Short-Term Saccadic Adaptation in Patients With Anisometropic Amblyopia

PURPOSE. Amblyopia is a developmental disorder characterized by impairment of spatiotemporal visual processing that also affects oculomotor and manual motor function. We investigated the effects of amblyopia on short-term visuomotor adaptation using a saccadic adaptation paradigm. METHODS. A total of 8 patients with anisometropic amblyopia and 11 visually-normal controls participated. Saccadic adaptation was induced using a double-step paradigm that displaced a saccadic visual target (at 6198) back toward central fixation by 4.28 during the ongoing saccade. Three test blocks, preadaptation, adaptation, and postadaptation, were performed sequentially while participants viewed binocularly and monocularly with the amblyopic and fellow eyes (nondominant and dominant eyes in controls) in three separate sessions. The spatial and temporal characteristics of saccadic adaptation were measured. RESULTS. Patients exhibited diminished saccadic gain adaptation. The percentage change in saccadic gain was lower in patients during amblyopic eye and binocular viewing compared to controls. Saccadic latencies were longer, and saccadic gains and latencies were more variable in patients during amblyopic eye viewing. The time constants of adaptation were comparable between controls and patients under all viewing conditions. CONCLUSIONS. The short-term adaptation of saccadic gain was weaker and more variable in patients during amblyopic eye and binocular viewing. Our findings suggest that visual error information necessary for adaptation is imprecise in amblyopia, leading to reduced modulation of saccadic gain, and support the proposal that the error signal driving saccadic adaptation is visual

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

Background: Impairment 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. Methods: Thirteen 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 (R 2) which correlates the spatial position of the limb during the movement to endpoint position. Results: Patients 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 R 2 values at 70 % of movement time along the elevation and depth axes during amblyopic eye viewing. Conclusion: Sensory uncertainty due to amblyopia leads to reduced precision of the motor plan. The ability to implemen

Static Ocular Counterroll in Patients with Skew Deviation

Static ocular counterroll (OCR) generates compensatory torsional eye movements during static head tilt and it is mediated by the utricles in the inner ear

Static Ocular Counterroll in Patients with Skew Deviation

Static ocular counterroll (OCR) generates compensatory torsional eye movements during static head tilt and it is mediated by the utricles in the inner ear

A new method for testing letter contrast sensitivity in a clinical setting: Comparing M&S smart system II letter contrast test with Pelli-Robson chart

The M&S smart system II (MSSSII; M&S Technologies Inc, Illinois) is a novel computer-based contrast sensitivity assessment tool. The purpose of this study was to compare the utility of the MSSSII to the Pelli-Robson chart as a clinical test for contrast sensitivity

Effects of Earth-Fixed vs Head-Fixed Target on Ocular Counterroll

Ocular counter-roll (OCR) generates compensatory torsional eye movements during static head tilt. OCR is important from a clinical standpoint, because it explains the abnormal compensatory head tilt in patients with trochlear nerve palsy, and it forms the basis of the Bielschowsky head-tilt test

Test-Retest Reliability of Hemifield, Central-Field and Full-Field Chromatic Pupillometry for Assessing the Function of Melanopsin-Containing Retinal Ganglion Cells

"A sustained pupil constriction can be observed after the offset of a bright blue light stimulus. This post-illumination pupil response (PIPR) is produced by the intrinsically photosensitive melanopsin-containing retinal ganglion cells (ipRGCs), and can be measured by chromatic pupillometry. We previously described a clinically friendly chromatic pupillometry protocol that can induce PIPR with a brief blue light stimulus. The present study is to evaluate the test-retest reliability of current methods of inducing PIPR under hemifield, central-field and full-field stimulation conditions.

F.Wong, “Effects of anisometropic amblyopia on visuomotor behavior, III: temporal eye-hand coordination during reaching

PURPOSE. Impairment of spatiotemporal visual processing is the hallmark of amblyopia, but its effects on eye movements during visuomotor tasks have rarely been studied. Here the authors investigate how visual deficits in anisometropic amblyopia affect saccadic eye movements. METHODS. Thirteen patients with anisometropic amblyopia and 13 control subjects participated. Participants executed saccades and manual reaching movements to a target presented randomly 5°or 10°to the left or right of fixation in three viewing conditions: binocular, amblyopic, and fellow eye viewing. Latency, amplitude, and peak velocity of primary and corrective saccades were measured. RESULTS. Initiation of primary saccades was delayed and more variable when patients viewed monocularly with their amblyopic eye. During binocular viewing, saccadic latency exhibited increased variability and no binocular advantage in patients (i.e., mean latency was similar to that during fellow eye viewing). Mean amplitude and peak velocity of primary saccades were comparable between patients and control subjects; however, patients exhibited greater variability in saccade amplitude. The frequency of corrective saccades was greater when patients viewed with their fellow eye than it was with binocular or amblyopic eye viewing. Latency, amplitude, and peak velocity of corrective saccades in patients were normal in all viewing conditions. CONCLUSIONS. Saccades had longer latency and decreased precision in amblyopia. Once saccades were initiated, however, the dynamics of saccades were not altered. These findings suggest that amblyopia is associated with slower visual processing in the afferent (sensory) pathway rather than a deficit in the efferent (motor) pathway of the saccadic system. (Invest Ophthalmol Vis Sci. 2010;51:6348 -6354

Endpoint precision of the reach (mean ± standard deviation).

<p>BE: binocular; LE: left eye; RE: right eye; FE: fellow eye; AE: amblyopic eye.</p