Vision (Switzerland)最新文献

Texture regularity, for example, the repeating pattern of a carpet, brickwork, or tree bark, is a ubiquitous feature of the visual world. The perception of regularity has generally been studied using multi-element textures whose regularity is manipulated by the addition of random jitter to the elements' nominal positions. Here, we investigate the selectivity of regularity perception for the luminance contrast polarities of the elements. Our psychophysical tool was simultaneous regularity contrast, or SRC, the phenomenon in which the perceived regularity of a central test texture is shifted away from that of the surrounding regularity. Stimuli were composed of arrays of dark and/or white Gaussian elements. Surround and center test textures consisted of either the same ("congruent") or opposite ("incongruent") polarities. In addition, we tested a "mixed" condition consisting of a random mixture of polarities in both the surround and test. The perceived regularity of the test was measured using a match stimulus with the same polarity dimension as the test. The regularity of the match stimulus was adjusted on each trial using a forced-choice staircase procedure and the point-of-subjective equality between the match and test regularities was estimated from the resulting psychometric functions. SRC was observed in both congruent and incongruent conditions, but with the mixed condition, the perceived regularity of the test was shifted toward rather than away from the surround regularity, an example of assimilation, not contrast. The analysis revealed no significant difference in the magnitude of SRC between the congruent and incongruent conditions, suggesting that SRC could be mediated solely by polarity agnostic mechanisms, although there are other possible explanations for the "null" result. However, trend analysis using a non-linear (sigmoidal-shaped) function indicated a significant difference between the congruent and incongruent conditions, which, together with the mixed polarity results, suggests the presence of at least some polarity selective mechanisms. Previous reports have suggested that regularity perception is encoded by the "peakedness" in the distribution of spatial-frequency-tuned linear filter responses. We modelled SRC quantitatively by incorporating peakedness with spatial-frequency-selective surround inhibition and found that the model gave a good account of the SRC data. Possible reasons for the assimilation effect-with the mixed polarity condition are discussed.

Recent advancements in head-up-displays have increased the number of instances where the visual system may face a different accommodative demand for each eye. A limited number of studies on aniso-accommodation exist, reporting contradictory results. We tested the natural capacity of observers to aniso-accommodate anisometropic stimuli. A dichoptic task allowed us to account for certain confounds, including high-level accommodation control. A 2AFC visual task was used, where participants judged if two overlapping sinusoidal gratings, presented dichoptically, had the same orientation. The gratings' spatial frequency could be 1, 4 or 10 c/deg. The accommodative demand for each eye could be independently set to 2D or 4D. The accommodative response for each eye was recorded using an autorefractometer. Higher spatial frequencies and anisometropy had a negative impact on task accuracy. Contrary to expectations, spatial frequencies had no significant impact on accommodation response. The accommodation response to anisometropic stimuli was equal in the two eyes and leaned toward the lower of two demands. Our results confirm that when presented with asymmetrical accommodation demand, the two eyes tend to keep the same refractive power even in a dichoptic-requiring task. They also contradict the guidance of accommodation by spatial frequency in sinusoidal gratings. The visual task provided an objective measure of subjects' performance, allowing for these conclusions to be drawn.

Background: This research was conducted to study changes in iris microcirculation using optical coherence tomography angiography (OCTA) in patients with primary open-angle glaucoma after selective laser trabeculoplasty (SLT).

Methods: All patients received standard SLT. OCTA examination of the iris was performed before SLT and one day and seven days after SLT using RTVue-XR with a 3 mm scan pattern and follow-up function. Iris vascularity was calculated with ImageJ software (version 1.53k) as vessel density on binarized images. Correlation between absolute or percentage changes in iris vessel density and intraocular pressure (IOP) changes was calculated.

Results: A total of 31 eyes (31 patients, 10 females, 70.7 ± 8.9 years) were included. Iris vessel density increased statistically significantly (p = 0.002) the day after SLT followed by a decrease to baseline level at one week. A statistically significant correlation (r = 0.57, p = 0.002) was found between the percentage change in iris vessel density the day after the procedure and IOP change at three months.

