Playing three-dimensional video games boosts stereo vision.

Playing two-dimensional video games has been shown to result in improvements in a range of visual and cognitive tasks, and these improvements appear to generalize widely1,2,3,4,5,6. Here we report that young adults with healthy vision, surprisingly, showed a dramatic improvement in stereo vision after playing three-dimensional, but not two-dimensional, video games for a relatively short period of time. Intriguingly, neither group showed any significant improvement in binocular contrast sensitivity. This dissociation suggests that the visual enhancement was specific to genuine stereoscopic processing, not indirectly resulting from enhanced contrast processing, and required engaging in a disparity cue-rich three-dimensional environment.

Visual and Refractive Outcomes After Bi-aspheric Trifocal Toric Diffractive Intraocular Lens Implantation.

PURPOSE: To assess clinical outcomes after cataract surgery with bilateral implantation of a new bi-aspheric diffractive intraocular lens (IOL). METHODS: Thirty patients underwent bilateral implantation of the Asqelio Trifocal Toric IOL (AST Products, Inc) and were evaluated 3 months postoperatively. Main outcomes included refractive error, photopic monocular and binocular uncorrected and corrected distance (UDVA, CDVA), intermediate (UIVA, CDIVA) at 60 cm, and near (UNVA, CDNVA) at 40 cm visual acuities. Mesopic monocular and binocular CDNVA were also measured. Defocus curves, binocular contrast sensitivity under photopic and mesopic conditions with and without glare and rotational stability were determined. Patients completed Catquest-9SF and visual symptoms questionnaires. RESULTS: Average values of binocular photopic CDVA, CDIVA, and CDNVA, and mesopic CDNVA were -0.04 ± 0.06, 0.02 ± 0.08, 0.02 ± 0.07, and 0.22 ± 0.11 logMAR, respectively. All patients achieved cumulative CDVA ⩾ 20/25, and CDIVA and CDNVA of 20/32 or better. Binocular depth of focus was approximately 3.25 diopters (D). Mean postoperative spherical equivalent was -0.08 ± 0.26 D, with 95% of eyes within ±0.50 D. Mean postoperative refractive cylinder was -0.22 ± 0.27 D, with 91.67% of eyes within 0.50 D or less, respectively. IOL rotation averaged 0.25 ± 0.65 degrees, all eyes having rotation of less than 5 degrees. Contrast sensitivity was within or above normal levels under photopic and mesopic conditions, with or without glare, except for 12 cpd under mesopic conditions with glare. Questionnaire responses indicated 96.67% of patients were satisfied or very satisfied with postoperative vision, and 80.00% to 96.67% reported no difficulty in different daily activities. CONCLUSIONS: The Asqelio Trifocal Toric IOL demonstrated favorable outcomes, providing excellent visual performance at all distances, precise refractive results, and remarkable rotational stability. Patients reported high satisfaction levels and minimal difficulty in daily activities. [J Refract Surg. 2024;40(6):e407-e419.].

Clinical Outcomes of a Toric Enhanced Depth-of-Focus Intraocular Lens Based on the Combination of 4th- and 6th-Order Spherical Aberration.

PURPOSE: To assess the visual and refractive outcomes of patients implanted with a toric extended depth-of-focus (EDOF) intraocular lens (IOL) following cataract surgery. METHODS: A total of 44 eyes implanted with the EDOF LuxSmart toric IOL were evaluated 4 to 6 months postoperatively. The main outcomes measurements evaluated were refractive error, rotational stability, distance, intermediate, and near visual acuities, defocus curve, photopic and mesopic contrast sensitivity, wavefront aberrations, and modulation transfer function, and the Catquest-9SF-questionnaire. RESULTS: The mean postoperative spherical equivalent and cylinder were -0.02 ± 0.26 and -0.17 ± 0.29 diopters (D), respectively. A total of 90.45% and 100% of the eyes had a postoperative spherical equivalent within ±0.50 and ±1.00 D, respectively (this being 93.18% and 100% for the refractive cylinder). The mean rotational stability was 0.61 ± 1.61 degrees. The mean binocular corrected distance visual acuity (CDVA), corrected distance intermediate visual acuity (CDIVA), and corrected distance near visual acuity (CDNVA) were -0.02 ± 0.06, 0.07 ± 0.08, and 0.26 ± 0.09 logMAR, respectively. The CDVA was 20/25 or better in 95.45% of patients, CDIVA was 20/25 or better in 72.73%, and CDNVA was 20/40 or better in 72.73%. The defocus curve showed good visual acuity at distance and intermediate vergences. The contrast sensitivity and optical quality outcomes were good with mean higher order, spherical, and coma aberration values of 0.161 ± 0.155, -0.019 ± 0.048, and 0.080 ± 0.065 µm, respectively. A total of 90.9% of patients were either fairly satisfied or very satisfied with their vision after the surgery, and 77.7% of patients reported no difficulties when reading text in newspapers. CONCLUSIONS: Implantation of the toric pure refractive EDOF technology IOL provides good refractive, optical, and visual quality at different distances, with high levels of patient satisfaction being reported. [J Refract Surg. 2024;40(6):e398-e406.].

