattentive behavior of drivers, which is why driver’s gaze estimation is becoming a critical component in automotive industry. Gaze estimation has introduced many challenges due to the nature of the surrounding environment like changes in illumination, or driver’s head motion, partial face occlusion, or wearing eye decorations. Previous work conducted in this field includes explicit extraction of hand-crafted features such as eye corners and pupil center to be used to estimate gaze, or appearance-based methods like Convolutional Neural Networks which implicitly extracts features from an image and directly map it to the corresponding gaze angle. In this work, a multitask Convolutional Neural Network architecture is proposed to predict subject’s gaze yaw and pitch angles, along with the head pose as an auxiliary task, making the model robust to head pose variations, without needing any complex preprocessing or hand-crafted feature extraction.Then the network’s output is clustered into nine gaze classes relevant in the driving scenario. The model achieves 95.8% accuracy on the test set and 78.2% accuracy in cross-subject testing, proving the model’s generalization capability and robustness to head pose variation.

Foveated holographic near-eye 3D display.

We present a foveated rendering method to accelerate the amplitude-only computer-generated hologram (AO-CGH) calculation in a holographic near-eye 3D display. For a given target image, we compute a high-resolution foveal region and a low-resolution peripheral region with dramatically reduced pixel numbers. Our technique significantly improves the computation speed of the AO-CGH while maintaining the perceived image quality in the fovea. Moreover, to accommodate the eye gaze angle change, we develop an algorithm to laterally shift the foveal image with negligible extra computational cost. Our technique holds great promise in advancing the holographic 3D display in real-time use.

Estimation of mental workload during automobile driving based on eye-movement measurement with a visible light camera

The aim of this study was to investigate the effective parameters of eye movement for estimation of mental workload (MWL) during automobile driving by using a visible light camera. Twelve students (6 males and 6 females) participated in this study. The participants performed a driving task with a driving simulator and a secondary task simultaneously. The N-back task was taken as the secondary task so as to control the MWL. The levels of N-back task were as follows: none, 0-back, 1-back, 2-back, and 3-back. The gaze and head angles and blink frequency were measured with a visible light camera. The eyeball rotation angle was calculated from the gaze and head angle. The sharing rate of head movement, which is the ratio of head movement against the gaze movement, was calculated. The subjective MWL and accuracy of N-back task were also measured. The result showed that the subjective MWL monotonically increased with the increase of the difficulty of N-back task. The effect of the difficulty of N-back task was statistically significant for the standard deviations (SDs) of horizontal and vertical gaze angle, SD of horizontal eyeball rotation angle, sharing rate of head movement in horizontal direction, and blink frequency. The result of logistic regression analysis showed that the SD of horizontal eyeball rotation angle and blink frequency were the most significant parameters to estimate the MWL. The area under the curve (AUC) of receiver operating characteristic (ROC) curve for the regression equation was 0.822; thus, it has relatively high discrimination ability on the MWL.

The Transaxillary Subcutaneous Endoscopic Sternocleidomastoid Muscle Division as an Approach for the Surgical Treatment of Congenital Muscular Torticollis in Children.

Traditionally congenital muscular torticollis is treated with a neck incision which results in a neck scar. The purpose of this study was to evaluate the effectiveness of the transaxillary subcutaneous endoscopic sternocleidomastoid muscle division for the treatment of congenital muscular torticollis. This is a prospective study of 7 children with torticollis treated surgically by the transaxillary endoscopic approach in the department of Pediatric Surgery between 2014 and 2018. The age at operation ranged from 5.5 to 9years, mean 7.3 (SD ± 1.3) years. The mean operation time was 65min. The complete muscular release was successfully completed using the endoscopic approach. There were no major complications. All patients improved in gaze angle, lateral tilt and range of motion. There was no cosmetically unacceptable scar visible at the surgical sites in all patients during follow up. All families were pleased with the cosmetic outcome. The transaxillary subcutaneous endoscopic technique can be applied as a surgical approach for children with muscular torticollis an alternative to traditional open methods. It is a technically feasible procedure in children, provides excellent cosmesis and moreover avoids scarring on the neck.

Misperception of motion in depth originates from an incomplete transformation of retinal signals.