Conclusion: SLT is associated with a transitory increase in iris vessel density, which can be observed with OCTA the day after the procedure. Substantial increase in iris vascularity is associated with a poorer IOP-lowering effect of SLT in eyes with open-angle glaucoma.

Eyes with maculopathy usually have poor fixation stability (FS) and develop a new preferred retinal locus (PRL). The exact FS and PRL have never been studied in diabetic macular ischemia (DMI). In this one-year observational study, we recruited 79 patients (145 eyes) with evidence of DMI on optical coherence tomography angiography (OCTA). Microperimetry (MP) was performed at baseline and 52 weeks. Overall, DMI eyes demonstrated relatively stable FS without evolving into eccentric fixation over one year. When comparing the better-seeing eye (BSE) with the worse-seeing eye (WSE) in eyes with bilateral DMI, the latter presented with a larger bivariate contour ellipse area (BCEA) initially but gradually aligned with the one in the BSE at the end of the study. Conversely, the foveolar retinal sensitivity (RS) worsened significantly alongside the extension of disorganization of the retinal inner layers (DRIL) in the WSE at one year despite the best-corrected visual acuity (BCVA) being maintained. This suggests that foveolar RS might reflect the start of DMI deterioration more sensitively than BCVA.

Paracentral acute middle maculopathy (PAMM) is a macular condition primarily detected using optical coherence tomography (OCT) imaging. It presents as hyperreflective bands within the inner nuclear layer (INL) of the retina, often leading to localized degenerative phenomena. PAMM is a condition that reveals a dysfunction in the microvascular network of the retina. However, it is not an isolated phenomenon but rather an indicator of deeper and even systemic, prevalently vascular-related issues related to a wide array of conditions that impact circulation, including retinal vein and artery occlusion, diabetic retinopathy, and hypertensive retinal vascular changes. PAMM occurs due to impaired perfusion within the retinal deep capillary plexus, clinically leading to subtle but noticeable blind spots (scotomas) in the central visual field. Recent advances in imaging technology, particularly optical coherence tomography angiography (OCTA), have provided a clearer view of the underlying vascular alterations. Thus, PAMM may currently serve as a biomarker in broader ocular and systemic pathologies before disease progression. This review explores the latest reports in the literature on PAMM, from its characteristic imaging features to the evolving theories behind its development. By bridging the gap between ophthalmology and systemic health, PAMM may facilitate earlier diagnosis and tailored management strategies for conditions that extend far beyond the eye. Understanding this entity could ultimately transform our approach to assessing vascular health toward further research, risk prediction, and patient care.

The impact of ambient brightness surroundings on the peak velocities of visually guided saccades remains a topic of debate in the field of eye-tracking research. While some studies suggest that saccades in darkness are slower than in light, others question this finding, citing inconsistencies influenced by factors such as pupil deformation during saccades, gaze position, or the measurement technique itself. To investigate these, we developed RELAY (Robotic EyeLink AnalYsis), a low-cost, stepper motor-driven artificial eye capable of simulating human saccades with controlled pupil, gaze directions, and brightness. Using the EyeLink 1000, a widely employed eye tracker, we assessed accuracy and precision across three illumination settings. Our results confirm the reliability of the EyeLink 1000, demonstrating no artifacts in pupil-based eye tracking related to brightness variations. This suggests that previously observed changes in peak velocities with varying brightness are likely due to human factors, warranting further investigation. However, we observed systematic deviations in measured pupil size depending on gaze direction. These findings emphasize the importance of reporting illumination conditions and gaze parameters in eye-tracking experiments to ensure data consistency and comparability. Our novel artificial eye provides a robust and reproducible platform for evaluating eye tracking systems and deepening our understanding of the human visual system.

