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Purpose: Diplopia or heterotropia may occur during physical exercise. However, the influence of exercise on phoria is still unknown. The purpose of this study is to evaluate the effects of a physical activity involving both aerobic and anaerobic exercise on horizontal phoria. Methods: Twenty young adult competitive soccer players (19 males, 1 female) were included and divided equally in two groups by manifest refraction: ametropic (n = 10) and emmetropic (n = 10) subjects. Horizontal phoria was evaluated by a Risley-Maddox rotating prism after a complete dissociation with a 5 Δ prism placed base-up on the non-dominant eye during five different times before (at rest) and after an aerobic-anaerobic workout (immediately, 5 min, 10 min, 25 min). Results: Ametropic subjects had myopia in either eye (median spherical equivalent of −0.63 D [interquartile range from −4.45 to −0.47 D]). Emmetropic subjects were at baseline significantly more esophoric than ametropic subjects (+0.90 ± 1.37 vs. −2.20 ± 2.57 Δ, p = .003). On average emmetropic subjects showed a quadratic course of increasing esophoria, peaking at 10 min (+1.65 ± 2.03 Δ) and then decreasing (+1.25 ± 1.78 Δ), returning to baseline in 50% of cases; while ametropic subjects had a quadratic course of increasing exophoria, peaking at 5 min (−4.00 ± 2.71 Δ) and then decreasing (−2.40 ± 2.80 Δ), returning to baseline in 80% of cases. The variations of phoria induced by physical exercise were significant throughout the time (repeated measures ANOVA p < .001, ηp2  = 0.42). The interaction of time with refractive state on phoria was significant for quadratic term (p = .001, ηp2  = 0.48). Ametropic subjects showed on average higher angles (p = .049, ηp2  = 0.20) and higher variations from baseline phoria (quadratic interaction p = .015, ηp2  = 0.29). Conclusions: Phoria is significantly affected by physical exercise, following a quadratic course of increasing and then decreasing angle. Myopic subjects were on average exophoric, displayed higher angles and variations from baseline, peaked before but recovered at last assessment more than emmetropic subjects. Refractive state may have a major role on predicting the progression; however, whether it is due to manifest refraction itself, accommodation or baseline phoria must be ascertained. Any reliable conclusion cannot be drawn due to small sample size and missing physiological measurements. Fluctuating phoria may provide a basis for decreased stereopsis and altered motion perception, thus affecting sports performance. [ABSTRACT FROM AUTHOR]

Immaturities exist at multiple levels of the developing human visual pathway, starting with immaturities in photon efficiency and spatial sampling in the retina and on through immaturities in the early and later stages of cortical processing. Here, we use steady-state visual evoked potentials (SSVEPs) and controlled visual stimuli to determine the degree to which sensitivity to horizontal retinal disparity is limited by the visibility of the monocular half-images, the ability to encode absolute disparity, or the ability to encode relative disparity. Responses were recorded from male and female human participants at average ages of 5.3 ± 1.6 months, 4.7 ± 1.3 years, and 25.3 ± 6 years. Horizontal disparity sensitivity was measured using planar stereograms that modulated absolute disparity and stereograms portraying disparity gratings that additionally contained relative disparity. Disparity thresholds for absolute disparity changed little over development, but those for relative disparity changed by a factor of ∼10. SSVEPs were also recorded in response to contrast and blur modulation of dynamic random-dot patterns to measure sensitivity to the spatiotemporal content of the monocular half-images. Equating subjective contrast and blur levels between infants, children, and adults based on these measurements did not equate disparity sensitivity. The protracted developmental sequence for horizontal relative disparity coding shown in our measurements is not simply inherited from immaturities in encoding absolute disparity or retinal image contrast but rather reflects immaturities in the computations needed to represent relative disparity that likely involves extrastriate cortical areas where relative disparity is first extracted. [ABSTRACT FROM AUTHOR]

Background. Modern laser vision correction for presbyopia treatment involves non-linear aspheric corneal ablation with the controlled induction of spherical aberration modulation to extend the depth of focus or corneal multifocality induction methods with or without micro-monovision in the non-dominant eye to provide continuous clear vision across distances. Anisometropia and the new higher-order aberrations pattern may be potential risk factors for postoperative stereopsis and contrast sensitivity (CS) deterioration. Purpose. The objective of this systematic review was to assess articles published until 2023 in which CS and/or stereopsis were reported following LASIK presbyopia treatment. Methods. We searched the PubMed, Scopus and Web of Science databases in accordance with the PRISMA 2020 flow diagram. The inclusion criteria specified original papers evaluating the outcomes of laser presbyopia correction as well as the pre- and postoperative assessment of stereopsis and/or CS. The Quality Assessment Tool was applied to assess the risk of bias. Results. We identified 13 studies, including 856 presbyopes (1712 eyes), with preoperative refractive errors from −11.13 D to +5.75 D, with the follow-up range between 3 and 30 months. Either contrast sensitivity improvement or no change following Presbyond® Laser Blended Vision and PresbyMAX® Hybrid was found in the reviewed articles. Some authors reported a significant CS reduction after symmetrical PresbyLASIK, wavefront-guided LASIK and aspheric monovision LASIK. Several studies assessing the effect of Presbyond® LBV on stereopsis showed conflicting results, with the near stereopsis being reduced, unchanged or increased. A significant decrease in stereopsis was reported after aspheric monovision LASIK. Conclusions. The Presbyond® Laser Blended Vision is a safe procedure in terms of the preservation of contrast sensitivity for presbyopia treatment. More studies are needed to elucidate the impact of aspheric corneal ablation methods or other methods inducing corneal multifocality with or without micro-monovision on stereopsis and contrast sensitivity. [ABSTRACT FROM AUTHOR]

Purpose: Stereoscopic immersive virtual reality (SIVR) is a technology that fully immerses the user in a digital environment and permits the perception of two different three-dimensional images of a digital object with each of the two eyes. We conducted a literature review to explore to what extent SIVR can significantly contribute to anatomy education. Methods: We searched PubMed, Scopus, ERIC, and the Cochrane Library for papers investigating the outcomes (effectiveness, perceptions about effectiveness, and side effects) of implementing SIVR in anatomy education. Results: Eight articles were included. Six examined the effectiveness of the educational intervention, while two papers explored only participants’ perceptions. Those perceptions were positive, but there was a considerably higher frequency of side effects compared with other methods. SSIVR was not significantly more effective than non-stereoscopic delivery, mainly when the users interacted with the virtual environment. Conclusion: Using SIVR in anatomy education has led to positive participants’ perceptions and notable side effects, while its effectiveness has not been proven higher than non-stereoscopic images, mainly when the users interacted with the digital objects. Future research will further clarify to what extent this technology should be implemented in anatomy education to minimize side effects and maximize its educational potential. [ABSTRACT FROM AUTHOR]

Background: A new, portable computerized distance vision testing (screen plus remote) system called VisionKeys has been developed by the missions equipment developer EyeMobil so we validated it compared to conventional research testing devices. Methods: Using a standardized protocol of surround HOTV optotype presentation, the VisionKeys was compared to M&S for patched monocular distance visual acuity. A different VisionKeys function with anaglyph spectacle distance stereopsis was compared to near stereo on Titmus circles with Polaroid goggles and PDI Check on an autostereoscopic screen. Raw scores were converted to logarithm and compared with non-parametric and Bland Altman tests. Results: We recruited 145 ethnically diverse patients with range of acuity − 0.4 to 2.6 (NLP) logMAR from a pediatric eye and adult strabismus practice showing median logMAR acuity of 0.0 with VisionKeys significantly finer resolution than 0.1 for M&S (Mann–Whitney z=2.6, p=0.01, n=290). VisionKeys acuity correlated very well with M&S and children under age 7 scored coarser than teens and young adults. Median distance log arc seconds stereo on VisionKeys (2.00) differed from near Titmus circles (1.78) and PDI Check (1.89, Kruskal–Wallis X2(2)=9.8, p=0.007) however they all correlated well by Bland Altman. Conclusion: The new, portable VisionKeys system gives valid distance visual acuity with slightly finer estimate compared to M&S and the distance stereo compared well with near Titmus and PDI Check. As such, it should be valuable for testing children and adults in remote locations. [ABSTRACT FROM AUTHOR]

