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When two sine waves that differ slightly in orientation are presented to the two eyes separately, a single cyclopean sine wave is perceived. However, it is unclear how the brain calculates its orientation. Here, we used a signal detection rating method to estimate the perceived orientation when the two eyes were presented with Gabor patches that differed in both orientation and contrast. We found a nearly linear combination of orientation when both targets had the same contrast. However, the binocular percept shifted away from the linear prediction towards the orientation with the higher contrast, depending on both the base contrast and the contrast ratio. We found that stimuli that differ slightly in orientation are combined into a single percept, similarly for monocular and binocular presentation, with a bias that depends on the interocular contrast ratio. Our results are well fitted by gain-control models, and are consistent with a previous study that favoured the DSKL model that successfully predicts binocular phase and contrast combination and binocular contrast discrimination. In this model, the departures from linearity may be explained on the basis of mutual suppression and mutual enhancement, both of which are stronger under dichoptic than monocular conditions.

Purpose: To compare the effectiveness and safety of a novel binocular eye-tracking-based-home-treatment (CureSight) to patching for the treatment of amblyopia., Design: Prospective, masked, multicenter randomized controlled trial., Methods: One hundred forty-nine children 4 to < 9 years with anisometropic, small-angle strabismic, or mixed-mechanism amblyopia were randomized to either binocular dichoptic treatment (n=75) or patching (n=74). The binocular dichoptic treatment group used the CureSight system for 90 min/day, 5 days/week for 16 weeks (120 hours). The patching group received 2-hour patching 7 days/week (224 hours). The primary outcome was the mean improvement from baseline in amblyopic eye visual acuity (VA) to week 16 in both study groups (non-inferiority of ≤0.10 logarithm of the minimum angle of resolution [logMAR])., Results: In the modified intent-to-treat (mITT) group, the mean improvement from baseline at week 16 in the binocular treatment group was noninferior to patching group improvement (0.034 logMAR [95% CI -0.009 to 0.076]). In the per-protocol (PP) dataset, the mean improvement from baseline at week 16 in the binocular treatment group was superior to patching group improvement (0.05 logMAR ([95% CI; 0.007 to 0.097]). There was no significant between-group difference in the magnitude of improvement in stereoacuity in the mITT and the PP datasets. Median adherence in the mITT binocular treatment group (94.0%) was also significantly higher than in the patching group (83.9%; p=0.0038)., Conclusions: A binocular, eye-tracking-based amblyopia home treatment is noninferior to, and produced better visual outcomes than, patching in children with anisometropic, small angle strabismus and mixed mechanism amblyopia., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: To report the long-term outcomes of a noninferiority randomized controlled trial (RCT) with a binocular eye-tracking-based home treatment (CureSight; NovaSight, Ltd.) in patients with amblyopia., Design: Prospective, multicenter, nonrandomized, long-term follow-up observational study of an RCT., Methods: Forty-three children 4 to <9 years of age with anisometropic, small-angle strabismic, or mixed-mechanism amblyopia were initially treated for 16 weeks (NCT05185076) with CureSight. In this planned observational follow-up study, 38 patients with no additional amblyopia treatment were evaluated at 12 weeks post-treatment, and 27 were evaluated at 1-year post-treatment. The main outcome measures were visual acuity (VA), stereoacuity, and amblyopia recurrence at 12- and 52-week post-treatment., Results: At 12-week post-treatment, improvement in amblyopic eye VA was maintained vs baseline (0.27 ± 0.14 logMAR, P< .0001), with no change vs the end-of-treatment visit (P > .05). At 1 year there was a partial reduction in the amblyopic eye VA gain of 0.085±0.1 logMAR compared to end-of-treatment (P = .001), but the residual gain of 0.20±0.14 logMAR compared to baseline was statistically significant (P < .0001). Gains in stereoacuity and binocular VA were maintained vs baseline at both 12-weeks and 1-year post-treatment (P < .0001), with no change vs end-of-treatment (P > .05). Amblyopia recurrence (a worsening of ≥2 logMAR levels compared with end-of-treatment) occurred in 2/38 patients at 12-weeks post-treatment (5.3%), and in 5/27 patients at 1-year post-treatment (20.4%)., Conclusions: VA and stereopsis gains following binocular treatment with CureSight were maintained at 1 year without additional treatment., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: To assess visual acuity (VA) and stereoacuity (SA) improvements in children with amblyopia treated with either binocular dichoptic treatment or patching treatment., Methods: In this pilot prospective coherent study, 34 participants between 4 and 9 years of age with unilateral anisometropic amblyopia and without history of prior amblyopia treatment were enrolled into three groups. Full treatment group (FTG; n  = 12): participants were prescribed the binocular dichoptic treatment to watch for 90 minutes per day, 5 days a week. Part-time treatment group (PTTG; n  = 8): participants were prescribed the same binocular treatment as FTG, 90 minutes per day, 3 days per week. Patching treatment group (PTG; n  = 14): participants wore an adhesive patch over the dominant eye for 2 hours per day, 7 days per week. Amblyopic-eye distance visual acuity (DVA), near visual acuity (NVA) and SA were evaluated at baseline, 4, 8, and 12 weeks., Results: At 12 weeks, mean amblyopic-eye DVA improved 1.8 lines (95% CI, 1.1-2.5) in FTG, 1.5 lines (95% CI, 0.4-2.7) in PTTG and 3.0 lines (95% CI, 2.0-4.0) in PTG. The amblyopic-eye NVA improved 2.9 lines (95% CI, 2.4-3.5) in FTG, 1.7 lines (95% CI, 0.5-3.0) in PTTG and 2.8 lines (95% CI, 1.8-3.9) in PTG. The SA improved 0.38 log-arcseconds (95% CI, 0.24-0.53) in FTG, 0.59 log-arcseconds (95% CI, 0.36-0.82) in PTTG and 0.40 log-arcseconds (95% CI, 0.13-0.67) in PTG. No significant differences were found in DVA, NVA or SA improvement between FTG and PTG at 12 weeks., Conclusions: VA and SA after binocular dichoptic treatment produced a similar therapeutic outcome to patching, suggesting a potential value for binocular therapy when treating anisometropic moderate degree of Children's amblyopia.