This study compared the refraction measurements of the ClickCheck™ device (CCD), Topcon KR-8000, and subjective clinical refractometry (SCR) in Brazilian public school students with limited access to eye care. Eighty-seven eyes of healthy students aged 7 to 17 underwent refractometry using the CCD, Topcon KR-8000, and SCR methods under cycloplegia, with only the right-eye data analyzed. For comparison, the measurements were converted into spherical equivalents (SEs) and vector magnitudes. The mean SE difference between CCD and Topcon KR-8000 was -0.27 ± 0.58 (p < 0.0001), while the vector magnitudes at the 90° and 135° meridians were -0.23 ± 0.55 (p = 0.0001) and +0.04 ± 0.47 (p = 0.2246), respectively, demonstrating no clinical relevance. Similarly, the mean SE difference between CCD and SCR was -0.18 ± 0.58 (p = 0.065), with vector magnitudes of -0.20 ± 0.50 (p = 0.0003) at 90° and +0.03 ± 0.46 (p = 0.3730) at 135°, also lacking clinical relevance. Despite statistically significant differences between the methods, the findings confirm strong agreement, validating CCD as an effective refractive assessment tool for children in low-resource settings. These methods can enhance access to refraction services in underserved populations.

Age-related macular degeneration (AMD) is a multifactorial disorder influenced by genetic, lifestyle, nutritional, and systemic health factors that contribute to increased oxidative stress and chronic inflammation in the retina. This article reviews the recent literature on modifiable lifestyle risk factors for the development and progression of AMD. Smoking (current and former), physical inactivity, prolonged sunlight exposure, as well as conditions such as diabetes, hypertension, cardiovascular disease, and obesity have all been associated with an increased risk of early AMD and its progression. The Age-Related Eye Disease Studies (AREDS and AREDS2) have shown that a specific combination of vitamins E and C, zinc, copper, lutein, and zeaxanthin can significantly reduce the risk of AMD progressing from dry to wet form. Additionally, adherence to a Mediterranean diet, rich in vegetables, fruits, legumes, whole grains, and nuts, has been linked to a lower risk of both early and late AMD. Emerging evidence suggests that these benefits may be influenced by the gut microbiota, as well as genetic and epigenetic factors. Further research into the interactions between these risk factors could pave the way for targeted therapies aimed at preventing or slowing AMD progression.

(1) Background: Perceptual constancies are found in numerous categories of visual perception; color, lightness, and size constancy are notable examples where the perception of a visual scene remains constant, even with changing optical conditions. Constancies such as these are essential for survival, as they reduce the unpredictability of the world. In this study, we tested the resiliency of motion perception under widely differing spectral conditions. (2) Methods: Sixty healthy subjects (age range 18 to 26) were tested. Motion perception performance and thresholds were assessed using a novel, ecologically valid, psychophysical task implementing modern instruments. A broadband xenon bulb was used as a light source to emulate the spectral characteristics of natural daylight; 3 filter conditions were included to emulate different conditions of environmental light (short-wave, 400 nm-500 nm; medium-wave, 500 nm-600 nm; and long-wave, 600 nm-700 nm). (3) Results: In general, our findings showed that varying the spectral content of the broadband source did not change motion perception performance or thresholds for subjects. (4) Conclusions: These findings indicate that motion perception is highly resistant to changes in optical conditions, such as dramatically different spectral illuminants. This evidence is consistent with motion being considered among the perceptual constancies.

Chronic low back pain (LBP) impairs balance control due to deficits in sensory integration, yet limited research examines postural sway under varying visual conditions. This study assessed the effects of visual input on postural stability using the normalized stability index, sway excursions, and contralateral toe-touch durations during repeated one-leg standing tasks. Thirty-two adults with LBP and 40 control subjects performed dominant limb standing on a force plate. Outcome measures included the Oswestry disability index, visual analog scale, normalized stability index, sway excursions (anteroposterior [AP], mediolateral [ML]), and contralateral toe-touch duration. The LBP group showed a significant interaction for the normalized stability index under visual conditions (F = 4.95, p = 0.03) with reduced stability in the second trial of the eyes-open condition (t = 1.71, p = 0.04). Sway excursions increased in the AP direction during the first trial (t = -2.43, p = 0.01) and in the ML (t = -2.09, p = 0.02) and AP (t = -1.84, p = 0.03) directions during the third trial. Contralateral toe-touch duration increased in the second trial (t = -2.06, p = 0.02). Individuals with LBP exhibited balance deficits, particularly under eyes-open conditions, relying on compensatory strategies. Optimizing neuromuscular control and sensory integration may improve postural stability.