AIM: To investigate the underlying factors by establishing a new paradigm for assessing control ability under stereopsis testing conditions. METHODS: This was a prospective observational study. We evaluated the control ability of intermittent exotropia (IXT) patients in three conditions: natural 2D optotype viewing, 2D optotype viewing with polarized glasses, and 3D optotype viewing with polarized glasses. Recording with a smartphone, we captured videos to analyze the accurate time of spontaneous exodeviation and subsequent realignment before and after breaking fusion. Additionally, the correlation of stereopsis were also analyzed. RESULTS: A total of 48 patients (age range: 4-33y; 54.17% male) participated in the study. When viewing 3D optotypes with polarized glasses, their median control scores were 1 (interquartile range, 0-4) at distance and 0 (0-1) at near. These scores were significantly better than those observed under natural viewing conditions, which were 2.5 (1-5) at a distance and 1 (0-3) at near (Friedman test, P=0.049). Furthermore, those subjects who exhibited exophoria (realignment within 2 seconds) while viewing 3D optotypes with polarized glasses were more likely to have measurable stereo vision (Kendall's τb=-0.344, P=0.018). CONCLUSION: IXT patients exhibit enhanced control ability when using polarized glasses to view 3D optotypes, notably improving realignment capabilities. This expands our understanding of current tests and offers a potentially sensitive method for assessing IXT severity.

This article aims to comprehensively explore the progress of binocular vision function examination of intermittent exotropia(IXT)and its relationship with ametropia. As a common type of strabismus, IXT not only affects patients' visual experience and mental health, but also may develop into constant exotropia as they age. This article outlines the definition, prevalence, and clinical manifestations of IXT; introduces the examination methods of IXT, including strabismus angle examination, eye position control evaluation, and changes in accommodation and convergence functions. The article also explores the changes in stereopsis and other related examinations in IXT patients, providing a scientific basis for the comprehensive evaluation of IXT. In addition, the article deeply analyzes the relationship between IXT and ametropia, especially myopia, anisometropia, and hyperopia, pointing out the importance of refractive correction in improving binocular vision function and promoting the recovery of stereopsis. This article aims to provide references for clinical work and help doctors better understand the diagnosis and treatment of IXT.

Introduction: Amblyopia is two Snellen line difference between both eyes. Red filter therapy is a treatment option for amblyopia based on principle of syntonic phototherapy. The purpose of this study is to assess the stereopsis in amblyopic patient using syntonic phototherapy. Methods: A Qusai experimental study was conducted from August 2021 to December 2021 at Madina Teaching Hospital Faisalabad. A total 30 subjects of both gender and ages ranging between 8 to 18 years were included through a non-probability purposive sampling technique. The sample was considered of 15 anisometropic amblyopes and 15 strabismic amblyope. Data was collected using a Performa and pre assessments of stereopsis by Titmus fly chart were recorded without red filter. Red filter glasses were prescribed for 4 week, post assessment data was recorded after 4 weeks. Data was analyzed by using Paired sample T test and Independent Sample T test in SPSS 20 software. Results: After syntonic phototherapy significant improvement was seen, mean stereopsis was 48.00000 (p = 0.002) in anisometropic amblyopes while mean improvement of stereopsis 1.670.93333 (p = 0.00) in strabismic amblyopes. Anisometropic amblyopic patients showed significantly better improvement in stereopsis (p = 0.00) by syntonic phototherapy as compared to strabismic amblyopes. Conclusion: Significant improvement was seen in stereopsis, while improvement was more significant in anisometropic amblyopes as compared to strabismic amblyopes. Children were obsessed with the red filter glasses while their parents found syntonic therapy simple plus facile and gave good results. So, eye care professionals must be aware of this new therapy and they should keep syntonic phototherapy in mind whenever they are dealing with amblyopic patients. [ABSTRACT FROM AUTHOR]

Purpose: 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. Methods: 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, selfreported visual function using Catquest9SF (primary outcome measure), binocular visual acuity, stereopsis, and ocular dominance (secondary outcome measures) were compared. Results: A total of 151 patients (77 and 148 eyes in the Control and Intervention Groups, respectively) completed the followup. Patients who underwent surgery on both eyes exhibited significantly better selfreported 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. Conclusions: Surgery on both eyes resulted in significantly better selfreported visual function and stereopsis than surgery on one eye. [ABSTRACT FROM AUTHOR]

The purpose was to establish reference values for macular thickness, binocular vision, and stereopsis in premature infants aged 5-9 years and 10-13 years who underwent laser photocoagulation of avascular retinal zones due to retinopathy of prematurity (ROP); to assess and compare the data in an age-related perspective. Methods. Data from 24 premature infants who underwent ophthalmological examination, including optical coherence tomography, Titmus Stereo Fly Test, and the Worth 4 Dot Test, at ages 5-9 years and again at ages 10-13 years were analyzed. All children had undergone laser photocoagulation of avascular retinal zones due to ROP in infancy. Results. At ages 5-9 years, the mean central macular volume was 9.2 mm3, and the retinal thickness in the central fovea was 313.7 μm. At ages 10-13 years, the mean central macular volume was 9.1 mm3, and the retinal thickness in fovea was 320.8 μm. Normal binocular vision and stereopsis were observed in 79.2% and 33.3% of the children at the first time point, and in 87.5% and 45.8% at the second time point. Conclusions. No statistically significant difference in the central macular volume and macular thickness was detected between the two time points, (p>0.05). The thickest part of the macula was identified in the inner macula, followed by the outer macula, with the nasal quadrant being the thickest. Despite the anatomical peculiarities, high rates of binocular vision were observed at both time points, along with stereopsis at the second examination.

Abstract Background The pathogenesis of intermittent exotropia (IXT) remains unclear. The study aims to investigate alterations of resting-state networks (RSNs) in IXT adult patients using resting-state functional magnetic resonance imaging (rs-fMRI) data to explore the potential neural mechanisms. Methods Twenty-six IXT adult patients and 22 age-, sex-, handedness-, and education-matched healthy controls (HCs) underwent fMRI scanning and ophthalmological examinations. Brain areas with significant functional connectivity (FC) differences between the IXT and HC groups were selected as regions of interest (ROI) and mean z-scores were calculated to control for individual differences. Results Compared with HCs, IXT patients exhibited altered FC in various brain regions within RSNs involved in binocular fusion, stereopsis, ocular movement, emotional processes and social cognition, including the default mode network (DMN), the dorsal attention network (DAN), the visual network (VN), the sensorimotor network (SMN), the executive control network (ECN), the frontoparietal network (FPN) and the auditory network (AN). The degree of exodeviation was positively correlated with FC value of left middle occipital gyrus (MOG) within the VN. Correspondingly, we found a negative correlation between the degree of exodeviation and the FC value of left angular gyrus (AG) within FPN (P

Abstract Human eyes’ optical components are misaligned. This study presents comprehensive geometric constructions in the binocular system, with the eye model incorporating the fovea that is displaced from the posterior pole and the lens that is tilted away from the eye’s optical axis. It extends their previously considered horizontal misalignment with the vertical components. When the eyes’ binocular posture changes, 3D spatial coordinates of the retinal disparity (iso-disparity curves), the subjective vertical horopter, and the eye’s torsional orientation transformations are visualized in GeoGebra’s simulations. The consequences and functional roles of vertical misalignment of the eye’s optical components are explained in the following findings: (1) The classic Helmholtz theory, which states that the subjective vertical retinal meridian inclination to the retinal horizon explains the backward tilt of the perceived vertical horopter, is less relevant when the eye’s optical components are misaligned. Instead, the lens vertical tilt provides the retinal vertical criterion that explains the experimentally measured vertical horopter inclination. (2) Listing’s law, which originally restricts single-eye torsional positions and has imprecise binocular extensions, is formulated for binocular fixations using Euler’s rotation theorem. It, however, replaces Listing’s plane, which is defined for eyes looking at infinity, with the eyes muscles’ natural tonus resting position corresponding to the abathic distance fixation of empirical straight frontal horopter. This new meaning of Listing’s plane provides neurophysiological significance that has remained elusive.

