[Outcomes of extended depth of focus intraocular lenses implantation]. / Rezul'tat implantatsii intraokulyarnykh linz s rasshirennoi glubinoi fokusa.

Extended depth of focus (EDOF) intraocular lenses (IOLs) are the latest IOL designs. In recent years, several models of EDOF IOLs have become available in Russia, two of which (Tecnis Symfony and Acrysof IQ Vivity) are implanted in our clinic. Comparative studies devoted to the results of implantation of the new EDOF IOLs are rare in the available literature. PURPOSE: This article compares the outcomes of implantation of two EDOF IOLs in patients with presbyopia and/or cataract. MATERIAL AND METHODS: The prospective study included 60 patients (81 eyes) after implantation of EDOF IOL Tecnis Symfony (32 patients, 45 eyes; group 1) or EDOF IOL AcrySof IQ Vivity (28 patients, 36 eyes; group 2). The mean follow-up period was 3.9±1.3 months. RESULTS: All groups showed a significant (p<0.05) increase in uncorrected near visual acuity (UCNVA), intermediate visual acuity (UCIVA), and distance visual acuity (UCDVA) at the maximum follow-up time compared to preoperative values. In group 1, the best corrected near visual acuity (BCNVA) increased from 0.61±0.10 to 0.82±0.16 at the maximum follow-up time, and in group 2 - from 0.58±0.08 to 0.67±0.12 (p>0.05). Both groups showed a significant increase in best corrected intermediate and distance visual acuity (BCIVA and BCDVA) at the maximum follow-up time. The increase in the indicator compared to the preoperative period was not significant in both groups (p>0.05). The frequency of side optical phenomena was low in both groups. No significant differences were found between the groups (p>0.05). CONCLUSION: This study presents a comparative analysis of the results of implantation of two different EDOF IOLs. Both lenses were comparable in most of the studied parameters, including providing good distance and intermediate vision, functional near vision, as well as a low frequency of side optical phenomena. In all cases the patients were satisfied with the results of the surgical intervention.

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.

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.

Extended depth of focus IOL in eyes with different axial myopia and targeted refraction.

AIM: To evaluate the objective visual outcomes following implantation of extended depth of focus intraocular lens (EDOF IOL) in individuals with varying axial lengths (AL) and targeted refraction. METHODS: This retrospective study comprised age-matched eyes that underwent implantation of the EDOF IOL. Eyes were categorized based on AL into groups: control group with AL < 26 mm; high myopia group with AL ≥ 26 mm. Each group was then subdivided based on postoperative spherical equivalent (SE). Follow-up at three months included assessment of uncorrected visual acuity at different distances, contrast sensitivity (CS), refractive outcomes, and spectacle independence. RESULTS: Overall, this study included 100 eyes from 100 patients, comprising 50 males (50.00%) and 50 females (50.00%), with 20 eyes in each group. In the control group, the uncorrected distance visual acuity (UDVA) at 5 and 3 m (m) in the - 1.50 to -0.75 group was inferior to that of the - 0.75 to 0.00 group (P = 0.004). Conversely, the uncorrected near visual acuity (UNVA) at 33 cm in the - 1.50 to -0.75 group was superior to that of the - 0.75 to 0.00 group (P = 0.005). Within the high myopia group, the UDVA at 5 and 3 m in the - 2.25 to -1.50 group was worse than in the - 0.75 to 0.00 group (P = 0.009 and 0.008, respectively). However, the UNVA at 33 cm in the - 2.25 to -1.50 group was better than in the - 0.75 to 0.00 group (P = 0.020). No significant differences were observed among the groups for corrected distance visual acuity (CDVA) (P > 0.05). Additionally, in the high myopia group, the CS of the - 2.25 to -1.50 group was lower compared to that of the - 0.75 to 0.00 group (P = 0.017). Among high myopia patients, 90.00% with refraction ranging from - 1.50 to -0.75 reported achieving overall spectacle independence. CONCLUSIONS: Implantation of extended depth of focus intraocular lenses (IOLs) yields satisfactory visual and refractive outcomes in eyes with axial myopia. Among high myopia patients, a refraction ranging from - 1.50 to -0.75 diopters achieves superior visual quality compared to other postoperative myopic diopters.

Real-World Clinical Results with the Hoya Vivinex Impress Intraocular Lens with Enhanced Depth of Focus.