Collective plasticity of binocular interactions in the adult visual system.

Binocular visual plasticity can be initiated via either bottom-up or top-down mechanisms, but it is unknown if these two forms of adult plasticity can be independently combined. In seven participants with normal binocular vision, sensory eye dominance was assessed using a binocular rivalry task, before and after a period of monocular deprivation and with and without selective attention directed towards one eye. On each trial, participants reported the dominant monocular target and the inter-ocular contrast difference between the stimuli was systematically altered to obtain estimates of ocular dominance. We found that both monocular light- and pattern-deprivation shifted dominance in favour of the deprived eye. However, this shift was completely counteracted if the non-deprived eye's stimulus was selectively attended. These results reveal that shifts in ocular dominance, driven by bottom-up and top-down selection, appear to act independently to regulate the relative contrast gain between the two eyes.

Effect of the chromaticity of stimuli on night vision disturbances.

The perception of halos and other night vision disturbances is a common complaint in clinical practice. Such visual disturbances must be assessed in order to fully characterize each patient's visual performance, which is particularly relevant when carrying out a range of daily tasks. Visual problems are usually assessed using achromatic stimuli, yet the stimuli encountered in daily life have very different chromaticities. Hence, it is important to assess the effect of the chromaticity of visual stimuli on night vision disturbances. The aim of this work is to study the influence of the chromaticity of different visual stimuli on night vision disturbances by analyzing straylight and visual discrimination under low-light conditions. For that, we assessed the monocular and binocular visual discrimination of 27 subjects under low illumination using the Halo test. The subjects' visual discrimination was assessed after exposure to different visual stimuli: achromatic, red, green, and blue, both at the monitor's maximum luminance and maintaining the same luminance value for the different visual stimuli. Monocular straylight was also measured for an achromatic, red, green, and blue stimuli. The blue stimulus had the greatest effect on halos in both monocular and binocular conditions. Visual discrimination was similar for the red, green, and achromatic stimuli, but worsened at lower luminance. The greatest influence of straylight was observed for the blue stimulus. In addition, visual discrimination correlated with straylight measurements for achromatic stimuli, wherein greater straylight values correlated with an increased perception of halos and other visual disturbances.

Effect of 4-week preoperative prism adaptation in preventing postoperative residual esotropia.

BACKGROUND: Preoperative prism adaptation (PPA) simulates postoperative status and possibly can predict postoperative undercorrection before surgery in esotropia. The present study aimed to assess the effect of 4-week PPA in preventing postoperative residual esotropia. METHODS: Seventy-five (75) esotropes who had undergone surgery at a single strabismus center were retrospectively enrolled. They included 25 basic, 31 acute comitant, 10 partially accommodative, and 9 recurrent esotropia patients. The preoperative deviation angle, which had been determined using the alternating prism and cover test, was fully corrected with press-on prisms 4 weeks before surgery. If there was an increase of 5 PD or more of esodeviation, the prisms were changed accordingly at 2 weeks. The deviation angle measured at 4 weeks was determined as the surgical target angle. Patients were then divided into increase (≥ 5 PD increase of angle during 4-week PPA) and non-increase groups. Success was defined as either esodeviation of 8 PD or under or exodeviation of 5 PD or under at distance at postoperative 6 months. RESULTS: The increase group included 44 patients (58.7%). The mean deviation angle before PPA was 27.4 PD, and after the 4-week PPA, there was an average increase of 9.4 PD. The success rate was 90.9% in the increase group and 96.8% in the non-increase group (p = 0.316). There were no intergroup differences in preoperative clinical characteristics, esotropia types, postoperative deviation angle or postoperative near stereopsis (p > 0.05). CONCLUSIONS: The results of this study indicated a beneficial effect of 4-week PPA in esotropia of various types, specifically by uncovering the hidden esodeviation in the increase group and simulating the postoperative alignment in both the increase and the non-increase groups.