Introduction: There remains a lack of compelling objective evidence on whether stereopsis is necessary for an ophthalmic surgical career. It is also unclear if high-grade stereoacuity correlates with better surgical performance. The present study attempts to address this question by comparing the simulated surgical performance of subjects with different levels of stereoacuity using a virtual reality (VR) intraocular surgical simulator (EYESi, VRmagic, Mannheim, Germany). Methods: Subjects were tested based on their stereoacuity level and stratified in three age-matched groups: normal stereopsis, subnormal stereopsis, and patients with no measurable stereoacuity in the clinical setting. Eleven subjects in each group to make a total of 33 subjects with no prior surgical experience were recruited from the IWK Health Centre, Halifax, Canada (REB trial registration: 1023183). Subjects performed three attempts on a standardized microsurgical module on the EYESi VR simulator. Results: There was no significant main effect of the stereo-group that the participants belonged to on their total scores, or on the time needed to complete the task, or on the odometer value, or on the amount of injury to surrounding tissues. Discussion: This study showed that for a basic simulated microsurgical task on the EYESI intraocular surgical simulator, the performance of individuals with reduced and absent stereoacuity was statistically indistinguishable from those with normal stereoacuity. Therefore, caution is still recommended when advocating for mandatory high level of stereoacuity as a requirement for admission to training programs in ophthalmology. There is still definite need for solid evidence that stereopsis is necessary to achieve satisfactory skills in ophthalmic microsurgery. [ABSTRACT FROM AUTHOR]

Introduction: The binocular system provides a stereoscopic view from slightly different retinal images and produces perceptual alternations, namely, binocular rivalry, from significantly different retinal images. When we observe a stereogram in which the stimulus configurations induce stereopsis and rivalry simultaneously, the binocular system prefers stereopsis to rivalry. However, changes in visual perception are yet to be investigated by parametrically manipulating the components of a stereogram. Methods: We examined stereopsis preferences in stereograms with various horizontal disparities. The stereograms of our paradigms included horizontal and vertical bars in one eye and a vertical bar alone in the other. Under experimental conditions, the vertical bar superimposed on the horizontal bar varied its position relative to the opposite vertical bar: range of horizontal disparity, 0.0′ to 42.3′. The superimposed vertical bar was absent under the control condition. Observers were instructed to indicate the disappearance of monocular horizontal bars, that is, targets, from their perception during the 30-s trials. Results: The total disappearance duration decreased under experimental conditions compared with that under control conditions, and it gradually increased with an increase in the disparity of the stereoscopic vertical bars. Discussion: These results indicate that the disparity in the stereoscopic components biases binocular perception away from the rivalry between the vertical and horizontal bars toward the stereopsis of the vertical bars. Furthermore, the disappearance duration showed a unimodal and asymmetric distribution across all disparity conditions. This suggests that rivalry processing occurs in parallel when stereopsis is dominant. We found that stereopsis preference is an outcome of binocular perception selection biased by disparity. [ABSTRACT FROM AUTHOR]

Human perception is often based on the integration of multiple sensory cues, where more statistically reliable cues are considered to have stronger influence on the percept. For example, in three-dimensional shape perception, binocular disparity is considered the most reliable cue at close distances, while pictorial cues like shading are considered less reliable. In three within-subject experiments, we instead show that shading can override disparity, a result that cannot be explained by its measured reliability, cue vetoing or cue promotion. Observers judged the shape of a disparity surface that was combined with different shading patterns. In all tests, shading altered the perceived shape specified by a strong disparity signal in a way that could not be predicted by standard accounts of three-dimensional perception. We find an example of unaccounted for cue cooperation, where shading becomes strong when it interacts with disparity. [ABSTRACT FROM AUTHOR]

Human eyes' optical components are misaligned. This study presents comprehensive geometric constructions in the binocular system, with the eye model incorporating the fovea that is displaced from the posterior pole and the lens that is tilted away from the eye's optical axis. It extends their previously considered horizontal misalignment with the vertical components. When the eyes' binocular posture changes, 3D spatial coordinates of the retinal disparity (iso-disparity curves), the subjective vertical horopter, and the eye's torsional orientation transformations are visualized in GeoGebra's simulations. The consequences and functional roles of vertical misalignment of the eye's optical components are explained in the following findings: (1) The classic Helmholtz theory, which states that the subjective vertical retinal meridian inclination to the retinal horizon explains the backward tilt of the perceived vertical horopter, is less relevant when the eye's optical components are misaligned. Instead, the lens vertical tilt provides the retinal vertical criterion that explains the experimentally measured vertical horopter inclination. (2) Listing's law, which originally restricts single-eye torsional positions and has imprecise binocular extensions, is formulated for binocular fixations using Euler's rotation theorem. It, however, replaces Listing's plane, which is defined for eyes looking at infinity, with the eyes muscles' natural tonus resting position corresponding to the abathic distance fixation of empirical straight frontal horopter. This new meaning of Listing's plane provides neurophysiological significance that has remained elusive. [ABSTRACT FROM AUTHOR]

Background: The pathogenesis of intermittent exotropia (IXT) remains unclear. The study aims to investigate alterations of resting-state networks (RSNs) in IXT adult patients using resting-state functional magnetic resonance imaging (rs-fMRI) data to explore the potential neural mechanisms. Methods: Twenty-six IXT adult patients and 22 age-, sex-, handedness-, and education-matched healthy controls (HCs) underwent fMRI scanning and ophthalmological examinations. Brain areas with significant functional connectivity (FC) differences between the IXT and HC groups were selected as regions of interest (ROI) and mean z-scores were calculated to control for individual differences. Results: Compared with HCs, IXT patients exhibited altered FC in various brain regions within RSNs involved in binocular fusion, stereopsis, ocular movement, emotional processes and social cognition, including the default mode network (DMN), the dorsal attention network (DAN), the visual network (VN), the sensorimotor network (SMN), the executive control network (ECN), the frontoparietal network (FPN) and the auditory network (AN). The degree of exodeviation was positively correlated with FC value of left middle occipital gyrus (MOG) within the VN. Correspondingly, we found a negative correlation between the degree of exodeviation and the FC value of left angular gyrus (AG) within FPN (P < 0.05). The FNC analysis between different RSNs also provides evidence on visual-motor cortical plasticity. Conclusions: IXT patients showed widespread changes of brain activity within RSNs related to binocular fusion, stereopsis, oculomotor control, emotional processes, and social cognition. These findings extend our current understanding of the neuropathological mechanisms of IXT. Trial registration: Beginning date of the trial: 2021-09-01. Date of registration:2021-07-18. Trial registration number: ChiCTR 2,100,048,852. Trial registration site: http://www.chictr.org.cn/index.aspx. [ABSTRACT FROM AUTHOR]

Recent advancements in cataract surgery have broadened its scope from mere vision restoration to include correction of refractive errors and presbyopia. This evolution has introduced multifocal and extended depth-of-focus (EDOF) intraocular lenses (IOLs), allowing enhanced vision across multiple distances. However, the influence of these advanced IOLs on stereopsis remains controversial. Factors influencing stereopsis after surgery include visual acuity, interocular differences, residual astigmatism, and the type of IOL, etc. Binocular vision integration and neuroadaptation further affect stereopsis, especially in cases of presbyopia-correcting IOLs. It is widely acknowledged that bilateral implantation of presbyopia-correcting IOLs yield superior stereopsis compared to unilateral implantation. However, there remains no consensus on whether binocular implantation of multifocal or monofocal IOLs provides superior stereopsis. Most studies suggest no significant difference in stereopsis between these two types of implants. Among different types of multifocal IOLs, refractive multifocal IOLs may offer better stereopsis than diffractive multifocal IOLs when implanted bilaterally. Emerging EDOF and hybrid multifocal-EDOF IOLs also demonstrate promising postoperative stereopsis. Additionally, a mix-and-match strategy with different types of IOLs implanted in each eye may result in interocular differences in visual acuity at certain distances, potentially affecting stereopsis. Nevertheless, with appropriate selection, most patients can achieve satisfactory postoperative stereopsis. This review synthesizes current literature on the effects of presbyopia-correcting IOLs on postoperative stereopsis recovery following cataract surgery. Studies on stereopsis outcomes with different IOLs have yielded mixed results, urging further investigation for optimized surgical strategies and patient outcomes. [ABSTRACT FROM AUTHOR]