Purpose: Comparing visual outcomes after use of a novel binocular eye-tracking-based home treatment (CureSight; NovaSight, Ltd) with patching., Design: Prospective, multicenter, randomized, masked, controlled, noninferiority pivotal trial., Participants: One hundred three children 4 to < 9 years with anisometropic, small-angle strabismic or mixed-mechanism amblyopia were randomized 1:1 to either CureSight treatment or patching., Methods: The CureSight treatment uses combined anaglyph glasses and an eye tracker to induce real-time blur around the fellow eye fovea in dichoptic streamed video content. Participants used the device for 90 minutes/day, 5 days/week for 16 weeks (120 hours). The patching group received 2 hours of patching 7 days/week (224 hours). The prespecified noninferiority margin was 1 line., Main Outcome Measures: The primary outcome was the improvement in the amblyopic eye visual acuity (VA), modeled with a repeated measures analysis of covariance. Secondary outcomes included stereoacuity, binocular VA, and treatment adherence rates, analyzed by a 1-sample Wilcoxon test within each group and a 2-sample Wilcoxon test comparing groups. Safety outcomes included the frequency and severity of study-related adverse events (AEs)., Results: CureSight group VA improvement was found to be noninferior to patching group improvement (0.28 ± 0.13 logarithm of the minimum angle of resolution [logMAR] [P < 0.0001] and 0.23 ± 0.14 logMAR [P < 0.0001], respectively; 90% confidence interval [CI] of difference, -0.008 to 0.076). Stereoacuity improvement of 0.40 log arcseconds (P < 0.0001) and improved binocular VA (0.13 logMAR; P < 0.0001) were observed in the binocular treatment group, with similar improvements in the patching group in stereoacuity (0.40 log arcseconds; P < 0.0001) and binocular VA (0.09 logMAR; P < 0.0001), with no significant difference between improvements in the 2 groups in either stereoacuity (difference, 0; 95% CI, -0.27 to -0.27; P = 0.76) or binocular VA (difference, 0.041; 95% CI, -0.002 to 0.085; P = 0.07). The binocular treatment group had a significantly higher adherence than the patching group (91% vs. 83%; 95% CI, -4.0% to 21%; P = 0.011). No serious AEs were found., Conclusions: Binocular treatment was well tolerated and noninferior to patching in amblyopic children 4 to < 9 years of age. High adherence may provide an alternative treatment option for amblyopia., Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references., (Copyright © 2022 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Objectives: To assess the effectiveness of an eye-tracking-based test (ETBT) to measure eye deviation angle vs. a manual prism alternating cover test (PACT) in children with strabismus., Design: The prospective, masked, cross-sectional study included 95 children aged 1.8 years and older. Eye deviation was tested twice by each of ETBT and PACT. Each subject underwent four strabismus measurements, two by the ETBT and two by PACT. In each test, subjects were fixated on accommodative targets at 50 cm, with habitual optical correction allowed. Masked examiners compared the manual PACT results with those of the ETBT., Results: There was a high correlation (about 90%) between the ETBT and PACT. Repeatability of ETBT was higher than that of PACT (correlation coefficients of 0.99 and 0.91 respectively, p < .002). Age, strabismus type, and eye deviation measurement did not affect repeatability of ETBT. However, in PACT, results could not be correlated between the two examiners when the deviation was larger than 40 prism diopters., Conclusions: The ETBT was effective in measuring eye deviation in children as young as 1.8 years. The ETBT showed higher repeatability compared to PACT.