Depth perception requires the use of an internal model of the eye-head geometry to infer distance from binocular retinal images and extraretinal 3D eye-head information, particularly ocular vergence. Similarly, for motion in depth perception, gaze angle is required to correctly interpret the spatial direction of motion from retinal images; however, it is unknown whether the brain can make adequate use of extraretinal version and vergence information to correctly transform binocular retinal motion into 3D spatial coordinates. Here we tested this hypothesis by asking participants to reconstruct the spatial trajectory of an isolated disparity stimulus moving in depth either peri-foveally or peripherally while participants' gaze was oriented at different vergence and version angles. We found large systematic errors in the perceived motion trajectory that reflected an intermediate reference frame between a purely retinal interpretation of binocular retinal motion (not accounting for veridical vergence and version) and the spatially correct motion. We quantify these errors with a 3D reference frame model accounting for target, eye, and head position upon motion percept encoding. This model could capture the behavior well, revealing that participants tended to underestimate their version by up to 17%, overestimate their vergence by up to 22%, and underestimate the overall change in retinal disparity by up to 64%, and that the use of extraretinal information depended on retinal eccentricity. Since such large perceptual errors are not observed in everyday viewing, we suggest that both monocular retinal cues and binocular extraretinal signals are required for accurate real-world motion in depth perception.

Optimum Response Filter Setting for Air Conduction-Induced Ocular Vestibular Evoked Myogenic Potential.

A wide range of normative values of amplitude and latencies can be noticed in the publications on ocular vestibular evoked myogenic potential (oVEMP), possibly because of the inconsistent use of various stimulus and acquisition-related parameters such as response filter, gaze angle, onset polarity of stimulus, etc. One major nonuniform parameter across studies is the response filter. Several band-pass response filters such as 0.5-500, 1-1000, 5-500, 5-800, 10-750, 20-2000, 100-3000, and 200-1000 Hz have been used across published studies, and a wide range of normative values can be noticed. However, there is paucity of literature evidence to show that variations in response filters could cause alterations in oVEMP response. This study aimed to investigate the effects of changes in response filter setting on oVEMP. Normative study using repeated measures research design. Young adults in the age range of 18-35 years (N = 150) and older adults in the age range of 60-70 years (N = 10). Contralateral air conduction oVEMP. Contralateral air conduction oVEMP was obtained from only one ear of all participants. Low-pass filters (LPFs) of 500, 700, 1000, 1500, 2000, and 3000 Hz and high-pass filters (HPFs) of 0.1, 1, 10, and 30 Hz were used in all possible combinations of one LPF and one HPF to create band-pass filters. Latencies, peak-to-peak amplitude, and signal-to-noise ratio (SNR) were obtained for each response and comparison was made between various band-pass filters. In young adults, there was a significant reduction in n1 and p1 latencies with increasing HPF and LPF (p < 0.01) and a significant reduction in peak-to-peak amplitude with increasing HPF (p < 0.008). The peak-to-peak amplitude was significantly not affected by changes in LPF (p > 0.05). In older adults, the response rate was better for 0.1- to 1000-Hz than 1- to 1000-Hz band-pass filters. The optimum band-pass filter is 0.1-1000 Hz for recording oVEMP as it produces the largest amplitude oVEMP without compromising on SNR and causes improved response rate in older adults compared with 1- to 1000-Hz filters. Therefore, clinical recording of oVEMP should use 0.1-1000 Hz for obtaining large amplitude potentials and improving the chances of response detection in clinical population.

Self-denigration and the mixed messages of ‘ugly’ selfies in Instagram

Abstract This paper sets out a new, multimodal account (both visual and verbal analysis) of how self-denigration is conveyed through ‘ugly selfies’ as posted to the photo-sharing site Instagram. Drawing on 226 Instagram posts categorised by the poster themselves with the hashtag #uglyselfie, the visual analysis compared the persons and setting in the selfie, the person’s facial expression (eye brow position, mouth expression), eye gaze and camera angle. The verbal analysis included the self-denigration found in the image caption and the rapport enhancing or threatening responses found in the comments to the image posted by others. Ugly selfies are found to convey various types of self-denigration, including self-deprecation and self-mockery. The difference between self-deprecation and self-mockery are explained by the types of ‘mixed messages’ generated by the images. In self-deprecation, the mixed messages arise from a contrast between the visual image and the verbal caption. In self-mockery, the mixed messages arise from contrasts within the image itself, where visual exaggeration and incongruity lead to a jocular interpretation of the ugly selfie. Although the focus in this paper is on self-denigration and selfie-taking, the analysis of mixed messages can be used to analyse many different forms of politeness strategies and many kinds of images shared with increasing frequency and importance on social media sites.

A Novel Stimulation Paradigm for Obtaining Interfrequency Amplitude Ratio of Ocular Vestibular Evoked Myogenic Potentials.