Continuous psychophysics shows millisecond-scale visual processing delays are faithfully preserved in movement dynamics.

Image differences between the eyes can cause interocular discrepancies in the speed of visual processing. Millisecond-scale differences in visual processing speed can cause dramatic misperceptions of the depth and three-dimensional direction of moving objects. Here, we develop a monocular and binocular continuous target-tracking psychophysics paradigm that can quantify such tiny differences in visual processing speed. Human observers continuously tracked a target undergoing Brownian motion with a range of luminance levels in each eye. Suitable analyses recover the time course of the visuomotor response in each condition, the dependence of visual processing speed on luminance level, and the temporal evolution of processing differences between the eyes. Importantly, using a direct within-observer comparison, we show that continuous target-tracking and traditional forced-choice psychophysical methods provide estimates of interocular delays that agree on average to within a fraction of a millisecond. Thus, visual processing delays are preserved in the movement dynamics of the hand. Finally, we show analytically, and partially confirm experimentally, that differences between the temporal impulse response functions in the two eyes predict how lateral target motion causes misperceptions of motion in depth and associated tracking responses. Because continuous target tracking can accurately recover millisecond-scale differences in visual processing speed and has multiple advantages over traditional psychophysics, it should facilitate the study of temporal processing in the future.

Long-term visual and neurodevelopmental outcomes in children with Congenital Zika Syndrome after undergoing strabismus surgery.

Purpose: To assess long-term visual and neurodevelopmental outcomes in children with congenital Zika syndrome (CZS) after strabismus surgery. Methods: A consecutive sample of five children with CZS who underwent strabismus surgery was enrolled. All children underwent a standardized pre- and postoperative protocol including binocular best-corrected visual acuity (BCVA) using the Teller Acuity Cards II (TAC II), ocular alignment, functional vision using the functional vision developmental milestones test (FVDMT), and neurodevelopmental milestone evaluation using the Bayley Scales of Infant Development-Third Edition (BSID-III). Scores of the FVDMT outcomes considering the child's developmental age based on the BSID-III score were compared with scores from postoperative assessment. Results: Five children with CZS (3 girls, 2 boys) were enrolled with a mean age at baseline (preoperative) of 35.0 ± 0.7 months (range, 34-36 months) and at final assessment of 64.4 ± 0.5 months (range, 64-65 months). Preoperative BCVA was 1.2 ± 0.5 logMAR and at final assessment 0.7 ± 0.1 logMAR. Successful strabismus surgery outcome was maintained in 4/5 (80.0%) of children at final assessment. The children's BSID-III scores showed significant neurodevelopment delay at the initial assessment (corresponding developmental mean age was 4.7 months) and at their final assessment (corresponding developmental mean age was 5.1 months). There was improvement or stability in 34/46 items evaluated in the FVDMT (73.9%) when comparing baseline with 2-year follow-up. Conclusions: Strabismus surgery resulted in long-term ocular alignment in the majority of children with CZS. All the children showed improvement or stability in more than 70.0% of the functional vision items assessed. Visual and neurodevelopmental dysfunction may be related to complex condition and associated disorders seen in CZS including ocular, neurological, and skeletal abnormalities.

Binocular receptive-field construction in the primary visual cortex.