Purpose: To investigate whether individuals with long‐term reduced stereopsis were able to obtain the same level of surgical skills in simulated vitreoretinal surgery on the Eyesi Surgical Simulator as individuals with normal stereopsis. Methods: Twenty‐four medical students were recruited and divided into two groups according to their degree of stereopsis: Group 1 (n = 12) included subjects with normal stereopsis (60 arcsec or lower) and Group 2 (n = 12) included subjects with reduced stereopsis (120 arcsec or higher). Stereopsis was tested using the TNO test (Lameris Ootech BV, Nieuwegein, the Netherlands). The participants were trained in virtual reality‐simulated vitreoretinal surgery and continuously measured using a test with solid validity evidence and a pre‐defined pass–fail score. All data were analysed using the Wilcoxon rank sum test. Results: We observed no differences in overall performance scores for any of the four modules. The participants with reduced stereopsis used 5.8 more attempts in bimanual training (p = 0.04), 8.8 more attempts in removal of posterior hyaloid (p = 0.04), 9.1 more attempts in navigation training (p = 0.20) and 0.3 fewer attempts in removal of internal limiting membrane (p = 0.69). Conclusion: The final performance scores on the Eyesi Surgical Simulator were independent of the degree of stereopsis. However, the number of attempts to achieve the pre‐defined pass–fail score increased significantly with reduced stereopsis in two of four modules. These results indicate that a high degree of stereopsis is not necessary to become proficient in microsurgery but may prolong the learning curve. [ABSTRACT FROM AUTHOR]

Clinical relevance: New digital systems are being developed for evaluating different aspects of the visual function, such as binocularity, and it is important to know their real performance in clinical practice in order to use them appropriately. Background: The aim was to compare binocular vision measures obtained with an online digital platform with conventional measures using prisms and printed tests. Methods: Prospective study enrolling 49 healthy patients (mean age: 35.5 ± 13.6 years). A complete visual examination was performed including measurement of near phoria (cover test), negative fusional vergence (NFV) and positive fusional vergence (PFV) ranges (prism bar), and stereopsis (24 patients Randot Stereo Test and 25 patients TNO Random Dot Test 19th edition). These same parameters were also measured with the Bynocs system (Kanohi Eye Pvt Ltd). Bland – Altman plots were used to analyse the agreement between methods. Results: Digital measurement of near phoria was significantly lower than that obtained with the cover test, with a median difference (MD) of 4.71 (−0.07–20.07) prism dioptres (pd) (p < 0.001). No significant differences were found between Bynocs and prism bar methods in NFV break (MD 2.00, range −21–26 pd, p = 0.584) and recovery points (MD 0.00, range −16–24 pd, p =.571). Near PFV were significantly lower with Bynocs (break: MD −9.00, range −38–12 pd; recovery: MD −14.00, range −43–20 pd; p < 0.001). Bynocs stereoacuity threshold was significantly lower than that obtained with TNO (p = 0.004), but significantly higher compared to Randot (p < 0.001). Large and clinically relevant confidence intervals for the comparison between digital and conventional measures were detected in Passing-Bablok analysis. Conclusions: Digital measures of near phoria, NFV, PFV, and stereopsis with the Bynocs platform cannot be used interchangeably with conventional measures. The normal ranges of normality for this new tool are defined. [ABSTRACT FROM AUTHOR]

The purpose was to establish reference values for macular thickness, binocular vision, and stereopsis in premature infants aged 5-9 years and 10-13 years who underwent laser photocoagulation of avascular retinal zones due to retinopathy of prematurity (ROP); to assess and compare the data in an age-related perspective. Methods. Data from 24 premature infants who underwent ophthalmological examination, including optical coherence tomography, Titmus Stereo Fly Test, and the Worth 4 Dot Test, at ages 5-9 years and again at ages 10-13 years were analyzed. All children had undergone laser photocoagulation of avascular retinal zones due to ROP in infancy. Results. At ages 5-9 years, the mean central macular volume was 9.2 mm3, and the retinal thickness in the central fovea was 313.7 μm. At ages 10-13 years, the mean central macular volume was 9.1 mm3, and the retinal thickness in fovea was 320.8 μm. Normal binocular vision and stereopsis were observed in 79.2% and 33.3% of the children at the first time point, and in 87.5% and 45.8% at the second time point. Conclusions. No statistically significant difference in the central macular volume and macular thickness was detected between the two time points, (p>0.05). The thickest part of the macula was identified in the inner macula, followed by the outer macula, with the nasal quadrant being the thickest. Despite the anatomical peculiarities, high rates of binocular vision were observed at both time points, along with stereopsis at the second examination. [ABSTRACT FROM AUTHOR]

Yumi Suzuki, Takafumi Aoki, Akane Tomita, Tadahiro Mitsukawa, Yukiko Hama, Masakazu Yamada Department of Ophthalmology, Kyorin University School of Medicine, Mitaka, Tokyo, JapanCorrespondence: Yumi Suzuki, Email yumis@ks.kyorin-u.ac.jpPurpose: To evaluate the efficacy and safety of slanted bilateral lateral rectus recession (BLR-rec) for treating convergence insufficiency-type intermittent exotropia (CI-IXT) in children.Methods: In this retrospective cohort study, 26 patients aged < 16 years with CI-IXT who underwent BLR-rec between August 2016 and July 2021 with six months of follow-up data post-surgery were classified into slanted BLR-rec group (n = 14) and standard BLR-rec group (n = 12; equal-length recession of the upper and lower horns of the LR muscle). Surgical outcomes were compared between the groups.Results: In the slanted and standard groups, the preoperative distance exodeviation was 27.9 ± 5.5 and 30.8 ± 10.0 prism diopter (PD) (p = 0.63), near exodeviation was 41.1 ± 5.6 and 42.9 ± 9.2 PD (p = 0.75), and difference between near and distance deviation (N-D deviation difference) was 13.2 ± 3.2 and 12.1 ± 3.3 PD (p = 0.30), respectively. The ratio of postoperative and preoperative N-D deviation difference was compared between the slanted BLR and standard BLR groups at six months postoperatively. The results revealed that the ratio for slanted-BLR was 0.44 ± 0.19, and for standard-BLR was 0.84 ± 0.24. In the standard group, stereoacuity remained unchanged post-surgery compared to that pre-surgery, while the slanted group showed significant improvement (p < 0.05, Wilcoxon signed-rank test).Conclusion: Compared with the standard BLR-rec procedure, the slanted BLR-rec procedure reduced N-D deviation differences in CI-IXT, positively impacting gross stereopsis.Keywords: bilateral lateral rectus recession, convergence insufficiency-type intermittent exotropia, postoperative diplopia, consecutive esotropia, stereopsis

AIM: To investigate botulinum toxin A (BTXA) efficacy on small-angle (≤25Δ) acute acquired concomitant esotropia (AACE) in early-stage patients. METHODS: The electronic medical record data of AACE patients during March 2019 and June 2023 were collected in this retrospective and hospital-based cohort study. A total of 72 small-angle AACE patients received BTXA extraocular muscle injection. Patients were grouped by onset-to-treatment time (Group A: ≤6mo, Group B: >6mo). Deviation of esotropia, eye alignment and stereopsis were analyzed at the period of pre/post-injection (1wk, 1, 3, and 6mo). Orthophoria rate at 6mo (horizontal deviation 0.05) between two groups except onset-to-treatment time (2mo vs 11mo, P0.05); while in 3 and 6mo Group A was significantly smaller than group B (all P6mo) may reduce BTXA efficacy. Early BTXA intervention benefits long-term eye alignment and stereopsis recovery.

