Binocular Asymmetry Research Articles

Quantitative evaluation of retinal and choroidal vascularity and retrobulbar blood flow in patients with myopic anisometropia by CDI and OCTA

AimsTo investigate the association between the myopic severity and retinal microvascular density, choroidal vascularity and retrobulbar blood flow in adult anisomyopes.MethodsThis study comprised 90 eyes of 45 myopic anisomyopes who...

Blind stereoscopic 3D image quality assessment via analysis of naturalness, structure, and binocular asymmetry

Over recent years, stereoscopic three dimensional (S3D) images have grown explosively and received increasing attention. Quality assessment, as the fundamental problem, plays an important role in promoting the prevalence of S3D images as well as the associated products. In this paper, an effective blind quality assessment method of S3D images is proposed via analysis of naturalness, structure, and binocular asymmetry. To be specific, given that natural images obey certain regular statistical properties, natural scene statistic (NSS) features of left and right views are first extracted to quantify the naturalness. Second, by considering binocular visual characteristics, statistical features are extracted from a created cyclopean map. Moreover, gray level co-occurrence matrix (GLCM) is utilized to capture quality-sensitive features from the cyclopean phase map. Third, to quantify the asymmetric distortion, a simple but effective measurement is utilized, i.e., calculating the similarity between left and right views as well as statistical features of their difference map. Finally, all extracted quality-sensitive features are combined, and trained together with the subjective ratings to form a regression model using support vector regression (SVR). Experimental results on four publicly available databases (two symmetrically distorted databases and two asymmetrically distorted databases) demonstrate that the proposed method is superior to several mainstream image quality assessment (IQA) metrics.

Effect of body position on the pathogenesis of asymmetric primary open angle glaucoma.

To explore the pathogenesis of asymmetric primary open angle glaucoma (POAG) in both eyes by comparing the intraocular pressure (IOP) of patients who sleep in different positions and to investigate the relationship between IOP variations and sleep positions. One hundred and thirty-one patients with asymmetric POAG and forty-six healthy volunteers were enrolled. All participants completed a questionnaire that provided information about their sleep laterality. The cup disc ratio (C/D) and visual field defect established binocular asymmetry. The IOP of both eyes was measured using iCare parameters after the patients were asked to change body position. The "worse" and "better" eyes were identified according to the diagnosis, whereas the "dependent" and "independent" eyes were defined according to the lateral position. No significant difference in sleep laterality was observed between healthy people and patients with POAG (F=3.195, P=0.362). Among the enrolled patients, the IOP of the dependent eye was always greater than that of the independent eye in the lateral position (P<0.05). In the patients with binocular asymmetric POAG, the questionnaire clearly showed that 85.7% of left side preferences were found their left eyes to be the worse eyes and the right eyes of 71.4% patients with a right side preference were the more serious. When the asymmetric C/D ratio was greater than or equal to 0.2, the worse eye of patients with POAG and a preferred sleeping position was the dependent eye (χ2 =16.762, P=0.001). A higher IOP was measured in the dependent eye in the lateral position. The long-term tendency to choose a lateral sleeping position might lead the dependent eye to manifest more severe symptoms than the independent eye. Thus, the lateral sleeping position might be one cause of asymmetric POAG.

Multiview Stereoscopic Video Hole Filling Considering Spatiotemporal Consistency and Binocular Symmetry for Synthesized 3D Video

This paper proposes a new hole-filling method with spatiotemporal consistency and binocular symmetry for synthesized 3D videos in view extrapolation. Disocclusion regions in the synthesized views at virtual viewpoints result in regions with missing content. These regions will be referred to as hole regions. To provide the high-quality synthesized 3D videos via 3D display, the hole regions need to be filled considering the characteristics of human visual perception. From the perceptual point of view, binocular asymmetry between synthesized left- and right-eye videos (i.e., stereo pair video) is one of the most important factors that induce visual discomfort in stereoscopic viewing. In addition, binocular symmetry without temporal consistency between temporally neighboring frames could cause visual discomfort by annoying flickering artifacts. In this paper, to maintain the spatiotemporal consistency and binocular symmetry in synthesized 3D videos at multiple virtual viewpoints, we propose a global optimization-based hole-filling method using the information from the already filled adjacent view and previous frame. Furthermore, to reduce the computational cost of the global optimization, we propose a label propagation method, which propagates reliable labels used in the adjacent view and previous frame to the target image to be filled. The performance of the proposed method has been evaluated by objective assessments of 3D image quality, temporal consistency, and computational efficiency. In addition, subjective assessment is conducted for measuring the visual comfort and overall quality. The experimental results proved that the proposed method provides hole filling results with spatiotemporal consistency and binocular symmetry.