Purpose: Manual measurements of strabismus are subjective, time consuming, difficult to perform in babies, toddlers, and young children, and rely on the examiner's skill and experience. An automated system, based on eye tracking and dedicated full occlusion glasses, was developed to provide a fast, objective, and easy-to-use alternative to the manual measurements of strabismus. This study tested the efficacy of the system in determining the presence of strabismus in children, as well as its type and the amount of deviation, in addition to differentiating between phorias and tropias., Design: A prospective, masked, inter-rater reliability study., Methods: A prospective, masked, cross-sectional study included 69 children, 3-15 years of age. A cover-uncover test and a prism alternating cover test (PACT) for the primary gaze, at a distance of 50 cm, were performed by 2 independent, masked examiners and by the automated system., Results: A high correlation was found between the automated and the manual test results (R = 0.9 and P < 0.001 for the horizontal deviation, and R = 0.91 and P < 0.001 for the vertical deviations, with 100% correct identification of the type of deviation). The average automated test duration was 46 seconds. The Bland-Altman plot, used to compare the 2 measurement methods, showed a mean value of -2.9 prism diopters (PD) and a half-width of the 95% limit of agreement of ±11.4 PD., Conclusion: The automated system provides precise detection and measurements of ocular misalignment and differentiated between phorias and tropias. It can be used in participants from the ages of 3 years old and up., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

Color deficiency is a common inherited disorder affecting 8% of Caucasian males with anomalous trichromacy (AT); it is the most common type of inherited color vision deficiency. Anomalous trichromacy is caused by alteration of one of the three cone-opsins' spectral sensitivity; it is usually considered to impose marked limitations for daily life as well as for choice of occupation. Nevertheless, we show here that anomalous trichromat subjects have superior basic visual functions such as visual acuity (VA), contrast sensitivity (CS), and stereo acuity, compared with participants with normal color vision. Both contrast sensitivity and stereo acuity performance were correlated with the severity of color deficiency. We further show that subjects with anomalous trichromacy exhibit a better ability to detect objects camouflaged in natural gray scale figures. The advantages of color-deficient subjects in spatial vision performance could explain the relatively high prevalence of color-vision polymorphism in humans., Competing Interests: The authors have declared that no competing interests exist.

Israeli Air Force (IAF) pilots continue flying combat missions after the symptoms of natural near-vision deterioration, termed presbyopia, begin to be noticeable. Because modern pilots rely on the displays of the aircraft control and performance instruments, near visual acuity (VA) is essential in the cockpit. We aimed to apply a method previously shown to improve visual performance of presbyopes, and test whether presbyopic IAF pilots can overcome the limitation imposed by presbyopia. Participants were selected by the IAF aeromedical unit as having at least initial presbyopia and trained using a structured personalized perceptual learning method (GlassesOff application), based on detecting briefly presented low-contrast Gabor stimuli, under the conditions of spatial and temporal constraints, from a distance of 40 cm. Our results show that despite their initial visual advantage over age-matched peers, training resulted in robust improvements in various basic visual functions, including static and temporal VA, stereoacuity, spatial crowding, contrast sensitivity and contrast discrimination. Moreover, improvements generalized to higher-level tasks, such as sentence reading and aerial photography interpretation (specifically designed to reflect IAF pilots' expertise in analyzing noisy low-contrast input). In concert with earlier suggestions, gains in visual processing speed are plausible to account, at least partially, for the observed training-induced improvements., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Collinear facilitation of contrast sensitivity supported by lateral interactions within primary visual cortex is implicated in contour and object perception, with neural correlates in several frequency bands. Although higher component of the ERP power spectrum, the gamma-band, is postulated to reflect object representation, attention and memory, its neuronal source has been questioned, suggesting it is an artifact reflecting saccadic eye movements. Here we explored the gamma-band activity during collinear facilitation with no saccade-related confounds. We used single-trial spectral analysis of ERP in occipital channels in a time-window of nearly complete saccadic suppression and discarded sporadic trials containing saccades, in order to avoid saccadic artifacts. Although converging evidence suggests that gamma-band oscillations emerge from local excitatory-inhibitory balance involving GABAergic inhibition, here we show activity amplification during facilitatory collinear interactions, presumably dominated by excitations, in the gamma-band 150-350 milliseconds following onset of low near-threshold contrast stimulus. This result highlights the potential role of gamma-band oscillations in neuronal encoding of basic processes in visual perception. Thus, our findings suggest that gamma-band ERP spectrum analysis may serve as a useful and reliable tool for exploring basic perception, both in normal adults and in special populations.