Purpose: To evaluate stereopsis in term-born, preterm, and preterm children with and without retinopathy of prematurity (ROP) and its treatment. Methods: The cross-sectional study included 322 children between 3 and 11 years of age born term or preterm, with or without ROP, and with or without treatment for ROP. The ROP treatments were laser therapy, intravitreal injection (IVI) of anti-vascular endothelial growth factor, or their combination. Stereoacuity was measured using the Titmus Stereo Test, and the results among various age groups were analyzed. Results: Stereopsis was found to improve with increasing age at testing (P < 0.001) across the entire study population. The term group exhibited significantly better stereoacuity than the preterm group (P < 0.001). At 3–5 years and 6–8 years, the preterm children without ROP exhibited significantly better stereoacuity than did those with ROP (P < 0.001 and P = 0.02, respectively); however, at 9–11 years, both groups exhibited similar stereoacuity (P = 0.34). The stereoacuity in the children with untreated ROP was similar to that of the children with treated ROP in all age groups (P > 0.05). No significant differences in stereopsis were identified between children with ROP treated with laser versus with IVI (P > 0.05). From multivariate analysis, younger age at testing (P = 0.001) and younger gestational age (P < 0.001) were associated with poorer stereopsis. Conclusions: Stereopsis development gradually improved with age in all groups. The children born preterm exhibited poorer stereoacuity than those born term. Children with ROP treated with laser photocoagulation versus IVI may exhibit similar levels of stereoacuity. Younger age at testing and gestational age were independent risk factors for poorer stereoacuity. [ABSTRACT FROM AUTHOR]

Purpose: 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. Study design: 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. Results: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the relationship between hand-eye reaction time and stereopsis in adolescents aged 15-19. A total of 150 participants (70 males, 80 females) with an average age of 16.76±1.21 years participated in the study. First, hand-eye reaction time measurements were taken from the participants. Then, the stereo fly test was performed, and stereopsis values were recorded. A statistically positive and moderately significant relationship was detected between hand-eye reaction time and stereopsis. A statistically positive and moderately significant relationship was found between hand-eye reaction time and stereopsis in adolescent males. There was a statistically positive and low significant relationship between handeye reaction time and stereopsis in adolescent females. In conclusion, this study examined the relationship between hand-eye reaction time and stereopsis in adolescents aged 15-19 years and revealed that there is a link. These results support that depth perception plays a role in adolescents' motor skills and performance in daily activities. [ABSTRACT FROM AUTHOR]

IntroductionThe binocular system provides a stereoscopic view from slightly different retinal images and produces perceptual alternations, namely, binocular rivalry, from significantly different retinal images. When we observe a stereogram in which the stimulus configurations induce stereopsis and rivalry simultaneously, the binocular system prefers stereopsis to rivalry. However, changes in visual perception are yet to be investigated by parametrically manipulating the components of a stereogram.MethodsWe examined stereopsis preferences in stereograms with various horizontal disparities. The stereograms of our paradigms included horizontal and vertical bars in one eye and a vertical bar alone in the other. Under experimental conditions, the vertical bar superimposed on the horizontal bar varied its position relative to the opposite vertical bar: range of horizontal disparity, 0.0′ to 42.3′. The superimposed vertical bar was absent under the control condition. Observers were instructed to indicate the disappearance of monocular horizontal bars, that is, targets, from their perception during the 30-s trials.ResultsThe total disappearance duration decreased under experimental conditions compared with that under control conditions, and it gradually increased with an increase in the disparity of the stereoscopic vertical bars.DiscussionThese results indicate that the disparity in the stereoscopic components biases binocular perception away from the rivalry between the vertical and horizontal bars toward the stereopsis of the vertical bars. Furthermore, the disappearance duration showed a unimodal and asymmetric distribution across all disparity conditions. This suggests that rivalry processing occurs in parallel when stereopsis is dominant. We found that stereopsis preference is an outcome of binocular perception selection biased by disparity.

Background: South Africa has a high mortality rate because of road traffic accidents (RTAs) compared to other countries. Aim: To determine the visual functions and their association with the occurrence of RTAs among vehicle drivers in the Gauteng province of South Africa. Setting: Eight driver’s license testing centres (DLTCs) in the Gauteng province. Methods: A cross-sectional study involving a multi-stage random sampling approach was conducted. Data collected using the questionnaire included participants’ demographic details. Ocular health examination included the measurement of visual acuity (VA), refractive errors, visual fields, colour vision, stereopsis, contrast and glare sensitivity. Results: A total of 579 motor vehicle drivers were enrolled in this study. Drivers who reported daily alcohol consumption had a higher risk of being involved in RTAs (odds ratio [OR] = 1.8, 95% confidence interval [95%CI] = 1.09–2.99, P = 0.02). Visual acuity (OR = 1.43, 95%CI = 0.99–2.06, P = 0.05), refractive errors (P = 0.03, χ2 = 61.57), abnormal contrast sensitivity (OR = 0.53, 95%CI = 0.31–0.93, P = 0.03) and deutan colour vision defects (P = 0.002, χ2 = 31.42) were significantly associated with RTAs. Visual field defects (OR = 0.98, 95%CI = 0.97–1.00, P = 0.09), stereopsis anomaly (OR = 1.00, 95%CI = 0.99–1.00, P = 0.35) and abnormal glare sensitivity (OR = 1.00, 95%CI = 0.99–1.01, P = 0.32) were not significantly associated with the occurrence of RTAs. Conclusion: These results suggest reviewing the visual requirements for obtaining a driver’s license by incorporating colour vision and contrast sensitivity assessment. Contribution: The study addresses a gap in the country’s current vision testing standards for driving.

The human visual system evolved in environments with statistical regularities. Binocular vision is adapted to these such that depth perception and eye movements are more precise, faster, and performed comfortably in environments consistent with the regularities. We measured the statistics of eye movements and binocular disparities in virtual-reality (VR) - gaming environments and found that they are quite different from those in the natural environment. Fixation distance and direction are more restricted in VR, and fixation distance is farther. The pattern of disparity across the visual field is less regular in VR and does not conform to a prominent property of naturally occurring disparities. From this we predict that double vision is more likely in VR than in the natural environment. We also determined the optimal screen distance to minimize discomfort due to the vergence-accommodation conflict, and the optimal nasal-temporal positioning of head-mounted display (HMD) screens to maximize binocular field of view. Finally, in a user study we investigated how VR content affects comfort and performance. Content that is more consistent with the statistics of the natural world yields less discomfort than content that is not. Furthermore, consistent content yields slightly better performance than inconsistent content.

Background Accommodative esotropia (ET) usually presents in preschool years. It is often intermittent, and the deviation is typically eliminated by controlling the accommodative effort with optical correction of hypermetropia. Objective The aim of this study was to document the clinical features and to assess the functional outcome in patients with refractive accommodative esotropia (RAE) in terms of amblyopia and binocular vision and to analyze the possible risk factors involving the development of amblyopia. Patients and methods We retrospectively reviewed the records of 60 patients diagnosed with fully accommodative esotropia (FAET). Multiple parameters were reviewed, including age of onset, age of initiation of treatment, initial and final cycloplegic refraction, distance and near deviation with and without glasses, stereoacuity, presence of anisometropia, and change in hyperopia. Results The mean age of onset and age of initiation of treatment were 2.53±1.42 and 2.73±1.25 years, respectively. The mean spherical equivalent refraction at the initial visit was +5.36±1.48 diopters (D) in the right eyes and +5.62±1.43 D in the left eyes. Anisometropia was present in 33.33% of the patients. Fusion was achieved in 90% of the patients, with 38 (63.33%) patients having stereopsis ranging from 40–100 sec/arc and 22 (36.67%) having stereopsis between 100 and 200 sec/arc with the Titmus fly test. Amblyopia was reduced from 50% to 16.67%. Anisometropia was found to be the only statistically significant risk factor for the development of amblyopia (P

Abstract Objective To investigate the recovery of binocular stereopsis recovery and its influencing factors in children with intermittent exotropia after successful correction of eye position. Methods Prospective 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. Results Six 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