Clinical analysis on angle-closure glaucoma with binocular asymmetry of anterior chamber depth

Objective To analyze clinical features and treatment for angle-closure glaucoma with binocular asymmetry of anterior chamber depth. Methods Twenty-one eyes of 21 cases with binocular asymmetry of anterior chamber depth were analyzed retrospectively (relaxation of ciliary zonule in 2 cases; subluxation of lens in 18 cases; glaucoma secondary to retinal vascular occlusion in 1 case). All cases were characterized by high intraocular pressure, shallow anterior chamber, anterior chamber angle closure, and similar to primary angle closure glaucoma. Ectopia lentis occurred in 20 cases. All cases underwent YAG laser peripheral iridotomy, trabeculectomy or lens extraction, even combined with anterior vitrectomy. The posterior chamber lenses were implanted into the capsular bag or suspended according to the different instances of relaxation of ciliary zonule. Secondary glaucoma was treated with intravitreal injection of Conbercept. Results After operation, all cases obtained normal intraocular pressure and visual acuity increased to 0.12-0.8. Conclusion It is very important to differentiate the patients of glaucoma due to binocular asymmetry of anterior chamber depth from primary angle-closure glaucoma. Good surgical efficacy can be obtained via different types of operations according to different situations of diseases. Key words: Zonule, len, relaxation; Glaucoma, secondary; Retinal vascular occlusion; Anterior chamber depth

Critical Binocular Asymmetry Measure for the Perceptual Quality Assessment of Synthesized Stereo 3D Images in View Synthesis

In human vision, excessive binocular asymmetry between the left- and right-eye images can be very problematic to perceive single binocular vision (causing visual discomfort) in the viewing of stereoscopic images. In this paper, we propose a critical binocular asymmetry (CBA) measure for objectively assessing the perceptual quality of the synthesized stereo 3D images generated through a depth-image-based rendering (DIBR) process. The proposed method detects critical regions that are likely to induce excessive binocular asymmetry. In particular, this paper considers view extrapolation since it introduces much more artifacts due to the lack of data. We measure structural similarity on the critical regions between the left and right images to quantify the perceptual effects of binocular asymmetry. The effectiveness of the proposed quality measure has been successfully evaluated by subjective assessment experiments using various types of synthesized stereoscopic images generated by four different DIBR-based view synthesis algorithms. We demonstrate the validity of the proposed quality measure by the comparison of subjective ratings and existing objective methods. Experimental results show that the combined use of the proposed binocular asymmetry measure and existing quality measures substantially improves the performance of the quality measures by explicitly considering the perceptual effects of CBA.

Binocular asymmetry in amblyopia

Binocular asymmetry in amblyopia

Binocular asymmetry in amblyopia

Binocular asymmetry in amblyopia

Rebalancing binocular vision in amblyopia

Humans with amblyopia have an asymmetry in binocular vision: neural signals from the amblyopic eye are suppressed in the cortex by the fellow eye. The purpose of this study was to develop new models and methods for rebalancing this asymmetric binocular vision by manipulating the contrast and luminance in the two eyes. We measured the perceived phase of a cyclopean sinewave by asking normal and amblyopic observers to indicate the apparent location (phase) of the dark trough in the horizontal cyclopean sine wave relative to a black horizontal reference line, and used the same stimuli to measure perceived contrast by matching the binocular combined contrast to a standard contrast presented to one eye. We varied both the relative contrast and luminance of the two eyes' inputs, in order to rebalance the asymmetric binocular vision. Amblyopic binocular vision becomes more and more asymmetric the higher the stimulus contrast or spatial frequency. Reanalysing our previous data, we found that, at a given spatial frequency, the binocular asymmetry could be described by a log-linear formula with two parameters, one for the maximum asymmetry and one for the rate at which the binocular system becomes asymmetric as the contrast increases. Our new data demonstrates that reducing the dominant eye's mean luminance reduces its suppression of the non-dominant eye, and therefore rebalances the asymmetric binocular vision. While the binocular asymmetry in amblyopic vision can be rebalanced by manipulating the relative contrast or luminance of the two eyes at a given spatial frequency and contrast, it is very difficult or even impossible to rebalance the asymmetry for all visual conditions. Nonetheless, wearing a neutral density filter before the dominant eye (or increasing the mean luminance in the non-dominant eye) may be more beneficial than the traditional method of patching the dominant eye for treating amblyopia.

Effect of Stimulus Width on the Perceived Visual Discomfort in Viewing Stereoscopic 3-D-TV

To address the issues of viewing safety in stereoscopic three-dimensional television, it is important to investigate determinants of visual discomfort in viewing stereoscopic images. In stereoscopic viewing, it is well known that visual discomfort can be induced by excessive binocular disparity, fast changes in binocular disparity, and binocular asymmetry. However, subjective sensation of visual discomfort could also be substantially different depending on other characteristics of visual stimulus given the complexity of the visual system. From previous studies that have investigated the relation between stimulus characteristics and binocular fusion limit, we speculate that stimulus width (i.e., object width in the stereoscopic scene) can also affect the perceived visual discomfort of stereoscopic images. This paper investigates the effect of stimulus width on visual discomfort by measuring subjective visual discomfort and binocular fusion time. Experimental results show that smaller stimulus width could induce more visual discomfort and increase binocular fusion time.

