Binocular Stereopsis Research Articles

Measurement of paracentral stereopsis using a new method with the binocular open perimeter imovifa® in normal adults.

No method to quantitatively evaluate stereopsis within the 15º visual field has been clinically established. We developed a program to measure paracentral stereopsis and evaluated its feasibility in visually normal participants. Experimental investigation METHODS: Ten visually normal volunteers with stereopsis of 60 arcseconds or better were included. The Stereo Eccentricity Analysis (SEA) program for stereopsis measurement across the visual field was integrated into the binocular visual field analyzer imovifa®. Subjects with established binocular stereopsis detected a stereoscopic circular target presented with crossed disparity on random dots at the fovea, 3°, 5°, 10°, and 15° on the 45°, 135°, 225°, and 315° meridians. The subjects performed two tasks for measurement in the periphery: a detection task by pressing the response button when the circular target was perceived and a localization task by tilting a joystick to indicate in which quadrant the circular target was perceived. The duration of the target presentation was 500 ms. The stereo thresholds at 0º and 3° did not significantly differ. The thresholds at 10º and 15º were significantly higher than at 0° (P < 0.01). While no inter-individual threshold difference was observed at the fovea, the difference was large at 15°. The stereo thresholds for the detection and localization tasks also did not differ significantly. With the SEA program, paracentral stereopsis can be measured and the stereo threshold increases with eccentricity. The SEA program appears to be a feasible clinical method to evaluate paracentral stereopsis.

Neonatal Macular Hemorrhage in a Term Healthy Infant: 18-Year Follow-up.

Unobstructed binocular vision is required during the critical period of vision development to obtain optimal visual acuity in each eye and binocular stereopsis. In this article, we report 18-year follow-up of a full-term, otherwise healthy infant noted to have dense premacular hemorrhage occluding the visual axis in the left eye on retinal imaging performed 48 hours after birth. Serial examinations by the retina service were performed weekly for 10 weeks as the hemorrhage resolved spontaneously. Shortly thereafter, visual acuity revealed fixation was present, but the mother noted intermittent left eye esodeviation. At 90 days of life, the infant was seen by pediatric ophthalmology and started on 1 to 2 hours patching of the right eye daily for the esotropia, which was maintained through 24 months. At 18 years of age, the patient had orthophoria alignment, no spectacle correction, vision of 20/20 in the right eye and 20/25 in the left eye, and normal binocularity and stereopsis. Intermittent esodeviation on the left eye was observed when the patient was fatigued. Early identification of a visual axis occlusion led to prompt referral for the esotropia and initiation of patching therapy. This patient ultimately achieved a very favorable visual functional outcome that may not have been possible without early detection and management. This case report describes the longest-term published follow-up of a neonatal macular hemorrhage. [Ophthalmic Surg Lasers Imaging Retina 2024;55:354-357.].

Six-month binocular stereopsis recovery and its influencing factors in children with intermittent exotropia