The goal of the present study was to evaluate the dependence of perceptual learning gains on initial visual acuity (VA), in a large sample of subjects with a wide range of VAs. A large sample of normally sighted and presbyopic subjects (N = 119; aged 40 to 63) with a wide range of uncorrected near visual acuities (VA, -0.12 to 0.8 LogMAR), underwent perceptual learning. Training consisted of detecting briefly presented Gabor stimuli under spatial and temporal masking conditions. Consistent with previous findings, perceptual learning induced a significant improvement in near VA and reading speed under conditions of limited exposure duration. Our results show that the improvements in VA and reading speed observed following perceptual learning are closely linked to the initial VA, with only a minor fraction of the observed improvement that may be attributed to the additional sessions performed by those with the worse VA.

Seeing with two eyes usually helps one respond faster. Here we show that with ambiguous stimuli, binocular viewing can paradoxically slow down reaction time. This is explained by the observers basing their decision on a noisy neuronal representation within the visual system, with the added noise breaking the symmetry between the two possible interpretations. Binocular integration improves the representation by reducing the noise, increasing ambiguity, and decision time. The neuronal Accumulator (Race) model is applied to quantify the underlying binocular integration. The model accounts for the distributions of reaction times, and predicts suboptimal integration between eyes. We conclude that under ambiguous stimulation neuronal noise within the visual system determines responses.

Spatial crowding decreases object recognition and conscious visual perception in clutter. In a previous study we used brief presentation times to reveal the effects of a crowded presentation in the fovea. Here we aimed to test the relationships between varying visual acuity (VA) and crowding in the fovea, under the assumption that in uncorrected presbyopia, the processing is relatively normal, whereas the retinal input is blurred. We tested whether normal participants whose near VA is gradually reduced due to age-related deterioration (presbyopia, or "aging eye") will show an acuity-dependent increase in foveal crowding. We used brief presentations and acuity-threshold letter targets in order to magnify the crowding-effect amplitude in the fovea. A total of 195 participants with an age range of 20-68 years and an average of 44.3 ± 11.7 years (M ± SD) were divided into four age groups, all without any optical correction for the near distance. Our findings show that crowding is proportional to VA. This proportionality is affected by VA-age dependency, with a nonlinear S-shaped pattern: A steep VA reduction begins to develop, which is compatible with the normal onset age of presbyopia symptoms and a saturation in the VA-age dependency in the oldest age group, for which we propose a VA-eccentricity account. Finally, there is a high variance in the crowding amplitude in the young, even before the onset age of presbyopia symptoms, suggesting crowding conditions with limited presentation times as a highly sensitive measure of VA, which predicts visual performance in complex tasks, such as reading.

Spatial crowding impairs conscious visual perception and object recognition in clutter.Short presentation times produce crowding in the normal fovea, in young participants and in uncorrected presbyopes ("aging eye"), measured as reduced visual acuity (VA). On the other hand, perceptual learning improves near VA in healthy young adults, in presbyopia, and in amblyopia. Here we aimed at exploring the effects of perceptual training on crowded VA in uncorrected presbyopes with naturally decreased VA, with two specific objectives: (a) to objectively measure crowded VA, taking advantage of the natural deterioration of near visual acuity from being normal or better than normal (i.e., 20/20 or better) in young participants to naturally decreasing in uncorrected presbyopes; and (b) to explore whether perceptual training previously shown to improve visual functions as complex as reading will affect crowded VA. Visual acuity was measured under crowded and uncrowded conditions by having subjects identify letters presented for short durations ranging from 34 to 116 msec. Training consisted of detecting brief Gabor stimuli under spatial and temporal masking conditions, using the GlassesOff mobile application (GlassesOff, Inc., New York, NY)on iOS devices from a distance of 40 cm. Before training, a robust reduction in crowded VA was found in the fovea of presbyopes. Training resulted in significant improvement of letter identification under both crowded and uncrowded VA conditions for all stimulus durations. After training, the crowded condition threshold reached the level of the uncrowded threshold measured before training. Thus, training enabled the subjects to overcome the effect of reduced VA under the crowded condition. We suggest that more efficient spatial and temporal processing induced by perceptual learning allows one to improve crowded VA, including that found on naturally reduced near VA, and that this effect may transfer to improve complex visual functions, such as reading and object recognition.

