Effects of Anisometropic Amblyopia on Visuomotor Behavior, Part 2: Visually Guided Reaching

Niechwiej-Szwedo, Ewa; Goltz, Herbert C.; Chandrakumar, Manokaraananthan; Hirji, Z.; Crawford, J. Douglas; Wong, Agnes M. F.

doi:10.1167/iovs.10-6092

Cited by 68 publications

(76 citation statements)

References 64 publications

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“…Importantly, this extension of the deceleration phase was associated with reduced antisaccade end-point error. Our findings are analogous to what has been reported previously for upper limb reaching movements [38], [39], [40], [41]. Specifically, it has been proposed that online modifications of the limb trajectory are made in the deceleration phase of the reaching movement.…”

Section: Discussionsupporting

confidence: 91%

Error Correcting Mechanisms during Antisaccades: Contribution of Online Control during Primary Saccades and Offline Control via Secondary Saccades

et al. 2013

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Errors in eye movements can be corrected during the ongoing saccade through in-flight modifications (i.e., online control), or by programming a secondary eye movement (i.e., offline control). In a reflexive saccade task, the oculomotor system can use extraretinal information (i.e., efference copy) online to correct errors in the primary saccade, and offline retinal information to generate a secondary corrective saccade. The purpose of this study was to examine the error correction mechanisms in the antisaccade task. The roles of extraretinal and retinal feedback in maintaining eye movement accuracy were investigated by presenting visual feedback at the spatial goal of the antisaccade. We found that online control for antisaccade is not affected by the presence of visual feedback; that is whether visual feedback is present or not, the duration of the deceleration interval was extended and significantly correlated with reduced antisaccade endpoint error. We postulate that the extended duration of deceleration is a feature of online control during volitional saccades to improve their endpoint accuracy. We found that secondary saccades were generated more frequently in the antisaccade task compared to the reflexive saccade task. Furthermore, we found evidence for a greater contribution from extraretinal sources of feedback in programming the secondary “corrective” saccades in the antisaccade task. Nonetheless, secondary saccades were more corrective for the remaining antisaccade amplitude error in the presence of visual feedback of the target. Taken together, our results reveal a distinctive online error control strategy through an extension of the deceleration interval in the antisaccade task. Target feedback does not improve online control, rather it improves the accuracy of secondary saccades in the antisaccade task.

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Section: Discussionsupporting

confidence: 91%

Error Correcting Mechanisms during Antisaccades: Contribution of Online Control during Primary Saccades and Offline Control via Secondary Saccades

et al. 2013

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“…Also, consistent with the results in our previous study with a smaller sample size [57], we found no differences between patients with mild and severe amblyopia for other kinematic parameters which reflect the planning stage of the movement, including peak acceleration, peak velocity, and the duration of the acceleration phase. In fact, both groups of patients showed similar changes in the early kinematic parameters in comparison to age-matched control participants.…”

Section: Discussionsupporting

confidence: 92%

The Effect of Sensory Uncertainty Due to Amblyopia (Lazy Eye) on the Planning and Execution of Visually-Guided 3D Reaching Movements

et al. 2012

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BackgroundImpairment of spatiotemporal visual processing in amblyopia has been studied extensively, but its effects on visuomotor tasks have rarely been examined. Here, we investigate how visual deficits in amblyopia affect motor planning and online control of visually-guided, unconstrained reaching movements.MethodsThirteen patients with mild amblyopia, 13 with severe amblyopia and 13 visually-normal participants were recruited. Participants reached and touched a visual target during binocular and monocular viewing. Motor planning was assessed by examining spatial variability of the trajectory at 50–100 ms after movement onset. Online control was assessed by examining the endpoint variability and by calculating the coefficient of determination (R2) which correlates the spatial position of the limb during the movement to endpoint position.ResultsPatients with amblyopia had reduced precision of the motor plan in all viewing conditions as evidenced by increased variability of the reach early in the trajectory. Endpoint precision was comparable between patients with mild amblyopia and control participants. Patients with severe amblyopia had reduced endpoint precision along azimuth and elevation during amblyopic eye viewing only, and along the depth axis in all viewing conditions. In addition, they had significantly higher R2 values at 70% of movement time along the elevation and depth axes during amblyopic eye viewing.ConclusionSensory uncertainty due to amblyopia leads to reduced precision of the motor plan. The ability to implement online corrections depends on the severity of the visual deficit, viewing condition, and the axis of the reaching movement. Patients with mild amblyopia used online control effectively to compensate for the reduced precision of the motor plan. In contrast, patients with severe amblyopia were not able to use online control as effectively to amend the limb trajectory especially along the depth axis, which could be due to their abnormal stereopsis.

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“…Decorrelated binocular vision can have a wide-ranging impact upon aspects of visual function, including depth judgments, [33][34][35][36] visually guided reaching/grasping kinematics, 34,[37][38][39][40] obstacle negotiation, 41 and fine visuomotor tasks. 35,36,[42][43][44][45][46] Prior to this only a small number of studies have attempted to use binocular methods of measuring perceptual visual distortions.…”

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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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Effects of Anisometropic Amblyopia on Visuomotor Behavior, Part 2: Visually Guided Reaching

Cited by 68 publications

References 64 publications

Error Correcting Mechanisms during Antisaccades: Contribution of Online Control during Primary Saccades and Offline Control via Secondary Saccades

Error Correcting Mechanisms during Antisaccades: Contribution of Online Control during Primary Saccades and Offline Control via Secondary Saccades

The Effect of Sensory Uncertainty Due to Amblyopia (Lazy Eye) on the Planning and Execution of Visually-Guided 3D Reaching Movements

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

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