ObjectiveTo investigate the recovery of binocular stereopsis recovery and its influencing factors in children with intermittent exotropia after successful correction of eye position.MethodsProspective clinical study. A total of 178 patients, aged 9 ∼ 14 (10.8 ± 1.7) years, who were successfully corrected after intermittent exotropia surgery at the Beijing Tongren Hospital Affiliated to Capital Medical University from October 2023 to September 2023 were collected, the follow-up duration was six-month or longer. Paired t test, Pearson correlation analysis and multivariable linear regression analysis were used to probe preoperative clinical features that may predict the stereopsis six months after surgery.ResultsSix months after surgery, the angle of deviation of the patients met the orthotopic standard, and there was significant difference compared with that before surgery (distant: -2.7△±3.2△ vs. -30.5△±8.4△, t=-25.3, P < 0.001. Near:-3.7△±4.1△ vs. -33.7△±8.0△, t=-26.1, P < 0.001). Distant stereopsis (3.0 ± 0.6 vs. 3.9 ± 0.4, t = 4.9, P < 0.05) and near stereopsis (2.3 ± 0.5 vs. 2.6 ± 0.4, t = 3.8, P < 0.05) were both significantly improved compared with that of before surgery. 17% and 22% patients rebuilt normal distant stereopsis and normal near stereopsis, respectively. Preoperative distant stereopsis (r=-0.26, P = 0.004) and near stereopsis (r=-0.23, P = 0.011) was significantly negatively correlated with convergence reserve. Multivariable analysis showed that patients’ age (β = 0.003, p = 0.037), anisometropia (β = 0.015, p = 0.043), and preoperative distant stereopsis (β = 0.456, p < 0.001) were significantly associated with postoperative distant stereopsis. Patients’ age (β = 0.005, p = 0.044), anisometropia (β = 0.127, p = 0.034), angle of deviation (β=-0.230, p = 0.020), and preoperative near stereopsis (β = 0.136, p < 0.001) were significantly associated with postoperative near stereopsis.ConclusionIXT patients could get eye position fixed after surgery, about 20% patients benefited from stereopsis improvement. Patient’s age, binocular anisometropia, angle of deviation and preoperative stereopsis were independent factors influencing postoperative stereopsis.

Evaluation of visual plasticity in patients with refractive amblyopia treated using a visual perceptual learning system.

Amblyopia is a neurological deficit in binocular vision that affects 3% of the population and is the result of disruptions in early visual development. In this study, we used a visual perceptual learning system for the short-term treatment of children with ametropic amblyopia and evaluated the clinical efficacy of this system in terms of visual plasticity. We conducted a retrospective analysis of the clinical data of 114 children (228 eyes) with refractive amblyopia, who were aged 6.51 ± 1.51 years. Prior to the treatment, we evaluated all children with amblyopia using the visual information processing test. We determined the type of amblyopic defect according to the type of amblyopia, corrected visual acuity, and advanced visual function test results. Based on the type of defect, each child with amblyopia was given short-term visual perception training for 10 days. Finally, we compared the results of visual acuity and visual information processing tests before and after the treatment. The best-corrected visual acuity of patients was better after 10 days of visual training than that before training (P< 0.05). The perceptual eye position after training improved with statistically significant differences in horizontal and vertical perceptual eye position (both P< 0.05) compared to that before training. The number of amblyopic children without suppression in both eyes was 81 cases (71.1%) after training which was higher than that (65 cases, or 57.0%) before training, with a statistically significant difference (P< 0.05). Binocular fine stereopsis and dynamic stereopsis improved after training with a statistically significant difference (both P< 0.05). In this study, it was found that patients with amblyopia showed visual plasticity. Moreover, continuous visual perceptual learning improved the best-corrected visual acuity and recovered stereopsis in children with refractive amblyopia.

Evaluation of the impact of binocular versus monocular cataract surgery using Catquest-9SF: a randomized controlled trial.

This prospective, randomized, unmasked, clinical trial aimed to report the visual outcomes of cataract surgery on both eyes versus cataract surgery on one eye in Brazilian patients. This study included patients with bilateral cataracts and binocular visual acuity worse than or equal to 0.3 logarithm of the minimum angle of resolution. The patients were randomly assigned to undergo surgery on one (Control Group) or both eyes (one eye at a time; Intervention Group). Postoperatively, self-reported visual function using Catquest-9SF (primary outcome measure), binocular visual acuity, stereopsis, and ocular dominance (secondary outcome measures) were compared. A total of 151 patients (77 and 148 eyes in the Control and Intervention Groups, respectively) completed the follow-up. Patients who underwent surgery on both eyes exhibited significantly better self-reported visual function (p=0.036) and stereopsis (p=0.026) than those who underwent surgery on one eye. Binocular visual acuity and ocular dominance did not affect the group comparisons. Surgery on both eyes resulted in significantly better self-reported visual function and stereopsis than surgery on one eye.