BACKGROUND: In cataract surgery, intraocular lenses (IOLs) with enhanced depth of focus are an option to correct presbyopia. The purpose of this quality assurance analysis was to evaluate visual acuity and patient satisfaction after implantation of the Hoya Vivinex Impress IOL. METHODS: The Hoya Vivinex Impress IOL was implanted in patients undergoing cataract surgery at the Pallas Klinik, Olten, Switzerland. Five weeks postoperatively, a clinical examination and a survey on patient satisfaction were conducted. RESULTS: A total of 17 eyes (9 patients; mean age 64 years) underwent cataract surgery with implantation of a Hoya Vivinex Impress IOL. Five weeks postoperatively, mean uncorrected distance visual acuity (UDVA) was 0.2 logMAR, uncorrected intermediate visual acuity (UIVA) was 0.0 logMAR, and uncorrected near visual acuity (UNVA) was 0.2 logMAR. The mean distance-corrected visual acuity results were 0.0 logMAR, 0.1 logMAR, and 0.3 logMAR, respectively. Reading the newspaper without glasses was possible for 33.4% of patients. Visual disturbances such as halos and glares were not reported. CONCLUSION: Cataract surgery with Hoya Vivinex Impress IOL implantation revealed good distance and intermediate vision and, in some patients, functional near vision as well as a high patient satisfaction.

Patient-Reported Outcome Measures (PROMs) with Refractive and Diffractive Extended Depth of Focus (EDOF) Intraocular Lenses.

BACKGROUND: Extended depth of focus intraocular lenses (EDOF-IOLs) provide unaided far- and mid-range vision. Refractive IOLs, in contrast to diffractive designs, are associated with a lower depth of focus and absence of dysphotopsia. The aim of this study was to assess spectacle independence for far-range, mid-range, and near-vision activities in patients after implantation of refractive or diffractive EDOF-IOLs using patient-reported outcome measures (PROMs) in a real-world setting. PATIENTS AND METHODS: In 2021 and 2022, all patients in a single center referred for bilateral cataract surgery were assigned to 7 experienced cataract surgeons who either bilaterally implanted only a diffractive EDOF-IOL (Carl Zeiss Meditec AG, AT LARA Jena, Germany, three surgeons) or refractive EDOF-IOL (Johnson & Johnson Vision Inc., Tecnis Eyhance Irvine, California, USA, four surgeons) at the surgeon's discretion, with the aim of bilateral emmetropia. Six months after both cataract surgeries, all patients were contacted by telephone and asked to report their outcomes using a structured questionnaire investigating their spectacle usage for various daily activities and their experience with night glare or halos. Inclusion criteria were a normal postoperative visual potential based on the preoperative examination and completion of the questionnaire regarding postoperative visual experience. RESULTS: Of the patients, 514 underwent bilateral cataract surgery aiming for bilateral emmetropia with the implantation of EDOF-IOLs (422 with Tecnis Eyhance and 92 with AT LARA). A complete questionnaire was obtained from 472 (92%) patients, who were included in the study (393 vs. 79). Comparing Tecnis Eyhance with AT LARA IOL, 54 vs. 57% patients were able to perform most of their daily activities without spectacles, 9 vs. 19% reported not being dependent on spectacles at all, 25 vs. 29% reported using their smartphones without spectacles, 15 vs. 49% patients reported experiencing glares or halos at night, and 1 vs.15% with driving disturbance. Overall, 95 vs. 93% patients described themselves as "satisfied" or "highly satisfied" with their IOL. CONCLUSIONS: With both types of EDOF-IOLs, the majority of patients could perform most of their daily activities without spectacles, except reading, and were highly satisfied with their IOLs. Patients with diffractive Zeiss AT LARA EDOF-IOLs were more likely to accomplish unaided near-range visual tasks; however, they were also at a higher risk of experiencing glares or halos at night.

Toward a theory of perspective perception in pictures.

This paper reviews projection models and their perception in realistic pictures, and proposes hypotheses for three-dimensional (3D) shape and space perception in pictures. In these hypotheses, eye fixations, and foveal vision play a central role. Many past theories and experimental studies focus solely on linear perspective. Yet, these theories fail to explain many important perceptual phenomena, including the effectiveness of nonlinear projections. Indeed, few classical paintings strictly obey linear perspective, nor do the best distortion-avoidance techniques for wide-angle computational photography. The hypotheses here employ a two-stage model for 3D human vision. When viewing a picture, the first stage perceives 3D shape for the current gaze. Each fixation has its own perspective projection, but, owing to the nature of foveal and peripheral vision, shape information is obtained primarily for a small region of the picture around the fixation. As a viewer moves their eyes, the second stage continually integrates some of the per-gaze information into an overall interpretation of a picture. The interpretation need not be geometrically stable or consistent over time. It is argued that this framework could explain many disparate pictorial phenomena, including different projection styles throughout art history and computational photography, while being consistent with the constraints of human 3D vision. The paper reviews open questions and suggests new studies to explore these hypotheses.

