Perceptual Learning Improves Stereoacuity in Amblyopia

Xiao, Jie; Jia, Wuli; Feng, Lei; Lü, Zhong-Lin; Huang, Chang-Bing

doi:10.1167/iovs.13-12627

Cited by 70 publications

(63 citation statements)

References 58 publications

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“…Their recovered stereopsis is based on perceiving depth by detecting binocular disparity, but has reduced resolution and precision. Similar improvements were recently reported in a group of anisometropic and ametropic amblyopes who were trained with anaglyphic textures with different disparities (Xi et al, 2014). …”

Section: Can Stereopsis Be Recovered In Children and Adults With Asupporting

confidence: 85%

Stereopsis and amblyopia: A mini-review

2015

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Amblyopia is a neuro-developmental disorder of the visual cortex that arises from abnormal visual experience early in life. Amblyopia is clinically important because it is a major cause of vision loss in infants and young children. Amblyopia is also of basic interest because it reflects the neural impairment that occurs when normal visual development is disrupted. Amblyopia provides an ideal model for understanding when and how brain plasticity may be harnessed for recovery of function. Over the past two decades there has been a rekindling of interest in developing more effective methods for treating amblyopia, and for extending the treatment beyond the critical period, as exemplified by new clinical trials and new basic research studies. The focus of this review is on stereopsis and its potential for recovery. Impaired stereoscopic depth perception is the most common deficit associated with amblyopia under ordinary (binocular) viewing conditions (Webber & Wood, 2005). Our review of the extant literature suggests that this impairment may have a substantial impact on visuomotor tasks, difficulties in playing sports in children and locomoting safely in older adults. Furthermore, impaired stereopsis may also limit career options for amblyopes. Finally, stereopsis is more impacted in strabismic than in anisometropic amblyopia. Our review of the various approaches to treating amblyopia (patching, perceptual learning, videogames) suggests that there are several promising new approaches to recovering stereopsis in both anisometropic and strabismic amblyopes. However, recovery of stereoacuity may require more active treatment in strabismic than in anisometropic amblyopia. Individuals with strabismic amblyopia have a very low probability of improvement with monocular training; however they fare better with dichoptic training than with monocular training, and even better with direct stereo training.

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Section: Can Stereopsis Be Recovered In Children and Adults With Asupporting

confidence: 85%

Stereopsis and amblyopia: A mini-review

2015

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“…This is in keeping with the findings of previous studies. 15,19 Study findings regarding the relationship of binocularity to perceptual visual distortions could provide further justification for the focus on treatment methodologies avoiding binocular decorrelation of the eyes during amblyopia treatment, such as recent binocular perceptual learning paradigms 51,52 and the use of atropine penalization, determined as effective as occlusion for amblyopia treatment. 1 However, it is also important to consider the possibility that individuals manifesting these perceptual visual distortions under such dichoptic testing conditions, where the amblyopic eye contributes to portions of the visual percept, may actually struggle with perceptual learning techniques that utilize similarly presented stimuli to encourage binocular cooperation.…”

Section: Discussion Exploration Of Global Distortion and Uncertainty mentioning

confidence: 99%

Perceptual Visual Distortions in Adult Amblyopia and Their Relationship to Clinical Features

Piano

Bex

Simmers

2015

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Develop a paradigm to map binocular perceptual visual distortions in adult amblyopes and visually normal controls, measure their stability over time, and determine the relationship between strength of binocular single vision and distortion magnitude.METHODS. Perceptual visual distortions were measured in 24 strabismic, anisometropic, or microtropic amblyopes (interocular acuity difference ‡ 0.200 logMAR or history of amblyopia treatment) and 10 controls (mean age 27.13 6 10.20 years). The task was mouse-based target alignment on a stereoscopic liquid crystal display monitor, measured binocularly five times during viewing dichoptically through active shutter glasses, amblyopic eye viewing crosshairs, fellow eye viewing single target dots (16 locations within central 58), and five times nondichoptically, with all stimuli visible to either eye. Measurements were repeated over time (1 week, 1 month) in eight amblyopic subjects, evaluating test-retest reliability. Measurements were also correlated against logMAR visual acuity, horizontal prism motor fusion range, Frisby/Preschool Randot stereoacuity, and heterophoria/heterotropia prism cover test measurement.RESULTS. Sixty-seven percent (16/24) of amblyopes had significant perceptual visual distortions under dichoptic viewing conditions compared to nondichoptic viewing conditions and dichoptic control group performance. Distortions correlated with the strength of motor fusion (r ¼ À0.417, P ¼ 0.043) and log stereoacuity (r ¼ 0.492, P ¼ 0.015), as well as near angle of heterotropic/heterophoric deviation (r ¼ 0.740, P < 0.001), and, marginally, amblyopia depth (r ¼ 0.405, P ¼ 0.049). Global distortion index (GDI, mean displacement) remained, overall, consistent over time (median change in GDI between baseline and 1 week ¼ À0.038, 1 month ¼ À0.088; x-axis Z ¼ 4.4256, P < 0.001; y-axis Z ¼ 5.0547, P < 0.001).CONCLUSIONS. Perceptual visual distortions are stable over time and associated with poorer binocular function, greater amblyopia depth, and larger angles of ocular deviation. Assessment of distortions may be relevant for recent perceptual learning paradigms specifically targeting binocular vision.