Clinical Outcomes and Nutritional Status of Children with Intermittent Exotropia Treated with Surgery During the Preschool and Post-School Age

In this study, we compared the clinical outcomes and differences in nutritional status between preschool and post-surgical treatment of intermittent exotropia. We selected 100 children with intermittent exotropia between August 2019 and August 2022 for the study. Among them, 42 children received surgical treatment before school age (4–6 years) and were considered to be in group A, whereas 58 children received surgical treatment after school age (7–12 years) and were considered to be in group B. We found no difference in orthokeratology, overcorrection, or undercorrection rates between the two groups of children before and after surgery (P &gt; 0.05), and the strabismus was lower at 6 and 12 months after surgery than before surgery and lowest at 12 months after surgery (P &lt; 0.05). In addition, the normal rates of visual function, fusion function, and binocular stereopsis were higher in group A than in the control group at 6 and 12 months postoperatively (P &lt; 0.05). The Child Intermittent Exotropia Questionnaire scores were higher in both groups at 12 months postoperatively than at 6 months and were higher in group A than in group B (P &lt; 0.05). Family members of children in group A were more satisfied with the treatment than in group B (P &lt; 0.05), but the difference in albumin, transferrin, and proalbumin before and after surgery was lower in group B than in group A (P &lt; 0.05). It follows that performing intermittent exotropia surgery before school age can more effectively improve the prognosis of children’s binocular visual function, whereas performing intermittent exotropia after school age has less impact on nutritional status.

Improvement of Perceived Depth Degradation by Motion Parallax in Binocular Stereopsis With Left-Right Retinal Image Mismatch

Improvement of Perceived Depth Degradation by Motion Parallax in Binocular Stereopsis With Left-Right Retinal Image Mismatch

The horopter: Old and new.

The horopter's history may partly be responsible for its ambiguous psychophysical definitions and obscured physiological significance. However, the horopter is a useful clinical tool integrating physiological optics and binocular vision. This article aims to help understand how it could come to such different attitudes toward the horopter. After the basic concepts underlying binocular space perception and stereopsis are presented, the horopter's old ideas that influence today's research show their inconsistencies with the conceptualized binocular vision. Two recent geometric theories of the horopter with progressively higher eye model fidelity that resolve the inconsistencies are reviewed. The first theory corrects the 200-year-old Vieth-Müller circle still used as a geometric horopter. The second theory advances Ogle's classical work by modeling empirical horopters as conic sections in the binocular system with the asymmetric eye model that accounts for the observed misalignment of optical components in human eyes. Its extension to iso-disparity conics is discussed.

Visual and haptic cues in processing occlusion.

Although shape is effective in processing occlusion, ambiguities in segmentation can also be addressed using depth discontinuity given visually and haptically. This study elucidates the contribution of visual and haptic cues to depth discontinuity in processing occlusion. A virtual reality experiment was conducted with 15 students as participants. Word stimuli were presented on a head-mounted display for recognition. The central part of the words was masked with a virtual ribbon placed at different depths so that the ribbon appeared as an occlusion. The visual depth cue was either present with binocular stereopsis or absent with monocular presentation. The haptic cue was either missing, provided consecutively, or concurrently, by actively tracing a real off-screen bar edge that was positionally aligned with the ribbon in the virtual space. Recognition performance was compared between depth cue conditions. We found that word recognition was better with the stereoscopic cue but not with the haptic cue, although both cues contributed to greater confidence in depth estimation. The performance was better when the ribbon was at the farther depth plane to appear as a hollow, rather than when it was at the nearer depth plane to cover the word. The results indicate that occlusion is processed in the human brain by visual input only despite the apparent effectiveness of haptic space perception, reflecting a complex set of natural constraints.

Applications and implications for extended reality to improve binocular vision and stereopsis.