ON and OFF thalamic afferents from the two eyes converge in the primary visual cortex to form binocular receptive fields. The receptive fields need to be diverse to sample our visual world but also similar across eyes to achieve binocular fusion. It is currently unknown how the cortex balances these competing needs between receptive-field diversity and similarity. Our results demonstrate that receptive fields in the cat visual cortex are binocularly matched with exquisite precision for retinotopy, orientation/direction preference, orientation/direction selectivity, response latency, and ON-OFF polarity/structure. Specifically, the average binocular mismatches in retinotopy and ON-OFF structure are tightly restricted to 1/20 and 1/5 of the average receptive-field size but are still large enough to generate all types of binocular disparity tuning. Based on these results, we conclude that cortical receptive fields are binocularly matched with the high precision needed to facilitate binocular fusion while allowing restricted mismatches to process visual depth.

Novel superior oblique anterior fiber plication with or without adjustable sliding knot for extorsion.

PURPOSE: To report a novel surgical technique to correct excyclotropia, consisting of a superior oblique anterior fibers plication (SOAFP) with or without a hemihangback anterior knot, allowing access for postoperative adjustment. METHODS: A retrospective interventional case series was conducted. Fourteen patients, 21-92 years of age, underwent SOAFP (18 eyes, 14 eyes on adjustable), at the Mayo Clinic in Rochester, Minnesota. SOAFP was the only procedure performed in 12 eyes; in 6 it was performed in conjunction with up to four horizontal rectus muscle recession, resection, and/or plication. Ocular alignment was assessed with prism and alternate cover and double Maddox rod tests; preoperatively, at initial and final (closest to 6-8 weeks) postoperative visits. RESULTS: Preoperative torsion ranged from 2° to 30° of extorsion (mean, 10.14 ± 7.01). A SOAFP of 2-30 mm (mean, 8.93 ± 5.63) was performed. At the initial postoperative examination, mean intorsional shift was 11.18 ± 7.37, accounting for 1.86° ± 1.04° of correction per millimeter of plication. Three eyes were adjusted after the initial visit to obtain a stronger plication effect targeting of 5° intorsion. At the final visit, 61 ± 23 days postoperatively, mean extorsion was 1.21° ± 2.29°, ranging from 5° of extorsion to 3 of intorsion. Mean final intorsional shift was 9.14 ± 7.53°, accounting for a 1.16 ± 0.50° of correction per millimeter of plication. Of our 14 patients, 13 had improvement in diplopia. CONCLUSIONS: In our study cohort, SOAFP allowed for targeted and easily adjustable correction of extorsion.

Multisensory-inspired modeling and neural correlates for two key binocular interactions.

Most binocular vision models assume that the two eyes sum incompletely. However, some facilitatory cortical neurons fire for only one eye, but amplify their firing rates if both eyes are stimulated. These 'binocular gate' neurons closely resemble subthreshold multisensory neurons. Binocular amplification for binocular gate neurons follows a power law, with a compressive exponent. Unexpectedly, this rule also applies to facilitatory true binocular neurons; although driven by either eye, binocular neurons are well modeled as gated amplifiers of their strongest monocular response, if both eyes are stimulated. Psychophysical data follows the same power law as the neural data, with a similar exponent; binocular contrast sensitivity can be modeled as a gated amplification of the more sensitive eye. These results resemble gated amplification phenomena in multisensory integration, and other non-driving modulatory interactions that affect sensory processing. Models of incomplete summation seem unnecessary for V1 facilitatory neurons or contrast sensitivity. However, binocular combination of clearly visible monocular stimuli follows Schrödinger's nonlinear magnitude-weighted average. We find that putatively suppressive binocular neurons closely follow Schrödinger's equation. Similar suppressive multisensory neurons are well documented but seldom studied. Facilitatory binocular neurons and mildly suppressive binocular neurons are likely neural correlates of binocular sensitivity and binocular appearance respectively.

Doses of medial rectus muscle recessions for divergence insufficiency-type esotropia.

We evaluated whether doses of bilateral medial rectus recessions greater than Parks's tables yielded superior outcomes for adult-onset divergence insufficiency. Forty-two patients underwent bilateral medial rectus recessions. Dose was analyzed as the average total per muscle (surgery + suture adjustment if performed) and compared with the standard dose tables (based on preoperative distance esodeviation), as difference between dose performed and dose indicated by Parks's tables. Each participant was classified as having received either Parks's dose (within 0.5 mm) or a dose greater than Parks's dose. Success was defined as "rarely" or "never" diplopia in distance straight-ahead gaze and reading. For patients classified as success, the mean difference between actual surgical dose performed and Parks's dose was calculated. Success was 91% (29/32) in those receiving greater than Parks's dose versus 67% (6/9) with Parks's dose (difference = 24%; 95% CI, -5% to 60%). The mean surgical dose was 1.0 mm greater than Parks's tables for the 35 successes (at 10 weeks) versus 0.7 mm greater for the 6 failures (difference = 0.4 mm; 95% CI, -0.2 to 0.9). For medial rectus recessions in adult-onset divergence insufficiency-type esotropia, a surgical dose 1 mm greater than Parks's tables, for each muscle, is a reasonable strategy.