Long-term deprivation of normal visual inputs can cause perceptual impairments at various levels of visual function, from basic visual acuity deficits, through mid-level deficits such as contour integration and motion coherence, to high-level face and object agnosia. Yet it is unclear whether training during adulthood, at a post-developmental stage of the adult visual system, can overcome such developmental impairments. Here, we visually trained LG, a developmental object and face agnosic individual. Prior to training, at the age of 20, LG's basic and mid-level visual functions such as visual acuity, crowding effects, and contour integration were underdeveloped relative to normal adult vision, corresponding to or poorer than those of 5-6 year olds (Gilaie-Dotan, Perry, Bonneh, Malach & Bentin, 2009). Intensive visual training, based on lateral interactions, was applied for a period of 9 months. LG's directly trained but also untrained visual functions such as visual acuity, crowding, binocular stereopsis and also mid-level contour integration improved significantly and reached near-age-level performance, with long-term (over 4 years) persistence. Moreover, mid-level functions that were tested post-training were found to be normal in LG. Some possible subtle improvement was observed in LG's higher-order visual functions such as object recognition and part integration, while LG's face perception skills have not improved thus far. These results suggest that corrective training at a post-developmental stage, even in the adult visual system, can prove effective, and its enduring effects are the basis for a revival of a developmental cascade that can lead to reduced perceptual impairments., (© 2014 The Authors. Developmental Science Published by John Wiley & Sons Ltd.)

Visual crowding, as context modulation, reduce the ability to recognize objects in clutter, sets a fundamental limit on visual perception and object recognition. It's considered that crowding does not exist in the fovea and extensive efforts explored crowding in the periphery revealed various models that consider several aspects of spatial processing. Studies showed that spatial and temporal crowding are correlated, suggesting a tradeoff between spatial and temporal processing of crowding. We hypothesized that limiting stimulus availability should decrease object recognition in clutter. Here we show, for the first time, that robust contour interactions exist in the fovea for much larger target-flanker spacing than reported previously: participants overcome crowded conditions for long presentations times but exhibit contour interaction effects for short presentation times. Thus, by enabling enough processing time in the fovea, contour interactions can be overcome, enabling object recognition. Our results suggest that contemporary models of context modulation should include both time and spatial processing.

Our recent neurophysiological findings provided evidence for collinear facilitation in detecting low-contrast Gabor patches (GPs) and for the abolishment of these collinear interactions by backward masking (BM) (Sterkin et al., 2008; Sterkin, Yehezkel, Bonneh, et al., 2009). We suggested that the suppression induced by the BM eliminates the collinear facilitation. Moreover, our recent study showed that training on a BM task overcomes the BM effect, hence, improves the processing speed (Polat, 2009). Here we applied training on detecting a target that is followed by BM in order to study whether reinforced facilitatory interactions can overcome the suppressive effects induced by BM. Event-Related Potentials (ERPs) were recorded before and after ten training sessions performed on different days. Low-contrast, foveal target GP was simultaneously flanked by two collinear high-contrast GPs. In the BM task, another identical mask was presented at different time-intervals (ISIs). Before training, BM induced suppression of target detection, at the ISI of 50 ms, in agreement with earlier behavioral findings. This ISI coincides with the active time-window of lateral interactions. After training, our results show a remarkable improvement in all behavioral measurements, including percent of correct responses, sensitivity (d'), reaction time (RT) and the decision criterion for this ISI. The ERP results show that before training,BM attenuated the physiological markers of facilitation at the same ISI of 50 ms, measured as the amplitude of the negative N1 peak (latency of 260 ms). After the training, the sensory representation, reflected by P1 peak, has not changed, consistent with the unchanged physical parameters of the stimulus. Instead, the shorter latency (by 20 ms, latency of 240 ms) and the increased amplitude of N1 represent the development of faster and stronger facilitatory lateral interactions between the target and the collinear flankers. Thus, previously effective backward masking became ineffective in disrupting the collinear facilitation. Moreover, a high-amplitude late peak (P4, latency of 610-630 ms) was not affected by training, however its high correlation with RT (95%) before training was significantly decreased (to 76%), consistent with a lower-level representation of a trained skill. We suggest that perceptual learning that strengthens collinear facilitation results in a faster processing speed., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Presbyopia, from the Greek for aging eye, is, like death and taxes, inevitable. Presbyopia causes near vision to degrade with age, affecting virtually everyone over the age of 50. Presbyopia has multiple negative effects on the quality of vision and the quality of life, due to limitations on daily activities - in particular, reading. In addition presbyopia results in reduced near visual acuity, reduced contrast sensitivity, and slower processing speed. Currently available solutions, such as optical corrections, are not ideal for all daily activities. Here we show that perceptual learning (repeated practice on a demanding visual task) results in improved visual performance in presbyopes, enabling them to overcome and/or delay some of the disabilities imposed by the aging eye. This improvement was achieved without changing the optical characteristics of the eye. The results suggest that the aging brain retains enough plasticity to overcome the natural biological deterioration with age.