Extended reality (XR) devices, including virtual reality (VR), augmented reality (AR), and mixed reality (MR) devices, are immersive technologies that can swap or merge the natural environment with virtual content (e.g., videogames, movies, or other content). Although these devices are widely used for playing videogames and other applications, they have one distinct feature that makes them potentially very useful for the measurement and treatment of binocular vision anomalies-they can deliver different content to the two eyes simultaneously. Indeed, horizontally shifting the images in the two eyes (thereby creating binocular disparity) can provide the user with a compelling percept of depth through stereopsis. Because these devices are stereoscopic, they can also be used as high-tech synoptophores, in which the images to the two eyes differ in contrast, luminance, size, position, and content for measuring and treating binocular anomalies. The inclusion of eye tracking in VR adds an additional dimension to its utility in measuring and treating binocular vision anomalies, as well as other conditions. This paper describes the essential requirements for testing and treating binocular anomalies and reviews current studies in which XR devices have been used to measure and treat binocular vision anomalies.

Temporal synchronization elicits enhancement of binocular vision functions

Integration of information over the CNS is an important neural process that affects our ability to perceive and react to the environment. The visual system is required to continuously integrate information arriving from two different sources (the eyes) to create a coherent percept with high spatiotemporal precision. Although this neural integration of information is assumed to be critical for visual performance, it can be impaired under some pathological or developmental conditions. Here we took advantage of a unique developmental condition, amblyopia ("lazy eye"), which is characterized by an impaired temporal synchronization between the two eyes, to meticulously study the effect of synchronization on the integration of binocular visual information. We measured the eyes' asynchrony and compensated for it (with millisecond temporal resolution) by providing time-shifted stimuli to the eyes. We found that the re-synchronization of the ocular input elicited a significant improvement in visual functions, and binocular functions, such as binocular summation and stereopsis, were regained. This phenomenon was also evident in neurophysiological measures. Our results can shed light on other neural processing aspects and might also have translational relevance for the field of training, rehabilitation, and perceptual learning.

Binocular function and stereopsis in neovascular age-related macular degeneration

Binocular function and stereopsis in neovascular age-related macular degeneration

Ten-Year Outcomes of LASIK for Pediatric Myopic Anisometropia.

To evaluate long-term safety, effectiveness, and stability of unilateral LASIK in pediatric myopic anisometropic amblyopia. This retrospective study included children who received unilateral LASIK for myopic anisometropia of >6 D, after mandatory 6-month occlusion/penalization therapy. They were evaluated at 6 months, 1 year, 2 years and biannually until 10 years. Outcome measures included visual acuity, refraction, ocular alignment, stereopsis, corneal clarity, and corneal topography. 32 patients (16 girls) with mean age of 8.6 ± 2.3 years completed 10 years of follow up after unilateral LASIK. Mean preoperative spherical equivalent refraction (SER) was -10.3D ±2.0D in the affected eye, with anisometropic difference of -9.5D ±1.7D. Mean post-LASIK SER was -1.3D±0.8D (p<0.001). Anisometropia significantly decreased to 0.3D±0.8D, 0.4D±1.0D, and 1.0±2.5D at 6 months, 1 year and 10 years respectively (p<0.001). 11 patients (34%) who had preoperative intermittent exotropia (< 15°) regained orthophoria in all gazes, while 5 of 10 who had constant exotropia with large angle (>30°) required strabismus surgery for ocular alignment. BCVA improved from 0.04±0.6 Decimal at baseline to 0.6 ±0.2 after LASIK and occlusion therapy (p< 0.001). Despite insignificant refractive regression in both eyes, patients have maintained orthophoria, improved stereopsis, clear cornea, and the topography showed no evidence of post-LASIK ectasia. LASIK appears safe, effective, and stable for correcting refractory pediatric myopic anisometropia, in which conventional measures fail or endanger normal visual development. Eliminating anisometropic aniseikonia consequently restores binocular vision and stereopsis which, along with amblyopia therapy, would reverse amblyopia and prevent recurrence.

Comparisons of visual outcomes between bilateral implantation and mix-and-match implantation of three types intraocular lenses.