Tolerance to refractive error with a new extended depth of focus intraocular lens.

PURPOSE: To evaluate the tolerance to refractive errors of a new purely refractive extended depth of focus (EDF) intraocular lens (IOL) using preclinical and clinical metrics. METHODS: Preclinical evaluation included computer simulations of visual acuity (sVA) and dysphotopsia profile of different IOL designs (refractive EDF, diffractive EDF, multifocal, standard, and enhanced monofocals) using an appropriate eye model with and without ±0.50 D defocus and/or +0.75 D of astigmatism. Patients bilaterally implanted with a refractive EDF (Model ZEN00V) or an enhanced monofocal (Model ICB00) IOL from a prospective, randomized study were included. At the 6-month postoperative visit, uncorrected and corrected distance vision (UDVA and CDVA), visual symptoms, satisfaction and dependency on glasses were evaluated in a subgroup of patients with absolute residual refractive error of >0.25 D in one or both eyes. RESULTS: In the presence of defocus and astigmatism, sVA was comparable for all except the multifocal IOL design. The refractive EDF was more tolerant to myopic outcomes and maintained a monofocal-like dysphotopsia profile with defocus. Binocular logMAR UDVA was -0.03 ± 0.08 for ZEN00V and -0.02 ± 0.11 for ICB00. 100% ZEN00V and 97% ICB00 patients did not need glasses and were satisfied with their distance vision. Monocular CDVA, contrast sensitivity and visual symptoms were also similar between both groups. CONCLUSIONS: The clinical outcomes of the refractive EDF IOL demonstrated high quality distance vision and dysphotopsia comparable to a monofocal IOL, even in the presence of refractive error, thus matching the design expectations of the EDF IOL.

Peripheral Binocular Imbalance in Anisometropic and Strabismic Amblyopia.

Purpose: Individuals with amblyopia experience central vision deficits, including loss of visual acuity, binocular vision, and stereopsis. In this study, we examine the differences in peripheral binocular imbalance in children with anisometropic amblyopia, strabismic amblyopia, and typical binocular vision to determine if there are systematic patterns of deficits across the visual field. Methods: This prospective cohort study recruited 12 participants with anisometropic amblyopia, 10 with strabismic amblyopia, and 10 typically sighted controls (age range, 5-18 years). Binocular imbalance was tested at 0°, 4°, and 8° eccentricities (4 angular locations each) using band-pass filtered Auckland optotypes (5 cycles per optotype) dichoptically presented with differing contrast to each eye. The interocular contrast ratio was adjusted until the participant reported each optotype with equal frequency. Results: Participants with anisometropic and strabismic amblyopia had a more balanced contrast ratio, or decreased binocular imbalance, at 4° and 8° eccentricities as compared with central vision. Participants with strabismic amblyopia had significantly more binocular imbalance in the periphery as compared with individuals with anisometropic amblyopia or controls. A linear mixed effects model showed a main effect for strabismic amblyopia and eccentricity on binocular imbalance across the visual field. Conclusions: There is evidence of decreased binocularity deficits, or interocular suppression, in the periphery in anisometropic and strabismic amblyopia as compared with controls. Notably, those with strabismic amblyopia exhibited more significant peripheral binocular imbalance. These variations in binocularity across the visual field among different amblyopia subtypes may necessitate tailored approaches for dichoptic treatment.

Comparison of Two Presbyopia-Correcting Trifocal Intraocular Lenses: A Prospective Study.