Quantifying the Relationship Between Unilateral Induced Metamorphopsia and Stereopsis Impairment.

Purpose: To investigate the relationship between unilateral metamorphopsia, characterized by visual distortions in one eye, and impaired stereopsis. Methods: Utilizing both near and distance measurements through advanced testing systems, including 4K smartphones and an active shutter three-dimensional system, we simulated varying degrees of unilateral metamorphopsia in 30 healthy young adults aged between 21 and 29 years. Two types of contour-based stereotest symbols, lines and squares, were developed. Distortions were classified into six distinct patterns, each further divided into eight grades of severity. Participants were tasked with identifying visual targets, and their stereothresholds were determined under different conditions of induced distortion. Stereopsis was measured within a range of 2.9 to 1.0 log arcsec, at 0.2 log arcsec intervals. Stereopsis changes under different distortion scenarios were analyzed using the generalized estimating equations, with a sequential Bonferroni adjustment applied for pairwise comparisons. Results: A direct and quantifiable correlation was observed between the severity of metamorphopsia and reductions in stereopsis. As the degree of visual distortion increased, notably in both frequency and amplitude, there was a corresponding decline in stereopsis. This relationship held true in both near and distance measurements of stereopsis. Statistical analyses further reinforced these findings, highlighting a significant detrimental effect of distortion components on stereoacuity. Conclusions: The findings highlight the clinical significance of understanding the interplay between unilateral metamorphopsia and stereopsis. Early interventions in conditions leading to metamorphopsia might be critical to maintaining optimal stereopsis.

Wearable apparatus for correction of visual alignment under torsional strabismus.

SIGNIFICANCE: A wearable optical apparatus that compensates for eye misalignment (strabismus) to correct for double vision (diplopia) is proposed. In contrast to prism lenses, commonly used to compensate for horizontal and/or vertical misalignment, the proposed approach is able to compensate for any combination of horizontal, vertical, and torsional misalignment. PURPOSE: If the action of the extraocular muscles is compromised (e.g., by nerve damage), a patient may lose their ability to maintain visual alignment, negatively affecting their binocular fusion and stereo depth perception capability. Torsional misalignment cannot be mitigated by standard Fresnel prism lenses. Surgical procedures intended to correct torsional misalignment may be unpredictable. A wearable device able to rectify visual alignment and restore stereo depth perception without surgical intervention could potentially be of great value to people with strabismus. METHODS: We propose a novel lightweight wearable optical device for visual alignment correction. The device comprises two mirrors and a Fresnel prism, arranged in such a way that together they rotationally shift the view seen by the affected eye horizontally, vertically, and torsionally. The extent of the alignment correction on each axis can be arbitrarily adjusted according to the patient's particular misalignment characteristics. RESULTS: The proposed approach was tested by computer simulation, and a prototype device was manufactured. The prototype device was tested by a strabismus patient exhibiting horizontal and torsional misalignment. In these tests, the device was found to function as intended, allowing the patient to enjoy binocular fusion and stereo depth perception while wearing the device for daily activities over a period of several months. CONCLUSIONS: The proposed device is effective in correcting arbitrary horizontal, vertical, and torsional misalignment of the eyes. The results of the initial testing performed are highly encouraging. Future study is warranted to formally assess the effectiveness of the device on multiple test patients.

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.

Quality of vision clinical outcomes for a new fully-refractive extended depth of focus Intraocular Lens.

BACKGROUND/OBJECTIVE: To evaluate the visual performance of a purely refractive extended depth of focus (EDF) intraocular lens (IOL). SUBJECTS/METHODS: A prospective, multi-center, randomized, subject/evaluator-masked study. Subjects were bilaterally implanted with the EDF test (Model ZEN00V, N = 60) or an enhanced monofocal control (Model ICB00, N = 57) IOL. Monocular corrected distance (CDVA), intermediate (DCIVA), near acuities (DCNVA) and patient reported visual symptoms were evaluated at the 6-month visit. Monocular mesopic contrast sensitivity (CS) and depth of focus (DOF) testing were assessed at 3 months. RESULTS: CDVA (Mean ± SD) was -0.06 ± 0.08 for test and -0.05 ± 0.08 logMAR for control groups. DCIVA was 0.13 ± 0.08 for test and 0.18 ± 0.14 logMAR for control groups (p = 0.0127). DCNVA was 0.37 ± 0.10 for test and 0.43 ± 0.16 logMAR for control groups (p = 0.0137). Test lens was statistically superior for intermediate and near. Overall, 91.7% (halos), 95.0% (starbursts) and 95.0% (glare) of test lens patients reported that they did not experience, were not bothered, or were slightly bothered by specific visual symptoms, compared to 98.2%, 100% and 96.5% in the control group. The DOF range over which monocular visual acuity was 0.20 logMAR or better was -1.6 D for the test lens. Mesopic CS was comparable between both groups, falling within 0.11 log units for all measured cycles per degree with and without glare. CONCLUSION: The EDF IOL demonstrated extended range of vision and statistically superior intermediate and near performance compared to the monofocal IOL. Distance visual acuity, contrast sensitivity and dysphotopsia profile were similar to the monofocal IOL.