The emmetropization process involves fine-tuning the refractive state by altering the refractive components toward zero refraction. In this study, we provided light-dark cycle conditions at several intensities and examined the effect of light intensity on the progression of chicks' emmetropization. Chicks under high-, medium-, and low-light intensities (10,000, 500, and 50 lux, respectively) were followed for 90 days by retinoscopy, keratometry, as well as ultrasound measurements. Emmetropization was reached from days 30-50 and from days 50-60 for the low- and medium-intensity groups, respectively. On day 90, most chicks in the low-intensity group were myopic, with a mean refraction of -2.41D (95% confidence interval (CI) -2.9 to -1.8D), whereas no chicks in the high-intensity group developed myopia, but they exhibited a stable mean hyperopia of +1.1D. The medium-intensity group had a mean refraction of +0.03D. The low-intensity group had a deeper vitreous chamber depth and a longer axial length compared with the high-intensity group, and shifted refraction to the myopic side. The low-intensity group had a flatter corneal curvature, a deeper anterior chamber, and a thinner lens compared with the high-intensity group, and shifted refraction to the hyperopic side. In all groups the corneal power was correlated with the three examined levels of log light intensity for all examined times (e.g., day 20 r = 0.6 P < 0.0001, day 90 r = 0.56 P < 0.0001). Thus, under light-dark cycles, light intensity is an environmental factor that modulates the process of emmetropization, and the low intensity of ambient light is a risk factor for developing myopia., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Passive ophthalmic optic devices correct refractive defects of the eye but are not designed to employ neural adaptation processes. An extended depth of focus technology is implemented on conventional refractive devices, such as spectacles and contact lenses, and its testing is described. This technology is capable of simultaneously correcting all refractive errors, such as myopia, hyperopia, presbyopia, regular/irregular astigmatism, as well as their combinations. This is achieved by exploiting the capacity of the visual system for adaptation to contrast as well as its capability of creating a coherent continuous visual field out of discrete lines of sight.