Objectives: To evaluate the clinical results of a new trifocal intraocular lens (IOL) with sinusoidal design by comparing with a traditional trifocal IOL. Materials and Methods: A total of 79 patients undergoing uneventful microincisional cataract surgery with bilateral implantation of one of two types of trifocal IOLs, the Acriva Trinova IOL (VSY) or Acrysof IQ PanOptix IOL (Alcon), were enrolled in this prospective study. Visual and refractive outcomes, contrast sensitivity (CS), and defocus curve were assessed at 3 months after surgery. Patient satisfaction and incidence of photic phenomena were also evaluated. Results: The number of patients/eyes were 48/96 in the Trinova group and 31/62 in the PanOptix group. There were no significant differences between the groups for monocular and binocular corrected/uncorrected distance or intermediate (at 60 cm) and near visual acuities (VA) postoperatively. The Trinova group had statistically significantly better intermediate VA at 80 cm than the PanOptix group (p<0.05). The CS results of both groups were within the normal limits. In the binocular defocus curve of both IOLs, we observed a peak of good VA at 0.0 diopters defocus and a useful wide range for intermediate distances. The incidence of photic phenomena in the Trinova group was lower at postoperative 1 month (p<0.05) but this difference disappeared at 3 months. A total of 47 patients (97.9%) in the Trinova group and 30 patients (96.7%) in the PanOptix group stated that they would recommend the same IOL. Conclusion: Both trifocal IOLs provide good visual quality outcomes and patient satisfaction.

Extraction of three-dimensional shapes in glaucoma patients in response to monocular depth cues.

PURPOSE: To assess the impact of glaucoma on perceiving three-dimensional (3D) shapes based on monocular depth cues. STUDY DESIGN: Clinical observational study. METHODS: Twenty glaucoma patients, subjected to binocular visual-field sensitivity (binocular-VFS) tests using a Humphrey Visual Field Analyzer, and 20 age-matched healthy volunteers, underwent two tasks: identifying the nearest vertex of a 3D shape using monocular shading (3D-SfS), texture (3D-SfT), or motion (3D-SfM) cues, and distinguishing elementary one-dimensional (1D) features of these cues. The association of the visual-field index (VFI) of binocular-VFS with 3D shape perception in glaucoma patients was also examined. RESULTS: Glaucoma patients demonstrated reduced accuracy in distinguishing 1D luminance brightness and a larger "error-in-depth" between the perceived and actual depths for 3D-SfM and 3D-SfS compared to healthy volunteers. Six glaucoma patients with a 100% VFI for binocular-VFS exhibited a similar error-in-depth to the other fourteen glaucoma patients; they had a larger error-in-depth for 3D-SfM compared to healthy volunteers. No correlation between the error-in-depth values and the VFI values of binocular-VFS was observed. CONCLUSIONS: The 3D shape perception in glaucoma patients varies based on the depth cue's characteristics. Impaired 1D discrimination and larger thresholds for 3D-SfM in glaucoma patients with a 100% VFI for binocular-VFS indicate more pronounced perceptual deficits of lower-level elementary features for 3D-SfS and higher-level visual processing of 3D shapes for 3D-SfM. The effects of the location and degree of binocular visual-field defects on 3D shape perception remain to be elucidated. Our research provides insights into the 3D shape extraction mechanism in glaucoma.

Stereoscopic slant contrast revisited.

The perceived slant of a stereoscopic surface is altered by the presence of a surrounding surface, a phenomenon termed stereo slant contrast. Previous studies have shown that a slanted surround causes a fronto-parallel surface to appear slanted in the opposite direction, an instance of "bidirectional" contrast. A few studies have examined slant contrast using slanted as opposed to fronto-parallel test surfaces, and these also have shown slant contrast. Here, we use a matching method to examine slant contrast over a wide range of combinations of surround and test slants, one aim being to determine whether stereo slant contrast transfers across opposite directions of test and surround slant. We also examine the effect of the test on the perceived slant of the surround. Test slant contrast was found to be bidirectional in virtually all test-surround combinations and transferred across opposite test and surround slants, with little or no decline in magnitude as the test-surround slant difference approached the limit. There was a weak bidirectional effect of the test slant on the perceived slant of the surround. We consider how our results might be explained by four mechanisms: (a) normalization of stereo slant to vertical; (b) divisive normalization of stereo slant channels in a manner analogous to the tilt illusion; (c) interactions between center and surround disparity-gradient detectors; and (d) uncertainty in slant estimation. We conclude that the third of these (interactions between center and surround disparity-gradient detectors) is the most likely cause of stereo slant contrast.