Purpose Interfrequency amplitude ratio (IFAR), the ratio of amplitude between ocular vestibular evoked myogenic potentials (oVEMPs) for tone bursts of 500 and 1000 Hz, aids in identification of Ménière's disease with high sensitivity and specificity. However, it requires recording of oVEMP for 2 frequencies, which doubles the time of recording. Use of simultaneous recording of responses for both frequencies could potentially bring down testing time. Simultaneous recording might be possible by modifying the oddball paradigm and using a ratio of 1:1 for the 2 frequencies. This might also reduce variation in oVEMP amplitude between frequencies due to changes in gaze angle between the recordings. However, it remains to be explored whether or not the use of modified oddball paradigm to record oVEMP (MoVEMP) will produce comparable responses to conventional sequential recording of oVEMP (CoVEMP) for obtaining IFAR. Hence, the study aimed to compare MoVEMP and CoVEMP on various measures of oVEMP. Method The study included 29 healthy adults in the age range of 18-30 years, 23 of which were used for validation and 6 for finding test-retest reliability. All participants underwent contralateral oVEMP recording using 500- and 1000-Hz tone bursts presented using MoVEMP and CoVEMP paradigms. Results Comparable outcomes on latencies, amplitude, and IFAR were obtained between CoVEMP and MoVEMP. Furthermore, MoVEMP took significantly lesser time per ear and also produced better test-retest reliability than CoVEMP. Conclusion MoVEMP is a quicker and more reliable clinical stimulation paradigm for obtaining IFAR than CoVEMP.

Assessing the Impact of Corneal Refraction and Iris Tissue Non-Planarity on Iris Recognition

Assumptions regarding eye morphology are implicit in iris recognition algorithms. The cornea is assumed to have little to no effect on the view of the iris texture when the eye gaze is non-frontal, the iris is assumed flat, and the eye is assumed to be imaged via an orthographic projection. If these assumptions hold, affine transformations may be used to rectify non-frontally posed images to a frontal view and the rubber sheet model may be accurately used to normalize the iris annulus to a rectangular image. This paper examines how iris recognition performance degrades when the first two assumptions are violated. Using a computer renderable eye model, a data set is created varying the presence of the cornea and a parameterized non-planarity of the iris shape across a large range of eye gaze angles. Matching scores are created using a commercial matcher. When comparing the relative impact of each assumption violation, it is observed that iris non-planarity presents a more significant problem than corneal refractive distortion with regard to iris recognition accuracy in non-frontal images.

Recognition of horizontal gaze motion based on electrooculography using tsugeno fuzzy logic

Electrooculography is a biosignal activity generated from the human’s eyes activity. In this research, the eyes movements (left and right) were recognized by processing the EOG signal. The eyes movements in the horizontal movement were identified from the direction and the magnitude of the gaze angle. The direction of the eyes movements was detected using the polarity of the signal whereas the magnitude of gaze angle was computed using Tsugeno fuzzy method with two approaches, namely area of signal and peak of the signal. The system was able to detect the direction of gaze motion with the accuracy of 100%. The accuracy of the EOG signal in calculating the magnitude of the gaze angle was 93.46% for the right and 89.88% for the left. The number was higher compared to the performance of the peak point with the accuracy of 88.06% for the right and 84.79% for the left. The result in this paper showed that the system was able to detect the direction of eyes movements very well. However, the calculation of the magnitude of eyes movements is still a challenge to be improved in the future.

EOG-Based Gaze Angle Estimation Using a Battery Model of the Eye.

In this work, a novel method to estimate the gaze angles using electrooculographic (EOG) signals is presented. Specifically, this work investigates the use of a battery model of the eye, which relates the recorded EOG potential with the distances between the corresponding electrode and the centre points of the cornea and retina, for gaze angle estimation. Using this method a cross-validated horizontal and vertical gaze angle error of 2.42±0.91° and 2.30±0.50° respectively was obtained across six subjects, demonstrating that the proposed methods and the battery model may be used to estimate the user's ocular pose reliably.

Effect of pupil dilation on off-angle iris recognition

Due to the less constrained setup in standoff iris recognition systems, it is likely to capture nonideal iris images with gaze angle, pupil dilation, reflections, and occlusions. The combined effect of pupil dilation and gaze angle on iris recognition is examined. We first highlight the effects on synthetic images generated with a biometric eye model using a ray-tracing algorithm. Then, we quantify the effects of pupil dilation and gaze angle on the real frontal and off-angle images at different dilation levels. Our experiments reveal that the larger differences in dilation levels and gaze angles between the compared iris images increase the Hamming distance. Even if the linear rubber-sheet normalization helps to minimize the dilation effect in frontal images, it cannot fully eliminate it in off-angle iris images because of not only the pupil dilation and three-dimensional iris texture but also the corneal refraction distortion and limbus occlusion. We also observe that the gaze angle is the main reason for the performance degradation in steeper off-angle images, where the effect of the dilation is limited. In addition, since the iris region in off-angle and dilated iris images is smaller than that in frontal and constricted iris images, their interclass Hamming distance distribution is shifted toward the intraclass distribution, which may increase the false match rate.