To compare binocular static visual acuity (SVA), stereopsis, contrast sensitivity (CS) and dynamic visual acuity (DVA) of 5 combinations of bifocal intraocular lenses (IOLs), trifocal IOLs and extended-depth-of-focus (EDOF) IOLs in age-related cataract patients. Two hundred and ninety-two eyes of 146 patients who underwent cataract surgery in the ophthalmology department of the First Affiliated Hospital of Chongqing Medical University were involved. Subgroups included group MM (33patients, bilaterally bifocal IOL, ZMB00), group TT (31patients, bilaterally trifocal IOL, AT LISA tri839MP), group XX (34patients, bilaterally EDOF IOL, ZXR00), group MX (25patients, bifocal IOL, ZMB00 + EDOF IOL, ZXR00) and group TX (23patients, trifocal IOL, AT LISA tri839MP + EDOF IOL, ZXR00). The uncorrected SVAs (UDVA, UIVA and UNVA), uncorrected DVAs (UDDVA, UIDVA and UNDVA), near and distance stereopsis, and CS were assessed 3months postoperatively. Subgroups of TT, XX, MX and TX showed better UIVA than MM (bP = 0.039, 0.021, 0.035 and 0.037, respectively). MX showed better UNVA than MM and TX (bP = 0.031 and 0.013, respectively). MX group had the optimal outcomes of both near and distance stereopsis. In the UDDVA, XX group and MX group showed better outcomes than TX group at 24 fps (frames per second) (bP = 0.019 and 0.023, respectively). XX group and MX group showed optimal outcomes at all speeds of UIDVA (P = 0.001, 0.005, 0.003 and 0.005, respectively). As the speed increased, the XX group and the MX group showed better UNDVA than the MM group and the TT group (P = 0.019, 0.002 and 0.003, respectively). Mix-and-match implantation of bifocal IOLs and EDOF IOLs provides excellent and stable binocular visual outcomes including SVA, stereopsis and DVA in distant and near distances.

Learning to see in depth

Stereopsis provides us with a vivid impression of the depth and distance of objects in our 3- dimensional world. Stereopsis is important for a number of everyday visual tasks, including (but not limited to) reaching and grasping, fine visuo-motor control, and navigating in our world. This review briefly discusses the neural substrate for normal binocular vision and stereopsis and its development in primates; outlines some of the issues and limitations of stereopsis tests and examines some of the factors that limit the typical development of stereopsis and the causes and consequences of stereo-deficiency and stereo-blindness. Finally, we review several approaches to improving or recovering stereopsis in both neurotypical individuals and those with stereo-deficiency and stereo-blindness and outline some emerging strategies for improving stereopsis.

Binocular Vision and Associate Symptoms in Among MSU Students

Binocular depth perception and stereopsis are two important visual perceptual skills that produce healthy binocular vision. In addition, those who perform extended periods of close vision work, such as reading or the prolonged use of computers, are more likely to report the associated symptoms. The aim of the research was to study the relationship between normal binocular vision and associated symptoms based on COVD – QOL questionnaire score. The questionnaire consists of 19 items divided by accommodation, binocularity, orientation, and perception. A score of 20 or more is considered as symptomatic. Majority of 60% (30 students) of students have a total score of 20 or more for the questionnaire. Mostly answered column with the highest score is related to accommodation and binocularity (score of 3 and 4). There is no significant correlation between binocular vision tests and associated symptoms in the sample of MSU students

Effect of the long-term lack of half visual inputs on the white matter microstructure in congenital monocular blindness