The visual system can adapt to optical blur, whereby the adapted image is perceived as sharp. Here we show that adaptation reduces blur-induced biases in shape perception, with repeated adaptations (perceptual learning), leading to unbiased perception upon re-exposure to blur. Observers wore a cylindrical lens of +1.00 D on one eye, thus simulating monocular astigmatism. The other eye was either masked with a translucent blurred lens (monocular) or unmasked (dichoptic). Adaptation was tested in several repeated sessions with a proximity-grouping task, using horizontally or vertically arranged dot-arrays, without feedback, before, after, and throughout the adaptation period. A robust bias in global-orientation judgment was observed with the lens, in accordance with the blur axes. After the observer wore the lens for 2 h, there was no significant change in the bias, but after 4 h, the monocular condition, but not the dichoptic, resulted in reduced bias. The adaptation effect of the monocular 4-h adaptation was preserved, and even improved, when the lens was re-applied the next day, indicating learning. After-effects were observed under all experimental conditions except for the 4-h monocular condition, where learning took place. We suggest that, with long experience, adaptation is transferred to a long-term memory that can be instantly engaged when blur is re-applied, or disengaged when blur is removed, thus leaving no after-effects. The comparison between the monocular and dichoptic conditions indicates a binocular cortical site of plasticity., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Purpose: To measure the optical performance of an extended depth of focus (EDOF) intraocular lens (IOL), which provides an imaging solution for near, intermediate, and distance ranges, and to compare its optical performance to available bifocal IOLs with various extents of decentration and astigmatism aberrations., Methods: A special profile that performs interference principle-based focal extension is engraved on the top of a monofocal rigid IOL. An optical bench based on the L&B eye model was used to test the performance in comparison with the bifocal AcrySof ReSTOR SA60D3 lens (Alcon Laboratories Inc)., Results: The imaging performances at near, intermediate, and distance ranges were mapped. Different decentration parameters and amount of astigmatism aberration were tested. In numerical simulations and the experimental bench, the EDOF IOL was demonstrated to have good visual acuity in near, intermediate, and distance ranges as well as reduced sensitivity to decentration of up to 0.75 mm and the capability of correcting astigmatism aberrations of up to 1.00 diopter., Conclusions: Extended depth of focus technology is capable of providing clear and focused vision at near, intermediate, and distance ranges. Its high quality imaging is obtained under large decentration conditions and residual astigmatism. This capability broadens the potential use of the technology beyond its application as a simultaneous multifocal lens., (Copyright 2010, SLACK Incorporated.)

The purpose of this Letter is to design, develop, fabricate, and test in clinical trials a new (to our knowledge) type of contact lenses that provides simultaneous near and distance focused vision for presbyopic subjects, including those with up to 2.00 diopters (D) of regular/irregular astigmatism, as an alternative to multifocal contact lenses. The purpose is obtained by generating an optical pattern on the front surface of contact lenses, capable of extending the depth of focus of lenses by 3.00 D with high visual contrast. The pattern was fabricated on top of contact lenses and tested by the use of an eye simulation as well as in clinical trials. Use of the extended depth of focus contact lens enabled patients to achieve good visual acuity and contrast sensitivity for both distance and near vision without compromising the energy distribution or the visual fields.

Continuous exposure of chicks to light was shown to result in severe hyperopia, accompanied by anterior segment changes, such as severe corneal flattening. Since rearing chicks in complete darkness results only in mild hyperopia and minor changes in corneal curvature, we hypothesized that light intensity may play a role in the development of refractive changes under continuous light illumination. To test this hypothesis, we examined the effects of rearing chicks under various continuous light intensities. More specifically, we investigated the refractive parameters of the chicks' eyes, and avoided light cycling effects on ocular development. To this end, thirty-eight chicks were reared under 24-h incandescent illumination, at three different light intensities: 10,000 lux (n=13), 500 lux (n=12), and 50 lux (n=13). Their eyes underwent repeated retinoscopy, keratometry, and ultrasound biometry, as well as caliper measurements of enucleated eyes. Both refraction and corneal refractive power were found to be correlated with light intensity. On day 90 after hatching, exposure to light intensities of 10,000, 500, and 50 lux resulted in hyperopia of +11.97+/-3.7 (mean+/-SD) +7.9+/-4.08 and +0.63+/-3.61 diopters (D), respectively. Under those intensities, corneal refractive power was 46.10+/-3.62, 49.72+/-4.16, and 56.88+/-4.92D, respectively. Axial length did not differ significantly among the groups. The vitreous chamber was significantly deeper in the high than in the low-intensity groups. Thus, during the early life of chicks exposed to continuous lighting, light intensity affects the vitreous chamber depth as well as the anterior segment parameters, most notably the cornea. The higher the intensity, the more severe was the corneal flattening observed and the hyperopia that developed, whereas continuous illumination at low intensities resulted in emmetropia. Thus, light intensity is an important factor that should be taken into account when studying refractive development.