BACKGROUND: Pediatric cataract is an important cause of avoidable childhood blindness in India. Although there are studies on clinical features and visual acuity outcomes of pediatric cataract surgery, there are no studies that look into aspects of color vision, stereopsis, and cognitive functions in children with cataracts. Studying these parameters pre- and postsurgery will help us assess the overall components of visual function that are critical for the child's development. With this in mind, we aimed to study the clinical features, outcome of treatment, color vision, stereopsis, and cognitive functions in children with cataracts. MATERIALS AND METHODS: Design: Hospital-based prospective descriptive study. Data of 68 children (0 < 18 years) were collected, on the clinical features, visual acuity, color vision, stereopsis, and social and intelligence quotient before and after surgery. Data analysis was performed using Graph Pad Prism software version 9.4.0 (673). RESULTS: Ninety eyes of 68 children (36-bilateral/32-unilateral) were operated. A total of 46 children were available at 6 months' follow-up (28 bilateral cataracts (46 eyes) and 18 unilateral cataracts). Nineteen (67.8%) of the bilateral, had a best corrected visual acuity of 6/6-6/18 in the better eye and nine (50%) of the unilateral had a visual acuity of 6/18-6/6 in the operated eye. Preoperatively, 61.5% of the children had a stereopsis of 100-600 arc-secs. Post-operatively, 84.4% of the children had a stereopsis in the range <50-600 arc-secs. All children had color vision deficiency. Preoperatively, 62% of the children had strong and moderate deficiency, whereas postoperatively, 66.6% had mild deficiency. We found negative correlation (r = -0.503) between social quotient and percentage of visual impairment indicating that when visual impairment increases social quotient decreases. The mean IQ preoperatively was 94.36 ± 2.98 and postoperatively 101.38 ± 2.77, with 95% confidence interval P value was statistically significant (P = 0.0001). This shows better and faster performance postoperatively. CONCLUSION: Majority of the children had improved visual acuity after surgery. This outcome can be extrapolated to the overall improvement in stereopsis, color vision, and higher cognitive functions.. [ABSTRACT FROM AUTHOR]

Introduction: Dentistry is a profession that requires a high level of the hand–eye coordination. Although considerable attention has been put on dental students' manual dexterity, little emphasis was made on students' visual competency as a variable influencing their competency. In this study, we aimed to assess the association between dental students' stereopsis and their pre‐clinical performance. Methods: Dental students (n = 49) were required to perform the porcelain‐fused‐to‐crown preparation for a lower first molar and an upper central incisor plastic teeth mounted on phantom heads. Performance was assessed by two faculty members based on two rubrics, which collectively included 11 assessment criteria. Afterward, students undertook a stereoacuity test using Randot stereotest. Stereopsis values greater than 40 arc/s were considered abnormal. Results: A significant negative correlation was seen between stereopsis scores and students' grades for the upper incisor (p < 0.01), but not for the lower molar. An association was also seen between abnormal stereopsis and students' poor performance in preparing the finish line of the incisor tooth (p = 0.024). Conclusion: Abnormal stereopsis can impact dental students' performance, particularly when preparing teeth indirectly using a dental mirror. Dental educators should give attention to students' stereoacuity, in a manner similar to that given to students' manual dexterity. [ABSTRACT FROM AUTHOR]

Background: The ability to merge the two retinal images to perceive depth (stereopsis) plays an important role in human vision. Its proper development requires binocular alignment and good visual acuity in both eyes during childhood. Because treatments are more effective when applied early, early diagnosis is important. Unfortunately, assessing stereo deficiencies in infants and young children remains challenging. Recently, it has been shown that ocular-following responses (OFRs; reflexive, short-latency eye movements induced by the sudden motion of a large textured pattern) are sensitive to changes in interocular correlation, making them potentially useful for stereo deficiency assessments. To test this hypothesis, we measured OFRs elicited by dichoptic stimulation in children with normal and compromised stereopsis (due to amblyopia). Methods: Two groups of six children (age- and sex-matched: 3M/3F aged 7–12 yo), one with compromised stereopsis and one with normal stereopsis, were included. OFRs were recorded using a custom high-resolution video eye-tracking system. The relative differences between eye displacement induced by correlated stimuli (up-correlated–down-correlated) and anticorrelated (up-anticorrelated–down-anticorrelated) were compared. Results: We found significant differences between OFRs induced by two dichoptic conditions (correlated and anticorrelated stimuli) in most children with normal stereopsis, whereas no differences were observed in children with compromised stereopsis, indicating a lack of disparity detectors. Conclusions: OFRs might thus be exploited as a diagnostic tool for the objective identification of stereo deficiencies in children. This might lead to improved early diagnosis and treatment outcomes for conditions like amblyopia and strabismus. [ABSTRACT FROM AUTHOR]

Introduction: Changes in vision that occur in normal healthy aging can be seen in fundamental measures of monocular vision. However, the nature of the changes in binocular vision with age remain unclear. Methods: A total of 28 older (53-66 years) and 28 younger adults (20-31 years) were enrolled in this study. We performed a battery of tests to assess differences in monocular contrast thresholds and various binocular visual functions including dichoptic masking weight and strength, the binocular balance point for fused stimuli, and stereoacuity in the aging and control groups. Results: Aging significantly increased monocular contrast thresholds (p < 0.001). Although this suggests that aging reduces the effective "input gain" to vision, we also found a significantly elevated contribution of those weaker signals to interocular suppression (p < 0.001). Consequently, there was no significant net difference in the strength of interocular suppression (p = 0.065). We did not find a significant difference of absolute balance point between the two groups (p = 0.090). Lastly, the mean stereoacuity was worse in the older group compared to the younger group (p = 0.002). Discussion: Our findings confirm previous results showing differences in contrast sensitivity and stereoacuity with aging. Furthermore, we find a change in interocular suppression that is a possible consequence of the change in contrast sensitivity. It is suggestive of a cortical system that maintains a homeostatic balance in interocular suppression across the lifespan. [ABSTRACT FROM AUTHOR]

Introduction: Near response is a complex synkinesis required for a good binocular vision. accommodative convergence per diopter of accommodation (AC/A ratio) is a value of significance in this synkinetic movement. In addition, the value is used to classify and treat ocular movement abnormalities. The two commonly used methods for determining the AC/A ratio are Gradient Method and Heterophoria method. The normative data for Indian population by gradient method was described in two studies. However, the normative data for heterophoria method is lacking in Indian population. Objective: The purpose of this cross-sectional study is to generate the normative value for AC/A ratio for the Indian population by heterophoria method. One hundred healthy ophthalmologically normal adults with no presbyopia or refractive error were chosen consecutively among the attendants of patients visiting the center. Materials and Methods: After thorough ophthalmic evaluation, the participants were subjected to AC/A ratio calculation by heterophoria method using 6/9 fixation target and PMMA Prism bar. Results: One hundred healthy adults with no refractive error or ocular abnormality were selected with a mean age of 25.70 years (standard deviation [SD] = 4.92) and equal gender distribution. The mean Inter Pupillary Distance (IPD) was found to be 62.88 mm with a SD of 3.91 mm. The average phoria at distance was 1.82 prism diopters (SD = 2.03pd) of exophoria and for near at 33 cm was 4.20pd (SD = 1.92pd). The mean AC/A ratio by heterophoria method was found to be 5.49PD/D with an SD of 0.54PD/D. The highest being 6.90PD/D and the lowest being 4.27PD/D with no statistically significant difference between genders. Conclusion and Relevance: According to the previous studies, the normative data arrived is lesser than the value reached in the current study for similar population groups when considering both methodologies of testing. This variation between the gradient method and heterophoria method accounted for by the involvement of proximal convergence during the heterophoria method.