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.

Optical and clinical simulated performance of a new refractive extended depth of focus intraocular lens.

OBJECTIVES: The purpose of this study is to evaluate the optical and expected clinical performance of a new refractive Extended Depth of Focus (EDF) intraocular lens (IOL) designed to maintain a monofocal-like dysphotopsia profile. METHODS: Simulated visual acuity (sVA) with varying defocus was calculated using the area under the Modulation Transfer Function measured in an average eye model and from computer simulations in eye models with corneal higher-order aberrations. Tolerance to defocus was evaluated using computer simulations of the uncorrected distance sVA under defocus. To evaluate the dysphotopsia profile, halo pictures obtained using an IOL-telescope, as well as simulated images in a realistic eye model under defocus were assessed. The results of the refractive EDF were compared to those of a diffractive EDF of the same platform. RESULTS: The refractive EDF IOL provides similar range of vision to the diffractive EDF IOL with the same distance, and similar intermediate and near sVA. The refractive EDF IOL provides the same tolerance to hyperopia as the diffractive EDF but more tolerance to myopia. Halo pictures and simulations showed that the refractive EDF provides comparable dysphotopsia profile to the monofocal IOL and better than the diffractive EDF. CONCLUSIONS: The results of this preclinical study in clinically relevant conditions show that the new refractive EDF IOL is expected to provide similar range of vision to the diffractive IOL of the same platform and higher tolerance to refractive errors. The refractive EDF provides a dysphotopsia profile that is better than the diffractive EDF and comparable to that of the monofocal IOL, also in the presence of residual refractive errors.

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.

Perception of visual and audiovisual trajectories toward and away from the body in the first postnatal year.

Perceiving motion in depth is important in everyday life, especially motion in relation to the body. Visual and auditory cues inform us about motion in space when presented in isolation from each other, but the most comprehensive information is obtained through the combination of both of these cues. We traced the development of infants' ability to discriminate between visual motion trajectories across peripersonal space and to match these with auditory cues specifying the same peripersonal motion. We measured 5-month-old (n = 20) and 9-month-old (n = 20) infants' visual preferences for visual motion toward or away from their body (presented simultaneously and side by side) across three conditions: (a) visual displays presented alone, (b) paired with a sound increasing in intensity, and (c) paired with a sound decreasing in intensity. Both groups preferred approaching motion in the visual-only condition. When the visual displays were paired with a sound increasing in intensity, neither group showed a visual preference. When a sound decreasing in intensity was played instead, the 5-month-olds preferred the receding (spatiotemporally congruent) visual stimulus, whereas the 9-month-olds preferred the approaching (spatiotemporally incongruent) visual stimulus. We speculate that in the approaching sound condition, the behavioral salience of the sound could have led infants to focus on the auditory information alone, in order to prepare a motor response, and to neglect the visual stimuli. In the receding sound condition, instead, the difference in response patterns in the two groups may have been driven by infants' emerging motor abilities and their developing predictive processing mechanisms supporting and influencing each other.

Mean orientation discrimination based on proximal stimuli.

Ensemble perception refers to the ability to accurately and rapidly perceive summary statistical representations of specific features from a group of similar objects. However, the specific type of representation involved in this perception within a three-dimensional (3-D) environment remains unclear. In the context of perspective viewing with stereopsis, distal stimuli can be projected onto the retina as different forms of proximal stimuli based on their distances, despite sharing similar properties, such as object size and spatial frequency. This study aimed to investigate the effects of distal and proximal stimuli on the perception of summary statistical information related to orientation. In our experiment, we presented multiple Gabor patches in a stereoscopic environment, allowing us to measure the discrimination threshold of the mean orientation. The object size and spatial frequency were fixed for all patches regardless of depth. However, the physical angular size and absolute spatial frequency covaried with the depth. The results revealed the threshold elevation with depth expansion, especially when the patches formed two clusters at near and far distances, leading to large variations in their retinotopic representations. This finding indicates a minor contribution of similarity of the distal stimuli. Subsequent experiments demonstrated that the variability in physical angular size of the patches significantly influenced the threshold elevation in contrast to that of binocular disparity and absolute spatial frequency. These findings highlight the critical role of physical angular size variability in perceiving mean orientations within the 3-D space.