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“…Many dichoptic training studies use signal integration training paradigms, in which the task elements are separated between the two eyes and must be integrated for successful task completion. [8][9][10][11][12][13][14][15] Dichoptic training may assist information integration from the two eyes to help recover stereovision in amblyopic patients. 6 In a previous study, we adopted a different dichoptic demasking training paradigm (details provided in Methods and Results sections), in which the observers were trained to discriminate the contrast or orientation of a Gabor stimulus presented to the AE while discounting the masking effect from a noise masker presented to the FE.…”

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confidence: 99%

Dichoptic De-Masking Learning in Adults With Amblyopia and Its Mechanisms

Liu

Zhang

2019

Invest. Ophthalmol. Vis. Sci.

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Citation: Liu X-Y, Zhang J-Y. Dichoptic de-masking learning in adults with amblyopia and its mechanisms. Invest Ophthalmol Vis Sci. 2019;60:2968-2977. https://doi.org/10.1167 PURPOSE. Recently, we reported that dichoptic de-masking training can further boost stereoacuity, but not visual acuity, in adults with amblyopia after extensive monocular perceptual training. Here, we investigated whether this dichoptic training targets on interocular suppression directly, or improves vision through high-level brain mechanisms.METHODS. Eleven adults with amblyopia first used amblyopic eyes (AEs) to perform contrast (n ¼ 6) or orientation (n ¼ 5) discrimination training, while resisting dichoptic noise masking from fellow eyes (FEs). Learning was indicated by increased maximal tolerable noise contrast (TNC) for AE contrast/orientation discrimination. After dichoptic training, six observers continued to use AEs to perform monocular training for nine sessions. RESULTS.(1) Training of dichoptic de-masking doubled maximal TNC, but learning did not transfer much to the same task at an orthogonal orientation or a different task, showing orientation/task specificities. (2) Following a training-plus-exposure (TPE) protocol, AEs then received exposure of the orthogonal orientation by performing the other orientation/contrast discrimination task at the orthogonal orientation. After this TPE training, dichoptic learning with the original discrimination task transferred to the orthogonal orientation. (3) Dichoptic training improved AE's acuity (1.2 lines), stereoacuity (60.2%), and contrast sensitivity (mainly at higher spatial frequencies). (4) Additional monocular training did not produce further acuity and stereoacuity gains.CONCLUSIONS. The initial orientation/task specificities exclude the possibility that dichoptic training reduces physiological interocular suppression. The later transfer of learning to an orthogonal orientation with TPE training suggests improvement in high-level brain processing. Dichoptic training may strengthen top-down attention to AEs to counter the impacts of attentional bias to FEs and/or physiological interocular suppression and improve stereoacuity.

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Perceptual Learning Improves Stereoacuity in Amblyopia

Abstract: Perceptual learning is effective in improving stereo vision in observers with amblyopia. These results, together with previous evidence, suggest that structured monocular and binocular training might be necessary to fully recover degraded visual functions in amblyopia. Chinese Abstract.

Cited by 70 publications

References 58 publications

Stereopsis and amblyopia: A mini-review

Stereopsis and amblyopia: A mini-review

Perceptual Visual Distortions in Adult Amblyopia and Their Relationship to Clinical Features

Dichoptic De-Masking Learning in Adults With Amblyopia and Its Mechanisms

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