T emporal masking is a paradigm that is widely used to study visual information processing. When a mask is presented, typically within less than 100 msec before or after the target, the response to the target is reduced. The results of our psychophysical and visual evoked potential (VEP) experiments show that the masking effect critically depends on a combination of several factors: (1) the processing time of the target, (2) the order of presentation of the target and the mask, and (3) the spatial arrangement of the target and the mask. Thus, the masking effect depends on the spatial-temporal combination of these factors. Suppression was observed when the mask was positioned within a spatial range that was found to evoke inhibition, and when the temporal separation between the target and the mask was short. In contrast, lateral facilitation was observed when the mask was presented at a spatial separation that did not evoke inhibition from the target's vicinity and with a temporal sequence that preceded the target, or when it was presented simultaneously with it, but not when the target preceded the mask. We propose that masking effects, either suppression or facilitation, reflect integration into the spatial and the temporal domains of the feedforward response to the target and the lateral inputs evoked by the mask (excitatory and/or inhibitory). Because the excitation evoked by the mask develops and propagates slowly from the mask's location to the target's location, it lags behind the response to the target. On the other hand, inhibition that is produced in the vicinity of the target evolves more rapidly and follows the onset and offset of the stimulus more closely. Thus, lateral excitation that overcomes the inhibition may facilitate the grouping of local elements into a global percept by increasing the survivability of the object and its accessibility for perceptual awareness.

Perceptual facilitation, a decrease in detection threshold for low-contrast Gabor patches (GPs) occurs when the GP is flanked by collinearly oriented high-contrast patches. There is earlier evidence suggesting a spatial architecture of excitatory and inhibitory interactions. Here we used Visual Evoked Potentials (VEPs) to study the temporal structure of this process. We measured VEPs elicited by a foveal near-threshold target GP presented in isolation (T), T in the presence of two flanking collinear high-contrast GPs (lateral masking, LM), or the flankers alone (F). Stimuli were presented for 50 ms every 1000 ms. The choice of the set parameters elicited behavioral facilitation of T detection. Significant modulation of peak amplitudes in LM compared with linearly summed waveforms elicited by T and F was found for five alternating polarity components, ranging from 65 to 290 ms after stimulus onset. In the frequency domain, suppression at lower frequencies (up to 0.8 log units) was followed by facilitation at higher frequencies (4-6 Hz, up to 0.8 log units). Although no differences in the latencies were found, lateral interactions were reflected by non-linear waveform modulation of multiple components and frequencies, including components as early as 65-75 ms. Spectrum analysis suggests that both suppression and facilitation may be found for the same configuration of stimuli, simultaneously, distributed at different temporal frequencies and/or sources. The physiological correlates of lateral interactions may thus originate at multiple sources, only some of which are explicitly facilitatory. The final perceptual outcome of this complex spatio-temporal representation is determined by combining sensory and cognitive factors.

The aim of the presented research was to develop special spectacles capable of solving common ophthalmic problems as myopia, presbyopia and regular/irregular astigmatism. The method included adapting special all-optical extended depth of focus concept, taken from the field of digital imaging, to ophthalmology, and by that providing the required vision solutions. Special thin mask containing annular like replicated structure (thickness of the structure is less than one micron) was designed and proven to provide extended depth of focus. In this paper we present several experimental results as well as trials with volunteers. The testing included measuring the visual acuity under different illumination conditions (pupil size varied from 2 up to 4mm), as well as stereoscopy, color integrity, field of view and contrast. The results demonstrate improvements of up to 3 Diopters (for presbyopic that require the bifocal or the progressive lens solutions) for pupil sizes of 2-4mm. The approach has demonstrated improvement of more than 2 Diopters for regular as well as irregular astigmatism. The main advantage of the developed optical element is that it is very thin (less than few microns) and has low price, it has high energetic throughput and low chromatic aberrations and it operates over the full field of view while providing continuously focused image (in contrast to bifocal lenses having only 2 focused regions). The element also provides a solution for regular as well as irregular astigmatism that currently has no available treatment.

Background: Matrix metalloproteinases are proteolytic enzymes that degrade extracellular matrix components. Numerous studies have demonstrated that individual MMPs play a crucial role in tumor invasion and metastasis., Objective: To examine the expression of MMPs and their inhibitor TIMP-2 in neoplastic and normal thyroid tissues., Methods: We examined 33 cases of thyroid tumor (papillary, follicular and medullary carcinoma, follicular adenoma and multinodular goiter). MMP protein content and activity were measured by enzyme-linked immunosorbent assay and gel zymography. Immunohistochemistry was also performed., Results: The thyroid tissues examined secreted MMP-2 and 9 as well as TIMP-2, but only MMP-2 was significantly higher in papillary carcinoma cases compared to the adjacent normal tissue or to the other tumor entities. Increased MMP-2 immunohistochemical staining was demonstrated in the neoplastic papillary epithelial component. No significant difference was seen between papillary carcinomas with lymph node metastases and those without., Conclusions: Increased MMP-2 expression may be useful as a diagnostic marker to differentiate papillary carcinoma from other thyroid neoplasms, but it cannot serve as a useful prognostic marker.