AIM: To analyze the efficacy of multimedia visual physiological stimulation combined with stereoscopic system training in the treatment of ametropic amblyopia in children.METHODS: A total of 102 patients(102 eyes)with ametropic amblyopia admitted to our hospital from June 2021 to June 2022 were randomly divided into two groups. The control group consisted of 51 patients(51 eyes)who received multimedia visual physiological stimulation on the basis of conventional treatment, while the observation group consisted of 51 patients(51 eyes)who received stereoscopic training on the basis of the control group. The binocular fusion function, binocular stereopsis and binocular disparity of the two groups of children were evaluated at 3mo after treatment, and the clinical efficacy was assessed based on the improvement of vision.RESULTS: After 3mo of treatment, the normal rates of binocular fusion function, binocular stereopsis, and binocular disparity in the observation group were significantly higher than those in the control group(all P

Background: There are individual reports on the effect of some preoperative characteristics of visual functions (like convergence, angle of deviation, presence of fusion and type of binocular vision) on the success of exotropia surgery. To date, however, it has not been established what are the major diagnosis-related prognostic factors for the success of surgery for exotropia. Purpose: To identify the preoperative characteristics of visual functions which have an effect on the success of surgery for exotropia. Material and Methods: Of the 59 exotropes (age range, 10 to 21 years) included in this study, 33 had basic constant exotropia (group 1) and 26, intermittent exotropia (group 2). Patients underwent an ophthalmological and ortoptic examination of the motor and sensory systems of the eye. Patients with surgery success (postoperative orthotropes) were compared to those who had a residual exotropia of more than 10 prism diopters (PD) postoperatively in terms of the preoperative accommodative convergence–accommodation (AC/A) ratio, near point of convergence (NPC), distance stereopsis and near stereoacuity threshold. Results: Our analysis of the preoperative NPC, AC/A ratio and stereopsis for the group with postoperative orthotropic alignment and the group with postoperative exotropic alignment found preoperative close to normal values of AC/A ratio (4.0 ± 1.65 PD/D), NPC (8.03 ± 3.02 cm), the presence of distance stereopsis and near stereopsis (passing the 200 second of arc image on the Lang II stereo card) and the absence of medial rectus hypofunction of hyperfunction in 83.05% of patients of the former group. Conclusion: Preoperative close to normal values of AC/A ratio (4.0 ± 1.65 PD/D), NPC (8.03 ± 3.02 cm), the presence of distance stereopsis and near stereopsis (passing the 200 second of arc image on the Lang II stereo card) and the absence of medial rectus hypofunction of hyperfunction can be the factors favoring the success of exotropia surgery.

Background and purpose: Depth perception (stereopsis) is the ability to perceive depth in visual space through sensory integration of retinal images in both eyes and is achieved through binocular perception in specific visual pathways in the cerebral cortex. Medical students use a variety of diagnostic tools during their training, and a lack of normal stereoacuity can affect their professional performance. Understanding the appropriate stereopsis also plays a crucial role in their future careers. The purpose of this study was to determine stereopsis using the Titmus test in subjects with and without refractive errors. Materials and methods: In this cross-sectional study, 115 students at Mazandaran University of Medical Sciences who met the inclusion criteria were randomly selected. Based on the presence or absence of refractive errors through retinoscopy, they were divided into symptomatic and asymptomatic groups. The stereopsis was measured by the Titmus test. Data were analyzed in SPSS V 21, and the frequency of stereoacuity was reported. Results: A total of 115 people enrolled in this study. Males accounted 55.7% (n=64) of the subjects and 44.3% (n=51) of the subjects were females. The mean age of male and female participants were 25.20±1.88 and 24.15±1.79 years, respectively (P>0.05). There were 40 (34.8%) students with refractive errors and 75 (65.2%) without refractive errors. The mean values for stereopsis in symptomatic and asymptomatic subjects were 42.90±29.59 and 29.24±12.96 seconds/arc, respectively(P=0.001). These values in males and females were 32.12±20.73 and 36.33±21.85 seconds/arc, respectively (P=0.293). The mean test time was 57.75±18.43 and 56.0±18.49 seconds in symptomatic and asymptomatic subjects (P=0.629), and 54.45±17.82 and 59.31±18.94 seconds in males and females (P=0.160), respectively. Conclusion: Titmus stereo test was found to be an effective test for evaluating the depth perception of symptomatic and asymptomatic subjects. There was no difference in the stereopsis between males and females in this study.

Background: Accurate differentiation between stereopsis assessments in the natural and dichoptic presentation states has proven challenging with commercial stereopsis measurement tools. This study proposes a novel method to delineate these differences more precisely. Methods: We instituted two stereopsis test systems predicated on a pair of 4K smartphones and a modified Frisby Near Stereotest (FNS) version. Stereoacuity was evaluated both in the natural environment state (via the modified FNS) and the dichoptic state (via smartphones). Thirty subjects aged 20 to 28 years participated in the study with the best-corrected visual acuity (VA) of each eye no less than 0 logMAR and stereoauity of no worse than 40". Varying degrees of monocular VA loss were induced using the fogging method, while this study does not explore conditions where the VA of both eyes is worse than 0 logMAR. Results: When the VA difference between the two eyes did not exceed 0.2 logMAR, the modified FNS produced lower stereoacuity values compared to the 4K smartphones (Wilcoxon signed-rank test: difference = 0 logMAR, Z = -3.879, P < 0.001; difference = 0.1 logMAR, Z = -3.478, P = 0.001; difference = 0.2 logMAR, Z = -3.977, P < 0.001). Conversely, no significant differences were observed when the binocular vision difference exceeded 0.2 logMAR (difference = 0.3 logMAR, Z = -1.880, P = 0.060; difference = 0.4 logMAR, Z = -1.784, P = 0.074; difference = 0.5 logMAR, Z = -1.812, P = 0.070). Conclusion: The findings suggest that stereoacuity values measurements taken in the natural environment state surpass those derived from the dichoptic presentation. However, the observed difference diminishes as stereopsis decreases, corresponding to an increase in induced anisometropia. [ABSTRACT FROM AUTHOR]

Background: Ocular following responses (OFRs)—small-amplitude, short-latency reflexive eye movements—have been used to study visual motion processing, with potential diagnostic applications. However, they are difficult to record with commercial, video-based eye trackers, especially in children. Objective: We aimed to design and develop a noninvasive eye tracker specialized for measuring OFRs, trading off lower temporal resolution and a smaller range for higher spatial resolution. Methods: We developed a high-resolution eye-tracking system based on a high-resolution camera operating in the near-infrared spectral range, coupled with infrared illuminators and a dedicated postprocessing pipeline, optimized to measure OFRs in children. To assess its performance, we: (1) evaluated our algorithm for compensating small head movements in both artificial and real-world settings, (2) compared OFRs measured simultaneously by our system and a reference scleral search coil eye-tracking system, and (3) tested the system's ability to measure OFRs in a clinical setting with children. Results: The simultaneous measurement by our system and a reference system showed that our system achieved an in vivo resolution of approximately 0.06°, which is sufficient for recording OFRs. Head motion compensation was successfully tested, showing a displacement error of less than 5 μm. Finally, robust OFRs were detected in 16 children during recording sessions lasting less than 5 minutes. Conclusions: Our high-resolution, noninvasive eye-tracking system successfully detected OFRs with minimal need for subject cooperation. The system effectively addresses the limits of other OFR measurement methods and offers a versatile solution suitable for clinical applications, particularly in children, where eye tracking is more challenging. The system could potentially be suitable for diagnostic applications, particularly in pediatric populations where early detection of visual disorders like stereodeficiencies is critical. [ABSTRACT FROM AUTHOR]

Objective: This study aims to examine the effects of virtual reality (VR) usage on the eyes and investigate the parameters responsible for the subsequent discomfort sensation. Materials and Methods: This prospective study enrolled 20 healthy volunteers who were engaged in a 10-minute VR game session. Refractive errors, kappa angles, phoria presence, accommodative responses, and scotopic, mesopic, and photopic pupillometry values were recorded before and after using VR. A Virtual Reality Sickness Questionnaire (VRSQ) was applied to assess discomfort, and the relation with evaluated parameters was investigated. Results: Twenty volunteers (mean age 29.80±0.57 years) included 11 females (55%) and 9 males (45%). The mean spherical equivalent refractive error was -- 1.94±0.28 diopters and 5 (25%) volunteers had phoria. Average kappa angles were 0.23±0.02 mm (x-axis) and 0.11±0.01 mm (y-axis). Post-VR, the median [(interquartile range (IQR)] stereopsis decreased from 30 (30-60) to 60 (60-60) arc seconds (P<0.001). Pupil sizes increased significantly across all lighting conditions (P<0.001). Accommodation did not significantly change post-VR (P>0.05). VRSQ scores correlated positively with phoria and kappa-x angle (r=0.458, P=0.003 and r=0.330, P=0.038) while negatively with stereopsis and kappa-y angle (r=-0.375, P=0.017 and r=-0.326, P=0.04). Conclusion: Virtual reality use reduces depth perception and induces significant mydriasis across lighting conditions. Post-VR discomfort feeling may be related to phoria, kappa angle, and stereopsis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Amblyopia is a neurological deficit in binocular vision that affects 3% of the population and is the result of disruptions in early visual development. OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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. [ABSTRACT FROM AUTHOR]