Clinical and ocular motor analysis of congenital nystagmus in infancy

Purpose: The purpose of this study was to identify the clinical and ocular motility characteristics of congenital nystagmus and to establish the range of waveforms present in infancy. Background: The clinical condition of congenital nystagmus usually begins in infancy and may or may not be associated with visual sensory system abnormalities. Little is known about its specific waveforms in infancy or their relationship to the developing visual system. Methods: Forty-three infants with involuntary ocular oscillations typical of congenital nystagmus were included in this analysis. They were evaluated both clinically and with motility recordings. Eye movement analysis was performed off line from both chart recordings and computer analysis of digitized data. Variables analyzed included age, sex, vision, ocular abnormalities, head position, null-zone or neutral-zone characteristics, symmetry, conjugacy, waveforms, frequencies, foveation times, and responses to convergence and to monocular cover. Results: Patient ages ranged from 3 to 18 months (average, 9.2 months). Seventeen patients (40%) had abnormal vision, 3 had a positive family history of nystagmus, 11 had strabismus, 16 (37%) had a head posture, 26 (60%) had null and neutral positions, 14 (33%) had binocular asymmetry, and all were horizontally conjugate. Average binocular frequency was 2.8 Hz, and average monocular frequency was 4.6 Hz. The waveforms were both jerk and pendular; average foveation periods in patients with normal vision were more than twice as long as those in patients with abnormal vision. Conclusions: Common clinical characteristics and eye-movement waveforms of congenital nystagmus begin in infancy, and waveform analysis at this time helps with both diagnosis and visual status. (J AAPOS 1999;3:70-9)

On the "cyclopean eye": saccadic asymmetry and the reliability of perceived straight-ahead.

If two targets are both on the visual axis of one eye or the other, and binocular fixation is shifted from the farther one to the nearer, the aligned eye consistently makes an initial, seemingly pointless saccade in a temporal direction. The size of those saccades typically differs markedly, depending on whether the targets are aligned with the observer's dominant or non-dominant eye. Pickwell [(1972) Vision Research, 12, 1499-1507] proposed that this binocular asymmetry in oculomotor performance reflects a subject-specific lateral displacement of the egocenter (the "binoculus" of Hering, which has traditionally been assumed to be on the midline). An empirical test of Pickwell's widely endorsed hypothesis has now been conducted and the proposal has been found wanting. In an otherwise darkened room, subjects were required repeatedly to set a small light to a perceived straight-ahead location in the horizontal plane, first for a target at 300 cm distance and then for one at 30 cm. Extrapolation of a line that connects the two averages of those settings to the inter-ocular axis provides an estimate of the subjective egocenter to which visual directions are referred. Contrary to Pickwell's proposal, those locations of the inferred egocenter were usually quite near the midline, and were completely uncorrelated with same-subject data on the extent of saccadic asymmetry at the onset of asymmetrical convergence. The data on perceived straight-ahead underlying this result indicate the availability of extraretinal information about eye orientation that is quite precise at a given moment (median standard deviation of 47 min arc) but conspicuously non-stationary over several-minute intervals (monotonic drifts in sequential settings being very common).

Binocular configurations of a night-flight head-mounted display

Visual configurations for a head-mounted display (HMD) are evaluated with binocular asymmetry as the defining characteristic. With such a configuration the optimum compromise between binocular rivalry, weight and usefulness of see-through at night is sought. A dichoptic area of interest and the addition of a window-frame are shown to be simple and useful aspects of a binocular asymmetric HMD configuration. The dichoptic area of interest combines a large, low-resolution image in one eye with a small, high-resolution image in the other. A window-frame acts as a strong fusion lock and improves the visual quality of the binocular image for some configurations.

The light that leaks: Brückner and the red reflex

The Brückner test utilizes the ophthalmoscope to assess symmetry of binocular fixation by qualitative comparison of the red reflexes. Accurate fixation by the patient's eye on the ophthalmoscope light causes darkening of the red reflex, previously believed due to macular pigmentation. By desgning and experimenting with a beamsplitter ophthalmoscope, we have demonstrated that if the patient's fovea is not exactly conjugate to the light source, light from the retina spills past the light source at the ophthalmoscope mirror into the examiner's eye, creating the red reflex. Therefore, binocular asymmetry of this conjugate relationship, whether due to anisometropia or strabismus, creates asymmetrical red reflexes. Understanding this principle of conjugacy is critical to optimal utilization of the red reflex in routine clinical examination as well as in microsurgery.