Staged cervical osteotomy:a new strategy for correcting ankylosing spondylitis thoracolumbar kyphotic deformity with fused cervical spine

BackgroundIn patients with cervical ankylosis, the chin-brow vertical angle (CBVA) should be taken into consideration. Usually, the correction of sagittal balance is sacrificed to ensure the patient has a horizontal visual field. To our knowledge, a staged osteotomy strategy for ankylosing spondylitis kyphotic deformity with an ankylosed cervical spine has not been reported before. The aim of this study was to describe a new surgical strategy with emphasis on sagittal balance and gaze angle in correction of kyphotic deformity with a rigid cervical spine in ankylosing spondylitis thoracolumbar kyphotic deformity.MethodsA 36-year-old man has severe thoracolumbar kyphosis accompanied with cervical hyperlordosis caused by ankylosing spondylitis. A two-stage surgery planning was managed. For the first stage, an interrupted two-level osteotomy was performed at the thoracolumbar area. After surgery, sagittal imbalance was corrected but the CBVA was − 21.7°. Cervical osteotomy was performed for the second stage. A flexion osteotomy was performed at C7, using anterior-posterior-anterior approaches.ResultsBoth sagittal imbalance and gaze angle of the patient were improved markedly. The osteotomy sites were documented fused. Complications were not observed during and after operation.ConclusionsThe aim of osteotomy for ankylosing spondylitis is to reestablish sagittal balance and improve forward gaze and the visual field. A staged cervical osteotomy is an alternative to reduce cervical lordosis to obtain a normal gaze angle. An anterior-posterior-anterior approach is recommended.

Continuous Driver's Gaze Zone Estimation Using RGB-D Camera.

The driver gaze zone is an indicator of a driver’s attention and plays an important role in the driver’s activity monitoring. Due to the bad initialization of point-cloud transformation, gaze zone systems using RGB-D cameras and ICP (Iterative Closet Points) algorithm do not work well under long-time head motion. In this work, a solution for a continuous driver gaze zone estimation system in real-world driving situations is proposed, combining multi-zone ICP-based head pose tracking and appearance-based gaze estimation. To initiate and update the coarse transformation of ICP, a particle filter with auxiliary sampling is employed for head state tracking, which accelerates the iterative convergence of ICP. Multiple templates for different gaze zone are applied to balance the templates revision of ICP under large head movement. For the RGB information, an appearance-based gaze estimation method with two-stage neighbor selection is utilized, which treats the gaze prediction as the combination of neighbor query (in head pose and eye image feature space) and linear regression (between eye image feature space and gaze angle space). The experimental results show that the proposed method outperforms the baseline methods on gaze estimation, and can provide a stable head pose tracking for driver behavior analysis in real-world driving scenarios.

Differences in eye movement range based on age and gaze direction.

To determine the range of eye movement in normal human subjects and to investigate the effect of age and gaze direction on eye movement. A prospective observational study. We enrolled 261 healthy subjects, 5-91 years of age. Photographs were obtained in the cardinal gaze positions and processed using Photoshop. The processed images were analyzed using the Image J program to measure the angle of eye movement. The angle of eye movement was quantified using a modified limbus test. We measured the angle of eye movement in adduction, abduction, elevation, and depression. The ranges of eye movement were 44.9 ± 7.2° in adduction, 44.2 ± 6.8° in adduction, 27.9 ± 7.6° in elevation, and 47.1 ± 8.0° in depression. The ranges of eye movement in the younger group were higher than that in the older group in adduction, abduction, and elevation (P < 0.001, P = 0.013, and P < 0.001, respectively), except in depression (P = 0.790). There were significant negative correlations between the angles of horizontal and upward gazes and age (R = -0.294 in adduction, R = -0.355 in abduction, and R = -0.506 in elevation, all P < 0.001). However, the angle of downward gaze was not significantly correlated with age (R = 0.017, P = 0.722). The angle of upward gaze most rapidly decreased with age than the angle of other gaze. Unlike the age-related decline of range in horizontal and upward gazes, only downward gaze was not impaired by increasing age. Differences in eye movement range based on gaze direction and their associated aging mechanisms should be considered when assessing eye movements.