Amblyopia affects development of children's monocular vision and binocular function and becomes a largely intractable problem with increasing aging. This study is to investigate the binocular function and evaluate efficacy of digital therapy in children 8–13 years of age with anisometropic amblyopia. The patients in the digital therapy group performed the training with the digital amblyopia therapeutic software. The visual acuity and binocular function (perceptual eye position [PEP], suppression, and stereopsis) were examined at the first visit and 3-month post-treatment. Twenty-three cases in the control group and 25 cases in the digital therapy group were enrolled. The results revealed that 3-month digital therapy can effectively improve corrected distance visual acuity (CDVA) and improve the binocular function, including PEP, suppression, and second-order stereopsis in children with anisometropic amblyopia, 8–13 years of age. Digital therapy for amblyopia can effectively improve monocular CDVA of amblyopic eyes and binocular function in older children with anisometropic amblyopia. [ABSTRACT FROM AUTHOR]

Background: To determine the prevalence of anisometropia and its association with stereopsis and amblyopia in Goan school children. Methods: A cross-sectional study was conducted on students between 9 and 14 years of age from two randomly selected schools in Goa. All students underwent an assessment of uncorrected and best-corrected visual acuity, stereo acuity, and complete ophthalmic examination. Children with refractive errors without any other coexisting ocular pathologies were included. Refractive correction of children with a best-corrected visual acuity of logMAR 0.0 was measured using a manual lensometer. Subjects with visual acuity greater than logMAR 0.2, further improving with pinhole, were subjected to objective and subjective refraction. The prevalence of anisometropia, anisometropic amblyopia, and degree of stereo acuity in anisometropic children was assessed. Results: Four hundred and six children were screened for refractive errors. Sixty-four children were found to have refractive errors, of which 58 students (90.6%) were myopic, and six (9.4%) were hyperopic. The prevalence of anisometropia of ≥1.0 D spherical equivalent was found in 12 students (18.75%), among whom myopia was the most common refractive error (9.75%). Anisometropic amblyopia was noted in eight students (66.6%), five of whom were myopes and three hyperopes. All three hyperopic anisometropes (100%) had amblyopia. Seventy-five percent of children with poor stereo acuity, ranging from ≥160 seconds of arc, belonged to the hyperopic anisometropia group. Conclusion: Amblyopia is more prevalent among anisometropes than isometropes, with hyperopic anisometropes having poor stereoacuity and being more likely to develop amblyopia. Hence, early identification and treatment of anisometropia will significantly reduce the risk of amblyopia in school children. [ABSTRACT FROM AUTHOR]

Purpose: A macular lesion preventing the foveal fixation could lead to the fixation from eccentric points in age-related macular degeneration (AMD). There is a lack of knowledge about the binocular function of these patients and the role of preferred retinal locus in binocularity. This study aims to examine binocular fusion and stereopsis in a unique group of patients who have unilateral choroidal neovascular membrane (CNVM) involving the fovea. Methods: Twenty-five patients with the diagnosis of the CNVM in one eye and type I or type II drusen in the other eye were examined. The Bagolini test was performed to determine binocular fusion. The Stereo Butterfly test was used for stereo acuity determination. CNVM measurements were done with optical coherence tomography. Results: In the Bagolini test, 12 patients saw two lines with break in one of the lines. Eleven patients saw two lines crossing at higher or lower than the center. Two patients saw only one line. One of 25 patients had gross stereopsis (2500 s of arc). The area of the CNVM was extending to the perifovea in 2 patients suppressing the other eye. In remaining 23 patients, CNVM was located in fovea or extended up to the parafovea. Conclusion: Binocular fusion is possible if the CNVM lesion size and location allow usage of the fovea-parafovea visual angle. Our study results support that the binocular function of patients with neovascular AMD depends on the corresponding retinal areas and the fusional limit of non-corresponding points. [ABSTRACT FROM AUTHOR]

AIM: To determine the effects of change in light conditions on refractive error and visual functions including visual acuity, stereopsis and contrast sensitivity. METHODS: This cross-sectional study was conducted in the optometry clinic of the Shahid Beheshti School of Rehabilitation on 48 students in 2021-2022. All of them had eye health and normal visual function and could have refractive errors or not. Light intensity of 4 lx was considered equivalent to photopic light condition and light intensity of 1 lx was considered to be equivalent to mesopic light condition. The amount of refractive error was checked by auto refractometer and its changes in mesopic light condition were subjectively measured. Also, visual acuity, stereopsis and contrast sensitivity (in five spatial frequencies of 1.5, 3, 6, 12, and 18 cycles per degree), were measured first in photopic light condition and then in mesopic light condition, by Snellen control vision chart, stereo butterfly test and the M&S technology monitor test respectively. RESULTS: In the 48 student subjects with an average age of 22.69±3.56y, mean of refractive error as sphere equivalent, visual acuity and stereopsis were -1.25±1.74 diopters, 0 logMAR, 44.37±13.03 seconds of arc, respectively in photopic light condition while in mesopic light was equal to -1.56±1.75 diopters, 0.12±0.09 logMAR and 50.62±33.35 seconds of arc, respectively. The mean of contrast sensitivity measured at spatial frequencies of 1.5, 3, 6, 12, and 18 cycles per degree in photopic condition was equal to 2.38±0.04, 2.37±0.07, 2.04±0.21, 1.27±0.32, 0.82±0.27 logarithm of contrast sensitivity, respectively and in mesopic lighting condition was equal to 2.34±0.12, 2.30±0.16, 1.84±0.28, 1.02±0.28, 0.63±0.24 logarithm of contrast sensitivity, respectively. Statistical analysis showed a significant difference between the two lighting conditions in all evaluated variables [refractive error (P

Purpose: To evaluate near, intermediate, distance visual acuity and stereopsis after bilateral implantation of Toric intraocular lenses (IOLs) in high myopic patients with astigmatism. Methods: Bilateral Toric or non-Toric IOL implantation (n ​= ​40 eyes each) was performed on high myopic cataract eyes with astigmatism. Best-corrected distance visual acuity (BCDVA), uncorrected intermediate visual acuity (UCIVA), uncorrected near visual acuity (UCNVA), residual refractive astigmatism (RRA), and near, intermediate, and distance stereoacuity were measured postoperatively at 7 days, 1 month, and 3 months. Results: The three-month postoperative BCDVA, UCIVA, and UCNVA of the Toric group were 0.08 ​± ​0.07, 0.30 ​± ​0.11, and 0.23 ​± ​0.14 LogMAR. All improved over the preoperative assessments (P ​ ​0.05). Conclusions: In bilateral high myopic cataract patients with astigmatism, Toric IOLs not only improved UCIVA, UCNVA, and RRA, but also enhanced near and intermediate stereopsis acuity.

Purpose: To report stereopsis after bilateral Yokoyama procedure in patients with highly myopic strabismus and good visual acuity. Observations: Five patients aged between 34 and 81 years with best-corrected visual acuity of 20/25 or better were operated on. The preoperative strabismus angle ranged from esotropia of 35–113 prism diopters (PD) at distance and esotropia of 40–113 PD at near. One patient had left hypotropia of 4 PD and excyclotorsion of 15°, and the other had left hypotropia of 10 PD. Their axial lengths were 27.65–33.07 mm, and the posterior globe dislocation angles were between 123 and 148° on coronal magnetic resonance imaging (MRI). Limitations of abduction were between −1 and −2. All patients complained of diplopia, and none of them showed stereopsis. The Yokoyama procedure was performed on both eyes. Postoperative alternate cover testing showed from esotropia of 2 PD to exophoria of 8 PD at distance and from exotropia of 12 PD to esophoria of 10 PD at near.Three patients recovered stereopsis of 100, 50, and 140 sec, respectively. Two cases required unilateral inferior rectus muscle recessions, and their postoperative stereopsis was 25 and 50 sec. Conclusions and Importance: The Yokoyama procedure is effective not only in cases of heavy eye syndrome but also in cases of myopic esotropia associated with a globe dislocation angle of 120° or with little abduction restriction. If visual acuity is good, stereopsis may be restored with improvement in eye deviation.