Optical coherence tomography parameters as prognostic factors for stereopsis after vitrectomy for unilateral epiretinal membrane: a cohort study.

This retrospective cohort study explored the relationship between monocular and interocular optical coherence tomography (OCT) parameters and stereopsis in 56 patients undergoing pars plana vitrectomy (PPV) for unilateral idiopathic epiretinal membrane (IERM). IERM impairs visual functions, with symptoms ranging from asymptomatic to severe impairment. Despite established surgical interventions, including PPV with membrane peeling, the impact on advanced three-dimensional visual functions such as stereopsis remains inadequately investigated. All subjects were assessed for stereopsis, visual acuity, and metamorphopsia, alongside spectral domain OCT parameters. These visual functions significantly improved 3-month postoperatively. Central retinal thickness at the fovea, parafovea, and perifovea (CFT, CRT-3 mm, and CRT-6 mm), ectopic inner foveal layer thickness, and retinal layer thickness notably decreased 1 week to 3 months after surgery. The interocular difference in OCT parameters between bilateral eyes was included as a parameter. Baseline CRT-3 mm difference and inner nuclear layer (INL) thickness were independently correlated with postoperative stereopsis on the Titmus Stereo Test, while baseline CRT-6 mm difference and INL thickness were independently related to stereopsis on the TNO stereotest. This study highlights the substantial enhancement in stereopsis post-IERM surgery, with both interocular and monocular OCT parameters independently influencing postoperative stereopsis. These findings underscore the importance of retinal microstructures in assessing and predicting stereopsis in IERM patients after vitrectomy.

Absolute and relative disparity mechanisms revealed by an equivalent noise analysis.

The precision of stereopsis and vergence are ultimately limited by internal binocular disparity noise. Here we propose an equivalent noise model with both global and local internal disparity noises to provide a unified explanation of both absolute and relative disparity thresholds. To test this model, we developed a psychophysical procedure to measure the equivalent internal disparity noise by adding external disparity noise to random-Gabor-patch stereograms. We used the method of constant stimuli to measure the minimum and maximum disparity thresholds (Dmin and Dmax) for both absolute and relative disparity. Consistent with previous studies, we found that Dmin thresholds are substantially worse for absolute disparity than for relative disparity. We tested three relative disparity mechanisms: (1) the difference between the monocular separations of targets projecting to the two eyes; (2) the direct measurement of relative disparity; and (3) the difference of absolute disparities of targets. Computing the difference of absolute disparities when detecting relative disparity, Mechanism 3 cancels global noise, resulting in a much lower relative Dmin threshold, and provides a reasonable fit to the experimental data. We also found that the presence of as much as 2400 arcsec of external disparity noise does not appear to affect the Dmax threshold. This observation suggests that Dmax is implicated in a mechanism that disregards the disparity variance of individual items, relying instead on the average disparity across all items, supporting the depth model proposed in our previous study (Ding & Levi, 2021), which posits distinct mechanisms governing Dmin and Dmax thresholds.

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

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 < 0.001. Near:-3.7△±4.1△ vs. -33.7△±8.0△, t=-26.1, P < 0.001). Distant stereopsis (3.0 ± 0.6 vs. 3.9 ± 0.4, t = 4.9, P < 0.05) and near stereopsis (2.3 ± 0.5 vs. 2.6 ± 0.4, t = 3.8, P < 0.05) were both significantly improved compared with that of before surgery. 17% and 22% patients rebuilt normal distant stereopsis and normal near stereopsis, respectively. Preoperative distant stereopsis (r=-0.26, P = 0.004) and near stereopsis (r=-0.23, P = 0.011) was significantly negatively correlated with convergence reserve. Multivariable analysis showed that patients' age (ß = 0.003, p = 0.037), anisometropia (ß = 0.015, p = 0.043), and preoperative distant stereopsis (ß = 0.456, p < 0.001) were significantly associated with postoperative distant stereopsis. Patients' age (ß = 0.005, p = 0.044), anisometropia (ß = 0.127, p = 0.034), angle of deviation (ß=-0.230, p = 0.020), and preoperative near stereopsis (ß = 0.136, p < 0.001) were significantly associated with postoperative near stereopsis. CONCLUSION: IXT patients could get eye position fixed after surgery, about 20% patients benefited from stereopsis improvement. Patient's age, binocular anisometropia, angle of deviation and preoperative stereopsis were independent factors influencing postoperative stereopsis.