The relationship between accommodative and binocular function with myopia progression in myopic children undergoing orthokeratology.

PURPOSE: To determine the relationship between changes in accommodative and binocular function with myopia progression in myopic children over a two-year follow-up period, and to determine when changes in visual functions stabilized after switching from spectacles to orthokeratology (Ortho-K). METHODS: This prospective, self-controlled study followed thirty-six participants (aged 8-14 years) for two years after they switched from spectacles to Ortho-K. Accommodative and binocular function were assessed prior to and 1, 3, 6, 12, 18 and 24 months after commencing Ortho-K. Measurements included accommodative amplitude, accommodative response, accommodative facility, accommodative convergence/accommodation (AC/A), ocular alignment, positive relative accommodation (PRA), negative relative accommodation (NRA), horizontal vergence range, reading ability and stereoacuity. Myopia progression was quantified by the change in axial length. RESULTS: Ocular alignment, monocular and binocular accommodative facility, and PRA stabilized after 1 month. The distance blur point in the convergence range, the distance break and recovery point in the divergence range, accommodative amplitude, calculated AC/A, stereoacuity and reading ability stabilized within 6 months. After two years of Ortho-K, NRA significantly increased (p = 0.044), while it showed no significant difference after one-year of lens wear (p = 0.49). The distance break point in the convergence range showed no significant difference (p = 0.20), but significantly decreased after one-year (p = 0.005). There were no significant correlations between the change in axial length with changes in accommodative or binocular function (p > 0.05). CONCLUSION: Accommodative and binocular function changed significantly after switching from spectacles to Ortho-K and most of the parameters stabilized within the first 6 months. There was no association between the change in accommodative or binocular function and myopia progression.

Surround masking reveals binocular adding and differencing channels.

Recent studies suggest that binocular adding S+ and differencing S- channels play an important role in binocular vision. To test for such a role in the context of binocular contrast detection and binocular summation, we employed a surround masking paradigm consisting of a central target disk surrounded by a mask annulus. All stimuli were horizontally oriented 0.5c/d sinusoidal gratings. Correlated stimuli were identical in interocular spatial phase while anticorrelated stimuli were opposite in interocular spatial phase. There were four target conditions: monocular left eye, monocular right eye, binocular correlated and binocular anticorrelated, and three surround mask conditions: no surround, binocularly correlated and binocularly anticorrelated. We observed consistent elevation of detection thresholds for monocular and binocular targets across the two binocular surround mask conditions. In addition, we found an interaction between the type of surround and the type of binocular target: both detection and summation were relatively enhanced by surround masks and targets with opposite interocular phase relationships and reduced by surround masks and targets with the same interocular phase relationships. The data were reasonably well accounted for by a model of binocular combination termed MAX (S+S-), in which the decision variable is the probability summation of modeled S+ and S- channel responses, with a free parameter determining the relative gains of the two channels. Our results support the existence of two channels involved in binocular combination, S+ and S-, whose relative gains are adjustable by surround context.

The role of pattern coherence in interocular grouping during binocular rivalry: Insights from individual differences.

Interocular grouping during binocular rivalry occurs when two images presented to each eye combine into a coherent pattern. The experience of interocular grouping is thought to be influenced by both eye-of-origin, which involves excitatory lateral connections among monocular neurons, and pattern coherence, which results from top-down intervention from higher visual areas. However, it remains unclear which factor plays a more significant role in the interocularly-grouped percepts during binocular rivalry. The current study employed an individual difference approach to investigate whether grouping dynamics are mainly determined by eye-of-origin or pattern coherence. We found that participants who perceived interocularly-driven coherent percepts for a longer duration also tended to experience longer periods of monocularly-driven coherent percepts. In contrast, participants who experienced non-coherent piecemeal percepts for an extended duration in conventional rivalry also had longer duration of non-coherent percepts in the interocular coherence setting. This individual differences in experiencing interocular grouping suggest that pattern coherence exerts a stronger influence on grouping dynamics during binocular rivalry compared to eye-of-origin factors.