Individuals with congenital monocular blindness are born without binocular vision and stereopsis, the effects of which on the brain microstructure are largely unknown. This study aims to investigate the microstructural characteristics of white matter tracts over the whole brain in congenital monocular blindness. We used T1-weighted MRI and diffusion tensor imaging (DTI) to investigate the microstructural characteristics of the brain in 16 patients with unilateral congenital microphthalmia (CM) and 16 matched normally sighted controls. The DTI-derived metrics were assessed using atlas-level analysis with FDR correction and TBSS-level analysis with threshold-free cluster enhancement correction (TFCE). CM exhibited significantly abnormal DTI-derived indices (p < 0.05, q < 0.05 of FDR correction) as follows: 1) declined fractional anisotropy (FA) in the inferior fronto-occipital fasciculus contralateral to the affected eye, bilateral inferior longitudinal fasciculus, while enhanced in the ipsilateral cingulum; 2) increased local diffusion homogeneity in the contralateral corticospinal tract while decreased in the ipsilateral superior longitudinal fasciculus; 3) reduced axial diffusivity (AD) in the body of corpus callosum. Meanwhile, the alteration tendencies of FA, AD, and radial diffusivity (RD) in the forceps major (increased FA and AD, decreased RD) and forceps minor (decreased FA and AD, increased RD) were interestingly opposite. These results reveal extensive microstructural abnormalities of WM ranging from sensory modalities to other cross-modal pathways involving language, execution, memory, emotion, fine movement, and interhemispheric communication as well. This study provides novel evidence of large-scale subcortical involvement subsequent to prolonged loss of half visual inputs, which may be associated with developmental delay and compensatory plasticity.

Association between Anisometropia as Well as Visual Acuity, Aniseikonia, and Stereopsis in the Absence of Strabismus

Objective: The current study aimed to assess the association between the type of anisometropia and its effects on monocular and binocular best-corrected vision acuity (BCVA), aniseikonia, and stereopsis in the absence of strabismus. Methods: In total, 162 individuals with anisometropia and healthy eyes and without a previous history of amblyopia therapy and eye surgery were included in the analysis. According to spherical and cylindrical components and spherical equivalent, they were divided into the spherical hyperopic anisometropia (SHA, n = 31), spherical myopic anisometropia (SMA, n = 45), astigmatic or cylindrical hyperopic anisometropia (CHA, n = 22), and astigmatic or cylindrical myopic anisometropia (CMA, n = 64) groups. Patients without anisometropia (NA, n = 188) were classified under the control group. The effects of anisometropia on monocular and binocular BCVA, aniseikonia, and stereoacuity were examined. Results: The NA group had a significantly lower LogMAR of BCVA of the right eye (RE), left eye (LE), worse eye than the SHA, SMA, CMA, and CHA groups. Moreover, the SMA group had significantly lower LogMAR of BCVA than the CHA group (p 10 arc seconds than the CHA (p 10 arc seconds than the CMA (p 10 arc seconds (r = 0.160; p = 0.041). Conclusion: Worse visual levels of the RE, LE, worse eye, BCVA difference, and lower stereopsis were evidenced in each type of anisometropia defined in this study. Cylindrical hyperopic anisometropia (CHA) resulted in a statically significant worsening VA level and stereopsis than cylindrical myopic (CMA) or spherical myopic anisometropia.

Cortical mechanism of binocular stereopsis: How our brain constructs the 3D world

Cortical mechanism of binocular stereopsis: How our brain constructs the 3D world

Binocular Vision and Stereopsis Across the Animal Kingdom.

Most animals have at least some binocular overlap, i.e., a region of space that is viewed by both eyes. This reduces the overall visual field and raises the problem of combining two views of the world, seen from different vantage points, into a coherent whole. However, binocular vision also offers many potential advantages, including increased ability to see around obstacles and increased contrast sensitivity. One particularly interesting use for binocular vision is comparing information from both eyes to derive information about depth. There are many different ways in which this might be done, but in this review, I refer to them all under the general heading of stereopsis. This review examines the different possible uses of binocular vision and stereopsis and compares what is currently known about the neural basis of stereopsis in different taxa. Studying different animals helps us break free of preconceptions stemming from the way that stereopsis operates in human vision and provides new insights into the different possible forms of stereopsis.